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=1793940401; b=VMKWzDGgPjQNPQfWQpMiHYHvXsh6nScW45s3Vjma+UEqdLhfY+oTrG2Ra0FXmFhffS5j n6wN6rvZDfE9thrKKqwE+xQaVkxd5CISh+oACWtJqn3ASvwP6Xl893+XAZLbapTvhHq8B 5Pu8dU9rHP9ldQuTbHt4bPkcLazKTLhYTqnTzxMWMzRH1w2I1vuPBfldQFcQyy2ZckEkM Jr4ba2DX97mCcCIt26EUNyy4zh89GaTvnyJrssEjd7iHCr+CHqygkBRDigRq9//X+m8pe yd/4fG79uFWdu7LBKcDtlHZNwJOf1aMooSw2Z6XsPLOEcJOvcpMsCjkZnDxFJq89P2w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793940401; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=TeSJUipgE/47PHtJXpheCvT+FY6w2Zv5/CK6qVoMfbY=; b=OdVzU50gTq2AaFhbZcuRowbaKm/QZo/Mdz2tYoYWmGmPgFfLAfWrYJKgGTdDQCKXstyv QT5/7hUClzWd+Aa515sL74l/KVdnuMTJsR1n/nBZ8DZel6cfcTQsHnq752Z88BQQ4mzSv X6Lv8oxHCbnenLGVmONA8oQ66nyApj2C7bIxcON3ptR/uKxg92jFqTVGv9EWZ1G0k/ZIQ tcx6mCrMynO7kWi+j98CADXcn7kxbjI5skY9g/wbAPXWHfc1ggrCRdIZZIuBudSgk1gmi Rs2TWMLVt6BDHTOCo5K3R3vcnpuvsDwtM0HBCRz9NCelhAei2z4RDqropY4qW2O7HSQ== 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=Gi9wUdj9; 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 CDE40606A326 for ; Fri, 6 Nov 2026 04:46:40 +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=Gi9wUdj9 Received: by smtp.kernel.org (Postfix) with ESMTPSA id CEA8E1F0089F; Fri, 6 Nov 2026 04:46:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793940400; bh=TeSJUipgE/47PHtJXpheCvT+FY6w2Zv5/CK6qVoMfbY=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=Gi9wUdj9P16tFsuk8qmVR3TeWYau3KbGGoLjwK4r0VHu0sa/cXk9J2d9vos7fbxnr IRfUsDdB335OyGBfBzOXeAxBynWv6Hn9TaexyFS+JaWPTI/3U98KtmyjRPE6Tqyb+w 02zkPEOOkFk+uUNfeGz+IH4MR6/LzwPWyF2B+BHb2z66La5jKZzeRMr+l//NsqdsKv RZlJ5ygkOBqWQmk2cA1BejRehYZoHEMA1rkGLdjpibdQgp5+akL6ERkYyo0+WQP4KX pManku2kHGI5pjeQa/N7yHyIAtGzMEoNgY7ncT8mmudtzge97Qk77IgJr9q4lqicmp EisBQDaHD+yGQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v7 05/14] 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: <20261105-alpha-profileme-v7-5-c474e892abb0@gmail.com> References: <20261105-alpha-profileme-v7-0-c474e892abb0@gmail.com> <20261105-alpha-profileme-v7-5-c474e892abb0@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Fri, 06 Nov 2026 04:46:39 +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/20261105-alpha-prof= ileme-v7-0-c474e892abb0@gmail.com?part=3D5