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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8189C433FE for ; Wed, 13 Oct 2021 03:17:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8EE360C40 for ; Wed, 13 Oct 2021 03:17:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230030AbhJMDTH (ORCPT ); Tue, 12 Oct 2021 23:19:07 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:46025 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229526AbhJMDTG (ORCPT ); Tue, 12 Oct 2021 23:19:06 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R471e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=yun.wang@linux.alibaba.com;NM=1;PH=DS;RN=31;SR=0;TI=SMTPD_---0UrdejSK_1634095017; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UrdejSK_1634095017) by smtp.aliyun-inc.com(127.0.0.1); Wed, 13 Oct 2021 11:16:58 +0800 Subject: [PATCH v2 0/2] fix & prevent the missing preemption disabling From: =?UTF-8?B?546L6LSH?= To: Guo Ren , Steven Rostedt , Ingo Molnar , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Colin Ian King , Masami Hiramatsu , "Peter Zijlstra (Intel)" , Nicholas Piggin , Jisheng Zhang , linux-csky@vger.kernel.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, live-patching@vger.kernel.org References: <8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com> Message-ID: <1a8e8d73-b508-f90b-0d82-eb2da45a720e@linux.alibaba.com> Date: Wed, 13 Oct 2021 11:16:56 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org The testing show that perf_ftrace_function_call() are using smp_processor_id() with preemption enabled, all the checking on CPU could be wrong after preemption. As Peter point out, the section between ftrace_test_recursion_trylock/unlock() pair require the preemption to be disabled as 'Documentation/trace/ftrace-uses.rst' explained, but currently the work is done outside of the helpers. Patch 1/2 will make sure preemption disabled after trylock() succeed, patch 2/2 will do smp_processor_id() checking after trylock to address the issue. Michael Wang (2): ftrace: disable preemption between ftrace_test_recursion_trylock/unlock() ftrace: do CPU checking after preemption disabled arch/csky/kernel/probes/ftrace.c | 2 -- arch/parisc/kernel/ftrace.c | 2 -- arch/powerpc/kernel/kprobes-ftrace.c | 2 -- arch/riscv/kernel/probes/ftrace.c | 2 -- arch/x86/kernel/kprobes/ftrace.c | 2 -- include/linux/trace_recursion.h | 22 +++++++++++++++++++++- kernel/livepatch/patch.c | 6 ------ kernel/trace/trace_event_perf.c | 6 +++--- kernel/trace/trace_functions.c | 5 ----- 9 files changed, 24 insertions(+), 25 deletions(-) -- 1.8.3.1