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