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Message-ID: <17dc4a62-14d6-c0f2-b428-c1525411b1e0@arm.com>
Date: Fri, 28 Jan 2022 09:44:22 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: James Clark <james.clark@....com>, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Cc: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
linux-perf-users@...r.kernel.org,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...nel.org>
Subject: Re: [RFC V1 10/11] perf: Expand perf_branch_entry.type
On 1/25/22 10:28 PM, James Clark wrote:
>
> On 24/01/2022 04:30, 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 <peterz@...radead.org>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
>> Cc: Jiri Olsa <jolsa@...hat.com>
>> Cc: Namhyung Kim <namhyung@...nel.org>
>> Cc: Will Deacon <will@...nel.org>
>> Cc: linux-arm-kernel@...ts.infradead.org
>> Cc: linux-perf-users@...r.kernel.org
>> Cc: linux-kernel@...r.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
>> ---
>> drivers/perf/arm_pmu_brbe.c | 7 ++++++-
>> 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(-)
>>
>> diff --git a/drivers/perf/arm_pmu_brbe.c b/drivers/perf/arm_pmu_brbe.c
>> index 8d27ad868359..7cd1208c6c58 100644
>> --- a/drivers/perf/arm_pmu_brbe.c
>> +++ b/drivers/perf/arm_pmu_brbe.c
>> @@ -253,12 +253,17 @@ static int brbe_fetch_perf_type(u64 brbinf)
>> case BRBINF_TYPE_DEBUG_EXIT:
>> return PERF_BR_DEBUG_EXIT;
>> case BRBINF_TYPE_SERROR:
>> + return PERF_BR_SERROR;
>> case BRBINF_TYPE_INST_DEBUG:
>> + return PERF_BR_DEBUG_INST;
>> case BRBINF_TYPE_DATA_DEBUG:
>> + return PERF_BR_DEBUG_DATA;
>> case BRBINF_TYPE_ALGN_FAULT:
>> + return PERF_BR_FAULT_ALGN;
>> case BRBINF_TYPE_INST_FAULT:
>> + return PERF_BR_FAULT_INST;
>> case BRBINF_TYPE_DATA_FAULT:
>> - return PERF_BR_UNKNOWN;
>> + return PERF_BR_FAULT_DATA;
>> default:
>> pr_warn("unknown branch type captured\n");
>> return PERF_BR_UNKNOWN;
>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>> index b91d0f575d0c..361fdc6b87a0 100644
>> --- a/include/uapi/linux/perf_event.h
>> +++ b/include/uapi/linux/perf_event.h
>> @@ -256,6 +256,12 @@ enum {
>> PERF_BR_FIQ = 13, /* fiq */
>> PERF_BR_DEBUG_HALT = 14, /* debug halt */
>> PERF_BR_DEBUG_EXIT = 15, /* debug exit */
>> + PERF_BR_DEBUG_INST = 16, /* instruciton debug */
>> + PERF_BR_DEBUG_DATA = 17, /* data debug */
>> + PERF_BR_FAULT_ALGN = 18, /* alignment fault */
>> + PERF_BR_FAULT_DATA = 19, /* data fault */
>> + PERF_BR_FAULT_INST = 20, /* instruction fault */
>> + PERF_BR_SERROR = 21, /* system error */
>> PERF_BR_MAX,
>> };
>>
>> @@ -1370,8 +1376,8 @@ struct perf_branch_entry {
>> in_tx:1, /* in transaction */
>> abort:1, /* transaction abort */
>> cycles:16, /* cycle count to last branch */
>> - type:4, /* branch type */
>> - reserved:40;
>> + type:6, /* branch type */
>> + reserved:38;
>> };
>>
>> union perf_sample_weight {
>> diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
>> index 1882054e8684..9a82b8aaed93 100644
>> --- a/tools/include/uapi/linux/perf_event.h
>> +++ b/tools/include/uapi/linux/perf_event.h
>> @@ -256,6 +256,12 @@ enum {
>> PERF_BR_FIQ = 13, /* fiq */
>> PERF_BR_DEBUG_HALT = 14, /* debug halt */
>> PERF_BR_DEBUG_EXIT = 15, /* debug exit */
>> + PERF_BR_DEBUG_INST = 16, /* instruciton debug */
>> + PERF_BR_DEBUG_DATA = 17, /* data debug */
>> + PERF_BR_FAULT_ALGN = 18, /* alignment fault */
>> + PERF_BR_FAULT_DATA = 19, /* data fault */
>> + PERF_BR_FAULT_INST = 20, /* instruction fault */
>> + PERF_BR_SERROR = 21, /* system error */
>> PERF_BR_MAX,
>> };
>>
>> @@ -1370,8 +1376,8 @@ struct perf_branch_entry {
>> in_tx:1, /* in transaction */
>> abort:1, /* transaction abort */
>> cycles:16, /* cycle count to last branch */
>> - type:4, /* branch type */
>> - reserved:40;
>> + type:6, /* branch type */
>> + reserved:38;
>> };
> There's another copy of this struct in branch.h that is used to access the same data in
> perf which also needs updating:
>
> struct branch_flags {
> union {
> u64 value;
> struct {
> u64 mispred:1;
> u64 predicted:1;
> u64 in_tx:1;
> u64 abort:1;
> u64 cycles:16;
> u64 type:4;
> u64 reserved:40;
> };
> };
> };
Sure, thanks for the catch. Will fix it.
>
> It's never assigned directly but there is some casting stuff going on in
> evsel__parse_sample() and it eventually ends up being used to access branch
> records. Same applies to the privilege data change.
>
Okay, will do the necessary changes in the privilege data patch.
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