include/asm-i386/spinlock.h

   1 #ifndef __ASM_SPINLOCK_H
   2 #define __ASM_SPINLOCK_H
   3
   4 #include <asm/atomic.h>
   5 #include <asm/rwlock.h>
   6 #include <asm/page.h>
   7 #include <linux/config.h>
   8 #include <linux/compiler.h>
   9
  10 asmlinkage int printk(const char * fmt, ...)
  11         __attribute__ ((format (printf, 1, 2)));
  12
  13 /*
  14  * Your basic SMP spinlocks, allowing only a single CPU anywhere
  15  */
  16
  17 typedef struct {
  18         volatile unsigned int lock;
  19 #ifdef CONFIG_DEBUG_SPINLOCK
  20         unsigned magic;
  21 #endif
  22 } spinlock_t;
  23
  24 #define SPINLOCK_MAGIC  0xdead4ead
  25
  26 #ifdef CONFIG_DEBUG_SPINLOCK
  27 #define SPINLOCK_MAGIC_INIT     , SPINLOCK_MAGIC
  28 #else
  29 #define SPINLOCK_MAGIC_INIT     /* */
  30 #endif
  31
  32 #define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 SPINLOCK_MAGIC_INIT }
  33
  34 #define spin_lock_init(x)       do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
  35
  36 /*
  37  * Simple spin lock operations.  There are two variants, one clears IRQ's
  38  * on the local processor, one does not.
  39  *
  40  * We make no fairness assumptions. They have a cost.
  41  */
  42
  43 #define spin_is_locked(x)       (*(volatile signed char *)(&(x)->lock) <= 0)
  44 #define spin_unlock_wait(x)     do { barrier(); } while(spin_is_locked(x))
  45
  46 #define spin_lock_string \
  47         "\n1:\t" \
  48         "lock ; decb %0\n\t" \
  49         "js 2f\n" \
  50         LOCK_SECTION_START("") \
  51         "2:\t" \
  52         "rep;nop\n\t" \
  53         "cmpb $0,%0\n\t" \
  54         "jle 2b\n\t" \
  55         "jmp 1b\n" \
  56         LOCK_SECTION_END
  57
  58 #define spin_lock_string_flags \
  59         "\n1:\t" \
  60         "lock ; decb %0\n\t" \
  61         "js 2f\n\t" \
  62         LOCK_SECTION_START("") \
  63         "2:\t" \
  64         "testl $0x200, %1\n\t" \
  65         "jz 3f\n\t" \
  66         "sti\n\t" \
  67         "3:\t" \
  68         "rep;nop\n\t" \
  69         "cmpb $0, %0\n\t" \
  70         "jle 3b\n\t" \
  71         "cli\n\t" \
  72         "jmp 1b\n" \
  73         LOCK_SECTION_END
  74
  75 /*
  76  * This works. Despite all the confusion.
  77  * (except on PPro SMP or if we are using OOSTORE)
  78  * (PPro errata 66, 92)
  79  */
  80
  81 #if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE)
  82
  83 #define spin_unlock_string \
  84         "movb $1,%0" \
  85                 :"=m" (lock->lock) : : "memory"
  86
  87
  88 static inline void _raw_spin_unlock(spinlock_t *lock)
  89 {
  90 #ifdef CONFIG_DEBUG_SPINLOCK
  91         BUG_ON(lock->magic != SPINLOCK_MAGIC);
  92         BUG_ON(!spin_is_locked(lock));
  93 #endif
  94         __asm__ __volatile__(
  95                 spin_unlock_string
  96         );
  97 }
  98
  99 #else
 100
 101 #define spin_unlock_string \
 102         "xchgb %b0, %1" \
 103                 :"=q" (oldval), "=m" (lock->lock) \
 104                 :"0" (oldval) : "memory"
 105
 106 static inline void _raw_spin_unlock(spinlock_t *lock)
 107 {
 108         char oldval = 1;
 109 #ifdef CONFIG_DEBUG_SPINLOCK
 110         BUG_ON(lock->magic != SPINLOCK_MAGIC);
 111         BUG_ON(!spin_is_locked(lock));
 112 #endif
 113         __asm__ __volatile__(
 114                 spin_unlock_string
 115         );
 116 }
 117
 118 #endif
 119
 120 static inline int _raw_spin_trylock(spinlock_t *lock)
 121 {
 122         char oldval;
 123         __asm__ __volatile__(
 124                 "xchgb %b0,%1"
 125                 :"=q" (oldval), "=m" (lock->lock)
 126                 :"0" (0) : "memory");
 127         return oldval > 0;
 128 }
 129
 130 static inline void _raw_spin_lock(spinlock_t *lock)
 131 {
 132 #ifdef CONFIG_DEBUG_SPINLOCK
 133         __label__ here;
 134 here:
 135         if (unlikely(lock->magic != SPINLOCK_MAGIC)) {
 136                 printk("eip: %p\n", &&here);
 137                 BUG();
 138         }
 139 #endif
 140         __asm__ __volatile__(
 141                 spin_lock_string
 142                 :"=m" (lock->lock) : : "memory");
 143 }
 144
 145 static inline void _raw_spin_lock_flags (spinlock_t *lock, unsigned long flags)
 146 {
 147 #ifdef CONFIG_DEBUG_SPINLOCK
 148         __label__ here;
 149 here:
 150         if (unlikely(lock->magic != SPINLOCK_MAGIC)) {
 151                 printk("eip: %p\n", &&here);
 152                 BUG();
 153         }
 154 #endif
 155         __asm__ __volatile__(
 156                 spin_lock_string_flags
 157                 :"=m" (lock->lock) : "r" (flags) : "memory");
 158 }
 159
 160 /*
 161  * Read-write spinlocks, allowing multiple readers
 162  * but only one writer.
 163  *
 164  * NOTE! it is quite common to have readers in interrupts
 165  * but no interrupt writers. For those circumstances we
 166  * can "mix" irq-safe locks - any writer needs to get a
 167  * irq-safe write-lock, but readers can get non-irqsafe
 168  * read-locks.
 169  */
 170 typedef struct {
 171         volatile unsigned int lock;
 172 #ifdef CONFIG_DEBUG_SPINLOCK
 173         unsigned magic;
 174 #endif
 175 } rwlock_t;
 176
 177 #define RWLOCK_MAGIC    0xdeaf1eed
 178
 179 #ifdef CONFIG_DEBUG_SPINLOCK
 180 #define RWLOCK_MAGIC_INIT       , RWLOCK_MAGIC
 181 #else
 182 #define RWLOCK_MAGIC_INIT       /* */
 183 #endif
 184
 185 #define RW_LOCK_UNLOCKED (rwlock_t) { RW_LOCK_BIAS RWLOCK_MAGIC_INIT }
 186
 187 #define rwlock_init(x)  do { *(x) = RW_LOCK_UNLOCKED; } while(0)
 188
 189 #define rwlock_is_locked(x) ((x)->lock != RW_LOCK_BIAS)
 190
 191 /*
 192  * On x86, we implement read-write locks as a 32-bit counter
 193  * with the high bit (sign) being the "contended" bit.
 194  *
 195  * The inline assembly is non-obvious. Think about it.
 196  *
 197  * Changed to use the same technique as rw semaphores.  See
 198  * semaphore.h for details.  -ben
 199  */
 200 /* the spinlock helpers are in arch/i386/kernel/semaphore.c */
 201
 202 static inline void _raw_read_lock(rwlock_t *rw)
 203 {
 204 #ifdef CONFIG_DEBUG_SPINLOCK
 205         BUG_ON(rw->magic != RWLOCK_MAGIC);
 206 #endif
 207         __build_read_lock(rw, "__read_lock_failed");
 208 }
 209
 210 static inline void _raw_write_lock(rwlock_t *rw)
 211 {
 212 #ifdef CONFIG_DEBUG_SPINLOCK
 213         BUG_ON(rw->magic != RWLOCK_MAGIC);
 214 #endif
 215         __build_write_lock(rw, "__write_lock_failed");
 216 }
 217
 218 #define _raw_read_unlock(rw)            asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
 219 #define _raw_write_unlock(rw)   asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
 220
 221 static inline int _raw_write_trylock(rwlock_t *lock)
 222 {
 223         atomic_t *count = (atomic_t *)lock;
 224         if (atomic_sub_and_test(RW_LOCK_BIAS, count))
 225                 return 1;
 226         atomic_add(RW_LOCK_BIAS, count);
 227         return 0;
 228 }
 229
 230 #endif /* __ASM_SPINLOCK_H */