perf tools: Honor namespace when synthesizing build-ids

It needs to enter the namespace before reading a file.

Fixes: 4183a8d70a288627 ("perf tools: Allow synthesizing the build id for kernel/modules/tasks in PERF_RECORD_MMAP2")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20220920222822.2171056-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 812424dbf2d5b95f1b19df7f704f37643a87dbd6..538790758e242cf16c877356cd7351a951f1e13b 100644 (file)
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -367,13 +367,24 @@ static void perf_record_mmap2__read_build_id(struct perf_record_mmap2 *event,
                                             bool is_kernel)
 {
        struct build_id bid;
+       struct nsinfo *nsi;
+       struct nscookie nc;
        int rc;
 
-       if (is_kernel)
+       if (is_kernel) {
                rc = sysfs__read_build_id("/sys/kernel/notes", &bid);
-       else
-               rc = filename__read_build_id(event->filename, &bid) > 0 ? 0 : -1;
+               goto out;
+       }
+
+       nsi = nsinfo__new(event->pid);
+       nsinfo__mountns_enter(nsi, &nc);
 
+       rc = filename__read_build_id(event->filename, &bid) > 0 ? 0 : -1;
+
+       nsinfo__mountns_exit(&nc);
+       nsinfo__put(nsi);
+
+out:
        if (rc == 0) {
                memcpy(event->build_id, bid.data, sizeof(bid.data));
                event->build_id_size = (u8) bid.size;