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Message-ID: <2d7297b3-9a22-626b-9840-a4eaab4b94e8@arm.com>
Date: Tue, 25 Jan 2022 16:58:20 +0000
From: James Clark <james.clark@....com>
To: Anshuman Khandual <anshuman.khandual@....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 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;
};
};
};
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.
>
> union perf_sample_weight {
> diff --git a/tools/perf/util/branch.c b/tools/perf/util/branch.c
> index 74e5e67b1779..1e216ea2e2a8 100644
> --- a/tools/perf/util/branch.c
> +++ b/tools/perf/util/branch.c
> @@ -54,7 +54,13 @@ const char *branch_type_name(int type)
> "IRQ",
> "FIQ",
> "DEBUG_HALT",
> - "DEBUG_EXIT"
> + "DEBUG_EXIT",
> + "DEBUG_INST",
> + "DEBUG_DATA",
> + "FAULT_ALGN",
> + "FAULT_DATA",
> + "FAULT_INST",
> + "SERROR"
> };
>
> if (type >= 0 && type < PERF_BR_MAX)
>
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