linux-kernel - Re: [PATCH V7 0/6] arm64/perf: Enable branch stack sampling

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Date:   Wed, 11 Jan 2023 10:35:58 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        mark.rutland@....com
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Mark Brown <broonie@...nel.org>,
        James Clark <james.clark@....com>,
        Rob Herring <robh@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Suzuki Poulose <suzuki.poulose@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH V7 0/6] arm64/perf: Enable branch stack sampling



On 1/5/23 08:40, Anshuman Khandual wrote:
> This series enables perf branch stack sampling support on arm64 platform
> via a new arch feature called Branch Record Buffer Extension (BRBE). All
> relevant register definitions could be accessed here.
> 
> https://developer.arm.com/documentation/ddi0601/2021-12/AArch64-Registers
> 
> This series applies on v6.2-r2.
> 
> Changes in V7:
> 
> - Folded [PATCH 7/7] into [PATCH 3/7] which enables branch stack sampling event
> - Defined BRBFCR_EL1_BRANCH_FILTERS, BRBCR_EL1_DEFAULT_CONFIG in the header
> - Defined BRBFCR_EL1_DEFAULT_CONFIG in the header
> - Updated BRBCR_EL1_DEFAULT_CONFIG with BRBCR_EL1_FZP
> - Defined BRBCR_EL1_DEFAULT_TS in the header
> - Updated BRBCR_EL1_DEFAULT_CONFIG with BRBCR_EL1_DEFAULT_TS
> - Moved BRBCR_EL1_DEFAULT_CONFIG check inside branch_type_to_brbcr()
> - Moved down BRBCR_EL1_CC, BRBCR_EL1_MPRED later in branch_type_to_brbcr()
> - Also set BRBE in paused state in armv8pmu_branch_disable()
> - Dropped brbe_paused(), set_brbe_paused() helpers
> - Extracted error string via branch_filter_error_msg[] for armv8pmu_branch_valid()
> - Replaced brbe_v1p1 with brbe_version in struct brbe_hw_attr
> - Added valid_brbe_[cc, format, version]() helpers
> - Split a separate brbe_attributes_probe() from armv8pmu_branch_probe()
> - Capture event->attr.branch_sample_type earlier in armv8pmu_branch_valid()
> - Defined enum brbe_bank_idx with possible values for BRBE bank indices
> - Changed armpmu->hw_attr into armpmu->private
> - Added missing space in stub definition for armv8pmu_branch_valid()
> - Replaced both kmalloc() with kzalloc()
> - Added BRBE_BANK_MAX_ENTRIES
> - Updated comment for capture_brbe_flags()
> - Updated comment for struct brbe_hw_attr
> - Dropped space after type cast in couple of places
> - Replaced inverse with negation for testing BRBCR_EL1_FZP in armv8pmu_branch_read()
> - Captured cpuc->branches->branch_entries[idx] in a local variable
> - Dropped saved_priv from armv8pmu_branch_read()
> - Reorganize PERF_SAMPLE_BRANCH_NO_[CYCLES|NO_FLAGS] related configuration
> - Replaced with FIELD_GET() and FIELD_PREP() wherever applicable
> - Replaced BRBCR_EL1_TS_PHYSICAL with BRBCR_EL1_TS_VIRTUAL
> - Moved valid_brbe_nr(), valid_brbe_cc(), valid_brbe_format(), valid_brbe_version()
>   select_brbe_bank(), select_brbe_bank_index() helpers inside the C implementation
> - Reorganized brbe_valid_nr() and dropped the pr_warn() message
> - Changed probe sequence in brbe_attributes_probe()
> - Added 'brbcr' argument into capture_brbe_flags() to ascertain correct state
> - Disable BRBE before disabling the PMU event counter
> - Enable PERF_SAMPLE_BRANCH_HV filters when is_kernel_in_hyp_mode()
> - Guard armv8pmu_reset() & armv8pmu_sched_task() with arm_pmu_branch_stack_supported()

Gentle ping, any updates on this series ?