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[209.85.208.180]) by smtp.gmail.com with ESMTPSA id g68sm4180941ljg.53.2019.02.18.16.24.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Feb 2019 16:24:46 -0800 (PST) Received: by mail-lj1-f180.google.com with SMTP id f24-v6so15905017ljk.0 for ; Mon, 18 Feb 2019 16:24:46 -0800 (PST) X-Received: by 2002:a2e:9117:: with SMTP id m23mr13676200ljg.94.1550535886008; Mon, 18 Feb 2019 16:24:46 -0800 (PST) MIME-Version: 1.0 References: <20190213140025.GB6346@brain-police> <20190213142524.GW32494@hirez.programming.kicks-ass.net> <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> In-Reply-To: <9e037d68-75e7-1beb-0c9c-33a7ffeced1b@zytor.com> From: Linus Torvalds Date: Mon, 18 Feb 2019 16:24:30 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] sched/x86: Save [ER]FLAGS on context switch To: "H. Peter Anvin" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190218_162453_041093_3FCFDA6A X-CRM114-Status: GOOD ( 11.44 ) 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: Denys Vlasenko , Josh Poimboeuf , Julien Thierry , Peter Zijlstra , Catalin Marinas , valentin.schneider@arm.com, Will Deacon , Linux List Kernel Mailing , Andy Lutomirski , Ingo Molnar , James Morse , Andrew Lutomirski , Brian Gerst , Borislav Petkov , Thomas Gleixner , Ingo Molnar , "linux-alpha@vger.kernel.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 Mon, Feb 18, 2019 at 2:31 PM H. Peter Anvin wrote: > > The question is what "fix it" means. I'm really concerned about AC escapes, > and everyone else should be, too. I do think that it might be the right thing to do to add some kind of WARN_ON_ONCE() for AC being set in various can-reschedule situations. We'd just have to abstract it sanely. I'm sure arm64 has the exact same issue with PAN - maybe it saves properly, but the same "we wouldn't want to go through the scheduler with PAN clear". On x86, we might as well check DF at the same time as AC. Linus _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel