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                 n->vm_file->f_count++;
  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                 n->vm_file->f_count++;
  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                 vma->vm_file->f_count += 2;
  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                 vma->vm_mm->locked_vm += pages;
 121                 make_pages_present(start, end);
 122         }
 123         return retval;
 124 }
 125
 126 static int do_mlock(unsigned long start, size_t len, int on)
 127 {
 128         unsigned long nstart, end, tmp;
 129         struct vm_area_struct * vma, * next;
 130         int error;
 131
 132         if (!capable(CAP_IPC_LOCK))
 133                 return -EPERM;
 134         len = (len + ~PAGE_MASK) & PAGE_MASK;
 135         end = start + len;
 136         if (end < start)
 137                 return -EINVAL;
 138         if (end == start)
 139                 return 0;
 140         vma = find_vma(current->mm, start);
 141         if (!vma || vma->vm_start > start)
 142                 return -ENOMEM;
 143
 144         for (nstart = start ; ; ) {
 145                 unsigned int newflags;
 146
 147                 /* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
 148
 149                 newflags = vma->vm_flags | VM_LOCKED;
 150                 if (!on)
 151                         newflags &= ~VM_LOCKED;
 152
 153                 if (vma->vm_end >= end) {
 154                         error = mlock_fixup(vma, nstart, end, newflags);
 155                         break;
 156                 }
 157
 158                 tmp = vma->vm_end;
 159                 next = vma->vm_next;
 160                 error = mlock_fixup(vma, nstart, tmp, newflags);
 161                 if (error)
 162                         break;
 163                 nstart = tmp;
 164                 vma = next;
 165                 if (!vma || vma->vm_start != nstart) {
 166                         error = -ENOMEM;
 167                         break;
 168                 }
 169         }
 170         merge_segments(current->mm, start, end);
 171         return error;
 172 }
 173
 174 asmlinkage int sys_mlock(unsigned long start, size_t len)
 175 {
 176         unsigned long locked;
 177         unsigned long lock_limit;
 178         int error = -ENOMEM;
 179
 180         down(&current->mm->mmap_sem);
 181         lock_kernel();
 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         unlock_kernel();
 203         up(&current->mm->mmap_sem);
 204         return error;
 205 }
 206
 207 asmlinkage int sys_munlock(unsigned long start, size_t len)
 208 {
 209         int ret;
 210
 211         down(&current->mm->mmap_sem);
 212         lock_kernel();
 213         len = (len + (start & ~PAGE_MASK) + ~PAGE_MASK) & PAGE_MASK;
 214         start &= PAGE_MASK;
 215         ret = do_mlock(start, len, 0);
 216         unlock_kernel();
 217         up(&current->mm->mmap_sem);
 218         return ret;
 219 }
 220
 221 static int do_mlockall(int flags)
 222 {
 223         int error;
 224         unsigned int def_flags;
 225         struct vm_area_struct * vma;
 226
 227         if (!capable(CAP_IPC_LOCK))
 228                 return -EPERM;
 229
 230         def_flags = 0;
 231         if (flags & MCL_FUTURE)
 232                 def_flags = VM_LOCKED;
 233         current->mm->def_flags = def_flags;
 234
 235         error = 0;
 236         for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
 237                 unsigned int newflags;
 238
 239                 newflags = vma->vm_flags | VM_LOCKED;
 240                 if (!(flags & MCL_CURRENT))
 241                         newflags &= ~VM_LOCKED;
 242                 error = mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
 243                 if (error)
 244                         break;
 245         }
 246         merge_segments(current->mm, 0, TASK_SIZE);
 247         return error;
 248 }
 249
 250 asmlinkage int sys_mlockall(int flags)
 251 {
 252         unsigned long lock_limit;
 253         int ret = -EINVAL;
 254
 255         down(&current->mm->mmap_sem);
 256         lock_kernel();
 257         if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
 258                 goto out;
 259
 260         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 261         lock_limit >>= PAGE_SHIFT;
 262
 263         ret = -ENOMEM;
 264         if (current->mm->total_vm > lock_limit)
 265                 goto out;
 266
 267         /* we may lock at most half of physical memory... */
 268         /* (this check is pretty bogus, but doesn't hurt) */
 269         if (current->mm->total_vm > num_physpages/2)
 270                 goto out;
 271
 272         ret = do_mlockall(flags);
 273 out:
 274         unlock_kernel();
 275         up(&current->mm->mmap_sem);
 276         return ret;
 277 }
 278
 279 asmlinkage int sys_munlockall(void)
 280 {
 281         int ret;
 282
 283         down(&current->mm->mmap_sem);
 284         lock_kernel();
 285         ret = do_mlockall(0);
 286         unlock_kernel();
 287         up(&current->mm->mmap_sem);
 288         return ret;
 289 }