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third-party-mirror/openjdk/jdk25u/refs/heads/master/./src/hotspot/os/linux/os_linux.cpp
blob: 49125ae8954b5c98cb034965d6831044c3b1c8fc [file] [edit]
/*
* Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2015, 2024 SAP SE. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "classfile/vmSymbols.hpp"
#include "code/vtableStubs.hpp"
#include "compiler/compileBroker.hpp"
#include "compiler/disassembler.hpp"
#include "hugepages.hpp"
#include "interpreter/interpreter.hpp"
#include "jvm.h"
#include "jvmtifiles/jvmti.h"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/allocation.inline.hpp"
#include "nmt/memTracker.hpp"
#include "oops/oop.inline.hpp"
#include "osContainer_linux.hpp"
#include "os_linux.inline.hpp"
#include "os_posix.inline.hpp"
#include "prims/jniFastGetField.hpp"
#include "prims/jvm_misc.hpp"
#include "runtime/arguments.hpp"
#include "runtime/atomic.hpp"
#include "runtime/globals.hpp"
#include "runtime/globals_extension.hpp"
#include "runtime/init.hpp"
#include "runtime/interfaceSupport.inline.hpp"
#include "runtime/java.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/objectMonitor.hpp"
#include "runtime/osInfo.hpp"
#include "runtime/osThread.hpp"
#include "runtime/perfMemory.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/stubRoutines.hpp"
#include "runtime/threads.hpp"
#include "runtime/threadSMR.hpp"
#include "runtime/timer.hpp"
#include "runtime/vm_version.hpp"
#include "semaphore_posix.hpp"
#include "services/runtimeService.hpp"
#include "signals_posix.hpp"
#include "utilities/align.hpp"
#include "utilities/checkedCast.hpp"
#include "utilities/debug.hpp"
#include "utilities/decoder.hpp"
#include "utilities/defaultStream.hpp"
#include "utilities/elfFile.hpp"
#include "utilities/events.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/macros.hpp"
#include "utilities/powerOfTwo.hpp"
#include "utilities/vmError.hpp"
#if INCLUDE_JFR
#include "jfr/jfrEvents.hpp"
#include "jfr/support/jfrNativeLibraryLoadEvent.hpp"
#endif
// put OS-includes here
# include <ctype.h>
# include <stdlib.h>
# include <sys/types.h>
# include <sys/mman.h>
# include <sys/stat.h>
# include <sys/select.h>
# include <sys/sendfile.h>
# include <pthread.h>
# include <signal.h>
# include <endian.h>
# include <errno.h>
# include <fenv.h>
# include <dlfcn.h>
# include <stdio.h>
# include <unistd.h>
# include <sys/resource.h>
# include <pthread.h>
# include <sys/stat.h>
# include <sys/time.h>
# include <sys/times.h>
# include <sys/utsname.h>
# include <sys/socket.h>
# include <pwd.h>
# include <poll.h>
# include <fcntl.h>
# include <string.h>
# include <syscall.h>
# include <sys/sysinfo.h>
# include <sys/ipc.h>
# include <link.h>
# include <stdint.h>
# include <inttypes.h>
# include <sys/ioctl.h>
# include <linux/elf-em.h>
# include <sys/prctl.h>
#ifdef __GLIBC__
# include <malloc.h>
#endif
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#include <sched.h>
#undef _GNU_SOURCE
#else
#include <sched.h>
#endif
// if RUSAGE_THREAD for getrusage() has not been defined, do it here. The code calling
// getrusage() is prepared to handle the associated failure.
#ifndef RUSAGE_THREAD
#define RUSAGE_THREAD (1) /* only the calling thread */
#endif
#define MAX_PATH (2 * K)
#ifdef MUSL_LIBC
// dlvsym is not a part of POSIX
// and musl libc doesn't implement it.
static void *dlvsym(void *handle,
const char *symbol,
const char *version) {
// load the latest version of symbol
return dlsym(handle, symbol);
}
#endif
enum CoredumpFilterBit {
FILE_BACKED_PVT_BIT = 1 << 2,
FILE_BACKED_SHARED_BIT = 1 << 3,
LARGEPAGES_BIT = 1 << 6,
DAX_SHARED_BIT = 1 << 8
};
////////////////////////////////////////////////////////////////////////////////
// global variables
julong os::Linux::_physical_memory = 0;
address os::Linux::_initial_thread_stack_bottom = nullptr;
uintptr_t os::Linux::_initial_thread_stack_size = 0;
int (*os::Linux::_pthread_getcpuclockid)(pthread_t, clockid_t *) = nullptr;
int (*os::Linux::_pthread_setname_np)(pthread_t, const char*) = nullptr;
pthread_t os::Linux::_main_thread;
bool os::Linux::_supports_fast_thread_cpu_time = false;
const char * os::Linux::_libc_version = nullptr;
const char * os::Linux::_libpthread_version = nullptr;
bool os::Linux::_thp_requested{false};
#ifdef __GLIBC__
// We want to be buildable and runnable on older and newer glibcs, so resolve both
// mallinfo and mallinfo2 dynamically.
struct old_mallinfo {
int arena;
int ordblks;
int smblks;
int hblks;
int hblkhd;
int usmblks;
int fsmblks;
int uordblks;
int fordblks;
int keepcost;
};
typedef struct old_mallinfo (*mallinfo_func_t)(void);
static mallinfo_func_t g_mallinfo = nullptr;
struct new_mallinfo {
size_t arena;
size_t ordblks;
size_t smblks;
size_t hblks;
size_t hblkhd;
size_t usmblks;
size_t fsmblks;
size_t uordblks;
size_t fordblks;
size_t keepcost;
};
typedef struct new_mallinfo (*mallinfo2_func_t)(void);
static mallinfo2_func_t g_mallinfo2 = nullptr;
typedef int (*malloc_info_func_t)(int options, FILE *stream);
static malloc_info_func_t g_malloc_info = nullptr;
#endif // __GLIBC__
// If the VM might have been created on the primordial thread, we need to resolve the
// primordial thread stack bounds and check if the current thread might be the
// primordial thread in places. If we know that the primordial thread is never used,
// such as when the VM was created by one of the standard java launchers, we can
// avoid this
static bool suppress_primordial_thread_resolution = false;
// utility functions
julong os::Linux::available_memory_in_container() {
julong avail_mem = static_cast<julong>(-1L);
if (OSContainer::is_containerized()) {
jlong mem_limit = OSContainer::memory_limit_in_bytes();
jlong mem_usage;
if (mem_limit > 0 && (mem_usage = OSContainer::memory_usage_in_bytes()) < 1) {
log_debug(os, container)("container memory usage failed: " JLONG_FORMAT ", using host value", mem_usage);
}
if (mem_limit > 0 && mem_usage > 0) {
avail_mem = mem_limit > mem_usage ? (julong)mem_limit - (julong)mem_usage : 0;
}
}
return avail_mem;
}
julong os::available_memory() {
return Linux::available_memory();
}
julong os::Linux::available_memory() {
julong avail_mem = available_memory_in_container();
if (avail_mem != static_cast<julong>(-1L)) {
log_trace(os)("available container memory: " JULONG_FORMAT, avail_mem);
return avail_mem;
}
FILE *fp = os::fopen("/proc/meminfo", "r");
if (fp != nullptr) {
char buf[80];
do {
if (fscanf(fp, "MemAvailable: " JULONG_FORMAT " kB", &avail_mem) == 1) {
avail_mem *= K;
break;
}
} while (fgets(buf, sizeof(buf), fp) != nullptr);
fclose(fp);
}
if (avail_mem == static_cast<julong>(-1L)) {
avail_mem = free_memory();
}
log_trace(os)("available memory: " JULONG_FORMAT, avail_mem);
return avail_mem;
}
julong os::free_memory() {
return Linux::free_memory();
}
julong os::Linux::free_memory() {
// values in struct sysinfo are "unsigned long"
struct sysinfo si;
julong free_mem = available_memory_in_container();
if (free_mem != static_cast<julong>(-1L)) {
log_trace(os)("free container memory: " JULONG_FORMAT, free_mem);
return free_mem;
}
sysinfo(&si);
free_mem = (julong)si.freeram * si.mem_unit;
log_trace(os)("free memory: " JULONG_FORMAT, free_mem);
return free_mem;
}
jlong os::total_swap_space() {
if (OSContainer::is_containerized()) {
if (OSContainer::memory_limit_in_bytes() > 0) {
return (jlong)(OSContainer::memory_and_swap_limit_in_bytes() - OSContainer::memory_limit_in_bytes());
}
}
struct sysinfo si;
int ret = sysinfo(&si);
if (ret != 0) {
return -1;
}
return (jlong)(si.totalswap * si.mem_unit);
}
static jlong host_free_swap() {
struct sysinfo si;
int ret = sysinfo(&si);
if (ret != 0) {
return -1;
}
return (jlong)(si.freeswap * si.mem_unit);
}
jlong os::free_swap_space() {
// os::total_swap_space() might return the containerized limit which might be
// less than host_free_swap(). The upper bound of free swap needs to be the lower of the two.
jlong host_free_swap_val = MIN2(os::total_swap_space(), host_free_swap());
assert(host_free_swap_val >= 0, "sysinfo failed?");
if (OSContainer::is_containerized()) {
jlong mem_swap_limit = OSContainer::memory_and_swap_limit_in_bytes();
jlong mem_limit = OSContainer::memory_limit_in_bytes();
if (mem_swap_limit >= 0 && mem_limit >= 0) {
jlong delta_limit = mem_swap_limit - mem_limit;
if (delta_limit <= 0) {
return 0;
}
jlong mem_swap_usage = OSContainer::memory_and_swap_usage_in_bytes();
jlong mem_usage = OSContainer::memory_usage_in_bytes();
if (mem_swap_usage > 0 && mem_usage > 0) {
jlong delta_usage = mem_swap_usage - mem_usage;
if (delta_usage >= 0) {
jlong free_swap = delta_limit - delta_usage;
return free_swap >= 0 ? free_swap : 0;
}
}
}
// unlimited or not supported. Fall through to return host value
log_trace(os,container)("os::free_swap_space: container_swap_limit=" JLONG_FORMAT
" container_mem_limit=" JLONG_FORMAT " returning host value: " JLONG_FORMAT,
mem_swap_limit, mem_limit, host_free_swap_val);
}
return host_free_swap_val;
}
julong os::physical_memory() {
jlong phys_mem = 0;
if (OSContainer::is_containerized()) {
jlong mem_limit;
if ((mem_limit = OSContainer::memory_limit_in_bytes()) > 0) {
log_trace(os)("total container memory: " JLONG_FORMAT, mem_limit);
return mem_limit;
}
}
phys_mem = Linux::physical_memory();
log_trace(os)("total system memory: " JLONG_FORMAT, phys_mem);
return phys_mem;
}
// Returns the resident set size (RSS) of the process.
// Falls back to using VmRSS from /proc/self/status if /proc/self/smaps_rollup is unavailable.
// Note: On kernels with memory cgroups or shared memory, VmRSS may underreport RSS.
// Users requiring accurate RSS values should be aware of this limitation.
size_t os::rss() {
size_t size = 0;
os::Linux::accurate_meminfo_t accurate_info;
if (os::Linux::query_accurate_process_memory_info(&accurate_info) && accurate_info.rss != -1) {
size = accurate_info.rss * K;
} else {
os::Linux::meminfo_t info;
if (os::Linux::query_process_memory_info(&info)) {
size = info.vmrss * K;
}
}
return size;
}
static uint64_t initial_total_ticks = 0;
static uint64_t initial_steal_ticks = 0;
static bool has_initial_tick_info = false;
static void next_line(FILE *f) {
int c;
do {
c = fgetc(f);
} while (c != '\n' && c != EOF);
}
void os::Linux::kernel_version(long* major, long* minor, long* patch) {
*major = 0;
*minor = 0;
*patch = 0;
struct utsname buffer;
int ret = uname(&buffer);
if (ret != 0) {
log_warning(os)("uname(2) failed to get kernel version: %s", os::errno_name(ret));
return;
}
int nr_matched = sscanf(buffer.release, "%ld.%ld.%ld", major, minor, patch);
if (nr_matched != 3) {
log_warning(os)("Parsing kernel version failed, expected 3 version numbers, only matched %d", nr_matched);
}
}
int os::Linux::kernel_version_compare(long major1, long minor1, long patch1,
long major2, long minor2, long patch2) {
// Compare major versions
if (major1 > major2) return 1;
if (major1 < major2) return -1;
// Compare minor versions
if (minor1 > minor2) return 1;
if (minor1 < minor2) return -1;
// Compare patchlevel versions
if (patch1 > patch2) return 1;
if (patch1 < patch2) return -1;
return 0;
}
bool os::Linux::get_tick_information(CPUPerfTicks* pticks, int which_logical_cpu) {
FILE* fh;
uint64_t userTicks, niceTicks, systemTicks, idleTicks;
// since at least kernel 2.6 : iowait: time waiting for I/O to complete
// irq: time servicing interrupts; softirq: time servicing softirqs
uint64_t iowTicks = 0, irqTicks = 0, sirqTicks= 0;
// steal (since kernel 2.6.11): time spent in other OS when running in a virtualized environment
uint64_t stealTicks = 0;
// guest (since kernel 2.6.24): time spent running a virtual CPU for guest OS under the
// control of the Linux kernel
uint64_t guestNiceTicks = 0;
int logical_cpu = -1;
const int required_tickinfo_count = (which_logical_cpu == -1) ? 4 : 5;
int n;
memset(pticks, 0, sizeof(CPUPerfTicks));
if ((fh = os::fopen("/proc/stat", "r")) == nullptr) {
return false;
}
if (which_logical_cpu == -1) {
n = fscanf(fh, "cpu " UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " "
UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " "
UINT64_FORMAT " " UINT64_FORMAT " ",
&userTicks, &niceTicks, &systemTicks, &idleTicks,
&iowTicks, &irqTicks, &sirqTicks,
&stealTicks, &guestNiceTicks);
} else {
// Move to next line
next_line(fh);
// find the line for requested cpu faster to just iterate linefeeds?
for (int i = 0; i < which_logical_cpu; i++) {
next_line(fh);
}
n = fscanf(fh, "cpu%u " UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " "
UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " " UINT64_FORMAT " "
UINT64_FORMAT " " UINT64_FORMAT " ",
&logical_cpu, &userTicks, &niceTicks,
&systemTicks, &idleTicks, &iowTicks, &irqTicks, &sirqTicks,
&stealTicks, &guestNiceTicks);
}
fclose(fh);
if (n < required_tickinfo_count || logical_cpu != which_logical_cpu) {
return false;
}
pticks->used = userTicks + niceTicks;
pticks->usedKernel = systemTicks + irqTicks + sirqTicks;
pticks->total = userTicks + niceTicks + systemTicks + idleTicks +
iowTicks + irqTicks + sirqTicks + stealTicks + guestNiceTicks;
if (n > required_tickinfo_count + 3) {
pticks->steal = stealTicks;
pticks->has_steal_ticks = true;
} else {
pticks->steal = 0;
pticks->has_steal_ticks = false;
}
return true;
}
#ifndef SYS_gettid
// i386: 224, amd64: 186, sparc: 143
#if defined(__i386__)
#define SYS_gettid 224
#elif defined(__amd64__)
#define SYS_gettid 186
#elif defined(__sparc__)
#define SYS_gettid 143
#else
#error "Define SYS_gettid for this architecture"
#endif
#endif // SYS_gettid
// pid_t gettid()
//
// Returns the kernel thread id of the currently running thread. Kernel
// thread id is used to access /proc.
pid_t os::Linux::gettid() {
long rslt = syscall(SYS_gettid);
assert(rslt != -1, "must be."); // old linuxthreads implementation?
return (pid_t)rslt;
}
// Returns the amount of swap currently configured, in bytes.
// This can change at any time.
julong os::Linux::host_swap() {
struct sysinfo si;
sysinfo(&si);
return (julong)(si.totalswap * si.mem_unit);
}
// Most versions of linux have a bug where the number of processors are
// determined by looking at the /proc file system. In a chroot environment,
// the system call returns 1.
static bool unsafe_chroot_detected = false;
static const char *unstable_chroot_error = "/proc file system not found.\n"
"Java may be unstable running multithreaded in a chroot "
"environment on Linux when /proc filesystem is not mounted.";
void os::Linux::initialize_system_info() {
set_processor_count((int)sysconf(_SC_NPROCESSORS_CONF));
if (processor_count() == 1) {
pid_t pid = os::Linux::gettid();
char fname[32];
jio_snprintf(fname, sizeof(fname), "/proc/%d", pid);
FILE *fp = os::fopen(fname, "r");
if (fp == nullptr) {
unsafe_chroot_detected = true;
} else {
fclose(fp);
}
}
_physical_memory = (julong)sysconf(_SC_PHYS_PAGES) * (julong)sysconf(_SC_PAGESIZE);
assert(processor_count() > 0, "linux error");
}
void os::init_system_properties_values() {
// The next steps are taken in the product version:
//
// Obtain the JAVA_HOME value from the location of libjvm.so.
// This library should be located at:
// <JAVA_HOME>/lib/{client|server}/libjvm.so.
//
// If "/jre/lib/" appears at the right place in the path, then we
// assume libjvm.so is installed in a JDK and we use this path.
//
// Otherwise exit with message: "Could not create the Java virtual machine."
//
// The following extra steps are taken in the debugging version:
//
// If "/jre/lib/" does NOT appear at the right place in the path
// instead of exit check for $JAVA_HOME environment variable.
//
// If it is defined and we are able to locate $JAVA_HOME/jre/lib/<arch>,
// then we append a fake suffix "hotspot/libjvm.so" to this path so
// it looks like libjvm.so is installed there
// <JAVA_HOME>/jre/lib/<arch>/hotspot/libjvm.so.
//
// Otherwise exit.
//
// Important note: if the location of libjvm.so changes this
// code needs to be changed accordingly.
// See ld(1):
// The linker uses the following search paths to locate required
// shared libraries:
// 1: ...
// ...
// 7: The default directories, normally /lib and /usr/lib.
#ifndef OVERRIDE_LIBPATH
#if defined(_LP64)
#define DEFAULT_LIBPATH "/usr/lib64:/lib64:/lib:/usr/lib"
#else
#define DEFAULT_LIBPATH "/lib:/usr/lib"
#endif
#else
#define DEFAULT_LIBPATH OVERRIDE_LIBPATH
#endif
// Base path of extensions installed on the system.
#define SYS_EXT_DIR "/usr/java/packages"
#define EXTENSIONS_DIR "/lib/ext"
#define JVM_LIB_NAME "libjvm.so"
// Buffer that fits several snprintfs.
// Note that the space for the colon and the trailing null are provided
// by the nulls included by the sizeof operator.
const size_t bufsize =
MAX2((size_t)MAXPATHLEN, // For dll_dir & friends.
(size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(SYS_EXT_DIR) + sizeof(EXTENSIONS_DIR)); // extensions dir
char *buf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
// sysclasspath, java_home, dll_dir
{
char *pslash;
os::jvm_path(buf, bufsize);
// Found the full path to the binary. It is normally of this structure:
// <jdk_path>/lib/<hotspot_variant>/libjvm.so
// but can also be like this for a statically linked binary:
// <jdk_path>/bin/<executable>
pslash = strrchr(buf, '/');
if (pslash != nullptr) {
if (strncmp(pslash + 1, JVM_LIB_NAME, strlen(JVM_LIB_NAME)) == 0) {
// Binary name is libjvm.so. Get rid of /libjvm.so.
*pslash = '\0';
}
// Get rid of /<hotspot_variant>, if binary is libjvm.so,
// or cut off /<executable>, if it is a statically linked binary.
pslash = strrchr(buf, '/');
if (pslash != nullptr) {
*pslash = '\0';
}
}
Arguments::set_dll_dir(buf);
// Get rid of /lib, if binary is libjvm.so,
// or cut off /bin, if it is a statically linked binary.
if (pslash != nullptr) {
pslash = strrchr(buf, '/');
if (pslash != nullptr) {
*pslash = '\0';
}
}
Arguments::set_java_home(buf);
if (!set_boot_path('/', ':')) {
vm_exit_during_initialization("Failed setting boot class path.", nullptr);
}
}
// Where to look for native libraries.
//
// Note: Due to a legacy implementation, most of the library path
// is set in the launcher. This was to accommodate linking restrictions
// on legacy Linux implementations (which are no longer supported).
// Eventually, all the library path setting will be done here.
//
// However, to prevent the proliferation of improperly built native
// libraries, the new path component /usr/java/packages is added here.
// Eventually, all the library path setting will be done here.
{
// Get the user setting of LD_LIBRARY_PATH, and prepended it. It
// should always exist (until the legacy problem cited above is
// addressed).
const char *v = ::getenv("LD_LIBRARY_PATH");
const char *v_colon = ":";
if (v == nullptr) { v = ""; v_colon = ""; }
// That's +1 for the colon and +1 for the trailing '\0'.
size_t pathsize = strlen(v) + 1 + sizeof(SYS_EXT_DIR) + sizeof("/lib/") + sizeof(DEFAULT_LIBPATH) + 1;
char *ld_library_path = NEW_C_HEAP_ARRAY(char, pathsize, mtInternal);
os::snprintf_checked(ld_library_path, pathsize, "%s%s" SYS_EXT_DIR "/lib:" DEFAULT_LIBPATH, v, v_colon);
Arguments::set_library_path(ld_library_path);
FREE_C_HEAP_ARRAY(char, ld_library_path);
}
// Extensions directories.
os::snprintf_checked(buf, bufsize, "%s" EXTENSIONS_DIR ":" SYS_EXT_DIR EXTENSIONS_DIR, Arguments::get_java_home());
Arguments::set_ext_dirs(buf);
FREE_C_HEAP_ARRAY(char, buf);
#undef DEFAULT_LIBPATH
#undef SYS_EXT_DIR
#undef EXTENSIONS_DIR
}
//////////////////////////////////////////////////////////////////////////////
// detecting pthread library
void os::Linux::libpthread_init() {
// Save glibc and pthread version strings.
#if !defined(_CS_GNU_LIBC_VERSION) || \
!defined(_CS_GNU_LIBPTHREAD_VERSION)
#error "glibc too old (< 2.3.2)"
#endif
#ifdef MUSL_LIBC
// confstr() from musl libc returns EINVAL for
// _CS_GNU_LIBC_VERSION and _CS_GNU_LIBPTHREAD_VERSION
os::Linux::set_libc_version("musl - unknown");
os::Linux::set_libpthread_version("musl - unknown");
#else
size_t n = confstr(_CS_GNU_LIBC_VERSION, nullptr, 0);
assert(n > 0, "cannot retrieve glibc version");
char *str = (char *)malloc(n, mtInternal);
confstr(_CS_GNU_LIBC_VERSION, str, n);
os::Linux::set_libc_version(str);
n = confstr(_CS_GNU_LIBPTHREAD_VERSION, nullptr, 0);
assert(n > 0, "cannot retrieve pthread version");
str = (char *)malloc(n, mtInternal);
confstr(_CS_GNU_LIBPTHREAD_VERSION, str, n);
os::Linux::set_libpthread_version(str);
#endif
}
/////////////////////////////////////////////////////////////////////////////
// thread stack expansion
// os::Linux::manually_expand_stack() takes care of expanding the thread
// stack. Note that this is normally not needed: pthread stacks allocate
// thread stack using mmap() without MAP_NORESERVE, so the stack is already
// committed. Therefore it is not necessary to expand the stack manually.
//
// Manually expanding the stack was historically needed on LinuxThreads
// thread stacks, which were allocated with mmap(MAP_GROWSDOWN). Nowadays
// it is kept to deal with very rare corner cases:
//
// For one, user may run the VM on an own implementation of threads
// whose stacks are - like the old LinuxThreads - implemented using
// mmap(MAP_GROWSDOWN).
//
// Also, this coding may be needed if the VM is running on the primordial
// thread. Normally we avoid running on the primordial thread; however,
// user may still invoke the VM on the primordial thread.
//
// The following historical comment describes the details about running
// on a thread stack allocated with mmap(MAP_GROWSDOWN):
// Force Linux kernel to expand current thread stack. If "bottom" is close
// to the stack guard, caller should block all signals.
//
// MAP_GROWSDOWN:
// A special mmap() flag that is used to implement thread stacks. It tells
// kernel that the memory region should extend downwards when needed. This
// allows early versions of LinuxThreads to only mmap the first few pages
// when creating a new thread. Linux kernel will automatically expand thread
// stack as needed (on page faults).
