root/include/asm-x86/fixmap.h

INCLUDED FROM

DEFINITIONS

1. __set_fixmap
2. fix_to_virt
3. virt_to_fix

#ifndef ASM_X86__FIXMAP_H
#define ASM_X86__FIXMAP_H

#ifdef CONFIG_X86_32
# include "fixmap_32.h"
#else
# include "fixmap_64.h"
#endif

extern int fixmaps_set;

void __native_set_fixmap(enum fixed_addresses idx, pte_t pte);
void native_set_fixmap(enum fixed_addresses idx,
                       unsigned long phys, pgprot_t flags);

#ifndef CONFIG_PARAVIRT
static inline void __set_fixmap(enum fixed_addresses idx,
                                unsigned long phys, pgprot_t flags)
{
        native_set_fixmap(idx, phys, flags);
}
#endif

#define set_fixmap(idx, phys)                           \
        __set_fixmap(idx, phys, PAGE_KERNEL)

/*
 * Some hardware wants to get fixmapped without caching.
 */
#define set_fixmap_nocache(idx, phys)                   \
        __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)

#define clear_fixmap(idx)                       \
        __set_fixmap(idx, 0, __pgprot(0))

#define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
#define __virt_to_fix(x)        ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)

extern void __this_fixmap_does_not_exist(void);

/*
 * 'index to address' translation. If anyone tries to use the idx
 * directly without translation, we catch the bug with a NULL-deference
 * kernel oops. Illegal ranges of incoming indices are caught too.
 */
static __always_inline unsigned long fix_to_virt(const unsigned int idx)
{
        /*
         * this branch gets completely eliminated after inlining,
         * except when someone tries to use fixaddr indices in an
         * illegal way. (such as mixing up address types or using
         * out-of-range indices).
         *
         * If it doesn't get removed, the linker will complain
         * loudly with a reasonably clear error message..
         */
        if (idx >= __end_of_fixed_addresses)
                __this_fixmap_does_not_exist();

        return __fix_to_virt(idx);
}

static inline unsigned long virt_to_fix(const unsigned long vaddr)
{
        BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
        return __virt_to_fix(vaddr);
}
#endif /* ASM_X86__FIXMAP_H */