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authorLexi Shao2021-10-29 14:50:37 +0800
committerArnaldo Carvalho de Melo2021-11-07 12:27:38 -0300
commit1a86f4ba5cf1c19b55a12be8e5e9235a23921f8d (patch)
tree4e8370bf59e5a84755f1830059bdab4435323928 /tools
parenteb39bf325631f9ae185abd16281079b7b9858737 (diff)
perf symbols: Ignore $a/$d symbols for ARM modules
On anARM machine, kernel symbols from modules can be resolved to $a instead of printing the actual symbol name. Ignore symbols starting with "$" when building kallsyms rbtree. A sample stacktrace is shown as follows: c0f2e39c schedule_hrtimeout+0x14 ([kernel.kallsyms]) bf4a66d8 $a+0x78 ([test_module]) c0a4f5f4 kthread+0x15c ([kernel.kallsyms]) c0a001f8 ret_from_fork+0x14 ([kernel.kallsyms]) On an ARM machine, $a/$d symbols are used by the compiler to mark the beginning of code/data part in code section. These symbols are filtered out when linking vmlinux(see scripts/kallsyms.c ignored_prefixes), but are left on modules. So there are $a symbols in /proc/kallsyms which share the same addresses with the actual module symbols and confuses perf when resolving symbols. After this patch, the module symbol name is printed: c0f2e39c schedule_hrtimeout+0x14 ([kernel.kallsyms]) bf4a66d8 test_func+0x78 ([test_module]) c0a4f5f4 kthread+0x15c ([kernel.kallsyms]) c0a001f8 ret_from_fork+0x14 ([kernel.kallsyms]) Reviewed-by: James Clark <james.clark@arm.com> Signed-off-by: Lexi Shao <shaolexi@huawei.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jessica Yu <jeyu@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: QiuXi <qiuxi1@huawei.com> Cc: Song Liu <songliubraving@fb.com> Cc: Wangbing <wangbing6@huawei.com> Cc: Xiaoming Ni <nixiaoming@huawei.com> Cc: Yonghong Song <yhs@fb.com> Cc: bpf@vger.kernel.org Cc: clang-built-linux@googlegroups.com Link: https://lore.kernel.org/r/20211029065038.39449-2-shaolexi@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/util/symbol.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 0fc9a5410739..35116aed74eb 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -702,6 +702,10 @@ static int map__process_kallsym_symbol(void *arg, const char *name,
if (!symbol_type__filter(type))
return 0;
+ /* Ignore local symbols for ARM modules */
+ if (name[0] == '$')
+ return 0;
+
/*
* module symbols are not sorted so we add all
* symbols, setting length to 0, and rely on