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=1793738766; b=QynV9Acb7KAmTgxF6bsWWl8aDPKjSYBJOW5QGgyacYMMQFgWMrQhPdssiC/nKbE+MC42 rJS1iCLF7bwthBOrTwDBZ8iPJf1ZCW3hx3mMsm7kLORKgM/Es+Je72LEHoI6FccKJyz9K 4bQyX6U1wbLQPVtMuYWWSuK78cdGJjMRZDCULLqbpqFV0MY+wJ8Hod2ew4lhK3nr7jGPa gZAhOn7NcKnpnthqqloL+hpiXN1mzA66HgsD1SiwUe9PF868bflmfewLktDjVBFrTMieC OK7rqumXIziQbfvXtJetZlRXDg59ka76ljAOtsVmKFEqyoYco1PgPa5pBvxB4gg2ung== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793738766; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=9M7iCnvJB/hrBg6FIghxOu5pxby9gl/eYcNgJFVOwrc=; b=Nlhn6bUFX7QVvWLXpzLyl0pP/qRQ1zW5BSw/fk134HxTxGFVjLguhFjdBjrfIuGt5QHa lp0rA51xK+1C2jh94bY3sIEttbUE2gZjdJKn+O1Yw0wv6n1MVOAamR69d/jsdeiacpCIv qJhr0pyTxaMHgjc++nihYx+Wz7bGfo0q+1MzPH7sw8tbK5YE2gAPswvivvd1up2UNJvuW WF4VggVlXfjmpGpbdZ8nZ0jZkhINteXeweAukxoREnfcICgg2uGmjW2gGoweX8kG9STNo 2O5zFN+arGrY2LBOtjl73aP37cDcQ8iytVil3uMWTZTARpEDHqgREkjUfxyXIMjDxpw== 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=bd6VcQh2; 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 8DCD8606A31B for ; Tue, 3 Nov 2026 20:46:06 +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=bd6VcQh2 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4FB811F000C1; Tue, 3 Nov 2026 20:46:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793738766; bh=9M7iCnvJB/hrBg6FIghxOu5pxby9gl/eYcNgJFVOwrc=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=bd6VcQh2a9G/Ka5kHcEjwgs4nAkU/7fOm2CZ2xWbr40/W9vSWyM3QfqJg35IBs/5j 7pvzdTgvNpoYUitmPVOoSidSSaHlFr0Du0i5HR7N3qr3Jmv0/fNXxn+Uf2LQpkfA9w G6Igt5tCvimvGinJlPV8QvWv134j15/0EZ5RI27XU//K0EK3WIS1K82bWeR7lm5y1m SNjWuvWXYzrnYRwViwvTC6ntWEj95azhI6a+MXjUnzVPmiag+FuBAU+5Mi5TbgD2WH lpZWksjgRlIwxvdVZrr8LjgPgDp3OO+9b1j9rBro6cD2O4xaFFoJy/u7zgPcoNQrTC a1paM9SudnN+Q== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v5 04/11] alpha/perf: do not report user registers from the entry code Reply-To: sashiko-reviews@lists.linux.dev To: "Matt Turner" Cc: linux-perf-users@vger.kernel.org In-Reply-To: <20261103-alpha-profileme-v5-4-bbe3937fbf3a@gmail.com> References: <20261103-alpha-profileme-v5-0-bbe3937fbf3a@gmail.com> <20261103-alpha-profileme-v5-4-bbe3937fbf3a@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 03 Nov 2026 20:46:05 +0000 X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > perf_get_regs_user() returns task_pt_regs() whenever a sample of a user > task lands in the kernel. But exception entry runs with interrupts > enabled, so the sample can land before the entry code has saved the user > registers. Only the part PALcode pushed is valid then. An interrupt > taken on the first instruction of entUna, say, pushes its own frame on > top of PALcode's, which overlaps the rest of the user frame, so r7 and r8 > read as the interrupt's r23 and r24. >=20 > Report no user registers while the interrupted PC is in the entry code. > Such a sample also gets no user stack dump. The range is all of the entry > code from entInt to the end of the save in entSys, so it also drops the > registers of samples that land after they were saved there. >=20 > An interrupt that nests on one taken in the entry code still reads the > incomplete frame, as its own PC has left the entry code. >=20 > Fixes: 9280e99d87dd ("alpha: add HAVE_PERF_REGS and HAVE_PERF_USER_STACK_= DUMP support") > Assisted-by: Claude:claude-opus-5-5 > Reviewed-by: Magnus Lindholm > Tested-by: Magnus Lindholm > Signed-off-by: Matt Turner Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261103-alpha-prof= ileme-v5-0-bbe3937fbf3a@gmail.com?part=3D4