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From: Mark Brown <broonie@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: "Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Paul Elliott" <paul.elliott@arm.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Yu-cheng Yu" <yu-cheng.yu@intel.com>,
	"Amit Kachhap" <amit.kachhap@arm.com>,
	"Vincenzo Frascino" <vincenzo.frascino@arm.com>,
	"Marc Zyngier" <maz@kernel.org>,
	"Eugene Syromiatnikov" <esyr@redhat.com>,
	"Szabolcs Nagy" <szabolcs.nagy@arm.com>,
	"H . J . Lu " <hjl.tools@gmail.com>,
	"Andrew Jones" <drjones@redhat.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Arnd Bergmann" <arnd@arndb.de>, "Jann Horn" <jannh@google.com>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"Kristina Martšenko" <kristina.martsenko@arm.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Florian Weimer" <fweimer@redhat.com>,
	"Sudakshina Das" <sudi.das@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-fsdevel@vger.kernel.org,
	"Dave Martin" <Dave.Martin@arm.com>,
	"Mark Brown" <broonie@kernel.org>
Subject: [PATCH v9 13/13] arm64: BTI: Add Kconfig entry for userspace BTI
Date: Wed, 11 Mar 2020 19:26:08 +0000	[thread overview]
Message-ID: <20200311192608.40095-14-broonie@kernel.org> (raw)
In-Reply-To: <20200311192608.40095-1-broonie@kernel.org>

From: Dave Martin <Dave.Martin@arm.com>

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 <Dave.Martin@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 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


  parent reply	other threads:[~2020-03-11 19:33 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-11 19:25 [PATCH v9 00/13] arm64: Branch Target Identification support Mark Brown
2020-03-11 19:25 ` [PATCH v9 01/13] ELF: UAPI and Kconfig additions for ELF program properties Mark Brown
2020-03-11 19:25 ` [PATCH v9 02/13] ELF: Add ELF program property parsing support Mark Brown
2020-03-12 23:59   ` Kees Cook
2020-03-13 11:55     ` Mark Brown
2020-03-11 19:25 ` [PATCH v9 03/13] arm64: Basic Branch Target Identification support Mark Brown
2020-03-11 19:25 ` [PATCH v9 04/13] elf: Allow arch to tweak initial mmap prot flags Mark Brown
2020-03-11 19:26 ` [PATCH v9 05/13] arm64: elf: Enable BTI at exec based on ELF program properties Mark Brown
2020-03-11 19:26 ` [PATCH v9 06/13] arm64: BTI: Decode BYTPE bits when printing PSTATE Mark Brown
2020-03-11 19:26 ` [PATCH v9 07/13] arm64: unify native/compat instruction skipping Mark Brown
2020-03-11 19:26 ` [PATCH v9 08/13] arm64: traps: Shuffle code to eliminate forward declarations Mark Brown
2020-03-14 11:18   ` Catalin Marinas
2020-03-11 19:26 ` [PATCH v9 09/13] arm64: BTI: Reset BTYPE when skipping emulated instructions Mark Brown
2020-03-11 19:26 ` [PATCH v9 10/13] KVM: " Mark Brown
2020-03-11 19:26 ` [PATCH v9 11/13] arm64: mm: Display guarded pages in ptdump Mark Brown
2020-03-11 19:26 ` [PATCH v9 12/13] mm: smaps: Report arm64 guarded pages in smaps Mark Brown
2020-03-13  0:00   ` Kees Cook
2020-03-11 19:26 ` Mark Brown [this message]
2020-03-13  0:01   ` [PATCH v9 13/13] arm64: BTI: Add Kconfig entry for userspace BTI Kees Cook

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