Add ACCESS_ONCE to _STORE_SHARED

[urcu.git] / arch_x86.h

/*
 * arch_x86.h: Definitions for the x86 architecture, derived from Linux.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; but only version 2 of the License given
 * that this comes from the Linux kernel.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
 */

/* Assume P4 or newer */
#define CONFIG_HAVE_FENCE 1
#define CONFIG_HAVE_MEM_COHERENCY

#ifdef CONFIG_HAVE_FENCE
#define mb()    asm volatile("mfence":::"memory")
#define rmb()   asm volatile("lfence":::"memory")
#define wmb()   asm volatile("sfence"::: "memory")
#else
/*
 * Some non-Intel clones support out of order store. wmb() ceases to be a
 * nop for these.
 */
#define mb()    asm volatile("lock; addl $0,0(%%esp)":::"memory")
#define rmb()   asm volatile("lock; addl $0,0(%%esp)":::"memory")
#define wmb()   asm volatile("lock; addl $0,0(%%esp)"::: "memory")
#endif

/*
 * Architectures without cache coherency need something like the following:
 *
 * #define mb()		mc()
 * #define rmb()	rmc()
 * #define wmb()	wmc()
 * #define mc()		arch_cache_flush()
 * #define rmc()	arch_cache_flush_read()
 * #define wmc()	arch_cache_flush_write()
 */

#define mc()	barrier()
#define rmc()	barrier()
#define wmc()	barrier()

/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
static inline void rep_nop(void)
{
	asm volatile("rep; nop" ::: "memory");
}

static inline void cpu_relax(void)
{
	rep_nop();
}

#ifndef _INCLUDE_API_H

static inline void atomic_inc(int *v)
{
	asm volatile("lock; incl %0"
		     : "+m" (*v));
}

#endif /* #ifndef _INCLUDE_API_H */

#define xchg(ptr, v)							\
	((__typeof__(*(ptr)))__xchg((unsigned long)(v), (ptr), sizeof(*(ptr))))

struct __xchg_dummy {
	unsigned long a[100];
};
#define __xg(x) ((struct __xchg_dummy *)(x))

/*
 * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
 * Note 2: xchg has side effect, so that attribute volatile is necessary,
 *	  but generally the primitive is invalid, *ptr is output argument. --ANK
 * x is considered local, ptr is considered remote.
 */
static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
				   int size)
{
	switch (size) {
	case 1:
		asm volatile("xchgb %b0,%1"
			     : "=q" (x)
			     : "m" (*__xg(ptr)), "0" (x)
			     : "memory");
		break;
	case 2:
		asm volatile("xchgw %w0,%1"
			     : "=r" (x)
			     : "m" (*__xg(ptr)), "0" (x)
			     : "memory");
		break;
	case 4:
		asm volatile("xchgl %k0,%1"
			     : "=r" (x)
			     : "m" (*__xg(ptr)), "0" (x)
			     : "memory");
		break;
	case 8:
		asm volatile("xchgq %0,%1"
			     : "=r" (x)
			     : "m" (*__xg(ptr)), "0" (x)
			     : "memory");
		break;
	}
	smp_wmc();
	return x;
}


#define rdtscll(val) do { \
     unsigned int __a,__d; \
     asm volatile("rdtsc" : "=a" (__a), "=d" (__d)); \
     (val) = ((unsigned long long)__a) | (((unsigned long long)__d)<<32); \
} while(0)

typedef unsigned long long cycles_t;

static inline cycles_t get_cycles (void)
{
        unsigned long long ret = 0;

        rdtscll(ret);
        return ret;
}