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Commit 4d1e00a8 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo Committed by Ingo Molnar
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perf symbol: Fix symbol parsing in certain cases: use the build-id as a symlink 



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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e0d82a0a

tools/perf/util/symbol.c

+73 −3
Original line number Diff line number Diff line
@@ -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;