From patchwork Wed Oct 27 02:32:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?546L6LSH?= X-Patchwork-Id: 12586219 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 921DFC433FE for ; Wed, 27 Oct 2021 02:32:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D2EE610EA for ; Wed, 27 Oct 2021 02:32:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238179AbhJ0CfN (ORCPT ); Tue, 26 Oct 2021 22:35:13 -0400 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:56719 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232221AbhJ0CfM (ORCPT ); Tue, 26 Oct 2021 22:35:12 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R881e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=yun.wang@linux.alibaba.com;NM=1;PH=DS;RN=30;SR=0;TI=SMTPD_---0UtpxLVt_1635301961; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UtpxLVt_1635301961) by smtp.aliyun-inc.com(127.0.0.1); Wed, 27 Oct 2021 10:32:43 +0800 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 , 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 From: =?utf-8?b?546L6LSH?= Subject: [PATCH v6 0/2] fix & prevent the missing preemption disabling Message-ID: Date: Wed, 27 Oct 2021 10:32:41 +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 Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-parisc@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. And since the internal using of trace_test_and_set_recursion() and trace_clear_recursion() also require preemption to be disabled, we can just merge the logical together. Patch 1/2 will make sure preemption disabled when recursion lock succeed, patch 2/2 will do smp_processor_id() checking after trylock() to address the issue. v1: https://lore.kernel.org/all/8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com/ v2: https://lore.kernel.org/all/b1d7fe43-ce84-0ed7-32f7-ea1d12d0b716@linux.alibaba.com/ v3: https://lore.kernel.org/all/609b565a-ed6e-a1da-f025-166691b5d994@linux.alibaba.com/ V4: https://lore.kernel.org/all/32a36348-69ee-6464-390c-3a8d6e9d2b53@linux.alibaba.com/ V5: https://lore.kernel.org/all/3ca92dc9-ea04-ddc2-71cd-524bfa5a5721@linux.alibaba.com/ Michael Wang (2): ftrace: disable preemption when recursion locked 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 | 13 ++++++++++++- kernel/livepatch/patch.c | 13 +++++++------ kernel/trace/ftrace.c | 15 +++++---------- kernel/trace/trace_event_perf.c | 6 +++--- kernel/trace/trace_functions.c | 5 ----- 10 files changed, 27 insertions(+), 35 deletions(-)