Re: [PATCH 8/9] perf tools: Add size to struct perf_record_header_build_id

From: Ian Rogers
Date: Thu Oct 01 2020 - 01:32:02 EST


On Wed, Sep 30, 2020 at 10:15 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> We do not store size with build ids in perf data,
> but there's enough space to do it. Adding misc bit
> PERF_RECORD_MISC_BUILD_ID_SIZE to mark build id event
> with size.
>
> With this fix the dso with md5 build id will have correct
> build id data and will be usable for debuginfod processing
> if needed (coming in following patches).
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>

Acked-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
> tools/lib/perf/include/perf/event.h | 12 +++++++++++-
> tools/perf/util/build-id.c | 8 +++++---
> tools/perf/util/header.c | 10 +++++++---
> 3 files changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h
> index a6dbba6b9073..988c539bedb6 100644
> --- a/tools/lib/perf/include/perf/event.h
> +++ b/tools/lib/perf/include/perf/event.h
> @@ -201,10 +201,20 @@ struct perf_record_header_tracing_data {
> __u32 size;
> };
>
> +#define PERF_RECORD_MISC_BUILD_ID_SIZE (1 << 15)
> +
> struct perf_record_header_build_id {
> struct perf_event_header header;
> pid_t pid;
> - __u8 build_id[24];
> + union {
> + __u8 build_id[24];
> + struct {
> + __u8 data[20];
> + __u8 size;
> + __u8 reserved1__;
> + __u16 reserved2__;
> + };
> + };
> char filename[];
> };
>
> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> index b5648735f01f..8763772f1095 100644
> --- a/tools/perf/util/build-id.c
> +++ b/tools/perf/util/build-id.c
> @@ -296,7 +296,7 @@ char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
> continue; \
> else
>
> -static int write_buildid(const char *name, size_t name_len, u8 *build_id,
> +static int write_buildid(const char *name, size_t name_len, struct build_id *bid,
> pid_t pid, u16 misc, struct feat_fd *fd)
> {
> int err;
> @@ -307,7 +307,9 @@ static int write_buildid(const char *name, size_t name_len, u8 *build_id,
> len = PERF_ALIGN(len, NAME_ALIGN);
>
> memset(&b, 0, sizeof(b));
> - memcpy(&b.build_id, build_id, BUILD_ID_SIZE);
> + memcpy(&b.data, bid->data, bid->size);
> + b.size = (u8) bid->size;
> + misc |= PERF_RECORD_MISC_BUILD_ID_SIZE;
> b.pid = pid;
> b.header.misc = misc;
> b.header.size = sizeof(b) + len;
> @@ -354,7 +356,7 @@ static int machine__write_buildid_table(struct machine *machine,
> in_kernel = pos->kernel ||
> is_kernel_module(name,
> PERF_RECORD_MISC_CPUMODE_UNKNOWN);
> - err = write_buildid(name, name_len, pos->bid.data, machine->pid,
> + err = write_buildid(name, name_len, &pos->bid, machine->pid,
> in_kernel ? kmisc : umisc, fd);
> if (err)
> break;
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 21243adbb9fd..8da3886f10a8 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -2083,8 +2083,12 @@ static int __event_process_build_id(struct perf_record_header_build_id *bev,
> if (dso != NULL) {
> char sbuild_id[SBUILD_ID_SIZE];
> struct build_id bid;
> + size_t size = BUILD_ID_SIZE;
>
> - build_id__init(&bid, bev->build_id, BUILD_ID_SIZE);
> + if (bev->header.misc & PERF_RECORD_MISC_BUILD_ID_SIZE)
> + size = bev->size;
> +
> + build_id__init(&bid, bev->data, size);
> dso__set_build_id(dso, &bid);
>
> if (dso_space != DSO_SPACE__USER) {
> @@ -2098,8 +2102,8 @@ static int __event_process_build_id(struct perf_record_header_build_id *bev,
> }
>
> build_id__sprintf(&dso->bid, sbuild_id);
> - pr_debug("build id event received for %s: %s\n",
> - dso->long_name, sbuild_id);
> + pr_debug("build id event received for %s: %s [%lu]\n",
> + dso->long_name, sbuild_id, size);
> dso__put(dso);
> }
>
> --
> 2.26.2
>