//
// However, because the memory region of a MAP_GROWSDOWN stack can grow on
// demand, if a page fault happens outside an already mapped MAP_GROWSDOWN
// region, it's hard to tell if the fault is due to a legitimate stack
// access or because of reading/writing non-exist memory (e.g. buffer
// overrun). As a rule, if the fault happens below current stack pointer,
// Linux kernel does not expand stack, instead a SIGSEGV is sent to the
// application (see Linux kernel fault.c).
//
// This Linux feature can cause SIGSEGV when VM bangs thread stack for
// stack overflow detection.
//
// Newer version of LinuxThreads (since glibc-2.2, or, RH-7.x) and NPTL do
// not use MAP_GROWSDOWN.
//
// To get around the problem and allow stack banging on Linux, we need to
// manually expand thread stack after receiving the SIGSEGV.
//
// There are two ways to expand thread stack to address "bottom", we used
// both of them in JVM before 1.5:
// 1. adjust stack pointer first so that it is below "bottom", and then
// touch "bottom"
// 2. mmap() the page in question
//
// Now alternate signal stack is gone, it's harder to use 2. For instance,
// if current sp is already near the lower end of page 101, and we need to
// call mmap() to map page 100, it is possible that part of the mmap() frame
// will be placed in page 100. When page 100 is mapped, it is zero-filled.
// That will destroy the mmap() frame and cause VM to crash.
//
// The following code works by adjusting sp first, then accessing the "bottom"
// page to force a page fault. Linux kernel will then automatically expand the
// stack mapping.
//
// _expand_stack_to() assumes its frame size is less than page size, which
// should always be true if the function is not inlined.
static void NOINLINE _expand_stack_to(address bottom) {
address sp;
size_t size;
volatile char *p;
// Adjust bottom to point to the largest address within the same page, it
// gives us a one-page buffer if alloca() allocates slightly more memory.
bottom = (address)align_down((uintptr_t)bottom, os::vm_page_size());
bottom += os::vm_page_size() - 1;
// sp might be slightly above current stack pointer; if that's the case, we
// will alloca() a little more space than necessary, which is OK. Don't use
// os::current_stack_pointer(), as its result can be slightly below current
// stack pointer, causing us to not alloca enough to reach "bottom".
sp = (address)&sp;
if (sp > bottom) {
size = sp - bottom;
p = (volatile char *)alloca(size);
assert(p != nullptr && p <= (volatile char *)bottom, "alloca problem?");
p[0] = '\0';
}
}
void os::Linux::expand_stack_to(address bottom) {
_expand_stack_to(bottom);
}
bool os::Linux::manually_expand_stack(JavaThread * t, address addr) {
assert(t!=nullptr, "just checking");
assert(t->osthread()->expanding_stack(), "expand should be set");
if (t->is_in_usable_stack(addr)) {
sigset_t mask_all, old_sigset;
sigfillset(&mask_all);
pthread_sigmask(SIG_SETMASK, &mask_all, &old_sigset);
_expand_stack_to(addr);
pthread_sigmask(SIG_SETMASK, &old_sigset, nullptr);
return true;
}
return false;
}
//////////////////////////////////////////////////////////////////////////////
// create new thread
// Thread start routine for all newly created threads
static void *thread_native_entry(Thread *thread) {
thread->record_stack_base_and_size();
#ifndef __GLIBC__
// Try to randomize the cache line index of hot stack frames.
// This helps when threads of the same stack traces evict each other's
// cache lines. The threads can be either from the same JVM instance, or
// from different JVM instances. The benefit is especially true for
// processors with hyperthreading technology.
// This code is not needed anymore in glibc because it has MULTI_PAGE_ALIASING
// and we did not see any degradation in performance without `alloca()`.
static int counter = 0;
int pid = os::current_process_id();
int random = ((pid ^ counter++) & 7) * 128;
void *stackmem = alloca(random != 0 ? random : 1); // ensure we allocate > 0
// Ensure the alloca result is used in a way that prevents the compiler from eliding it.
*(char *)stackmem = 1;
#endif
thread->initialize_thread_current();
OSThread* osthread = thread->osthread();
Monitor* sync = osthread->startThread_lock();
osthread->set_thread_id(checked_cast<pid_t>(os::current_thread_id()));
if (UseNUMA) {
int lgrp_id = os::numa_get_group_id();
if (lgrp_id != -1) {
thread->set_lgrp_id(lgrp_id);
}
}
// initialize signal mask for this thread
PosixSignals::hotspot_sigmask(thread);
// initialize floating point control register
os::Linux::init_thread_fpu_state();
// handshaking with parent thread
{
MutexLocker ml(sync, Mutex::_no_safepoint_check_flag);
// notify parent thread
osthread->set_state(INITIALIZED);
sync->notify_all();
// wait until os::start_thread()
while (osthread->get_state() == INITIALIZED) {
sync->wait_without_safepoint_check();
}
}
log_info(os, thread)("Thread is alive (tid: %zu, pthread id: %zu).",
os::current_thread_id(), (uintx) pthread_self());
assert(osthread->pthread_id() != 0, "pthread_id was not set as expected");
if (DelayThreadStartALot) {
os::naked_short_sleep(100);
}
// call one more level start routine
thread->call_run();
// Note: at this point the thread object may already have deleted itself.
// Prevent dereferencing it from here on out.
thread = nullptr;
log_info(os, thread)("Thread finished (tid: %zu, pthread id: %zu).",
os::current_thread_id(), (uintx) pthread_self());
return nullptr;
}
// On Linux, glibc places static TLS blocks (for __thread variables) on
// the thread stack. This decreases the stack size actually available
// to threads.
//
// For large static TLS sizes, this may cause threads to malfunction due
// to insufficient stack space. This is a well-known issue in glibc:
// http://sourceware.org/bugzilla/show_bug.cgi?id=11787.
//
// As a workaround, we call a private but assumed-stable glibc function,
// __pthread_get_minstack() to obtain the minstack size and derive the
// static TLS size from it. We then increase the user requested stack
// size by this TLS size. The same function is used to determine whether
// adjustStackSizeForGuardPages() needs to be true.
//
// Due to compatibility concerns, this size adjustment is opt-in and
// controlled via AdjustStackSizeForTLS.
typedef size_t (*GetMinStack)(const pthread_attr_t *attr);
GetMinStack _get_minstack_func = nullptr; // Initialized via os::init_2()
// Returns the size of the static TLS area glibc puts on thread stacks.
// The value is cached on first use, which occurs when the first thread
// is created during VM initialization.
static size_t get_static_tls_area_size(const pthread_attr_t *attr) {
size_t tls_size = 0;
if (_get_minstack_func != nullptr) {
// Obtain the pthread minstack size by calling __pthread_get_minstack.
size_t minstack_size = _get_minstack_func(attr);
// Remove non-TLS area size included in minstack size returned
// by __pthread_get_minstack() to get the static TLS size.
// If adjustStackSizeForGuardPages() is true, minstack size includes
// guard_size. Otherwise guard_size is automatically added
// to the stack size by pthread_create and is no longer included
// in minstack size. In both cases, the guard_size is taken into
// account, so there is no need to adjust the result for that.
//
// Although __pthread_get_minstack() is a private glibc function,
// it is expected to have a stable behavior across future glibc
// versions while glibc still allocates the static TLS blocks off
// the stack. Following is glibc 2.28 __pthread_get_minstack():
//
// size_t
// __pthread_get_minstack (const pthread_attr_t *attr)
// {
// return GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN;
// }
//
//
// The following 'minstack_size > os::vm_page_size() + PTHREAD_STACK_MIN'
// if check is done for precaution.
if (minstack_size > os::vm_page_size() + PTHREAD_STACK_MIN) {
tls_size = minstack_size - os::vm_page_size() - PTHREAD_STACK_MIN;
}
}
log_info(os, thread)("Stack size adjustment for TLS is %zu",
tls_size);
return tls_size;
}
// In glibc versions prior to 2.27 the guard size mechanism
// was not implemented properly. The POSIX standard requires adding
// the size of the guard pages to the stack size, instead glibc
// took the space out of 'stacksize'. Thus we need to adapt the requested
// stack_size by the size of the guard pages to mimic proper behaviour.
// The fix in glibc 2.27 has now been backported to numerous earlier
// glibc versions so we need to do a dynamic runtime check.
static bool _adjustStackSizeForGuardPages = true;
bool os::Linux::adjustStackSizeForGuardPages() {
return _adjustStackSizeForGuardPages;
}
#ifdef __GLIBC__
static void init_adjust_stacksize_for_guard_pages() {
assert(_get_minstack_func == nullptr, "initialization error");
_get_minstack_func =(GetMinStack)dlsym(RTLD_DEFAULT, "__pthread_get_minstack");
log_info(os, thread)("Lookup of __pthread_get_minstack %s",
_get_minstack_func == nullptr ? "failed" : "succeeded");
if (_get_minstack_func != nullptr) {
pthread_attr_t attr;
pthread_attr_init(&attr);
size_t min_stack = _get_minstack_func(&attr);
size_t guard = 16 * K; // Actual value doesn't matter as it is not examined
pthread_attr_setguardsize(&attr, guard);
size_t min_stack2 = _get_minstack_func(&attr);
pthread_attr_destroy(&attr);
// If the minimum stack size changed when we added the guard page space
// then we need to perform the adjustment.
_adjustStackSizeForGuardPages = (min_stack2 != min_stack);
log_info(os)("Glibc stack size guard page adjustment is %sneeded",
_adjustStackSizeForGuardPages ? "" : "not ");
}
}
#endif // GLIBC
bool os::create_thread(Thread* thread, ThreadType thr_type,
size_t req_stack_size) {
assert(thread->osthread() == nullptr, "caller responsible");
// Allocate the OSThread object
OSThread* osthread = new (std::nothrow) OSThread();
if (osthread == nullptr) {
return false;
}
// Initial state is ALLOCATED but not INITIALIZED
osthread->set_state(ALLOCATED);
thread->set_osthread(osthread);
// init thread attributes
pthread_attr_t attr;
int rslt = pthread_attr_init(&attr);
if (rslt != 0) {
thread->set_osthread(nullptr);
delete osthread;
return false;
}
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
// Calculate stack size if it's not specified by caller.
size_t stack_size = os::Posix::get_initial_stack_size(thr_type, req_stack_size);
size_t guard_size = os::Linux::default_guard_size(thr_type);
// Configure glibc guard page. Must happen before calling
// get_static_tls_area_size(), which uses the guard_size.
pthread_attr_setguardsize(&attr, guard_size);
// Apply stack size adjustments if needed. However, be careful not to end up
// with a size of zero due to overflow. Don't add the adjustment in that case.
size_t stack_adjust_size = 0;
if (AdjustStackSizeForTLS) {
// Adjust the stack_size for on-stack TLS - see get_static_tls_area_size().
stack_adjust_size += get_static_tls_area_size(&attr);
} else if (os::Linux::adjustStackSizeForGuardPages()) {
stack_adjust_size += guard_size;
}
stack_adjust_size = align_up(stack_adjust_size, os::vm_page_size());
if (stack_size <= SIZE_MAX - stack_adjust_size) {
stack_size += stack_adjust_size;
}
assert(is_aligned(stack_size, os::vm_page_size()), "stack_size not aligned");
if (THPStackMitigation) {
// In addition to the glibc guard page that prevents inter-thread-stack hugepage
// coalescing (see comment in os::Linux::default_guard_size()), we also make
// sure the stack size itself is not huge-page-size aligned; that makes it much
// more likely for thread stack boundaries to be unaligned as well and hence
// protects thread stacks from being targeted by khugepaged.
if (HugePages::thp_pagesize() > 0 &&
is_aligned(stack_size, HugePages::thp_pagesize())) {
stack_size += os::vm_page_size();
}
}
int status = pthread_attr_setstacksize(&attr, stack_size);
if (status != 0) {
// pthread_attr_setstacksize() function can fail
// if the stack size exceeds a system-imposed limit.
assert_status(status == EINVAL, status, "pthread_attr_setstacksize");
log_warning(os, thread)("The %sthread stack size specified is invalid: %zuk",
(thr_type == compiler_thread) ? "compiler " : ((thr_type == java_thread) ? "" : "VM "),
stack_size / K);
thread->set_osthread(nullptr);
delete osthread;
pthread_attr_destroy(&attr);
return false;
}
ThreadState state;
{
ResourceMark rm;
pthread_t tid;
int ret = 0;
int trials_remaining = 4;
useconds_t next_delay = 1000;
while (true) {
ret = pthread_create(&tid, &attr, (void* (*)(void*)) thread_native_entry, thread);
if (ret != EAGAIN) {
break;
}
if (--trials_remaining <= 0) {
break;
}
log_debug(os, thread)("Failed to start native thread (%s), retrying after %dus.", os::errno_name(ret), next_delay);
::usleep(next_delay);
next_delay *= 2;
}
char buf[64];
if (ret == 0) {
log_info(os, thread)("Thread \"%s\" started (pthread id: %zu, attributes: %s). ",
thread->name(), (uintx) tid, os::Posix::describe_pthread_attr(buf, sizeof(buf), &attr));
// Print current timer slack if override is enabled and timer slack value is available.
// Avoid calling prctl otherwise for extra safety.
if (TimerSlack >= 0) {
int slack = prctl(PR_GET_TIMERSLACK);
if (slack >= 0) {
log_info(os, thread)("Thread \"%s\" (pthread id: %zu) timer slack: %dns",
thread->name(), (uintx) tid, slack);
}
}
} else {
log_warning(os, thread)("Failed to start thread \"%s\" - pthread_create failed (%s) for attributes: %s.",
thread->name(), os::errno_name(ret), os::Posix::describe_pthread_attr(buf, sizeof(buf), &attr));
// Log some OS information which might explain why creating the thread failed.
log_info(os, thread)("Number of threads approx. running in the VM: %d", Threads::number_of_threads());
LogStream st(Log(os, thread)::info());
os::Posix::print_rlimit_info(&st);
os::print_memory_info(&st);
os::Linux::print_proc_sys_info(&st);
os::Linux::print_container_info(&st);
}
pthread_attr_destroy(&attr);
if (ret != 0) {
// Need to clean up stuff we've allocated so far
thread->set_osthread(nullptr);
delete osthread;
return false;
}
// Store pthread info into the OSThread
osthread->set_pthread_id(tid);
// Wait until child thread is either initialized or aborted
{
Monitor* sync_with_child = osthread->startThread_lock();
MutexLocker ml(sync_with_child, Mutex::_no_safepoint_check_flag);
while ((state = osthread->get_state()) == ALLOCATED) {
sync_with_child->wait_without_safepoint_check();
}
}
}
// The thread is returned suspended (in state INITIALIZED),
// and is started higher up in the call chain
assert(state == INITIALIZED, "race condition");
return true;
}
/////////////////////////////////////////////////////////////////////////////
// attach existing thread
// bootstrap the main thread
bool os::create_main_thread(JavaThread* thread) {
assert(os::Linux::_main_thread == pthread_self(), "should be called inside main thread");
return create_attached_thread(thread);
}
bool os::create_attached_thread(JavaThread* thread) {
#ifdef ASSERT
thread->verify_not_published();
#endif
// Allocate the OSThread object
OSThread* osthread = new (std::nothrow) OSThread();
if (osthread == nullptr) {
return false;
}
// Store pthread info into the OSThread
osthread->set_thread_id(os::Linux::gettid());
osthread->set_pthread_id(::pthread_self());
// initialize floating point control register
os::Linux::init_thread_fpu_state();
// Initial thread state is RUNNABLE
osthread->set_state(RUNNABLE);
thread->set_osthread(osthread);
if (UseNUMA) {
int lgrp_id = os::numa_get_group_id();
if (lgrp_id != -1) {
thread->set_lgrp_id(lgrp_id);
}
}
if (os::is_primordial_thread()) {
// If current thread is primordial thread, its stack is mapped on demand,
// see notes about MAP_GROWSDOWN. Here we try to force kernel to map
// the entire stack region to avoid SEGV in stack banging.
// It is also useful to get around the heap-stack-gap problem on SuSE
// kernel (see 4821821 for details). We first expand stack to the top
// of yellow zone, then enable stack yellow zone (order is significant,
// enabling yellow zone first will crash JVM on SuSE Linux), so there
// is no gap between the last two virtual memory regions.
StackOverflow* overflow_state = thread->stack_overflow_state();
address addr = overflow_state->stack_reserved_zone_base();
assert(addr != nullptr, "initialization problem?");
assert(overflow_state->stack_available(addr) > 0, "stack guard should not be enabled");
osthread->set_expanding_stack();
os::Linux::manually_expand_stack(thread, addr);
osthread->clear_expanding_stack();
}
// initialize signal mask for this thread
// and save the caller's signal mask
PosixSignals::hotspot_sigmask(thread);
log_info(os, thread)("Thread attached (tid: %zu, pthread id: %zu"
", stack: " PTR_FORMAT " - " PTR_FORMAT " (%zuK) ).",
os::current_thread_id(), (uintx) pthread_self(),
p2i(thread->stack_base()), p2i(thread->stack_end()), thread->stack_size() / K);
return true;
}
void os::pd_start_thread(Thread* thread) {
OSThread * osthread = thread->osthread();
assert(osthread->get_state() != INITIALIZED, "just checking");
Monitor* sync_with_child = osthread->startThread_lock();
MutexLocker ml(sync_with_child, Mutex::_no_safepoint_check_flag);
sync_with_child->notify();
}
// Free Linux resources related to the OSThread
void os::free_thread(OSThread* osthread) {
assert(osthread != nullptr, "osthread not set");
// We are told to free resources of the argument thread, but we can only really operate
// on the current thread. The current thread may be already detached at this point.
assert(Thread::current_or_null() == nullptr || Thread::current()->osthread() == osthread,
"os::free_thread but not current thread");
#ifdef ASSERT
sigset_t current;
sigemptyset(&current);
pthread_sigmask(SIG_SETMASK, nullptr, &current);
assert(!sigismember(&current, PosixSignals::SR_signum), "SR signal should not be blocked!");
#endif
// Restore caller's signal mask
sigset_t sigmask = osthread->caller_sigmask();
pthread_sigmask(SIG_SETMASK, &sigmask, nullptr);
delete osthread;
}
//////////////////////////////////////////////////////////////////////////////
// primordial thread
// Check if current thread is the primordial thread, similar to Solaris thr_main.
bool os::is_primordial_thread(void) {
if (suppress_primordial_thread_resolution) {
return false;
}
char dummy;
// If called before init complete, thread stack bottom will be null.
// Can be called if fatal error occurs before initialization.
if (os::Linux::initial_thread_stack_bottom() == nullptr) return false;
assert(os::Linux::initial_thread_stack_bottom() != nullptr &&
os::Linux::initial_thread_stack_size() != 0,
"os::init did not locate primordial thread's stack region");
if ((address)&dummy >= os::Linux::initial_thread_stack_bottom() &&
(address)&dummy < os::Linux::initial_thread_stack_bottom() +
os::Linux::initial_thread_stack_size()) {
return true;
} else {
return false;
}
}
// Find the virtual memory area that contains addr
static bool find_vma(address addr, address* vma_low, address* vma_high) {
FILE *fp = os::fopen("/proc/self/maps", "r");
if (fp) {
address low, high;
while (!feof(fp)) {
if (fscanf(fp, "%p-%p", &low, &high) == 2) {
if (low <= addr && addr < high) {
if (vma_low) *vma_low = low;
if (vma_high) *vma_high = high;
fclose(fp);
return true;
}
}
for (;;) {
int ch = fgetc(fp);
if (ch == EOF || ch == (int)'\n') break;
}
}
fclose(fp);
}
return false;
}
// Locate primordial thread stack. This special handling of primordial thread stack
// is needed because pthread_getattr_np() on most (all?) Linux distros returns
// bogus value for the primordial process thread. While the launcher has created
// the VM in a new thread since JDK 6, we still have to allow for the use of the
// JNI invocation API from a primordial thread.
void os::Linux::capture_initial_stack(size_t max_size) {
// max_size is either 0 (which means accept OS default for thread stacks) or
// a user-specified value known to be at least the minimum needed. If we
// are actually on the primordial thread we can make it appear that we have a
// smaller max_size stack by inserting the guard pages at that location. But we
// cannot do anything to emulate a larger stack than what has been provided by
// the OS or threading library. In fact if we try to use a stack greater than
// what is set by rlimit then we will crash the hosting process.
// Maximum stack size is the easy part, get it from RLIMIT_STACK.
// If this is "unlimited" then it will be a huge value.
struct rlimit rlim;
getrlimit(RLIMIT_STACK, &rlim);
size_t stack_size = rlim.rlim_cur;
// 6308388: a bug in ld.so will relocate its own .data section to the
// lower end of primordial stack; reduce ulimit -s value a little bit
// so we won't install guard page on ld.so's data section.
// But ensure we don't underflow the stack size - allow 1 page spare
if (stack_size >= 3 * os::vm_page_size()) {
stack_size -= 2 * os::vm_page_size();
}
// Try to figure out where the stack base (top) is. This is harder.
//
// When an application is started, glibc saves the initial stack pointer in
// a global variable "__libc_stack_end", which is then used by system
// libraries. __libc_stack_end should be pretty close to stack top. The
// variable is available since the very early days. However, because it is
// a private interface, it could disappear in the future.
//
// Linux kernel saves start_stack information in /proc/<pid>/stat. Similar
// to __libc_stack_end, it is very close to stack top, but isn't the real
// stack top. Note that /proc may not exist if VM is running as a chroot
// program, so reading /proc/<pid>/stat could fail. Also the contents of
// /proc/<pid>/stat could change in the future (though unlikely).
//
// We try __libc_stack_end first. If that doesn't work, look for
// /proc/<pid>/stat. If neither of them works, we use current stack pointer
// as a hint, which should work well in most cases.
uintptr_t stack_start;
// try __libc_stack_end first
uintptr_t *p = (uintptr_t *)dlsym(RTLD_DEFAULT, "__libc_stack_end");
if (p && *p) {
stack_start = *p;
} else {
// see if we can get the start_stack field from /proc/self/stat
FILE *fp;
int pid;
char state;
int ppid;
int pgrp;
int session;
int nr;
int tpgrp;
unsigned long flags;
unsigned long minflt;
unsigned long cminflt;
unsigned long majflt;
unsigned long cmajflt;
unsigned long utime;
unsigned long stime;
long cutime;
long cstime;
long prio;
long nice;
long junk;
long it_real;
uintptr_t start;
uintptr_t vsize;
intptr_t rss;
uintptr_t rsslim;
uintptr_t scodes;
uintptr_t ecode;
int i;
// Figure what the primordial thread stack base is. Code is inspired
// by email from Hans Boehm. /proc/self/stat begins with current pid,
// followed by command name surrounded by parentheses, state, etc.
char stat[2048];
size_t statlen;
fp = os::fopen("/proc/self/stat", "r");
if (fp) {
statlen = fread(stat, 1, 2047, fp);
stat[statlen] = '\0';
fclose(fp);
// Skip pid and the command string. Note that we could be dealing with
// weird command names, e.g. user could decide to rename java launcher
// to "java 1.4.2 :)", then the stat file would look like
// 1234 (java 1.4.2 :)) R ... ...
