[PATCH 4.14 076/167] x86/speculation: Fix up array_index_nospec_mask() asm constraint

Greg Kroah-Hartman
2018-02-21T12:48:07Z

From: Dan Williams <dan.j.williams@intel.com>

commit be3233fbfcb8f5acb6e3bcd0895c3ef9e100d470 upstream.

Allow the compiler to handle @size as an immediate value or memory
directly rather than allocating a register.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/151797010204.1289.1510000292250184993.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/include/asm/barrier.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -40,7 +40,7 @@ static inline unsigned long array_index_

asm ("cmp %1,%2; sbb %0,%0;"
:"=r" (mask)
- :"r"(size),"r" (index)
+ :"g"(size),"r" (index)
:"cc");
return mask;
}