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Subject: Re: [PATCH 1/7] x86/cet: Add Kconfig option for user-mode Indirect
 Branch Tracking
To:     Yu-cheng Yu <yu-cheng.yu@intel.com>, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H.J. Lu" <hjl.tools@gmail.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Jonathan Corbet <corbet@lwn.net>,
        Oleg Nesterov <oleg@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
        Mike Kravetz <mike.kravetz@oracle.com>
References: <20180607143855.3681-1-yu-cheng.yu@intel.com>
 <20180607143855.3681-2-yu-cheng.yu@intel.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <9c99f892-8965-8b08-4a80-506b48c2205d@infradead.org>
Date:   Thu, 7 Jun 2018 09:43:49 -0700
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On 06/07/2018 07:38 AM, Yu-cheng Yu wrote:
> The user-mode indirect branch tracking support is done mostly by
> GCC to insert ENDBR64/ENDBR32 instructions at branch targets.
> The kernel provides CPUID enumeration, feature MSR setup and
> the allocation of legacy bitmap.
> 
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> ---
>  arch/x86/Kconfig | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 24339a5299da..27bfbd137fbe 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1953,6 +1953,18 @@ config X86_INTEL_SHADOW_STACK_USER
>  
>  	  If unsure, say y.
>  
> +config X86_INTEL_BRANCH_TRACKING_USER
> +	prompt "Intel Indirect Branch Tracking for user-mode"
> +	def_bool n
> +	depends on CPU_SUP_INTEL && X86_64
> +	select X86_INTEL_CET
> +	select ARCH_HAS_PROGRAM_PROPERTIES
> +	---help---
> +	  Indirect Branch Tracking provides hardware protection against 	
> +	  oriented programing attacks.

	           programming

and please just move the return/jmp parts to the next line also:

	                                             protection against
	  return-/jmp-oriented programming attacks.

> +
> +	  If unsure, say y
> +
>  config EFI
>  	bool "EFI runtime service support"
>  	depends on ACPI
> 


-- 
~Randy