diff options
| author | Namhyung Kim <namhyung@kernel.org> | 2024-11-27 17:03:25 -0800 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2024-12-12 15:36:46 -0300 |
| commit | ad5d76aecdcfe73a4093a9755a991f172d2d2492 (patch) | |
| tree | 07337b263e7a27a0879f9705d797696750b30a0b | |
| parent | b1ef2559d5579b1bc34f062aef53e9c1e52c91b0 (diff) | |
perf tools: Avoid unaligned pointer operations
The sample data is 64-bit aligned basically but raw data starts with
32-bit length field and data follows. In perf_event__synthesize_sample
it treats the sample data as a 64-bit array. And it needs some trick
to update the raw data properly.
But it seems some compilers are not happy with this and the program dies
siliently. I found the sample parsing test failed without any messages
on affected systems.
Let's update the code to use a 32-bit pointer directly and make sure the
result is 64-bit aligned again. No functional changes intended.
Reviewed-by: Ian Rogers <irogers@google.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241128010325.946897-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
| -rw-r--r-- | tools/perf/util/synthetic-events.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index a58444c4aed1..6923b0d5efed 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -1686,12 +1686,16 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo } if (type & PERF_SAMPLE_RAW) { - u.val32[0] = sample->raw_size; - *array = u.val64; - array = (void *)array + sizeof(u32); + u32 *array32 = (void *)array; + + *array32 = sample->raw_size; + array32++; + + memcpy(array32, sample->raw_data, sample->raw_size); + array = (void *)(array32 + (sample->raw_size / sizeof(u32))); - memcpy(array, sample->raw_data, sample->raw_size); - array = (void *)array + sample->raw_size; + /* make sure the array is 64-bit aligned */ + BUG_ON(((long)array) % sizeof(u64)); } if (type & PERF_SAMPLE_BRANCH_STACK) { |