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 AF20FC4332F for ; Wed, 2 Nov 2022 03:23:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230292AbiKBDXx (ORCPT ); Tue, 1 Nov 2022 23:23:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230312AbiKBDXw (ORCPT ); Tue, 1 Nov 2022 23:23:52 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1B3724BCE for ; Tue, 1 Nov 2022 20:23:51 -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 ams.source.kernel.org (Postfix) with ESMTPS id E806EB82055 for ; Wed, 2 Nov 2022 03:23:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D41D2C433C1; Wed, 2 Nov 2022 03:23:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667359428; bh=uAlIgFIYkVfiPxFBsebkHCz3eMrvjhj0B2NfboG9yEk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U00kTJ+fN3Qde+lqtVLwL8G4T2Lw0T7WsEVlPNttgkke8HLjXBlM0X6y3SVlQoDMC +JbXN/gsgpQ3okAgv4j+/liJmbh2bmS92G2FBmcyvTEEfR4wkuBKhwgO3sc8Hszrdj XO8ZPiYnfCvZHs96XVL1PoTV1t7XrmS2ePv88urI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chen Zhongjin , Josh Poimboeuf , Peter Zijlstra , Sasha Levin Subject: [PATCH 5.4 37/64] x86/unwind/orc: Fix unreliable stack dump with gcov Date: Wed, 2 Nov 2022 03:34:03 +0100 Message-Id: <20221102022053.018053491@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221102022051.821538553@linuxfoundation.org> References: <20221102022051.821538553@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Chen Zhongjin [ Upstream commit 230db82413c091bc16acee72650f48d419cebe49 ] When a console stack dump is initiated with CONFIG_GCOV_PROFILE_ALL enabled, show_trace_log_lvl() gets out of sync with the ORC unwinder, causing the stack trace to show all text addresses as unreliable: # echo l > /proc/sysrq-trigger [ 477.521031] sysrq: Show backtrace of all active CPUs [ 477.523813] NMI backtrace for cpu 0 [ 477.524492] CPU: 0 PID: 1021 Comm: bash Not tainted 6.0.0 #65 [ 477.525295] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-1.fc36 04/01/2014 [ 477.526439] Call Trace: [ 477.526854] [ 477.527216] ? dump_stack_lvl+0xc7/0x114 [ 477.527801] ? dump_stack+0x13/0x1f [ 477.528331] ? nmi_cpu_backtrace.cold+0xb5/0x10d [ 477.528998] ? lapic_can_unplug_cpu+0xa0/0xa0 [ 477.529641] ? nmi_trigger_cpumask_backtrace+0x16a/0x1f0 [ 477.530393] ? arch_trigger_cpumask_backtrace+0x1d/0x30 [ 477.531136] ? sysrq_handle_showallcpus+0x1b/0x30 [ 477.531818] ? __handle_sysrq.cold+0x4e/0x1ae [ 477.532451] ? write_sysrq_trigger+0x63/0x80 [ 477.533080] ? proc_reg_write+0x92/0x110 [ 477.533663] ? vfs_write+0x174/0x530 [ 477.534265] ? handle_mm_fault+0x16f/0x500 [ 477.534940] ? ksys_write+0x7b/0x170 [ 477.535543] ? __x64_sys_write+0x1d/0x30 [ 477.536191] ? do_syscall_64+0x6b/0x100 [ 477.536809] ? entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 477.537609] This happens when the compiled code for show_stack() has a single word on the stack, and doesn't use a tail call to show_stack_log_lvl(). (CONFIG_GCOV_PROFILE_ALL=y is the only known case of this.) Then the __unwind_start() skip logic hits an off-by-one bug and fails to unwind all the way to the intended starting frame. Fix it by reverting the following commit: f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks") The original justification for that commit no longer exists. That original issue was later fixed in a different way, with the following commit: f2ac57a4c49d ("x86/unwind/orc: Fix inactive tasks with stack pointer in %sp on GCC 10 compiled kernels") Fixes: f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks") Signed-off-by: Chen Zhongjin [jpoimboe: rewrite commit log] Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra Signed-off-by: Sasha Levin --- arch/x86/kernel/unwind_orc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c index 4e7c49fcf003..c85634152d30 100644 --- a/arch/x86/kernel/unwind_orc.c +++ b/arch/x86/kernel/unwind_orc.c @@ -687,7 +687,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task, /* Otherwise, skip ahead to the user-specified starting frame: */ while (!unwind_done(state) && (!on_stack(&state->stack_info, first_frame, sizeof(long)) || - state->sp < (unsigned long)first_frame)) + state->sp <= (unsigned long)first_frame)) unwind_next_frame(state); return; -- 2.35.1