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 &&
  58                     (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
  59                         return -EINVAL;
  60                 return addr;
  61         }
  62
  63         if (len > TASK_SIZE)
  64                 return -ENOMEM;
  65
  66         if (addr) {
  67                 if (do_align)
  68                         addr = COLOUR_ALIGN(addr, pgoff);
  69                 else
  70                         addr = PAGE_ALIGN(addr);
  71
  72                 vma = find_vma(mm, addr);
  73                 if (TASK_SIZE - len >= addr &&
  74                     (!vma || addr + len <= vma->vm_start))
  75                         return addr;
  76         }
  77         if (len > mm->cached_hole_size) {
  78                 start_addr = addr = mm->free_area_cache;
  79         } else {
  80                 start_addr = addr = TASK_UNMAPPED_BASE;
  81                 mm->cached_hole_size = 0;
  82         }
  83
  84 full_search:
  85         if (do_align)
  86                 addr = COLOUR_ALIGN(addr, pgoff);
  87         else
  88                 addr = PAGE_ALIGN(addr);
  89
  90         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
  91                 /* At this point:  (!vma || addr < vma->vm_end). */
  92                 if (TASK_SIZE - len < addr) {
  93                         /*
  94                          * Start a new search - just in case we missed
  95                          * some holes.
  96                          */
  97                         if (start_addr != TASK_UNMAPPED_BASE) {
  98                                 start_addr = addr = TASK_UNMAPPED_BASE;
  99                                 mm->cached_hole_size = 0;
 100                                 goto full_search;
 101                         }
 102                         return -ENOMEM;
 103                 }
 104                 if (!vma || addr + len <= vma->vm_start) {
 105                         /*
 106                          * Remember the place where we stopped the search:
 107                          */
 108                         mm->free_area_cache = addr + len;
 109                         return addr;
 110                 }
 111                 if (addr + mm->cached_hole_size < vma->vm_start)
 112                         mm->cached_hole_size = vma->vm_start - addr;
 113                 addr = vma->vm_end;
 114                 if (do_align)
 115                         addr = COLOUR_ALIGN(addr, pgoff);
 116         }
 117 }
 118
 119
 120 /*
 121  * You really shouldn't be using read() or write() on /dev/mem.  This
 122  * might go away in the future.
 123  */
 124 int valid_phys_addr_range(unsigned long addr, size_t size)
 125 {
 126         if (addr < PHYS_OFFSET)
 127                 return 0;
 128         if (addr + size > __pa(high_memory - 1) + 1)
 129                 return 0;
 130
 131         return 1;
 132 }
 133
 134 /*
 135  * We don't use supersection mappings for mmap() on /dev/mem, which
 136  * means that we can't map the memory area above the 4G barrier into
 137  * userspace.
 138  */
 139 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 140 {
 141         return !(pfn + (size >> PAGE_SHIFT) > 0x00100000);
 142 }