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authorLeo Yan <leo.yan@linaro.org>2022-07-24 14:00:13 +0800
committerArnaldo Carvalho de Melo <acme@redhat.com>2022-07-27 11:17:50 -0300
commit882528d2e77687c3ef26abb9c490f77a9c1f6e1a (patch)
tree6b02b93266429559cb90d58b922268cf192f831b /tools/perf
parent2d86612aacb7805f72873691a2644d7279ed0630 (diff)
perf symbol: Skip symbols if SHF_ALLOC flag is not set
Some symbols are observed with the 'st_value' field zeroed. E.g. libc.so.6 in Ubuntu contains a symbol '__evoke_link_warning_getwd' which resides in the '.gnu.warning.getwd' section. Unlike normal sections, such kind of sections are used for linker warning when a file calls deprecated functions, but they are not part of memory images, the symbols in these sections should be dropped. This patch checks the section attribute SHF_ALLOC bit, if the bit is not set, it skips symbols to avoid spurious ones. Suggested-by: Fangrui Song <maskray@google.com> Signed-off-by: Leo Yan <leo.yan@linaro.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Chang Rui <changruinj@gmail.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20220724060013.171050-3-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
-rw-r--r--tools/perf/util/symbol-elf.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index ef6ced5c5746..b3be5b1d9dbb 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -1255,6 +1255,17 @@ dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
gelf_getshdr(sec, &shdr);
+ /*
+ * If the attribute bit SHF_ALLOC is not set, the section
+ * doesn't occupy memory during process execution.
+ * E.g. ".gnu.warning.*" section is used by linker to generate
+ * warnings when calling deprecated functions, the symbols in
+ * the section aren't loaded to memory during process execution,
+ * so skip them.
+ */
+ if (!(shdr.sh_flags & SHF_ALLOC))
+ continue;
+
secstrs = secstrs_sym;
/*