// We don't really need to know the command string, just find the last
// occurrence of ")" and then start parsing from there. See bug 4726580.
char * s = strrchr(stat, ')');
i = 0;
if (s) {
// Skip blank chars
do { s++; } while (s && isspace((unsigned char) *s));
// 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
// 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8
i = sscanf(s, "%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu %ld %ld %ld %ld %ld %ld %zu %zu %zd %zu %zu %zu %zu",
&state, // 3 %c
&ppid, // 4 %d
&pgrp, // 5 %d
&session, // 6 %d
&nr, // 7 %d
&tpgrp, // 8 %d
&flags, // 9 %lu
&minflt, // 10 %lu
&cminflt, // 11 %lu
&majflt, // 12 %lu
&cmajflt, // 13 %lu
&utime, // 14 %lu
&stime, // 15 %lu
&cutime, // 16 %ld
&cstime, // 17 %ld
&prio, // 18 %ld
&nice, // 19 %ld
&junk, // 20 %ld
&it_real, // 21 %ld
&start, // 22 %zu
&vsize, // 23 %zu
&rss, // 24 %zd
&rsslim, // 25 %zu
&scodes, // 26 %zu
&ecode, // 27 %zu
&stack_start); // 28 %zu
}
if (i != 28 - 2) {
assert(false, "Bad conversion from /proc/self/stat");
// product mode - assume we are the primordial thread, good luck in the
// embedded case.
warning("Can't detect primordial thread stack location - bad conversion");
stack_start = (uintptr_t) &rlim;
}
} else {
// For some reason we can't open /proc/self/stat (for example, running on
// FreeBSD with a Linux emulator, or inside chroot), this should work for
// most cases, so don't abort:
warning("Can't detect primordial thread stack location - no /proc/self/stat");
stack_start = (uintptr_t) &rlim;
}
}
// Now we have a pointer (stack_start) very close to the stack top, the
// next thing to do is to figure out the exact location of stack top. We
// can find out the virtual memory area that contains stack_start by
// reading /proc/self/maps, it should be the last vma in /proc/self/maps,
// and its upper limit is the real stack top. (again, this would fail if
// running inside chroot, because /proc may not exist.)
uintptr_t stack_top;
address low, high;
if (find_vma((address)stack_start, &low, &high)) {
// success, "high" is the true stack top. (ignore "low", because initial
// thread stack grows on demand, its real bottom is high - RLIMIT_STACK.)
stack_top = (uintptr_t)high;
} else {
// failed, likely because /proc/self/maps does not exist
warning("Can't detect primordial thread stack location - find_vma failed");
// best effort: stack_start is normally within a few pages below the real
// stack top, use it as stack top, and reduce stack size so we won't put
// guard page outside stack.
stack_top = stack_start;
stack_size -= 16 * os::vm_page_size();
}
// stack_top could be partially down the page so align it
stack_top = align_up(stack_top, os::vm_page_size());
// Allowed stack value is minimum of max_size and what we derived from rlimit
if (max_size > 0) {
_initial_thread_stack_size = MIN2(max_size, stack_size);
} else {
// Accept the rlimit max, but if stack is unlimited then it will be huge, so
// clamp it at 8MB as we do on Solaris
_initial_thread_stack_size = MIN2(stack_size, 8*M);
}
_initial_thread_stack_size = align_down(_initial_thread_stack_size, os::vm_page_size());
_initial_thread_stack_bottom = (address)stack_top - _initial_thread_stack_size;
assert(_initial_thread_stack_bottom < (address)stack_top, "overflow!");
if (log_is_enabled(Info, os, thread)) {
// See if we seem to be on primordial process thread
bool primordial = uintptr_t(&rlim) > uintptr_t(_initial_thread_stack_bottom) &&
uintptr_t(&rlim) < stack_top;
log_info(os, thread)("Capturing initial stack in %s thread: req. size: %zuK, actual size: "
"%zuK, top=" INTPTR_FORMAT ", bottom=" INTPTR_FORMAT,
primordial ? "primordial" : "user", max_size / K, _initial_thread_stack_size / K,
stack_top, intptr_t(_initial_thread_stack_bottom));
}
}
////////////////////////////////////////////////////////////////////////////////
// time support
double os::elapsedVTime() {
struct rusage usage;
int retval = getrusage(RUSAGE_THREAD, &usage);
if (retval == 0) {
return (double) (usage.ru_utime.tv_sec + usage.ru_stime.tv_sec) + (double) (usage.ru_utime.tv_usec + usage.ru_stime.tv_usec) / (1000 * 1000);
} else {
// better than nothing, but not much
return elapsedTime();
}
}
void os::Linux::fast_thread_clock_init() {
clockid_t clockid;
struct timespec tp;
int (*pthread_getcpuclockid_func)(pthread_t, clockid_t *) =
(int(*)(pthread_t, clockid_t *)) dlsym(RTLD_DEFAULT, "pthread_getcpuclockid");
// Switch to using fast clocks for thread cpu time if
// the clock_getres() returns 0 error code.
// Note, that some kernels may support the current thread
// clock (CLOCK_THREAD_CPUTIME_ID) but not the clocks
// returned by the pthread_getcpuclockid().
// If the fast POSIX clocks are supported then the clock_getres()
// must return at least tp.tv_sec == 0 which means a resolution
// better than 1 sec. This is extra check for reliability.
if (pthread_getcpuclockid_func &&
pthread_getcpuclockid_func(_main_thread, &clockid) == 0 &&
clock_getres(clockid, &tp) == 0 && tp.tv_sec == 0) {
_supports_fast_thread_cpu_time = true;
_pthread_getcpuclockid = pthread_getcpuclockid_func;
}
}
// thread_id is kernel thread id (similar to Solaris LWP id)
intx os::current_thread_id() { return os::Linux::gettid(); }
int os::current_process_id() {
return ::getpid();
}
// DLL functions
// This must be hard coded because it's the system's temporary
// directory not the java application's temp directory, ala java.io.tmpdir.
const char* os::get_temp_directory() { return "/tmp"; }
// check if addr is inside libjvm.so
bool os::address_is_in_vm(address addr) {
static address libjvm_base_addr;
Dl_info dlinfo;
if (libjvm_base_addr == nullptr) {
if (dladdr(CAST_FROM_FN_PTR(void *, os::address_is_in_vm), &dlinfo) != 0) {
libjvm_base_addr = (address)dlinfo.dli_fbase;
}
assert(libjvm_base_addr !=nullptr, "Cannot obtain base address for libjvm");
}
if (dladdr((void *)addr, &dlinfo) != 0) {
if (libjvm_base_addr == (address)dlinfo.dli_fbase) return true;
}
return false;
}
void os::prepare_native_symbols() {
}
bool os::dll_address_to_function_name(address addr, char *buf,
int buflen, int *offset,
bool demangle) {
// buf is not optional, but offset is optional
assert(buf != nullptr, "sanity check");
Dl_info dlinfo;
if (dladdr((void*)addr, &dlinfo) != 0) {
// see if we have a matching symbol
if (dlinfo.dli_saddr != nullptr && dlinfo.dli_sname != nullptr) {
if (!(demangle && Decoder::demangle(dlinfo.dli_sname, buf, buflen))) {
jio_snprintf(buf, buflen, "%s", dlinfo.dli_sname);
}
if (offset != nullptr) *offset = pointer_delta_as_int(addr, (address)dlinfo.dli_saddr);
return true;
}
// no matching symbol so try for just file info
if (dlinfo.dli_fname != nullptr && dlinfo.dli_fbase != nullptr) {
if (Decoder::decode((address)(addr - (address)dlinfo.dli_fbase),
buf, buflen, offset, dlinfo.dli_fname, demangle)) {
return true;
}
}
}
buf[0] = '\0';
if (offset != nullptr) *offset = -1;
return false;
}
bool os::dll_address_to_library_name(address addr, char* buf,
int buflen, int* offset) {
// buf is not optional, but offset is optional
assert(buf != nullptr, "sanity check");
Dl_info dlinfo;
if (dladdr((void*)addr, &dlinfo) != 0) {
if (dlinfo.dli_fname != nullptr) {
jio_snprintf(buf, buflen, "%s", dlinfo.dli_fname);
}
if (dlinfo.dli_fbase != nullptr && offset != nullptr) {
*offset = pointer_delta_as_int(addr, (address)dlinfo.dli_fbase);
}
return true;
}
buf[0] = '\0';
if (offset) *offset = -1;
return false;
}
// Remember the stack's state. The Linux dynamic linker will change
// the stack to 'executable' at most once, so we must safepoint only once.
bool os::Linux::_stack_is_executable = false;
// VM operation that loads a library. This is necessary if stack protection
// of the Java stacks can be lost during loading the library. If we
// do not stop the Java threads, they can stack overflow before the stacks
// are protected again.
class VM_LinuxDllLoad: public VM_Operation {
private:
const char *_filename;
char *_ebuf;
int _ebuflen;
void *_lib;
public:
VM_LinuxDllLoad(const char *fn, char *ebuf, int ebuflen) :
_filename(fn), _ebuf(ebuf), _ebuflen(ebuflen), _lib(nullptr) {}
VMOp_Type type() const { return VMOp_LinuxDllLoad; }
void doit() {
_lib = os::Linux::dll_load_in_vmthread(_filename, _ebuf, _ebuflen);
os::Linux::_stack_is_executable = true;
}
void* loaded_library() { return _lib; }
};
void * os::dll_load(const char *filename, char *ebuf, int ebuflen) {
void * result = nullptr;
bool load_attempted = false;
log_info(os)("attempting shared library load of %s", filename);
// Check whether the library to load might change execution rights
// of the stack. If they are changed, the protection of the stack
// guard pages will be lost. We need a safepoint to fix this.
//
// See Linux man page execstack(8) for more info.
if (os::uses_stack_guard_pages() && !os::Linux::_stack_is_executable) {
if (!ElfFile::specifies_noexecstack(filename)) {
if (!is_init_completed()) {
os::Linux::_stack_is_executable = true;
// This is OK - No Java threads have been created yet, and hence no
// stack guard pages to fix.
//
// Dynamic loader will make all stacks executable after
// this function returns, and will not do that again.
assert(Threads::number_of_threads() == 0, "no Java threads should exist yet.");
} else {
warning("You have loaded library %s which might have disabled stack guard. "
"The VM will try to fix the stack guard now.\n"
"It's highly recommended that you fix the library with "
"'execstack -c <libfile>', or link it with '-z noexecstack'.",
filename);
JavaThread *jt = JavaThread::current();
if (jt->thread_state() != _thread_in_native) {
// This happens when a compiler thread tries to load a hsdis-<arch>.so file
// that requires ExecStack. Cannot enter safe point. Let's give up.
warning("Unable to fix stack guard. Giving up.");
} else {
if (!LoadExecStackDllInVMThread) {
// This is for the case where the DLL has an static
// constructor function that executes JNI code. We cannot
// load such DLLs in the VMThread.
result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
}
ThreadInVMfromNative tiv(jt);
DEBUG_ONLY(VMNativeEntryWrapper vew;)
VM_LinuxDllLoad op(filename, ebuf, ebuflen);
VMThread::execute(&op);
if (LoadExecStackDllInVMThread) {
result = op.loaded_library();
}
load_attempted = true;
}
}
}
}
if (!load_attempted) {
result = os::Linux::dlopen_helper(filename, ebuf, ebuflen);
}
if (result != nullptr) {
// Successful loading
return result;
}
Elf32_Ehdr elf_head;
size_t prefix_len = strlen(ebuf);
ssize_t diag_msg_max_length = ebuflen - prefix_len;
if (diag_msg_max_length <= 0) {
// No more space in ebuf for additional diagnostics message
return nullptr;
}
char* diag_msg_buf = ebuf + prefix_len;
int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
if (file_descriptor < 0) {
// Can't open library, report dlerror() message
return nullptr;
}
bool failed_to_read_elf_head=
(sizeof(elf_head)!=
(::read(file_descriptor, &elf_head,sizeof(elf_head))));
::close(file_descriptor);
if (failed_to_read_elf_head) {
// file i/o error - report dlerror() msg
return nullptr;
}
if (elf_head.e_ident[EI_DATA] != LITTLE_ENDIAN_ONLY(ELFDATA2LSB) BIG_ENDIAN_ONLY(ELFDATA2MSB)) {
// handle invalid/out of range endianness values
if (elf_head.e_ident[EI_DATA] == 0 || elf_head.e_ident[EI_DATA] > 2) {
return nullptr;
}
#if defined(VM_LITTLE_ENDIAN)
// VM is LE, shared object BE
elf_head.e_machine = be16toh(elf_head.e_machine);
#else
// VM is BE, shared object LE
elf_head.e_machine = le16toh(elf_head.e_machine);
#endif
}
typedef struct {
Elf32_Half code; // Actual value as defined in elf.h
Elf32_Half compat_class; // Compatibility of archs at VM's sense
unsigned char elf_class; // 32 or 64 bit
unsigned char endianness; // MSB or LSB
char* name; // String representation
} arch_t;
#ifndef EM_AARCH64
#define EM_AARCH64 183 /* ARM AARCH64 */
#endif
#ifndef EM_RISCV
#define EM_RISCV 243 /* RISC-V */
#endif
#ifndef EM_LOONGARCH
#define EM_LOONGARCH 258 /* LoongArch */
#endif
static const arch_t arch_array[]={
{EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
{EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
{EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
{EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
{EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
{EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
{EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
{EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
#if defined(VM_LITTLE_ENDIAN)
{EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2LSB, (char*)"Power PC 64 LE"},
{EM_SH, EM_SH, ELFCLASS32, ELFDATA2LSB, (char*)"SuperH"},
#else
{EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
{EM_SH, EM_SH, ELFCLASS32, ELFDATA2MSB, (char*)"SuperH BE"},
#endif
{EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
// we only support 64 bit z architecture
{EM_S390, EM_S390, ELFCLASS64, ELFDATA2MSB, (char*)"IBM System/390"},
{EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
{EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
{EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
{EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
{EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"},
{EM_AARCH64, EM_AARCH64, ELFCLASS64, ELFDATA2LSB, (char*)"AARCH64"},
#ifdef _LP64
{EM_RISCV, EM_RISCV, ELFCLASS64, ELFDATA2LSB, (char*)"RISCV64"},
#else
{EM_RISCV, EM_RISCV, ELFCLASS32, ELFDATA2LSB, (char*)"RISCV32"},
#endif
{EM_LOONGARCH, EM_LOONGARCH, ELFCLASS64, ELFDATA2LSB, (char*)"LoongArch"},
};
#if (defined IA32)
static Elf32_Half running_arch_code=EM_386;
#elif (defined AMD64) || (defined X32)
static Elf32_Half running_arch_code=EM_X86_64;
#elif (defined __sparc) && (defined _LP64)
static Elf32_Half running_arch_code=EM_SPARCV9;
#elif (defined __sparc) && (!defined _LP64)
static Elf32_Half running_arch_code=EM_SPARC;
#elif (defined __powerpc64__)
static Elf32_Half running_arch_code=EM_PPC64;
#elif (defined __powerpc__)
static Elf32_Half running_arch_code=EM_PPC;
#elif (defined AARCH64)
static Elf32_Half running_arch_code=EM_AARCH64;
#elif (defined ARM)
static Elf32_Half running_arch_code=EM_ARM;
#elif (defined S390)
static Elf32_Half running_arch_code=EM_S390;
#elif (defined ALPHA)
static Elf32_Half running_arch_code=EM_ALPHA;
#elif (defined MIPSEL)
static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
#elif (defined PARISC)
static Elf32_Half running_arch_code=EM_PARISC;
#elif (defined MIPS)
static Elf32_Half running_arch_code=EM_MIPS;
#elif (defined M68K)
static Elf32_Half running_arch_code=EM_68K;
#elif (defined SH)
static Elf32_Half running_arch_code=EM_SH;
#elif (defined RISCV)
static Elf32_Half running_arch_code=EM_RISCV;
#elif (defined LOONGARCH64)
static Elf32_Half running_arch_code=EM_LOONGARCH;
#else
#error Method os::dll_load requires that one of following is defined:\
AARCH64, ALPHA, ARM, AMD64, IA32, LOONGARCH64, M68K, MIPS, MIPSEL, PARISC, __powerpc__, __powerpc64__, RISCV, S390, SH, __sparc
#endif
// Identify compatibility class for VM's architecture and library's architecture
// Obtain string descriptions for architectures
arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], nullptr};
int running_arch_index=-1;
for (unsigned int i=0; i < ARRAY_SIZE(arch_array); i++) {
if (running_arch_code == arch_array[i].code) {
running_arch_index = i;
}
if (lib_arch.code == arch_array[i].code) {
lib_arch.compat_class = arch_array[i].compat_class;
lib_arch.name = arch_array[i].name;
}
}
assert(running_arch_index != -1,
"Didn't find running architecture code (running_arch_code) in arch_array");
if (running_arch_index == -1) {
// Even though running architecture detection failed
// we may still continue with reporting dlerror() message
return nullptr;
}
if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
if (lib_arch.name != nullptr) {
::snprintf(diag_msg_buf, diag_msg_max_length-1,
" (Possible cause: can't load %s .so on a %s platform)",
lib_arch.name, arch_array[running_arch_index].name);
} else {
::snprintf(diag_msg_buf, diag_msg_max_length-1,
" (Possible cause: can't load this .so (machine code=0x%x) on a %s platform)",
lib_arch.code, arch_array[running_arch_index].name);
}
return nullptr;
}
if (lib_arch.endianness != arch_array[running_arch_index].endianness) {
::snprintf(diag_msg_buf, diag_msg_max_length-1, " (Possible cause: endianness mismatch)");
return nullptr;
}
// ELF file class/capacity : 0 - invalid, 1 - 32bit, 2 - 64bit
if (lib_arch.elf_class > 2 || lib_arch.elf_class < 1) {
::snprintf(diag_msg_buf, diag_msg_max_length-1, " (Possible cause: invalid ELF file class)");
return nullptr;
}
if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
::snprintf(diag_msg_buf, diag_msg_max_length-1,
" (Possible cause: architecture word width mismatch, can't load %d-bit .so on a %d-bit platform)",
(int) lib_arch.elf_class * 32, arch_array[running_arch_index].elf_class * 32);
return nullptr;
}
return nullptr;
}
void * os::Linux::dlopen_helper(const char *filename, char *ebuf, int ebuflen) {
#ifndef IA32
bool ieee_handling = IEEE_subnormal_handling_OK();
if (!ieee_handling) {
Events::log_dll_message(nullptr, "IEEE subnormal handling check failed before loading %s", filename);
log_info(os)("IEEE subnormal handling check failed before loading %s", filename);
if (CheckJNICalls) {
tty->print_cr("WARNING: IEEE subnormal handling check failed before loading %s", filename);
Thread* current = Thread::current();
if (current->is_Java_thread()) {
JavaThread::cast(current)->print_jni_stack();
}
}
}
// Save and restore the floating-point environment around dlopen().
// There are known cases where global library initialization sets
// FPU flags that affect computation accuracy, for example, enabling
// Flush-To-Zero and Denormals-Are-Zero. Do not let those libraries
// break Java arithmetic. Unfortunately, this might affect libraries
// that might depend on these FPU features for performance and/or
// numerical "accuracy", but we need to protect Java semantics first
// and foremost. See JDK-8295159.
// This workaround is ineffective on IA32 systems because the MXCSR
// register (which controls flush-to-zero mode) is not stored in the
// legacy fenv.
fenv_t default_fenv;
int rtn = fegetenv(&default_fenv);
assert(rtn == 0, "fegetenv must succeed");
#endif // IA32
void* result;
JFR_ONLY(NativeLibraryLoadEvent load_event(filename, &result);)
result = ::dlopen(filename, RTLD_LAZY);
if (result == nullptr) {
const char* error_report = ::dlerror();
if (error_report == nullptr) {
error_report = "dlerror returned no error description";
}
if (ebuf != nullptr && ebuflen > 0) {
::strncpy(ebuf, error_report, ebuflen-1);
ebuf[ebuflen-1]='\0';
}
Events::log_dll_message(nullptr, "Loading shared library %s failed, %s", filename, error_report);
log_info(os)("shared library load of %s failed, %s", filename, error_report);
JFR_ONLY(load_event.set_error_msg(error_report);)
} else {
Events::log_dll_message(nullptr, "Loaded shared library %s", filename);
log_info(os)("shared library load of %s was successful", filename);
#ifndef IA32
// Quickly test to make sure subnormals are correctly handled.
if (! IEEE_subnormal_handling_OK()) {
// We just dlopen()ed a library that mangled the floating-point flags.
// Attempt to fix things now.
JFR_ONLY(load_event.set_fp_env_correction_attempt(true);)
int rtn = fesetenv(&default_fenv);
assert(rtn == 0, "fesetenv must succeed");
if (IEEE_subnormal_handling_OK()) {
Events::log_dll_message(nullptr, "IEEE subnormal handling had to be corrected after loading %s", filename);
log_info(os)("IEEE subnormal handling had to be corrected after loading %s", filename);
JFR_ONLY(load_event.set_fp_env_correction_success(true);)
} else {
Events::log_dll_message(nullptr, "IEEE subnormal handling could not be corrected after loading %s", filename);
log_info(os)("IEEE subnormal handling could not be corrected after loading %s", filename);
if (CheckJNICalls) {
tty->print_cr("WARNING: IEEE subnormal handling could not be corrected after loading %s", filename);
Thread* current = Thread::current();
if (current->is_Java_thread()) {
JavaThread::cast(current)->print_jni_stack();
}
}
assert(false, "fesetenv didn't work");
}
}
#endif // IA32
}
return result;
}
void * os::Linux::dll_load_in_vmthread(const char *filename, char *ebuf,
int ebuflen) {
void * result = nullptr;
if (LoadExecStackDllInVMThread) {
result = dlopen_helper(filename, ebuf, ebuflen);
}
// Since 7019808, libjvm.so is linked with -noexecstack. If the VM loads a
// library that requires an executable stack, or which does not have this
// stack attribute set, dlopen changes the stack attribute to executable. The
// read protection of the guard pages gets lost.
//
// Need to check _stack_is_executable again as multiple VM_LinuxDllLoad
// may have been queued at the same time.
if (!_stack_is_executable) {
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
StackOverflow* overflow_state = jt->stack_overflow_state();
if (!overflow_state->stack_guard_zone_unused() && // Stack not yet fully initialized
overflow_state->stack_guards_enabled()) { // No pending stack overflow exceptions
if (!os::guard_memory((char *)jt->stack_end(), StackOverflow::stack_guard_zone_size())) {
warning("Attempt to reguard stack yellow zone failed.");
}
}
}
}
return result;
}
const char* os::Linux::dll_path(void* lib) {
struct link_map *lmap;
const char* l_path = nullptr;
assert(lib != nullptr, "dll_path parameter must not be null");
int res_dli = ::dlinfo(lib, RTLD_DI_LINKMAP, &lmap);
if (res_dli == 0) {
l_path = lmap->l_name;
}
return l_path;
}
static unsigned count_newlines(const char* s) {
unsigned n = 0;
for (const char* s2 = strchr(s, '\n');
s2 != nullptr; s2 = strchr(s2 + 1, '\n')) {
n++;
}
return n;
}
static bool _print_ascii_file(const char* filename, outputStream* st, unsigned* num_lines = nullptr, const char* hdr = nullptr) {
int fd = ::open(filename, O_RDONLY);
if (fd == -1) {
return false;
}
if (hdr != nullptr) {
st->print_cr("%s", hdr);
}
char buf[33];
ssize_t bytes;
buf[32] = '\0';
unsigned lines = 0;
while ((bytes = ::read(fd, buf, sizeof(buf)-1)) > 0) {
st->print_raw(buf, bytes);
// count newlines
if (num_lines != nullptr) {
lines += count_newlines(buf);
}
}
if (num_lines != nullptr) {
(*num_lines) = lines;
}
::close(fd);
return true;
}
static void _print_ascii_file_h(const char* header, const char* filename, outputStream* st, bool same_line = true) {
st->print("%s:%c", header, same_line ? ' ' : '\n');
if (!_print_ascii_file(filename, st)) {
st->print_cr("<Not Available>");
}
}
void os::print_dll_info(outputStream *st) {
st->print_cr("Dynamic libraries:");
char fname[32];
pid_t pid = os::Linux::gettid();
jio_snprintf(fname, sizeof(fname), "/proc/%d/maps", pid);
unsigned num = 0;
if (!_print_ascii_file(fname, st, &num)) {
st->print_cr("Can not get library information for pid = %d", pid);
} else {
st->print_cr("Total number of mappings: %u", num);
}
}
struct loaded_modules_info_param {
os::LoadedModulesCallbackFunc callback;
void *param;
};
static int dl_iterate_callback(struct dl_phdr_info *info, size_t size, void *data) {
if ((info->dlpi_name == nullptr) || (*info->dlpi_name == '\0')) {
return 0;
}
struct loaded_modules_info_param *callback_param = reinterpret_cast<struct loaded_modules_info_param *>(data);
address base = nullptr;
address top = nullptr;
for (int idx = 0; idx < info->dlpi_phnum; idx++) {
const ElfW(Phdr) *phdr = info->dlpi_phdr + idx;
if (phdr->p_type == PT_LOAD) {
address raw_phdr_base = reinterpret_cast<address>(info->dlpi_addr + phdr->p_vaddr);
address phdr_base = align_down(raw_phdr_base, phdr->p_align);
if ((base == nullptr) || (base > phdr_base)) {
base = phdr_base;
}
address phdr_top = align_up(raw_phdr_base + phdr->p_memsz, phdr->p_align);
if ((top == nullptr) || (top < phdr_top)) {
top = phdr_top;
}
}
}
return callback_param->callback(info->dlpi_name, base, top, callback_param->param);
}
int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) {
struct loaded_modules_info_param callback_param = {callback, param};
return dl_iterate_phdr(&dl_iterate_callback, &callback_param);
}
void os::print_os_info_brief(outputStream* st) {
os::Linux::print_distro_info(st);
os::Posix::print_uname_info(st);
os::Linux::print_libversion_info(st);
}
void os::print_os_info(outputStream* st) {
st->print_cr("OS:");
os::Linux::print_distro_info(st);
os::Posix::print_uname_info(st);
os::Linux::print_uptime_info(st);
// Print warning if unsafe chroot environment detected
if (unsafe_chroot_detected) {
st->print_cr("WARNING!! %s", unstable_chroot_error);
}
os::Linux::print_libversion_info(st);
os::Posix::print_rlimit_info(st);
os::Posix::print_load_average(st);
st->cr();
os::Linux::print_system_memory_info(st);
st->cr();
os::Linux::print_process_memory_info(st);
st->cr();
os::Linux::print_proc_sys_info(st);
st->cr();
if (os::Linux::print_ld_preload_file(st)) {
st->cr();
}
if (os::Linux::print_container_info(st)) {
st->cr();
}
VM_Version::print_platform_virtualization_info(st);
os::Linux::print_steal_info(st);
}
// Try to identify popular distros.
// Most Linux distributions have a /etc/XXX-release file, which contains
// the OS version string. Newer Linux distributions have a /etc/lsb-release
// file that also contains the OS version string. Some have more than one
// /etc/XXX-release file (e.g. Mandrake has both /etc/mandrake-release and
// /etc/redhat-release.), so the order is important.
// Any Linux that is based on Redhat (i.e. Oracle, Mandrake, Sun JDS...) have
// their own specific XXX-release file as well as a redhat-release file.
// Because of this the XXX-release file needs to be searched for before the
// redhat-release file.
// Since Red Hat and SuSE have an lsb-release file that is not very descriptive the
// search for redhat-release / SuSE-release needs to be before lsb-release.
// Since the lsb-release file is the new standard it needs to be searched
// before the older style release files.
// Searching system-release (Red Hat) and os-release (other Linuxes) are a
// next to last resort. The os-release file is a new standard that contains
// distribution information and the system-release file seems to be an old
// standard that has been replaced by the lsb-release and os-release files.
// Searching for the debian_version file is the last resort. It contains
// an informative string like "6.0.6" or "wheezy/sid". Because of this
// "Debian " is printed before the contents of the debian_version file.
const char* distro_files[] = {
"/etc/oracle-release",
"/etc/mandriva-release",
"/etc/mandrake-release",
"/etc/sun-release",
"/etc/redhat-release",
"/etc/lsb-release",
"/etc/turbolinux-release",
"/etc/gentoo-release",
"/etc/ltib-release",
"/etc/angstrom-version",
"/etc/system-release",
"/etc/os-release",
"/etc/SuSE-release", // Deprecated in favor of os-release since SuSE 12
nullptr };
void os::Linux::print_distro_info(outputStream* st) {
for (int i = 0;; i++) {
const char* file = distro_files[i];
if (file == nullptr) {
break; // done
}
// If file prints, we found it.
if (_print_ascii_file(file, st)) {
return;
}
}
if (file_exists("/etc/debian_version")) {
st->print("Debian ");
_print_ascii_file("/etc/debian_version", st);
} else {
st->print_cr("Linux");
}
}
static void parse_os_info_helper(FILE* fp, char* distro, size_t length, bool get_first_line) {
char buf[256];
while (fgets(buf, sizeof(buf), fp)) {
// Edit out extra stuff in expected format
if (strstr(buf, "DISTRIB_DESCRIPTION=") != nullptr || strstr(buf, "PRETTY_NAME=") != nullptr) {
char* ptr = strstr(buf, "\""); // the name is in quotes
if (ptr != nullptr) {
ptr++; // go beyond first quote
char* nl = strchr(ptr, '\"');
if (nl != nullptr) *nl = '\0';
strncpy(distro, ptr, length);
} else {
ptr = strstr(buf, "=");
ptr++; // go beyond equals then
char* nl = strchr(ptr, '\n');
if (nl != nullptr) *nl = '\0';
strncpy(distro, ptr, length);
}
return;
} else if (get_first_line) {
char* nl = strchr(buf, '\n');
if (nl != nullptr) *nl = '\0';
strncpy(distro, buf, length);
return;
}
}
// print last line and close
char* nl = strchr(buf, '\n');
if (nl != nullptr) *nl = '\0';
strncpy(distro, buf, length);
}
static void parse_os_info(char* distro, size_t length, const char* file) {
FILE* fp = os::fopen(file, "r");
if (fp != nullptr) {
// if suse format, print out first line
bool get_first_line = (strcmp(file, "/etc/SuSE-release") == 0);
parse_os_info_helper(fp, distro, length, get_first_line);
fclose(fp);
}
}
void os::get_summary_os_info(char* buf, size_t buflen) {
for (int i = 0;; i++) {
const char* file = distro_files[i];
if (file == nullptr) {
break; // ran out of distro_files
}
if (file_exists(file)) {
parse_os_info(buf, buflen, file);
return;
}
}
// special case for debian
if (file_exists("/etc/debian_version")) {
strncpy(buf, "Debian ", buflen);
if (buflen > 7) {
parse_os_info(&buf[7], buflen-7, "/etc/debian_version");
}
} else {
strncpy(buf, "Linux", buflen);
}
}
void os::Linux::print_libversion_info(outputStream* st) {
// libc, pthread
st->print("libc: ");
st->print("%s ", os::Linux::libc_version());
st->print("%s ", os::Linux::libpthread_version());
st->cr();
}
void os::Linux::print_proc_sys_info(outputStream* st) {
_print_ascii_file_h("/proc/sys/kernel/threads-max (system-wide limit on the number of threads)",
"/proc/sys/kernel/threads-max", st);
_print_ascii_file_h("/proc/sys/vm/max_map_count (maximum number of memory map areas a process may have)",
"/proc/sys/vm/max_map_count", st);
_print_ascii_file_h("/proc/sys/vm/swappiness (control to define how aggressively the kernel swaps out anonymous memory)",
"/proc/sys/vm/swappiness", st);
_print_ascii_file_h("/proc/sys/kernel/pid_max (system-wide limit on number of process identifiers)",
"/proc/sys/kernel/pid_max", st);
}
void os::Linux::print_system_memory_info(outputStream* st) {
_print_ascii_file_h("/proc/meminfo", "/proc/meminfo", st, false);
st->cr();
// some information regarding THPs; for details see
// https://www.kernel.org/doc/Documentation/vm/transhuge.txt
_print_ascii_file_h("/sys/kernel/mm/transparent_hugepage/enabled",
"/sys/kernel/mm/transparent_hugepage/enabled", st);
_print_ascii_file_h("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size",
"/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", st);
_print_ascii_file_h("/sys/kernel/mm/transparent_hugepage/shmem_enabled",
"/sys/kernel/mm/transparent_hugepage/shmem_enabled", st);
_print_ascii_file_h("/sys/kernel/mm/transparent_hugepage/defrag (defrag/compaction efforts parameter)",
"/sys/kernel/mm/transparent_hugepage/defrag", st);
}
bool os::Linux::query_process_memory_info(os::Linux::meminfo_t* info) {
FILE* f = os::fopen("/proc/self/status", "r");
const int num_values = sizeof(os::Linux::meminfo_t) / sizeof(size_t);
int num_found = 0;
char buf[256];
info->vmsize = info->vmpeak = info->vmrss = info->vmhwm = info->vmswap =
info->rssanon = info->rssfile = info->rssshmem = -1;
if (f != nullptr) {
while (::fgets(buf, sizeof(buf), f) != nullptr && num_found < num_values) {
if ( (info->vmsize == -1 && sscanf(buf, "VmSize: %zd kB", &info->vmsize) == 1) ||
(info->vmpeak == -1 && sscanf(buf, "VmPeak: %zd kB", &info->vmpeak) == 1) ||
(info->vmswap == -1 && sscanf(buf, "VmSwap: %zd kB", &info->vmswap) == 1) ||
(info->vmhwm == -1 && sscanf(buf, "VmHWM: %zd kB", &info->vmhwm) == 1) ||
(info->vmrss == -1 && sscanf(buf, "VmRSS: %zd kB", &info->vmrss) == 1) ||
(info->rssanon == -1 && sscanf(buf, "RssAnon: %zd kB", &info->rssanon) == 1) || // Needs Linux 4.5
(info->rssfile == -1 && sscanf(buf, "RssFile: %zd kB", &info->rssfile) == 1) || // Needs Linux 4.5
(info->rssshmem == -1 && sscanf(buf, "RssShmem: %zd kB", &info->rssshmem) == 1) // Needs Linux 4.5
)
{
num_found ++;
}
}
fclose(f);
return true;
}
return false;
}
// Accurate memory information need Linux 4.14 or newer
bool os::Linux::query_accurate_process_memory_info(os::Linux::accurate_meminfo_t* info) {
FILE* f = os::fopen("/proc/self/smaps_rollup", "r");
if (f == nullptr) {
return false;
}
const size_t num_values = sizeof(os::Linux::accurate_meminfo_t) / sizeof(size_t);
size_t num_found = 0;
char buf[256];
info->rss = info->pss = info->pssdirty = info->pssanon =
info->pssfile = info->pssshmem = info->swap = info->swappss = -1;
while (::fgets(buf, sizeof(buf), f) != nullptr && num_found < num_values) {
if ( (info->rss == -1 && sscanf(buf, "Rss: %zd kB", &info->rss) == 1) ||
(info->pss == -1 && sscanf(buf, "Pss: %zd kB", &info->pss) == 1) ||
(info->pssdirty == -1 && sscanf(buf, "Pss_Dirty: %zd kB", &info->pssdirty) == 1) ||
(info->pssanon == -1 && sscanf(buf, "Pss_Anon: %zd kB", &info->pssanon) == 1) ||
(info->pssfile == -1 && sscanf(buf, "Pss_File: %zd kB", &info->pssfile) == 1) ||
(info->pssshmem == -1 && sscanf(buf, "Pss_Shmem: %zd kB", &info->pssshmem) == 1) ||
(info->swap == -1 && sscanf(buf, "Swap: %zd kB", &info->swap) == 1) ||
(info->swappss == -1 && sscanf(buf, "SwapPss: %zd kB", &info->swappss) == 1)
)
{
num_found ++;
}
}
fclose(f);
return true;
}
#ifdef __GLIBC__
// For Glibc, print a one-liner with the malloc tunables.
// Most important and popular is MALLOC_ARENA_MAX, but we are
// thorough and print them all.
static void print_glibc_malloc_tunables(outputStream* st) {
static const char* var[] = {
// the new variant
"GLIBC_TUNABLES",
// legacy variants
"MALLOC_CHECK_", "MALLOC_TOP_PAD_", "MALLOC_PERTURB_",
"MALLOC_MMAP_THRESHOLD_", "MALLOC_TRIM_THRESHOLD_",
"MALLOC_MMAP_MAX_", "MALLOC_ARENA_TEST", "MALLOC_ARENA_MAX",
nullptr};
st->print("glibc malloc tunables: ");
bool printed = false;
for (int i = 0; var[i] != nullptr; i ++) {
const char* const val = ::getenv(var[i]);
if (val != nullptr) {
st->print("%s%s=%s", (printed ? ", " : ""), var[i], val);
printed = true;
}
}
if (!printed) {
st->print("(default)");
}
}
#endif // __GLIBC__
void os::Linux::print_process_memory_info(outputStream* st) {
st->print_cr("Process Memory:");
// Print virtual and resident set size; peak values; swap; and for
// rss its components if the kernel is recent enough.
meminfo_t info;
if (query_process_memory_info(&info)) {
st->print_cr("Virtual Size: %zdK (peak: %zdK)", info.vmsize, info.vmpeak);
st->print("Resident Set Size: %zdK (peak: %zdK)", info.vmrss, info.vmhwm);
if (info.rssanon != -1) { // requires kernel >= 4.5
st->print(" (anon: %zdK, file: %zdK, shmem: %zdK)",
info.rssanon, info.rssfile, info.rssshmem);
}
st->cr();
if (info.vmswap != -1) { // requires kernel >= 2.6.34
st->print_cr("Swapped out: %zdK", info.vmswap);
}
} else {
st->print_cr("Could not open /proc/self/status to get process memory related information");
}
// glibc only:
// - Print outstanding allocations using mallinfo
// - Print glibc tunables
#ifdef __GLIBC__
size_t total_allocated = 0;
size_t free_retained = 0;
bool might_have_wrapped = false;
glibc_mallinfo mi;
os::Linux::get_mallinfo(&mi, &might_have_wrapped);
total_allocated = mi.uordblks + mi.hblkhd;
free_retained = mi.fordblks;
#ifdef _LP64
// If legacy mallinfo(), we can still print the values if we are sure they cannot have wrapped.
might_have_wrapped = might_have_wrapped && (info.vmsize * K) > UINT_MAX;
#endif
st->print_cr("C-Heap outstanding allocations: %zuK, retained: %zuK%s",
total_allocated / K, free_retained / K,
might_have_wrapped ? " (may have wrapped)" : "");
// Tunables
print_glibc_malloc_tunables(st);
st->cr();
#endif
}
bool os::Linux::print_ld_preload_file(outputStream* st) {
return _print_ascii_file("/etc/ld.so.preload", st, nullptr, "/etc/ld.so.preload:");
}
void os::Linux::print_uptime_info(outputStream* st) {
struct sysinfo sinfo;
int ret = sysinfo(&sinfo);
if (ret == 0) {
os::print_dhm(st, "OS uptime:", (long) sinfo.uptime);
}
}
bool os::Linux::print_container_info(outputStream* st) {
if (!OSContainer::is_containerized()) {
st->print_cr("container information not found.");
return false;
}
st->print_cr("container (cgroup) information:");
const char *p_ct = OSContainer::container_type();
st->print_cr("container_type: %s", p_ct != nullptr ? p_ct : "not supported");
char *p = OSContainer::cpu_cpuset_cpus();
st->print_cr("cpu_cpuset_cpus: %s", p != nullptr ? p : "not supported");
free(p);
p = OSContainer::cpu_cpuset_memory_nodes();
st->print_cr("cpu_memory_nodes: %s", p != nullptr ? p : "not supported");
free(p);
int i = OSContainer::active_processor_count();
st->print("active_processor_count: ");
if (i > 0) {
if (ActiveProcessorCount > 0) {
st->print_cr("%d, but overridden by -XX:ActiveProcessorCount %d", i, ActiveProcessorCount);
} else {
st->print_cr("%d", i);
}
} else {
st->print_cr("not supported");
}
i = OSContainer::cpu_quota();
st->print("cpu_quota: ");
if (i > 0) {
st->print_cr("%d", i);
} else {
st->print_cr("%s", i == OSCONTAINER_ERROR ? "not supported" : "no quota");
}
i = OSContainer::cpu_period();
st->print("cpu_period: ");
if (i > 0) {
st->print_cr("%d", i);
} else {
st->print_cr("%s", i == OSCONTAINER_ERROR ? "not supported" : "no period");
}
i = OSContainer::cpu_shares();
st->print("cpu_shares: ");
if (i > 0) {
st->print_cr("%d", i);
} else {
st->print_cr("%s", i == OSCONTAINER_ERROR ? "not supported" : "no shares");
}
OSContainer::print_container_helper(st, OSContainer::memory_limit_in_bytes(), "memory_limit_in_bytes");
OSContainer::print_container_helper(st, OSContainer::memory_and_swap_limit_in_bytes(), "memory_and_swap_limit_in_bytes");
OSContainer::print_container_helper(st, OSContainer::memory_soft_limit_in_bytes(), "memory_soft_limit_in_bytes");
OSContainer::print_container_helper(st, OSContainer::memory_usage_in_bytes(), "memory_usage_in_bytes");
OSContainer::print_container_helper(st, OSContainer::memory_max_usage_in_bytes(), "memory_max_usage_in_bytes");
OSContainer::print_container_helper(st, OSContainer::rss_usage_in_bytes(), "rss_usage_in_bytes");
OSContainer::print_container_helper(st, OSContainer::cache_usage_in_bytes(), "cache_usage_in_bytes");
OSContainer::print_version_specific_info(st);
jlong j = OSContainer::pids_max();
st->print("maximum number of tasks: ");
if (j > 0) {
st->print_cr(JLONG_FORMAT, j);
} else {
st->print_cr("%s", j == OSCONTAINER_ERROR ? "not supported" : "unlimited");
}
j = OSContainer::pids_current();
st->print("current number of tasks: ");
if (j > 0) {
st->print_cr(JLONG_FORMAT, j);
} else {
if (j == OSCONTAINER_ERROR) {
st->print_cr("not supported");
}
}
return true;
}
void os::Linux::print_steal_info(outputStream* st) {
if (has_initial_tick_info) {
CPUPerfTicks pticks;
bool res = os::Linux::get_tick_information(&pticks, -1);
if (res && pticks.has_steal_ticks) {
uint64_t steal_ticks_difference = pticks.steal - initial_steal_ticks;
uint64_t total_ticks_difference = pticks.total - initial_total_ticks;
double steal_ticks_perc = 0.0;
if (total_ticks_difference != 0) {
steal_ticks_perc = (double) steal_ticks_difference / (double)total_ticks_difference;
}
st->print_cr("Steal ticks since vm start: " UINT64_FORMAT, steal_ticks_difference);
st->print_cr("Steal ticks percentage since vm start:%7.3f", steal_ticks_perc);
}
}
}
void os::print_memory_info(outputStream* st) {
st->print("Memory:");
st->print(" %zuk page", os::vm_page_size()>>10);
// values in struct sysinfo are "unsigned long"
struct sysinfo si;
sysinfo(&si);
st->print(", physical " UINT64_FORMAT "k",
os::physical_memory() >> 10);
st->print("(" UINT64_FORMAT "k free)",
os::available_memory() >> 10);
st->print(", swap " UINT64_FORMAT "k",
((jlong)si.totalswap * si.mem_unit) >> 10);
st->print("(" UINT64_FORMAT "k free)",
((jlong)si.freeswap * si.mem_unit) >> 10);
st->cr();
st->print("Page Sizes: ");
_page_sizes.print_on(st);
st->cr();
}
// Print the first "model name" line and the first "flags" line
// that we find and nothing more. We assume "model name" comes
// before "flags" so if we find a second "model name", then the
// "flags" field is considered missing.
static bool print_model_name_and_flags(outputStream* st, char* buf, size_t buflen) {
#if defined(IA32) || defined(AMD64)
// Other platforms have less repetitive cpuinfo files
FILE *fp = os::fopen("/proc/cpuinfo", "r");
if (fp) {
bool model_name_printed = false;
while (!feof(fp)) {
if (fgets(buf, (int)buflen, fp)) {
// Assume model name comes before flags
if (strstr(buf, "model name") != nullptr) {
if (!model_name_printed) {
st->print_raw("CPU Model and flags from /proc/cpuinfo:\n");
st->print_raw(buf);
model_name_printed = true;
} else {
// model name printed but not flags? Odd, just return
fclose(fp);
return true;
}
}
// print the flags line too
if (strstr(buf, "flags") != nullptr) {
st->print_raw(buf);
fclose(fp);
return true;
}
}
}
fclose(fp);
}
#endif // x86 platforms
return false;
}
// additional information about CPU e.g. available frequency ranges
static void print_sys_devices_cpu_info(outputStream* st) {
_print_ascii_file_h("Online cpus", "/sys/devices/system/cpu/online", st);
_print_ascii_file_h("Offline cpus", "/sys/devices/system/cpu/offline", st);
if (ExtensiveErrorReports) {
// cache related info (cpu 0, should be similar for other CPUs)
for (unsigned int i=0; i < 10; i++) { // handle max. 10 cache entries
char hbuf_level[60];
char hbuf_type[60];
char hbuf_size[60];
char hbuf_coherency_line_size[80];
snprintf(hbuf_level, 60, "/sys/devices/system/cpu/cpu0/cache/index%u/level", i);
snprintf(hbuf_type, 60, "/sys/devices/system/cpu/cpu0/cache/index%u/type", i);
snprintf(hbuf_size, 60, "/sys/devices/system/cpu/cpu0/cache/index%u/size", i);
snprintf(hbuf_coherency_line_size, 80, "/sys/devices/system/cpu/cpu0/cache/index%u/coherency_line_size", i);
if (os::file_exists(hbuf_level)) {
_print_ascii_file_h("cache level", hbuf_level, st);
_print_ascii_file_h("cache type", hbuf_type, st);
_print_ascii_file_h("cache size", hbuf_size, st);
_print_ascii_file_h("cache coherency line size", hbuf_coherency_line_size, st);
}
}
}
// we miss the cpufreq entries on Power and s390x
#if defined(IA32) || defined(AMD64)
_print_ascii_file_h("BIOS frequency limitation", "/sys/devices/system/cpu/cpu0/cpufreq/bios_limit", st);
_print_ascii_file_h("Frequency switch latency (ns)", "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_transition_latency", st);
_print_ascii_file_h("Available cpu frequencies", "/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies", st);
// min and max should be in the Available range but still print them (not all info might be available for all kernels)
if (ExtensiveErrorReports) {
_print_ascii_file_h("Maximum cpu frequency", "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq", st);
_print_ascii_file_h("Minimum cpu frequency", "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq", st);
_print_ascii_file_h("Current cpu frequency", "/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq", st);
}
// governors are power schemes, see https://wiki.archlinux.org/index.php/CPU_frequency_scaling
if (ExtensiveErrorReports) {
_print_ascii_file_h("Available governors", "/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors", st);
}
_print_ascii_file_h("Current governor", "/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor", st);
// Core performance boost, see https://www.kernel.org/doc/Documentation/cpu-freq/boost.txt
// Raise operating frequency of some cores in a multi-core package if certain conditions apply, e.g.
