mm/mlock.c

   1 /*
   2  *      linux/mm/mlock.c
   3  *
   4  *  (C) Copyright 1995 Linus Torvalds
   5  */
   6 #include <linux/slab.h>
   7 #include <linux/shm.h>
   8 #include <linux/mman.h>
   9 #include <linux/smp_lock.h>
  10
  11 #include <asm/uaccess.h>
  12 #include <asm/pgtable.h>
  13
  14 static inline int mlock_fixup_all(struct vm_area_struct * vma, int newflags)
  15 {
  16         vma->vm_flags = newflags;
  17         return 0;
  18 }
  19
  20 static inline int mlock_fixup_start(struct vm_area_struct * vma,
  21         unsigned long end, int newflags)
  22 {
  23         struct vm_area_struct * n;
  24
  25         n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
  26         if (!n)
  27                 return -EAGAIN;
  28         *n = *vma;
  29         vma->vm_start = end;
  30         n->vm_end = end;
  31         vma->vm_offset += vma->vm_start - n->vm_start;
  32         n->vm_flags = newflags;
  33         if (n->vm_file)
  34                 get_file(n->vm_file);
  35         if (n->vm_ops && n->vm_ops->open)
  36                 n->vm_ops->open(n);
  37         insert_vm_struct(current->mm, n);
  38         return 0;
  39 }
  40
  41 static inline int mlock_fixup_end(struct vm_area_struct * vma,
  42         unsigned long start, int newflags)
  43 {
  44         struct vm_area_struct * n;
  45
  46         n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
  47         if (!n)
  48                 return -EAGAIN;
  49         *n = *vma;
  50         vma->vm_end = start;
  51         n->vm_start = start;
  52         n->vm_offset += n->vm_start - vma->vm_start;
  53         n->vm_flags = newflags;
  54         if (n->vm_file)
  55                 get_file(n->vm_file);
  56         if (n->vm_ops && n->vm_ops->open)
  57                 n->vm_ops->open(n);
  58         insert_vm_struct(current->mm, n);
  59         return 0;
  60 }
  61
  62 static inline int mlock_fixup_middle(struct vm_area_struct * vma,
  63         unsigned long start, unsigned long end, int newflags)
  64 {
  65         struct vm_area_struct * left, * right;
  66
  67         left = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
  68         if (!left)
  69                 return -EAGAIN;
  70         right = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
  71         if (!right) {
  72                 kmem_cache_free(vm_area_cachep, left);
  73                 return -EAGAIN;
  74         }
  75         *left = *vma;
  76         *right = *vma;
  77         left->vm_end = start;
  78         vma->vm_start = start;
  79         vma->vm_end = end;
  80         right->vm_start = end;
  81         vma->vm_offset += vma->vm_start - left->vm_start;
  82         right->vm_offset += right->vm_start - left->vm_start;
  83         vma->vm_flags = newflags;
  84         if (vma->vm_file)
  85                 atomic_add(2, &vma->vm_file->f_count);
  86
  87         if (vma->vm_ops && vma->vm_ops->open) {
  88                 vma->vm_ops->open(left);
  89                 vma->vm_ops->open(right);
  90         }
  91         insert_vm_struct(current->mm, left);
  92         insert_vm_struct(current->mm, right);
  93         return 0;
  94 }
  95
  96 static int mlock_fixup(struct vm_area_struct * vma,
  97         unsigned long start, unsigned long end, unsigned int newflags)
  98 {
  99         int pages, retval;
 100
 101         if (newflags == vma->vm_flags)
 102                 return 0;
 103
 104         if (start == vma->vm_start) {
 105                 if (end == vma->vm_end)
 106                         retval = mlock_fixup_all(vma, newflags);
 107                 else
 108                         retval = mlock_fixup_start(vma, end, newflags);
 109         } else {
 110                 if (end == vma->vm_end)
 111                         retval = mlock_fixup_end(vma, start, newflags);
 112                 else
 113                         retval = mlock_fixup_middle(vma, start, end, newflags);
 114         }
 115         if (!retval) {
 116                 /* keep track of amount of locked VM */
 117                 pages = (end - start) >> PAGE_SHIFT;
 118                 if (newflags & VM_LOCKED) {
 119                         pages = -pages;
 120                         make_pages_present(start, end);
 121                 }
 122                 vma->vm_mm->locked_vm -= pages;
 123         }
 124         return retval;
 125 }
 126
 127 static int do_mlock(unsigned long start, size_t len, int on)
 128 {
 129         unsigned long nstart, end, tmp;
 130         struct vm_area_struct * vma, * next;
 131         int error;
 132
 133         if (!capable(CAP_IPC_LOCK))
 134                 return -EPERM;
 135         len = (len + ~PAGE_MASK) & PAGE_MASK;
 136         end = start + len;
