[PATCH] x86-64: Use different constraint for gcc < 4.1 in bitops.h

+m is really correct for a RMW instruction, but some older gccs
error out. I finally gave in and ifdefed it.

This fixes compilation errors with some compiler version.

Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 20 insertions, 14 deletions

diff --git a/include/asm-x86_64/bitops.h b/include/asm-x86_64/bitops.h
index 5b535eaf5309..8da9609070f4 100644
--- a/include/asm-x86_64/bitops.h
+++ b/include/asm-x86_64/bitops.h
@@ -7,7 +7,13 @@
 
 #include <asm/alternative.h>
 
-#define ADDR (*(volatile long *) addr)
+#if __GNUC__ < 4 || __GNUC_MINOR__ < 1
+/* Technically wrong, but this avoids compilation errors on some gcc
+   versions. */
+#define ADDR "=m" (*(volatile long *) addr)
+#else
+#define ADDR "+m" (*(volatile long *) addr)
+#endif
 
 /**
  * set_bit - Atomically set a bit in memory
@@ -23,7 +29,7 @@ static __inline__ void set_bit(int nr, volatile void * addr)
 {
         __asm__ __volatile__( LOCK_PREFIX
                 "btsl %1,%0"
-                :"+m" (ADDR)
+                :ADDR
                 :"dIr" (nr) : "memory");
 }
 
@@ -40,7 +46,7 @@ static __inline__ void __set_bit(int nr, volatile void * addr)
 {
         __asm__ volatile(
                 "btsl %1,%0"
-                :"+m" (ADDR)
+                :ADDR
                 :"dIr" (nr) : "memory");
 }
 
@@ -58,7 +64,7 @@ static __inline__ void clear_bit(int nr, volatile void * addr)
 {
         __asm__ __volatile__( LOCK_PREFIX
                 "btrl %1,%0"
-                :"+m" (ADDR)
+                :ADDR
                 :"dIr" (nr));
 }
 
@@ -66,7 +72,7 @@ static __inline__ void __clear_bit(int nr, volatile void * addr)
 {
         __asm__ __volatile__(
                 "btrl %1,%0"
-                :"+m" (ADDR)
+                :ADDR
                 :"dIr" (nr));
 }
 
@@ -86,7 +92,7 @@ static __inline__ void __change_bit(int nr, volatile void * addr)
 {
         __asm__ __volatile__(
                 "btcl %1,%0"
-                :"+m" (ADDR)
+                :ADDR
                 :"dIr" (nr));
 }
 
@@ -103,7 +109,7 @@ static __inline__ void change_bit(int nr, volatile void * addr)
 {
         __asm__ __volatile__( LOCK_PREFIX
                 "btcl %1,%0"
-                :"+m" (ADDR)
+                :ADDR
                 :"dIr" (nr));
 }
 
@@ -121,7 +127,7 @@ static __inline__ int test_and_set_bit(int nr, volatile void * addr)
 
         __asm__ __volatile__( LOCK_PREFIX
                 "btsl %2,%1\n\tsbbl %0,%0"
-                :"=r" (oldbit),"+m" (ADDR)
+                :"=r" (oldbit),ADDR
                 :"dIr" (nr) : "memory");
         return oldbit;
 }
@@ -141,7 +147,7 @@ static __inline__ int __test_and_set_bit(int nr, volatile void * addr)
 
         __asm__(
                 "btsl %2,%1\n\tsbbl %0,%0"
-                :"=r" (oldbit),"+m" (ADDR)
+                :"=r" (oldbit),ADDR
                 :"dIr" (nr));
         return oldbit;
 }
@@ -160,7 +166,7 @@ static __inline__ int test_and_clear_bit(int nr, volatile void * addr)
 
         __asm__ __volatile__( LOCK_PREFIX
                 "btrl %2,%1\n\tsbbl %0,%0"
-                :"=r" (oldbit),"+m" (ADDR)
+                :"=r" (oldbit),ADDR
                 :"dIr" (nr) : "memory");
         return oldbit;
 }
@@ -180,7 +186,7 @@ static __inline__ int __test_and_clear_bit(int nr, volatile void * addr)
 
         __asm__(
                 "btrl %2,%1\n\tsbbl %0,%0"
-                :"=r" (oldbit),"+m" (ADDR)
+                :"=r" (oldbit),ADDR
                 :"dIr" (nr));
         return oldbit;
 }
@@ -192,7 +198,7 @@ static __inline__ int __test_and_change_bit(int nr, volatile void * addr)
 
         __asm__ __volatile__(
                 "btcl %2,%1\n\tsbbl %0,%0"
-                :"=r" (oldbit),"+m" (ADDR)
+                :"=r" (oldbit),ADDR
                 :"dIr" (nr) : "memory");
         return oldbit;
 }
@@ -211,7 +217,7 @@ static __inline__ int test_and_change_bit(int nr, volatile void * addr)
 
         __asm__ __volatile__( LOCK_PREFIX
                 "btcl %2,%1\n\tsbbl %0,%0"
-                :"=r" (oldbit),"+m" (ADDR)
+                :"=r" (oldbit),ADDR
                 :"dIr" (nr) : "memory");
         return oldbit;
 }
@@ -237,7 +243,7 @@ static __inline__ int variable_test_bit(int nr, volatile const void * addr)
         __asm__ __volatile__(
                 "btl %2,%1\n\tsbbl %0,%0"
                 :"=r" (oldbit)
-                :"m" (ADDR),"dIr" (nr));
+                :"m" (*(volatile long *)addr),"dIr" (nr));
         return oldbit;
 }