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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, 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 21653C43381 for ; Tue, 19 Feb 2019 09:44:57 +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 D930D2146E for ; Tue, 19 Feb 2019 09:44:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="hsC+8Lmz"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ky8ytGJO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D930D2146E 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+infradead-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=bombadil.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=zLD59Q8UMdiuMGyGexTPExKf6wlFhYJoQpatITAFJ0k=; b=hsC+8LmzuhCuSk IOdcyWe6zi7gRZBjgkbjc1nUhqqha3IWHAv7rW1GQmq5khiyPPXUnIrlCnUOtQlFALH2gf4WAtvPB bdCntCxl8PMLKYxSrBPPUVog9wLzdq6koUscAGQyyEOPw44hn/hRO6eCmDAm2+XCwJ87i7hx7ZLIw BXe/pv6ro9dSV5QN9VryppNrhm9fQskBAt7/1nT6e84nQM8L1Ov8SqTKWvuNppcB5IVHztyluJny0 SlnNMPbRExIgIMj1uRd2u3zbNTRWr/dog61MXeU+gAPvwEjfLPqSa9J6jixn3ukNr/OvMSo11bfxT 42ng4ouXi0ranmVo7hzg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gw1xI-0003uo-IW; Tue, 19 Feb 2019 09:44:48 +0000 Received: from merlin.infradead.org ([2001:8b0:10b:1231::1]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gw1xG-0003uW-Np for linux-arm-kernel@bombadil.infradead.org; Tue, 19 Feb 2019 09:44:46 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding: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=BSKboyCAOkwlTQlKVtpuNo+zZmTvDQywmdcs6fHkXqM=; b=ky8ytGJOQ04HHG8DhPq+zcPu4 sa6f0/O8OTIaEJ0B5ryEF+9jsjEetVerBJeHnW+nL+jC1g5ZGd6lA+xmXVwPFQPrmM/dtGtJi17iY RqyTToWoJNxrssViqpibcJLFJbohBjqeCOxOpzKooJlr6Wfp1RjrOk4dLxV3zw+ew3FsHpit1dv5h WYxd/P1VpAuVIvSNzp2Bw2XM7i57Y1CYbTumuQ4Ad2oj1+Pwndw2lq6jllr9IoQH44GW3eXETsgLb pjguJ02CbPrSN9yEeq6/AaRWShX9fG/WG+lPzuo8Ye0/PMDstZBT3lUs8zNEiDKbMY9tR1+rOL+qm orgUlOptA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gw1xB-0008TD-VJ; Tue, 19 Feb 2019 09:44:42 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 03AD4285202CC; Tue, 19 Feb 2019 10:44:39 +0100 (CET) Date: Tue, 19 Feb 2019 10:44:38 +0100 From: Peter Zijlstra To: "H. Peter Anvin" Subject: Re: [PATCH] sched/x86: Save [ER]FLAGS on context switch Message-ID: <20190219094438.GV32534@hirez.programming.kicks-ass.net> References: <20190213144145.GY32494@hirez.programming.kicks-ass.net> <20190213154532.GQ32534@hirez.programming.kicks-ass.net> <20190213222146.GC32494@hirez.programming.kicks-ass.net> <20190214101429.GD32494@hirez.programming.kicks-ass.net> <20ABBED1-E505-45F6-8520-FB93786DF9A9@zytor.com> <20190216103044.GR32494@hirez.programming.kicks-ass.net> <9e037d68-75e7-1beb-0c9c-33a7ffeced1b@zytor.com> <20190219090409.GW32494@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190219090409.GW32494@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dvlasenk@redhat.com, jpoimboe@redhat.com, Julien Thierry , catalin.marinas@arm.com, valentin.schneider@arm.com, Will Deacon , linux-kernel@vger.kernel.org, Andy Lutomirski , mingo@redhat.com, james.morse@arm.com, luto@kernel.org, brgerst@gmail.com, bp@alien8.de, tglx@linutronix.de, torvalds@linux-foundation.org, Ingo Molnar , 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+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Feb 19, 2019 at 10:04:09AM +0100, Peter Zijlstra wrote: > > Does that make more sense? > > It appears to me you're going about it backwards. So how about you do a GCC plugin that verifies limits on code-gen between user_access_begin/user_access_end() ? - No CALL/RET - implies user_access_end() happens - implies no fentry hooks - No __preempt_count frobbing - No tracepoints - ... That way you put the burden on the special code, not on the rest of the kernel. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel