x86: Default to vsyscall=native for now

This UML breakage:

  linux-2.6.30.1[3800] vsyscall fault (exploit attempt?) ip:ffffffffff600000 cs:33 sp:7fbfb9c498 ax:ffffffffff600000 si:0 di:606790
  linux-2.6.30.1[3856] vsyscall fault (exploit attempt?) ip:ffffffffff600000 cs:33 sp:7fbfb13168 ax:ffffffffff600000 si:0 di:606790

Is caused by commit 3ae36655 ("x86-64: Rework vsyscall emulation and add
vsyscall= parameter") - the vsyscall emulation code is not fully cooked
yet as UML relies on some rather fragile SIGSEGV semantics.

Linus suggested in https://lkml.org/lkml/2011/8/9/376 to default
to vsyscall=native for now, this patch implements that.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Andrew Lutomirski <luto@mit.edu>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/20111005214047.GE14406@localhost.pp.htv.fi
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 18ae83dd1cd7..b56c65de384d 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -56,7 +56,7 @@ DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
         .lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock),
 };
 
-static enum { EMULATE, NATIVE, NONE } vsyscall_mode = EMULATE;
+static enum { EMULATE, NATIVE, NONE } vsyscall_mode = NATIVE;
 
 static int __init vsyscall_setup(char *str)
 {