linux-kernel - [tip:mm/pkeys] x86/mm/pkeys: Add new 'PF

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Message-ID: <tip-b3ecd51559ae7a8f40b10443773b9cd0e6a50f5e@git.kernel.org>
Date:	Thu, 18 Feb 2016 12:18:41 -0800
From:	tip-bot for Dave Hansen <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...nel.org, dave.hansen@...ux.intel.com,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	riel@...hat.com, tglx@...utronix.de, dvlasenk@...hat.com,
	peterz@...radead.org, torvalds@...ux-foundation.org, bp@...en8.de,
	brgerst@...il.com, hpa@...or.com, dave@...1.net,
	luto@...capital.net
Subject: [tip:mm/pkeys] x86/mm/pkeys: Add new 'PF_PK'
  page fault error code bit

Commit-ID:  b3ecd51559ae7a8f40b10443773b9cd0e6a50f5e
Gitweb:     http://git.kernel.org/tip/b3ecd51559ae7a8f40b10443773b9cd0e6a50f5e
Author:     Dave Hansen <dave.hansen@...ux.intel.com>
AuthorDate: Fri, 12 Feb 2016 13:02:07 -0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 18 Feb 2016 09:31:50 +0100

x86/mm/pkeys: Add new 'PF_PK' page fault error code bit

Note: "PK" is how the Intel SDM refers to this bit, so we also
use that nomenclature.

This only defines the bit, it does not plumb it anywhere to be
handled.

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave@...1.net>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: linux-mm@...ck.org
Link: http://lkml.kernel.org/r/20160212210207.DA7B43E6@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/mm/fault.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index eef44d9..9f72f9c 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -33,6 +33,7 @@
  *   bit 2 ==	 0: kernel-mode access	1: user-mode access
  *   bit 3 ==				1: use of reserved bit detected
  *   bit 4 ==				1: fault was an instruction fetch
+ *   bit 5 ==				1: protection keys block access
  */
 enum x86_pf_error_code {
 
@@ -41,6 +42,7 @@ enum x86_pf_error_code {
 	PF_USER		=		1 << 2,
 	PF_RSVD		=		1 << 3,
 	PF_INSTR	=		1 << 4,
+	PF_PK		=		1 << 5,
 };
 
 /*
@@ -916,6 +918,12 @@ static int spurious_fault_check(unsigned long error_code, pte_t *pte)
 
 	if ((error_code & PF_INSTR) && !pte_exec(*pte))
 		return 0;
+	/*
+	 * Note: We do not do lazy flushing on protection key
+	 * changes, so no spurious fault will ever set PF_PK.
+	 */
+	if ((error_code & PF_PK))
+		return 1;
 
 	return 1;
 }