1 files changed, 57 insertions, 43 deletions

diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index ca7517d33776..d1e41b0f9b60 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -41,6 +41,7 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/lockdep.h>
+#include <asm/asm.h>
 
 struct rwsem_waiter;
 
@@ -55,17 +56,28 @@ extern asmregparm struct rw_semaphore *
 
 /*
  * the semaphore definition
+ *
+ * The bias values and the counter type limits the number of
+ * potential readers/writers to 32767 for 32 bits and 2147483647
+ * for 64 bits.
  */
 
-#define RWSEM_UNLOCKED_VALUE            0x00000000
-#define RWSEM_ACTIVE_BIAS               0x00000001
-#define RWSEM_ACTIVE_MASK               0x0000ffff
-#define RWSEM_WAITING_BIAS              (-0x00010000)
+#ifdef CONFIG_X86_64
+# define RWSEM_ACTIVE_MASK              0xffffffffL
+#else
+# define RWSEM_ACTIVE_MASK              0x0000ffffL
+#endif
+
+#define RWSEM_UNLOCKED_VALUE            0x00000000L
+#define RWSEM_ACTIVE_BIAS               0x00000001L
+#define RWSEM_WAITING_BIAS              (-RWSEM_ACTIVE_MASK-1)
 #define RWSEM_ACTIVE_READ_BIAS          RWSEM_ACTIVE_BIAS
 #define RWSEM_ACTIVE_WRITE_BIAS         (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
 
+typedef signed long rwsem_count_t;
+
 struct rw_semaphore {
-        signed long             count;
+        rwsem_count_t           count;
         spinlock_t              wait_lock;
         struct list_head        wait_list;
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -105,8 +117,8 @@ do {								\
 static inline void __down_read(struct rw_semaphore *sem)
 {
         asm volatile("# beginning down_read\n\t"
-                     LOCK_PREFIX "  incl      (%%eax)\n\t"
-                     /* adds 0x00000001, returns the old value */
+                     LOCK_PREFIX _ASM_INC "(%1)\n\t"
+                     /* adds 0x00000001 */
                      "  jns        1f\n"
                      "  call call_rwsem_down_read_failed\n"
                      "1:\n\t"
@@ -121,14 +133,14 @@ static inline void __down_read(struct rw_semaphore *sem)
  */
 static inline int __down_read_trylock(struct rw_semaphore *sem)
 {
-        __s32 result, tmp;
+        rwsem_count_t result, tmp;
         asm volatile("# beginning __down_read_trylock\n\t"
-                     "  movl      %0,%1\n\t"
+                     "  mov          %0,%1\n\t"
                      "1:\n\t"
-                     "  movl         %1,%2\n\t"
-                     "  addl      %3,%2\n\t"
+                     "  mov          %1,%2\n\t"
+                     "  add          %3,%2\n\t"
                      "  jle          2f\n\t"
-                     LOCK_PREFIX "  cmpxchgl  %2,%0\n\t"
+                     LOCK_PREFIX "  cmpxchg  %2,%0\n\t"
                      "  jnz          1b\n\t"
                      "2:\n\t"
                      "# ending __down_read_trylock\n\t"
@@ -143,20 +155,18 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
  */
 static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
 {
-        int tmp;
-
-        tmp = RWSEM_ACTIVE_WRITE_BIAS;
+        rwsem_count_t tmp;
         asm volatile("# beginning down_write\n\t"
-                     LOCK_PREFIX "  xadd      %%edx,(%%eax)\n\t"
-                     /* subtract 0x0000ffff, returns the old value */
-                     "  testl     %%edx,%%edx\n\t"
+                     LOCK_PREFIX "  xadd      %1,(%2)\n\t"
+                     /* adds 0xffff0001, returns the old value */
+                     "  test      %1,%1\n\t"
                      /* was the count 0 before? */
                      "  jz        1f\n"
                      "  call call_rwsem_down_write_failed\n"
                      "1:\n"
                      "# ending down_write"
                      : "+m" (sem->count), "=d" (tmp)
-                     : "a" (sem), "1" (tmp)
+                     : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS)
                      : "memory", "cc");
 }
 
@@ -170,9 +180,9 @@ static inline void __down_write(struct rw_semaphore *sem)
  */
 static inline int __down_write_trylock(struct rw_semaphore *sem)
 {
-        signed long ret = cmpxchg(&sem->count,
-                                  RWSEM_UNLOCKED_VALUE,
-                                  RWSEM_ACTIVE_WRITE_BIAS);
+        rwsem_count_t ret = cmpxchg(&sem->count,
+                                    RWSEM_UNLOCKED_VALUE,
+                                    RWSEM_ACTIVE_WRITE_BIAS);
         if (ret == RWSEM_UNLOCKED_VALUE)
                 return 1;
         return 0;
@@ -183,16 +193,16 @@ static inline int __down_write_trylock(struct rw_semaphore *sem)
  */
 static inline void __up_read(struct rw_semaphore *sem)
 {
-        __s32 tmp = -RWSEM_ACTIVE_READ_BIAS;
+        rwsem_count_t tmp;
         asm volatile("# beginning __up_read\n\t"
-                     LOCK_PREFIX "  xadd      %%edx,(%%eax)\n\t"
+                     LOCK_PREFIX "  xadd      %1,(%2)\n\t"
                      /* subtracts 1, returns the old value */
                      "  jns        1f\n\t"
-                     "  call call_rwsem_wake\n"
+                     "  call call_rwsem_wake\n" /* expects old value in %edx */
                      "1:\n"
                      "# ending __up_read\n"
                      : "+m" (sem->count), "=d" (tmp)
-                     : "a" (sem), "1" (tmp)
+                     : "a" (sem), "1" (-RWSEM_ACTIVE_READ_BIAS)
                      : "memory", "cc");
 }
 
@@ -201,18 +211,17 @@ static inline void __up_read(struct rw_semaphore *sem)
  */
 static inline void __up_write(struct rw_semaphore *sem)
 {
+        rwsem_count_t tmp;
         asm volatile("# beginning __up_write\n\t"
-                     "  movl      %2,%%edx\n\t"
-                     LOCK_PREFIX "  xaddl     %%edx,(%%eax)\n\t"
-                     /* tries to transition
-                        0xffff0001 -> 0x00000000 */
-                     "  jz       1f\n"
-                     "  call call_rwsem_wake\n"
+                     LOCK_PREFIX "  xadd      %1,(%2)\n\t"
+                     /* subtracts 0xffff0001, returns the old value */
+                     "  jns        1f\n\t"
+                     "  call call_rwsem_wake\n" /* expects old value in %edx */
                      "1:\n\t"
                      "# ending __up_write\n"
-                     : "+m" (sem->count)
-                     : "a" (sem), "i" (-RWSEM_ACTIVE_WRITE_BIAS)
-                     : "memory", "cc", "edx");
+                     : "+m" (sem->count), "=d" (tmp)
+                     : "a" (sem), "1" (-RWSEM_ACTIVE_WRITE_BIAS)
+                     : "memory", "cc");
 }
 
 /*
@@ -221,33 +230,38 @@ static inline void __up_write(struct rw_semaphore *sem)
 static inline void __downgrade_write(struct rw_semaphore *sem)
 {
         asm volatile("# beginning __downgrade_write\n\t"
-                     LOCK_PREFIX "  addl      %2,(%%eax)\n\t"
-                     /* transitions 0xZZZZ0001 -> 0xYYYY0001 */
+                     LOCK_PREFIX _ASM_ADD "%2,(%1)\n\t"
+                     /*
+                      * transitions 0xZZZZ0001 -> 0xYYYY0001 (i386)
+                      *     0xZZZZZZZZ00000001 -> 0xYYYYYYYY00000001 (x86_64)
+                      */
                      "  jns       1f\n\t"
                      "  call call_rwsem_downgrade_wake\n"
                      "1:\n\t"
                      "# ending __downgrade_write\n"
                      : "+m" (sem->count)
-                     : "a" (sem), "i" (-RWSEM_WAITING_BIAS)
+                     : "a" (sem), "er" (-RWSEM_WAITING_BIAS)
                      : "memory", "cc");
 }
 
 /*
  * implement atomic add functionality
  */
-static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
+static inline void rwsem_atomic_add(rwsem_count_t delta,
+                                    struct rw_semaphore *sem)
 {
-        asm volatile(LOCK_PREFIX "addl %1,%0"
+        asm volatile(LOCK_PREFIX _ASM_ADD "%1,%0"
                      : "+m" (sem->count)
-                     : "ir" (delta));
+                     : "er" (delta));
 }
 
 /*
  * implement exchange and add functionality
  */
-static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
+static inline rwsem_count_t rwsem_atomic_update(rwsem_count_t delta,
+                                                struct rw_semaphore *sem)
 {
-        int tmp = delta;
+        rwsem_count_t tmp = delta;
 
         asm volatile(LOCK_PREFIX "xadd %0,%1"
                      : "+r" (tmp), "+m" (sem->count)