From fd7a346ea292074e9f6cdb5232a57c56bf98fdc9 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Fri, 20 Nov 2009 20:51:25 -0200 Subject: [PATCH] perf symbols: Filename__read_build_id should look at .notes section too MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: Arnaldo Carvalho de Melo Cc: Frédéric Weisbecker Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Paul Mackerras LKML-Reference: <1258757489-5978-2-git-send-email-acme@infradead.org> Signed-off-by: Ingo Molnar --- tools/perf/util/symbol.c | 47 ++++++++++++++++++++++++++++++++-------- 1 file changed, 38 insertions(+), 9 deletions(-) diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 3b23c18cd36..d22030828c2 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -899,13 +899,19 @@ bool dsos__read_build_ids(void) 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 fd, err = -1; GElf_Ehdr ehdr; GElf_Shdr shdr; - Elf_Data *build_id_data; + Elf_Data *data; Elf_Scn *sec; + void *ptr; Elf *elf; 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, ".note.gnu.build-id", NULL); - if (sec == NULL) - goto out_elf_end; + if (sec == NULL) { + sec = elf_section_by_name(elf, &ehdr, &shdr, + ".notes", NULL); + if (sec == NULL) + goto out_elf_end; + } - build_id_data = elf_getdata(sec, NULL); - if (build_id_data == NULL) + data = elf_getdata(sec, NULL); + if (data == NULL) goto out_elf_end; - memcpy(bf, build_id_data->d_buf + 16, BUILD_ID_SIZE); - err = 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; + break; + } + } + ptr += descsz; + } out_elf_end: elf_end(elf); 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)) break; - namesz = (nhdr.n_namesz + 3) & -4U; - descsz = (nhdr.n_descsz + 3) & -4U; + namesz = NOTE_ALIGN(nhdr.n_namesz); + descsz = NOTE_ALIGN(nhdr.n_descsz); if (nhdr.n_type == NT_GNU_BUILD_ID && nhdr.n_namesz == sizeof("GNU")) { if (read(fd, bf, namesz) != namesz) -- 2.41.0