1 files changed, 167 insertions, 0 deletions

diff --git a/include/asm-x86/spinlock_64.h b/include/asm-x86/spinlock_64.h
new file mode 100644
index 000000000000..88bf981e73cf
--- /dev/null
+++ b/include/asm-x86/spinlock_64.h
@@ -0,0 +1,167 @@
+#ifndef __ASM_SPINLOCK_H
+#define __ASM_SPINLOCK_H
+
+#include <asm/atomic.h>
+#include <asm/rwlock.h>
+#include <asm/page.h>
+#include <asm/processor.h>
+
+/*
+ * Your basic SMP spinlocks, allowing only a single CPU anywhere
+ *
+ * Simple spin lock operations.  There are two variants, one clears IRQ's
+ * on the local processor, one does not.
+ *
+ * We make no fairness assumptions. They have a cost.
+ *
+ * (the type definitions are in asm/spinlock_types.h)
+ */
+
+static inline int __raw_spin_is_locked(raw_spinlock_t *lock)
+{
+        return *(volatile signed int *)(&(lock)->slock) <= 0;
+}
+
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
+{
+        asm volatile(
+                "\n1:\t"
+                LOCK_PREFIX " ; decl %0\n\t"
+                "jns 2f\n"
+                "3:\n"
+                "rep;nop\n\t"
+                "cmpl $0,%0\n\t"
+                "jle 3b\n\t"
+                "jmp 1b\n"
+                "2:\t" : "=m" (lock->slock) : : "memory");
+}
+
+/*
+ * Same as __raw_spin_lock, but reenable interrupts during spinning.
+ */
+#ifndef CONFIG_PROVE_LOCKING
+static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
+{
+        asm volatile(
+                "\n1:\t"
+                LOCK_PREFIX " ; decl %0\n\t"
+                "jns 5f\n"
+                "testl $0x200, %1\n\t"  /* interrupts were disabled? */
+                "jz 4f\n\t"
+                "sti\n"
+                "3:\t"
+                "rep;nop\n\t"
+                "cmpl $0, %0\n\t"
+                "jle 3b\n\t"
+                "cli\n\t"
+                "jmp 1b\n"
+                "4:\t"
+                "rep;nop\n\t"
+                "cmpl $0, %0\n\t"
+                "jg 1b\n\t"
+                "jmp 4b\n"
+                "5:\n\t"
+                : "+m" (lock->slock) : "r" ((unsigned)flags) : "memory");
+}
+#endif
+
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
+{
+        int oldval;
+
+        asm volatile(
+                "xchgl %0,%1"
+                :"=q" (oldval), "=m" (lock->slock)
+                :"0" (0) : "memory");
+
+        return oldval > 0;
+}
+
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
+{
+        asm volatile("movl $1,%0" :"=m" (lock->slock) :: "memory");
+}
+
+static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock)
+{
+        while (__raw_spin_is_locked(lock))
+                cpu_relax();
+}
+
+/*
+ * Read-write spinlocks, allowing multiple readers
+ * but only one writer.
+ *
+ * NOTE! it is quite common to have readers in interrupts
+ * but no interrupt writers. For those circumstances we
+ * can "mix" irq-safe locks - any writer needs to get a
+ * irq-safe write-lock, but readers can get non-irqsafe
+ * read-locks.
+ *
+ * On x86, we implement read-write locks as a 32-bit counter
+ * with the high bit (sign) being the "contended" bit.
+ */
+
+static inline int __raw_read_can_lock(raw_rwlock_t *lock)
+{
+        return (int)(lock)->lock > 0;
+}
+
+static inline int __raw_write_can_lock(raw_rwlock_t *lock)
+{
+        return (lock)->lock == RW_LOCK_BIAS;
+}
+
+static inline void __raw_read_lock(raw_rwlock_t *rw)
+{
+        asm volatile(LOCK_PREFIX "subl $1,(%0)\n\t"
+                     "jns 1f\n"
+                     "call __read_lock_failed\n"
+                     "1:\n"
+                     ::"D" (rw), "i" (RW_LOCK_BIAS) : "memory");
+}
+
+static inline void __raw_write_lock(raw_rwlock_t *rw)
+{
+        asm volatile(LOCK_PREFIX "subl %1,(%0)\n\t"
+                     "jz 1f\n"
+                     "\tcall __write_lock_failed\n\t"
+                     "1:\n"
+                     ::"D" (rw), "i" (RW_LOCK_BIAS) : "memory");
+}
+
+static inline int __raw_read_trylock(raw_rwlock_t *lock)
+{
+        atomic_t *count = (atomic_t *)lock;
+        atomic_dec(count);
+        if (atomic_read(count) >= 0)
+                return 1;
+        atomic_inc(count);
+        return 0;
+}
+
+static inline int __raw_write_trylock(raw_rwlock_t *lock)
+{
+        atomic_t *count = (atomic_t *)lock;
+        if (atomic_sub_and_test(RW_LOCK_BIAS, count))
+                return 1;
+        atomic_add(RW_LOCK_BIAS, count);
+        return 0;
+}
+
+static inline void __raw_read_unlock(raw_rwlock_t *rw)
+{
+        asm volatile(LOCK_PREFIX " ; incl %0" :"=m" (rw->lock) : : "memory");
+}
+
+static inline void __raw_write_unlock(raw_rwlock_t *rw)
+{
+        asm volatile(LOCK_PREFIX " ; addl $" RW_LOCK_BIAS_STR ",%0"
+                                : "=m" (rw->lock) : : "memory");
+}
+
+#define _raw_spin_relax(lock)   cpu_relax()
+#define _raw_read_relax(lock)   cpu_relax()
+#define _raw_write_relax(lock)  cpu_relax()
+
+#endif /* __ASM_SPINLOCK_H */