| Message ID | 1453986324-31105-1-git-send-email-wangnan0@huawei.com |
|---|---|
| State | Superseded |
| Headers | show |
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 562b8eb..d37e206 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -712,6 +712,7 @@ 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 || + ehdr.e_type == ET_DYN || dso__is_vdso(dso) || elf_section_by_name(elf, &ehdr, &shdr, ".gnu.prelink_undo",
He Kuang reported a problem that perf fails to get correct symbol on Android platform in [1]. The problem can be reproduced on normal x86_64 platform. I will describe the reproducing steps in detail at the end of commit message. The reason of this problem is missing of symbol adjustment for normal shared objects. In most of the cases it works correctly, but when '.text' section having differeng 'address' and 'offset' the result is wrong. I checked all shared objects in my working platform, only wine dll objects and debug objects (in .debug) have this problem. However, it is common on Android. For example: $ readelf -S ./libsurfaceflinger.so | grep \.text [10] .text PROGBITS 0000000000029030 00012030 This patch enables symbol adjustment for dynamic objects so the symbol address got from elfutils would be adjusted correctly. Steps to reproduce the problem: $ cat << EOF > ./Makefile PWD := $(shell pwd) LDFLAGS += "-Wl,-rpath=$(PWD)" CFLAGS += -g main: main.c libbuggy.so libbuggy.so: buggy.c gcc -g -shared -fPIC -Wl,-Ttext-segment=0x200000 $< -o $@ clean: rm -rf main libbuggy.so *.o EOF $ cat << EOF > ./buggy.c int fib(int x) { return (x == 0) ? 1 : (x == 1) ? 1 : fib(x - 1) + fib(x - 2); } EOF $ cat << EOF > ./main.c #include <stdio.h> extern int fix(int x); int main() { int i; for (i = 0; i < 40; i++) printf("%d\n", fib(i)); return 0; } EOF $ make $ perf record ./main ... $ perf report --stdio # Overhead Command Shared Object Symbol # ........ ....... ................. ............................... # 14.97% main libbuggy.so [.] 0x000000000000066c 8.68% main libbuggy.so [.] 0x00000000000006aa 8.52% main libbuggy.so [.] fib@plt 7.95% main libbuggy.so [.] 0x0000000000000664 5.94% main libbuggy.so [.] 0x00000000000006a9 5.35% main libbuggy.so [.] 0x0000000000000678 ... The correct result should be (after this patch): # Overhead Command Shared Object Symbol # ........ ....... ................. ............................... # 91.47% main libbuggy.so [.] fib 8.52% main libbuggy.so [.] fib@plt 0.00% main [kernel.kallsyms] [k] kmem_cache_free [1] http://lkml.kernel.org/g/1452567507-54013-1-git-send-email-hekuang@huawei.com Signed-off-by: Wang Nan <wangnan0@huawei.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: He Kuang <hekuang@huawei.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: pi3orama@163.com --- tools/perf/util/symbol-elf.c | 1 + 1 file changed, 1 insertion(+) -- 1.8.3.4