From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792560661; b=S/hpcomlPzYvykIbN3kaCr4lDER2gQoy1BJ6J+8Vn36LuFLjeyoxxSi7ooEcizlQE67p lQ1RkCq+Li4oi/hpQYg23LfXAl+JH+XU0lOC4UI9dhIByry9w3BqwjXMBlTBigEfN63Nl ZkoQtXqLMlZ9XuQu1psWQmb/4vlW5MdcJGNKqT22vwLYRvmXCYovkiNbMKrxBzda54Xks keYgB0vNfQNdltJ6yCUiF8Dy4LLBYC/JLYbjO5tLxwngpywNZu0E76HOMoQ07YI6DD6pc 3IZisNAvVNGNSc5WLf3Qt11r0gzYSys+ZVaBbd1MoqPBKhfW1zyYCBQB6aE6q30d1TQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792560661; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=U+g7h2juA7dAlMAf1gOHT4E7BqjnNC9/hlvwsTUO0KU=; b=DWyJI7Nf4TWZzEpEnGPPJzLrqKTtauAm+V5S2ygS93LBG4p63VOWSrVfbtMKQyOwLHHG DIy769mTHtYqutaZ25BlF7gi/8kVA0MHopvVe5rWrxih6suQEGb39x99qAdYfIwCVZOaz lKt/xyuOwsPh2bAZ7d/kwsKWbXhyLKy6YDBsdt8X1NQ3Oz90yZUcwqLNsWWjH+dZ4OW6K rV0QisWT81kbk3xviuhIjt2J5HD3nydpGeZs1IPklXttM9jUKJrv5uHG/siHZCP59aUML WOcoQ3CbAeFvcZlbiOGGjeb8hZ/5KzL2Jq/SCQnPL9jifDJsm9nGrnP1ds/ef2iGhCg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=dCj0uL0B; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9AD38606A319 for ; Wed, 21 Oct 2026 05:31:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=dCj0uL0B Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1431D1F000C9; Wed, 21 Oct 2026 05:31:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792560661; bh=U+g7h2juA7dAlMAf1gOHT4E7BqjnNC9/hlvwsTUO0KU=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=dCj0uL0BdZilxRuL4L2+dJykItSsxzsynHFG2FzDexX3HnFLkXbhUbBkZVwqZ0PpM Yl3T51j5TCDKCa5nLeax/Fq39WmMrv0vDObcoHKUFT42+2eeysIMyIf9Mrm9jBSgVE a3FtIj5l38pd4daMnzBWTCOYce+Aass0v5zHszRAXLOjMv8XXlWl32e0jrWyMqZ2mo WHS8oKA19ZPeOJUFonttpG3WsA+5HJU0rGYBrpiqPQ9wzpppUzV95t7hW+8E8ePmPM ohTZJKee6CKzmaZIj68l7y3BgX3ykkoZNxeD+gLveulJXcGkgjOCVrHKOqz6bp63iG WVBK6eF3TrCFA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [Patch v4 2/5] perf/x86/amd/lbr: Limit branch snapshots to valid entries Reply-To: sashiko-reviews@lists.linux.dev To: "Dapeng Mi" Cc: linux-perf-users@vger.kernel.org In-Reply-To: <20261021050711.4043703-3-dapeng1.mi@linux.intel.com> References: <20261021050711.4043703-1-dapeng1.mi@linux.intel.com> <20261021050711.4043703-3-dapeng1.mi@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 21 Oct 2026 05:31:00 +0000 X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > From: Sandipan Das >=20 > The branch snapshot callback used by bpf_get_branch_snapshot() copies > up to x86_pmu.lbr_nr entries from cpuc->lbr_entries[], even when the > last LBR read kept fewer branches. The entries past lbr_stack.nr are > invalid, but they end up reaching BPF programs. >=20 > Limit copying to lbr_stack.nr entries and also reset lbr_stack.nr when > amd_pmu_lbr_read() skips reading the registers, so that a stale count > is never reused. >=20 > Fixes: a4d18112e531 ("perf/x86/amd: Support capturing LBR from software e= vents") > Reported-by: Sashiko > Closes: https://lore.kernel.org/all/sashiko-outbox-163130@kernel.org/ > Signed-off-by: Sandipan Das > Reviewed-by: Dapeng Mi > Signed-off-by: Dapeng Mi Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261021050711.4043= 703-1-dapeng1.mi@linux.intel.com?part=3D2