[tip:mm/pkeys] x86/mm/pkeys: Add Kconfig prompt to existing config option

[tip-bot for Dave Hansen]

Commit-ID:  284244a9876225eb73102aff41d4492f65cb2868
Gitweb:     http://git.kernel.org/tip/284244a9876225eb73102aff41d4492f65cb2868
Author:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
AuthorDate: Fri, 12 Feb 2016 13:02:28 -0800
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 18 Feb 2016 19:46:30 +0100

x86/mm/pkeys: Add Kconfig prompt to existing config option

I don't have a strong opinion on whether we need this or not.
Protection Keys has relatively little code associated with it,
and it is not a heavyweight feature to keep enabled.  However,
I can imagine that folks would still appreciate being able to
disable it.

Here's the option if folks want it.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Link: http://lkml.kernel.org/r/20160212210228.7E79386C@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/Kconfig | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fb2ebeb..b875434 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1716,8 +1716,18 @@ config X86_INTEL_MPX
 	  If unsure, say N.
 
 config X86_INTEL_MEMORY_PROTECTION_KEYS
+	prompt "Intel Memory Protection Keys"
 	def_bool y
+	# Note: only available in 64-bit mode
 	depends on CPU_SUP_INTEL && X86_64
+	---help---
+	  Memory Protection Keys provides a mechanism for enforcing
+	  page-based protections, but without requiring modification of the
+	  page tables when an application changes protection domains.
+
+	  For details, see Documentation/x86/protection-keys.txt
+
+	  If unsure, say y.
 
 config EFI
 	bool "EFI runtime service support"