Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753927AbdDCPUi (ORCPT ); Mon, 3 Apr 2017 11:20:38 -0400 Received: from foss.arm.com ([217.140.101.70]:60462 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751716AbdDCPUg (ORCPT ); Mon, 3 Apr 2017 11:20:36 -0400 From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, arnd@arndb.de, catalin.marinas@arm.com, christoffer.dall@linaro.org, jiong.wang@arm.com, kvmarm@lists.cs.columbia.edu, linux-arch@vger.kernel.org, marc.zyngier@arm.com, mark.rutland@arm.com, suzuki.poulose@arm.com, will.deacon@arm.com Subject: [RFC 5/9] arm64: Don't trap host pointer auth use to EL2 Date: Mon, 3 Apr 2017 16:19:21 +0100 Message-Id: <1491232765-32501-6-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1491232765-32501-1-git-send-email-mark.rutland@arm.com> References: <1491232765-32501-1-git-send-email-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2403 Lines: 72 To allow EL0 (and/or EL1) to use pointer authentication functionality, we must ensure that pointer authentication instructions and accesses to pointer authentication keys are not trapped to EL2 (where we will not be able to handle them). This patch ensures that HCR_EL2 is configured appropriately when the kernel is booted at EL2. For non-VHE kernels we set HCR_EL2.{API,APK}, ensuring that EL1 can access keys and permit EL0 use of instructions. For VHE kernels, EL2 access is controlled by EL3, and we need not set anything. This does not enable support for KVM guests, since KVM manages HCR_EL2 itself. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Christoffer Dall Cc: Marc Zyngier Cc: Will Deacon Cc: kvmarm@lists.cs.columbia.edu --- arch/arm64/include/asm/kvm_arm.h | 2 ++ arch/arm64/kernel/head.S | 19 +++++++++++++++++-- 2 files changed, 19 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index 6e99978..d8a1271 100644 --- a/arch/arm64/include/asm/kvm_arm.h +++ b/arch/arm64/include/asm/kvm_arm.h @@ -23,6 +23,8 @@ #include /* Hyp Configuration Register (HCR) bits */ +#define HCR_API (UL(1) << 41) +#define HCR_APK (UL(1) << 40) #define HCR_E2H (UL(1) << 34) #define HCR_ID (UL(1) << 33) #define HCR_CD (UL(1) << 32) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 0b13748..9f3f49f 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -562,10 +562,25 @@ CPU_LE( bic x0, x0, #(1 << 25) ) // Clear the EE bit for EL2 /* Hyp configuration. */ mov x0, #HCR_RW // 64-bit EL1 - cbz x2, set_hcr + cbz x2, 1f orr x0, x0, #HCR_TGE // Enable Host Extensions orr x0, x0, #HCR_E2H -set_hcr: +1: +#ifdef CONFIG_ARM64_POINTER_AUTHENTICATION + /* + * Disable pointer authentication traps to EL2. The HCR_EL2.{APK,API} + * bits exist iff at least one authentication mechanism is implemented. + */ + mrs x1, id_aa64isar1_el1 + mov_q x3, ((0xf << ID_AA64ISAR1_GPI_SHIFT) | \ + (0xf << ID_AA64ISAR1_GPA_SHIFT) | \ + (0xf << ID_AA64ISAR1_API_SHIFT) | \ + (0xf << ID_AA64ISAR1_APA_SHIFT)) + and x1, x1, x3 + cbz x1, 1f + orr x0, x0, #(HCR_APK | HCR_API) +1: +#endif msr hcr_el2, x0 isb -- 1.9.1