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SubjectRe: [PATCH V4 04/10] perf: Capture branch privilege information
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On 15/03/2022 05:35, Anshuman Khandual wrote:
> Platforms like arm64 could capture privilege level information for all the
> branch records. Hence this adds a new element in the struct branch_entry to
> record the privilege level information, which could be requested through a
> new event.attr.branch_sample_type based flag PERF_SAMPLE_BRANCH_PRIV_SAVE.
> This flag helps user choose whether privilege information is captured.
>

Reviewed-by: James Clark <james.clark@arm.com>

> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Jiri Olsa <jolsa@redhat.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Will Deacon <will@kernel.org>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-perf-users@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> include/uapi/linux/perf_event.h | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index d29280adc3c4..193dba2ecdc1 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -204,6 +204,8 @@ enum perf_branch_sample_type_shift {
>
> PERF_SAMPLE_BRANCH_HW_INDEX_SHIFT = 17, /* save low level index of raw branch records */
>
> + PERF_SAMPLE_BRANCH_PRIV_SAVE_SHIFT = 18, /* save privilege mode */
> +
> PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */
> };
>
> @@ -233,6 +235,8 @@ enum perf_branch_sample_type {
>
> PERF_SAMPLE_BRANCH_HW_INDEX = 1U << PERF_SAMPLE_BRANCH_HW_INDEX_SHIFT,
>
> + PERF_SAMPLE_BRANCH_PRIV_SAVE = 1U << PERF_SAMPLE_BRANCH_PRIV_SAVE_SHIFT,
> +
> PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
> };
>
> @@ -271,6 +275,13 @@ enum {
> PERF_BR_NEW_MAX,
> };
>
> +enum {
> + PERF_BR_PRIV_UNKNOWN = 0,
> + PERF_BR_PRIV_USER = 1,
> + PERF_BR_PRIV_KERNEL = 2,
> + PERF_BR_PRIV_HV = 3,
> +};
> +
> #define PERF_SAMPLE_BRANCH_PLM_ALL \
> (PERF_SAMPLE_BRANCH_USER|\
> PERF_SAMPLE_BRANCH_KERNEL|\
> @@ -1386,7 +1397,8 @@ struct perf_branch_entry {
> cycles:16, /* cycle count to last branch */
> type:4, /* branch type */
> new_type:4, /* additional branch type */
> - reserved:36;
> + priv:3, /* privilege level */
> + reserved:33;
> };
>
> union perf_sample_weight {

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