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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 33118C433E0 for ; Tue, 9 Jun 2020 00:29:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EEAB2078B for ; Tue, 9 Jun 2020 00:29:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591662552; bh=RfxFKmhgcRkNvGD3wM7B5OoR3tKuCY7MGRl46QgFn9o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=xyMC6mgekSSRo/A6lq/WhdojlxiQyhLBcOugva3FNjb0Plo1SIuAuWc4G12LCbiby qEjEItxOBsmGUcN5Vucx/J2jw+OSjWJv2S/2bLkZBC01UV8B5Zugs4Q60uwuJVMprY EyRqUzhRXDoD7es51Ud2GNKtYZvee5+Sh0fhZeeY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387726AbgFIA3K (ORCPT ); Mon, 8 Jun 2020 20:29:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:37514 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730191AbgFHXQN (ORCPT ); Mon, 8 Jun 2020 19:16:13 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4139920823; Mon, 8 Jun 2020 23:16:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591658172; bh=RfxFKmhgcRkNvGD3wM7B5OoR3tKuCY7MGRl46QgFn9o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IXp3jO3EmyvQiUhEoU2xKvj94o7fpn2tCLM3xnQzEF82EPAHnIZSCnZhENsyTBJ1s bqJ46zEtT1sBH8kO/ze6iqR1ah/0iUBHxnnifbV9MA3H1H2wnBYcXsepT9YdsaLCiF cbAt/CGTSDPcT1+r6oa/vGaN2FFIOQDGS4bn+DBs= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Josh Poimboeuf , Tetsuo Handa , Peter Zijlstra , Greg Kroah-Hartman Subject: [PATCH AUTOSEL 5.6 199/606] x86/unwind/orc: Fix unwind_get_return_address_ptr() for inactive tasks Date: Mon, 8 Jun 2020 19:05:24 -0400 Message-Id: <20200608231211.3363633-199-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200608231211.3363633-1-sashal@kernel.org> References: <20200608231211.3363633-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Josh Poimboeuf commit 187b96db5ca79423618dfa29a05c438c34f9e1f0 upstream. Normally, show_trace_log_lvl() scans the stack, looking for text addresses to print. In parallel, it unwinds the stack with unwind_next_frame(). If the stack address matches the pointer returned by unwind_get_return_address_ptr() for the current frame, the text address is printed normally without a question mark. Otherwise it's considered a breadcrumb (potentially from a previous call path) and it's printed with a question mark to indicate that the address is unreliable and typically can be ignored. Since the following commit: f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks") ... for inactive tasks, show_trace_log_lvl() prints *only* unreliable addresses (prepended with '?'). That happens because, for the first frame of an inactive task, unwind_get_return_address_ptr() returns the wrong return address pointer: one word *below* the task stack pointer. show_trace_log_lvl() starts scanning at the stack pointer itself, so it never finds the first 'reliable' address, causing only guesses to being printed. The first frame of an inactive task isn't a normal stack frame. It's actually just an instance of 'struct inactive_task_frame' which is left behind by __switch_to_asm(). Now that this inactive frame is actually exposed to callers, fix unwind_get_return_address_ptr() to interpret it properly. Fixes: f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks") Reported-by: Tetsuo Handa Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200522135435.vbxs7umku5pyrdbk@treble Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/unwind_orc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c index 9414f02a55ea..1a90abeca5f3 100644 --- a/arch/x86/kernel/unwind_orc.c +++ b/arch/x86/kernel/unwind_orc.c @@ -314,12 +314,19 @@ EXPORT_SYMBOL_GPL(unwind_get_return_address); unsigned long *unwind_get_return_address_ptr(struct unwind_state *state) { + struct task_struct *task = state->task; + if (unwind_done(state)) return NULL; if (state->regs) return &state->regs->ip; + if (task != current && state->sp == task->thread.sp) { + struct inactive_task_frame *frame = (void *)task->thread.sp; + return &frame->ret_addr; + } + if (state->sp) return (unsigned long *)state->sp - 1; -- 2.25.1