linux-kernel - Re: [PATCH 06/25] perf tools: Do not swap mmap2 fields in case it contains build id

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Message-ID: <20201126173042.GF53384@kernel.org>
Date:   Thu, 26 Nov 2020 14:30:42 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Song Liu <songliubraving@...com>,
        Ian Rogers <irogers@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 06/25] perf tools: Do not swap mmap2 fields in case it
 contains build id

Em Thu, Nov 26, 2020 at 06:00:07PM +0100, Jiri Olsa escreveu:
> If PERF_RECORD_MISC_MMAP_BUILD_ID misc bit is set,
> mmap2 event carries build id, placed in following union:
> 
>   union {
>           struct {
>                   u32       maj;
>                   u32       min;
>                   u64       ino;
>                   u64       ino_generation;
>           };
>           struct {
>                   u8        build_id[20];
>                   u8        build_id_size;
>                   u8        __reserved_1;
>                   u16       __reserved_2;
>           };
>   };

Did you forgot to update just this cset comment?

- Arnaldo
 
> In this case we can't swap above fields.
> 
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/perf/util/session.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 5cc722b6fe7c..cc1c11ca94fd 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -592,10 +592,13 @@ static void perf_event__mmap2_swap(union perf_event *event,
>  	event->mmap2.start = bswap_64(event->mmap2.start);
>  	event->mmap2.len   = bswap_64(event->mmap2.len);
>  	event->mmap2.pgoff = bswap_64(event->mmap2.pgoff);
> -	event->mmap2.maj   = bswap_32(event->mmap2.maj);
> -	event->mmap2.min   = bswap_32(event->mmap2.min);
> -	event->mmap2.ino   = bswap_64(event->mmap2.ino);
> -	event->mmap2.ino_generation = bswap_64(event->mmap2.ino_generation);
> +
> +	if (!(event->header.misc & PERF_RECORD_MISC_MMAP_BUILD_ID)) {
> +		event->mmap2.maj   = bswap_32(event->mmap2.maj);
> +		event->mmap2.min   = bswap_32(event->mmap2.min);
> +		event->mmap2.ino   = bswap_64(event->mmap2.ino);
> +		event->mmap2.ino_generation = bswap_64(event->mmap2.ino_generation);
> +	}
>  
>  	if (sample_id_all) {
>  		void *data = &event->mmap2.filename;
> -- 
> 2.26.2
> 

-- 

- Arnaldo