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Commit fd7a346e authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo Committed by Ingo Molnar
Browse files

perf symbols: Filename__read_build_id should look at .notes section too 



In the kernel we have more than one notes section, so the linker
script combines all and puts them into a ".notes" combined
section. So we need to look at both sections and also traverse
them looking at multiple GElf_Nhdr entries till we find the one
we want, with the build_id.

Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1258757489-5978-2-git-send-email-acme@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6671cb16

tools/perf/util/symbol.c

+38 −9
Original line number Original line Diff line number Diff line
@@ -899,13 +899,19 @@ bool dsos__read_build_ids(void) 
	return have_build_id;

	return have_build_id;

}

}





/*

 * Align offset to 4 bytes as needed for note name and descriptor data.

 */

#define NOTE_ALIGN(n) (((n) + 3) & -4U)



int filename__read_build_id(const char *filename, void *bf, size_t size)

int filename__read_build_id(const char *filename, void *bf, size_t size)

{

{

	int fd, err = -1;

	int fd, err = -1;

	GElf_Ehdr ehdr;

	GElf_Ehdr ehdr;

	GElf_Shdr shdr;

	GElf_Shdr shdr;

	Elf_Data *build_id_data;

	Elf_Data *data;

	Elf_Scn *sec;

	Elf_Scn *sec;

	void *ptr;

	Elf *elf;

	Elf *elf;





	if (size < BUILD_ID_SIZE)

	if (size < BUILD_ID_SIZE)
@@ -928,14 +934,37 @@ int filename__read_build_id(const char *filename, void *bf, size_t size) 




	sec = elf_section_by_name(elf, &ehdr, &shdr,

	sec = elf_section_by_name(elf, &ehdr, &shdr,

				  ".note.gnu.build-id", NULL);

				  ".note.gnu.build-id", NULL);

	if (sec == NULL) {

		sec = elf_section_by_name(elf, &ehdr, &shdr,

					  ".notes", NULL);

		if (sec == NULL)

		if (sec == NULL)

			goto out_elf_end;

			goto out_elf_end;

	}





	build_id_data = elf_getdata(sec, NULL);

	data = elf_getdata(sec, NULL);

	if (build_id_data == NULL)

	if (data == NULL)

		goto out_elf_end;

		goto out_elf_end;

	memcpy(bf, build_id_data->d_buf + 16, BUILD_ID_SIZE);



	ptr = data->d_buf;

	while (ptr < (data->d_buf + data->d_size)) {

		GElf_Nhdr *nhdr = ptr;

		int namesz = NOTE_ALIGN(nhdr->n_namesz),

		    descsz = NOTE_ALIGN(nhdr->n_descsz);

		const char *name;



		ptr += sizeof(*nhdr);

		name = ptr;

		ptr += namesz;

		if (nhdr->n_type == NT_GNU_BUILD_ID &&

		    nhdr->n_namesz == sizeof("GNU")) {

			if (memcmp(name, "GNU", sizeof("GNU")) == 0) {

				memcpy(bf, ptr, BUILD_ID_SIZE);

				err = BUILD_ID_SIZE;

				err = BUILD_ID_SIZE;

				break;

			}

		}

		ptr += descsz;

	}

out_elf_end:

out_elf_end:

	elf_end(elf);

	elf_end(elf);

out_close:

out_close:
@@ -963,8 +992,8 @@ int sysfs__read_build_id(const char *filename, void *build_id, size_t size) 
		if (read(fd, &nhdr, sizeof(nhdr)) != sizeof(nhdr))

		if (read(fd, &nhdr, sizeof(nhdr)) != sizeof(nhdr))

			break;

			break;





		namesz = (nhdr.n_namesz + 3) & -4U;

		namesz = NOTE_ALIGN(nhdr.n_namesz);

		descsz = (nhdr.n_descsz + 3) & -4U;

		descsz = NOTE_ALIGN(nhdr.n_descsz);

		if (nhdr.n_type == NT_GNU_BUILD_ID &&

		if (nhdr.n_type == NT_GNU_BUILD_ID &&

		    nhdr.n_namesz == sizeof("GNU")) {

		    nhdr.n_namesz == sizeof("GNU")) {

			if (read(fd, bf, namesz) != namesz)

			if (read(fd, bf, namesz) != namesz)