linux-kernel - [PATCH] perf inject: Keep build-ID data if no option is used

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Message-ID: <20251217183927.2259237-1-namhyung@kernel.org>
Date: Wed, 17 Dec 2025 10:39:27 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	James Clark <james.clark@...aro.org>
Cc: Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org,
	Gabriel Marin <gmx@...gle.com>
Subject: [PATCH] perf inject: Keep build-ID data if no option is used

The keep_feat() determines which header features will be kept or
discarded.  Usually perf inject will add build-IDs based on -b, -B or
other related options.  But it lose build-ID when none of those options
are used.  This is meaningful only when --buildid-mmap is not used.

The following example shows the impact of this change.

  $ perf record --no-buildid-mmap true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.037 MB perf.data (5 samples) ]

  $ perf inject -i perf.data -o perf.data.inject

  $ perf buildid-list -i perf.data
  08cccc2a9388d5247ccb3e864f3063b975b0a15d /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
  fd5c4d5673256cd6bda51725dba048dabb0f854e [kernel.kallsyms]
  97a36ce1140071be5c36b147fa0bed173e05a602 [vdso]

  $ perf buildid-list -i perf.data.inject
  97a36ce1140071be5c36b147fa0bed173e05a602 [vdso]

With this change, perf.data.inject would show the same list (of course,
you need to run perf inject again).

Reported-by: Gabriel Marin <gmx@...gle.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/builtin-inject.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index aa7be4fb5838fb99..6080afec537d2178 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -2022,7 +2022,7 @@ static int save_section_info(struct perf_inject *inject)
 	return perf_header__process_sections(header, fd, inject, save_section_info_cb);
 }
 
-static bool keep_feat(int feat)
+static bool keep_feat(struct perf_inject *inject, int feat)
 {
 	switch (feat) {
 	/* Keep original information that describes the machine or software */
@@ -2050,6 +2050,7 @@ static bool keep_feat(int feat)
 		return true;
 	/* Information that can be updated */
 	case HEADER_BUILD_ID:
+		return inject->build_id_style == BID_RWS__NONE;
 	case HEADER_CMDLINE:
 	case HEADER_EVENT_DESC:
 	case HEADER_BRANCH_STACK:
@@ -2108,7 +2109,7 @@ static int feat_copy_cb(struct feat_copier *fc, int feat, struct feat_writer *fw
 	int ret;
 
 	if (!inject->secs[feat].offset ||
-	    !keep_feat(feat))
+	    !keep_feat(inject, feat))
 		return 0;
 
 	ret = feat_copy(inject, feat, fw);
-- 
2.52.0.313.g674ac2bdf7-goog