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perf symbol: Fix symbol parsing in certain cases: use the build-id as a symlink

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In some cases distros have binaries and debuginfo in weird places:

[root@doppio tuna]# ls -la /usr/lib64/{xulrunner-1.9.1/xulrunner-stub,firefox-3.5.2/firefox}
-rwxr-xr-x 1 root root 90024 2009-08-03 19:45 /usr/lib64/firefox-3.5.2/firefox
-rwxr-xr-x 1 root root 90024 2009-08-03 18:23 /usr/lib64/xulrunner-1.9.1/xulrunner-stub
[root@doppio tuna]# sha1sum /usr/lib64/{xulrunner-1.9.1/xulrunner-stub,firefox-3.5.2/firefox}
19a858077d263d5de22c9c5da250d3e4396ae739  /usr/lib64/xulrunner-1.9.1/xulrunner-stub
19a858077d263d5de22c9c5da250d3e4396ae739  /usr/lib64/firefox-3.5.2/firefox
[root@doppio tuna]# rpm -qf /usr/lib64/{xulrunner-1.9.1/xulrunner-stub,firefox-3.5.2/firefox}
xulrunner-1.9.1.2-1.fc11.x86_64
firefox-3.5.2-2.fc11.x86_64
[root@doppio tuna]# ls -la /usr/lib/debug/{usr/lib64/xulrunner-1.9.1/xulrunner-stub,usr/lib64/firefox-3.5.2/firefox}.debug
ls: cannot access /usr/lib/debug/usr/lib64/firefox-3.5.2/firefox.debug: No such file or directory
-rwxr-xr-x 1 root root 403608 2009-08-03 18:22 /usr/lib/debug/usr/lib64/xulrunner-1.9.1/xulrunner-stub.debug

Seemingly we don't have a .symtab when we actually can find it
if we use the .note.gnu.build-id ELF section put in place by
some distros. Use it and find the symbols we need.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arnaldo Carvalho de Melo 2009-08-05 19:02:49 -03:00 committed by Ingo Molnar
parent e0d82a0a4e
commit 4d1e00a8af
1 changed files with 73 additions and 3 deletions
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76
tools/perf/util/symbol.c
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@ -661,10 +661,69 @@ static int dso__load_sym(struct dso *self, int fd, const char *name,
return err;
}
#define BUILD_ID_SIZE 128
static char *dso__read_build_id(struct dso *self, int verbose)
{
int i;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
Elf_Data *build_id_data;
Elf_Scn *sec;
char *build_id = NULL, *bid;
unsigned char *raw;
Elf *elf;
int fd = open(self->name, O_RDONLY);
if (fd < 0)
goto out;
elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
if (elf == NULL) {
if (verbose)
fprintf(stderr, "%s: cannot read %s ELF file.\n",
__func__, self->name);
goto out_close;
}
if (gelf_getehdr(elf, &ehdr) == NULL) {
if (verbose)
fprintf(stderr, "%s: cannot get elf header.\n", __func__);
goto out_elf_end;
}
sec = elf_section_by_name(elf, &ehdr, &shdr, ".note.gnu.build-id", NULL);
if (sec == NULL)
goto out_elf_end;
build_id_data = elf_getdata(sec, NULL);
if (build_id_data == NULL)
goto out_elf_end;
build_id = malloc(BUILD_ID_SIZE);
if (build_id == NULL)
goto out_elf_end;
raw = build_id_data->d_buf + 16;
bid = build_id;
for (i = 0; i < 20; ++i) {
sprintf(bid, "%02x", *raw);
++raw;
bid += 2;
}
if (verbose)
printf("%s(%s): %s\n", __func__, self->name, build_id);
out_elf_end:
elf_end(elf);
out_close:
close(fd);
out:
return build_id;
}
int dso__load(struct dso *self, symbol_filter_t filter, int verbose)
{
int size = strlen(self->name) + sizeof("/usr/lib/debug%s.debug");
char *name = malloc(size);
int size = PATH_MAX;
char *name = malloc(size), *build_id = NULL;
int variant = 0;
int ret = -1;
int fd;
@ -686,7 +745,18 @@ int dso__load(struct dso *self, symbol_filter_t filter, int verbose)
case 1: /* Ubuntu */
snprintf(name, size, "/usr/lib/debug%s", self->name);
break;
case 2: /* Sane people */
case 2:
build_id = dso__read_build_id(self, verbose);
if (build_id != NULL) {
snprintf(name, size,
"/usr/lib/debug/.build-id/%.2s/%s.debug",
build_id, build_id + 2);
free(build_id);
break;
}
variant++;
/* Fall thru */
case 3: /* Sane people */
snprintf(name, size, "%s", self->name);
break;