From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BA4E4CD6E7D for ; Fri, 5 Jun 2026 13:54:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=J0R4eBG2pFYNvoAv6aArk0OSJ05uyndW9ZEtAs++bJk=; b=Rp2QML+s15kJBObYprXMCsmYhV Y8GJPhDsjkqM4k64SeXAAyA9Qfv6+wLB3mmKTy+Ro61LwicUOdoaVGToTwl1aHTHFW420a5R2rhMS xTF3PSlrrNVbY5Omvk6qakcIJ2Q4L946+CmxiwGC0N6zmJsPbLHzyzdHSsva7c2+MIJxB1jwbmK40 YQLACQOj3BuL+zLrxK5jUC7goxWmmwJcY9vVU5Con49F4os6Y1f7gcAAK3qXSC80NXar/GybSdL97 izr/6Yp2ij/2pKCMMVkm95PSGgrqaj88YGO9aqmmdGXpkPXYb615ryOroAtwaomPIjVcmlUUSOhEL /8gngjVQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wVUzj-00000000hC1-1ZFX; Fri, 05 Jun 2026 13:53:55 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wVUzi-00000000hBv-0Pxa for linux-arm-kernel@lists.infradead.org; Fri, 05 Jun 2026 13:53:54 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 07217601E3; Fri, 5 Jun 2026 13:53:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 82EE71F00898; Fri, 5 Jun 2026 13:53:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780667632; bh=J0R4eBG2pFYNvoAv6aArk0OSJ05uyndW9ZEtAs++bJk=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=A9St+RvVrzyZl1ZMltNKutIQ4v56AK9zs+Vr6o/Gw9W8YZzAgleY83Gj5tnrWqydv AdT056a/FPR/9138v3+ImH4wqZtMbBAYNqbYRQPuIe9Tt4Q8tsPXSyqMYCwyrd4RMv A77jBow2Hfw7i08PjR8ogFZQ9YU3f7fvI7U+y+5KYtTh6fESF/Ezz9WCfT+21oizXA 5vS0IiejhSADD+AjeTi1nsCORC1GBX2JrZy+nrPEcfktzLtTj85ZM7HuO9kxmfAgeO abA/pREttTxluz8Ydipn9WHLOzoipIwUI1hZwuS7laf3zAoMttwO/y/Z0OatWqDVf9 sc9zAKaZVrkOQ== Date: Fri, 5 Jun 2026 08:53:51 -0500 From: Rob Herring To: Puranjay Mohan Cc: bpf@vger.kernel.org, Puranjay Mohan , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , Will Deacon , Mark Rutland , Catalin Marinas , Leo Yan , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , James Clark , Ian Rogers , Adrian Hunter , Shuah Khan , Breno Leitao , Ravi Bangoria , Stephane Eranian , Kumar Kartikeya Dwivedi , Usama Arif , linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v4 3/4] perf/arm64: Add BRBE support for bpf_get_branch_snapshot() Message-ID: <20260605135351.GA3587043-robh@kernel.org> References: <20260527121207.2312181-1-puranjay@kernel.org> <20260527121207.2312181-4-puranjay@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260527121207.2312181-4-puranjay@kernel.org> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, May 27, 2026 at 05:11:59AM -0700, Puranjay Mohan wrote: > Enable bpf_get_branch_snapshot() on ARM64 by implementing the > perf_snapshot_branch_stack static call for BRBE. > > BRBE is paused before masking exceptions to avoid branch buffer > pollution from trace_hardirqs_off(). Exceptions are then masked with > local_daif_save() to prevent PMU overflow pseudo-NMIs from interfering. > If an overflow between pause and DAIF save re-enables BRBE, the snapshot > detects this via BRBFCR_EL1.PAUSED and bails out. > > Branch records are read using perf_entry_from_brbe_regset() with a NULL > event pointer to bypass event-specific filtering. The buffer is > invalidated after reading. > > Introduce a for_each_brbe_entry() iterator to deduplicate bank > iteration between brbe_read_filtered_entries() and the snapshot. > > Signed-off-by: Puranjay Mohan > --- > drivers/perf/arm_brbe.c | 127 ++++++++++++++++++++++++++++++++------- > drivers/perf/arm_brbe.h | 9 +++ > drivers/perf/arm_pmuv3.c | 5 +- > 3 files changed, 119 insertions(+), 22 deletions(-) Reviewed-by: Rob Herring (Arm)