// whole chip is not fully utilized
_print_ascii_file_h("Core performance/turbo boost", "/sys/devices/system/cpu/cpufreq/boost", st);
#endif
}
void os::pd_print_cpu_info(outputStream* st, char* buf, size_t buflen) {
// Only print the model name if the platform provides this as a summary
if (!print_model_name_and_flags(st, buf, buflen)) {
_print_ascii_file_h("/proc/cpuinfo", "/proc/cpuinfo", st, false);
}
st->cr();
print_sys_devices_cpu_info(st);
}
#if INCLUDE_JFR
void os::jfr_report_memory_info() {
os::Linux::meminfo_t info;
if (os::Linux::query_process_memory_info(&info)) {
// Send the RSS JFR event
EventResidentSetSize event;
event.set_size(info.vmrss * K);
event.set_peak(info.vmhwm * K);
event.commit();
} else {
// Log a warning
static bool first_warning = true;
if (first_warning) {
log_warning(jfr)("Error fetching RSS values: query_process_memory_info failed");
first_warning = false;
}
}
}
#endif // INCLUDE_JFR
#if defined(AMD64) || defined(IA32) || defined(X32)
const char* search_string = "model name";
#elif defined(M68K)
const char* search_string = "CPU";
#elif defined(PPC64)
const char* search_string = "cpu";
#elif defined(S390)
const char* search_string = "machine =";
#elif defined(SPARC)
const char* search_string = "cpu";
#else
const char* search_string = "Processor";
#endif
// Parses the cpuinfo file for string representing the model name.
void os::get_summary_cpu_info(char* cpuinfo, size_t length) {
FILE* fp = os::fopen("/proc/cpuinfo", "r");
if (fp != nullptr) {
while (!feof(fp)) {
char buf[256];
if (fgets(buf, sizeof(buf), fp)) {
char* start = strstr(buf, search_string);
if (start != nullptr) {
char *ptr = start + strlen(search_string);
char *end = buf + strlen(buf);
while (ptr != end) {
// skip whitespace and colon for the rest of the name.
if (*ptr != ' ' && *ptr != '\t' && *ptr != ':') {
break;
}
ptr++;
}
if (ptr != end) {
// reasonable string, get rid of newline and keep the rest
char* nl = strchr(buf, '\n');
if (nl != nullptr) *nl = '\0';
strncpy(cpuinfo, ptr, length);
fclose(fp);
return;
}
}
}
}
fclose(fp);
}
// cpuinfo not found or parsing failed, just print generic string. The entire
// /proc/cpuinfo file will be printed later in the file (or enough of it for x86)
#if defined(AARCH64)
strncpy(cpuinfo, "AArch64", length);
#elif defined(AMD64)
strncpy(cpuinfo, "x86_64", length);
#elif defined(ARM) // Order wrt. AARCH64 is relevant!
strncpy(cpuinfo, "ARM", length);
#elif defined(IA32)
strncpy(cpuinfo, "x86_32", length);
#elif defined(PPC)
strncpy(cpuinfo, "PPC64", length);
#elif defined(RISCV)
strncpy(cpuinfo, LP64_ONLY("RISCV64") NOT_LP64("RISCV32"), length);
#elif defined(S390)
strncpy(cpuinfo, "S390", length);
#elif defined(SPARC)
strncpy(cpuinfo, "sparcv9", length);
#elif defined(ZERO_LIBARCH)
strncpy(cpuinfo, ZERO_LIBARCH, length);
#else
strncpy(cpuinfo, "unknown", length);
#endif
}
static char saved_jvm_path[MAXPATHLEN] = {0};
// Find the full path to the current module, libjvm.so
void os::jvm_path(char *buf, jint buflen) {
// Error checking.
if (buflen < MAXPATHLEN) {
assert(false, "must use a large-enough buffer");
buf[0] = '\0';
return;
}
// Lazy resolve the path to current module.
if (saved_jvm_path[0] != 0) {
strcpy(buf, saved_jvm_path);
return;
}
char dli_fname[MAXPATHLEN];
dli_fname[0] = '\0';
bool ret = dll_address_to_library_name(
CAST_FROM_FN_PTR(address, os::jvm_path),
dli_fname, sizeof(dli_fname), nullptr);
assert(ret, "cannot locate libjvm");
char *rp = nullptr;
if (ret && dli_fname[0] != '\0') {
rp = os::realpath(dli_fname, buf, buflen);
}
if (rp == nullptr) {
return;
}
// If executing unit tests we require JAVA_HOME to point to the real JDK.
if (Arguments::executing_unit_tests()) {
// Look for JAVA_HOME in the environment.
char* java_home_var = ::getenv("JAVA_HOME");
if (java_home_var != nullptr && java_home_var[0] != 0) {
// Check the current module name "libjvm.so".
const char* p = strrchr(buf, '/');
if (p == nullptr) {
return;
}
assert(strstr(p, "/libjvm") == p, "invalid library name");
stringStream ss(buf, buflen);
rp = os::realpath(java_home_var, buf, buflen);
if (rp == nullptr) {
return;
}
assert((int)strlen(buf) < buflen, "Ran out of buffer room");
ss.print("%s/lib", buf);
if (0 == access(buf, F_OK)) {
// Use current module name "libjvm.so"
ss.print("/%s/libjvm%s", Abstract_VM_Version::vm_variant(), JNI_LIB_SUFFIX);
assert(strcmp(buf + strlen(buf) - strlen(JNI_LIB_SUFFIX), JNI_LIB_SUFFIX) == 0,
"buf has been truncated");
} else {
// Go back to path of .so
rp = os::realpath(dli_fname, buf, buflen);
if (rp == nullptr) {
return;
}
}
}
}
strncpy(saved_jvm_path, buf, MAXPATHLEN);
saved_jvm_path[MAXPATHLEN - 1] = '\0';
}
////////////////////////////////////////////////////////////////////////////////
// Virtual Memory
// Rationale behind this function:
// current (Mon Apr 25 20:12:18 MSD 2005) oprofile drops samples without executable
// mapping for address (see lookup_dcookie() in the kernel module), thus we cannot get
// samples for JITted code. Here we create private executable mapping over the code cache
// and then we can use standard (well, almost, as mapping can change) way to provide
// info for the reporting script by storing timestamp and location of symbol
void linux_wrap_code(char* base, size_t size) {
static volatile jint cnt = 0;
static_assert(sizeof(off_t) == 8, "Expected Large File Support in this file");
if (!UseOprofile) {
return;
}
char buf[PATH_MAX+1];
int num = Atomic::add(&cnt, 1);
snprintf(buf, sizeof(buf), "%s/hs-vm-%d-%d",
os::get_temp_directory(), os::current_process_id(), num);
unlink(buf);
int fd = ::open(buf, O_CREAT | O_RDWR, S_IRWXU);
if (fd != -1) {
off_t rv = ::lseek(fd, size-2, SEEK_SET);
if (rv != (off_t)-1) {
if (::write(fd, "", 1) == 1) {
mmap(base, size,
PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE, fd, 0);
}
}
::close(fd);
unlink(buf);
}
}
static bool recoverable_mmap_error(int err) {
// See if the error is one we can let the caller handle. This
// list of errno values comes from JBS-6843484. I can't find a
// Linux man page that documents this specific set of errno
// values so while this list currently matches Solaris, it may
// change as we gain experience with this failure mode.
switch (err) {
case EBADF:
case EINVAL:
case ENOTSUP:
// let the caller deal with these errors
return true;
default:
// Any remaining errors on this OS can cause our reserved mapping
// to be lost. That can cause confusion where different data
// structures think they have the same memory mapped. The worst
// scenario is if both the VM and a library think they have the
// same memory mapped.
return false;
}
}
static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
int err) {
warning("INFO: os::commit_memory(" PTR_FORMAT ", %zu, %d) failed; error='%s' (errno=%d)",
p2i(addr), size, exec, os::strerror(err), err);
}
static void warn_fail_commit_memory(char* addr, size_t size,
size_t alignment_hint, bool exec,
int err) {
warning("INFO: os::commit_memory(" PTR_FORMAT ", %zu, %zu, %d) failed; error='%s' (errno=%d)",
p2i(addr), size, alignment_hint, exec, os::strerror(err), err);
}
// NOTE: Linux kernel does not really reserve the pages for us.
// All it does is to check if there are enough free pages
// left at the time of mmap(). This could be a potential
// problem.
int os::Linux::commit_memory_impl(char* addr, size_t size, bool exec) {
int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
uintptr_t res = (uintptr_t) ::mmap(addr, size, prot,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
if (res != (uintptr_t) MAP_FAILED) {
if (UseNUMAInterleaving) {
numa_make_global(addr, size);
}
return 0;
} else {
ErrnoPreserver ep;
log_trace(os, map)("mmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(addr, size),
os::strerror(ep.saved_errno()));
}
int err = errno; // save errno from mmap() call above
if (!recoverable_mmap_error(err)) {
ErrnoPreserver ep;
log_trace(os, map)("mmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(addr, size),
os::strerror(ep.saved_errno()));
warn_fail_commit_memory(addr, size, exec, err);
vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "committing reserved memory.");
}
return err;
}
bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
return os::Linux::commit_memory_impl(addr, size, exec) == 0;
}
void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
const char* mesg) {
assert(mesg != nullptr, "mesg must be specified");
int err = os::Linux::commit_memory_impl(addr, size, exec);
if (err != 0) {
// the caller wants all commit errors to exit with the specified mesg:
warn_fail_commit_memory(addr, size, exec, err);
vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "%s", mesg);
}
}
// Define MAP_HUGETLB here so we can build HotSpot on old systems.
#ifndef MAP_HUGETLB
#define MAP_HUGETLB 0x40000
#endif
// If mmap flags are set with MAP_HUGETLB and the system supports multiple
// huge page sizes, flag bits [26:31] can be used to encode the log2 of the
// desired huge page size. Otherwise, the system's default huge page size will be used.
// See mmap(2) man page for more info (since Linux 3.8).
// https://lwn.net/Articles/533499/
#ifndef MAP_HUGE_SHIFT
#define MAP_HUGE_SHIFT 26
#endif
// Define MADV_HUGEPAGE here so we can build HotSpot on old systems.
#ifndef MADV_HUGEPAGE
#define MADV_HUGEPAGE 14
#endif
// Define MADV_POPULATE_WRITE here so we can build HotSpot on old systems.
#define MADV_POPULATE_WRITE_value 23
#ifndef MADV_POPULATE_WRITE
#define MADV_POPULATE_WRITE MADV_POPULATE_WRITE_value
#else
// Sanity-check our assumed default value if we build with a new enough libc.
STATIC_ASSERT(MADV_POPULATE_WRITE == MADV_POPULATE_WRITE_value);
#endif
// Note that the value for MAP_FIXED_NOREPLACE differs between architectures, but all architectures
// supported by OpenJDK share the same flag value.
#define MAP_FIXED_NOREPLACE_value 0x100000
#ifndef MAP_FIXED_NOREPLACE
#define MAP_FIXED_NOREPLACE MAP_FIXED_NOREPLACE_value
#else
// Sanity-check our assumed default value if we build with a new enough libc.
STATIC_ASSERT(MAP_FIXED_NOREPLACE == MAP_FIXED_NOREPLACE_value);
#endif
int os::Linux::commit_memory_impl(char* addr, size_t size,
size_t alignment_hint, bool exec) {
int err = os::Linux::commit_memory_impl(addr, size, exec);
if (err == 0) {
realign_memory(addr, size, alignment_hint);
}
return err;
}
bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
bool exec) {
return os::Linux::commit_memory_impl(addr, size, alignment_hint, exec) == 0;
}
void os::pd_commit_memory_or_exit(char* addr, size_t size,
size_t alignment_hint, bool exec,
const char* mesg) {
assert(mesg != nullptr, "mesg must be specified");
int err = os::Linux::commit_memory_impl(addr, size, alignment_hint, exec);
if (err != 0) {
// the caller wants all commit errors to exit with the specified mesg:
warn_fail_commit_memory(addr, size, alignment_hint, exec, err);
vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "%s", mesg);
}
}
void os::Linux::madvise_transparent_huge_pages(void* addr, size_t bytes) {
// We don't check the return value: madvise(MADV_HUGEPAGE) may not
// be supported or the memory may already be backed by huge pages.
::madvise(addr, bytes, MADV_HUGEPAGE);
}
void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
if (Linux::should_madvise_anonymous_thps() && alignment_hint > vm_page_size()) {
Linux::madvise_transparent_huge_pages(addr, bytes);
}
}
// Hints to the OS that the memory is no longer needed and may be reclaimed by the OS when convenient.
// The memory will be re-acquired on touch without needing explicit recommitting.
void os::pd_disclaim_memory(char *addr, size_t bytes) {
::madvise(addr, bytes, MADV_DONTNEED);
}
size_t os::pd_pretouch_memory(void* first, void* last, size_t page_size) {
const size_t len = pointer_delta(last, first, sizeof(char)) + page_size;
// Use madvise to pretouch on Linux when THP is used, and fallback to the
// common method if unsupported. THP can form right after madvise rather than
// being assembled later.
if (HugePages::thp_mode() == THPMode::always || UseTransparentHugePages) {
int err = 0;
if (UseMadvPopulateWrite &&
::madvise(first, len, MADV_POPULATE_WRITE) == -1) {
err = errno;
}
if (!UseMadvPopulateWrite || err == EINVAL) { // Not to use or not supported
// When using THP we need to always pre-touch using small pages as the
// OS will initially always use small pages.
return os::vm_page_size();
} else if (err != 0) {
log_info(gc, os)("::madvise(" PTR_FORMAT ", %zu, %d) failed; "
"error='%s' (errno=%d)", p2i(first), len,
MADV_POPULATE_WRITE, os::strerror(err), err);
}
return 0;
}
return page_size;
}
void os::numa_make_global(char *addr, size_t bytes) {
Linux::numa_interleave_memory(addr, bytes);
}
// Define for numa_set_bind_policy(int). Setting the argument to 0 will set the
// bind policy to MPOL_PREFERRED for the current thread.
#define USE_MPOL_PREFERRED 0
void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
// To make NUMA and large pages more robust when both enabled, we need to ease
// the requirements on where the memory should be allocated. MPOL_BIND is the
// default policy and it will force memory to be allocated on the specified
// node. Changing this to MPOL_PREFERRED will prefer to allocate the memory on
// the specified node, but will not force it. Using this policy will prevent
// getting SIGBUS when trying to allocate large pages on NUMA nodes with no
// free large pages.
Linux::numa_set_bind_policy(USE_MPOL_PREFERRED);
Linux::numa_tonode_memory(addr, bytes, lgrp_hint);
}
bool os::numa_topology_changed() { return false; }
size_t os::numa_get_groups_num() {
// Return just the number of nodes in which it's possible to allocate memory
// (in numa terminology, configured nodes).
return Linux::numa_num_configured_nodes();
}
int os::numa_get_group_id() {
int cpu_id = Linux::sched_getcpu();
if (cpu_id != -1) {
int lgrp_id = Linux::get_node_by_cpu(cpu_id);
if (lgrp_id != -1) {
return lgrp_id;
}
}
return 0;
}
int os::numa_get_group_id_for_address(const void* address) {
void** pages = const_cast<void**>(&address);
int id = -1;
if (os::Linux::numa_move_pages(0, 1, pages, nullptr, &id, 0) == -1) {
return -1;
}
if (id < 0) {
return -1;
}
return id;
}
bool os::numa_get_group_ids_for_range(const void** addresses, int* lgrp_ids, size_t count) {
void** pages = const_cast<void**>(addresses);
return os::Linux::numa_move_pages(0, count, pages, nullptr, lgrp_ids, 0) == 0;
}
int os::Linux::get_existing_num_nodes() {
int node;
int highest_node_number = Linux::numa_max_node();
int num_nodes = 0;
// Get the total number of nodes in the system including nodes without memory.
for (node = 0; node <= highest_node_number; node++) {
if (is_node_in_existing_nodes(node)) {
num_nodes++;
}
}
return num_nodes;
}
size_t os::numa_get_leaf_groups(uint *ids, size_t size) {
int highest_node_number = Linux::numa_max_node();
size_t i = 0;
// Map all node ids in which it is possible to allocate memory. Also nodes are
// not always consecutively available, i.e. available from 0 to the highest
// node number. If the nodes have been bound explicitly using numactl membind,
// then allocate memory from those nodes only.
for (int node = 0; node <= highest_node_number; node++) {
if (Linux::is_node_in_bound_nodes(node)) {
ids[i++] = checked_cast<uint>(node);
}
}
return i;
}
int os::Linux::sched_getcpu_syscall(void) {
unsigned int cpu = 0;
long retval = -1;
#if defined(IA32)
#ifndef SYS_getcpu
#define SYS_getcpu 318
#endif
retval = syscall(SYS_getcpu, &cpu, nullptr, nullptr);
#elif defined(AMD64)
// Unfortunately we have to bring all these macros here from vsyscall.h
// to be able to compile on old linuxes.
#define __NR_vgetcpu 2
#define VSYSCALL_START (-10UL << 20)
#define VSYSCALL_SIZE 1024
#define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
typedef long (*vgetcpu_t)(unsigned int *cpu, unsigned int *node, unsigned long *tcache);
vgetcpu_t vgetcpu = (vgetcpu_t)VSYSCALL_ADDR(__NR_vgetcpu);
retval = vgetcpu(&cpu, nullptr, nullptr);
#endif
return (retval == -1) ? -1 : cpu;
}
void os::Linux::sched_getcpu_init() {
// sched_getcpu() should be in libc.
set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
dlsym(RTLD_DEFAULT, "sched_getcpu")));
// If it's not, try a direct syscall.
if (sched_getcpu() == -1) {
set_sched_getcpu(CAST_TO_FN_PTR(sched_getcpu_func_t,
(void*)&sched_getcpu_syscall));
}
if (sched_getcpu() == -1) {
vm_exit_during_initialization("getcpu(2) system call not supported by kernel");
}
}
// Something to do with the numa-aware allocator needs these symbols
extern "C" JNIEXPORT void numa_warn(int number, char *where, ...) { }
extern "C" JNIEXPORT void numa_error(char *where) { }
// Handle request to load libnuma symbol version 1.1 (API v1). If it fails
// load symbol from base version instead.
void* os::Linux::libnuma_dlsym(void* handle, const char *name) {
void *f = dlvsym(handle, name, "libnuma_1.1");
if (f == nullptr) {
f = dlsym(handle, name);
}
return f;
}
// Handle request to load libnuma symbol version 1.2 (API v2) only.
// Return null if the symbol is not defined in this particular version.
void* os::Linux::libnuma_v2_dlsym(void* handle, const char* name) {
return dlvsym(handle, name, "libnuma_1.2");
}
// Check numa dependent syscalls
static bool numa_syscall_check() {
// NUMA APIs depend on several syscalls. E.g., get_mempolicy is required for numa_get_membind and
// numa_get_interleave_mask. But these dependent syscalls can be unsupported for various reasons.
// Especially in dockers, get_mempolicy is not allowed with the default configuration. So it's necessary
// to check whether the syscalls are available. Currently, only get_mempolicy is checked since checking
// others like mbind would cause unexpected side effects.
#ifdef SYS_get_mempolicy
int dummy = 0;
if (syscall(SYS_get_mempolicy, &dummy, nullptr, 0, (void*)&dummy, 3) == -1) {
return false;
}
#endif
return true;
}
bool os::Linux::libnuma_init() {
// Requires sched_getcpu() and numa dependent syscalls support
if ((sched_getcpu() != -1) && numa_syscall_check()) {
void *handle = dlopen("libnuma.so.1", RTLD_LAZY);
if (handle != nullptr) {
set_numa_node_to_cpus(CAST_TO_FN_PTR(numa_node_to_cpus_func_t,
libnuma_dlsym(handle, "numa_node_to_cpus")));
set_numa_node_to_cpus_v2(CAST_TO_FN_PTR(numa_node_to_cpus_v2_func_t,
libnuma_v2_dlsym(handle, "numa_node_to_cpus")));
set_numa_max_node(CAST_TO_FN_PTR(numa_max_node_func_t,
libnuma_dlsym(handle, "numa_max_node")));
set_numa_num_configured_nodes(CAST_TO_FN_PTR(numa_num_configured_nodes_func_t,
libnuma_dlsym(handle, "numa_num_configured_nodes")));
set_numa_available(CAST_TO_FN_PTR(numa_available_func_t,
libnuma_dlsym(handle, "numa_available")));
set_numa_tonode_memory(CAST_TO_FN_PTR(numa_tonode_memory_func_t,
libnuma_dlsym(handle, "numa_tonode_memory")));
set_numa_interleave_memory(CAST_TO_FN_PTR(numa_interleave_memory_func_t,
libnuma_dlsym(handle, "numa_interleave_memory")));
set_numa_interleave_memory_v2(CAST_TO_FN_PTR(numa_interleave_memory_v2_func_t,
libnuma_v2_dlsym(handle, "numa_interleave_memory")));
set_numa_set_bind_policy(CAST_TO_FN_PTR(numa_set_bind_policy_func_t,
libnuma_dlsym(handle, "numa_set_bind_policy")));
set_numa_bitmask_isbitset(CAST_TO_FN_PTR(numa_bitmask_isbitset_func_t,
libnuma_dlsym(handle, "numa_bitmask_isbitset")));
set_numa_bitmask_equal(CAST_TO_FN_PTR(numa_bitmask_equal_func_t,
libnuma_dlsym(handle, "numa_bitmask_equal")));
set_numa_distance(CAST_TO_FN_PTR(numa_distance_func_t,
libnuma_dlsym(handle, "numa_distance")));
set_numa_get_membind(CAST_TO_FN_PTR(numa_get_membind_func_t,
libnuma_v2_dlsym(handle, "numa_get_membind")));
set_numa_get_interleave_mask(CAST_TO_FN_PTR(numa_get_interleave_mask_func_t,
libnuma_v2_dlsym(handle, "numa_get_interleave_mask")));
set_numa_move_pages(CAST_TO_FN_PTR(numa_move_pages_func_t,
libnuma_dlsym(handle, "numa_move_pages")));
set_numa_set_preferred(CAST_TO_FN_PTR(numa_set_preferred_func_t,
libnuma_dlsym(handle, "numa_set_preferred")));
set_numa_get_run_node_mask(CAST_TO_FN_PTR(numa_get_run_node_mask_func_t,
libnuma_v2_dlsym(handle, "numa_get_run_node_mask")));
if (numa_available() != -1) {
set_numa_all_nodes((unsigned long*)libnuma_dlsym(handle, "numa_all_nodes"));
set_numa_all_nodes_ptr((struct bitmask **)libnuma_dlsym(handle, "numa_all_nodes_ptr"));
set_numa_nodes_ptr((struct bitmask **)libnuma_dlsym(handle, "numa_nodes_ptr"));
set_numa_interleave_bitmask(_numa_get_interleave_mask());
set_numa_membind_bitmask(_numa_get_membind());
set_numa_cpunodebind_bitmask(_numa_get_run_node_mask());
// Create an index -> node mapping, since nodes are not always consecutive
_nindex_to_node = new (mtInternal) GrowableArray<int>(0, mtInternal);
rebuild_nindex_to_node_map();
// Create a cpu -> node mapping
_cpu_to_node = new (mtInternal) GrowableArray<int>(0, mtInternal);
rebuild_cpu_to_node_map();
return true;
}
}
}
return false;
}
size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
if (THPStackMitigation) {
// If THPs are unconditionally enabled, the following scenario can lead to huge RSS
// - parent thread spawns, in quick succession, multiple child threads
// - child threads are slow to start
// - thread stacks of future child threads are adjacent and get merged into one large VMA
// by the kernel, and subsequently transformed into huge pages by khugepaged
// - child threads come up, place JVM guard pages, thus splinter the large VMA, splinter
// the huge pages into many (still paged-in) small pages.
// The result of that sequence are thread stacks that are fully paged-in even though the
// threads did not even start yet.
// We prevent that by letting the glibc allocate a guard page, which causes a VMA with different
// permission bits to separate two ajacent thread stacks and therefore prevent merging stacks
// into one VMA.
//
// Yes, this means we have two guard sections - the glibc and the JVM one - per thread. But the
// cost for that one extra protected page is dwarfed from a large win in performance and memory
// that avoiding interference by khugepaged buys us.
return os::vm_page_size();
}
// Creating guard page is very expensive. Java thread has HotSpot
// guard pages, only enable glibc guard page for non-Java threads.
// (Remember: compiler thread is a Java thread, too!)
return ((thr_type == java_thread || thr_type == compiler_thread) ? 0 : os::vm_page_size());
}
void os::Linux::rebuild_nindex_to_node_map() {
int highest_node_number = Linux::numa_max_node();
nindex_to_node()->clear();
for (int node = 0; node <= highest_node_number; node++) {
if (Linux::is_node_in_existing_nodes(node)) {
nindex_to_node()->append(node);
}
}
}
// rebuild_cpu_to_node_map() constructs a table mapping cpud id to node id.
