1 files changed, 214 insertions, 0 deletions

diff --git a/include/asm-x86_64/spinlock.h b/include/asm-x86_64/spinlock.h
new file mode 100644
index 000000000000..5aeb57a3baad
--- /dev/null
+++ b/include/asm-x86_64/spinlock.h
@@ -0,0 +1,214 @@
+#ifndef __ASM_SPINLOCK_H
+#define __ASM_SPINLOCK_H
+
+#include <asm/atomic.h>
+#include <asm/rwlock.h>
+#include <asm/page.h>
+#include <linux/config.h>
+
+extern int printk(const char * fmt, ...)
+        __attribute__ ((format (printf, 1, 2)));
+
+/*
+ * Your basic SMP spinlocks, allowing only a single CPU anywhere
+ */
+
+typedef struct {
+        volatile unsigned int lock;
+#ifdef CONFIG_DEBUG_SPINLOCK
+        unsigned magic;
+#endif
+#ifdef CONFIG_PREEMPT
+        unsigned int break_lock;
+#endif
+} spinlock_t;
+
+#define SPINLOCK_MAGIC  0xdead4ead
+
+#ifdef CONFIG_DEBUG_SPINLOCK
+#define SPINLOCK_MAGIC_INIT     , SPINLOCK_MAGIC
+#else
+#define SPINLOCK_MAGIC_INIT     /* */
+#endif
+
+#define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 SPINLOCK_MAGIC_INIT }
+
+#define spin_lock_init(x)       do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
+
+/*
+ * 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.
+ */
+
+#define spin_is_locked(x)       (*(volatile signed char *)(&(x)->lock) <= 0)
+#define spin_unlock_wait(x)     do { barrier(); } while(spin_is_locked(x))
+#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
+
+#define spin_lock_string \
+        "\n1:\t" \
+        "lock ; decb %0\n\t" \
+        "js 2f\n" \
+        LOCK_SECTION_START("") \
+        "2:\t" \
+        "rep;nop\n\t" \
+        "cmpb $0,%0\n\t" \
+        "jle 2b\n\t" \
+        "jmp 1b\n" \
+        LOCK_SECTION_END
+
+/*
+ * This works. Despite all the confusion.
+ * (except on PPro SMP or if we are using OOSTORE)
+ * (PPro errata 66, 92)
+ */
+ 
+#if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE)
+
+#define spin_unlock_string \
+        "movb $1,%0" \
+                :"=m" (lock->lock) : : "memory"
+
+
+static inline void _raw_spin_unlock(spinlock_t *lock)
+{
+#ifdef CONFIG_DEBUG_SPINLOCK
+        BUG_ON(lock->magic != SPINLOCK_MAGIC);
+        assert_spin_locked(lock);
+#endif
+        __asm__ __volatile__(
+                spin_unlock_string
+        );
+}
+
+#else
+
+#define spin_unlock_string \
+        "xchgb %b0, %1" \
+                :"=q" (oldval), "=m" (lock->lock) \
+                :"0" (oldval) : "memory"
+
+static inline void _raw_spin_unlock(spinlock_t *lock)
+{
+        char oldval = 1;
+#ifdef CONFIG_DEBUG_SPINLOCK
+        BUG_ON(lock->magic != SPINLOCK_MAGIC);
+        assert_spin_locked(lock);
+#endif
+        __asm__ __volatile__(
+                spin_unlock_string
+        );
+}
+
+#endif
+
+static inline int _raw_spin_trylock(spinlock_t *lock)
+{
+        char oldval;
+        __asm__ __volatile__(
+                "xchgb %b0,%1"
+                :"=q" (oldval), "=m" (lock->lock)
+                :"0" (0) : "memory");
+        return oldval > 0;
+}
+
+static inline void _raw_spin_lock(spinlock_t *lock)
+{
+#ifdef CONFIG_DEBUG_SPINLOCK
+        if (lock->magic != SPINLOCK_MAGIC) {
+                printk("eip: %p\n", __builtin_return_address(0));
+                BUG();
+        }
+#endif
+        __asm__ __volatile__(
+                spin_lock_string
+                :"=m" (lock->lock) : : "memory");
+}
+
+
+/*
+ * 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.
+ */
+typedef struct {
+        volatile unsigned int lock;
+#ifdef CONFIG_DEBUG_SPINLOCK
+        unsigned magic;
+#endif
+#ifdef CONFIG_PREEMPT
+        unsigned int break_lock;
+#endif
+} rwlock_t;
+
+#define RWLOCK_MAGIC    0xdeaf1eed
+
+#ifdef CONFIG_DEBUG_SPINLOCK
+#define RWLOCK_MAGIC_INIT       , RWLOCK_MAGIC
+#else
+#define RWLOCK_MAGIC_INIT       /* */
+#endif
+
+#define RW_LOCK_UNLOCKED (rwlock_t) { RW_LOCK_BIAS RWLOCK_MAGIC_INIT }
+
+#define rwlock_init(x)  do { *(x) = RW_LOCK_UNLOCKED; } while(0)
+
+#define read_can_lock(x)        ((int)(x)->lock > 0)
+#define write_can_lock(x)       ((x)->lock == RW_LOCK_BIAS)
+
+/*
+ * On x86, we implement read-write locks as a 32-bit counter
+ * with the high bit (sign) being the "contended" bit.
+ *
+ * The inline assembly is non-obvious. Think about it.
+ *
+ * Changed to use the same technique as rw semaphores.  See
+ * semaphore.h for details.  -ben
+ */
+/* the spinlock helpers are in arch/i386/kernel/semaphore.c */
+
+static inline void _raw_read_lock(rwlock_t *rw)
+{
+#ifdef CONFIG_DEBUG_SPINLOCK
+        BUG_ON(rw->magic != RWLOCK_MAGIC);
+#endif
+        __build_read_lock(rw, "__read_lock_failed");
+}
+
+static inline void _raw_write_lock(rwlock_t *rw)
+{
+#ifdef CONFIG_DEBUG_SPINLOCK
+        BUG_ON(rw->magic != RWLOCK_MAGIC);
+#endif
+        __build_write_lock(rw, "__write_lock_failed");
+}
+
+#define _raw_read_unlock(rw)            asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
+#define _raw_write_unlock(rw)   asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
+
+static inline int _raw_read_trylock(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(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;
+}
+
+#endif /* __ASM_SPINLOCK_H */