From: Raphael Gault <email@example.com> To: firstname.lastname@example.org, email@example.com Cc: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, Raphael Gault <firstname.lastname@example.org>, email@example.com Subject: [PATCH v4 0/7] arm64: Enable access to pmu registers by user-space Date: Thu, 22 Aug 2019 15:42:13 +0100 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) Hi, Changes since v3: * Rebased on will/for-next/perf in order to include this patch  * Re-introduce `mrs` hook used in previous versions * Invert cpu feature to track homogeneity instead of heterogeneity * Introduce accessor for boot_cpu_data (see second commit for more info) * Apply Mark Rutland's comments The perf user-space tool relies on the PMU to monitor events. It offers an abstraction layer over the hardware counters since the underlying implementation is cpu-dependent. We want to allow userspace tools to have access to the registers storing the hardware counters' values directly. This targets specifically self-monitoring tasks in order to reduce the overhead by directly accessing the registers without having to go through the kernel. In order to do this we need to setup the pmu so that it exposes its registers to userspace access. The first patch add a test to the perf tool so that we can test that the access to the registers works correctly from userspace. The second patch introduces an accessor for `boot_cpu_data` which is static. Including cpu.h turned out to cause a chain of dependencies so I opted for the accessor since it is not much used. The third patch add a capability in the arm64 cpufeatures framework in order to detect when we are running on a homogeneous system. The fourth patch re introduces the hooks to handling undefined instruction for `mrs` instructions on pmu-related registers. The fifth patch focuses on the armv8 pmuv3 PMU support and makes sure that the access to the pmu registers is enable and that the userspace have access to the relevent information in order to use them. The sixth patch put in place callbacks to enable access to the hardware counters from userspace when a compatible event is opened using the perf API. The seventh patch adds a short documentation about PMU counters direct access from userspace. : https://lkml.org/lkml/2019/8/20/875 Raphael Gault (7): perf: arm64: Add test to check userspace access to hardware counters. arm64: cpu: Add accessor for boot_cpu_data arm64: cpufeature: Add feature to detect homogeneous systems arm64: pmu: Add hook to handle pmu-related undefined instructions arm64: pmu: Add function implementation to update event index in userpage. arm64: perf: Enable pmu counter direct access for perf event on armv8 Documentation: arm64: Document PMU counters access from userspace .../arm64/pmu_counter_user_access.txt | 42 +++ arch/arm64/include/asm/cpu.h | 2 +- arch/arm64/include/asm/cpucaps.h | 3 +- arch/arm64/include/asm/cpufeature.h | 10 + arch/arm64/include/asm/mmu.h | 6 + arch/arm64/include/asm/mmu_context.h | 2 + arch/arm64/include/asm/perf_event.h | 14 + arch/arm64/kernel/cpufeature.c | 32 ++- arch/arm64/kernel/cpuinfo.c | 7 +- arch/arm64/kernel/perf_event.c | 77 ++++++ drivers/perf/arm_pmu.c | 54 ++++ include/linux/perf/arm_pmu.h | 2 + tools/perf/arch/arm64/include/arch-tests.h | 7 + tools/perf/arch/arm64/tests/Build | 1 + tools/perf/arch/arm64/tests/arch-tests.c | 4 + tools/perf/arch/arm64/tests/user-events.c | 254 ++++++++++++++++++ 16 files changed, 512 insertions(+), 5 deletions(-) create mode 100644 Documentation/arm64/pmu_counter_user_access.txt create mode 100644 tools/perf/arch/arm64/tests/user-events.c -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list email@example.com http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2019-08-22 14:42 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-22 14:42 Raphael Gault [this message] 2019-08-22 14:42 ` [PATCH v4 1/7] perf: arm64: Add test to check userspace access to hardware counters Raphael Gault 2019-08-27 11:17 ` Jonathan Cameron 2020-06-03 16:19 ` Rob Herring 2019-08-22 14:42 ` [PATCH v4 2/7] arm64: cpu: Add accessor for boot_cpu_data Raphael Gault 2019-08-22 14:42 ` [PATCH v4 3/7] arm64: cpufeature: Add feature to detect homogeneous systems Raphael Gault 2019-08-22 14:42 ` [PATCH v4 4/7] arm64: pmu: Add hook to handle pmu-related undefined instructions Raphael Gault 2019-08-22 14:42 ` [PATCH v4 5/7] arm64: pmu: Add function implementation to update event index in userpage Raphael Gault 2019-08-22 14:42 ` [PATCH v4 6/7] arm64: perf: Enable pmu counter direct access for perf event on armv8 Raphael Gault 2019-08-22 16:39 ` Jonathan Cameron 2019-08-22 14:42 ` [PATCH v4 7/7] Documentation: arm64: Document PMU counters access from userspace Raphael Gault
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