// The table is later used in get_node_by_cpu().
void os::Linux::rebuild_cpu_to_node_map() {
const int NCPUS = 32768; // Since the buffer size computation is very obscure
// in libnuma (possible values are starting from 16,
// and continuing up with every other power of 2, but less
// than the maximum number of CPUs supported by kernel), and
// is a subject to change (in libnuma version 2 the requirements
// are more reasonable) we'll just hardcode the number they use
// in the library.
constexpr int BitsPerCLong = (int)sizeof(long) * CHAR_BIT;
int cpu_num = processor_count();
int cpu_map_size = NCPUS / BitsPerCLong;
int cpu_map_valid_size =
MIN2((cpu_num + BitsPerCLong - 1) / BitsPerCLong, cpu_map_size);
cpu_to_node()->clear();
cpu_to_node()->at_grow(cpu_num - 1);
int node_num = get_existing_num_nodes();
int distance = 0;
int closest_distance = INT_MAX;
int closest_node = 0;
unsigned long *cpu_map = NEW_C_HEAP_ARRAY(unsigned long, cpu_map_size, mtInternal);
for (int i = 0; i < node_num; i++) {
// Check if node is configured (not a memory-less node). If it is not, find
// the closest configured node. Check also if node is bound, i.e. it's allowed
// to allocate memory from the node. If it's not allowed, map cpus in that node
// to the closest node from which memory allocation is allowed.
if (!is_node_in_configured_nodes(nindex_to_node()->at(i)) ||
!is_node_in_bound_nodes(nindex_to_node()->at(i))) {
closest_distance = INT_MAX;
// Check distance from all remaining nodes in the system. Ignore distance
// from itself, from another non-configured node, and from another non-bound
// node.
for (int m = 0; m < node_num; m++) {
if (m != i &&
is_node_in_configured_nodes(nindex_to_node()->at(m)) &&
is_node_in_bound_nodes(nindex_to_node()->at(m))) {
distance = numa_distance(nindex_to_node()->at(i), nindex_to_node()->at(m));
// If a closest node is found, update. There is always at least one
// configured and bound node in the system so there is always at least
// one node close.
if (distance != 0 && distance < closest_distance) {
closest_distance = distance;
closest_node = nindex_to_node()->at(m);
}
}
}
} else {
// Current node is already a configured node.
closest_node = nindex_to_node()->at(i);
}
// Get cpus from the original node and map them to the closest node. If node
// is a configured node (not a memory-less node), then original node and
// closest node are the same.
if (numa_node_to_cpus(nindex_to_node()->at(i), cpu_map, cpu_map_size * (int)sizeof(unsigned long)) != -1) {
for (int j = 0; j < cpu_map_valid_size; j++) {
if (cpu_map[j] != 0) {
for (int k = 0; k < BitsPerCLong; k++) {
if (cpu_map[j] & (1UL << k)) {
int cpu_index = j * BitsPerCLong + k;
#ifndef PRODUCT
if (UseDebuggerErgo1 && cpu_index >= (int)cpu_num) {
// Some debuggers limit the processor count without
// intercepting the NUMA APIs. Just fake the values.
cpu_index = 0;
}
#endif
cpu_to_node()->at_put(cpu_index, closest_node);
}
}
}
}
}
}
FREE_C_HEAP_ARRAY(unsigned long, cpu_map);
}
int os::Linux::numa_node_to_cpus(int node, unsigned long *buffer, int bufferlen) {
// use the latest version of numa_node_to_cpus if available
if (_numa_node_to_cpus_v2 != nullptr) {
// libnuma bitmask struct
struct bitmask {
unsigned long size; /* number of bits in the map */
unsigned long *maskp;
};
struct bitmask mask;
mask.maskp = (unsigned long *)buffer;
mask.size = bufferlen * 8;
return _numa_node_to_cpus_v2(node, &mask);
} else if (_numa_node_to_cpus != nullptr) {
return _numa_node_to_cpus(node, buffer, bufferlen);
}
return -1;
}
int os::Linux::get_node_by_cpu(int cpu_id) {
if (cpu_to_node() != nullptr && cpu_id >= 0 && cpu_id < cpu_to_node()->length()) {
return cpu_to_node()->at(cpu_id);
}
return -1;
}
GrowableArray<int>* os::Linux::_cpu_to_node;
GrowableArray<int>* os::Linux::_nindex_to_node;
os::Linux::sched_getcpu_func_t os::Linux::_sched_getcpu;
os::Linux::numa_node_to_cpus_func_t os::Linux::_numa_node_to_cpus;
os::Linux::numa_node_to_cpus_v2_func_t os::Linux::_numa_node_to_cpus_v2;
os::Linux::numa_max_node_func_t os::Linux::_numa_max_node;
os::Linux::numa_num_configured_nodes_func_t os::Linux::_numa_num_configured_nodes;
os::Linux::numa_available_func_t os::Linux::_numa_available;
os::Linux::numa_tonode_memory_func_t os::Linux::_numa_tonode_memory;
os::Linux::numa_interleave_memory_func_t os::Linux::_numa_interleave_memory;
os::Linux::numa_interleave_memory_v2_func_t os::Linux::_numa_interleave_memory_v2;
os::Linux::numa_set_bind_policy_func_t os::Linux::_numa_set_bind_policy;
os::Linux::numa_bitmask_isbitset_func_t os::Linux::_numa_bitmask_isbitset;
os::Linux::numa_bitmask_equal_func_t os::Linux::_numa_bitmask_equal;
os::Linux::numa_distance_func_t os::Linux::_numa_distance;
os::Linux::numa_get_membind_func_t os::Linux::_numa_get_membind;
os::Linux::numa_get_interleave_mask_func_t os::Linux::_numa_get_interleave_mask;
os::Linux::numa_get_run_node_mask_func_t os::Linux::_numa_get_run_node_mask;
os::Linux::numa_move_pages_func_t os::Linux::_numa_move_pages;
os::Linux::numa_set_preferred_func_t os::Linux::_numa_set_preferred;
os::Linux::NumaAllocationPolicy os::Linux::_current_numa_policy;
unsigned long* os::Linux::_numa_all_nodes;
struct bitmask* os::Linux::_numa_all_nodes_ptr;
struct bitmask* os::Linux::_numa_nodes_ptr;
struct bitmask* os::Linux::_numa_interleave_bitmask;
struct bitmask* os::Linux::_numa_membind_bitmask;
struct bitmask* os::Linux::_numa_cpunodebind_bitmask;
bool os::pd_uncommit_memory(char* addr, size_t size, bool exec) {
uintptr_t res = (uintptr_t) ::mmap(addr, size, PROT_NONE,
MAP_PRIVATE|MAP_FIXED|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
if (res == (uintptr_t) MAP_FAILED) {
ErrnoPreserver ep;
log_trace(os, map)("mmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(addr, size),
os::strerror(ep.saved_errno()));
return false;
}
return true;
}
static address get_stack_commited_bottom(address bottom, size_t size) {
address nbot = bottom;
address ntop = bottom + size;
size_t page_sz = os::vm_page_size();
unsigned pages = checked_cast<unsigned>(size / page_sz);
unsigned char vec[1];
unsigned imin = 1, imax = pages + 1, imid;
int mincore_return_value = 0;
assert(imin <= imax, "Unexpected page size");
while (imin < imax) {
imid = (imax + imin) / 2;
nbot = ntop - (imid * page_sz);
// Use a trick with mincore to check whether the page is mapped or not.
// mincore sets vec to 1 if page resides in memory and to 0 if page
// is swapped output but if page we are asking for is unmapped
// it returns -1,ENOMEM
mincore_return_value = mincore(nbot, page_sz, vec);
if (mincore_return_value == -1) {
// Page is not mapped go up
// to find first mapped page
if (errno != EAGAIN) {
assert(errno == ENOMEM, "Unexpected mincore errno");
imax = imid;
}
} else {
// Page is mapped go down
// to find first not mapped page
imin = imid + 1;
}
}
nbot = nbot + page_sz;
// Adjust stack bottom one page up if last checked page is not mapped
if (mincore_return_value == -1) {
nbot = nbot + page_sz;
}
return nbot;
}
// Linux uses a growable mapping for the stack, and if the mapping for
// the stack guard pages is not removed when we detach a thread the
// stack cannot grow beyond the pages where the stack guard was
// mapped. If at some point later in the process the stack expands to
// that point, the Linux kernel cannot expand the stack any further
// because the guard pages are in the way, and a segfault occurs.
//
// However, it's essential not to split the stack region by unmapping
// a region (leaving a hole) that's already part of the stack mapping,
// so if the stack mapping has already grown beyond the guard pages at
// the time we create them, we have to truncate the stack mapping.
// So, we need to know the extent of the stack mapping when
// create_stack_guard_pages() is called.
// We only need this for stacks that are growable: at the time of
// writing thread stacks don't use growable mappings (i.e. those
// creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
// only applies to the main thread.
// If the (growable) stack mapping already extends beyond the point
// where we're going to put our guard pages, truncate the mapping at
// that point by munmap()ping it. This ensures that when we later
// munmap() the guard pages we don't leave a hole in the stack
// mapping. This only affects the main/primordial thread
bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
if (os::is_primordial_thread()) {
// As we manually grow stack up to bottom inside create_attached_thread(),
// it's likely that os::Linux::initial_thread_stack_bottom is mapped and
// we don't need to do anything special.
// Check it first, before calling heavy function.
uintptr_t stack_extent = (uintptr_t) os::Linux::initial_thread_stack_bottom();
unsigned char vec[1];
if (mincore((address)stack_extent, os::vm_page_size(), vec) == -1) {
// Fallback to slow path on all errors, including EAGAIN
assert((uintptr_t)addr >= stack_extent,
"Sanity: addr should be larger than extent, " PTR_FORMAT " >= " PTR_FORMAT,
p2i(addr), stack_extent);
stack_extent = (uintptr_t) get_stack_commited_bottom(
os::Linux::initial_thread_stack_bottom(),
(size_t)addr - stack_extent);
}
if (stack_extent < (uintptr_t)addr) {
::munmap((void*)stack_extent, (uintptr_t)(addr - stack_extent));
}
}
return os::commit_memory(addr, size, !ExecMem);
}
// If this is a growable mapping, remove the guard pages entirely by
// munmap()ping them. If not, just call uncommit_memory(). This only
// affects the main/primordial thread, but guard against future OS changes.
// It's safe to always unmap guard pages for primordial thread because we
// always place it right after end of the mapped region.
bool os::remove_stack_guard_pages(char* addr, size_t size) {
uintptr_t stack_extent, stack_base;
if (os::is_primordial_thread()) {
return ::munmap(addr, size) == 0;
}
return os::uncommit_memory(addr, size);
}
// 'requested_addr' is only treated as a hint, the return value may or
// may not start from the requested address. Unlike Linux mmap(), this
// function returns null to indicate failure.
static char* anon_mmap(char* requested_addr, size_t bytes) {
// If a requested address was given:
//
// The POSIX-conforming way is to *omit* MAP_FIXED. This will leave existing mappings intact.
// If the requested mapping area is blocked by a pre-existing mapping, the kernel will map
// somewhere else. On Linux, that alternative address appears to have no relation to the
// requested address.
// Unfortunately, this is not what we need - if we requested a specific address, we'd want
// to map there and nowhere else. Therefore we will unmap the block again, which means we
// just executed a needless mmap->munmap cycle.
// Since Linux 4.17, the kernel offers MAP_FIXED_NOREPLACE. With this flag, if a pre-
// existing mapping exists, the kernel will not map at an alternative point but instead
// return an error. We can therefore save that unnecessary mmap-munmap cycle.
//
// Backward compatibility: Older kernels will ignore the unknown flag; so mmap will behave
// as in mode (a).
const int flags = MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS |
((requested_addr != nullptr) ? MAP_FIXED_NOREPLACE : 0);
// Map reserved/uncommitted pages PROT_NONE so we fail early if we
// touch an uncommitted page. Otherwise, the read/write might
// succeed if we have enough swap space to back the physical page.
char* addr = (char*)::mmap(requested_addr, bytes, PROT_NONE, flags, -1, 0);
if (addr == MAP_FAILED) {
ErrnoPreserver ep;
log_trace(os, map)("mmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(requested_addr, bytes),
os::strerror(ep.saved_errno()));
return nullptr;
}
return addr;
}
// Allocate (using mmap, NO_RESERVE, with small pages) at either a given request address
// (req_addr != nullptr) or with a given alignment.
// - bytes shall be a multiple of alignment.
// - req_addr can be null. If not null, it must be a multiple of alignment.
// - alignment sets the alignment at which memory shall be allocated.
// It must be a multiple of allocation granularity.
// Returns address of memory or null. If req_addr was not null, will only return
// req_addr or null.
static char* anon_mmap_aligned(char* req_addr, size_t bytes, size_t alignment) {
size_t extra_size = bytes;
if (req_addr == nullptr && alignment > 0) {
extra_size += alignment;
}
char* start = anon_mmap(req_addr, extra_size);
if (start != nullptr) {
if (req_addr != nullptr) {
if (start != req_addr) {
if (::munmap(start, extra_size) != 0) {
ErrnoPreserver ep;
log_trace(os, map)("munmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(start, extra_size),
os::strerror(ep.saved_errno()));
}
start = nullptr;
}
} else {
char* const start_aligned = align_up(start, alignment);
char* const end_aligned = start_aligned + bytes;
char* const end = start + extra_size;
if (start_aligned > start) {
const size_t l = start_aligned - start;
if (::munmap(start, l) != 0) {
ErrnoPreserver ep;
log_trace(os, map)("munmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(start, l),
os::strerror(ep.saved_errno()));
}
}
if (end_aligned < end) {
const size_t l = end - end_aligned;
if (::munmap(end_aligned, l) != 0) {
ErrnoPreserver ep;
log_trace(os, map)("munmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(end_aligned, l),
os::strerror(ep.saved_errno()));
}
}
start = start_aligned;
}
}
return start;
}
static int anon_munmap(char * addr, size_t size) {
if (::munmap(addr, size) != 0) {
ErrnoPreserver ep;
log_trace(os, map)("munmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(addr, size),
os::strerror(ep.saved_errno()));
return 0;
}
return 1;
}
char* os::pd_reserve_memory(size_t bytes, bool exec) {
return anon_mmap(nullptr, bytes);
}
bool os::pd_release_memory(char* addr, size_t size) {
return anon_munmap(addr, size);
}
#ifdef CAN_SHOW_REGISTERS_ON_ASSERT
extern char* g_assert_poison; // assertion poison page address
#endif
static bool linux_mprotect(char* addr, size_t size, int prot) {
// Linux wants the mprotect address argument to be page aligned.
char* bottom = (char*)align_down((intptr_t)addr, os::vm_page_size());
// According to SUSv3, mprotect() should only be used with mappings
// established by mmap(), and mmap() always maps whole pages. Unaligned
// 'addr' likely indicates problem in the VM (e.g. trying to change
// protection of malloc'ed or statically allocated memory). Check the
// caller if you hit this assert.
assert(addr == bottom, "sanity check");
size = align_up(pointer_delta(addr, bottom, 1) + size, os::vm_page_size());
// Don't log anything if we're executing in the poison page signal handling
// context. It can lead to reentrant use of other parts of the VM code.
#ifdef CAN_SHOW_REGISTERS_ON_ASSERT
if (addr != g_assert_poison)
#endif
Events::log_memprotect(nullptr, "Protecting memory [" INTPTR_FORMAT "," INTPTR_FORMAT "] with protection modes %x", p2i(bottom), p2i(bottom+size), prot);
return ::mprotect(bottom, size, prot) == 0;
}
// Set protections specified
bool os::protect_memory(char* addr, size_t bytes, ProtType prot,
bool is_committed) {
unsigned int p = 0;
switch (prot) {
case MEM_PROT_NONE: p = PROT_NONE; break;
case MEM_PROT_READ: p = PROT_READ; break;
case MEM_PROT_RW: p = PROT_READ|PROT_WRITE; break;
case MEM_PROT_RWX: p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
default:
ShouldNotReachHere();
}
// is_committed is unused.
return linux_mprotect(addr, bytes, p);
}
bool os::guard_memory(char* addr, size_t size) {
return linux_mprotect(addr, size, PROT_NONE);
}
bool os::unguard_memory(char* addr, size_t size) {
return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
}
static int hugetlbfs_page_size_flag(size_t page_size) {
if (page_size != HugePages::default_explicit_hugepage_size()) {
return (exact_log2(page_size) << MAP_HUGE_SHIFT);
}
return 0;
}
static bool hugetlbfs_sanity_check(size_t page_size) {
const os::PageSizes page_sizes = HugePages::explicit_hugepage_info().pagesizes();
assert(page_sizes.contains(page_size), "Invalid page sizes passed");
// Include the page size flag to ensure we sanity check the correct page size.
int flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB | hugetlbfs_page_size_flag(page_size);
void *p = mmap(nullptr, page_size, PROT_READ|PROT_WRITE, flags, -1, 0);
if (p != MAP_FAILED) {
// Mapping succeeded, sanity check passed.
munmap(p, page_size);
return true;
} else {
log_info(pagesize)("Large page size (" EXACTFMT ") failed sanity check, "
"checking if smaller large page sizes are usable",
EXACTFMTARGS(page_size));
for (size_t page_size_ = page_sizes.next_smaller(page_size);
page_size_ > os::vm_page_size();
page_size_ = page_sizes.next_smaller(page_size_)) {
flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB | hugetlbfs_page_size_flag(page_size_);
p = mmap(nullptr, page_size_, PROT_READ|PROT_WRITE, flags, -1, 0);
if (p != MAP_FAILED) {
// Mapping succeeded, sanity check passed.
munmap(p, page_size_);
log_info(pagesize)("Large page size (" EXACTFMT ") passed sanity check",
EXACTFMTARGS(page_size_));
return true;
}
}
}
return false;
}
// From the coredump_filter documentation:
//
// - (bit 0) anonymous private memory
// - (bit 1) anonymous shared memory
// - (bit 2) file-backed private memory
// - (bit 3) file-backed shared memory
// - (bit 4) ELF header pages in file-backed private memory areas (it is
// effective only if the bit 2 is cleared)
// - (bit 5) hugetlb private memory
// - (bit 6) hugetlb shared memory
// - (bit 7) dax private memory
// - (bit 8) dax shared memory
//
static void set_coredump_filter(CoredumpFilterBit bit) {
FILE *f;
long cdm;
if ((f = os::fopen("/proc/self/coredump_filter", "r+")) == nullptr) {
return;
}
if (fscanf(f, "%lx", &cdm) != 1) {
fclose(f);
return;
}
long saved_cdm = cdm;
rewind(f);
cdm |= bit;
if (cdm != saved_cdm) {
fprintf(f, "%#lx", cdm);
}
fclose(f);
}
// Large page support
static size_t _large_page_size = 0;
static void warn_no_large_pages_configured() {
if (!FLAG_IS_DEFAULT(UseLargePages)) {
log_warning(pagesize)("UseLargePages disabled, no large pages configured and available on the system.");
}
}
struct LargePageInitializationLoggerMark {
~LargePageInitializationLoggerMark() {
LogTarget(Info, pagesize) lt;
if (lt.is_enabled()) {
LogStream ls(lt);
if (UseLargePages) {
ls.print_cr("UseLargePages=1, UseTransparentHugePages=%d", UseTransparentHugePages);
ls.print("Large page support enabled. Usable page sizes: ");
os::page_sizes().print_on(&ls);
ls.print_cr(". Default large page size: " EXACTFMT ".", EXACTFMTARGS(os::large_page_size()));
} else {
ls.print("Large page support %sdisabled.", uses_zgc_shmem_thp() ? "partially " : "");
}
}
}
static bool uses_zgc_shmem_thp() {
return UseZGC &&
// If user requested THP
((os::Linux::thp_requested() && HugePages::supports_shmem_thp()) ||
// If OS forced THP
HugePages::forced_shmem_thp());
}
};
static bool validate_thps_configured() {
assert(UseTransparentHugePages, "Sanity");
assert(os::Linux::thp_requested(), "Sanity");
if (UseZGC) {
if (!HugePages::supports_shmem_thp()) {
log_warning(pagesize)("Shared memory transparent huge pages are not enabled in the OS. "
"Set /sys/kernel/mm/transparent_hugepage/shmem_enabled to 'advise' to enable them.");
// UseTransparentHugePages has historically been tightly coupled with
// anonymous THPs. Fall through here and let the validity be determined
// by the OS configuration for anonymous THPs. ZGC doesn't use the flag
// but instead checks os::Linux::thp_requested().
}
}
if (!HugePages::supports_thp()) {
log_warning(pagesize)("Anonymous transparent huge pages are not enabled in the OS. "
"Set /sys/kernel/mm/transparent_hugepage/enabled to 'madvise' to enable them.");
log_warning(pagesize)("UseTransparentHugePages disabled, transparent huge pages are not supported by the operating system.");
return false;
}
return true;
}
void os::large_page_init() {
Linux::large_page_init();
}
void os::Linux::large_page_init() {
LargePageInitializationLoggerMark logger;
// Decide if the user asked for THPs before we update UseTransparentHugePages.
const bool large_pages_turned_off = !FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages;
_thp_requested = UseTransparentHugePages && !large_pages_turned_off;
// Query OS information first.
HugePages::initialize();
// If THPs are unconditionally enabled (THP mode "always"), khugepaged may attempt to
// coalesce small pages in thread stacks to huge pages. That costs a lot of memory and
// is usually unwanted for thread stacks. Therefore we attempt to prevent THP formation in
// thread stacks unless the user explicitly allowed THP formation by manually disabling
// -XX:-THPStackMitigation.
if (HugePages::thp_mode() == THPMode::always) {
if (THPStackMitigation) {
log_info(pagesize)("JVM will attempt to prevent THPs in thread stacks.");
} else {
log_info(pagesize)("JVM will *not* prevent THPs in thread stacks. This may cause high RSS.");
}
} else {
FLAG_SET_ERGO(THPStackMitigation, false); // Mitigation not needed
}
// Handle the case where we do not want to use huge pages
if (!UseLargePages &&
!UseTransparentHugePages) {
// Not using large pages.
return;
}
if (!FLAG_IS_DEFAULT(UseLargePages) && !UseLargePages) {
// The user explicitly turned off large pages.
UseTransparentHugePages = false;
return;
}
// Check if the OS supports THPs
if (UseTransparentHugePages && !validate_thps_configured()) {
UseLargePages = UseTransparentHugePages = false;
return;
}
// Check if the OS supports explicit hugepages.
if (!UseTransparentHugePages && !HugePages::supports_explicit_hugepages()) {
warn_no_large_pages_configured();
UseLargePages = false;
return;
}
if (UseTransparentHugePages) {
// In THP mode:
// - os::large_page_size() is the *THP page size*
// - os::pagesizes() has two members, the THP page size and the system page size
_large_page_size = HugePages::thp_pagesize();
if (_large_page_size == 0) {
log_info(pagesize) ("Cannot determine THP page size (kernel < 4.10 ?)");
_large_page_size = HugePages::thp_pagesize_fallback();
log_info(pagesize) ("Assuming THP page size to be: " EXACTFMT " (heuristics)", EXACTFMTARGS(_large_page_size));
}
_page_sizes.add(_large_page_size);
_page_sizes.add(os::vm_page_size());
// +UseTransparentHugePages implies +UseLargePages
UseLargePages = true;
} else {
// In explicit hugepage mode:
// - os::large_page_size() is the default explicit hugepage size (/proc/meminfo "Hugepagesize")
// - os::pagesizes() contains all hugepage sizes the kernel supports, regardless whether there
// are pages configured in the pool or not (from /sys/kernel/hugepages/hugepage-xxxx ...)
os::PageSizes all_large_pages = HugePages::explicit_hugepage_info().pagesizes();
const size_t default_large_page_size = HugePages::default_explicit_hugepage_size();
// 3) Consistency check and post-processing
size_t large_page_size = 0;
// Check LargePageSizeInBytes matches an available page size and if so set _large_page_size
// using LargePageSizeInBytes as the maximum allowed large page size. If LargePageSizeInBytes
// doesn't match an available page size set _large_page_size to default_large_page_size
// and use it as the maximum.
if (FLAG_IS_DEFAULT(LargePageSizeInBytes) ||
LargePageSizeInBytes == 0 ||
LargePageSizeInBytes == default_large_page_size) {
large_page_size = default_large_page_size;
log_info(pagesize)("Using the default large page size: " EXACTFMT,
EXACTFMTARGS(large_page_size));
} else {
if (all_large_pages.contains(LargePageSizeInBytes)) {
large_page_size = LargePageSizeInBytes;
log_info(pagesize)("Overriding default large page size (" EXACTFMT ") "
"using LargePageSizeInBytes: " EXACTFMT,
EXACTFMTARGS(default_large_page_size),
EXACTFMTARGS(large_page_size));
} else {
large_page_size = default_large_page_size;
log_info(pagesize)("LargePageSizeInBytes is not a valid large page size (" EXACTFMT ") "
"using the default large page size: " EXACTFMT,
EXACTFMTARGS(LargePageSizeInBytes),
EXACTFMTARGS(large_page_size));
}
}
// Do an additional sanity check to see if we can use the desired large page size
if (!hugetlbfs_sanity_check(large_page_size)) {
warn_no_large_pages_configured();
UseLargePages = false;
return;
}
_large_page_size = large_page_size;
// Populate _page_sizes with large page sizes less than or equal to
// _large_page_size.
for (size_t page_size = _large_page_size; page_size != 0;
page_size = all_large_pages.next_smaller(page_size)) {
_page_sizes.add(page_size);
}
}
set_coredump_filter(LARGEPAGES_BIT);
}
bool os::Linux::thp_requested() {
return _thp_requested;
}
bool os::Linux::should_madvise_anonymous_thps() {
return _thp_requested && HugePages::thp_mode() == THPMode::madvise;
}
bool os::Linux::should_madvise_shmem_thps() {
return _thp_requested && HugePages::shmem_thp_mode() == ShmemTHPMode::advise;
}
static void log_on_commit_special_failure(char* req_addr, size_t bytes,
size_t page_size, int error) {
assert(error == ENOMEM, "Only expect to fail if no memory is available");
log_info(pagesize)("Failed to reserve and commit memory with given page size. req_addr: " PTR_FORMAT
" size: " EXACTFMT ", page size: " EXACTFMT ", (errno = %d)",
p2i(req_addr), EXACTFMTARGS(bytes), EXACTFMTARGS(page_size), error);
}
static bool commit_memory_special(size_t bytes,
size_t page_size,
char* req_addr,
bool exec) {
assert(UseLargePages, "Should only get here for huge pages");
assert(!UseTransparentHugePages, "Should only get here for explicit hugepage mode");
assert(is_aligned(bytes, page_size), "Unaligned size");
assert(is_aligned(req_addr, page_size), "Unaligned address");
assert(req_addr != nullptr, "Must have a requested address for special mappings");
int prot = exec ? PROT_READ|PROT_WRITE|PROT_EXEC : PROT_READ|PROT_WRITE;
int flags = MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED;
// For large pages additional flags are required.
if (page_size > os::vm_page_size()) {
flags |= MAP_HUGETLB | hugetlbfs_page_size_flag(page_size);
}
char* addr = (char*)::mmap(req_addr, bytes, prot, flags, -1, 0);
if (addr == MAP_FAILED) {
log_on_commit_special_failure(req_addr, bytes, page_size, errno);
return false;
}
log_debug(pagesize)("Commit special mapping: " PTR_FORMAT ", size=" EXACTFMT ", page size=" EXACTFMT,
p2i(addr), EXACTFMTARGS(bytes), EXACTFMTARGS(page_size));
assert(is_aligned(addr, page_size), "Must be");
return true;
}
static char* reserve_memory_special_huge_tlbfs(size_t bytes,
size_t alignment,
size_t page_size,
char* req_addr,
bool exec) {
const os::PageSizes page_sizes = HugePages::explicit_hugepage_info().pagesizes();
assert(UseLargePages, "only for Huge TLBFS large pages");
assert(is_aligned(req_addr, alignment), "Must be");
assert(is_aligned(req_addr, page_size), "Must be");
assert(is_aligned(alignment, os::vm_allocation_granularity()), "Must be");
assert(page_sizes.contains(page_size), "Must be a valid page size");
assert(page_size > os::vm_page_size(), "Must be a large page size");
assert(bytes >= page_size, "Shouldn't allocate large pages for small sizes");
// We only end up here when at least 1 large page can be used.
