From nobody Mon Feb 9 16:45:28 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E36AEB64D8 for ; Thu, 22 Jun 2023 06:56:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231252AbjFVG4K (ORCPT ); Thu, 22 Jun 2023 02:56:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231243AbjFVGzg (ORCPT ); Thu, 22 Jun 2023 02:55:36 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 7A33D26A5; Wed, 21 Jun 2023 23:55:08 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0775C14BF; Wed, 21 Jun 2023 23:55:40 -0700 (PDT) Received: from a077893.blr.arm.com (unknown [10.162.40.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 6A0603F777; Wed, 21 Jun 2023 23:54:51 -0700 (PDT) From: Anshuman Khandual To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com Cc: Anshuman Khandual , Mark Brown , James Clark , Rob Herring , Marc Zyngier , Suzuki Poulose , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , linux-perf-users@vger.kernel.org Subject: [PATCH V13 09/10] arm64/perf: Implement branch records save on task sched out Date: Thu, 22 Jun 2023 12:23:50 +0530 Message-Id: <20230622065351.1092893-10-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230622065351.1092893-1-anshuman.khandual@arm.com> References: <20230622065351.1092893-1-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This modifies current armv8pmu_sched_task(), to implement a branch records save mechanism via armv8pmu_branch_save() when a task scheds out of a cpu. BRBE is paused and disabled for all exception levels before branch records get captured, which then get concatenated with all existing stored records present in the task context maintaining the contiguity. Although the final length of the concatenated buffer does not exceed implemented BRBE length. Cc: Catalin Marinas Cc: Will Deacon Cc: Mark Rutland Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Tested-by: James Clark Acked-by: Mark Rutland Signed-off-by: Anshuman Khandual --- arch/arm/include/asm/arm_pmuv3.h | 1 + arch/arm64/include/asm/perf_event.h | 2 ++ drivers/perf/arm_brbe.c | 30 +++++++++++++++++++++++++++++ drivers/perf/arm_pmuv3.c | 14 ++++++++++++-- 4 files changed, 45 insertions(+), 2 deletions(-) diff --git a/arch/arm/include/asm/arm_pmuv3.h b/arch/arm/include/asm/arm_pm= uv3.h index 1f948eaed1c6..6c65357de94d 100644 --- a/arch/arm/include/asm/arm_pmuv3.h +++ b/arch/arm/include/asm/arm_pmuv3.h @@ -254,5 +254,6 @@ static inline void armv8pmu_branch_probe(struct arm_pmu= *arm_pmu) { } static inline void armv8pmu_branch_reset(void) { } static inline int armv8pmu_task_ctx_cache_alloc(struct arm_pmu *arm_pmu) {= return 0; } static inline void armv8pmu_task_ctx_cache_free(struct arm_pmu *arm_pmu) {= } +static inline void armv8pmu_branch_save(struct arm_pmu *arm_pmu, void *ctx= ) { } #endif #endif diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/p= erf_event.h index b0c12a5882df..36e7dfb466a6 100644 --- a/arch/arm64/include/asm/perf_event.h +++ b/arch/arm64/include/asm/perf_event.h @@ -40,6 +40,7 @@ void armv8pmu_branch_probe(struct arm_pmu *arm_pmu); void armv8pmu_branch_reset(void); int armv8pmu_task_ctx_cache_alloc(struct arm_pmu *arm_pmu); void armv8pmu_task_ctx_cache_free(struct arm_pmu *arm_pmu); +void armv8pmu_branch_save(struct arm_pmu *arm_pmu, void *ctx); #else static inline void armv8pmu_branch_read(struct pmu_hw_events *cpuc, struct= perf_event *event) { @@ -66,6 +67,7 @@ static inline void armv8pmu_branch_probe(struct arm_pmu *= arm_pmu) { } static inline void armv8pmu_branch_reset(void) { } static inline int armv8pmu_task_ctx_cache_alloc(struct arm_pmu *arm_pmu) {= return 0; } static inline void armv8pmu_task_ctx_cache_free(struct arm_pmu *arm_pmu) {= } +static inline void armv8pmu_branch_save(struct arm_pmu *arm_pmu, void *ctx= ) { } #endif #endif #endif diff --git a/drivers/perf/arm_brbe.c b/drivers/perf/arm_brbe.c index 203cd4f350d5..2177632befa6 100644 --- a/drivers/perf/arm_brbe.c +++ b/drivers/perf/arm_brbe.c @@ -165,6 +165,36 @@ static int stitch_stored_live_entries(struct brbe_regs= et *stored, return min(nr_live + nr_stored, nr_max); } =20 +static int brbe_branch_save(struct brbe_regset *live, int nr_hw_entries) +{ + u64 brbfcr =3D read_sysreg_s(SYS_BRBFCR_EL1); + int nr_live; + + write_sysreg_s(brbfcr | BRBFCR_EL1_PAUSED, SYS_BRBFCR_EL1); + isb(); + + nr_live =3D capture_brbe_regset(live, nr_hw_entries); + + write_sysreg_s(brbfcr & ~BRBFCR_EL1_PAUSED, SYS_BRBFCR_EL1); + isb(); + + return nr_live; +} + +void armv8pmu_branch_save(struct arm_pmu *arm_pmu, void *ctx) +{ + struct arm64_perf_task_context *task_ctx =3D ctx; + struct brbe_regset live[BRBE_MAX_ENTRIES]; + int nr_live, nr_store, nr_hw_entries; + + nr_hw_entries =3D brbe_get_numrec(arm_pmu->reg_brbidr); + nr_live =3D brbe_branch_save(live, nr_hw_entries); + nr_store =3D task_ctx->nr_brbe_records; + nr_store =3D stitch_stored_live_entries(task_ctx->store, live, nr_store, + nr_live, nr_hw_entries); + task_ctx->nr_brbe_records =3D nr_store; +} + /* * Generic perf branch filters supported on BRBE * diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c index 3c079051a63a..53f404618891 100644 --- a/drivers/perf/arm_pmuv3.c +++ b/drivers/perf/arm_pmuv3.c @@ -907,9 +907,19 @@ static int armv8pmu_user_event_idx(struct perf_event *= event) static void armv8pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bo= ol sched_in) { struct arm_pmu *armpmu =3D to_arm_pmu(pmu_ctx->pmu); + void *task_ctx =3D pmu_ctx ? pmu_ctx->task_ctx_data : NULL; =20 - if (sched_in && armpmu->has_branch_stack) - armv8pmu_branch_reset(); + if (armpmu->has_branch_stack) { + /* Save branch records in task_ctx on sched out */ + if (task_ctx && !sched_in) { + armv8pmu_branch_save(armpmu, task_ctx); + return; + } + + /* Reset branch records on sched in */ + if (sched_in) + armv8pmu_branch_reset(); + } } =20 /* --=20 2.25.1