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Subject: Re: [PATCH 2/3] x86/mm: introduce __PAGE_KERNEL_GLOBAL
References: <20180215132053.6C9B48C8@viggo.jf.intel.com>
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From: Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <9f77b568-d86c-47db-f7a3-ddb931f33af0@linux.intel.com>
Date: Fri, 16 Feb 2018 12:00:38 -0800
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Sender: owner-linux-mm@kvack.org
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To: Nadav Amit <nadav.amit@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>, "open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>, Andy Lutomirski <luto@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, keescook@google.com, Hugh Dickins <hughd@google.com>, Juergen Gross <jgross@suse.com>, x86@kernel.org

On 02/16/2018 11:54 AM, Nadav Amit wrote:
>> But I don't really want to hide that gunk in a macro like that.  It
>> might make more sense as a static inline.  I'll give that a shot and resent.
> Since determining whether PTI is on is done in several places in the kernel,
> maybe there should a single function to determine whether PTI is on,
> something like:
> 
> static inline bool is_pti_on(void)
> {
> 	return IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) && 
> 		static_cpu_has(X86_FEATURE_PTI);
> }

We should be able to do it with disabled-features.h and the X86_FEATURE
bit.  I'll look into it.

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