ltt-usertrace/ltt/kernelutils-i386.h

   1 /*****************************************************************************
   2  * kernelutils-x386.h
   3  *
   4  * This file holds the code needed by LTT usertrace that comes from the
   5  * kernel headers.  Since including kernel headers is not recommended in
   6  * userspace programs/libraries, we rewrote implementations HIGHLY INSPIRED
   7  * (i.e. copied/pasted) from the original kernel headers (2.6.17).
   8  *
   9  * Martin Bisson, July 2006
  10  * Mathieu Desnoyers, August 2006
  11  */
  12
  13 #ifndef _KERNELUTILS_I386_H
  14 #define _KERNELUTILS_I386_H
  15
  16 // We are careful, so we assume a possibly SMP machine
  17 #define LOCK "lock ; "
  18 #define LOCK_PREFIX "lock ; "
  19
  20
  21
  22
  23 // From atomic.h
  24
  25
  26 /*
  27  * Make sure gcc doesn't try to be clever and move things around
  28  * on us. We need to use _exactly_ the address the user gave us,
  29  * not some alias that contains the same information.
  30  */
  31 typedef struct { volatile int counter; } atomic_t;
  32
  33
  34 /**
  35  * atomic_read - read atomic variable
  36  * @v: pointer of type atomic_t
  37  *
  38  * Atomically reads the value of @v.
  39  */
  40 #define atomic_read(v)          ((v)->counter)
  41
  42 /**
  43  * atomic_add - add integer to atomic variable
  44  * @i: integer value to add
  45  * @v: pointer of type atomic_t
  46  *
  47  * Atomically adds @i to @v.
  48  */
  49 static __inline__ void atomic_add(int i, atomic_t *v)
  50 {
  51         __asm__ __volatile__(
  52                 LOCK "addl %1,%0"
  53                 :"=m" (v->counter)
  54                 :"ir" (i), "m" (v->counter));
  55 }
  56
  57 /**
  58  * atomic_inc - increment atomic variable
  59  * @v: pointer of type atomic_t
  60  *
  61  * Atomically increments @v by 1.
  62  */
  63 static __inline__ void atomic_inc(atomic_t *v)
  64 {
  65         __asm__ __volatile__(
  66                 LOCK "incl %0"
  67                 :"=m" (v->counter)
  68                 :"m" (v->counter));
  69 }
  70
  71 /**
  72  * atomic_add_return - add and return
  73  * @i: integer value to add
  74  * @v: pointer of type atomic_t
  75  *
  76  * Atomically adds @i to @v and returns @i + @v
  77  */
  78 static __inline__ int atomic_add_return(int i, atomic_t *v)
  79 {
  80         int __i = i;
  81         __asm__ __volatile__(
  82                 LOCK "xaddl %0, %1;"
  83                 :"=r"(i)
  84                 :"m"(v->counter), "0"(i));
  85         return i + __i;
  86 }
  87
  88
  89
  90
  91 // From system.h
  92
  93 struct __xchg_dummy { unsigned long a[100]; };
  94 #define __xg(x) ((struct __xchg_dummy *)(x))
  95
  96
  97 /*
  98  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
  99  * store NEW in MEM.  Return the initial value in MEM.  Success is
 100  * indicated by comparing RETURN with OLD.
 101  */
 102
 103 #define __HAVE_ARCH_CMPXCHG 1
 104 #define cmpxchg(ptr,o,n)\
 105         ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
 106                                         (unsigned long)(n),sizeof(*(ptr))))
 107
 108 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 109                                       unsigned long new, int size)
 110 {
 111         unsigned long prev;
 112         switch (size) {
 113         case 1:
 114                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgb %b1,%2"
 115                                      : "=a"(prev)
 116                                      : "q"(new), "m"(*__xg(ptr)), "0"(old)
 117                                      : "memory");
 118                 return prev;
 119         case 2:
 120                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
 121                                      : "=a"(prev)
 122                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
 123                                      : "memory");
 124                 return prev;
 125         case 4:
 126                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2"
 127                                      : "=a"(prev)
 128                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
 129                                      : "memory");
 130                 return prev;
 131         }
 132         return old;
 133 }
 134
 135
 136 // From msr.h
 137
 138 #define rdtscll(val) \
 139      __asm__ __volatile__("rdtsc" : "=A" (val))
 140
 141 // From timex.h
 142
 143 typedef unsigned long long cycles_t;
 144
 145 static inline cycles_t get_cycles (void)
 146 {
 147         unsigned long long ret;
 148
 149         rdtscll(ret);
 150         return ret;
 151 }
 152
 153
 154 #endif // _KERNELUTILS_I386_H