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=-10.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 60F6EC64E7C for ; Wed, 2 Dec 2020 17:44:06 +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 A59012086A for ; Wed, 2 Dec 2020 17:44:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A59012086A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.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=H7Fgj/IIi+bD4syKyC52W4pzWTlIjl+QB3vvuf1J6rY=; b=0zfZp2JDgkWW5Y1/SjN51knAD f9ZBA8dlmsPCYt1h0Rp3SSiXkpwa6sbKo6A0ptVwCcgE5v8hE0i0UU9XwaRTy7nJL1SVxW8tH2n0S e88OMvMJC5YMEjxzgkjAXLj6n8W4rI23JcEXN9TfrFGIQ2fPap5qBsakRpeAOMh0aMnwgKvUB2Kwn Fx9SzFuEteIKi3YCw3u/Dup7ud9n4wpAI1FukJAMCywgZNZ32AYe86ET5Lny6h0LaAD52jDkbw1WX uQpDQ+ZUA1HI7llMp/qqUTernYlMHhCZ0x1o1DwDRAAmC88XxKbpGRfjzKDdQsSt57RDJPEau4KFe zm93hTplA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kkW9Z-0006a1-DJ; Wed, 02 Dec 2020 17:42:57 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kkW9X-0006Yw-Hz for linux-arm-kernel@lists.infradead.org; Wed, 02 Dec 2020 17:42:56 +0000 Date: Wed, 2 Dec 2020 17:42:48 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606930974; bh=cqmV/I9FRZ4kYw4yyZj/9mTxHnFQnGQs3KzuxScuNO8=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=qPNDX4Y6a/KFdERBe6ZlJGjU8wbI/C1LlTJNYV9/Jb779ie1B/mgOVK74wQyVQlEI CJmAjK1AjgcOmRuS7LUdRfDU3AZzhLLU4tmHif4kpoX6IXvCXly/f6HVZHkdEiVaxy ySa6YEOtZFQ+pHd1RMQhC0Hbfi3HwSvLI4DZNJUc= From: Will Deacon To: Qais Yousef Subject: Re: [PATCH v4 04/14] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Message-ID: <20201202174247.GB29939@willie-the-truck> References: <20201124155039.13804-1-will@kernel.org> <20201124155039.13804-5-will@kernel.org> <20201127131217.skekrybqjdidm5ki@e107158-lin.cambridge.arm.com> <20201201165633.GC27783@willie-the-truck> <20201202135216.7jilpcvocnqqp5aj@e107158-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201202135216.7jilpcvocnqqp5aj@e107158-lin.cambridge.arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201202_124255_713074_2D6199E5 X-CRM114-Status: GOOD ( 22.15 ) 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: linux-arch@vger.kernel.org, Marc Zyngier , kernel-team@android.com, Vincent Guittot , Juri Lelli , Quentin Perret , Peter Zijlstra , Catalin Marinas , Johannes Weiner , linux-kernel@vger.kernel.org, Ingo Molnar , Li Zefan , Greg Kroah-Hartman , Tejun Heo , Suren Baghdasaryan , Morten Rasmussen , 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, Dec 02, 2020 at 01:52:16PM +0000, Qais Yousef wrote: > On 12/01/20 16:56, Will Deacon wrote: > > On Fri, Nov 27, 2020 at 01:12:17PM +0000, Qais Yousef wrote: > > > On 11/24/20 15:50, Will Deacon wrote: > > > > Scheduling a 32-bit application on a 64-bit-only CPU is a bad idea. > > > > > > > > Ensure that 32-bit applications always take the slow-path when returning > > > > to userspace on a system with mismatched support at EL0, so that we can > > > > avoid trying to run on a 64-bit-only CPU and force a SIGKILL instead. > > > > > > > > Signed-off-by: Will Deacon > > > > --- > > > > > > nit: We drop this patch at the end. Can't we avoid it altogether instead? > > > > I did it like this so that the last patch can be reverted for > > testing/debugging, but also because I think it helps the structure of the > > series. > > Cool. I had a comment about the barrier(), you were worried about > cpu_affinity_invalid() being inlined by the compiler and then things get > mangled such that TIF_NOTIFY_RESUME clearing is moved after the call as you > described? Can the compiler move things if cpu_affinity_invalid() is a proper > function call (not inlined)? I think function calls implicitly clobber memory, but you'd have to annotate the thing as noinline to prevent it being inlined. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel