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| author | Namhyung Kim <namhyung@kernel.org> | 2021-09-11 01:46:30 +0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2021-09-11 22:04:47 +0300 |
| commit | 4a86d41404005a3c7e7b6065e8169ac6202887a9 (patch) | |
| tree | 47fc804d4d98b6335651c8c611f41333733633d3 /tools | |
| parent | 99fc5941b835d662eb2e91d8b61249e9a51df9f0 (diff) | |
| download | linux-4a86d41404005a3c7e7b6065e8169ac6202887a9.tar.xz | |
perf tools: Allow build-id with trailing zeros
Currently perf saves a build-id with size but old versions assumes the
size of 20. In case the build-id is less than 20 (like for MD5), it'd
fill the rest with 0s.
I saw a problem when old version of perf record saved a binary in the
build-id cache and new version of perf reads the data. The symbols
should be read from the build-id cache (as the path no longer has the
same binary) but it failed due to mismatch in the build-id.
symsrc__init: build id mismatch for /home/namhyung/.debug/.build-id/53/e4c2f42a4c61a2d632d92a72afa08f00000000/elf.
The build-id event in the data has 20 byte build-ids, but it saw a
different size (16) when it reads the build-id of the elf file in the
build-id cache.
$ readelf -n ~/.debug/.build-id/53/e4c2f42a4c61a2d632d92a72afa08f00000000/elf
Displaying notes found in: .note.gnu.build-id
Owner Data size Description
GNU 0x00000010 NT_GNU_BUILD_ID (unique build ID bitstring)
Build ID: 53e4c2f42a4c61a2d632d92a72afa08f
Let's fix this by allowing trailing zeros if the size is different.
Fixes: 39be8d0115b321ed ("perf tools: Pass build_id object to dso__build_id_equal()")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210910224630.1084877-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/perf/util/dso.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c index ee15db2be2f4..9ed9a5676d35 100644 --- a/tools/perf/util/dso.c +++ b/tools/perf/util/dso.c @@ -1349,6 +1349,16 @@ void dso__set_build_id(struct dso *dso, struct build_id *bid) bool dso__build_id_equal(const struct dso *dso, struct build_id *bid) { + if (dso->bid.size > bid->size && dso->bid.size == BUILD_ID_SIZE) { + /* + * For the backward compatibility, it allows a build-id has + * trailing zeros. + */ + return !memcmp(dso->bid.data, bid->data, bid->size) && + !memchr_inv(&dso->bid.data[bid->size], 0, + dso->bid.size - bid->size); + } + return dso->bid.size == bid->size && memcmp(dso->bid.data, bid->data, dso->bid.size) == 0; } |