[ARM] 3759/2: Remove uses of %?

Patch from Daniel Jacobowitz

The ARM kernel has several uses of asm("foo%?").  %? is a GCC internal
modifier used to output conditional execution predicates.  However, no
version of GCC supports conditionalizing asm statements.  GCC 4.2 will
correctly expand %? to the empty string in user asms.  Earlier versions may
reuse the condition from the previous instruction.  In 'if (foo) asm
("bar%?");' this is somewhat likely to be right... but not reliable.

So, the only safe thing to do is to remove the uses of %?.  I believe
the tlbflush.h occurances were supposed to be removed before, based
on the comment about %? not working at the top of that file.

Old versions of GCC could omit branches around user asms if the asm didn't
mark the condition codes as clobbered.  This problem hasn't been seen on any
recent (3.x or 4.x) GCC, but it could theoretically happen.  So, where
%? was removed a cc clobber was added.

Signed-off-by: Daniel Jacobowitz <dan@codesourcery.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index aeeed806f991..bede380c07a9 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -191,7 +191,7 @@ void show_stack(struct task_struct *tsk, unsigned long *sp)
 	if (tsk != current)
 		fp = thread_saved_fp(tsk);
 	else
-		asm("mov%? %0, fp" : "=r" (fp));
+		asm("mov %0, fp" : "=r" (fp) : : "cc");
 
 	c_backtrace(fp, 0x10);
 	barrier();