arch/sh/mm/mmap.c

   1 /*
   2  * arch/sh/mm/mmap.c
   3  *
   4  * Copyright (C) 2008 - 2009  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 static inline unsigned long COLOUR_ALIGN(unsigned long addr,
  25                                          unsigned long pgoff)
  26 {
  27         unsigned long base = (addr + shm_align_mask) & ~shm_align_mask;
  28         unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;
  29
  30         return base + off;
  31 }
  32
  33 static inline unsigned long COLOUR_ALIGN_DOWN(unsigned long addr,
  34                                               unsigned long pgoff)
  35 {
  36         unsigned long base = addr & ~shm_align_mask;
  37         unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;
  38
  39         if (base + off <= addr)
  40                 return base + off;
  41
  42         return base - off;
  43 }
  44
  45 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
  46         unsigned long len, unsigned long pgoff, unsigned long flags)
  47 {
  48         struct mm_struct *mm = current->mm;
  49         struct vm_area_struct *vma;
  50         unsigned long start_addr;
  51         int do_colour_align;
  52
  53         if (flags & MAP_FIXED) {
  54                 /* We do not accept a shared mapping if it would violate
  55                  * cache aliasing constraints.
  56                  */
  57                 if ((flags & MAP_SHARED) && (addr & shm_align_mask))
  58                         return -EINVAL;
  59                 return addr;
  60         }
  61
  62         if (unlikely(len > TASK_SIZE))
  63                 return -ENOMEM;
  64
  65         do_colour_align = 0;
  66         if (filp || (flags & MAP_SHARED))
  67                 do_colour_align = 1;
  68
  69         if (addr) {
  70                 if (do_colour_align)
  71                         addr = COLOUR_ALIGN(addr, pgoff);
  72                 else
  73                         addr = PAGE_ALIGN(addr);
  74
  75                 vma = find_vma(mm, addr);
  76                 if (TASK_SIZE - len >= addr &&
  77                     (!vma || addr + len <= vma->vm_start))
  78                         return addr;
  79         }
  80
  81         if (len > mm->cached_hole_size) {
  82                 start_addr = addr = mm->free_area_cache;
  83         } else {
  84                 mm->cached_hole_size = 0;
  85                 start_addr = addr = TASK_UNMAPPED_BASE;
  86         }
  87
  88 full_search:
  89         if (do_colour_align)
  90                 addr = COLOUR_ALIGN(addr, pgoff);
  91         else
  92                 addr = PAGE_ALIGN(mm->free_area_cache);
  93
  94         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
  95                 /* At this point:  (!vma || addr < vma->vm_end). */
  96                 if (unlikely(TASK_SIZE - len < addr)) {
  97                         /*
  98                          * Start a new search - just in case we missed
  99                          * some holes.
 100                          */
 101                         if (start_addr != TASK_UNMAPPED_BASE) {
 102                                 start_addr = addr = TASK_UNMAPPED_BASE;
 103                                 mm->cached_hole_size = 0;
 104                                 goto full_search;
 105                         }
 106                         return -ENOMEM;
 107                 }
 108                 if (likely(!vma || addr + len <= vma->vm_start)) {
 109                         /*
 110                          * Remember the place where we stopped the search:
 111                          */
 112                         mm->free_area_cache = addr + len;
 113                         return addr;
 114                 }
 115                 if (addr + mm->cached_hole_size < vma->vm_start)
 116                         mm->cached_hole_size = vma->vm_start - addr;
 117
 118                 addr = vma->vm_end;
 119                 if (do_colour_align)
 120                         addr = COLOUR_ALIGN(addr, pgoff);
 121         }
 122 }
 123
 124 unsigned long
 125 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 126                           const unsigned long len, const unsigned long pgoff,
 127                           const unsigned long flags)
 128 {
 129         struct vm_area_struct *vma;
 130         struct mm_struct *mm = current->mm;
 131         unsigned long addr = addr0;
 132         int do_colour_align;
 133
 134         if (flags & MAP_FIXED) {
 135                 /* We do not accept a shared mapping if it would violate
 136                  * cache aliasing constraints.
