perf symbol: Fail to read phdr workaround

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 (c436ad9f4a2a0926 ("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: c436ad9f4a2a0926 ("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>

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index b3be5b1d9dbb00bcde88661bdb7e03a2505d2ca8..75bec32d4f571319e8577e96899dee2a24bb4381 100644 (file)
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -1305,16 +1305,29 @@ dso__load_sym_internal(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);