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  */
  37 enum 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  */
  60 static __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
  71 static 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