[PATCH 5.4 237/389] perf symbol: Fail to read phdr workaround

Greg Kroah-Hartman
2022-08-23T11:42:12Z

From: Ian Rogers <irogers@google.com>

[ 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: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Leo 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: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/symbol-elf.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 0b185b1090ff..a04a7dfb8ec0 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -1159,16 +1159,29 @@ 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;
}
- 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);
--
2.35.1