linux-kernel - [PATCH v19 00/11] arm64/perf: Enable branch stack sampling

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Message-Id: <20250202-arm-brbe-v19-v19-0-1c1300802385@kernel.org>
Date: Sun, 02 Feb 2025 18:42:54 -0600
From: "Rob Herring (Arm)" <robh@...nel.org>
To: Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>, 
 Catalin Marinas <catalin.marinas@....com>, Jonathan Corbet <corbet@....net>, 
 Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
 Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
 Zenghui Yu <yuzenghui@...wei.com>, James Clark <james.clark@...aro.org>, 
 Anshuman Khandual <anshuman.khandual@....com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, 
 kvmarm@...ts.linux.dev, Mark Brown <broonie@...nel.org>
Subject: [PATCH v19 00/11] arm64/perf: Enable branch stack sampling

This series enables perf branch stack sampling support on arm64 via a 
v9.2 arch feature called Branch Record Buffer Extension (BRBE). Details 
on BRBE can be found in the Arm ARM[1] chapter D18.

I've picked up this series from Anshuman. This version has been reworked 
quite a bit by Mark and myself. The bulk of those changes are in patch 
11.

Patches 1-7 are new clean-ups/prep which stand on their own. They 
were previously posted here[2]. Please pick them up if there's no issues 
with them.

Patches 8-11 add BRBE support with the actual support in patch 11.

[1] https://developer.arm.com/documentation/ddi0487/latest/
[2] https://lore.kernel.org/all/20250107-arm-pmu-cleanups-v1-v1-0-313951346a25@kernel.org/

v19:
 - Drop saving of branch records when task scheduled out (Mark). Make 
   sched_task() callback actually get called. Enabling requires a call 
   to perf_sched_cb_inc(). So the saving of branch records never 
   happened.
 - Got rid of added armpmu ops. All BRBE support is contained within 
   pmuv3 code.
 - Fix freeze on overflow for VHE
 - The cycle counter doesn't freeze BRBE on overflow, so avoid assigning
   it when BRBE is enabled.
 - Drop all the Arm specific exception branches. Not a clear need for
   them.
 - Fix handling of branch 'cycles' reading. CC field is
   mantissa/exponent, not an integer.
 - Rework s/w filtering to better match h/w filtering
 - Reject events with disjoint event filter and branch filter or with 
   exclude_host set
 - Dropped perf test patch which has been applied for 6.14
 - Dropped patch "KVM: arm64: Explicitly handle BRBE traps as UNDEFINED"
   which has been applied for 6.14

v18:
 - https://lore.kernel.org/all/20240613061731.3109448-1-anshuman.khandual@arm.com/

For v1-v17, see the above link. Not going to duplicate it all here...

Signed-off-by: "Rob Herring (Arm)" <robh@...nel.org>
---
Anshuman Khandual (4):
      arm64/sysreg: Add BRBE registers and fields
      arm64: Handle BRBE booting requirements
      KVM: arm64: nvhe: Disable branch generation in nVHE guests
      perf: arm_pmuv3: Add support for the Branch Record Buffer Extension (BRBE)

Mark Rutland (3):
      perf: arm_pmu: Don't disable counter in armpmu_add()
      perf: arm_pmuv3: Don't disable counter in armv8pmu_enable_event()
      perf: arm_pmu: Move PMUv3-specific data

Rob Herring (Arm) (4):
      perf: arm_pmuv3: Call kvm_vcpu_pmu_resync_el0() before enabling counters
      perf: arm_v7_pmu: Drop obvious comments for enabling/disabling counters and interrupts
      perf: arm_v7_pmu: Don't disable counter in (armv7|krait_|scorpion_)pmu_enable_event()
      perf: apple_m1: Don't disable counter in m1_pmu_enable_event()

 Documentation/arch/arm64/booting.rst |  21 +
 arch/arm64/include/asm/el2_setup.h   |  86 +++-
 arch/arm64/include/asm/kvm_host.h    |   2 +
 arch/arm64/include/asm/sysreg.h      |  17 +-
 arch/arm64/kvm/debug.c               |   4 +
 arch/arm64/kvm/hyp/nvhe/debug-sr.c   |  32 ++
 arch/arm64/tools/sysreg              | 132 ++++++
 drivers/perf/Kconfig                 |  11 +
 drivers/perf/Makefile                |   1 +
 drivers/perf/apple_m1_cpu_pmu.c      |   4 -
 drivers/perf/arm_brbe.c              | 794 +++++++++++++++++++++++++++++++++++
 drivers/perf/arm_brbe.h              |  47 +++
 drivers/perf/arm_pmu.c               |  23 +-
 drivers/perf/arm_pmuv3.c             |  96 ++++-
 drivers/perf/arm_v7_pmu.c            |  50 ---
 include/linux/perf/arm_pmu.h         |  21 +-
 16 files changed, 1250 insertions(+), 91 deletions(-)
---
base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b
change-id: 20250129-arm-brbe-v19-24d5d9e5e623

Best regards,
-- 
Rob Herring (Arm) <robh@...nel.org>