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Subject[PATCH 1/1] perf symbols: ignore mapping symbols on ARM
Date
Applies to linux-2.6-tip/master or acme/perf-core

ARM ELF files use symbols with special names $a, $t, $d to
identify regions of ARM code, Thumb code and data within code
sections. This can cause confusing output from the perf tools,
especially for partially stripped binaries, or binaries
containing user-added zero-sized symbols (which may occur in
hand-written assembler which hasn't been fully annotated with
.size directives).

This patch filters out these symbols at load time.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
---
tools/perf/util/symbol.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b6f5970..1a36773 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1079,6 +1079,16 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
if (!is_label && !elf_sym__is_a(&sym, map->type))
continue;

+ /* Reject ARM ELF "mapping symbols": these aren't unique and
+ * don't identify functions, so will confuse the profile
+ * output: */
+ if (ehdr.e_machine == EM_ARM) {
+ if (!strcmp(elf_name, "$a") ||
+ !strcmp(elf_name, "$d") ||
+ !strcmp(elf_name, "$t"))
+ continue;
+ }
+
if (opdsec && sym.st_shndx == opdidx) {
u32 offset = sym.st_value - opdshdr.sh_addr;
u64 *opd = opddata->d_buf + offset;
--
1.7.0.4


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