[PATCH V3 0/7] arm64/perf: Enable branch stack sampling

From: Anshuman Khandual
Date: Thu Sep 29 2022 - 03:59:19 EST


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 v6.0-rc5 after the BRBE related perf ABI changes series
(V7) that was posted earlier, and a branch sample filter helper patch.

https://lore.kernel.org/all/20220824044822.70230-1-anshuman.khandual@xxxxxxx/

https://lore.kernel.org/all/20220906084414.396220-1-anshuman.khandual@xxxxxxx/

Changes in V3:

- Moved brbe_stack from the stack and now dynamically allocated
- Return PERF_BR_PRIV_UNKNOWN instead of -1 in brbe_fetch_perf_priv()
- Moved BRBIDR0, BRBCR, BRBFCR registers and fields into tools/sysreg
- Created dummy BRBINF_EL1 field definitions in tools/sysreg
- Dropped ARMPMU_EVT_PRIV framework which cached perfmon_capable()
- Both exception and exception return branche records are now captured
only if the event has PERF_SAMPLE_BRANCH_KERNEL which would already
been checked in generic perf via perf_allow_kernel()

Changes in V2:

https://lore.kernel.org/all/20220908051046.465307-1-anshuman.khandual@xxxxxxx/

- Dropped branch sample filter helpers consolidation patch from this series
- Added new hw_perf_event.flags element ARMPMU_EVT_PRIV to cache perfmon_capable()
- Use cached perfmon_capable() while configuring BRBE branch record filters

Changes in V1:

https://lore.kernel.org/linux-arm-kernel/20220613100119.684673-1-anshuman.khandual@xxxxxxx/

- Added CONFIG_PERF_EVENTS wrapper for all branch sample filter helpers
- Process new perf branch types via PERF_BR_EXTEND_ABI

Changes in RFC V2:

https://lore.kernel.org/linux-arm-kernel/20220412115455.293119-1-anshuman.khandual@xxxxxxx/

- Added branch_sample_priv() while consolidating other branch sample filter helpers
- Changed all SYS_BRBXXXN_EL1 register definition encodings per Marc
- Changed the BRBE driver as per proposed BRBE related perf ABI changes (V5)
- Added documentation for struct arm_pmu changes, updated commit message
- Updated commit message for BRBE detection infrastructure patch
- PERF_SAMPLE_BRANCH_KERNEL gets checked during arm event init (outside the driver)
- Branch privilege state capture mechanism has now moved inside the driver

Changes in RFC V1:

https://lore.kernel.org/all/1642998653-21377-1-git-send-email-anshuman.khandual@xxxxxxx/

Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: James Clark <james.clark@xxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Suzuki Poulose <suzuki.poulose@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-perf-users@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx


Anshuman Khandual (7):
arm64/perf: Add BRBE registers and fields
arm64/perf: Update struct arm_pmu for BRBE
arm64/perf: Update struct pmu_hw_events for BRBE
driver/perf/arm_pmu_platform: Add support for BRBE attributes detection
arm64/perf: Drive BRBE from perf event states
arm64/perf: Add BRBE driver
arm64/perf: Enable branch stack sampling

arch/arm64/include/asm/sysreg.h | 107 ++++++++
arch/arm64/kernel/perf_event.c | 48 ++++
arch/arm64/tools/sysreg | 159 ++++++++++++
drivers/perf/Kconfig | 11 +
drivers/perf/Makefile | 1 +
drivers/perf/arm_pmu.c | 73 +++++-
drivers/perf/arm_pmu_brbe.c | 447 ++++++++++++++++++++++++++++++++
drivers/perf/arm_pmu_brbe.h | 259 ++++++++++++++++++
drivers/perf/arm_pmu_platform.c | 34 +++
include/linux/perf/arm_pmu.h | 67 +++++
10 files changed, 1203 insertions(+), 3 deletions(-)
create mode 100644 drivers/perf/arm_pmu_brbe.c
create mode 100644 drivers/perf/arm_pmu_brbe.h

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2.25.1