From patchwork Wed Aug 28 23:27:21 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13782207 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id A27D8C71150 for ; Wed, 28 Aug 2024 23:34:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=KtmuWL5rPnJxunKis4r+zJuOmfs6tLevqw0vcnqTYxQ=; b=OIQ5+IipsJ5vA6/rd8qsOfqlET XEHkKb4LHQMVRsLennVipRR0yNH6E+Kz9IRqAnKewpZrCozo5pycvqBjag5ZxST2x6WIyAuTfNQcc gOuWxLhcvS3NFvgqO3WbPby7t0AOGkFW7O09SZclQvNLzGjTKb7OJdnJXHy0iK5im+IRbIB8tvhyP 7p+5zCL8p1PTVnGSRz7/tLKPC5jU/U4hCir9awBNzZPsFBB8UkagDVjzhF9dNVGBWWUT7LGjs7YP9 YWShnkBOrNMjTfLf3MX7VbPoI3SKQjVMP6CBybkjo+dmqw7PPdPAfznDIpkcuogHLJXfQ9d6ENwxl o18hF7pw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sjSBC-0000000HOPt-1u6Y; Wed, 28 Aug 2024 23:34:22 +0000 Received: from sin.source.kernel.org ([145.40.73.55]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sjS6A-0000000HLtE-3maY; Wed, 28 Aug 2024 23:29:12 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 09C74CE1736; Wed, 28 Aug 2024 23:29:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76D85C4CEC9; Wed, 28 Aug 2024 23:29:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724887748; bh=rOh4m4fj2wClbocRq0H+LpbzuLewpkO3M5BRFF5QA9g=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ZtDMwdQpJIDs2Rkwg0UYeDSZGl9Kgy35c06eDIK4/xNomEaD++8/p8t2QXdJEAztH wSDe8Jup97ATXtYoBygYSHUOvxgA0EtDFbcoVHiHXkZU64s+4e7QdTpYwjHwYUNNA4 fmXhbKdf9yiRBra8gOySoZ5GyegNK29pluB9SC4oXQpTUsASjznj/+gelnrStbMUCQ mzoDrv+bTHH8lLa0Z0jhD+yocQgZqM15phOtwWzVvG0Hlip8JN4BaxASDLVEXK4jb0 ciKTdIgx29iXFhoHHZ6RBmDIqv5QKOIIhKW1Dsd8YOdLxp4HP/wwySaJA5xzlpY4PO wYLCOROxVvtxw== From: Mark Brown Date: Thu, 29 Aug 2024 00:27:21 +0100 Subject: [PATCH v12 05/39] arm64: Document boot requirements for Guarded Control Stacks MIME-Version: 1.0 Message-Id: <20240829-arm64-gcs-v12-5-42fec947436a@kernel.org> References: <20240829-arm64-gcs-v12-0-42fec947436a@kernel.org> In-Reply-To: <20240829-arm64-gcs-v12-0-42fec947436a@kernel.org> To: Catalin Marinas , Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy , Kees Cook Cc: "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , Ross Burton , Yury Khrustalev , Wilco Dijkstra , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Mark Brown X-Mailer: b4 0.15-dev-37811 X-Developer-Signature: v=1; a=openpgp-sha256; l=2380; i=broonie@kernel.org; h=from:subject:message-id; bh=rOh4m4fj2wClbocRq0H+LpbzuLewpkO3M5BRFF5QA9g=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBmz7J8Z5KYwVa17Tubvy4OA5GT6N3rKn+DrkFI1TFj ZrKgfK2JATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZs+yfAAKCRAk1otyXVSH0MAcB/ 9SchQoHpvxwB9OxCqShz/dLftqcvRCIWxO9ZgoadV/U4Z50nuJqBdPypaRBS3bZjxOdOISP6XQ/CbU 3V5v+g4JXxiGcKDkpOi/GfmZ6t1GA/fgPZdFp7Ckdq8Pt0Zt/kwqhC/xwj48+HPd3g5yzqtjHeJ9VG yMVnneUwHH2TzyyvgGOyEVPO6GLr8arjGFoQ31TxvfiC+NskBEnNqcixA8MMAzSn+sZ8Xfxuyxmvgi MILIA4dpUWrY3uWd/x5J6+znHC9MOgmcxRhX2X16jFT1Zd5K/rFTcP6Wz1FXTwZMdn/T7eo3Yjz4iO RIWXdgHpzMXKw6EeHaoiWr7gUCLOry X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240828_162911_336640_0E54CBAF X-CRM114-Status: GOOD ( 11.56 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org FEAT_GCS introduces a number of new system registers, we require that access to these registers is not trapped when we identify that the feature is present. There is also a HCRX_EL2 control to make GCS operations functional. Since if GCS is enabled any function call instruction will cause a fault we also require that the feature be specifically disabled, existing kernels implicitly have this requirement and especially given that the MMU must be disabled it is difficult to see a situation where leaving GCS enabled would be reasonable. Reviewed-by: Thiago Jung Bauermann Reviewed-by: Catalin Marinas Signed-off-by: Mark Brown --- Documentation/arch/arm64/booting.rst | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/Documentation/arch/arm64/booting.rst b/Documentation/arch/arm64/booting.rst index b57776a68f15..aed6e9f47cf3 100644 --- a/Documentation/arch/arm64/booting.rst +++ b/Documentation/arch/arm64/booting.rst @@ -411,6 +411,38 @@ Before jumping into the kernel, the following conditions must be met: - HFGRWR_EL2.nPIRE0_EL1 (bit 57) must be initialised to 0b1. + - For CPUs with Guarded Control Stacks (FEAT_GCS): + + - GCSCR_EL1 must be initialised to 0. + + - GCSCRE0_EL1 must be initialised to 0. + + - If EL3 is present: + + - SCR_EL3.GCSEn (bit 39) must be initialised to 0b1. + + - If EL2 is present: + + - GCSCR_EL2 must be initialised to 0. + + - If the kernel is entered at EL1 and EL2 is present: + + - HCRX_EL2.GCSEn must be initialised to 0b1. + + - HFGITR_EL2.nGCSEPP (bit 59) must be initialised to 0b1. + + - HFGITR_EL2.nGCSSTR_EL1 (bit 58) must be initialised to 0b1. + + - HFGITR_EL2.nGCSPUSHM_EL1 (bit 57) must be initialised to 0b1. + + - HFGRTR_EL2.nGCS_EL1 (bit 53) must be initialised to 0b1. + + - HFGRTR_EL2.nGCS_EL0 (bit 52) must be initialised to 0b1. + + - HFGWTR_EL2.nGCS_EL1 (bit 53) must be initialised to 0b1. + + - HFGWTR_EL2.nGCS_EL0 (bit 52) must be initialised to 0b1. + The requirements described above for CPU mode, caches, MMUs, architected timers, coherency and system registers apply to all CPUs. All CPUs must enter the kernel in the same exception level. Where the values documented