Subject: Re: [RFC V1 10/11] perf: Expand perf_branch_entry.type

From: Rob Herring <[email-masked]>
Date: Wed, 26 Jan 2022 10:47:59 -0600

On Mon, Jan 24, 2022 at 10:00:52AM +0530, Anshuman Khandual wrote:
> Current perf_branch_entry.type is a 4 bits field just enough to accommodate
> 16 generic branch types. This is insufficient to accommodate platforms like
> arm64 which has much more branch types. Lets just expands this field into a
> 6 bits one, which can now hold 64 generic branch types. This also adds more
> generic branch types and updates the BRBE driver as required.
> 
> Cc: Peter Zijlstra <[email-masked]>
> Cc: Ingo Molnar <[email-masked]>
> Cc: Arnaldo Carvalho de Melo <[email-masked]>
> Cc: Mark Rutland <[email-masked]>
> Cc: Alexander Shishkin <[email-masked]>
> Cc: Jiri Olsa <[email-masked]>
> Cc: Namhyung Kim <[email-masked]>
> Cc: Will Deacon <[email-masked]>
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Signed-off-by: Anshuman Khandual <[email-masked]>
> ---
>  drivers/perf/arm_pmu_brbe.c           |  7 ++++++-

This patch should come before the BRBE support so that it can be applied
sooner rather than later. If another field is added to the end before 
expanding this field, then you will be stuck with assembling bits from 2 
fields.

>  include/uapi/linux/perf_event.h       | 10 ++++++++--
>  tools/include/uapi/linux/perf_event.h | 10 ++++++++--
>  tools/perf/util/branch.c              |  8 +++++++-
>  4 files changed, 29 insertions(+), 6 deletions(-)

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