src/hotspot/os/aix/loadlib_aix.cpp

/*
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 * Copyright (c) 2022, IBM Corp.
 * 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
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// Implementation of LoadedLibraries and friends

// Ultimately this just uses loadquery()
// See:
// http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp
//      ?topic=/com.ibm.aix.basetechref/doc/basetrf1/loadquery.htm

#include "loadlib_aix.hpp"
#include "misc_aix.hpp"
#include "porting_aix.hpp"
#include "logging/log.hpp"
#include "utilities/debug.hpp"
#include "utilities/ostream.hpp"
#include "utilities/permitForbiddenFunctions.hpp"

// For loadquery()
#include <sys/ldr.h>

// For getargs()
#include <procinfo.h>

// Use raw malloc instead of os::malloc - this code gets used for error reporting.

// A class to "intern" eternal strings.
// TODO: similar coding exists in AIX version of dladdr and potentially elsewhere: consolidate!
class StringList {

  char** _list;
  int _cap;
  int _num;

  // Enlarge list. If oom, leave old list intact and return false.
  bool enlarge() {
    int cap2 = _cap + 64;
    char** l2 = (char**) permit_forbidden_function::realloc(_list, sizeof(char*) * cap2);
    if (!l2) {
      return false;
    }
    _list = l2;
    _cap = cap2;
    return true;
  }

  // Append string to end of list.
  // Returns null if oom.
  char* append(const char* s) {
    if (_cap == _num) {
      if (!enlarge()) {
        return nullptr;
      }
    }
    assert0(_cap > _num);
    char* s2 = permit_forbidden_function::strdup(s);
    if (!s2) {
      return nullptr;
    }
    _list[_num] = s2;
    trcVerbose("StringDir: added %s at pos %d", s2, _num);
    _num ++;
    return s2;
  }

public:

  StringList()
    : _list(nullptr)
    , _cap(0)
    , _num(0)
  {}

  // String is copied into the list; pointer to copy is returned.
  // Returns null if oom.
  char* add (const char* s) {
    for (int i = 0; i < _num; i++) {
      if (strcmp(_list[i], s) == 0) {
        return _list[i];
      }
    }
    return append(s);
  }

};

static StringList g_stringlist;

//////////////////////

// Entries are kept in a linked list ordered by text address. Entries are not
// eternal - this list is rebuilt on every reload.
// Note that we do not hand out those entries, but copies of them.

static void print_entry(const loaded_module_t* lm, outputStream* os) {
  os->print(" %c text: " INTPTR_FORMAT " - " INTPTR_FORMAT
            ", data: " INTPTR_FORMAT " - " INTPTR_FORMAT " "
            "%s",
      (lm->is_in_vm ? '*' : ' '),
      p2i(lm->text), (uintptr_t)lm->text + lm->text_len,
      p2i(lm->data), (uintptr_t)lm->data + lm->data_len,
      lm->path);
  if (lm->member) {
    os->print("(%s)", lm->member);
  }
}

static loaded_module_t* g_first = nullptr;

static loaded_module_t* find_entry_for_text_address(const void* p) {
  for (loaded_module_t* lm = g_first; lm; lm = lm->next) {
    if ((uintptr_t)p >= (uintptr_t)lm->text &&
        (uintptr_t)p < ((uintptr_t)lm->text + lm->text_len)) {
      return lm;
    }
  }
  return nullptr;
}

static loaded_module_t* find_entry_for_data_address(const void* p) {
  for (loaded_module_t* lm = g_first; lm; lm = lm->next) {
    if ((uintptr_t)p >= (uintptr_t)lm->data &&
        (uintptr_t)p < ((uintptr_t)lm->data + lm->data_len)) {
      return lm;
    }
  }
  return nullptr;
}

// Adds a new entry to the list (ordered by text address ascending).
static void add_entry_to_list(loaded_module_t* lm, loaded_module_t** start) {
  loaded_module_t* last = nullptr;
  loaded_module_t* lm2 = *start;
  while (lm2 && lm2->text < lm->text) {
    last = lm2;
    lm2 = lm2->next;
  }
  if (last) {
    last->next = lm;
  } else {
    *start = lm;
  }
  lm->next = lm2;
}

static void free_entry_list(loaded_module_t** start) {
  loaded_module_t* lm = *start;
  while (lm) {
    loaded_module_t* const lm2 = lm->next;
    permit_forbidden_function::free(lm);
    lm = lm2;
  }
  *start = nullptr;
}


// Rebuild the internal module table. If an error occurs, old table remains
// unchanged.
static bool reload_table() {

  bool rc = false;

  trcVerbose("reload module table...");

  loaded_module_t* new_list = nullptr;
  const struct ld_info* ldi = nullptr;

  // Call loadquery(L_GETINFO..) to get a list of all loaded Dlls from AIX. loadquery
  // requires a large enough buffer.
  uint8_t* buffer = nullptr;
  size_t buflen = 1024;
  for (;;) {
    buffer = (uint8_t*) permit_forbidden_function::realloc(buffer, buflen);
    if (loadquery(L_GETINFO, buffer, buflen) == -1) {
      if (errno == ENOMEM) {
        buflen *= 2;
      } else {
        log_warning(os)("loadquery failed (%d)", errno);
        goto cleanup;
      }
    } else {
      break;
    }
  }

  trcVerbose("loadquery buffer size is %zu.", buflen);

