system.h

xen 3.2.2 源码

/*
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright (C) IBM Corp. 2005
 *
 * Authors: Jimi Xenidis <[e-mail]>
 */

#ifndef _ASM_SYSTEM_H_
#define _ASM_SYSTEM_H_

#include <xen/config.h>
#include <xen/lib.h>
#include <asm/memory.h>
#include <asm/time.h>
#include <asm/processor.h>
#include <asm/msr.h>

#define xchg(ptr,x) 							       \
({									       \
	__typeof__(*(ptr)) _x_ = (x);					       \
	(__typeof__(*(ptr))) __xchg((ptr), (unsigned long)_x_, sizeof(*(ptr))); \
})

static __inline__ unsigned long
__xchg_u32(volatile int *m, unsigned long val)
{
    unsigned long dummy;

    __asm__ __volatile__(
    EIEIO_ON_SMP
"1: lwarx %0,0,%3       # __xchg_u32\n\
    stwcx. %2,0,%3\n\
2:  bne- 1b"
    ISYNC_ON_SMP
    : "=&r" (dummy), "=m" (*m)
    : "r" (val), "r" (m)
    : "cc", "memory");

    return (dummy);
}

static __inline__ unsigned long
__xchg_u64(volatile long *m, unsigned long val)
{
    unsigned long dummy;

    __asm__ __volatile__(
    EIEIO_ON_SMP
"1: ldarx %0,0,%3       # __xchg_u64\n\
    stdcx. %2,0,%3\n\
2:  bne- 1b"
    ISYNC_ON_SMP
    : "=&r" (dummy), "=m" (*m)
    : "r" (val), "r" (m)
    : "cc", "memory");

    return (dummy);
}

/*
 * This function doesn't exist, so you'll get a linker error
 * if something tries to do an invalid xchg().
 */
extern void __xchg_called_with_bad_pointer(void);

static __inline__ unsigned long
__xchg(volatile void *ptr, unsigned long x, int size)
{
    switch (size) {
    case 4:
        return __xchg_u32(ptr, x);
    case 8:
        return __xchg_u64(ptr, x);
    }
    __xchg_called_with_bad_pointer();
    return x;
}


static __inline__ unsigned long
__cmpxchg_u32(volatile int *p, int old, int new)
{
    unsigned int prev;

    __asm__ __volatile__ (
    EIEIO_ON_SMP
"1: lwarx   %0,0,%2     # __cmpxchg_u32\n\
    cmpw    0,%0,%3\n\
    bne-    2f\n\
    stwcx.  %4,0,%2\n\
    bne-    1b"
    ISYNC_ON_SMP
    "\n\
2:"
    : "=&r" (prev), "=m" (*p)
    : "r" (p), "r" (old), "r" (new), "m" (*p)
    : "cc", "memory");

    return prev;
}

static __inline__ unsigned long
__cmpxchg_u64(volatile long *p, unsigned long old, unsigned long new)
{
    unsigned long prev;

    __asm__ __volatile__ (
    EIEIO_ON_SMP
"1: ldarx   %0,0,%2     # __cmpxchg_u64\n\
    cmpd    0,%0,%3\n\
    bne-    2f\n\
    stdcx.  %4,0,%2\n\
    bne-    1b"
    ISYNC_ON_SMP
    "\n\
2:"
    : "=&r" (prev), "=m" (*p)
    : "r" (p), "r" (old), "r" (new), "m" (*p)
    : "cc", "memory");

    return prev;
}

/* This function doesn't exist, so you'll get a linker error
   if something tries to do an invalid cmpxchg().  */
extern void __cmpxchg_called_with_bad_pointer(void);

static always_inline unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
{
    switch (size) {
    case 2:
        BUG(); return 0; /* XXX implement __cmpxchg_u16 ? */
    case 4:
        return __cmpxchg_u32(ptr, old, new);
    case 8:
        return __cmpxchg_u64(ptr, old, new);
    }
    __cmpxchg_called_with_bad_pointer();
    return old;
}

#define cmpxchg_user(ptr,o,n) cmpxchg(ptr,o,n)

#define cmpxchg(ptr,o,n)                         \
  ({                                     \
     __typeof__(*(ptr)) _o_ = (o);                   \
     __typeof__(*(ptr)) _n_ = (n);                   \
     (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,       \
                    (unsigned long)_n_, sizeof(*(ptr))); \
  })


/*  
 * Memory barrier.
 * The sync instruction guarantees that all memory accesses initiated
 * by this processor have been performed (with respect to all other
 * mechanisms that access memory).  The eieio instruction is a barrier
 * providing an ordering (separately) for (a) cacheable stores and (b)
 * loads and stores to non-cacheable memory (e.g. I/O devices).
 *
 * mb() prevents loads and stores being reordered across this point.
 * rmb() prevents loads being reordered across this point.
 * wmb() prevents stores being reordered across this point.
 * read_barrier_depends() prevents data-dependent loads being reordered
 *  across this point (nop on PPC).
 *
 * We have to use the sync instructions for mb(), since lwsync doesn't
 * order loads with respect to previous stores.  Lwsync is fine for
 * rmb(), though.
 * For wmb(), we use sync since wmb is used in drivers to order
 * stores to system memory with respect to writes to the device.
 * However, smp_wmb() can be a lighter-weight eieio barrier on
 * SMP since it is only used to order updates to system memory.
 */ 
#define mb()   __asm__ __volatile__ ("sync" : : : "memory")
#define rmb()  __asm__ __volatile__ ("lwsync" : : : "memory")
#define wmb()  __asm__ __volatile__ ("sync" : : : "memory")
#define read_barrier_depends()  do { } while(0)

#define set_mb(var, value)  do { var = value; smp_mb(); } while (0)
#define set_wmb(var, value) do { var = value; smp_wmb(); } while (0)

#ifdef CONFIG_SMP
#define smp_mb()    mb()
#define smp_rmb()   rmb()
#define smp_wmb()   __asm__ __volatile__ ("eieio" : : : "memory")
#define smp_read_barrier_depends()  read_barrier_depends()
#else 
#define smp_mb()    __asm__ __volatile__("": : :"memory")
#define smp_rmb()   __asm__ __volatile__("": : :"memory")
#define smp_wmb()   __asm__ __volatile__("": : :"memory")
#define smp_read_barrier_depends()  do { } while(0)
#endif /* CONFIG_SMP */

#define local_save_flags(flags) ((flags) = mfmsr())
#define local_irq_restore(flags) do { \
        __asm__ __volatile__("": : :"memory"); \
        mtmsrd((flags)); \
} while(0)

static inline void local_irq_disable(void)
{
        unsigned long msr;
        msr = mfmsr();
        mtmsrd(msr & ~MSR_EE);
        __asm__ __volatile__("" : : : "memory");
}

static inline void local_irq_enable(void)
{
        unsigned long msr;
        __asm__ __volatile__("" : : : "memory");
        msr = mfmsr();
        mtmsrd(msr | MSR_EE);
}

static inline void __do_save_and_cli(unsigned long *flags)
{
    unsigned long msr;
    msr = mfmsr();
    *flags = msr;
    mtmsrd(msr & ~MSR_EE);
    __asm__ __volatile__("" : : : "memory");
}

#define local_irq_save(flags) __do_save_and_cli(&flags)

static inline int local_irq_is_enabled(void)
{
    return !!(mfmsr() & MSR_EE);
}

#endif