From: Catalin Marinas <catalin.marinas@arm.com>
To: Mark Brown <broonie@kernel.org>
Cc: "Paul Elliott" <paul.elliott@arm.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Andrew Jones" <drjones@redhat.com>,
"Amit Kachhap" <amit.kachhap@arm.com>,
"Vincenzo Frascino" <vincenzo.frascino@arm.com>,
"Will Deacon" <will@kernel.org>,
linux-arch@vger.kernel.org, "Marc Zyngier" <maz@kernel.org>,
"Eugene Syromiatnikov" <esyr@redhat.com>,
"Szabolcs Nagy" <szabolcs.nagy@arm.com>,
"Dave Martin" <Dave.Martin@arm.com>,
"H . J . Lu " <hjl.tools@gmail.com>,
"Yu-cheng Yu" <yu-cheng.yu@intel.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>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Thomas Gleixner" <tglx@linutronix.de>,
linux-arm-kernel@lists.infradead.org,
"Florian Weimer" <fweimer@redhat.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
"Sudakshina Das" <sudi.das@arm.com>
Subject: Re: [PATCH v8 03/11] arm64: Basic Branch Target Identification support
Date: Wed, 11 Mar 2020 16:31:03 +0000 [thread overview]
Message-ID: <20200311163103.GL3216816@arrakis.emea.arm.com> (raw)
In-Reply-To: <20200227174417.23722-4-broonie@kernel.org>
On Thu, Feb 27, 2020 at 05:44:09PM +0000, Mark Brown wrote:
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 0b30e884e088..e37f4f07b990 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1519,6 +1519,28 @@ 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.
To keep the series bisectable, I'd move the Kconfig into a separate
patch towards the end. It looks like the feature is only partially
supported after patch 3, so let's not advertise it here.
--
Catalin
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next prev parent reply other threads:[~2020-03-11 16:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-27 17:44 [PATCH v8 00/11] arm64: Branch Target Identification support Mark Brown
2020-02-27 17:44 ` [PATCH v8 01/11] ELF: UAPI and Kconfig additions for ELF program properties Mark Brown
2020-02-27 17:44 ` [PATCH v8 02/11] ELF: Add ELF program property parsing support Mark Brown
2020-02-27 17:44 ` [PATCH v8 03/11] arm64: Basic Branch Target Identification support Mark Brown
2020-03-11 16:31 ` Catalin Marinas [this message]
2020-02-27 17:44 ` [PATCH v8 04/11] elf: Allow arch to tweak initial mmap prot flags Mark Brown
2020-02-27 17:44 ` [PATCH v8 05/11] arm64: elf: Enable BTI at exec based on ELF program properties Mark Brown
2020-02-27 17:44 ` [PATCH v8 06/11] arm64: BTI: Decode BYTPE bits when printing PSTATE Mark Brown
2020-02-27 17:44 ` [PATCH v8 07/11] arm64: unify native/compat instruction skipping Mark Brown
2020-02-27 17:44 ` [PATCH v8 08/11] arm64: traps: Shuffle code to eliminate forward declarations Mark Brown
2020-02-27 17:44 ` [PATCH v8 09/11] arm64: BTI: Reset BTYPE when skipping emulated instructions Mark Brown
2020-02-27 17:44 ` [PATCH v8 10/11] KVM: " Mark Brown
2020-02-27 17:44 ` [PATCH v8 11/11] arm64: mm: Display guarded pages in ptdump Mark Brown
2020-02-28 1:35 ` [PATCH v8 00/11] arm64: Branch Target Identification support Richard Henderson
2020-03-11 19:15 ` Mark Brown
2020-03-06 10:21 ` Catalin Marinas
2020-03-06 10:27 ` Catalin Marinas
2020-03-09 21:05 ` Mark Brown
2020-03-10 12:42 ` Mark Brown
2020-03-11 16:28 ` Catalin Marinas
2020-03-11 17:25 ` Mark Brown
2020-03-12 18:42 ` Catalin Marinas
2020-03-13 12:59 ` Mark Brown
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