 137         if (end < start)
 138                 return -EINVAL;
 139         if (end == start)
 140                 return 0;
 141         vma = find_vma(current->mm, start);
 142         if (!vma || vma->vm_start > start)
 143                 return -ENOMEM;
 144
 145         for (nstart = start ; ; ) {
 146                 unsigned int newflags;
 147
 148                 /* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
 149
 150                 newflags = vma->vm_flags | VM_LOCKED;
 151                 if (!on)
 152                         newflags &= ~VM_LOCKED;
 153
 154                 if (vma->vm_end >= end) {
 155                         error = mlock_fixup(vma, nstart, end, newflags);
 156                         break;
 157                 }
 158
 159                 tmp = vma->vm_end;
 160                 next = vma->vm_next;
 161                 error = mlock_fixup(vma, nstart, tmp, newflags);
 162                 if (error)
 163                         break;
 164                 nstart = tmp;
 165                 vma = next;
 166                 if (!vma || vma->vm_start != nstart) {
 167                         error = -ENOMEM;
 168                         break;
 169                 }
 170         }
 171         merge_segments(current->mm, start, end);
 172         return error;
 173 }
 174
 175 asmlinkage int sys_mlock(unsigned long start, size_t len)
 176 {
 177         unsigned long locked;
 178         unsigned long lock_limit;
 179         int error = -ENOMEM;
 180
 181         down(&current->mm->mmap_sem);
 182         len = (len + (start & ~PAGE_MASK) + ~PAGE_MASK) & PAGE_MASK;
 183         start &= PAGE_MASK;
 184
 185         locked = len >> PAGE_SHIFT;
 186         locked += current->mm->locked_vm;
 187
 188         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 189         lock_limit >>= PAGE_SHIFT;
 190
 191         /* check against resource limits */
 192         if (locked > lock_limit)
 193                 goto out;
 194
 195         /* we may lock at most half of physical memory... */
 196         /* (this check is pretty bogus, but doesn't hurt) */
 197         if (locked > num_physpages/2)
 198                 goto out;
 199
 200         error = do_mlock(start, len, 1);
 201 out:
 202         up(&current->mm->mmap_sem);
 203         return error;
 204 }
 205
 206 asmlinkage int sys_munlock(unsigned long start, size_t len)
 207 {
 208         int ret;
 209
 210         down(&current->mm->mmap_sem);
 211         len = (len + (start & ~PAGE_MASK) + ~PAGE_MASK) & PAGE_MASK;
 212         start &= PAGE_MASK;
 213         ret = do_mlock(start, len, 0);
 214         up(&current->mm->mmap_sem);
 215         return ret;
 216 }
 217
 218 static int do_mlockall(int flags)
 219 {
 220         int error;
 221         unsigned int def_flags;
 222         struct vm_area_struct * vma;
 223
 224         if (!capable(CAP_IPC_LOCK))
 225                 return -EPERM;
 226
 227         def_flags = 0;
 228         if (flags & MCL_FUTURE)
 229                 def_flags = VM_LOCKED;
 230         current->mm->def_flags = def_flags;
 231
 232         error = 0;
 233         for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
 234                 unsigned int newflags;
 235
 236                 newflags = vma->vm_flags | VM_LOCKED;
 237                 if (!(flags & MCL_CURRENT))
 238                         newflags &= ~VM_LOCKED;
 239                 error = mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
 240                 if (error)
 241                         break;
 242         }
 243         merge_segments(current->mm, 0, TASK_SIZE);
 244         return error;
 245 }
 246
 247 asmlinkage int sys_mlockall(int flags)
 248 {
 249         unsigned long lock_limit;
 250         int ret = -EINVAL;
 251
 252         down(&current->mm->mmap_sem);
 253         if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
 254                 goto out;
 255
 256         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 257         lock_limit >>= PAGE_SHIFT;
 258
 259         ret = -ENOMEM;
 260         if (current->mm->total_vm > lock_limit)
 261                 goto out;
 262
 263         /* we may lock at most half of physical memory... */
 264         /* (this check is pretty bogus, but doesn't hurt) */
 265         if (current->mm->total_vm > num_physpages/2)
 266                 goto out;
 267
 268         ret = do_mlockall(flags);
 269 out:
 270         up(&current->mm->mmap_sem);
 271         return ret;
 272 }
 273
 274 asmlinkage int sys_munlockall(void)
 275 {
 276         int ret;
 277
 278         down(&current->mm->mmap_sem);
 279         ret = do_mlockall(0);
 280         up(&current->mm->mmap_sem);
 281         return ret;
 282 }