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Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:52926) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1l4M4P-0004Ig-0X; Tue, 26 Jan 2021 10:59:37 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1l4M4K-0003jk-UC; Tue, 26 Jan 2021 10:59:32 +0000 Date: Tue, 26 Jan 2021 10:59:32 +0000 From: Russell King - ARM Linux admin To: Lecopzer Chen Subject: Re: [PATCH] ARM: mm: harden branch predictor before opening interrupts during fault Message-ID: <20210126105932.GG1551@shell.armlinux.org.uk> References: <20201203092738.11866-1-lecopzer.chen@mediatek.com> <20210126091708.3461-1-lecopzer.chen@mediatek.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210126091708.3461-1-lecopzer.chen@mediatek.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-20210126_055941_280743_BD921C78 X-CRM114-Status: GOOD ( 13.01 ) 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: marc.zyngier@arm.com, bigeasy@linutronix.de, linux-kernel@vger.kernel.org, peterx@redhat.com, rppt@kernel.org, akpm@linux-foundation.org, walken@google.com, yj.chiang@mediatek.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 Tue, Jan 26, 2021 at 05:17:08PM +0800, Lecopzer Chen wrote: > Hi all, > > I don't see any fix for this issue now(maybe I missed it..?), > could we fix this if there is better solution? > This issue exists almost two years. I don't think anyone provided an acceptable patch. The first patch moved the hardening out of the translation/section fault handling. Since the kernel is mapped with sections, these are above TASK_SIZE, and the whole point of the branch prediction hardening is to prevent the prediction in the kernel being exploited, missing the hardening effectively makes the mitigation useless. The discussion in February 2019 never concluded from what I can see. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel