x86, bitops: Correct the assembly constraints to testing bitops

In checkin:

0c44c2d0f459 x86: Use asm goto to implement better modify_and_test() functions

the various functions which do modify and test were unified and
optimized using "asm goto".  However, this change missed the detail
that the bitops require an "Ir" constraint rather than an "er"
constraint ("I" = integer constant from 0-31, "e" = signed 32-bit
integer constant).  This would cause code to miscompile if these
functions were used on constant bit positions 32-255 and the build to
fail if used on constant bit positions above 255.

Add the constraints as a parameter to the GEN_BINARY_RMWcc() macro to
avoid this problem.

Reported-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/529E8719.4070202@zytor.com

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/x86/include/asm/local.h b/arch/x86/include/asm/local.h
index 5b23e605e70..4ad6560847b 100644
--- a/arch/x86/include/asm/local.h
+++ b/arch/x86/include/asm/local.h
@@ -52,7 +52,7 @@ static inline void local_sub(long i, local_t *l)
  */
 static inline int local_sub_and_test(long i, local_t *l)
 {
-	GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, i, "%0", "e");
+	GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, "er", i, "%0", "e");
 }
 
 /**
@@ -92,7 +92,7 @@ static inline int local_inc_and_test(local_t *l)
  */
 static inline int local_add_negative(long i, local_t *l)
 {
-	GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, i, "%0", "s");
+	GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, "er", i, "%0", "s");
 }
 
 /**