[libcpu/aarch64]修改atomic实现

libcpu/aarch64/common/atomic_aarch64.c

@@ -90,7 +90,6 @@ rt_atomic_t rt_hw_atomic_flag_test_and_set(volatile rt_atomic_t *ptr)
 rt_atomic_t rt_hw_atomic_compare_exchange_strong(volatile rt_atomic_t *ptr, rt_atomic_t *old, rt_atomic_t new)
 {
     rt_atomic_t tmp, oldval;
-
     __asm__ volatile (
         "   prfm    pstl1strm, %2\n"
         "1: ldxr    %0, %2\n"
@@ -99,10 +98,15 @@ rt_atomic_t rt_hw_atomic_compare_exchange_strong(volatile rt_atomic_t *ptr, rt_a
         "   stlxr   %w1, %4, %2\n"
         "   cbnz    %w1, 1b\n"
         "   dmb     ish\n"
-        "2:"
+        "   mov     %w1, #1\n"
+        "   b       3f\n"
+        "2: str     %0, [%5]\n"
+        "   mov     %w1, #0\n"
+        "3:"
         : "=&r" (oldval), "=&r" (tmp), "+Q" (*ptr)
-        : "Kr" (*old), "r" (new)
+        : "Kr" (*old), "r" (new), "r" (old)
         : "memory");
 
-    return oldval == *old;
+    return tmp;
 }
+