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 B56FCC433F5 for ; Tue, 12 Oct 2021 05:40:56 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 43C6C61076 for ; Tue, 12 Oct 2021 05:40:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 43C6C61076 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:References:To:From:Subject:Reply-To:Cc:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=cFQwuIljHN6Kuhr4bXXpXZOENILtJiKJwsHpwXisMDI=; b=T4PCATf2W7bm+9m8eWMSy1Cr45 Jwl3QAA28chmsMIuX6kDvfGejhNqQ4NCHIQ5EVUIUNAtxkg2fmR2dzhmrR0uhxpo7aoi8XOktAnxl cQHlGkMGobF6BS+HHEOsH1CU9oC7p2HcEjWi078lUIjgbhVU4w3b7f3p+fau3x2agcgQjLKam8E8A lHq02wUHdlwvr47Skmgk9BJ5pTsZm+eDWiYvjPRkh89Lk0pKvd5T8LPvhfAZQQ+zAKeaQ1unireQo idYWMidlxNyUgP+vF0qyTs8gYU1k60LROeymBMCYVB41D1cr2tqfSJCKbRz2a3KeAb2W4O3wlb9yw Bmg8p0WA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1maAWm-00BdkK-CK; Tue, 12 Oct 2021 05:40:40 +0000 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1maAWi-00Bdif-V9 for linux-riscv@lists.infradead.org; Tue, 12 Oct 2021 05:40:38 +0000 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R211e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04357; MF=yun.wang@linux.alibaba.com; NM=1; PH=DS; RN=31; SR=0; TI=SMTPD_---0UrY3qZU_1634017231; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UrY3qZU_1634017231) by smtp.aliyun-inc.com(127.0.0.1); Tue, 12 Oct 2021 13:40:32 +0800 Subject: [PATCH 2/2] ftrace: prevent preemption in perf_ftrace_function_call() 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: <7ec34e08-a357-58d6-2ce4-c7472d8b0381@linux.alibaba.com> Date: Tue, 12 Oct 2021 13:40:31 +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-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211011_224037_199937_BD07173E X-CRM114-Status: GOOD ( 11.95 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org With CONFIG_DEBUG_PREEMPT we observed reports like: BUG: using smp_processor_id() in preemptible caller is perf_ftrace_function_call+0x6f/0x2e0 CPU: 1 PID: 680 Comm: a.out Not tainted Call Trace: dump_stack_lvl+0x8d/0xcf check_preemption_disabled+0x104/0x110 ? optimize_nops.isra.7+0x230/0x230 ? text_poke_bp_batch+0x9f/0x310 perf_ftrace_function_call+0x6f/0x2e0 ... __text_poke+0x5/0x620 text_poke_bp_batch+0x9f/0x310 This telling us the CPU could be changed after task is preempted, and the checking on CPU before preemption will be invalid. This patch just turn off preemption in perf_ftrace_function_call() to prevent CPU changing. CC: Steven Rostedt Reported-by: Abaci Signed-off-by: Michael Wang --- kernel/trace/trace_event_perf.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index 6aed10e..33c2f76 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -441,12 +441,19 @@ void perf_trace_buf_update(void *record, u16 type) if (!rcu_is_watching()) return; + /* + * Prevent CPU changing from now on. rcu must + * be in watching if the task was migrated and + * scheduled. + */ + preempt_disable_notrace(); + if ((unsigned long)ops->private != smp_processor_id()) - return; + goto out; bit = ftrace_test_recursion_trylock(ip, parent_ip); if (bit < 0) - return; + goto out; event = container_of(ops, struct perf_event, ftrace_ops); @@ -468,16 +475,18 @@ void perf_trace_buf_update(void *record, u16 type) entry = perf_trace_buf_alloc(ENTRY_SIZE, NULL, &rctx); if (!entry) - goto out; + goto unlock; entry->ip = ip; entry->parent_ip = parent_ip; perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN, 1, ®s, &head, NULL); -out: +unlock: ftrace_test_recursion_unlock(bit); #undef ENTRY_SIZE +out: + preempt_enable_notrace(); } static int perf_ftrace_function_register(struct perf_event *event) -- 1.8.3.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv