X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=include%2Fasm-x86%2Fspinlock.h;h=21e89bf92f1c8cd547b697fcc37021388d8115e2;hb=1beee8dc8cf58e3f605bd7b34d7a39939be7d8d2;hp=d74d85e71dcb071b2be8688a726f3a36f2a68b9f;hpb=e86908614f2c7fec401827e5cefd7a6ea9407f85;p=linux-2.6

diff --git a/include/asm-x86/spinlock.h b/include/asm-x86/spinlock.h
index d74d85e71d..21e89bf92f 100644
--- a/include/asm-x86/spinlock.h
+++ b/include/asm-x86/spinlock.h
@@ -1,5 +1,281 @@
+#ifndef _X86_SPINLOCK_H_
+#define _X86_SPINLOCK_H_
+
+#include <asm/atomic.h>
+#include <asm/rwlock.h>
+#include <asm/page.h>
+#include <asm/processor.h>
+#include <linux/compiler.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.
+ *
+ * These are fair FIFO ticket locks, which are currently limited to 256
+ * CPUs.
+ *
+ * (the type definitions are in asm/spinlock_types.h)
+ */
+
 #ifdef CONFIG_X86_32
-# include "spinlock_32.h"
+# define LOCK_PTR_REG "a"
 #else
-# include "spinlock_64.h"
+# define LOCK_PTR_REG "D"
+#endif
+
+#if defined(CONFIG_X86_32) && \
+	(defined(CONFIG_X86_OOSTORE) || defined(CONFIG_X86_PPRO_FENCE))
+/*
+ * On PPro SMP or if we are using OOSTORE, we use a locked operation to unlock
+ * (PPro errata 66, 92)
+ */
+# define UNLOCK_LOCK_PREFIX LOCK_PREFIX
+#else
+# define UNLOCK_LOCK_PREFIX
+#endif
+
+/*
+ * Ticket locks are conceptually two parts, one indicating the current head of
+ * the queue, and the other indicating the current tail. The lock is acquired
+ * by atomically noting the tail and incrementing it by one (thus adding
+ * ourself to the queue and noting our position), then waiting until the head
+ * becomes equal to the the initial value of the tail.
+ *
+ * We use an xadd covering *both* parts of the lock, to increment the tail and
+ * also load the position of the head, which takes care of memory ordering
+ * issues and should be optimal for the uncontended case. Note the tail must be
+ * in the high part, because a wide xadd increment of the low part would carry
+ * up and contaminate the high part.
+ *
+ * With fewer than 2^8 possible CPUs, we can use x86's partial registers to
+ * save some instructions and make the code more elegant. There really isn't
+ * much between them in performance though, especially as locks are out of line.
+ */
+#if (NR_CPUS < 256)
+static inline int __raw_spin_is_locked(raw_spinlock_t *lock)
+{
+	int tmp = ACCESS_ONCE(lock->slock);
+
+	return (((tmp >> 8) & 0xff) != (tmp & 0xff));
+}
+
+static inline int __raw_spin_is_contended(raw_spinlock_t *lock)
+{
+	int tmp = ACCESS_ONCE(lock->slock);
+
+	return (((tmp >> 8) & 0xff) - (tmp & 0xff)) > 1;
+}
+
+static __always_inline void __raw_spin_lock(raw_spinlock_t *lock)
+{
+	short inc = 0x0100;
+
+	asm volatile (
+		LOCK_PREFIX "xaddw %w0, %1\n"
+		"1:\t"
+		"cmpb %h0, %b0\n\t"
+		"je 2f\n\t"
+		"rep ; nop\n\t"
+		"movb %1, %b0\n\t"
+		/* don't need lfence here, because loads are in-order */
+		"jmp 1b\n"
+		"2:"
+		: "+Q" (inc), "+m" (lock->slock)
+		:
+		: "memory", "cc");
+}
+
+#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
+
+static __always_inline int __raw_spin_trylock(raw_spinlock_t *lock)
+{
+	int tmp;
+	short new;
+
+	asm volatile("movw %2,%w0\n\t"
+		     "cmpb %h0,%b0\n\t"
+		     "jne 1f\n\t"
+		     "movw %w0,%w1\n\t"
+		     "incb %h1\n\t"
+		     "lock ; cmpxchgw %w1,%2\n\t"
+		     "1:"
+		     "sete %b1\n\t"
+		     "movzbl %b1,%0\n\t"
+		     : "=&a" (tmp), "=Q" (new), "+m" (lock->slock)
+		     :
+		     : "memory", "cc");
+
+	return tmp;
+}
+
+static __always_inline void __raw_spin_unlock(raw_spinlock_t *lock)
+{
+	asm volatile(UNLOCK_LOCK_PREFIX "incb %0"
+		     : "+m" (lock->slock)
+		     :
+		     : "memory", "cc");
+}
+#else
+static inline int __raw_spin_is_locked(raw_spinlock_t *lock)
+{
+	int tmp = ACCESS_ONCE(lock->slock);
+
+	return (((tmp >> 16) & 0xffff) != (tmp & 0xffff));
+}
+
+static inline int __raw_spin_is_contended(raw_spinlock_t *lock)
+{
+	int tmp = ACCESS_ONCE(lock->slock);
+
+	return (((tmp >> 16) & 0xffff) - (tmp & 0xffff)) > 1;
+}
+
+static __always_inline void __raw_spin_lock(raw_spinlock_t *lock)
+{
+	int inc = 0x00010000;
+	int tmp;
+
+	asm volatile("lock ; xaddl %0, %1\n"
+		     "movzwl %w0, %2\n\t"
+		     "shrl $16, %0\n\t"
+		     "1:\t"
+		     "cmpl %0, %2\n\t"
+		     "je 2f\n\t"
+		     "rep ; nop\n\t"
+		     "movzwl %1, %2\n\t"
+		     /* don't need lfence here, because loads are in-order */
+		     "jmp 1b\n"
+		     "2:"
+		     : "+Q" (inc), "+m" (lock->slock), "=r" (tmp)
+		     :
+		     : "memory", "cc");
+}
+
+#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
+
+static __always_inline int __raw_spin_trylock(raw_spinlock_t *lock)
+{
+	int tmp;
+	int new;
+
+	asm volatile("movl %2,%0\n\t"
+		     "movl %0,%1\n\t"
+		     "roll $16, %0\n\t"
+		     "cmpl %0,%1\n\t"
+		     "jne 1f\n\t"
+		     "addl $0x00010000, %1\n\t"
+		     "lock ; cmpxchgl %1,%2\n\t"
+		     "1:"
+		     "sete %b1\n\t"
+		     "movzbl %b1,%0\n\t"
+		     : "=&a" (tmp), "=r" (new), "+m" (lock->slock)
+		     :
+		     : "memory", "cc");
+
+	return tmp;
+}
+
+static __always_inline void __raw_spin_unlock(raw_spinlock_t *lock)
+{
+	asm volatile(UNLOCK_LOCK_PREFIX "incw %0"
+		     : "+m" (lock->slock)
+		     :
+		     : "memory", "cc");
+}
+#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.
+ */
+
+/**
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+static inline int __raw_read_can_lock(raw_rwlock_t *lock)
+{
+	return (int)(lock)->lock > 0;
+}
+
+/**
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+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\t"
+		     "1:\n"
+		     ::LOCK_PTR_REG (rw) : "memory");
+}
+
+static inline void __raw_write_lock(raw_rwlock_t *rw)
+{
+	asm volatile(LOCK_PREFIX " subl %1,(%0)\n\t"
+		     "jz 1f\n"
+		     "call __write_lock_failed\n\t"
+		     "1:\n"
+		     ::LOCK_PTR_REG (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 %1, %0"
+		     : "+m" (rw->lock) : "i" (RW_LOCK_BIAS) : "memory");
+}
+
+#define _raw_spin_relax(lock)	cpu_relax()
+#define _raw_read_relax(lock)	cpu_relax()
+#define _raw_write_relax(lock)	cpu_relax()
+
 #endif