1 files changed, 221 insertions, 0 deletions

diff --git a/include/asm-x86/spinlock_32.h b/include/asm-x86/spinlock_32.h
new file mode 100644
index 000000000000..d3bcebed60ca
--- /dev/null
+++ b/include/asm-x86/spinlock_32.h
@@ -0,0 +1,221 @@
+#ifndef __ASM_SPINLOCK_H
+#define __ASM_SPINLOCK_H
+
+#include <asm/atomic.h>
+#include <asm/rwlock.h>
+#include <asm/page.h>
+#include <asm/processor.h>
+#include <linux/compiler.h>
+
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+#else
+#define CLI_STRING      "cli"
+#define STI_STRING      "sti"
+#define CLI_STI_CLOBBERS
+#define CLI_STI_INPUT_ARGS
+#endif /* CONFIG_PARAVIRT */
+
+/*
+ * 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 *x)
+{
+        return *(volatile signed char *)(&(x)->slock) <= 0;
+}
+
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
+{
+        asm volatile("\n1:\t"
+                     LOCK_PREFIX " ; decb %0\n\t"
+                     "jns 3f\n"
+                     "2:\t"
+                     "rep;nop\n\t"
+                     "cmpb $0,%0\n\t"
+                     "jle 2b\n\t"
+                     "jmp 1b\n"
+                     "3:\n\t"
+                     : "+m" (lock->slock) : : "memory");
+}
+
+/*
+ * It is easier for the lock validator if interrupts are not re-enabled
+ * in the middle of a lock-acquire. This is a performance feature anyway
+ * so we turn it off:
+ *
+ * NOTE: there's an irqs-on section here, which normally would have to be
+ * irq-traced, but on CONFIG_TRACE_IRQFLAGS we never use this variant.
+ */
+#ifndef CONFIG_PROVE_LOCKING
+static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
+{
+        asm volatile(
+                "\n1:\t"
+                LOCK_PREFIX " ; decb %[slock]\n\t"
+                "jns 5f\n"
+                "2:\t"
+                "testl $0x200, %[flags]\n\t"
+                "jz 4f\n\t"
+                STI_STRING "\n"
+                "3:\t"
+                "rep;nop\n\t"
+                "cmpb $0, %[slock]\n\t"
+                "jle 3b\n\t"
+                CLI_STRING "\n\t"
+                "jmp 1b\n"
+                "4:\t"
+                "rep;nop\n\t"
+                "cmpb $0, %[slock]\n\t"
+                "jg 1b\n\t"
+                "jmp 4b\n"
+                "5:\n\t"
+                : [slock] "+m" (lock->slock)
+                : [flags] "r" (flags)
+                  CLI_STI_INPUT_ARGS
+                : "memory" CLI_STI_CLOBBERS);
+}
+#endif
+
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
+{
+        char oldval;
+        asm volatile(
+                "xchgb %b0,%1"
+                :"=q" (oldval), "+m" (lock->slock)
+                :"0" (0) : "memory");
+        return oldval > 0;
+}
+
+/*
+ * __raw_spin_unlock based on writing $1 to the low byte.
+ * This method works. Despite all the confusion.
+ * (except on PPro SMP or if we are using OOSTORE, so we use xchgb there)
+ * (PPro errata 66, 92)
+ */
+
+#if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE)
+
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
+{
+        asm volatile("movb $1,%0" : "+m" (lock->slock) :: "memory");
+}
+
+#else
+
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
+{
+        char oldval = 1;
+
+        asm volatile("xchgb %b0, %1"
+                     : "=q" (oldval), "+m" (lock->slock)
+                     : "0" (oldval) : "memory");
+}
+
+#endif
+
+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.
+ *
+ * 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 helpers are in arch/i386/kernel/semaphore.c
+ */
+
+/**
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+static inline int __raw_read_can_lock(raw_rwlock_t *x)
+{
+        return (int)(x)->lock > 0;
+}
+
+/**
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+static inline int __raw_write_can_lock(raw_rwlock_t *x)
+{
+        return (x)->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\t"
+                     "1:\n"
+                     ::"a" (rw) : "memory");
+}
+
+static inline void __raw_write_lock(raw_rwlock_t *rw)
+{
+        asm volatile(LOCK_PREFIX " subl $" RW_LOCK_BIAS_STR ",(%0)\n\t"
+                     "jz 1f\n"
+                     "call __write_lock_failed\n\t"
+                     "1:\n"
+                     ::"a" (rw) : "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 */