[PATCH v2 1/2] perf tools: Honor namespace when synthesizing build-id

[Namhyung Kim]

It needs to go into a namespace before reading a file.

Fixes: 4183a8d70a28 ("perf tools: Allow synthesizing the build id for kernel/modules/tasks in PERF_RECORD_MMAP2")
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/util/synthetic-events.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 0ff57ca24577..289ea17ac5f7 100644
--- 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;
-- 
2.37.3.968.ga6b4b080e4-goog