tools/jprof/elf.cpp
author Mike Hommey <mh+mozilla@glandium.org>
Fri, 05 Apr 2019 02:30:56 +0000
changeset 468491 60669a841a87644ba9b2f4d9f17f225e2eca0980
parent 454538 5f4630838d46dd81dadb13220a4af0da9e23a619
child 472073 e1993a1f09ac53cd1a04fdf6a87f8cad8e44f73e
permissions -rw-r--r--
Bug 1541792 - Replace linker magic with manual component registration. r=froydnj Before bug 938437, we had a rather large and error-prone nsStaticXULComponents.cpp used to register all modules. That was replaced with clever use of the linker, which allowed to avoid the mess that maintaining that file was. Fast forward to now, where after bug 1524687 and other work that preceded it, we have a much smaller number of remaining static xpcom components, registered via this linker hack, and don't expect to add any new ones. The list should eventually go down to zero. Within that context, it seems to be the right time to get rid of the magic, and with it the problems it causes on its own. Some of those components could probably be trivially be converted to static registration via .conf files, but I didn't want to deal with the possible need to increase the number of dummy modules in XPCOMInit.cpp. They can still be converted as a followup. Differential Revision: https://phabricator.services.mozilla.com/D26076

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "leaky.h"

#ifdef USE_ELF

#  include "leaky.h"
#  include <stdio.h>
#  include <malloc.h>
#  include <libelf/libelf.h>
#  include <unistd.h>
#  include <fcntl.h>
#  include <string.h>

void leaky::readSymbols(const char *fileName) {
  int fd = ::open(fileName, O_RDONLY);
  if (fd < 0) {
    fprintf(stderr, "%s: unable to open \"%s\"\n", applicationName, fileName);
    exit(-1);
  }

  elf_version(EV_CURRENT);
  Elf *elf = elf_begin(fd, ELF_C_READ, 0);
  if (!elf) {
    fprintf(stderr, "%s: \"%s\": has no symbol table\n", applicationName,
            fileName);
    exit(-1);
  }

  long alloced = 10000;
  Symbol *syms = (Symbol *)malloc(sizeof(Symbol) * 10000);
  Symbol *sp = syms;
  Symbol *last = syms + alloced;

  // Get each of the relevant sections and add them to the list of
  // symbols.
  Elf32_Ehdr *ehdr = elf32_getehdr(elf);
  if (!ehdr) {
    fprintf(stderr, "%s: elf library lossage\n", applicationName);
    exit(-1);
  }
#  if 0
    Elf32_Half ndx = ehdr->e_shstrndx;
#  endif

  Elf_Scn *scn = 0;
  int strtabndx = -1;
  for (int i = 1; (scn = elf_nextscn(elf, scn)) != 0; i++) {
    Elf32_Shdr *shdr = elf32_getshdr(scn);
#  if 0
	char *name = elf_strptr(elf, ndx, (size_t) shdr->sh_name);
	printf("Section %s (%d 0x%x)\n", name ? name : "(null)",
	       shdr->sh_type, shdr->sh_type);
#  endif
    if (shdr->sh_type == SHT_STRTAB) {
      /* We assume here that string tables preceed symbol tables... */
      strtabndx = i;
      continue;
    }
#  if 0
	if (shdr->sh_type == SHT_DYNAMIC) {
	    /* Dynamic */
	    Elf_Data *data = elf_getdata(scn, 0);
	    if (!data || !data->d_size) {
		printf("No data...");
		continue;
	    }

	    Elf32_Dyn *dyn = (Elf32_Dyn*) data->d_buf;
	    Elf32_Dyn *lastdyn =
		(Elf32_Dyn*) ((char*) data->d_buf + data->d_size);
	    for (; dyn < lastdyn; dyn++) {
		printf("tag=%d value=0x%x\n", dyn->d_tag, dyn->d_un.d_val);
	    }
	} else
#  endif
    if ((shdr->sh_type == SHT_SYMTAB) || (shdr->sh_type == SHT_DYNSYM)) {
      /* Symbol table */
      Elf_Data *data = elf_getdata(scn, 0);
      if (!data || !data->d_size) {
        printf("No data...");
        continue;
      }

      /* In theory we now have the symbols... */
      Elf32_Sym *esym = (Elf32_Sym *)data->d_buf;
      Elf32_Sym *lastsym = (Elf32_Sym *)((char *)data->d_buf + data->d_size);
      for (; esym < lastsym; esym++) {
#  if 0
		char *nm = elf_strptr(elf, strtabndx, (size_t)esym->st_name);
		printf("%20s 0x%08x %02x %02x\n",
		       nm, esym->st_value, ELF32_ST_BIND(esym->st_info),
		       ELF32_ST_TYPE(esym->st_info));
#  endif
        if ((esym->st_value == 0) ||
            (ELF32_ST_BIND(esym->st_info) == STB_WEAK) ||
            (ELF32_ST_BIND(esym->st_info) == STB_NUM) ||
            (ELF32_ST_TYPE(esym->st_info) != STT_FUNC)) {
          continue;
        }
#  if 1
        char *nm = elf_strptr(elf, strtabndx, (size_t)esym->st_name);
#  endif
        sp->name = nm ? strdup(nm) : "(no name)";
        sp->address = esym->st_value;
        sp++;
        if (sp >= last) {
          long n = alloced + 10000;
          syms = (Symbol *)realloc(syms, (size_t)(sizeof(Symbol) * n));
          last = syms + n;
          sp = syms + alloced;
          alloced = n;
        }
      }
    }
  }

  int interesting = sp - syms;
  if (!quiet) {
    printf("Total of %d symbols\n", interesting);
  }
  usefulSymbols = interesting;
  externalSymbols = syms;
}

#endif /* USE_ELF */