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  1. /*
  2.  * Copyright (C) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #ifndef __ia32_ATOMIC_H__
  30. #define __ia32_ATOMIC_H__
  31.  
  32. #include <arch/types.h>
  33. #include <arch/barrier.h>
  34. #include <preemption.h>
  35. #include <typedefs.h>
  36.  
  37. static inline void atomic_inc(atomic_t *val) {
  38. #ifdef CONFIG_SMP
  39.     __asm__ volatile ("lock incl %0\n" : "=m" (val->count));
  40. #else
  41.     __asm__ volatile ("incl %0\n" : "=m" (val->count));
  42. #endif /* CONFIG_SMP */
  43. }
  44.  
  45. static inline void atomic_dec(atomic_t *val) {
  46. #ifdef CONFIG_SMP
  47.     __asm__ volatile ("lock decl %0\n" : "=m" (val->count));
  48. #else
  49.     __asm__ volatile ("decl %0\n" : "=m" (val->count));
  50. #endif /* CONFIG_SMP */
  51. }
  52.  
  53. static inline long atomic_postinc(atomic_t *val)
  54. {
  55.     long r;
  56.  
  57.     __asm__ volatile (
  58.         "movl $1, %0\n"
  59.         "lock xaddl %0, %1\n"
  60.         : "=r" (r), "=m" (val->count)
  61.     );
  62.  
  63.     return r;
  64. }
  65.  
  66. static inline long atomic_postdec(atomic_t *val)
  67. {
  68.     long r;
  69.    
  70.     __asm__ volatile (
  71.         "movl $-1, %0\n"
  72.         "lock xaddl %0, %1\n"
  73.         : "=r" (r), "=m" (val->count)
  74.     );
  75.    
  76.     return r;
  77. }
  78.  
  79. #define atomic_preinc(val) (atomic_postinc(val)+1)
  80. #define atomic_predec(val) (atomic_postdec(val)-1)
  81.  
  82. static inline __u32 test_and_set(atomic_t *val) {
  83.     __u32 v;
  84.    
  85.     __asm__ volatile (
  86.         "movl $1, %0\n"
  87.         "xchgl %0, %1\n"
  88.         : "=r" (v),"=m" (val->count)
  89.     );
  90.    
  91.     return v;
  92. }
  93.  
  94. /** ia32 specific fast spinlock */
  95. static inline void atomic_lock_arch(atomic_t *val)
  96. {
  97.     __u32 tmp;
  98.  
  99.     preemption_disable();
  100.     __asm__ volatile (
  101.         "0:;"
  102. #ifdef CONFIG_HT
  103.         "pause;" /* Pentium 4's HT love this instruction */
  104. #endif
  105.         "mov %0, %1;"
  106.         "testl %1, %1;"
  107.         "jnz 0b;"       /* Lightweight looping on locked spinlock */
  108.        
  109.         "incl %1;"      /* now use the atomic operation */
  110.         "xchgl %0, %1;"
  111.         "testl %1, %1;"
  112.         "jnz 0b;"
  113.                 : "=m"(val->count),"=r"(tmp)
  114.         );
  115.     /*
  116.      * Prevent critical section code from bleeding out this way up.
  117.      */
  118.     CS_ENTER_BARRIER();
  119. }
  120.  
  121. #endif
  122.