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[2620:137:e000::1:20]) by mx.google.com with ESMTP id t6-20020a056402524600b0045a5bd66302si23302435edd.571.2022.10.21.13.18.48; Fri, 21 Oct 2022 13:19:16 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linutronix.de header.s=2020 header.b=G6Ofe4e6; dkim=neutral (no key) header.i=@linutronix.de header.b=jcLVAxS3; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=linutronix.de Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230202AbiJUUQ4 (ORCPT + 99 others); Fri, 21 Oct 2022 16:16:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229776AbiJUUQy (ORCPT ); Fri, 21 Oct 2022 16:16:54 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A2F329E5A0; Fri, 21 Oct 2022 13:16:52 -0700 (PDT) Date: Fri, 21 Oct 2022 20:16:48 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1666383410; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=rL3oVgJETn6O3bWX+jYbwettXNPsuf0/KLBlpRfdKuE=; b=G6Ofe4e6tD9SxU/71931ZAZDTZV+6Mhp+qlH8PVmta9/th+zFdLai0I9J2x9BbBwCogiw3 B8Lff1+vm5oUt1mLynEbJu7AQybbmb6O+2R/3xvd3e2SE9GM00qwOpx5Lbkn7sDm402DIO yROQMzupcP/rdCKl3Ev4jPWgdEevbe5SL6AgS3Jn8+nWJ2WYBxpwNLNQeuKK6uobwAQ3I4 rQIAX5uNWuDNT9IgeNrPdPZ3lw+FYIfQpmy0FKp3/5XUuxtaeeUJQZ3UO+IRfAcoZ93osm nf9RoFHbRAH5xc1JHw5s8K1pfbsEwUSDaCKeMVhSkVrvQaW+DntPS+NnMH7USg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1666383410; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=rL3oVgJETn6O3bWX+jYbwettXNPsuf0/KLBlpRfdKuE=; b=jcLVAxS35afWjaCEppXqwCwEbcMTTjDaZf2DfNJOhgauV6ImL/kUor/TX8CGwYswMkdc7J URj49hczmkOYEwDw== From: "tip-bot2 for Chen Zhongjin" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: objtool/urgent] x86/unwind/orc: Fix unreliable stack dump with gcov Cc: Chen Zhongjin , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org MIME-Version: 1.0 Message-ID: <166638340876.401.7064883651633264359.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1747329803870984991?= X-GMAIL-MSGID: =?utf-8?q?1747329803870984991?= The following commit has been merged into the objtool/urgent branch of tip: Commit-ID: 230db82413c091bc16acee72650f48d419cebe49 Gitweb: https://git.kernel.org/tip/230db82413c091bc16acee72650f48d419cebe49 Author: Chen Zhongjin AuthorDate: Wed, 27 Jul 2022 11:15:06 +08:00 Committer: Peter Zijlstra CommitterDate: Fri, 21 Oct 2022 14:56:42 +02:00 x86/unwind/orc: Fix unreliable stack dump with gcov 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 --- 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 0ea57da..c059820 100644 --- a/arch/x86/kernel/unwind_orc.c +++ b/arch/x86/kernel/unwind_orc.c @@ -713,7 +713,7 @@ 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;