linux-kernel - Re: [PATCH 03/24] perf: Add build id data in mmap2 event

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Message-ID: <20201117111334.GL3121392@hirez.programming.kicks-ass.net>
Date:   Tue, 17 Nov 2020 12:13:34 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        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 03/24] perf: Add build id data in mmap2 event

On Tue, Nov 17, 2020 at 12:00:32PM +0100, Jiri Olsa wrote:
> Adding support to carry build id data in mmap2 event.
> 
> The build id data replaces maj/min/ino/ino_generation
> fields, which are also used to identify map's binary,
> so it's ok to replace them with build id data:
> 
>   union {
>           struct {
>                   u32       maj;
>                   u32       min;
>                   u64       ino;
>                   u64       ino_generation;
>           };
>           struct {
>                   u8        build_id_size;
>                   u8        __reserved_1;
>                   u16       __reserved_2;
>                   u8        build_id[20];
>           };
>   };
> 
> Replaced maj/min/ino/ino_generation fields give us size
> of 24 bytes. We use 20 bytes for build id data, 1 byte
> for size and rest is unused.
> 
> There's new misc bit for mmap2 to signal there's build
> id data in it:
> 
>   #define PERF_RECORD_MISC_MMAP_BUILD_ID   (1 << 14)
> 
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>

Seems sane enough; how do we want to route this?

Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>