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=1793818620; b=X9Djeh06yYioyH1RfLUzDqLHB1pg1L0EUY62pQcqrh1OVJlSvB6wFyS0Icy7dt5w4+uo jpz5fyZmn9yvkPqFli1Kxi2XCjV/eeCCJaNNXk6iP69lJCxw+2cvr+TwmKg++EsZlaDW9 fsgyiWsFl/HhaKU0maCnvIv/UxC42h7bSH67hygT5ACHKIMf6GbO57gzzWNiFk972Kbyw ETXwKUxFmjd28e9yt9865sQ5z+NU4kFQdGCAgk8w9NQ0AZBB9vLEm7FPagHiC21x3qPmQ oBPv1vxdt41YLDxtR1vrfK9jMW7FMB+wSBdRu4dDrpbMVhgFNTCLpGOVJRzSn8hitIg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793818620; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=whbehQ7fFiWa/uL9ViBd+pafTrQYUqPHQQxoVjyW650=; b=OPXvfoRo0LhiU9htylf/OXA5/hq+v9Pdc77lrZJ7zMOngqsXl6IGQAxNU5pztvOryTF3 ePHxJcQgfd2Srd9iGawIKh5jlKC3QbnF7dA7fZ9UZzSQielNqCsQo4NEfX/fexYvIpGdE 6ctCEqd6cBY5wMB0/s5Nq93GxL+axCT4ONxW2zxoWViGr3dy/j621PU0DdR+eg2P0NJ/X zXs61cZCiZfoo5QWdD2ToAK/AmVCDsvExolcqR/sr4CcUjLimC9W5lL9NWqlqNPD5g6Qo tvN4SJfwlw8yk+6rXqOScM9z4sg61ddzmtOFE9kym7uCA0x7elcWSEwOf0VV9ThqmoA== 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=YKLXl0bc; 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 AB2D2606D804 for ; Wed, 4 Nov 2026 18:56:59 +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=YKLXl0bc Received: by smtp.kernel.org (Postfix) with ESMTPSA id 461C71F00A2C; Wed, 4 Nov 2026 18:56:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793818619; bh=whbehQ7fFiWa/uL9ViBd+pafTrQYUqPHQQxoVjyW650=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=YKLXl0bcsJU0yQ2kRvO6bcab9/RbYW99wB6LH4AhZcO+ukRwVwJzHBCVId/nx9fUX m6R9VNC9yyc4RZCZ1VoUbolQNJJ803gD+gCACUt3g5sBdsUNRlqjsrNxvJaUthI0W7 wAaw+f+SbPlpKH4pbfM9kVrRkIBmQckjy6UIASroWpjIUXMFF3/SR4WS46UsM97joa HTB7zrPSE4zmyFOXXlWFWPVHO28PQQcD22kHfgysoxUjTMmxgoZ45ANJILeV0lJlnU Fs0CmQJ70S5Z6ObdG78kvf5vhl6GKvh0vnC8JyI9SyvyIntLApw3uhD150DKidiot7 lzRX6Zq3QiDIA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v6 04/13] 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: <20261104-alpha-profileme-v6-4-63362e9290a3@gmail.com> References: <20261104-alpha-profileme-v6-0-63362e9290a3@gmail.com> <20261104-alpha-profileme-v6-4-63362e9290a3@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 04 Nov 2026 18:56:58 +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/20261104-alpha-prof= ileme-v6-0-63362e9290a3@gmail.com?part=3D4