linux-kernel - [tip:x86/asm] x86: Default to vsyscall=emulate

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Date:	Mon, 5 Dec 2011 05:24:45 -0800
From:	tip-bot for Andy Lutomirski <luto@...capital.net>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	torvalds@...ux-foundation.org, bunk@...sta.de, luto@...capital.net,
	richard.weinberger@...il.com, tglx@...utronix.de,
	hpa@...ux.intel.com, mingo@...e.hu
Subject: [tip:x86/asm] x86: Default to vsyscall=emulate

Commit-ID:  2e57ae0515124af45dd889bfbd4840fd40fcc07d
Gitweb:     http://git.kernel.org/tip/2e57ae0515124af45dd889bfbd4840fd40fcc07d
Author:     Andy Lutomirski <luto@...capital.net>
AuthorDate: Mon, 7 Nov 2011 16:33:41 -0800
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Mon, 5 Dec 2011 12:17:29 +0100

x86: Default to vsyscall=emulate

This essentially reverts:

  2b666859ec32: x86: Default to vsyscall=native for now

The ABI breakage should now be fixed by:

 commit 48c4206f5b02f28c4c78a1f5b491d3772fb64fb9
 Author: Andy Lutomirski <luto@....edu>
 Date:   Thu Oct 20 08:48:19 2011 -0700

    x86-64: Set siginfo and context on vsyscall emulation faults

Signed-off-by: Andy Lutomirski <luto@...capital.net>
Cc: richard -rw- weinberger <richard.weinberger@...il.com>
Cc: Adrian Bunk <bunk@...sta.de>
Cc: H. Peter Anvin <hpa@...ux.intel.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Link: http://lkml.kernel.org/r/93154af3b2b6d208906ae02d80d92cf60c6fa94f.1320712291.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 Documentation/kernel-parameters.txt |    7 +++----
 arch/x86/kernel/vsyscall_64.c       |    2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a0c5c5f..ce7fc8b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2750,11 +2750,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			functions are at fixed addresses, they make nice
 			targets for exploits that can control RIP.
 
-			emulate     Vsyscalls turn into traps and are emulated
-			            reasonably safely.
+			emulate     [default] Vsyscalls turn into traps and are
+			            emulated reasonably safely.
 
-			native      [default] Vsyscalls are native syscall
-			            instructions.
+			native      Vsyscalls are native syscall instructions.
 			            This is a little bit faster than trapping
 			            and makes a few dynamic recompilers work
 			            better than they would in emulation mode.
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 8084bec..b07ba93 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -57,7 +57,7 @@ DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
 	.lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock),
 };
 
-static enum { EMULATE, NATIVE, NONE } vsyscall_mode = NATIVE;
+static enum { EMULATE, NATIVE, NONE } vsyscall_mode = EMULATE;
 
 static int __init vsyscall_setup(char *str)
 {
--
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