LXR linux/arch/um/include/asm/fixmap.h

   1#ifndef __UM_FIXMAP_H
   2#define __UM_FIXMAP_H
   3
   4#include <asm/processor.h>
   5#include <asm/system.h>
   6#include <asm/kmap_types.h>
   7#include <asm/archparam.h>
   8#include <asm/page.h>
   9#include <linux/threads.h>
  10
  11/*
  12 * Here we define all the compile-time 'special' virtual
  13 * addresses. The point is to have a constant address at
  14 * compile time, but to set the physical address only
  15 * in the boot process. We allocate these special  addresses
  16 * from the end of virtual memory (0xfffff000) backwards.
  17 * Also this lets us do fail-safe vmalloc(), we
  18 * can guarantee that these special addresses and
  19 * vmalloc()-ed addresses never overlap.
  20 *
  21 * these 'compile-time allocated' memory buffers are
  22 * fixed-size 4k pages. (or larger if used with an increment
  23 * highger than 1) use fixmap_set(idx,phys) to associate
  24 * physical memory with fixmap indices.
  25 *
  26 * TLB entries of such buffers will not be flushed across
  27 * task switches.
  28 */
  29
  30/*
  31 * on UP currently we will have no trace of the fixmap mechanizm,
  32 * no page table allocations, etc. This might change in the
  33 * future, say framebuffers for the console driver(s) could be
  34 * fix-mapped?
  35 */
  36enum fixed_addresses {
  37#ifdef CONFIG_HIGHMEM
  38        FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
  39        FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
  40#endif
  41        __end_of_fixed_addresses
  42};
  43
  44extern void __set_fixmap (enum fixed_addresses idx,
  45                          unsigned long phys, pgprot_t flags);
  46
  47#define set_fixmap(idx, phys) \
  48                __set_fixmap(idx, phys, PAGE_KERNEL)
  49/*
  50 * Some hardware wants to get fixmapped without caching.
  51 */
  52#define set_fixmap_nocache(idx, phys) \
  53                __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
  54/*
  55 * used by vmalloc.c.
  56 *
  57 * Leave one empty page between vmalloc'ed areas and
  58 * the start of the fixmap, and leave one page empty
  59 * at the top of mem..
  60 */
  61
  62#define FIXADDR_TOP     (TASK_SIZE - 2 * PAGE_SIZE)
  63#define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  64#define FIXADDR_START   (FIXADDR_TOP - FIXADDR_SIZE)
  65
  66#define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
  67#define __virt_to_fix(x)      ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
  68
  69extern void __this_fixmap_does_not_exist(void);
  70
  71/*
  72 * 'index to address' translation. If anyone tries to use the idx
  73 * directly without tranlation, we catch the bug with a NULL-deference
  74 * kernel oops. Illegal ranges of incoming indices are caught too.
  75 */
  76static inline unsigned long fix_to_virt(const unsigned int idx)
  77{
  78        /*
  79         * this branch gets completely eliminated after inlining,
  80         * except when someone tries to use fixaddr indices in an
  81         * illegal way. (such as mixing up address types or using
  82         * out-of-range indices).
  83         *
  84         * If it doesn't get removed, the linker will complain
  85         * loudly with a reasonably clear error message..
  86         */
  87        if (idx >= __end_of_fixed_addresses)
  88                __this_fixmap_does_not_exist();
  89
  90        return __fix_to_virt(idx);
  91}
  92
  93static inline unsigned long virt_to_fix(const unsigned long vaddr)
  94{
  95      BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
  96      return __virt_to_fix(vaddr);
  97}
  98
  99#endif
 100