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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 06B8AECDE43 for ; Sun, 21 Oct 2018 20:42:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ADF9520658 for ; Sun, 21 Oct 2018 20:42:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="IZdkW6tZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ADF9520658 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org 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 S1727559AbeJVE6K (ORCPT ); Mon, 22 Oct 2018 00:58:10 -0400 Received: from merlin.infradead.org ([205.233.59.134]:59214 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726188AbeJVE6K (ORCPT ); Mon, 22 Oct 2018 00:58:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=QL+jA+jVMjmOCldDrFZZQUY5L34QyAt5NNuevKFQrd8=; b=IZdkW6tZbbP3Bq5XP4JvhAkio/ a2322HPfV2fFSJX2j+31pytak3Ti0YnkUTEBUQxQwNd9j0aMSKOB4R3SNoA2ipEnYAZr1BP87xlpw IaPS4L+QEkh/riqB56S0C9W6vfanGoo4UAPSeybE659/BOJaWW8E81DKDTkWeMcAkzrbdGMf7omq3 Zt+tZOkG1OGIdStJnRXEKswk507lA5VPuC625/LrcfqmeIzXjhVJrow+0BnEEfWyyV3AzQMwpe/PD 4j0YHPsJafEUrQoJgYqvON1wLAwmvtS8O4/h0WsyTdXzoeBb8sQRGgEt00Z5O0i3cmhZk3osMH94p gLuo8jPw==; Received: from [167.98.65.38] (helo=worktop) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gEKYJ-0001oc-EL; Sun, 21 Oct 2018 20:42:23 +0000 Received: by worktop (Postfix, from userid 1000) id B72F46E0B3A; Sun, 21 Oct 2018 22:42:29 +0200 (CEST) Date: Sun, 21 Oct 2018 22:42:29 +0200 From: Peter Zijlstra To: Masami Hiramatsu Cc: Ingo Molnar , Andy Lutomirski , Alexei Starovoitov , Oleg Nesterov , "H . Peter Anvin" , Thomas Gleixner , X86 ML , Borislav Petkov , dwmw@amazon.co.uk, linux-kernel@vger.kernel.org Subject: Re: [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback() Message-ID: <20181021204229.GI4931@worktop.programming.kicks-ass.net> References: <154002887331.7627.10194920925792947001.stgit@devbox> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <154002887331.7627.10194920925792947001.stgit@devbox> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 20, 2018 at 06:47:53PM +0900, Masami Hiramatsu wrote: > Since commit a19b2e3d7839 ("kprobes/x86: Remove IRQ disabling from > ftrace-based/optimized kprobes”) removes local_irq_save/restore() > from optimized_callback(), the handler does not protected against > reschedule interrupt. If it is able to be preempted (rescheduled) > by such interrupt, we don't need to use _no_resched macro. must not. > Let's use preempt_enable() instead. > > Fixes: a19b2e3d7839 ("kprobes/x86: Remove IRQ disabling from ftrace-based/optimized kprobes”) > Link: https://lkml.kernel.org/r/37CB98C2-AF9B-475B-8B2D-7B414DC491F3@vmware.com > Reported-by: Nadav Amit > Signed-off-by: Masami Hiramatsu > --- > arch/x86/kernel/kprobes/opt.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c > index eaf02f2e7300..40b16b270656 100644 > --- a/arch/x86/kernel/kprobes/opt.c > +++ b/arch/x86/kernel/kprobes/opt.c > @@ -179,7 +179,7 @@ optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs) > opt_pre_handler(&op->kp, regs); > __this_cpu_write(current_kprobe, NULL); > } > - preempt_enable_no_resched(); > + preempt_enable(); > } Indeed, Acked-by: Peter Zijlstra (Intel)