From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1BEF837A82E; Wed, 7 Oct 2026 18:19:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791397188; cv=none; b=F3sl1JEQvPqFJX1msRg36G3E+mfKaCWDESJ7hg86PV/N3NZCrk8BzKzba6r+JCn380gsmgqkMY+Bfrol1xlJpx7t63slb80vSpr/mySZSJdhAo3Q/VQL4I+wLqy99DreOaNUadQi02MCSrXYyr3Nr0ZPHW2gKuevYAKag3v/wMo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791397188; c=relaxed/simple; bh=mQWLG8EcUn9rp3N8qH/PyrT7D1WSn40KsnAxp4I24DQ=; h=Message-ID:From:Subject:To:Cc:In-Reply-To:References:Content-Type: Date; b=E6xVge9lOV1hzXX6e+KGDEdLp2tzTWjhUbpW+ipa5QX04RfneIBc/rwf7+Q2Zv/fUxISFgZJ6o7qytqJ9knJ/TxYFOyunKtqWv3bcVSdLr8HohBy7KHzG2vDrQOeOuW5u4YDQKtA25kbiQgdjKRJM/qJK0puQc1m1Q/JMy/f8V4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=he5EXmwG; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="he5EXmwG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 009C51F000FF; Wed, 7 Oct 2026 18:19:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791397177; bh=mQWLG8EcUn9rp3N8qH/PyrT7D1WSn40KsnAxp4I24DQ=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=he5EXmwGY4Ogbz8AYsCS9+zEHVFO6C2V8BcmzgPUrJNY5YRW3VoscHkdbnWWmhNyO yKAe+MniyprGYfnUE5gPwHlXc7Wvi2AEpw76nPm4jGJUdpsmCZYANuxQ9IjB6Jc//u 84Qk5HwMnUkIRqwScRiuBb+whh3hW7aBMpJJ4QOd7lnf5+bK3RSYk3m/Qe6RRs8pFd TmRiWqu1LJfsDjO93HgljeWOSVRU+jp+oiS6Gwte4xIskJD8PLaH3WmTe26x7ubhfi uMeLEx8BXLeG1eIqm+UGu1u/XlG1WdUNgqxVDqgfvz1BG5N1KZrDyUnwarKZ7hreQ1 pcCYpf8ZyW6Hw== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH] perf/x86/amd/lbr: Limit branch snapshots to valid entries Reply-To: sashiko-reviews@lists.linux.dev To: "Sandipan Das" Cc: linux-perf-users@vger.kernel.org, bpf@vger.kernel.org In-Reply-To: <20261007181002.4005262-1-sandipan.das@amd.com> References: <20261007181002.4005262-1-sandipan.das@amd.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 07 Oct 2026 18:19:36 +0000 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > 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 Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261007181002.4005= 262-1-sandipan.das@amd.com?part=3D1