From: Ajay Kaher akaher@vmware.com
[ Upstream commit 6f520ce17920b3cdfbd2479b3ccf27f9706219d0 ]
perf doesn't provide proper symbol information for specially crafted .debug files.
Sometimes .debug file may not have similar program header as runtime ELF file. For example if we generate .debug file using objcopy --only-keep-debug resulting file will not contain .text, .data and other runtime sections. That means corresponding program headers will have zero FileSiz and modified Offset.
Example: program header of text section of libxxx.so:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flags Align LOAD 0x00000000003d3000 0x00000000003d3000 0x00000000003d3000 0x000000000055ae80 0x000000000055ae80 R E 0x1000
Same program header after executing: objcopy --only-keep-debug libxxx.so libxxx.so.debug
LOAD 0x0000000000001000 0x00000000003d3000 0x00000000003d3000 0x0000000000000000 0x000000000055ae80 R E 0x1000
Offset and FileSiz have been changed.
Following formula will not provide correct value, if program header taken from .debug file (syms_ss):
sym.st_value -= phdr.p_vaddr - phdr.p_offset;
Correct program header information is located inside runtime ELF file (runtime_ss).
Fixes: 2d86612aacb7805f ("perf symbol: Correct address for bss symbols") Signed-off-by: Ajay Kaher akaher@vmware.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Alexey Makhalov amakhalov@vmware.com Cc: Jiri Olsa jolsa@kernel.org Cc: Leo Yan leo.yan@linaro.org Cc: Mark Rutland mark.rutland@arm.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Cc: Srivatsa S. Bhat srivatsab@vmware.com Cc: Steven Rostedt (VMware) rostedt@goodmis.org Cc: Vasavi Sirnapalli vsirnapalli@vmware.com Link: http://lore.kernel.org/lkml/1669198696-50547-1-git-send-email-akaher@vmware.... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/symbol-elf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 3e423a920015..5221f272f85c 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -1247,7 +1247,7 @@ int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss, (!used_opd && syms_ss->adjust_symbols)) { GElf_Phdr phdr;
- if (elf_read_program_header(syms_ss->elf, + if (elf_read_program_header(runtime_ss->elf, (u64)sym.st_value, &phdr)) { pr_debug4("%s: failed to find program header for " "symbol: %s st_value: %#" PRIx64 "\n",