mm/mlock.c

   1 /*
   2  *      linux/mm/mlock.c
   3  *
   4  *  (C) Copyright 1995 Linus Torvalds
   5  *  (C) Copyright 2002 Christoph Hellwig
   6  */
   7
   8 #include <linux/mman.h>
   9 #include <linux/mm.h>
  10
  11
  12 static int mlock_fixup(struct vm_area_struct * vma,
  13         unsigned long start, unsigned long end, unsigned int newflags)
  14 {
  15         struct mm_struct * mm = vma->vm_mm;
  16         int pages;
  17         int ret = 0;
  18
  19         if (newflags == vma->vm_flags)
  20                 goto out;
  21
  22         if (start != vma->vm_start) {
  23                 if (split_vma(mm, vma, start, 1)) {
  24                         ret = -EAGAIN;
  25                         goto out;
  26                 }
  27         }
  28
  29         if (end != vma->vm_end) {
  30                 if (split_vma(mm, vma, end, 0)) {
  31                         ret = -EAGAIN;
  32                         goto out;
  33                 }
  34         }
  35
  36         spin_lock(&mm->page_table_lock);
  37         vma->vm_flags = newflags;
  38         spin_unlock(&mm->page_table_lock);
  39
  40         /*
  41          * Keep track of amount of locked VM.
  42          */
  43         pages = (end - start) >> PAGE_SHIFT;
  44         if (newflags & VM_LOCKED) {
  45                 pages = -pages;
  46                 ret = make_pages_present(start, end);
  47         }
  48
  49         vma->vm_mm->locked_vm -= pages;
  50 out:
  51         return ret;
  52 }
  53
  54 static int do_mlock(unsigned long start, size_t len, int on)
  55 {
  56         unsigned long nstart, end, tmp;
  57         struct vm_area_struct * vma, * next;
  58         int error;
  59
  60         if (on && !capable(CAP_IPC_LOCK))
  61                 return -EPERM;
  62         len = PAGE_ALIGN(len);
  63         end = start + len;
  64         if (end < start)
  65                 return -EINVAL;
  66         if (end == start)
  67                 return 0;
  68         vma = find_vma(current->mm, start);
  69         if (!vma || vma->vm_start > start)
  70                 return -ENOMEM;
  71
  72         for (nstart = start ; ; ) {
  73                 unsigned int newflags;
  74
  75                 /* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
  76
  77                 newflags = vma->vm_flags | VM_LOCKED;
  78                 if (!on)
  79                         newflags &= ~VM_LOCKED;
  80
  81                 if (vma->vm_end >= end) {
  82                         error = mlock_fixup(vma, nstart, end, newflags);
  83                         break;
  84                 }
  85
  86                 tmp = vma->vm_end;
  87                 next = vma->vm_next;
  88                 error = mlock_fixup(vma, nstart, tmp, newflags);
  89                 if (error)
  90                         break;
  91                 nstart = tmp;
  92                 vma = next;
  93                 if (!vma || vma->vm_start != nstart) {
  94                         error = -ENOMEM;
  95                         break;
  96                 }
  97         }
  98         return error;
  99 }
 100
 101 asmlinkage long sys_mlock(unsigned long start, size_t len)
 102 {
 103         unsigned long locked;
 104         unsigned long lock_limit;
 105         int error = -ENOMEM;
 106
 107         down_write(&current->mm->mmap_sem);
 108         len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
 109         start &= PAGE_MASK;
 110
 111         locked = len >> PAGE_SHIFT;
 112         locked += current->mm->locked_vm;
 113
 114         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 115         lock_limit >>= PAGE_SHIFT;
 116
 117         /* check against resource limits */
 118         if (locked <= lock_limit)
 119                 error = do_mlock(start, len, 1);
 120         up_write(&current->mm->mmap_sem);
 121         return error;
 122 }
 123
 124 asmlinkage long sys_munlock(unsigned long start, size_t len)
 125 {
 126         int ret;
 127
 128         down_write(&current->mm->mmap_sem);
 129         len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
 130         start &= PAGE_MASK;
 131         ret = do_mlock(start, len, 0);
 132         up_write(&current->mm->mmap_sem);
 133         return ret;
 134 }
 135
 136 static int do_mlockall(int flags)
 137 {
 138         int error;
 139         unsigned int def_flags;
 140         struct vm_area_struct * vma;
 141
 142         if (!capable(CAP_IPC_LOCK))
 143                 return -EPERM;
 144
 145         def_flags = 0;
 146         if (flags & MCL_FUTURE)
 147                 def_flags = VM_LOCKED;
 148         current->mm->def_flags = def_flags;
 149
 150         error = 0;
 151         for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
 152                 unsigned int newflags;
 153
 154                 newflags = vma->vm_flags | VM_LOCKED;
 155                 if (!(flags & MCL_CURRENT))
 156                         newflags &= ~VM_LOCKED;
 157
 158                 /* Ignore errors */
 159                 mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
 160         }
 161         return error;
 162 }
 163
 164 asmlinkage long sys_mlockall(int flags)
 165 {
 166         unsigned long lock_limit;
 167         int ret = -EINVAL;
 168
 169         down_write(&current->mm->mmap_sem);
 170         if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
 171                 goto out;
 172
 173         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 174         lock_limit >>= PAGE_SHIFT;
 175
 176         ret = -ENOMEM;
 177         if (current->mm->total_vm <= lock_limit)
 178                 ret = do_mlockall(flags);
 179 out:
 180         up_write(&current->mm->mmap_sem);
 181         return ret;
 182 }
 183
 184 asmlinkage long sys_munlockall(void)
 185 {
 186         int ret;
 187
 188         down_write(&current->mm->mmap_sem);
 189         ret = do_mlockall(0);
 190         up_write(&current->mm->mmap_sem);
 191         return ret;
 192 }