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SubjectRe: [RFC V1 11/11] perf: Capture branch privilege information
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On 1/25/22 9:09 PM, James Clark wrote:
>
>
> On 24/01/2022 04:30, 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 flag PERF_SAMPLE_BRANCH_PRIV_SAVE. While
>> here, update the BRBE driver as required.
>>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
>> Cc: Jiri Olsa <jolsa@redhat.com>
>> Cc: Namhyung Kim <namhyung@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>
>> ---
>> drivers/perf/arm_pmu_brbe.c | 28 ++++++++++++++++++++++++
>> include/linux/perf_event.h | 5 +++++
>> include/uapi/linux/perf_event.h | 13 ++++++++++-
>> tools/include/uapi/linux/perf_event.h | 13 ++++++++++-
>> tools/perf/Documentation/perf-record.txt | 1 +
>> tools/perf/util/parse-branch-options.c | 1 +
>> 6 files changed, 59 insertions(+), 2 deletions(-)
>>
> [...]
>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>> index 361fdc6b87a0..4d77710f7a4e 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 privillege mode */
>
> privillege -> privilege

Fixed.

>
>> +
>> 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,
>> +
>
> Can you also add the new entry to the perf verbose printer otherwise it looks like
> it's not being set on branch_sample_type
> (as in when using ./perf record -j any_call,u,priv -vvv):

Sure, will do.

>
> static void __p_branch_sample_type(char *buf, size_t size, u64 value)
> {
> #define bit_name(n) { PERF_SAMPLE_BRANCH_##n, #n }
> struct bit_names bits[] = {
> bit_name(USER), bit_name(KERNEL), bit_name(HV), bit_name(ANY),
> bit_name(ANY_CALL), bit_name(ANY_RETURN), bit_name(IND_CALL),
> bit_name(ABORT_TX), bit_name(IN_TX), bit_name(NO_TX),
> bit_name(COND), bit_name(CALL_STACK), bit_name(IND_JUMP),
> bit_name(CALL), bit_name(NO_FLAGS), bit_name(NO_CYCLES),
> bit_name(HW_INDEX),
> { .name = NULL, }
> };
> #undef bit_name
> __p_bits(buf, size, value, bits);
> }
>
> PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT is also missing so it probably makes sense to add it
> at the same time as that was expanded for BRBE.

Posted a patch for PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT here but will update
for the new 'priv' request via this series.

https://lore.kernel.org/all/1643799443-15109-1-git-send-email-anshuman.khandual@arm.com/

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