Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753514AbbF0JKo (ORCPT ); Sat, 27 Jun 2015 05:10:44 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:49705 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753167AbbF0JKe (ORCPT ); Sat, 27 Jun 2015 05:10:34 -0400 From: Will Deacon To: acme@redhat.com Cc: linux-kernel@vger.kernel.org, kristina.martsenko@arm.com, Will Deacon , Vladimir Nikulichev , Adrian Hunter , Namhyung Kim , Andy Lutomirski Subject: [PATCH v2] perf tools: don't adjust symbols in vDSO Date: Sat, 27 Jun 2015 10:10:13 +0100 Message-Id: <1435396213-30208-1-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2935 Lines: 82 Commit 922d0e4d9f04 ("perf tools: Adjust symbols in VDSO") changed the ELF symbol parsing so that the vDSO is treated the same as ET_EXEC and ET_REL binaries despite being an ET_DYN. This was a partial workaround to deal with older x86 vDSOs being prelinked at a high address that didn't correspond to the map, so using object-relative offsets and adding the base of the map allowed symbol resolution to succeed. Unfortunately, this causes objdump not to produce any output in conjunction with perf annotate, which cheerfully passes the absolute address of the map symbol. This patch fixes the problem by avoiding adjustment of vDSO symbols and instead setting the map->pgoff field to correspond to the virtual load address specified in the vDSO ELF header. Cc: Vladimir Nikulichev Cc: Adrian Hunter Cc: Namhyung Kim Cc: Andy Lutomirski Reported-by: Kristina Martsenko Signed-off-by: Will Deacon --- v1->v2: Adjust map->pgoff in ELF loader to avoid breaking symbol lookup on older kernels. tools/perf/util/map.c | 5 ++--- tools/perf/util/symbol-elf.c | 9 ++++++++- 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c index a14f08f41686..6ba38293be88 100644 --- a/tools/perf/util/map.c +++ b/tools/perf/util/map.c @@ -173,10 +173,9 @@ struct map *map__new(struct machine *machine, u64 start, u64 len, filename = newfilename; } - if (vdso) { - pgoff = 0; + if (vdso) dso = vdso__dso_findnew(machine, thread); - } else + else dso = __dsos__findnew(&machine->user_dsos, filename); if (dso == NULL) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index a7ab6063e038..83f8ba232575 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -706,7 +706,6 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, GElf_Shdr shdr; ss->adjust_symbols = (ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL || - dso__is_vdso(dso) || elf_section_by_name(elf, &ehdr, &shdr, ".gnu.prelink_undo", NULL) != NULL); @@ -824,6 +823,14 @@ int dso__load_sym(struct dso *dso, struct map *map, sec = syms_ss->symtab; shdr = syms_ss->symshdr; + /* + * Older x86 kernels prelink the vDSO at a high address, so + * we need to reflect that in map->pgoff in order to talk to + * objdump. + */ + if (dso__is_vdso(dso)) + map->pgoff = shdr.sh_addr - shdr.sh_offset; + if (runtime_ss->opdsec) opddata = elf_rawdata(runtime_ss->opdsec, NULL); -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/