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Commit cc53477d authored by Ian Rogers's avatar Ian Rogers Committed by Greg Kroah-Hartman
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perf symbol: Fail to read phdr workaround 

[ Upstream commit 6d518ac7be6223811ab947897273b1bbef846180 ]

The perf jvmti agent doesn't create program headers, in this case
fallback on section headers as happened previously.

Committer notes:

To test this, from a public post by Ian:

1) download a Java workload dacapo-9.12-MR1-bach.jar from
https://sourceforge.net/projects/dacapobench/



2) build perf such as "make -C tools/perf O=/tmp/perf NO_LIBBFD=1" it
should detect Java and create /tmp/perf/libperf-jvmti.so

3) run perf with the jvmti agent:

  perf record -k 1 java -agentpath:/tmp/perf/libperf-jvmti.so -jar dacapo-9.12-MR1-bach.jar -n 10 fop

4) run perf inject:

  perf inject -i perf.data -o perf-injected.data -j

5) run perf report

  perf report -i perf-injected.data | grep org.apache.fop

With this patch reverted I see lots of symbols like:

     0.00%  java             jitted-388040-4656.so  [.] org.apache.fop.fo.FObj.bind(org.apache.fop.fo.PropertyList)

With the patch (2d86612aacb7805f ("perf symbol: Correct address for bss
symbols")) I see lots of:

  dso__load_sym_internal: failed to find program header for symbol:
  Lorg/apache/fop/fo/FObj;bind(Lorg/apache/fop/fo/PropertyList;)V
  st_value: 0x40

Fixes: 2d86612aacb7805f ("perf symbol: Correct address for bss symbols")
Reviewed-by: default avatarLeo Yan <leo.yan@linaro.org>
Signed-off-by: default avatarIan Rogers <irogers@google.com>
Tested-by: default avatarLeo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.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: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20220731164923.691193-1-irogers@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent f3886436

tools/perf/util/symbol-elf.c

+20 −7
Original line number Diff line number Diff line
@@ -1159,17 +1159,30 @@ int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss, 


			if (elf_read_program_header(syms_ss->elf,

						    (u64)sym.st_value, &phdr)) {

				pr_warning("%s: failed to find program header for "

				pr_debug4("%s: failed to find program header for "

					   "symbol: %s st_value: %#" PRIx64 "\n",

					   __func__, elf_name, (u64)sym.st_value);

				continue;

			}

				pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "

					"sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n",

					__func__, (u64)sym.st_value, (u64)shdr.sh_addr,

					(u64)shdr.sh_offset);

				/*

				 * Fail to find program header, let's rollback

				 * to use shdr.sh_addr and shdr.sh_offset to

				 * calibrate symbol's file address, though this

				 * is not necessary for normal C ELF file, we

				 * still need to handle java JIT symbols in this

				 * case.

				 */

				sym.st_value -= shdr.sh_addr - shdr.sh_offset;

			} else {

				pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "

					"p_vaddr: %#" PRIx64 " p_offset: %#" PRIx64 "\n",

					__func__, (u64)sym.st_value, (u64)phdr.p_vaddr,

					(u64)phdr.p_offset);

				sym.st_value -= phdr.p_vaddr - phdr.p_offset;

			}

		}



		demangled = demangle_sym(dso, kmodule, elf_name);

		if (demangled != NULL)