arch/arm/mm/mmap.c

   1 /*
   2  *  linux/arch/arm/mm/mmap.c
   3  */
   4 #include <linux/fs.h>
   5 #include <linux/mm.h>
   6 #include <linux/mman.h>
   7 #include <linux/shm.h>
   8 #include <linux/sched.h>
   9 #include <linux/io.h>
  10 #include <asm/cputype.h>
  11 #include <asm/system.h>
  12
  13 #define COLOUR_ALIGN(addr,pgoff)                \
  14         ((((addr)+SHMLBA-1)&~(SHMLBA-1)) +      \
  15          (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
  16
  17 /*
  18  * We need to ensure that shared mappings are correctly aligned to
  19  * avoid aliasing issues with VIPT caches.  We need to ensure that
  20  * a specific page of an object is always mapped at a multiple of
  21  * SHMLBA bytes.
  22  *
  23  * We unconditionally provide this function for all cases, however
  24  * in the VIVT case, we optimise out the alignment rules.
  25  */
  26 unsigned long
  27 arch_get_unmapped_area(struct file *filp, unsigned long addr,
  28                 unsigned long len, unsigned long pgoff, unsigned long flags)
  29 {
  30         struct mm_struct *mm = current->mm;
  31         struct vm_area_struct *vma;
  32         unsigned long start_addr;
  33 #ifdef CONFIG_CPU_V6
  34         unsigned int cache_type;
  35         int do_align = 0, aliasing = 0;
  36
  37         /*
  38          * We only need to do colour alignment if either the I or D
  39          * caches alias.  This is indicated by bits 9 and 21 of the
  40          * cache type register.
  41          */
  42         cache_type = read_cpuid_cachetype();
  43         if (cache_type != read_cpuid_id()) {
  44                 aliasing = (cache_type | cache_type >> 12) & (1 << 11);
  45                 if (aliasing)
  46                         do_align = filp || flags & MAP_SHARED;
  47         }
  48 #else
  49 #define do_align 0
  50 #define aliasing 0
  51 #endif
  52
  53         /*
  54          * We enforce the MAP_FIXED case.
  55          */
  56         if (flags & MAP_FIXED) {
  57                 if (aliasing && flags & MAP_SHARED && addr & (SHMLBA - 1))
  58                         return -EINVAL;
  59                 return addr;
  60         }
  61
  62         if (len > TASK_SIZE)
  63                 return -ENOMEM;
  64
  65         if (addr) {
  66                 if (do_align)
  67                         addr = COLOUR_ALIGN(addr, pgoff);
  68                 else
  69                         addr = PAGE_ALIGN(addr);
  70
  71                 vma = find_vma(mm, addr);
  72                 if (TASK_SIZE - len >= addr &&
  73                     (!vma || addr + len <= vma->vm_start))
  74                         return addr;
  75         }
  76         if (len > mm->cached_hole_size) {
  77                 start_addr = addr = mm->free_area_cache;
  78         } else {
  79                 start_addr = addr = TASK_UNMAPPED_BASE;
  80                 mm->cached_hole_size = 0;
  81         }
  82
  83 full_search:
  84         if (do_align)
  85                 addr = COLOUR_ALIGN(addr, pgoff);
  86         else
  87                 addr = PAGE_ALIGN(addr);
  88
  89         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
  90                 /* At this point:  (!vma || addr < vma->vm_end). */
  91                 if (TASK_SIZE - len < addr) {
  92                         /*
  93                          * Start a new search - just in case we missed
  94                          * some holes.
  95                          */
  96                         if (start_addr != TASK_UNMAPPED_BASE) {
  97                                 start_addr = addr = TASK_UNMAPPED_BASE;
  98                                 mm->cached_hole_size = 0;
  99                                 goto full_search;
 100                         }
 101                         return -ENOMEM;
 102                 }
 103                 if (!vma || addr + len <= vma->vm_start) {
 104                         /*
 105                          * Remember the place where we stopped the search:
 106                          */
 107                         mm->free_area_cache = addr + len;
 108                         return addr;
 109                 }
 110                 if (addr + mm->cached_hole_size < vma->vm_start)
 111                         mm->cached_hole_size = vma->vm_start - addr;
 112                 addr = vma->vm_end;
 113                 if (do_align)
 114                         addr = COLOUR_ALIGN(addr, pgoff);
 115         }
 116 }
 117
 118
 119 /*
 120  * You really shouldn't be using read() or write() on /dev/mem.  This
 121  * might go away in the future.
 122  */
 123 int valid_phys_addr_range(unsigned long addr, size_t size)
 124 {
 125         if (addr < PHYS_OFFSET)
 126                 return 0;
 127         if (addr + size > __pa(high_memory))
 128                 return 0;
 129
 130         return 1;
 131 }
 132
 133 /*
 134  * We don't use supersection mappings for mmap() on /dev/mem, which
 135  * means that we can't map the memory area above the 4G barrier into
 136  * userspace.
 137  */
 138 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 139 {
 140         return !(pfn + (size >> PAGE_SHIFT) > 0x00100000);
 141 }