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Diffstat (limited to 'arch/arm64/include/asm/spinlock.h')
-rw-r--r--arch/arm64/include/asm/spinlock.h23
1 files changed, 21 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index c85e96d174a5..fc9682bfe002 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -26,9 +26,28 @@
* The memory barriers are implicit with the load-acquire and store-release
* instructions.
*/
+static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
+{
+ unsigned int tmp;
+ arch_spinlock_t lockval;
-#define arch_spin_unlock_wait(lock) \
- do { while (arch_spin_is_locked(lock)) cpu_relax(); } while (0)
+ asm volatile(
+" sevl\n"
+"1: wfe\n"
+"2: ldaxr %w0, %2\n"
+" eor %w1, %w0, %w0, ror #16\n"
+" cbnz %w1, 1b\n"
+ 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")
+ : "=&r" (lockval), "=&r" (tmp), "+Q" (*lock)
+ :
+ : "memory");
+}
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)