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=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 8E3AAC55178 for ; Thu, 29 Oct 2020 10:30:19 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 0330720825 for ; Thu, 29 Oct 2020 10:30:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="jmxSoSiY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0330720825 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-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=RkMoVCnGU5KZO62d7o4lakXb/slbBI2sZac4M7QU+TM=; b=jmxSoSiYGBGeyy00ilaMPcEHm 5/dhACr6vDlBq6LSRSkcTJpABB+GngHv/El8L12NPP6xvnJ3+IGHfIDGvVrksVtHCYv7eJ5ak6Id5 n0p6byz5MHrWf2IQEavyS72MePtyNKELN9ZivBt0F+Nu4RNbz4z7xOP0T+UJ+jnPL8WCMXz6Xi4Tn nOeWs0W/fAOWMuC2qVegj4O0ckmzv2SYNq/Tk1L8R4C2VsWXZv1wkMUWmZU/ViBZZvwBW3nqRRIBl rqISFuPgTqA/+dsA7o4tsg0YXnMnFOEHYF9MrJkGd3r7e7/WeY1aguLxHlck3GKKZF0whv8rv1LyI 0cTekAcfw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kY5Ay-0001ar-Q1; Thu, 29 Oct 2020 10:29:00 +0000 Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kY5Ax-0001aH-73; Thu, 29 Oct 2020 10:28:59 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 2D758301179; Thu, 29 Oct 2020 11:28:55 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1887D20409A75; Thu, 29 Oct 2020 11:28:55 +0100 (CET) Date: Thu, 29 Oct 2020 11:28:55 +0100 From: Peter Zijlstra To: Ard Biesheuvel Subject: Re: [PATCH v2] arm64: implement support for static call trampolines Message-ID: <20201029102855.GJ2628@hirez.programming.kicks-ass.net> References: <20201028184114.6834-1-ardb@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201028184114.6834-1-ardb@kernel.org> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Oct 28, 2020 at 07:41:14PM +0100, Ard Biesheuvel wrote: > This turned nasty really quickly when I realized that any sleeping task > could have been interrupted right in the middle of the ADRP/ADD pair > that we emit for static call targets that are out of immediate branching > range. Ha! Yes, that's a 'problem' allright. On x86 we normally only patch a single instruction because of this, however we have some kprobe code that has this issue and there we use tasks_rcu when PREEMPT=y. Now, let me try and read this patch properly.. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel