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

   1/*
   2 * fixmap.h: compile-time virtual memory allocation
   3 *
   4 * This file is subject to the terms and conditions of the GNU General Public
   5 * License.  See the file "COPYING" in the main directory of this archive
   6 * for more details.
   7 *
   8 * Copyright (C) 1998 Ingo Molnar
   9 *
  10 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
  11 */
  12
  13#ifndef _ASM_FIXMAP_H
  14#define _ASM_FIXMAP_H
  15
  16#include <asm/pgtable.h>
  17#ifdef CONFIG_HIGHMEM
  18#include <linux/threads.h>
  19#include <asm/kmap_types.h>
  20#endif
  21
  22/*
  23 * Here we define all the compile-time 'special' virtual
  24 * addresses. The point is to have a constant address at
  25 * compile time, but to set the physical address only
  26 * in the boot process. We allocate these special  addresses
  27 * from the end of the consistent memory region backwards.
  28 * Also this lets us do fail-safe vmalloc(), we
  29 * can guarantee that these special addresses and
  30 * vmalloc()-ed addresses never overlap.
  31 *
  32 * these 'compile-time allocated' memory buffers are
  33 * fixed-size 4k pages. (or larger if used with an increment
  34 * higher than 1) use fixmap_set(idx,phys) to associate
  35 * physical memory with fixmap indices.
  36 *
  37 * TLB entries of such buffers will not be flushed across
  38 * task switches.
  39 */
  40enum fixed_addresses {
  41#define FIX_N_COLOURS 8
  42#ifdef CONFIG_HIGHMEM
  43        /* reserved pte's for temporary kernel mappings */
  44        FIX_KMAP_BEGIN,
  45        FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
  46#endif
  47        __end_of_fixed_addresses
  48};
  49
  50#define FIXADDR_TOP     (CONSISTENT_START - PAGE_SIZE)
  51#define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  52#define FIXADDR_START   ((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)
  53
  54#define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
  55#define __virt_to_fix(x)        ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
  56
  57extern void __this_fixmap_does_not_exist(void);
  58/*
  59 * 'index to address' translation. If anyone tries to use the idx
  60 * directly without tranlation, we catch the bug with a NULL-deference
  61 * kernel oops. Illegal ranges of incoming indices are caught too.
  62 */
  63static inline unsigned long fix_to_virt(const unsigned int idx)
  64{
  65        /*
  66         * this branch gets completely eliminated after inlining,
  67         * except when someone tries to use fixaddr indices in an
  68         * illegal way. (such as mixing up address types or using
  69         * out-of-range indices).
  70         *
  71         * If it doesn't get removed, the linker will complain
  72         * loudly with a reasonably clear error message..
  73         */
  74        if (idx >= __end_of_fixed_addresses)
  75                __this_fixmap_does_not_exist();
  76
  77        return __fix_to_virt(idx);
  78}
  79
  80static inline unsigned long virt_to_fix(const unsigned long vaddr)
  81{
  82        BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
  83        return __virt_to_fix(vaddr);
  84}
  85
  86#define kmap_get_fixmap_pte(vaddr) \
  87        pte_offset_kernel( \
  88                pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \
  89                (vaddr) \
  90        )
  91
  92/*
  93 * Called from pgtable_init()
  94 */
  95extern void fixrange_init(unsigned long start, unsigned long end,
  96        pgd_t *pgd_base);
  97
  98
  99#endif
 100