From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 416ABC4332F for ; Mon, 28 Mar 2022 11:37:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242130AbiC1LeG (ORCPT ); Mon, 28 Mar 2022 07:34:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46270 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241063AbiC1L0I (ORCPT ); Mon, 28 Mar 2022 07:26:08 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 662D363A7; Mon, 28 Mar 2022 04:23:43 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 27251611BD; Mon, 28 Mar 2022 11:23:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96911C340EC; Mon, 28 Mar 2022 11:23:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648466613; bh=dXFoBao1mnO+CxBybDVWep7qs/QLa3ksJJVYsnYonhc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QJY9h7NJBZ3qNcYytwEmg6Ux8YnKKrfNEuuJTSgaM5fDic9YBJHYDjghQtGXaPXZp fBMulYM3DCpHnl2Pm2EVHycZTQBl0/UiD5z885Htnrke1WxQ6TQgpr7eesQZb5USQO 5+VQ2SwT2lCukZGC1/8vJ0Gv4d7l7eqmWeR0hMFIfrc/2qYI7bWonXtJWTuMK14mVU tcMYpXxeHmzPCWgkn8XO5/FQBRhYNlgTlbQkFSUupEpKrX6yB+/zgR2NUzLuutSh3l T6cdiYpd2PKD33p9GylfLX9qGq1tFOnZDH8qEt9c/cU0lp8n3ZCUKsv3HTp3x96JZm UZio3sWauiBJQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Darren Hart , "Rafael J . Wysocki" , Sasha Levin , rafael@kernel.org, rdunlap@infradead.org, ying.huang@intel.com, linux-acpi@vger.kernel.org Subject: [PATCH AUTOSEL 5.10 17/21] ACPI/APEI: Limit printable size of BERT table data Date: Mon, 28 Mar 2022 07:22:50 -0400 Message-Id: <20220328112254.1556286-17-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220328112254.1556286-1-sashal@kernel.org> References: <20220328112254.1556286-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Darren Hart [ Upstream commit 3f8dec116210ca649163574ed5f8df1e3b837d07 ] Platforms with large BERT table data can trigger soft lockup errors while attempting to print the entire BERT table data to the console at boot: watchdog: BUG: soft lockup - CPU#160 stuck for 23s! [swapper/0:1] Observed on Ampere Altra systems with a single BERT record of ~250KB. The original bert driver appears to have assumed relatively small table data. Since it is impractical to reassemble large table data from interwoven console messages, and the table data is available in /sys/firmware/acpi/tables/data/BERT limit the size for tables printed to the console to 1024 (for no reason other than it seemed like a good place to kick off the discussion, would appreciate feedback from existing users in terms of what size would maintain their current usage model). Alternatively, we could make printing a CONFIG option, use the bert_disable boot arg (or something similar), or use a debug log level. However, all those solutions require extra steps or change the existing behavior for small table data. Limiting the size preserves existing behavior on existing platforms with small table data, and eliminates the soft lockups for platforms with large table data, while still making it available. Signed-off-by: Darren Hart Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- drivers/acpi/apei/bert.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/apei/bert.c b/drivers/acpi/apei/bert.c index 19e50fcbf4d6..ad8ab3f12cf3 100644 --- a/drivers/acpi/apei/bert.c +++ b/drivers/acpi/apei/bert.c @@ -29,6 +29,7 @@ #undef pr_fmt #define pr_fmt(fmt) "BERT: " fmt +#define ACPI_BERT_PRINT_MAX_LEN 1024 static int bert_disable; @@ -58,8 +59,11 @@ static void __init bert_print_all(struct acpi_bert_region *region, } pr_info_once("Error records from previous boot:\n"); - - cper_estatus_print(KERN_INFO HW_ERR, estatus); + if (region_len < ACPI_BERT_PRINT_MAX_LEN) + cper_estatus_print(KERN_INFO HW_ERR, estatus); + else + pr_info_once("Max print length exceeded, table data is available at:\n" + "/sys/firmware/acpi/tables/data/BERT"); /* * Because the boot error source is "one-time polled" type, -- 2.34.1