arch/sh/mm/mmap.c

   1 /*
   2  * arch/sh/mm/mmap.c
   3  *
   4  * Copyright (C) 2008  Paul Mundt
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10 #include <linux/io.h>
  11 #include <linux/mm.h>
  12 #include <linux/mman.h>
  13 #include <linux/module.h>
  14 #include <asm/page.h>
  15 #include <asm/processor.h>
  16
  17 #ifdef CONFIG_MMU
  18 unsigned long shm_align_mask = PAGE_SIZE - 1;   /* Sane caches */
  19 EXPORT_SYMBOL(shm_align_mask);
  20
  21 /*
  22  * To avoid cache aliases, we map the shared page with same color.
  23  */
  24 #define COLOUR_ALIGN(addr, pgoff)                               \
  25         ((((addr) + shm_align_mask) & ~shm_align_mask) +        \
  26          (((pgoff) << PAGE_SHIFT) & shm_align_mask))
  27
  28 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
  29         unsigned long len, unsigned long pgoff, unsigned long flags)
  30 {
  31         struct mm_struct *mm = current->mm;
  32         struct vm_area_struct *vma;
  33         unsigned long start_addr;
  34         int do_colour_align;
  35
  36         if (flags & MAP_FIXED) {
  37                 /* We do not accept a shared mapping if it would violate
  38                  * cache aliasing constraints.
  39                  */
  40                 if ((flags & MAP_SHARED) && (addr & shm_align_mask))
  41                         return -EINVAL;
  42                 return addr;
  43         }
  44
  45         if (unlikely(len > TASK_SIZE))
  46                 return -ENOMEM;
  47
  48         do_colour_align = 0;
  49         if (filp || (flags & MAP_SHARED))
  50                 do_colour_align = 1;
  51
  52         if (addr) {
  53                 if (do_colour_align)
  54                         addr = COLOUR_ALIGN(addr, pgoff);
  55                 else
  56                         addr = PAGE_ALIGN(addr);
  57
  58                 vma = find_vma(mm, addr);
  59                 if (TASK_SIZE - len >= addr &&
  60                     (!vma || addr + len <= vma->vm_start))
  61                         return addr;
  62         }
  63
  64         if (len > mm->cached_hole_size) {
  65                 start_addr = addr = mm->free_area_cache;
  66         } else {
  67                 mm->cached_hole_size = 0;
  68                 start_addr = addr = TASK_UNMAPPED_BASE;
  69         }
  70
  71 full_search:
  72         if (do_colour_align)
  73                 addr = COLOUR_ALIGN(addr, pgoff);
  74         else
  75                 addr = PAGE_ALIGN(mm->free_area_cache);
  76
  77         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
  78                 /* At this point:  (!vma || addr < vma->vm_end). */
  79                 if (unlikely(TASK_SIZE - len < addr)) {
  80                         /*
  81                          * Start a new search - just in case we missed
  82                          * some holes.
  83                          */
  84                         if (start_addr != TASK_UNMAPPED_BASE) {
  85                                 start_addr = addr = TASK_UNMAPPED_BASE;
  86                                 mm->cached_hole_size = 0;
  87                                 goto full_search;
  88                         }
  89                         return -ENOMEM;
  90                 }
  91                 if (likely(!vma || addr + len <= vma->vm_start)) {
  92                         /*
  93                          * Remember the place where we stopped the search:
  94                          */
  95                         mm->free_area_cache = addr + len;
  96                         return addr;
  97                 }
  98                 if (addr + mm->cached_hole_size < vma->vm_start)
  99                         mm->cached_hole_size = vma->vm_start - addr;
 100
 101                 addr = vma->vm_end;
 102                 if (do_colour_align)
 103                         addr = COLOUR_ALIGN(addr, pgoff);
 104         }
 105 }
 106 #endif /* CONFIG_MMU */
 107
 108 /*
 109  * You really shouldn't be using read() or write() on /dev/mem.  This
 110  * might go away in the future.
 111  */
 112 int valid_phys_addr_range(unsigned long addr, size_t count)
 113 {
 114         if (addr < __MEMORY_START)
 115                 return 0;
 116         if (addr + count > __pa(high_memory))
 117                 return 0;
 118
 119         return 1;
 120 }
 121
 122 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 123 {
 124         return 1;
 125 }