From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: [PATCH v10 13/13] arm64: BTI: Add Kconfig entry for userspace BTI Date: Mon, 16 Mar 2020 16:50:55 +0000 Message-ID: <20200316165055.31179-14-broonie@kernel.org> References: <20200316165055.31179-1-broonie@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200316165055.31179-1-broonie@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: Catalin Marinas , Will Deacon Cc: Alexander Viro , Paul Elliott , Peter Zijlstra , Yu-cheng Yu , Amit Kachhap , Vincenzo Frascino , Marc Zyngier , Eugene Syromiatnikov , Szabolcs Nagy , "H . J . Lu " , Andrew Jones , Kees Cook , Arnd Bergmann , Jann Horn , Richard Henderson , =?UTF-8?q?Kristina=20Mart=C5=A1enko?= , Thomas Gleixner , Florian Weimer , Sudakshina Das , linux-a List-Id: linux-arch.vger.kernel.org From: Dave Martin Now that the code for userspace BTI support is in the kernel add the Kconfig entry so that it can be built and used. [Split out of "arm64: Basic Branch Target Identification support" -- broonie] Signed-off-by: Dave Martin Reviewed-by: Kees Cook Signed-off-by: Mark Brown --- arch/arm64/Kconfig | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 8a15bc68dadd..d65d226a77ec 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1522,6 +1522,28 @@ endmenu menu "ARMv8.5 architectural features" +config ARM64_BTI + bool "Branch Target Identification support" + default y + help + Branch Target Identification (part of the ARMv8.5 Extensions) + provides a mechanism to limit the set of locations to which computed + branch instructions such as BR or BLR can jump. + + To make use of BTI on CPUs that support it, say Y. + + BTI is intended to provide complementary protection to other control + flow integrity protection mechanisms, such as the Pointer + authentication mechanism provided as part of the ARMv8.3 Extensions. + For this reason, it does not make sense to enable this option without + also enabling support for pointer authentication. Thus, when + enabling this option you should also select ARM64_PTR_AUTH=y. + + Userspace binaries must also be specifically compiled to make use of + this mechanism. If you say N here or the hardware does not support + BTI, such binaries can still run, but you get no additional + enforcement of branch destinations. + config ARM64_E0PD bool "Enable support for E0PD" default y -- 2.20.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.110.172]:52372 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732296AbgCPQv1 (ORCPT ); Mon, 16 Mar 2020 12:51:27 -0400 From: Mark Brown Subject: [PATCH v10 13/13] arm64: BTI: Add Kconfig entry for userspace BTI Date: Mon, 16 Mar 2020 16:50:55 +0000 Message-ID: <20200316165055.31179-14-broonie@kernel.org> In-Reply-To: <20200316165055.31179-1-broonie@kernel.org> References: <20200316165055.31179-1-broonie@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Catalin Marinas , Will Deacon Cc: Alexander Viro , Paul Elliott , Peter Zijlstra , Yu-cheng Yu , Amit Kachhap , Vincenzo Frascino , Marc Zyngier , Eugene Syromiatnikov , Szabolcs Nagy , "H . J . Lu " , Andrew Jones , Kees Cook , Arnd Bergmann , Jann Horn , Richard Henderson , =?UTF-8?q?Kristina=20Mart=C5=A1enko?= , Thomas Gleixner , Florian Weimer , Sudakshina Das , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, Dave Martin , Mark Brown Message-ID: <20200316165055.QAgLE14Zm8stobCV0Rqvttx9Hp6tgBc4R5q4V1jjH_8@z> From: Dave Martin Now that the code for userspace BTI support is in the kernel add the Kconfig entry so that it can be built and used. [Split out of "arm64: Basic Branch Target Identification support" -- broonie] Signed-off-by: Dave Martin Reviewed-by: Kees Cook Signed-off-by: Mark Brown --- arch/arm64/Kconfig | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 8a15bc68dadd..d65d226a77ec 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1522,6 +1522,28 @@ endmenu menu "ARMv8.5 architectural features" +config ARM64_BTI + bool "Branch Target Identification support" + default y + help + Branch Target Identification (part of the ARMv8.5 Extensions) + provides a mechanism to limit the set of locations to which computed + branch instructions such as BR or BLR can jump. + + To make use of BTI on CPUs that support it, say Y. + + BTI is intended to provide complementary protection to other control + flow integrity protection mechanisms, such as the Pointer + authentication mechanism provided as part of the ARMv8.3 Extensions. + For this reason, it does not make sense to enable this option without + also enabling support for pointer authentication. Thus, when + enabling this option you should also select ARM64_PTR_AUTH=y. + + Userspace binaries must also be specifically compiled to make use of + this mechanism. If you say N here or the hardware does not support + BTI, such binaries can still run, but you get no additional + enforcement of branch destinations. + config ARM64_E0PD bool "Enable support for E0PD" default y -- 2.20.1