"2: ldaxr %w0, %2\n"
" eor %w1, %w0, %w0, ror #16\n"
" cbnz %w1, 1b\n"
+ /* Serialise against any concurrent lockers */
ARM64_LSE_ATOMIC_INSN(
/* LL/SC */
" stxr %w1, %w0, %2\n"
-" cbnz %w1, 2b\n", /* Serialise against any concurrent lockers */
- /* LSE atomics */
" nop\n"
-" nop\n")
+" nop\n",
+ /* LSE atomics */
+" mov %w1, %w0\n"
+" cas %w0, %w0, %2\n"
+" eor %w1, %w1, %w0\n")
+" cbnz %w1, 2b\n"
: "=&r" (lockval), "=&r" (tmp), "+Q" (*lock)
:
: "memory");
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
+/*
+ * Accesses appearing in program order before a spin_lock() operation
+ * can be reordered with accesses inside the critical section, by virtue
+ * of arch_spin_lock being constructed using acquire semantics.
+ *
+ * In cases where this is problematic (e.g. try_to_wake_up), an
+ * smp_mb__before_spinlock() can restore the required ordering.
+ */
+#define smp_mb__before_spinlock() smp_mb()
+
#endif /* __ASM_SPINLOCK_H */