LXR linux/arch/xtensa/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 start of the consistent memory region upwards.
  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 */
  37enum fixed_addresses {
  38#ifdef CONFIG_HIGHMEM
  39        /* reserved pte's for temporary kernel mappings */
  40        FIX_KMAP_BEGIN,
  41        FIX_KMAP_END = FIX_KMAP_BEGIN +
  42                (KM_TYPE_NR * NR_CPUS * DCACHE_N_COLORS) - 1,
  43#endif
  44        __end_of_fixed_addresses
  45};
  46
  47#define FIXADDR_TOP     (VMALLOC_START - PAGE_SIZE)
  48#define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  49#define FIXADDR_START   ((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)
  50
  51#define __fix_to_virt(x)        (FIXADDR_START + ((x) << PAGE_SHIFT))
  52#define __virt_to_fix(x)        (((x) - FIXADDR_START) >> PAGE_SHIFT)
  53
  54#ifndef __ASSEMBLY__
  55/*
  56 * 'index to address' translation. If anyone tries to use the idx
  57 * directly without translation, we catch the bug with a NULL-deference
  58 * kernel oops. Illegal ranges of incoming indices are caught too.
  59 */
  60static __always_inline unsigned long fix_to_virt(const unsigned int idx)
  61{
  62        /* Check if this memory layout is broken because fixmap overlaps page
  63         * table.
  64         */
  65        BUILD_BUG_ON(FIXADDR_START <
  66                     XCHAL_PAGE_TABLE_VADDR + XCHAL_PAGE_TABLE_SIZE);
  67        BUILD_BUG_ON(idx >= __end_of_fixed_addresses);
  68        return __fix_to_virt(idx);
  69}
  70
  71static inline unsigned long virt_to_fix(const unsigned long vaddr)
  72{
  73        BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
  74        return __virt_to_fix(vaddr);
  75}
  76
  77#endif
  78
  79#define kmap_get_fixmap_pte(vaddr) \
  80        pte_offset_kernel( \
  81                pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \
  82                (vaddr) \
  83        )
  84
  85#endif
  86