// If the size is not a multiple of the large page size, we
// will mix the type of pages used, but in a descending order.
// Start off by reserving a range of the given size that is
// properly aligned. At this point no pages are committed. If
// a requested address is given it will be used and it must be
// aligned to both the large page size and the given alignment.
// The larger of the two will be used.
size_t required_alignment = MAX(page_size, alignment);
char* const aligned_start = anon_mmap_aligned(req_addr, bytes, required_alignment);
if (aligned_start == nullptr) {
return nullptr;
}
// First commit using large pages.
size_t large_bytes = align_down(bytes, page_size);
bool large_committed = commit_memory_special(large_bytes, page_size, aligned_start, exec);
if (large_committed && bytes == large_bytes) {
// The size was large page aligned so no additional work is
// needed even if the commit failed.
return aligned_start;
}
// The requested size requires some small pages as well.
char* small_start = aligned_start + large_bytes;
size_t small_size = bytes - large_bytes;
if (!large_committed) {
// Failed to commit large pages, so we need to unmap the
// reminder of the orinal reservation.
if (::munmap(small_start, small_size) != 0) {
ErrnoPreserver ep;
log_trace(os, map)("munmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(small_start, small_size),
os::strerror(ep.saved_errno()));
}
return nullptr;
}
// Commit the remaining bytes using small pages.
bool small_committed = commit_memory_special(small_size, os::vm_page_size(), small_start, exec);
if (!small_committed) {
// Failed to commit the remaining size, need to unmap
// the large pages part of the reservation.
if (::munmap(aligned_start, large_bytes) != 0) {
ErrnoPreserver ep;
log_trace(os, map)("munmap failed: " RANGEFMT " errno=(%s)",
RANGEFMTARGS(aligned_start, large_bytes),
os::strerror(ep.saved_errno()));
}
return nullptr;
}
return aligned_start;
}
char* os::pd_reserve_memory_special(size_t bytes, size_t alignment, size_t page_size,
char* req_addr, bool exec) {
assert(UseLargePages, "only for large pages");
char* const addr = reserve_memory_special_huge_tlbfs(bytes, alignment, page_size, req_addr, exec);
if (addr != nullptr) {
if (UseNUMAInterleaving) {
numa_make_global(addr, bytes);
}
}
return addr;
}
bool os::pd_release_memory_special(char* base, size_t bytes) {
assert(UseLargePages, "only for large pages");
// Plain munmap is sufficient
return pd_release_memory(base, bytes);
}
size_t os::large_page_size() {
return _large_page_size;
}
// explicit hugepages (hugetlbfs) allow application to commit large page memory
// on demand.
// However, when committing memory with hugepages fails, the region
// that was supposed to be committed will lose the old reservation
// and allow other threads to steal that memory region. Because of this
// behavior we can't commit hugetlbfs memory. Instead, we commit that
// memory at reservation.
bool os::can_commit_large_page_memory() {
return UseTransparentHugePages;
}
char* os::pd_attempt_map_memory_to_file_at(char* requested_addr, size_t bytes, int file_desc) {
assert(file_desc >= 0, "file_desc is not valid");
char* result = pd_attempt_reserve_memory_at(requested_addr, bytes, !ExecMem);
if (result != nullptr) {
if (replace_existing_mapping_with_file_mapping(result, bytes, file_desc) == nullptr) {
vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory"));
}
}
return result;
}
// Reserve memory at an arbitrary address, only if that area is
// available (and not reserved for something else).
char* os::pd_attempt_reserve_memory_at(char* requested_addr, size_t bytes, bool exec) {
// Assert only that the size is a multiple of the page size, since
// that's all that mmap requires, and since that's all we really know
// about at this low abstraction level. If we need higher alignment,
// we can either pass an alignment to this method or verify alignment
// in one of the methods further up the call chain. See bug 5044738.
assert(bytes % os::vm_page_size() == 0, "reserving unexpected size block");
// Linux mmap allows caller to pass an address as hint; give it a try first,
// if kernel honors the hint then we can return immediately.
char * addr = anon_mmap(requested_addr, bytes);
if (addr == requested_addr) {
return requested_addr;
}
if (addr != nullptr) {
// mmap() is successful but it fails to reserve at the requested address
log_trace(os, map)("Kernel rejected " PTR_FORMAT
", offered " PTR_FORMAT ".",
p2i(requested_addr),
p2i(addr));
anon_munmap(addr, bytes);
}
return nullptr;
}
size_t os::vm_min_address() {
// Determined by sysctl vm.mmap_min_addr. It exists as a safety zone to prevent
// null pointer dereferences.
// Most distros set this value to 64 KB. It *can* be zero, but rarely is. Here,
// we impose a minimum value if vm.mmap_min_addr is too low, for increased protection.
static size_t value = 0;
if (value == 0) {
assert(is_aligned(_vm_min_address_default, os::vm_allocation_granularity()), "Sanity");
FILE* f = os::fopen("/proc/sys/vm/mmap_min_addr", "r");
if (f != nullptr) {
if (fscanf(f, "%zu", &value) != 1) {
value = _vm_min_address_default;
}
fclose(f);
}
value = MAX2(_vm_min_address_default, value);
}
return value;
}
////////////////////////////////////////////////////////////////////////////////
// thread priority support
// Note: Normal Linux applications are run with SCHED_OTHER policy. SCHED_OTHER
// only supports dynamic priority, static priority must be zero. For real-time
// applications, Linux supports SCHED_RR which allows static priority (1-99).
// However, for large multi-threaded applications, SCHED_RR is not only slower
// than SCHED_OTHER, but also very unstable (my volano tests hang hard 4 out
// of 5 runs - Sep 2005).
//
// The following code actually changes the niceness of kernel-thread/LWP. It
// has an assumption that setpriority() only modifies one kernel-thread/LWP,
// not the entire user process, and user level threads are 1:1 mapped to kernel
// threads. It has always been the case, but could change in the future. For
// this reason, the code should not be used as default (ThreadPriorityPolicy=0).
// It is only used when ThreadPriorityPolicy=1 and may require system level permission
// (e.g., root privilege or CAP_SYS_NICE capability).
int os::java_to_os_priority[CriticalPriority + 1] = {
19, // 0 Entry should never be used
4, // 1 MinPriority
3, // 2
2, // 3
1, // 4
0, // 5 NormPriority
-1, // 6
-2, // 7
-3, // 8
-4, // 9 NearMaxPriority
-5, // 10 MaxPriority
-5 // 11 CriticalPriority
};
static int prio_init() {
if (ThreadPriorityPolicy == 1) {
if (geteuid() != 0) {
if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy) && !FLAG_IS_JIMAGE_RESOURCE(ThreadPriorityPolicy)) {
warning("-XX:ThreadPriorityPolicy=1 may require system level permission, " \
"e.g., being the root user. If the necessary permission is not " \
"possessed, changes to priority will be silently ignored.");
}
}
}
if (UseCriticalJavaThreadPriority) {
os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
}
return 0;
}
OSReturn os::set_native_priority(Thread* thread, int newpri) {
if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK;
int ret = setpriority(PRIO_PROCESS, thread->osthread()->thread_id(), newpri);
return (ret == 0) ? OS_OK : OS_ERR;
}
OSReturn os::get_native_priority(const Thread* const thread,
int *priority_ptr) {
if (!UseThreadPriorities || ThreadPriorityPolicy == 0) {
*priority_ptr = java_to_os_priority[NormPriority];
return OS_OK;
}
errno = 0;
*priority_ptr = getpriority(PRIO_PROCESS, thread->osthread()->thread_id());
return (*priority_ptr != -1 || errno == 0 ? OS_OK : OS_ERR);
}
// This is the fastest way to get thread cpu time on Linux.
// Returns cpu time (user+sys) for any thread, not only for current.
// POSIX compliant clocks are implemented in the kernels 2.6.16+.
// It might work on 2.6.10+ with a special kernel/glibc patch.
// For reference, please, see IEEE Std 1003.1-2004:
// http://www.unix.org/single_unix_specification
jlong os::Linux::fast_thread_cpu_time(clockid_t clockid) {
struct timespec tp;
int status = clock_gettime(clockid, &tp);
assert(status == 0, "clock_gettime error: %s", os::strerror(errno));
return (tp.tv_sec * NANOSECS_PER_SEC) + tp.tv_nsec;
}
// copy data between two file descriptor within the kernel
// the number of bytes written to out_fd is returned if transfer was successful
// otherwise, returns -1 that implies an error
jlong os::Linux::sendfile(int out_fd, int in_fd, jlong* offset, jlong count) {
return ::sendfile(out_fd, in_fd, (off_t*)offset, (size_t)count);
}
// Determine if the vmid is the parent pid for a child in a PID namespace.
// Return the namespace pid if so, otherwise -1.
int os::Linux::get_namespace_pid(int vmid) {
char fname[24];
int retpid = -1;
snprintf(fname, sizeof(fname), "/proc/%d/status", vmid);
FILE *fp = os::fopen(fname, "r");
if (fp) {
int pid, nspid;
int ret;
while (!feof(fp) && !ferror(fp)) {
ret = fscanf(fp, "NSpid: %d %d", &pid, &nspid);
if (ret == 1) {
break;
}
if (ret == 2) {
retpid = nspid;
break;
}
for (;;) {
int ch = fgetc(fp);
if (ch == EOF || ch == (int)'\n') break;
}
}
fclose(fp);
}
return retpid;
}
extern void report_error(char* file_name, int line_no, char* title,
char* format, ...);
// Some linux distributions (notably: Alpine Linux) include the
// grsecurity in the kernel. Of particular interest from a JVM perspective
// is PaX (https://pax.grsecurity.net/), which adds some security features
// related to page attributes. Specifically, the MPROTECT PaX functionality
// (https://pax.grsecurity.net/docs/mprotect.txt) prevents dynamic
// code generation by disallowing a (previously) writable page to be
// marked as executable. This is, of course, exactly what HotSpot does
// for both JIT compiled method, as well as for stubs, adapters, etc.
//
// Instead of crashing "lazily" when trying to make a page executable,
// this code probes for the presence of PaX and reports the failure
// eagerly.
static void check_pax(void) {
// Zero doesn't generate code dynamically, so no need to perform the PaX check
#ifndef ZERO
size_t size = os::vm_page_size();
void* p = ::mmap(nullptr, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED) {
log_debug(os)("os_linux.cpp: check_pax: mmap failed (%s)" , os::strerror(errno));
vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "failed to allocate memory for PaX check.");
}
int res = ::mprotect(p, size, PROT_READ|PROT_WRITE|PROT_EXEC);
if (res == -1) {
log_debug(os)("os_linux.cpp: check_pax: mprotect failed (%s)" , os::strerror(errno));
vm_exit_during_initialization(
"Failed to mark memory page as executable - check if grsecurity/PaX is enabled");
}
::munmap(p, size);
#endif
}
// this is called _before_ most of the global arguments have been parsed
void os::init(void) {
char dummy; // used to get a guess on initial stack address
int sys_pg_size = checked_cast<int>(sysconf(_SC_PAGESIZE));
if (sys_pg_size < 0) {
fatal("os_linux.cpp: os::init: sysconf failed (%s)",
os::strerror(errno));
}
size_t page_size = sys_pg_size;
OSInfo::set_vm_page_size(page_size);
OSInfo::set_vm_allocation_granularity(page_size);
if (os::vm_page_size() == 0) {
fatal("os_linux.cpp: os::init: OSInfo::set_vm_page_size failed");
}
_page_sizes.add(os::vm_page_size());
Linux::initialize_system_info();
#ifdef __GLIBC__
g_mallinfo = CAST_TO_FN_PTR(mallinfo_func_t, dlsym(RTLD_DEFAULT, "mallinfo"));
g_mallinfo2 = CAST_TO_FN_PTR(mallinfo2_func_t, dlsym(RTLD_DEFAULT, "mallinfo2"));
g_malloc_info = CAST_TO_FN_PTR(malloc_info_func_t, dlsym(RTLD_DEFAULT, "malloc_info"));
#endif // __GLIBC__
os::Linux::CPUPerfTicks pticks;
bool res = os::Linux::get_tick_information(&pticks, -1);
if (res && pticks.has_steal_ticks) {
has_initial_tick_info = true;
initial_total_ticks = pticks.total;
initial_steal_ticks = pticks.steal;
}
// _main_thread points to the thread that created/loaded the JVM.
Linux::_main_thread = pthread_self();
// retrieve entry point for pthread_setname_np
Linux::_pthread_setname_np =
(int(*)(pthread_t, const char*))dlsym(RTLD_DEFAULT, "pthread_setname_np");
check_pax();
// Check the availability of MADV_POPULATE_WRITE.
FLAG_SET_DEFAULT(UseMadvPopulateWrite, (::madvise(nullptr, 0, MADV_POPULATE_WRITE) == 0));
os::Posix::init();
}
// To install functions for atexit system call
extern "C" {
static void perfMemory_exit_helper() {
perfMemory_exit();
}
}
void os::pd_init_container_support() {
OSContainer::init();
}
void os::Linux::numa_init() {
// Java can be invoked as
// 1. Without numactl and heap will be allocated/configured on all nodes as
// per the system policy.
// 2. With numactl --interleave:
// Use numa_get_interleave_mask(v2) API to get nodes bitmask. The same
// API for membind case bitmask is reset.
// Interleave is only hint and Kernel can fallback to other nodes if
// no memory is available on the target nodes.
// 3. With numactl --membind:
// Use numa_get_membind(v2) API to get nodes bitmask. The same API for
// interleave case returns bitmask of all nodes.
// numa_all_nodes_ptr holds bitmask of all nodes.
// numa_get_interleave_mask(v2) and numa_get_membind(v2) APIs returns correct
// bitmask when externally configured to run on all or fewer nodes.
if (!Linux::libnuma_init()) {
disable_numa("Failed to initialize libnuma", true);
} else {
Linux::set_configured_numa_policy(Linux::identify_numa_policy());
if (Linux::numa_max_node() < 1) {
disable_numa("Only a single NUMA node is available", false);
} else if (Linux::is_bound_to_single_mem_node()) {
disable_numa("The process is bound to a single NUMA node", true);
} else if (Linux::mem_and_cpu_node_mismatch()) {
disable_numa("The process memory and cpu node configuration does not match", true);
} else {
LogTarget(Info,os) log;
LogStream ls(log);
struct bitmask* bmp = Linux::_numa_membind_bitmask;
const char* numa_mode = "membind";
if (Linux::is_running_in_interleave_mode()) {
bmp = Linux::_numa_interleave_bitmask;
numa_mode = "interleave";
}
ls.print("UseNUMA is enabled and invoked in '%s' mode."
" Heap will be configured using NUMA memory nodes:", numa_mode);
for (int node = 0; node <= Linux::numa_max_node(); node++) {
if (Linux::_numa_bitmask_isbitset(bmp, node)) {
ls.print(" %d", node);
}
}
}
}
// When NUMA requested, not-NUMA-aware allocations default to interleaving.
if (UseNUMA && !UseNUMAInterleaving) {
FLAG_SET_ERGO_IF_DEFAULT(UseNUMAInterleaving, true);
}
if (UseParallelGC && UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
// With static large pages we cannot uncommit a page, so there's no way
// we can make the adaptive lgrp chunk resizing work. If the user specified both
// UseNUMA and UseLargePages on the command line - warn and disable adaptive resizing.
if (UseAdaptiveSizePolicy || UseAdaptiveNUMAChunkSizing) {
warning("UseNUMA is not fully compatible with +UseLargePages, "
"disabling adaptive resizing (-XX:-UseAdaptiveSizePolicy -XX:-UseAdaptiveNUMAChunkSizing)");
UseAdaptiveSizePolicy = false;
UseAdaptiveNUMAChunkSizing = false;
}
}
}
void os::Linux::disable_numa(const char* reason, bool warning) {
if ((UseNUMA && FLAG_IS_CMDLINE(UseNUMA)) ||
(UseNUMAInterleaving && FLAG_IS_CMDLINE(UseNUMAInterleaving))) {
// Only issue a message if the user explicitly asked for NUMA support
if (warning) {
log_warning(os)("NUMA support disabled: %s", reason);
} else {
log_info(os)("NUMA support disabled: %s", reason);
}
}
FLAG_SET_ERGO(UseNUMA, false);
FLAG_SET_ERGO(UseNUMAInterleaving, false);
}
#if defined(IA32) && !defined(ZERO)
/*
* Work-around (execute code at a high address) for broken NX emulation using CS limit,
* Red Hat patch "Exec-Shield" (IA32 only).
*
* Map and execute at a high VA to prevent CS lazy updates race with SMP MM
* invalidation.Further code generation by the JVM will no longer cause CS limit
* updates.
*
* Affects IA32: RHEL 5 & 6, Ubuntu 10.04 (LTS), 10.10, 11.04, 11.10, 12.04.
* @see JDK-8023956
*/
static void workaround_expand_exec_shield_cs_limit() {
assert(os::Linux::initial_thread_stack_bottom() != nullptr, "sanity");
size_t page_size = os::vm_page_size();
/*
* JDK-8197429
*
* Expand the stack mapping to the end of the initial stack before
* attempting to install the codebuf. This is needed because newer
* Linux kernels impose a distance of a megabyte between stack
* memory and other memory regions. If we try to install the
* codebuf before expanding the stack the installation will appear
* to succeed but we'll get a segfault later if we expand the stack
* in Java code.
*
*/
if (os::is_primordial_thread()) {
address limit = os::Linux::initial_thread_stack_bottom();
if (! DisablePrimordialThreadGuardPages) {
limit += StackOverflow::stack_red_zone_size() +
StackOverflow::stack_yellow_zone_size();
}
os::Linux::expand_stack_to(limit);
}
/*
* Take the highest VA the OS will give us and exec
*
* Although using -(pagesz) as mmap hint works on newer kernel as you would
* think, older variants affected by this work-around don't (search forward only).
*
* On the affected distributions, we understand the memory layout to be:
*
* TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
*
* A few pages south main stack will do it.
*
* If we are embedded in an app other than launcher (initial != main stack),
* we don't have much control or understanding of the address space, just let it slide.
*/
char* hint = (char*)(os::Linux::initial_thread_stack_bottom() -
(StackOverflow::stack_guard_zone_size() + page_size));
char* codebuf = os::attempt_reserve_memory_at(hint, page_size, mtThread);
if (codebuf == nullptr) {
// JDK-8197429: There may be a stack gap of one megabyte between
// the limit of the stack and the nearest memory region: this is a
// Linux kernel workaround for CVE-2017-1000364. If we failed to
// map our codebuf, try again at an address one megabyte lower.
hint -= 1 * M;
codebuf = os::attempt_reserve_memory_at(hint, page_size, mtThread);
}
if ((codebuf == nullptr) || (!os::commit_memory(codebuf, page_size, true))) {
return; // No matter, we tried, best effort.
}
log_info(os)("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
// Some code to exec: the 'ret' instruction
codebuf[0] = 0xC3;
// Call the code in the codebuf
__asm__ volatile("call *%0" : : "r"(codebuf));
// keep the page mapped so CS limit isn't reduced.
}
#endif // defined(IA32) && !defined(ZERO)
// this is called _after_ the global arguments have been parsed
jint os::init_2(void) {
// This could be set after os::Posix::init() but all platforms
// have to set it the same so we have to mirror Solaris.
DEBUG_ONLY(os::set_mutex_init_done();)
os::Posix::init_2();
Linux::fast_thread_clock_init();
if (PosixSignals::init() == JNI_ERR) {
return JNI_ERR;
}
// Check and sets minimum stack sizes against command line options
if (set_minimum_stack_sizes() == JNI_ERR) {
return JNI_ERR;
}
#if defined(IA32) && !defined(ZERO)
// Need to ensure we've determined the process's initial stack to
// perform the workaround
Linux::capture_initial_stack(JavaThread::stack_size_at_create());
workaround_expand_exec_shield_cs_limit();
#else
suppress_primordial_thread_resolution = Arguments::created_by_java_launcher();
if (!suppress_primordial_thread_resolution) {
Linux::capture_initial_stack(JavaThread::stack_size_at_create());
}
#endif
Linux::libpthread_init();
Linux::sched_getcpu_init();
log_info(os)("HotSpot is running with %s, %s",
Linux::libc_version(), Linux::libpthread_version());
#ifdef __GLIBC__
// Check if we need to adjust the stack size for glibc guard pages.
init_adjust_stacksize_for_guard_pages();
#endif
if (UseNUMA || UseNUMAInterleaving) {
Linux::numa_init();
}
if (MaxFDLimit) {
// set the number of file descriptors to max. print out error
// if getrlimit/setrlimit fails but continue regardless.
struct rlimit nbr_files;
int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
if (status != 0) {
log_info(os)("os::init_2 getrlimit failed: %s", os::strerror(errno));
} else {
nbr_files.rlim_cur = nbr_files.rlim_max;
status = setrlimit(RLIMIT_NOFILE, &nbr_files);
if (status != 0) {
log_info(os)("os::init_2 setrlimit failed: %s", os::strerror(errno));
}
}
}
// at-exit methods are called in the reverse order of their registration.
// atexit functions are called on return from main or as a result of a
// call to exit(3C). There can be only 32 of these functions registered
// and atexit() does not set errno.
if (PerfAllowAtExitRegistration) {
// only register atexit functions if PerfAllowAtExitRegistration is set.
// atexit functions can be delayed until process exit time, which
// can be problematic for embedded VM situations. Embedded VMs should
// call DestroyJavaVM() to assure that VM resources are released.
// note: perfMemory_exit_helper atexit function may be removed in
// the future if the appropriate cleanup code can be added to the
// VM_Exit VMOperation's doit method.
if (atexit(perfMemory_exit_helper) != 0) {
warning("os::init_2 atexit(perfMemory_exit_helper) failed");
}
}
// initialize thread priority policy
prio_init();
if (!FLAG_IS_DEFAULT(AllocateHeapAt)) {
set_coredump_filter(DAX_SHARED_BIT);
}
if (DumpPrivateMappingsInCore) {
set_coredump_filter(FILE_BACKED_PVT_BIT);
}
if (DumpSharedMappingsInCore) {
set_coredump_filter(FILE_BACKED_SHARED_BIT);
}
if (DumpPerfMapAtExit && FLAG_IS_DEFAULT(UseCodeCacheFlushing)) {
// Disable code cache flushing to ensure the map file written at
// exit contains all nmethods generated during execution.
FLAG_SET_DEFAULT(UseCodeCacheFlushing, false);
}
// Override the timer slack value if needed. The adjustment for the main
// thread will establish the setting for child threads, which would be
// most threads in JDK/JVM.
if (TimerSlack >= 0) {
if (prctl(PR_SET_TIMERSLACK, TimerSlack) < 0) {
vm_exit_during_initialization("Setting timer slack failed: %s", os::strerror(errno));
}
}
return JNI_OK;
}
// older glibc versions don't have this macro (which expands to
// an optimized bit-counting function) so we have to roll our own
#ifndef CPU_COUNT
static int _cpu_count(const cpu_set_t* cpus) {
int count = 0;
// only look up to the number of configured processors
for (int i = 0; i < os::processor_count(); i++) {
if (CPU_ISSET(i, cpus)) {
count++;
}
}
return count;
}
#define CPU_COUNT(cpus) _cpu_count(cpus)
#endif // CPU_COUNT
// Get the current number of available processors for this process.
// This value can change at any time during a process's lifetime.
// sched_getaffinity gives an accurate answer as it accounts for cpusets.
// If it appears there may be more than 1024 processors then we do a
// dynamic check - see 6515172 for details.
