x32: Make sure TS_COMPAT is cleared for x32 tasks

If a process has a non-x32 ia32 personality and changes to x32, the
process would keep its TS_COMPAT flag. x32 uses the presence of the
x32 flag on a syscall to determine compat status, so make sure
TS_COMPAT is cleared.

Signed-off-by: Bobby Powers <bobbypowers@gmail.com>
Link: http://lkml.kernel.org/r/1330230338-25077-1-git-send-email-bobbypowers@gmail.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Author: bpowers

arch/x86/kernel/process_64.c

@@ -540,6 +540,9 @@ void set_personality_ia32(bool x32)
 		clear_thread_flag(TIF_IA32);
 		set_thread_flag(TIF_X32);
 		current->personality &= ~READ_IMPLIES_EXEC;
+		/* is_compat_task() uses the presence of the x32
+		   syscall bit flag to determine compat status */
+		current_thread_info()->status &= ~TS_COMPAT;
 	} else {
 		set_thread_flag(TIF_IA32);
 		clear_thread_flag(TIF_X32);