From nobody Mon Feb 9 11:47:45 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 2C4C9EB64DC for ; Tue, 11 Jul 2023 08:26:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231739AbjGKI0o (ORCPT ); Tue, 11 Jul 2023 04:26:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45214 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231661AbjGKI0d (ORCPT ); Tue, 11 Jul 2023 04:26:33 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3B8F51708; Tue, 11 Jul 2023 01:26:12 -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 F34A5D75; Tue, 11 Jul 2023 01:26:37 -0700 (PDT) Received: from a077893.arm.com (unknown [10.163.47.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D284C3F740; Tue, 11 Jul 2023 01:25:49 -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 - RESEND 08/10] arm64/perf: Add struct brbe_regset helper functions Date: Tue, 11 Jul 2023 13:54:53 +0530 Message-Id: <20230711082455.215983-9-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230711082455.215983-1-anshuman.khandual@arm.com> References: <20230711082455.215983-1-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" The primary abstraction level for fetching branch records from BRBE HW has been changed as 'struct brbe_regset', which contains storage for all three BRBE registers i.e BRBSRC, BRBTGT, BRBINF. Whether branch record processing happens in the task sched out path, or in the PMU IRQ handling path, these registers need to be extracted from the HW. Afterwards both live and stored sets need to be stitched together to create final branch records set. This adds required helper functions for such operations. 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 --- drivers/perf/arm_brbe.c | 121 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 121 insertions(+) diff --git a/drivers/perf/arm_brbe.c b/drivers/perf/arm_brbe.c index a74459445813..203cd4f350d5 100644 --- a/drivers/perf/arm_brbe.c +++ b/drivers/perf/arm_brbe.c @@ -44,6 +44,127 @@ static void select_brbe_bank(int bank) isb(); } =20 +static bool __read_brbe_regset(struct brbe_regset *entry, int idx) +{ + entry->brbinf =3D get_brbinf_reg(idx); + + if (brbe_invalid(entry->brbinf)) + return false; + + entry->brbsrc =3D get_brbsrc_reg(idx); + entry->brbtgt =3D get_brbtgt_reg(idx); + return true; +} + +/* + * Read all BRBE entries in HW until the first invalid entry. + * + * The caller must ensure that the BRBE is not concurrently modifying these + * branch entries. + */ +static int capture_brbe_regset(struct brbe_regset *buf, int nr_hw_entries) +{ + int idx =3D 0; + + select_brbe_bank(BRBE_BANK_IDX_0); + while (idx < nr_hw_entries && idx <=3D BRBE_BANK0_IDX_MAX) { + if (!__read_brbe_regset(&buf[idx], idx)) + return idx; + idx++; + } + + select_brbe_bank(BRBE_BANK_IDX_1); + while (idx < nr_hw_entries && idx <=3D BRBE_BANK1_IDX_MAX) { + if (!__read_brbe_regset(&buf[idx], idx)) + return idx; + idx++; + } + return idx; +} + +/* + * This function concatenates branch records from stored and live buffer + * up to maximum nr_max records and the stored buffer holds the resultant + * buffer. The concatenated buffer contains all the branch records from + * the live buffer but might contain some from stored buffer considering + * the maximum combined length does not exceed 'nr_max'. + * + * Stored records Live records + * ------------------------------------------------^ + * | S0 | L0 | Newest | + * --------------------------------- | + * | S1 | L1 | | + * --------------------------------- | + * | S2 | L2 | | + * --------------------------------- | + * | S3 | L3 | | + * --------------------------------- | + * | S4 | L4 | nr_max + * --------------------------------- | + * | | L5 | | + * --------------------------------- | + * | | L6 | | + * --------------------------------- | + * | | L7 | | + * --------------------------------- | + * | | | | + * --------------------------------- | + * | | | Oldest | + * ------------------------------------------------V + * + * + * S0 is the newest in the stored records, where as L7 is the oldest in + * the live records. Unless the live buffer is detected as being full + * thus potentially dropping off some older records, L7 and S0 records + * are contiguous in time for a user task context. The stitched buffer + * here represents maximum possible branch records, contiguous in time. + * + * Stored records Live records + * ------------------------------------------------^ + * | L0 | L0 | Newest | + * --------------------------------- | + * | L0 | L1 | | + * --------------------------------- | + * | L2 | L2 | | + * --------------------------------- | + * | L3 | L3 | | + * --------------------------------- | + * | L4 | L4 | nr_max + * --------------------------------- | + * | L5 | L5 | | + * --------------------------------- | + * | L6 | L6 | | + * --------------------------------- | + * | L7 | L7 | | + * --------------------------------- | + * | S0 | | | + * --------------------------------- | + * | S1 | | Oldest | + * ------------------------------------------------V + * | S2 | <----| + * ----------------- | + * | S3 | <----| Dropped off after nr_max + * ----------------- | + * | S4 | <----| + * ----------------- + */ +static int stitch_stored_live_entries(struct brbe_regset *stored, + struct brbe_regset *live, + int nr_stored, int nr_live, + int nr_max) +{ + int nr_move =3D min(nr_stored, nr_max - nr_live); + + /* Move the tail of the buffer to make room for the new entries */ + memmove(&stored[nr_live], &stored[0], nr_move * sizeof(*stored)); + + /* Copy the new entries into the head of the buffer */ + memcpy(&stored[0], &live[0], nr_live * sizeof(*stored)); + + /* Return the number of entries in the stitched buffer */ + return min(nr_live + nr_stored, nr_max); +} + /* * Generic perf branch filters supported on BRBE * --=20 2.25.1