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

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

[Namhyung Kim]

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@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.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

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

[Ian Rogers]

On Wed, Dec 17, 2025 at 10:39 AM Namhyung Kim <namhyung@kernel.org> wrote:
>
> 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@google.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
>  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
>

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

[Namhyung Kim]

Hi Ian,

On Wed, Dec 17, 2025 at 10:57:01AM -0800, Ian Rogers wrote:
> On Wed, Dec 17, 2025 at 10:39 AM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > 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@google.com>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> 
> Reviewed-by: Ian Rogers <irogers@google.com>

Thanks for the review!

Arnaldo, any chance you can pick this up soon?

Thanks,
Namhyung

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

[Arnaldo Carvalho de Melo]

On Thu, Jan 08, 2026 at 03:57:28PM -0800, Namhyung Kim wrote:
> Hi Ian,
> 
> On Wed, Dec 17, 2025 at 10:57:01AM -0800, Ian Rogers wrote:
> > On Wed, Dec 17, 2025 at 10:39 AM Namhyung Kim <namhyung@kernel.org> wrote:
> > >
> > > 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@google.com>
> > > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > 
> > Reviewed-by: Ian Rogers <irogers@google.com>
> 
> Thanks for the review!
> 
> Arnaldo, any chance you can pick this up soon?

Thanks, applied to perf-tools-next,

- Arnaldo