[tip:x86/pti] x86/speculation: Fix up array_index_nospec_mask() asm constraint

[tip-bot for Dan Williams <tipbot@zytor.com>]

Commit-ID:  be3233fbfcb8f5acb6e3bcd0895c3ef9e100d470
Gitweb:     https://git.kernel.org/tip/be3233fbfcb8f5acb6e3bcd0895c3ef9e100d470
Author:     Dan Williams <dan.j.williams@intel.com>
AuthorDate: Tue, 6 Feb 2018 18:22:40 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 15 Feb 2018 01:15:50 +0100

x86/speculation: Fix up array_index_nospec_mask() asm constraint

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

diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index 30d4061..e1259f0 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -40,7 +40,7 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
 
 	asm ("cmp %1,%2; sbb %0,%0;"
 			:"=r" (mask)
-			:"r"(size),"r" (index)
+			:"g"(size),"r" (index)
 			:"cc");
 	return mask;
 }