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 2CBE5C4321E for ; Fri, 7 Sep 2018 13:47:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E42F32075E for ; Fri, 7 Sep 2018 13:47:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E42F32075E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=c-s.fr 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 S1729755AbeIGS2g (ORCPT ); Fri, 7 Sep 2018 14:28:36 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:11745 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729759AbeIGS2f (ORCPT ); Fri, 7 Sep 2018 14:28:35 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 426Jf81WqVz9ttFV; Fri, 7 Sep 2018 15:47:28 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id gvveKOW7ZczI; Fri, 7 Sep 2018 15:47:28 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 426Jf81275z9ttFK; Fri, 7 Sep 2018 15:47:28 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id CAA788B950; Fri, 7 Sep 2018 15:47:31 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id tih4xwaLPVHG; Fri, 7 Sep 2018 15:47:31 +0200 (CEST) Received: from pc16082vm.idsi0.si.c-s.fr (po15451.idsi0.si.c-s.fr [172.25.231.3]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 8E98E8B94C; Fri, 7 Sep 2018 15:47:31 +0200 (CEST) Received: by pc16082vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 88A41718AB; Fri, 7 Sep 2018 13:47:31 +0000 (UTC) Message-Id: <8f4de3aa04f00d67fdb5aaf90f41242197310d4d.1536327756.git.christophe.leroy@c-s.fr> In-Reply-To: <113d4a559f6eec448b253bf5f0b4f2a8ffb187af.1536327756.git.christophe.leroy@c-s.fr> References: <113d4a559f6eec448b253bf5f0b4f2a8ffb187af.1536327756.git.christophe.leroy@c-s.fr> From: Christophe Leroy Subject: [PATCH v3 2/3] powerpc/process: fix interleaved output in show_user_instructions() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , muriloo@linux.ibm.com Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Date: Fri, 7 Sep 2018 13:47:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When two processes crash at the same time, we sometimes encounter interleaving in the middle of a line: [ 4.365317] init[1]: segfault (11) at 0 nip 0 lr 0 code 1 [ 4.370452] init[1]: code: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX [ 4.372042] init[74]: segfault (11) at 10a74 nip 1000c198 lr 100078c8 code 1 in sh[10000000+14000] [ 4.386829] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX [ 4.391542] init[1]: code: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX [ 4.400863] init[74]: code: 90010024 bf61000c 91490a7c 3fa01002 3be00000 7d3e4b78 3bbd0c20 3b600000 [ 4.409867] init[74]: code: 3b9d0040 7c7fe02e 2f830000 419e0028 <89230000> 2f890000 41be001c 4b7f6e79 This patch fixes it by preparing complete lines in a buffer and printing it at once. Fixes: 88b0fe1757359 ("powerpc: Add show_user_instructions()") Cc: Murilo Opsfelder Araujo Signed-off-by: Christophe Leroy --- v3: no change v2: Using seq_buf and reworked the loop to avoid redundant prints. arch/powerpc/kernel/process.c | 37 +++++++++++++++++++------------------ 1 file changed, 19 insertions(+), 18 deletions(-) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index e108e1ef2b85..2a39f7aca846 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #include @@ -1303,33 +1304,33 @@ static void show_instructions(struct pt_regs *regs) void show_user_instructions(struct pt_regs *regs) { unsigned long pc; - int i; + int n = instructions_to_print; + struct seq_buf s; + char buf[96]; /* enough for 8 times 9 + 2 chars */ pc = regs->nip - (instructions_to_print * 3 / 4 * sizeof(int)); - pr_info("%s[%d]: code: ", current->comm, current->pid); + seq_buf_init(&s, buf, sizeof(buf)); - for (i = 0; i < instructions_to_print; i++) { - int instr; + while (n) { + int i; - if (!(i % 8) && (i > 0)) { - pr_cont("\n"); - pr_info("%s[%d]: code: ", current->comm, current->pid); - } + seq_buf_clear(&s); - if (probe_kernel_address((const void *)pc, instr)) { - pr_cont("XXXXXXXX "); - } else { - if (regs->nip == pc) - pr_cont("<%08x> ", instr); - else - pr_cont("%08x ", instr); + for (i = 0; i < 8 && n; i++, n--, pc += sizeof(int)) { + int instr; + + if (probe_kernel_address((const void *)pc, instr)) { + seq_buf_puts(&s, "XXXXXXXX "); + continue; + } + seq_buf_printf(&s, regs->nip == pc ? "<%08x> " : "%08x ", instr); } - pc += sizeof(int); + if (!seq_buf_has_overflowed(&s)) + pr_info("%s[%d]: code: %s\n", current->comm, + current->pid, s.buffer); } - - pr_cont("\n"); } struct regbit { -- 2.13.3