From patchwork Wed Nov 22 09:42:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13464372 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61CEF16407; Wed, 22 Nov 2023 09:44:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rTp3IgyI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50C67C433C7; Wed, 22 Nov 2023 09:44:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1700646270; bh=qEFrCNf3UEgHGW1T9wtS9jRJz/KS9KwPB3lxI2GEsTI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=rTp3IgyIvQfGD4I+L4TFOAbCJv9NbsiNeIDD4RtpVFyB4VfP3fsoai+tC4z4rivNB 8csRCTYL8ZxeIFyOEnSQA4auqXLMjPB0TV4q9PD4M8mgIYeKJidyttb6RB1TqgN3n/ 7KFCMpd6Y97LNcgEUgDa3TuB2NG38oyO3WYbYyT4ZlzJStWJg4OpYtI1zx1GNbFLcQ EqvGVx0LQC1NgAEZKJhwgqD7BpUehJeQAuBogQ81mPWkWennLwbFNmzi6M9MU9ePt7 EfPhNaYflYB6bWpv0JVKbnZGesMDPr2M3n8dHIwjEE+6mu+EB7/vi4iVvbD9/uCSfp qfBU5xs5TJplw== From: Mark Brown Date: Wed, 22 Nov 2023 09:42:23 +0000 Subject: [PATCH v7 13/39] arm64/mm: Map pages for guarded control stack Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231122-arm64-gcs-v7-13-201c483bd775@kernel.org> References: <20231122-arm64-gcs-v7-0-201c483bd775@kernel.org> In-Reply-To: <20231122-arm64-gcs-v7-0-201c483bd775@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 , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , 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-0438c X-Developer-Signature: v=1; a=openpgp-sha256; l=1837; i=broonie@kernel.org; h=from:subject:message-id; bh=qEFrCNf3UEgHGW1T9wtS9jRJz/KS9KwPB3lxI2GEsTI=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBlXc0A24D56zutL8bLQvd52fo0wC43SRULlWAh1 +rU/4PE4q6JATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZV3NAAAKCRAk1otyXVSH 0HxeB/wMjuD6MVRsjymmm5q0PFo3mPpIDfrsn5bfPM93xyIkhexzp3o8MKMLZJR6AyWc5SU9ANA 9VNb9/Gq2SqulwM+T75NERQoIaX5QN0rnERoUsbZEovn2OVcl1rKgSR9V3pSg6Qe7bTHQI1RXba 52pV6lnw7K6QWG67Rs68SOCjwuPipie41cnu7hHYrKAVPUJgJ3xAaTF3zvDCHGppy2hPtemSDue xvPJt2OEUG/I7wwXpBQXAIdu64425sWrMATEdrAKaBbTDiRIX3QHYitwt4URVvOPC092qkbtgUq ocdLzNoIZ+MRZVauVM6J+z8pX5L1QoZViXQ6EXKLKo+5igsQ X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB 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 | 9 +++++++++ arch/arm64/mm/mmap.c | 13 ++++++++++++- 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h index c21849ffdd88..6d3fe6433a62 100644 --- a/arch/arm64/include/asm/mman.h +++ b/arch/arm64/include/asm/mman.h @@ -61,6 +61,15 @@ 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, and the mm + * core can't cope with a shared GCS. + */ + if (vm_flags & (VM_EXEC | VM_ARM64_BTI | VM_SHARED)) + return false; + } + return true; } diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index 645fe60d000f..605d4e6edc1d 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;