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 X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E6D6C433B4 for ; Thu, 20 May 2021 09:26:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 20A926101E for ; Thu, 20 May 2021 09:26:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232087AbhETJ2A (ORCPT ); Thu, 20 May 2021 05:28:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:52818 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231872AbhETJ1H (ORCPT ); Thu, 20 May 2021 05:27:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4A5BB613B9; Thu, 20 May 2021 09:25:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621502746; bh=ZdzK8q4w+TKlcqaURXyQyLF5Sq2YRST6TcrOEl50yss=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Spy+dysOVV4G1f5DJ8YYX5q2RyrGGAtakO3QBpX1pTM2egrzhC/x5XdEcamrqZm86 TJ+7mM46+j6q1T5N4nPfRDi2jexqkXZxE5lIC1wNwCGY73W6y/bqonmYNUyvJpTYuS Zq2QVU0wGdO8x/MnhJ/CPJJYQwi6GCoKS+3B7ueg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "louis.wang" , Russell King , Sasha Levin Subject: [PATCH 5.12 09/45] ARM: 9066/1: ftrace: pause/unpause function graph tracer in cpu_suspend() Date: Thu, 20 May 2021 11:21:57 +0200 Message-Id: <20210520092053.822371348@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092053.516042993@linuxfoundation.org> References: <20210520092053.516042993@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: louis.wang [ Upstream commit 8252ca87c7a2111502ee13994956f8c309faad7f ] Enabling function_graph tracer on ARM causes kernel panic, because the function graph tracer updates the "return address" of a function in order to insert a trace callback on function exit, it saves the function's original return address in a return trace stack, but cpu_suspend() may not return through the normal return path. cpu_suspend() will resume directly via the cpu_resume path, but the return trace stack has been set-up by the subfunctions of cpu_suspend(), which makes the "return address" inconsistent with cpu_suspend(). This patch refers to Commit de818bd4522c40ea02a81b387d2fa86f989c9623 ("arm64: kernel: pause/unpause function graph tracer in cpu_suspend()"), fixes the issue by pausing/resuming the function graph tracer on the thread executing cpu_suspend(), so that the function graph tracer state is kept consistent across functions that enter power down states and never return by effectively disabling graph tracer while they are executing. Signed-off-by: louis.wang Signed-off-by: Russell King Signed-off-by: Sasha Levin --- arch/arm/kernel/suspend.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c index 24bd20564be7..43f0a3ebf390 100644 --- a/arch/arm/kernel/suspend.c +++ b/arch/arm/kernel/suspend.c @@ -1,4 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 +#include #include #include #include @@ -25,6 +26,13 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) if (!idmap_pgd) return -EINVAL; + /* + * Function graph tracer state gets incosistent when the kernel + * calls functions that never return (aka suspend finishers) hence + * disable graph tracing during their execution. + */ + pause_graph_tracing(); + /* * Provide a temporary page table with an identity mapping for * the MMU-enable code, required for resuming. On successful @@ -32,6 +40,9 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) * back to the correct page tables. */ ret = __cpu_suspend(arg, fn, __mpidr); + + unpause_graph_tracing(); + if (ret == 0) { cpu_switch_mm(mm->pgd, mm); local_flush_bp_all(); @@ -45,7 +56,13 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) { u32 __mpidr = cpu_logical_map(smp_processor_id()); - return __cpu_suspend(arg, fn, __mpidr); + int ret; + + pause_graph_tracing(); + ret = __cpu_suspend(arg, fn, __mpidr); + unpause_graph_tracing(); + + return ret; } #define idmap_pgd NULL #endif -- 2.30.2