From patchwork Tue Aug 22 13:56:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13360834 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27B79EE49AF for ; Tue, 22 Aug 2023 14:04:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236382AbjHVOEt (ORCPT ); Tue, 22 Aug 2023 10:04:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236358AbjHVOEs (ORCPT ); Tue, 22 Aug 2023 10:04:48 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12ED9E45; Tue, 22 Aug 2023 07:04:21 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4A4DA65792; Tue, 22 Aug 2023 14:04:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD285C433C8; Tue, 22 Aug 2023 14:04:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1692713057; bh=fYSc6YldDz9f4Wg0F4vCCpyazEEr65gHlcDJxqefLXM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=dRAAsGX9NQcMTa6eDbu6Tqs9RxRB5S5O4R9jCuHb2OQzuZkg4eItQ1lYOm3LAkrrB 7oYfctWxhLj/jt70PAvNfFtMY9G9e5i+ecr7xA61ELZwQo6kHP/NWVFIAiIu3f+3+4 H90+VbQOlXvBNgtiFTibSSe2vAvRZ/sQby+T6aJt/RBGpCqiiKW4cLZlkwdWAQDtbq Gp+Tdz+PPhLjTSw2Af0B1azcJik4Q51rrKko9u9U++73PXF/LZMSBnctKSHhse3OFE kKAL8bKKirnLI2q5/Y0dwJ6qjf0+DP4mkM8ysdhjYYQlorvtaS6vniIxJ/giKUdQA9 Nl+zR7rAwwaWg== From: Mark Brown Date: Tue, 22 Aug 2023 14:56:45 +0100 Subject: [PATCH v5 12/37] arm64/mm: Map pages for guarded control stack MIME-Version: 1.0 Message-Id: <20230822-arm64-gcs-v5-12-9ef181dd6324@kernel.org> References: <20230822-arm64-gcs-v5-0-9ef181dd6324@kernel.org> In-Reply-To: <20230822-arm64-gcs-v5-0-9ef181dd6324@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 , Kees Cook , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy Cc: "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , 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 0.13-dev-034f2 X-Developer-Signature: v=1; a=openpgp-sha256; l=1756; i=broonie@kernel.org; h=from:subject:message-id; bh=fYSc6YldDz9f4Wg0F4vCCpyazEEr65gHlcDJxqefLXM=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBk5L/5PuMIq9BeN3C01qO5ocLYTnlKxWd1K2qibZTk qwPJmcmJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZOS/+QAKCRAk1otyXVSH0IUQB/ 9L+p/pe8VJG6Xh+181btNdS+8+jqn1Yk5PtFIxvU5J2m5z8vS9N1POMNvUX0r6O/SW5UoitDMDdz0L 8CJpwAh9YougsmhMN8+JzS5SAPv/Vh51y37mtNY5GfahOxketQtY1D2P955vTu0cDrsG/4l753eld4 3M591bLEc2Ke1tUf7tpsjZQR7VebXEdd5Lm+zcDr3e3JJGV5xLbv/uKjAVvUxxc5+Nx5aGTL+XpL4z qsnKGvb334j8M7hf84I4o1U0+ir3YzDo7udMaAZjAybVwDbLhJaD2XOHfiVzmTyps9zwcoJ7lVgFyw qCXDWPEi9HXbD8VkR+zsq41rp1BVF0 X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Map pages flagged as being part of a GCS as such rather than using the full set of generic VM flags. This is done using a conditional rather than extending the size of protection_map since that would make for a very sparse array. Signed-off-by: Mark Brown --- arch/arm64/include/asm/mman.h | 6 ++++++ arch/arm64/mm/mmap.c | 13 ++++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h index c21849ffdd88..4c4615867713 100644 --- a/arch/arm64/include/asm/mman.h +++ b/arch/arm64/include/asm/mman.h @@ -61,6 +61,12 @@ static inline bool arch_validate_flags(unsigned long vm_flags) return false; } + if (system_supports_gcs() && (vm_flags & VM_SHADOW_STACK)) { + /* An executable GCS isn't a good idea */ + if (vm_flags & (VM_EXEC | VM_ARM64_BTI)) + return false; + } + return true; } diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index 8f5b7ce857ed..e6fc7ef83ea1 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -79,9 +79,20 @@ arch_initcall(adjust_protection_map); pgprot_t vm_get_page_prot(unsigned long vm_flags) { - pteval_t prot = pgprot_val(protection_map[vm_flags & + pteval_t prot; + + /* If this is a GCS then only interpret VM_WRITE. */ + if (system_supports_gcs() && (vm_flags & VM_SHADOW_STACK)) { + if (vm_flags & VM_WRITE) + prot = _PAGE_GCS; + else + prot = _PAGE_GCS_RO; + } else { + prot = pgprot_val(protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]); + } + /* VM_ARM64_BTI on a GCS is rejected in arch_valdiate_flags() */ if (vm_flags & VM_ARM64_BTI) prot |= PTE_GP;