 137                  */
 138                 if ((flags & MAP_SHARED) &&
 139                     ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
 140                         return -EINVAL;
 141                 return addr;
 142         }
 143
 144         if (unlikely(len > TASK_SIZE))
 145                 return -ENOMEM;
 146
 147         do_colour_align = 0;
 148         if (filp || (flags & MAP_SHARED))
 149                 do_colour_align = 1;
 150
 151         /* requesting a specific address */
 152         if (addr) {
 153                 if (do_colour_align)
 154                         addr = COLOUR_ALIGN(addr, pgoff);
 155                 else
 156                         addr = PAGE_ALIGN(addr);
 157
 158                 vma = find_vma(mm, addr);
 159                 if (TASK_SIZE - len >= addr &&
 160                     (!vma || addr + len <= vma->vm_start))
 161                         return addr;
 162         }
 163
 164         /* check if free_area_cache is useful for us */
 165         if (len <= mm->cached_hole_size) {
 166                 mm->cached_hole_size = 0;
 167                 mm->free_area_cache = mm->mmap_base;
 168         }
 169
 170         /* either no address requested or can't fit in requested address hole */
 171         addr = mm->free_area_cache;
 172         if (do_colour_align) {
 173                 unsigned long base = COLOUR_ALIGN_DOWN(addr-len, pgoff);
 174
 175                 addr = base + len;
 176         }
 177
 178         /* make sure it can fit in the remaining address space */
 179         if (likely(addr > len)) {
 180                 vma = find_vma(mm, addr-len);
 181                 if (!vma || addr <= vma->vm_start) {
 182                         /* remember the address as a hint for next time */
 183                         return (mm->free_area_cache = addr-len);
 184                 }
 185         }
 186
 187         if (unlikely(mm->mmap_base < len))
 188                 goto bottomup;
 189
 190         addr = mm->mmap_base-len;
 191         if (do_colour_align)
 192                 addr = COLOUR_ALIGN_DOWN(addr, pgoff);
 193
 194         do {
 195                 /*
 196                  * Lookup failure means no vma is above this address,
 197                  * else if new region fits below vma->vm_start,
 198                  * return with success:
 199                  */
 200                 vma = find_vma(mm, addr);
 201                 if (likely(!vma || addr+len <= vma->vm_start)) {
 202                         /* remember the address as a hint for next time */
 203                         return (mm->free_area_cache = addr);
 204                 }
 205
 206                 /* remember the largest hole we saw so far */
 207                 if (addr + mm->cached_hole_size < vma->vm_start)
 208                         mm->cached_hole_size = vma->vm_start - addr;
 209
 210                 /* try just below the current vma->vm_start */
 211                 addr = vma->vm_start-len;
 212                 if (do_colour_align)
 213                         addr = COLOUR_ALIGN_DOWN(addr, pgoff);
 214         } while (likely(len < vma->vm_start));
 215
 216 bottomup:
 217         /*
 218          * A failed mmap() very likely causes application failure,
 219          * so fall back to the bottom-up function here. This scenario
 220          * can happen with large stack limits and large mmap()
 221          * allocations.
 222          */
 223         mm->cached_hole_size = ~0UL;
 224         mm->free_area_cache = TASK_UNMAPPED_BASE;
 225         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 226         /*
 227          * Restore the topdown base:
 228          */
 229         mm->free_area_cache = mm->mmap_base;
 230         mm->cached_hole_size = ~0UL;
 231
 232         return addr;
 233 }
 234 #endif /* CONFIG_MMU */
 235
 236 /*
 237  * You really shouldn't be using read() or write() on /dev/mem.  This
 238  * might go away in the future.
 239  */
 240 int valid_phys_addr_range(unsigned long addr, size_t count)
 241 {
 242         if (addr < __MEMORY_START)
 243                 return 0;
 244         if (addr + count > __pa(high_memory))
 245                 return 0;
 246
 247         return 1;
 248 }
 249
 250 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 251 {
 252         return 1;
 253 }