  // the entry for the executable itself does not contain a path.
  // instead we retrieve the path of the executable with the getargs API.
  static char pgmpath[PATH_MAX+1] = "";
  static char* pgmbase = nullptr;
  if (pgmpath[0] == 0) {
    procentry64 PInfo;
    PInfo.pi_pid = ::getpid();
    if (0 == ::getargs(&PInfo, sizeof(PInfo), (char*)pgmpath, PATH_MAX) && *pgmpath) {
      pgmpath[PATH_MAX] = '\0';
      pgmbase = strrchr(pgmpath, '/');
      if (pgmbase != nullptr) {
        pgmbase += 1;
      }
    }
  }

  // Iterate over the loadquery result. For details see sys/ldr.h on AIX.
  ldi = (struct ld_info*) buffer;

  for (;;) {

    loaded_module_t* lm = (loaded_module_t*) permit_forbidden_function::malloc(sizeof(loaded_module_t));
    if (!lm) {
      log_warning(os)("OOM.");
      goto cleanup;
    }

    memset(lm, 0, sizeof(loaded_module_t));

    lm->text     = ldi->ldinfo_textorg;
    lm->text_len = ldi->ldinfo_textsize;
    lm->data     = ldi->ldinfo_dataorg;
    lm->data_len = ldi->ldinfo_datasize;

    if (pgmbase != nullptr && 0 == strcmp(pgmbase, ldi->ldinfo_filename)) {
      lm->path = g_stringlist.add(pgmpath);
    } else {
      lm->path = g_stringlist.add(ldi->ldinfo_filename);
    }

    if (!lm->path) {
      log_warning(os)("OOM.");
      permit_forbidden_function::free(lm);
      goto cleanup;
    }

    // Extract short name
    {
      const char* p = strrchr(lm->path, '/');
      if (p) {
        p ++;
        lm->shortname = p;
      } else {
        lm->shortname = lm->path;
      }
    }

    // Do we have a member name as well (see ldr.h)?
    const char* p_mbr_name =
      ldi->ldinfo_filename + strlen(ldi->ldinfo_filename) + 1;
    if (*p_mbr_name) {
      lm->member = g_stringlist.add(p_mbr_name);
      if (!lm->member) {
        log_warning(os)("OOM.");
        permit_forbidden_function::free(lm);
        goto cleanup;
      }
    } else {
      lm->member = nullptr;
    }

    if (strcmp(lm->shortname, "libjvm.so") == 0) {
      // Note that this, theoretically, is fuzzy. We may accidentally contain
      // more than one libjvm.so. But that is improbable, so lets go with this
      // solution.
      lm->is_in_vm = true;
    }

    trcVerbose("entry: %p %zu, %p %zu, %s %s %s, %d",
      lm->text, lm->text_len,
      lm->data, lm->data_len,
      lm->path, lm->shortname,
      (lm->member ? lm->member : "null"),
      lm->is_in_vm
    );

    // Add to list.
    add_entry_to_list(lm, &new_list);

    // Next entry...
    if (ldi->ldinfo_next) {
      ldi = (struct ld_info*)(((char*)ldi) + ldi->ldinfo_next);
    } else {
      break;
    }
  }

  // We are done. All is well. Free old list and swap to new one.
  if (g_first) {
    free_entry_list(&g_first);
  }
  g_first = new_list;
  new_list = nullptr;

  rc = true;

cleanup:

  if (new_list) {
    free_entry_list(&new_list);
  }

  permit_forbidden_function::free(buffer);

  return rc;

} // end LoadedLibraries::reload()

// Callback for loaded module information (from os.hpp)
// Input parameters:
//    char*     module_file_name,
//    address   module_base_addr,
//    address   module_top_addr,
//    void*     param
static bool for_each_internal(os::LoadedModulesCallbackFunc cb, void* param) {

  for (const loaded_module_t* lm = g_first; lm; lm = lm->next) {
    (*cb)(lm->shortname,
          (address) lm->text,
          (address) lm->text + lm->text_len,
          param);
  }

  return true;
}

///////////////////////////////////////////////////////////////////////////////
// Externals

static MiscUtils::CritSect g_cs;

// Rebuild the internal module table. If an error occurs, old table remains
// unchanged.
bool LoadedLibraries::reload() {
  MiscUtils::AutoCritSect lck(&g_cs);
  return reload_table();
}

void LoadedLibraries::print(outputStream* os) {
  MiscUtils::AutoCritSect lck(&g_cs);
  if (!g_first) {
    reload_table();
  }
  for (loaded_module_t* lm = g_first; lm; lm = lm->next) {
    print_entry(lm, os);
    os->cr();
  }
}

bool LoadedLibraries::find_for_text_address(const void* p,
                                            loaded_module_t* info) {
  MiscUtils::AutoCritSect lck(&g_cs);
  if (!g_first) {
    reload_table();
  }

  const loaded_module_t* const lm = find_entry_for_text_address(p);
  if (!lm) {
    return false;
  }

  if (info) {
    memcpy(info, lm, sizeof(loaded_module_t));
    info->next = nullptr;
  }
  return true;
}


bool LoadedLibraries::find_for_data_address (
  const void* p,
  loaded_module_t* info // optional. can be null:
) {
  MiscUtils::AutoCritSect lck(&g_cs);
  if (!g_first) {
    reload_table();
  }

  const loaded_module_t* const lm = find_entry_for_data_address(p);
  if (!lm) {
    return false;
  }

  if (info) {
    memcpy(info, lm, sizeof(loaded_module_t));
    info->next = nullptr;
  }
  return true;
}

bool LoadedLibraries::for_each(os::LoadedModulesCallbackFunc cb, void* param) {
  MiscUtils::AutoCritSect lck(&g_cs);

  if (!g_first) {
    if (!reload_table()) {
      // If the table is not loaded and cannot be initialized,
      // then we must quit.
      return false;
    }
  }

  return for_each_internal(cb, param);
}