From patchwork Thu Jan 18 15:25:11 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nathan Lynch via B4 Relay X-Patchwork-Id: 1888120 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=EikAJD1G; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=112.213.38.117; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org; receiver=patchwork.ozlabs.org) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4TG6BN5ncPz1yPv for ; Fri, 19 Jan 2024 02:30:04 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=EikAJD1G; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4TG6BN4mtvz3c75 for ; Fri, 19 Jan 2024 02:30:04 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=EikAJD1G; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=145.40.68.75; helo=ams.source.kernel.org; envelope-from=devnull+nathanl.linux.ibm.com@kernel.org; receiver=lists.ozlabs.org) Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4TG65Q44NWz3bqx for ; Fri, 19 Jan 2024 02:25:46 +1100 (AEDT) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id AAA83B818E9; Thu, 18 Jan 2024 15:25:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPS id 0DB1EC433C7; Thu, 18 Jan 2024 15:25:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1705591542; bh=ZrNZI/+KtaqDAeKBFPjQTAb311LBOoljbtl1LqlVqgU=; h=From:Subject:Date:To:Cc:Reply-To:From; b=EikAJD1G0pb3jVcwCRG+fB0VgJ6aECiR0DbO54vwJS46/PkKZ7ypAmiMAywBa+7JN C1OngJTsht/5e51HRbViv6HUrlVtjUPRv0J3Qk7C2KjRCLiFQz0JvjuGslWHyND9md f0XkLLJ4PU0msMmmK7luaFGXqzi9hMuWLJp3wG8GINIkNCqsC+XfxzRa/E9Q94Cyff gfZdmoS1nRFjp1cnjYAQndurEZBfwEKhUM9cdi+42IQxFdV6CMds4/EpKOcop3BAPf 3UaFtN62BBsJQ2ySVDbcgHKrVeyIn30mRyuKzVlplAmvtbTAq8M2jafdjw0NKeMuEo eXCfOwb6+Tr4A== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0019C4707B; Thu, 18 Jan 2024 15:25:41 +0000 (UTC) From: Nathan Lynch via B4 Relay Subject: [PATCH RFC 0/5] dump_stack: Allow runtime updates of the hardware description Date: Thu, 18 Jan 2024 09:25:11 -0600 Message-Id: <20240118-update-dump-stack-arch-str-v1-0-5c0f98d017b5@linux.ibm.com> MIME-Version: 1.0 X-B4-Tracking: v=1; b=H4sIANdCqWUC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyDHUUlJIzE vPSU3UzU4B8JSMDIxMDQ0ND3dKClMSSVN2U0twC3eKSxORs3cSi5Awgs0jXPM3AwsIgxcg4zdh ACWhAQVFqWmYF2PBopSA3Z6XY2loA6bwz0HEAAAA= To: "Aneesh Kumar K.V" , "Naveen N. Rao" , Brian King , Christophe Leroy , John Ogness , Michael Ellerman , Nicholas Piggin , Petr Mladek , Sergey Senozhatsky , Steven Rostedt X-Mailer: b4 0.12.4 X-Developer-Signature: v=1; a=ed25519-sha256; t=1705591541; l=2778; i=nathanl@linux.ibm.com; s=20230817; h=from:subject:message-id; bh=ZrNZI/+KtaqDAeKBFPjQTAb311LBOoljbtl1LqlVqgU=; b=vrcF1cNPIm2O4+bieSkcw1uoqBBdSqf4JkN+kVqZt0fSLkeqYShpMyznUhC+rjw1sJEeTCg3r HvE7JadRlXGBBcZSgBWO/h+xHLaE9TtJfvuE3gqdy++muQ22sED6j1/ X-Developer-Key: i=nathanl@linux.ibm.com; a=ed25519; pk=jPDF44RvT+9DGFOH3NGoIu1xN9dF+82pjdpnKjXfoJ0= X-Endpoint-Received: by B4 Relay for nathanl@linux.ibm.com/20230817 with auth_id=78 X-Original-From: Nathan Lynch X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: nathanl@linux.ibm.com Cc: Nathan Lynch , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" When the kernel emits a stack trace, typically it includes a hardware description string, e.g. Kernel panic - not syncing: sysrq triggered crash CPU: 6 PID: 46433 Comm: bash Tainted: G W 6.7.0-rc2+ #83 > Hardware name: IBM,9040-MR9 POWER9 (architected) 0x4e2102 0xf000005 of:IBM,FW950.01 (VM950_047) hv:phyp pSeries Call Trace: dump_stack_lvl+0xc4/0x170 (unreliable) panic+0x39c/0x584 sysrq_handle_crash+0x80/0xe0 __handle_sysrq+0x208/0x4bc [...] This string is a statically allocated buffer populated during boot by arch code calling dump_stack_set_arch_desc(). For most platforms this is sufficient. But the string may become inaccurate on the IBM PowerVM platform due to live migration between machine models and firmware versions. Stack dumps emitted after a migration reflect the machine on which the kernel booted, not necessarily the machine on which it is currently running. This is potentially confusing for anyone investigating kernel issues on the platform. To address this, this series introduces a new function that safely updates the hardware description string and updates the powerpc pseries platform code to call it after a migration. The series also includes changes addressing minor latent issues identified during the implementation. Platforms which do not need the new functionality remain unchanged. For this initial version at least, the powerpc/pseries part includes some "self-test" code that 1. verifies that reconstructing the hardware description string late in boot matches the one that was built earlier, and 2. fully exercises the update path before any migrations occur. This could be dropped or made configurable in the future. Signed-off-by: Nathan Lynch --- Nathan Lynch (5): dump_stack: Make arch description buffer __ro_after_init dump_stack: Allow update of arch description string at runtime powerpc/prom: Add CPU info to hardware description string later powerpc/pseries: Prepare pseries_add_hw_description() for runtime use powerpc/pseries: Update hardware description string after migration arch/powerpc/kernel/prom.c | 12 +++-- arch/powerpc/platforms/pseries/mobility.c | 5 ++ arch/powerpc/platforms/pseries/pseries.h | 1 + arch/powerpc/platforms/pseries/setup.c | 80 +++++++++++++++++++++++++++++-- include/linux/printk.h | 5 ++ lib/dump_stack.c | 57 ++++++++++++++++++++-- 6 files changed, 146 insertions(+), 14 deletions(-) --- base-commit: 44a1aad2fe6c10bfe0589d8047057b10a4c18a19 change-id: 20240111-update-dump-stack-arch-str-7f0880d23f30 Best regards,