| /* Get frequency of the system processor. powerpc/Linux version. |
| Copyright (C) 2000-2018 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <ctype.h> |
| #include <fcntl.h> |
| #include <stdint.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include <sysdep.h> |
| #include <libc-vdso.h> |
| #include <not-cancel.h> |
| |
| #if defined __clang__ && defined __powerpc64__ |
| /* On ppc, __get_clockfreq's body eventually expands into asm code |
| that does a bctrl, but clang does not recognize the need to save |
| the link register, so calls loop infinitely instead of returning. |
| As workaround, make a dummy function call that forces a link |
| register save. */ |
| volatile int get_clockfreq_dummy_glob; |
| |
| void __attribute__((noinline)) get_clockfreq_dummy () |
| { |
| get_clockfreq_dummy_glob = 45; |
| } |
| #endif |
| |
| hp_timing_t |
| __get_clockfreq (void) |
| { |
| hp_timing_t result = 0L; |
| |
| #if defined __clang__ && defined __powerpc64__ |
| get_clockfreq_dummy (); |
| #endif |
| |
| #ifdef SHARED |
| /* The vDSO does not return an error (it clear cr0.so on returning). */ |
| INTERNAL_SYSCALL_DECL (err); |
| result = |
| INTERNAL_VSYSCALL_NO_SYSCALL_FALLBACK (get_tbfreq, err, uint64_t, 0); |
| #else |
| /* We read the information from the /proc filesystem. /proc/cpuinfo |
| contains at least one line like: |
| timebase : 33333333 |
| We search for this line and convert the number into an integer. */ |
| int fd = __open_nocancel ("/proc/cpuinfo", O_RDONLY); |
| if (__glibc_unlikely (fd == -1)) |
| return result; |
| |
| /* The timebase will be in the 1st 1024 bytes for systems with up |
| to 8 processors. If the first read returns less then 1024 |
| bytes read, we have the whole cpuinfo and can start the scan. |
| Otherwise we will have to read more to insure we have the |
| timebase value in the scan. */ |
| char buf[1024]; |
| ssize_t n; |
| |
| n = __read_nocancel (fd, buf, sizeof (buf)); |
| if (n == sizeof (buf)) |
| { |
| /* We are here because the 1st read returned exactly sizeof |
| (buf) bytes. This implies that we are not at EOF and may |
| not have read the timebase value yet. So we need to read |
| more bytes until we know we have EOF. We copy the lower |
| half of buf to the upper half and read sizeof (buf)/2 |
| bytes into the lower half of buf and repeat until we |
| reach EOF. We can assume that the timebase will be in |
| the last 512 bytes of cpuinfo, so two 512 byte half_bufs |
| will be sufficient to contain the timebase and will |
| handle the case where the timebase spans the half_buf |
| boundry. */ |
| const ssize_t half_buf = sizeof (buf) / 2; |
| while (n >= half_buf) |
| { |
| memcpy (buf, buf + half_buf, half_buf); |
| n = __read_nocancel (fd, buf + half_buf, half_buf); |
| } |
| if (n >= 0) |
| n += half_buf; |
| } |
| __close_nocancel (fd); |
| |
| if (__glibc_likely (n > 0)) |
| { |
| char *mhz = memmem (buf, n, "timebase", 7); |
| |
| if (__glibc_likely (mhz != NULL)) |
| { |
| char *endp = buf + n; |
| |
| /* Search for the beginning of the string. */ |
| while (mhz < endp && (*mhz < '0' || *mhz > '9') && *mhz != '\n') |
| ++mhz; |
| |
| while (mhz < endp && *mhz != '\n') |
| { |
| if (*mhz >= '0' && *mhz <= '9') |
| { |
| result *= 10; |
| result += *mhz - '0'; |
| } |
| |
| ++mhz; |
| } |
| } |
| } |
| #endif |
| |
| return result; |
| } |