// If anything goes wrong we fallback to returning the number of online
// processors - which can be greater than the number available to the process.
static int get_active_processor_count() {
// Note: keep this function, with its CPU_xx macros, *outside* the os namespace (see JDK-8289477).
cpu_set_t cpus; // can represent at most 1024 (CPU_SETSIZE) processors
cpu_set_t* cpus_p = &cpus;
size_t cpus_size = sizeof(cpu_set_t);
int configured_cpus = os::processor_count(); // upper bound on available cpus
int cpu_count = 0;
// old build platforms may not support dynamic cpu sets
#ifdef CPU_ALLOC
// To enable easy testing of the dynamic path on different platforms we
// introduce a diagnostic flag: UseCpuAllocPath
if (configured_cpus >= CPU_SETSIZE || UseCpuAllocPath) {
// kernel may use a mask bigger than cpu_set_t
log_trace(os)("active_processor_count: using dynamic path %s"
"- configured processors: %d",
UseCpuAllocPath ? "(forced) " : "",
configured_cpus);
cpus_p = CPU_ALLOC(configured_cpus);
if (cpus_p != nullptr) {
cpus_size = CPU_ALLOC_SIZE(configured_cpus);
// zero it just to be safe
CPU_ZERO_S(cpus_size, cpus_p);
}
else {
// failed to allocate so fallback to online cpus
int online_cpus = checked_cast<int>(::sysconf(_SC_NPROCESSORS_ONLN));
log_trace(os)("active_processor_count: "
"CPU_ALLOC failed (%s) - using "
"online processor count: %d",
os::strerror(errno), online_cpus);
return online_cpus;
}
}
else {
log_trace(os)("active_processor_count: using static path - configured processors: %d",
configured_cpus);
}
#else // CPU_ALLOC
// these stubs won't be executed
#define CPU_COUNT_S(size, cpus) -1
#define CPU_FREE(cpus)
log_trace(os)("active_processor_count: only static path available - configured processors: %d",
configured_cpus);
#endif // CPU_ALLOC
// pid 0 means the current thread - which we have to assume represents the process
if (sched_getaffinity(0, cpus_size, cpus_p) == 0) {
if (cpus_p != &cpus) { // can only be true when CPU_ALLOC used
cpu_count = CPU_COUNT_S(cpus_size, cpus_p);
}
else {
cpu_count = CPU_COUNT(cpus_p);
}
log_trace(os)("active_processor_count: sched_getaffinity processor count: %d", cpu_count);
}
else {
cpu_count = checked_cast<int>(::sysconf(_SC_NPROCESSORS_ONLN));
warning("sched_getaffinity failed (%s)- using online processor count (%d) "
"which may exceed available processors", os::strerror(errno), cpu_count);
}
if (cpus_p != &cpus) { // can only be true when CPU_ALLOC used
CPU_FREE(cpus_p);
}
assert(cpu_count > 0 && cpu_count <= os::processor_count(), "sanity check");
return cpu_count;
}
int os::Linux::active_processor_count() {
return get_active_processor_count();
}
// Determine the active processor count from one of
// three different sources:
//
// 1. User option -XX:ActiveProcessorCount
// 2. kernel os calls (sched_getaffinity or sysconf(_SC_NPROCESSORS_ONLN)
// 3. extracted from cgroup cpu subsystem (shares and quotas)
//
// Option 1, if specified, will always override.
// If the cgroup subsystem is active and configured, we
// will return the min of the cgroup and option 2 results.
// This is required since tools, such as numactl, that
// alter cpu affinity do not update cgroup subsystem
// cpuset configuration files.
int os::active_processor_count() {
// User has overridden the number of active processors
if (ActiveProcessorCount > 0) {
log_trace(os)("active_processor_count: "
"active processor count set by user : %d",
ActiveProcessorCount);
return ActiveProcessorCount;
}
int active_cpus;
if (OSContainer::is_containerized()) {
active_cpus = OSContainer::active_processor_count();
log_trace(os)("active_processor_count: determined by OSContainer: %d",
active_cpus);
} else {
active_cpus = os::Linux::active_processor_count();
}
return active_cpus;
}
static bool should_warn_invalid_processor_id() {
if (os::processor_count() == 1) {
// Don't warn if we only have one processor
return false;
}
static volatile int warn_once = 1;
if (Atomic::load(&warn_once) == 0 ||
Atomic::xchg(&warn_once, 0) == 0) {
// Don't warn more than once
return false;
}
return true;
}
uint os::processor_id() {
const int id = Linux::sched_getcpu();
if (id < processor_count()) {
return (uint)id;
}
// Some environments (e.g. openvz containers and the rr debugger) incorrectly
// report a processor id that is higher than the number of processors available.
// This is problematic, for example, when implementing CPU-local data structures,
// where the processor id is used to index into an array of length processor_count().
// If this happens we return 0 here. This is is safe since we always have at least
// one processor, but it's not optimal for performance if we're actually executing
// in an environment with more than one processor.
if (should_warn_invalid_processor_id()) {
log_warning(os)("Invalid processor id reported by the operating system "
"(got processor id %d, valid processor id range is 0-%d)",
id, processor_count() - 1);
log_warning(os)("Falling back to assuming processor id is 0. "
"This could have a negative impact on performance.");
}
return 0;
}
void os::set_native_thread_name(const char *name) {
if (Linux::_pthread_setname_np) {
char buf [16]; // according to glibc manpage, 16 chars incl. '/0'
snprintf(buf, sizeof(buf), "%s", name);
buf[sizeof(buf) - 1] = '\0';
const int rc = Linux::_pthread_setname_np(pthread_self(), buf);
// ERANGE should not happen; all other errors should just be ignored.
assert(rc != ERANGE, "pthread_setname_np failed");
}
}
////////////////////////////////////////////////////////////////////////////////
// debug support
bool os::find(address addr, outputStream* st) {
Dl_info dlinfo;
memset(&dlinfo, 0, sizeof(dlinfo));
if (dladdr(addr, &dlinfo) != 0) {
st->print(PTR_FORMAT ": ", p2i(addr));
if (dlinfo.dli_sname != nullptr && dlinfo.dli_saddr != nullptr) {
st->print("%s+" PTR_FORMAT, dlinfo.dli_sname,
p2i(addr) - p2i(dlinfo.dli_saddr));
} else if (dlinfo.dli_fbase != nullptr) {
st->print("<offset " PTR_FORMAT ">", p2i(addr) - p2i(dlinfo.dli_fbase));
} else {
st->print("<absolute address>");
}
if (dlinfo.dli_fname != nullptr) {
st->print(" in %s", dlinfo.dli_fname);
}
if (dlinfo.dli_fbase != nullptr) {
st->print(" at " PTR_FORMAT, p2i(dlinfo.dli_fbase));
}
st->cr();
if (Verbose) {
// decode some bytes around the PC
address begin = clamp_address_in_page(addr-40, addr, os::vm_page_size());
address end = clamp_address_in_page(addr+40, addr, os::vm_page_size());
address lowest = (address) dlinfo.dli_sname;
if (!lowest) lowest = (address) dlinfo.dli_fbase;
if (begin < lowest) begin = lowest;
Dl_info dlinfo2;
if (dladdr(end, &dlinfo2) != 0 && dlinfo2.dli_saddr != dlinfo.dli_saddr
&& end > dlinfo2.dli_saddr && dlinfo2.dli_saddr > begin) {
end = (address) dlinfo2.dli_saddr;
}
Disassembler::decode(begin, end, st);
}
return true;
}
return false;
}
////////////////////////////////////////////////////////////////////////////////
// misc
// This does not do anything on Linux. This is basically a hook for being
// able to use structured exception handling (thread-local exception filters)
// on, e.g., Win32.
void
os::os_exception_wrapper(java_call_t f, JavaValue* value, const methodHandle& method,
JavaCallArguments* args, JavaThread* thread) {
f(value, method, args, thread);
}
// This code originates from JDK's sysOpen and open64_w
// from src/solaris/hpi/src/system_md.c
int os::open(const char *path, int oflag, int mode) {
if (strlen(path) > MAX_PATH - 1) {
errno = ENAMETOOLONG;
return -1;
}
// All file descriptors that are opened in the Java process and not
// specifically destined for a subprocess should have the close-on-exec
// flag set. If we don't set it, then careless 3rd party native code
// might fork and exec without closing all appropriate file descriptors
// (e.g. as we do in closeDescriptors in UNIXProcess.c), and this in
// turn might:
//
// - cause end-of-file to fail to be detected on some file
// descriptors, resulting in mysterious hangs, or
//
// - might cause an fopen in the subprocess to fail on a system
// suffering from bug 1085341.
//
// (Yes, the default setting of the close-on-exec flag is a Unix
// design flaw)
//
// See:
// 1085341: 32-bit stdio routines should support file descriptors >255
// 4843136: (process) pipe file descriptor from Runtime.exec not being closed
// 6339493: (process) Runtime.exec does not close all file descriptors on Solaris 9
//
// Modern Linux kernels (after 2.6.23 2007) support O_CLOEXEC with open().
// O_CLOEXEC is preferable to using FD_CLOEXEC on an open file descriptor
// because it saves a system call and removes a small window where the flag
// is unset. On ancient Linux kernels the O_CLOEXEC flag will be ignored
// and we fall back to using FD_CLOEXEC (see below).
#ifdef O_CLOEXEC
oflag |= O_CLOEXEC;
#endif
int fd = ::open(path, oflag, mode);
if (fd == -1) return -1;
//If the open succeeded, the file might still be a directory
{
struct stat buf;
int ret = ::fstat(fd, &buf);
int st_mode = buf.st_mode;
if (ret != -1) {
if ((st_mode & S_IFMT) == S_IFDIR) {
errno = EISDIR;
::close(fd);
return -1;
}
} else {
::close(fd);
return -1;
}
}
#ifdef FD_CLOEXEC
// Validate that the use of the O_CLOEXEC flag on open above worked.
// With recent kernels, we will perform this check exactly once.
static sig_atomic_t O_CLOEXEC_is_known_to_work = 0;
if (!O_CLOEXEC_is_known_to_work) {
int flags = ::fcntl(fd, F_GETFD);
if (flags != -1) {
if ((flags & FD_CLOEXEC) != 0)
O_CLOEXEC_is_known_to_work = 1;
else
::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
}
}
#endif
return fd;
}
static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time);
static jlong fast_cpu_time(Thread *thread) {
clockid_t clockid;
int rc = os::Linux::pthread_getcpuclockid(thread->osthread()->pthread_id(),
&clockid);
if (rc == 0) {
return os::Linux::fast_thread_cpu_time(clockid);
} else {
// It's possible to encounter a terminated native thread that failed
// to detach itself from the VM - which should result in ESRCH.
assert_status(rc == ESRCH, rc, "pthread_getcpuclockid failed");
return -1;
}
}
// current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
// are used by JVM M&M and JVMTI to get user+sys or user CPU time
// of a thread.
//
// current_thread_cpu_time() and thread_cpu_time(Thread*) returns
// the fast estimate available on the platform.
jlong os::current_thread_cpu_time() {
if (os::Linux::supports_fast_thread_cpu_time()) {
return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
} else {
// return user + sys since the cost is the same
return slow_thread_cpu_time(Thread::current(), true /* user + sys */);
}
}
jlong os::thread_cpu_time(Thread* thread) {
// consistent with what current_thread_cpu_time() returns
if (os::Linux::supports_fast_thread_cpu_time()) {
return fast_cpu_time(thread);
} else {
return slow_thread_cpu_time(thread, true /* user + sys */);
}
}
jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
return os::Linux::fast_thread_cpu_time(CLOCK_THREAD_CPUTIME_ID);
} else {
return slow_thread_cpu_time(Thread::current(), user_sys_cpu_time);
}
}
jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
if (user_sys_cpu_time && os::Linux::supports_fast_thread_cpu_time()) {
return fast_cpu_time(thread);
} else {
return slow_thread_cpu_time(thread, user_sys_cpu_time);
}
}
// -1 on error.
static jlong slow_thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
pid_t tid = thread->osthread()->thread_id();
char *s;
char stat[2048];
size_t statlen;
char proc_name[64];
int count;
long sys_time, user_time;
char cdummy;
int idummy;
long ldummy;
FILE *fp;
snprintf(proc_name, 64, "/proc/self/task/%d/stat", tid);
fp = os::fopen(proc_name, "r");
if (fp == nullptr) return -1;
statlen = fread(stat, 1, 2047, fp);
stat[statlen] = '\0';
fclose(fp);
// Skip pid and the command string. Note that we could be dealing with
// weird command names, e.g. user could decide to rename java launcher
// to "java 1.4.2 :)", then the stat file would look like
// 1234 (java 1.4.2 :)) R ... ...
// We don't really need to know the command string, just find the last
// occurrence of ")" and then start parsing from there. See bug 4726580.
s = strrchr(stat, ')');
if (s == nullptr) return -1;
// Skip blank chars
do { s++; } while (s && isspace((unsigned char) *s));
count = sscanf(s,"%c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
&cdummy, &idummy, &idummy, &idummy, &idummy, &idummy,
&ldummy, &ldummy, &ldummy, &ldummy, &ldummy,
&user_time, &sys_time);
if (count != 13) return -1;
if (user_sys_cpu_time) {
return ((jlong)sys_time + (jlong)user_time) * (1000000000 / os::Posix::clock_tics_per_second());
} else {
return (jlong)user_time * (1000000000 / os::Posix::clock_tics_per_second());
}
}
void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
info_ptr->max_value = all_bits_jlong; // will not wrap in less than 64 bits
info_ptr->may_skip_backward = false; // elapsed time not wall time
info_ptr->may_skip_forward = false; // elapsed time not wall time
info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
}
void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
info_ptr->max_value = all_bits_jlong; // will not wrap in less than 64 bits
info_ptr->may_skip_backward = false; // elapsed time not wall time
info_ptr->may_skip_forward = false; // elapsed time not wall time
info_ptr->kind = JVMTI_TIMER_TOTAL_CPU; // user+system time is returned
}
bool os::is_thread_cpu_time_supported() {
return true;
}
// System loadavg support. Returns -1 if load average cannot be obtained.
// Linux doesn't yet have a (official) notion of processor sets,
// so just return the system wide load average.
int os::loadavg(double loadavg[], int nelem) {
return ::getloadavg(loadavg, nelem);
}
// Get the default path to the core file
// Returns the length of the string
int os::get_core_path(char* buffer, size_t bufferSize) {
/*
* Max length of /proc/sys/kernel/core_pattern is 128 characters.
* See https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
*/
const int core_pattern_len = 129;
char core_pattern[core_pattern_len] = {0};
int core_pattern_file = ::open("/proc/sys/kernel/core_pattern", O_RDONLY);
if (core_pattern_file == -1) {
return -1;
}
ssize_t ret = ::read(core_pattern_file, core_pattern, core_pattern_len);
::close(core_pattern_file);
if (ret <= 0 || ret >= core_pattern_len || core_pattern[0] == '\n') {
return -1;
}
if (core_pattern[ret-1] == '\n') {
core_pattern[ret-1] = '\0';
} else {
core_pattern[ret] = '\0';
}
// Replace the %p in the core pattern with the process id. NOTE: we do this
// only if the pattern doesn't start with "|", and we support only one %p in
// the pattern.
char *pid_pos = strstr(core_pattern, "%p");
const char* tail = (pid_pos != nullptr) ? (pid_pos + 2) : ""; // skip over the "%p"
int written;
if (core_pattern[0] == '/') {
if (pid_pos != nullptr) {
*pid_pos = '\0';
written = jio_snprintf(buffer, bufferSize, "%s%d%s", core_pattern,
current_process_id(), tail);
} else {
written = jio_snprintf(buffer, bufferSize, "%s", core_pattern);
}
} else {
char cwd[PATH_MAX];
const char* p = get_current_directory(cwd, PATH_MAX);
if (p == nullptr) {
return -1;
}
if (core_pattern[0] == '|') {
written = jio_snprintf(buffer, bufferSize,
"\"%s\" (or dumping to %s/core.%d)",
&core_pattern[1], p, current_process_id());
} else if (pid_pos != nullptr) {
*pid_pos = '\0';
written = jio_snprintf(buffer, bufferSize, "%s/%s%d%s", p, core_pattern,
current_process_id(), tail);
} else {
written = jio_snprintf(buffer, bufferSize, "%s/%s", p, core_pattern);
}
}
if (written < 0) {
return -1;
}
if (((size_t)written < bufferSize) && (pid_pos == nullptr) && (core_pattern[0] != '|')) {
int core_uses_pid_file = ::open("/proc/sys/kernel/core_uses_pid", O_RDONLY);
if (core_uses_pid_file != -1) {
char core_uses_pid = 0;
ssize_t ret = ::read(core_uses_pid_file, &core_uses_pid, 1);
::close(core_uses_pid_file);
if (core_uses_pid == '1') {
jio_snprintf(buffer + written, bufferSize - written,
".%d", current_process_id());
}
}
}
return checked_cast<int>(strlen(buffer));
}
bool os::start_debugging(char *buf, int buflen) {
int len = (int)strlen(buf);
char *p = &buf[len];
jio_snprintf(p, buflen-len,
"\n\n"
"Do you want to debug the problem?\n\n"
"To debug, run 'gdb /proc/%d/exe %d'; then switch to thread %zu (" INTPTR_FORMAT ")\n"
"Enter 'yes' to launch gdb automatically (PATH must include gdb)\n"
"Otherwise, press RETURN to abort...",
os::current_process_id(), os::current_process_id(),
os::current_thread_id(), os::current_thread_id());
bool yes = os::message_box("Unexpected Error", buf);
if (yes) {
// yes, user asked VM to launch debugger
jio_snprintf(buf, sizeof(char)*buflen, "gdb /proc/%d/exe %d",
os::current_process_id(), os::current_process_id());
os::fork_and_exec(buf);
yes = false;
}
return yes;
}
// Java/Compiler thread:
//
// Low memory addresses
// P0 +------------------------+
// | |\ Java thread created by VM does not have glibc
// | glibc guard page | - guard page, attached Java thread usually has
// | |/ 1 glibc guard page.
// P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
// | |\
// | HotSpot Guard Pages | - red, yellow and reserved pages
// | |/
// +------------------------+ StackOverflow::stack_reserved_zone_base()
// | |\
// | Normal Stack | -
// | |/
// P2 +------------------------+ Thread::stack_base()
//
// Non-Java thread:
//
// Low memory addresses
// P0 +------------------------+
// | |\
// | glibc guard page | - usually 1 page
// | |/
// P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
// | |\
// | Normal Stack | -
// | |/
// P2 +------------------------+ Thread::stack_base()
//
// ** P1 (aka bottom) and size are the address and stack size
// returned from pthread_attr_getstack().
// ** P2 (aka stack top or base) = P1 + size
// ** If adjustStackSizeForGuardPages() is true the guard pages have been taken
// out of the stack size given in pthread_attr. We work around this for
// threads created by the VM. We adjust bottom to be P1 and size accordingly.
//
#ifndef ZERO
void os::current_stack_base_and_size(address* base, size_t* size) {
address bottom;
if (os::is_primordial_thread()) {
// primordial thread needs special handling because pthread_getattr_np()
// may return bogus value.
bottom = os::Linux::initial_thread_stack_bottom();
*size = os::Linux::initial_thread_stack_size();
*base = bottom + *size;
} else {
pthread_attr_t attr;
int rslt = pthread_getattr_np(pthread_self(), &attr);
// JVM needs to know exact stack location, abort if it fails
if (rslt != 0) {
if (rslt == ENOMEM) {
vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
} else {
fatal("pthread_getattr_np failed with error = %d", rslt);
}
}
if (pthread_attr_getstack(&attr, (void **)&bottom, size) != 0) {
fatal("Cannot locate current stack attributes!");
}
*base = bottom + *size;
if (os::Linux::adjustStackSizeForGuardPages()) {
size_t guard_size = 0;
rslt = pthread_attr_getguardsize(&attr, &guard_size);
if (rslt != 0) {
fatal("pthread_attr_getguardsize failed with error = %d", rslt);
}
bottom += guard_size;
*size -= guard_size;
}
pthread_attr_destroy(&attr);
}
assert(os::current_stack_pointer() >= bottom &&
os::current_stack_pointer() < *base, "just checking");
}
#endif
static inline struct timespec get_mtime(const char* filename) {
struct stat st;
int ret = os::stat(filename, &st);
assert(ret == 0, "failed to stat() file '%s': %s", filename, os::strerror(errno));
return st.st_mtim;
}
int os::compare_file_modified_times(const char* file1, const char* file2) {
struct timespec filetime1 = get_mtime(file1);
struct timespec filetime2 = get_mtime(file2);
int diff = primitive_compare(filetime1.tv_sec, filetime2.tv_sec);
if (diff == 0) {
diff = primitive_compare(filetime1.tv_nsec, filetime2.tv_nsec);
}
return diff;
}
bool os::supports_map_sync() {
return true;
}
void os::print_memory_mappings(char* addr, size_t bytes, outputStream* st) {
// Note: all ranges are "[..)"
unsigned long long start = (unsigned long long)addr;
unsigned long long end = start + bytes;
FILE* f = os::fopen("/proc/self/maps", "r");
int num_found = 0;
if (f != nullptr) {
st->print_cr("Range [%llx-%llx) contains: ", start, end);
char line[512];
while(fgets(line, sizeof(line), f) == line) {
unsigned long long segment_start = 0;
unsigned long long segment_end = 0;
if (::sscanf(line, "%llx-%llx", &segment_start, &segment_end) == 2) {
// Lets print out every range which touches ours.
if (segment_start < end && segment_end > start) {
num_found ++;
st->print("%s", line); // line includes \n
}
}
}
::fclose(f);
if (num_found == 0) {
st->print_cr("nothing.");
}
}
}
#ifdef __GLIBC__
void os::Linux::get_mallinfo(glibc_mallinfo* out, bool* might_have_wrapped) {
if (g_mallinfo2) {
new_mallinfo mi = g_mallinfo2();
out->arena = mi.arena;
out->ordblks = mi.ordblks;
out->smblks = mi.smblks;
out->hblks = mi.hblks;
out->hblkhd = mi.hblkhd;
out->usmblks = mi.usmblks;
out->fsmblks = mi.fsmblks;
out->uordblks = mi.uordblks;
out->fordblks = mi.fordblks;
out->keepcost = mi.keepcost;
*might_have_wrapped = false;
} else if (g_mallinfo) {
old_mallinfo mi = g_mallinfo();
// glibc reports unsigned 32-bit sizes in int form. First make unsigned, then extend.
out->arena = (size_t)(unsigned)mi.arena;
out->ordblks = (size_t)(unsigned)mi.ordblks;
out->smblks = (size_t)(unsigned)mi.smblks;
out->hblks = (size_t)(unsigned)mi.hblks;
out->hblkhd = (size_t)(unsigned)mi.hblkhd;
out->usmblks = (size_t)(unsigned)mi.usmblks;
out->fsmblks = (size_t)(unsigned)mi.fsmblks;
out->uordblks = (size_t)(unsigned)mi.uordblks;
out->fordblks = (size_t)(unsigned)mi.fordblks;
out->keepcost = (size_t)(unsigned)mi.keepcost;
*might_have_wrapped = NOT_LP64(false) LP64_ONLY(true);
} else {
// We should have either mallinfo or mallinfo2
ShouldNotReachHere();
}
}
int os::Linux::malloc_info(FILE* stream) {
if (g_malloc_info == nullptr) {
return -2;
}
return g_malloc_info(0, stream);
}
#endif // __GLIBC__
bool os::trim_native_heap(os::size_change_t* rss_change) {
#ifdef __GLIBC__
os::Linux::meminfo_t info1;
os::Linux::meminfo_t info2;
bool have_info1 = rss_change != nullptr &&
os::Linux::query_process_memory_info(&info1);
::malloc_trim(0);
bool have_info2 = rss_change != nullptr && have_info1 &&
os::Linux::query_process_memory_info(&info2);
ssize_t delta = (ssize_t) -1;
if (rss_change != nullptr) {
if (have_info1 && have_info2 &&
info1.vmrss != -1 && info2.vmrss != -1 &&
info1.vmswap != -1 && info2.vmswap != -1) {
// Note: query_process_memory_info returns values in K
rss_change->before = (info1.vmrss + info1.vmswap) * K;
rss_change->after = (info2.vmrss + info2.vmswap) * K;
} else {
rss_change->after = rss_change->before = SIZE_MAX;
}
}
return true;
#else
return false; // musl
#endif
}
bool os::pd_dll_unload(void* libhandle, char* ebuf, int ebuflen) {
if (ebuf && ebuflen > 0) {
ebuf[0] = '\0';
ebuf[ebuflen - 1] = '\0';
}
bool res = (0 == ::dlclose(libhandle));
if (!res) {
// error analysis when dlopen fails
const char* error_report = ::dlerror();
if (error_report == nullptr) {
error_report = "dlerror returned no error description";
}
if (ebuf != nullptr && ebuflen > 0) {
snprintf(ebuf, ebuflen - 1, "%s", error_report);
}
}
return res;
} // end: os::pd_dll_unload()