Hi,
We are seeing an issue with doing Coresight decode off target where initially the correct dso from ~/.debug is used, but after a new thread in the perf.data file is passed with its mmap record, the local version of the dso is picked up instead. This happens if the binary exists in the same path on both devices, for example /bin/ls.
Initially when parsing the build-ids in the header, the dso for /bin/ls will be created, and the file will correctly point to ~/.debug/bin/ls/2f15ad836be3339dec0e2e6a3c637e08e48aacbd/elf, but for any new threads or mmaps that are also for /bin/ls, they will not have a build-id set so they point to /bin/ls on the local machine rather than the debug folder.
To fix this I made it possible to look up which existing dsos have build id's set that originate from the header and then copy that build-id onto the new dso if the name matches. Another way to do it would be to stop comparing the mmap id so it matches on filename only, but I think we do want to differentiate between different mmaps, even if they have the same name, which is how it works in this version.
Applies to perf/core 859f7e4554
Thanks James
James Clark (1): perf: Set build-id using build-id header on new mmap records
tools/perf/util/dso.h | 1 + tools/perf/util/header.c | 1 + tools/perf/util/map.c | 16 ++++++++++++++-- 3 files changed, 16 insertions(+), 2 deletions(-)
MMAP records that occur after the build-id header is parsed do not have their build-id set even if the filename matches an entry from the header. Set the build-id on these dsos as long as the MMAP record doesn't have its own build-id set.
This fixes an issue with off target analysis where the local version of a dso is loaded rather than one from ~/.debug via a build-id.
Reported-by: Denis Nikitin denik@chromium.org Signed-off-by: James Clark james.clark@arm.com --- tools/perf/util/dso.h | 1 + tools/perf/util/header.c | 1 + tools/perf/util/map.c | 16 ++++++++++++++-- 3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h index 011da3924fc1..3a9fd4d389b5 100644 --- a/tools/perf/util/dso.h +++ b/tools/perf/util/dso.h @@ -167,6 +167,7 @@ struct dso { enum dso_load_errno load_errno; u8 adjust_symbols:1; u8 has_build_id:1; + u8 header_build_id:1; u8 has_srcline:1; u8 hit:1; u8 annotate_warned:1; diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 6da12e522edc..571d73d4f976 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -2200,6 +2200,7 @@ static int __event_process_build_id(struct perf_record_header_build_id *bev,
build_id__init(&bid, bev->data, size); dso__set_build_id(dso, &bid); + dso->header_build_id = 1;
if (dso_space != DSO_SPACE__USER) { struct kmod_path m = { .name = NULL, }; diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c index 1803d3887afe..4ae91e491e23 100644 --- a/tools/perf/util/map.c +++ b/tools/perf/util/map.c @@ -127,7 +127,7 @@ struct map *map__new(struct machine *machine, u64 start, u64 len,
if (map != NULL) { char newfilename[PATH_MAX]; - struct dso *dso; + struct dso *dso, *header_bid_dso; int anon, no_dso, vdso, android;
android = is_android_lib(filename); @@ -185,7 +185,19 @@ struct map *map__new(struct machine *machine, u64 start, u64 len,
if (build_id__is_defined(bid)) dso__set_build_id(dso, bid); - + else { + /* + * If the mmap event had no build ID, search for an existing dso from the + * build ID header by name. Otherwise only the dso loaded at the time of + * reading the header will have the build ID set and all future mmaps will + * have it missing. + */ + header_bid_dso = __dsos__find(&machine->dsos, filename, false); + if (header_bid_dso && header_bid_dso->header_build_id) { + dso__set_build_id(dso, &header_bid_dso->bid); + dso->header_build_id = 1; + } + } dso__put(dso); } return map;
-
James Clark