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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 F13B3ECDE5F for ; Thu, 19 Jul 2018 14:52:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B5C4020673 for ; Thu, 19 Jul 2018 14:52:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B5C4020673 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731837AbeGSPgU (ORCPT ); Thu, 19 Jul 2018 11:36:20 -0400 Received: from terminus.zytor.com ([198.137.202.136]:51263 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727575AbeGSPgU (ORCPT ); Thu, 19 Jul 2018 11:36:20 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w6JEpqg62318915 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Thu, 19 Jul 2018 07:51:52 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w6JEppS12318909; Thu, 19 Jul 2018 07:51:51 -0700 Date: Thu, 19 Jul 2018 07:51:51 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Rasmus Villemoes Message-ID: Cc: torvalds@linux-foundation.org, jpoimboe@redhat.com, mingo@kernel.org, hpa@zytor.com, linux@rasmusvillemoes.dk, penguin-kernel@I-love.SAKURA.ne.jp, luto@amacapital.net, peterz@infradead.org, linux-kernel@vger.kernel.org, bp@suse.de, tglx@linutronix.de Reply-To: torvalds@linux-foundation.org, mingo@kernel.org, jpoimboe@redhat.com, linux@rasmusvillemoes.dk, hpa@zytor.com, luto@amacapital.net, penguin-kernel@I-love.SAKURA.ne.jp, peterz@infradead.org, linux-kernel@vger.kernel.org, bp@suse.de, tglx@linutronix.de In-Reply-To: <1532009278-5953-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> References: <1532009278-5953-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/debug] x86: Avoid pr_cont() in show_opcodes() Git-Commit-ID: 8e974b3b8eddd42a8c43a18e8ea66a3e7b803a0d X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 8e974b3b8eddd42a8c43a18e8ea66a3e7b803a0d Gitweb: https://git.kernel.org/tip/8e974b3b8eddd42a8c43a18e8ea66a3e7b803a0d Author: Rasmus Villemoes AuthorDate: Thu, 19 Jul 2018 23:07:58 +0900 Committer: Thomas Gleixner CommitDate: Thu, 19 Jul 2018 16:46:23 +0200 x86: Avoid pr_cont() in show_opcodes() If concurrent printk() messages are emitted, then pr_cont() is making it extremly hard to decode which part of the output belongs to what. See the convoluted example at: https://syzkaller.appspot.com/text?tag=CrashReport&x=139d342c400000 Avoid this by using a proper prefix for each line and by using %ph format in show_opcodes() which emits the 'Code:' line in one go. Signed-off-by: Rasmus Villemoes Signed-off-by: Tetsuo Handa Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Cc: joe@perches.com Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Josh Poimboeuf Cc: Linus Torvalds Link: https://lkml.kernel.org/r/1532009278-5953-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp --- arch/x86/kernel/dumpstack.c | 28 +++++++++------------------- 1 file changed, 9 insertions(+), 19 deletions(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 666a284116ac..9c8652974f8e 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -22,8 +22,6 @@ #include #include -#define OPCODE_BUFSIZE 64 - int panic_on_unrecovered_nmi; int panic_on_io_nmi; static int die_counter; @@ -93,26 +91,18 @@ static void printk_stack_address(unsigned long address, int reliable, */ void show_opcodes(u8 *rip, const char *loglvl) { - unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3; +#define PROLOGUE_SIZE 42 +#define EPILOGUE_SIZE 21 +#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE) u8 opcodes[OPCODE_BUFSIZE]; - u8 *ip; - int i; - - printk("%sCode: ", loglvl); - - ip = (u8 *)rip - code_prologue; - if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) { - pr_cont("Bad RIP value.\n"); - return; - } - for (i = 0; i < OPCODE_BUFSIZE; i++, ip++) { - if (ip == rip) - pr_cont("<%02x> ", opcodes[i]); - else - pr_cont("%02x ", opcodes[i]); + if (probe_kernel_read(opcodes, rip - PROLOGUE_SIZE, OPCODE_BUFSIZE)) { + printk("%sCode: Bad RIP value.\n", loglvl); + } else { + printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %" + __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes, + opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1); } - pr_cont("\n"); } void show_ip(struct pt_regs *regs, const char *loglvl)