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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1is7wh-0006go-KU; Thu, 16 Jan 2020 16:24:35 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1is7wZ-0006f6-Q4 for linux-arm-kernel@lists.infradead.org; Thu, 16 Jan 2020 16:24:34 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9CB5C1396; Thu, 16 Jan 2020 08:24:18 -0800 (PST) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.197.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D709D3F68E; Thu, 16 Jan 2020 08:24:16 -0800 (PST) Date: Thu, 16 Jan 2020 16:24:14 +0000 From: Catalin Marinas To: Amit Daniel Kachhap Subject: Re: [PATCH v3 06/16] arm64: enable ptrauth earlier Message-ID: <20200116162414.GF10277@arrakis.emea.arm.com> References: <1576486038-9899-1-git-send-email-amit.kachhap@arm.com> <1576486038-9899-7-git-send-email-amit.kachhap@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1576486038-9899-7-git-send-email-amit.kachhap@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-20200116_082427_891673_E071418C X-CRM114-Status: GOOD ( 11.48 ) 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 , Kees Cook , Suzuki K Poulose , Ard Biesheuvel , Richard Henderson , Kristina Martsenko , James Morse , Ramana Radhakrishnan , Mark Brown , Vincenzo Frascino , Will Deacon , Dave Martin , 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 Mon, Dec 16, 2019 at 02:17:08PM +0530, Amit Daniel Kachhap wrote: > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index 5aaf1bb..c59c28f 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -13,6 +13,7 @@ > #include > #include > > +#include > #include > #include > #include > @@ -713,6 +714,7 @@ secondary_startup: > * Common entry point for secondary CPUs. > */ > bl __cpu_secondary_check52bitva > + bl __cpu_secondary_checkptrauth > mov x0, #ARM64_CPU_BOOT_LATE > bl __cpu_setup // initialise processor > adrp x1, swapper_pg_dir > @@ -831,6 +833,24 @@ __no_granule_support: > early_park_cpu CPU_STUCK_REASON_NO_GRAN > ENDPROC(__no_granule_support) > > +ENTRY(__cpu_secondary_checkptrauth) > +#ifdef CONFIG_ARM64_PTR_AUTH > + /* Check if the CPU supports ptrauth */ > + mrs x2, id_aa64isar1_el1 > + ubfx x2, x2, #ID_AA64ISAR1_APA_SHIFT, #8 > + cbnz x2, 1f > +alternative_if ARM64_HAS_ADDRESS_AUTH > + mov x3, 1 > +alternative_else > + mov x3, 0 > +alternative_endif > + cbz x3, 1f > + /* Park the mismatched secondary CPU */ > + early_park_cpu CPU_STUCK_REASON_NO_PTRAUTH > +#endif > +1: ret > +ENDPROC(__cpu_secondary_checkptrauth) Do we actually need to park secondary CPUs early? Let's say a secondary CPU doesn't have PAC, __cpu_setup won't set the corresponding SCTLR_EL1 bits and the instructions are NOPs. Wouldn't the cpufeature framework park it later anyway? -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel