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                 atomic_inc(&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                 atomic_inc(&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                 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         lock_kernel();
 183         len = (len + (start & ~PAGE_MASK) + ~PAGE_MASK) & PAGE_MASK;
 184         start &= PAGE_MASK;
 185
 186         locked = len >> PAGE_SHIFT;
 187         locked += current->mm->locked_vm;
 188
 189         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 190         lock_limit >>= PAGE_SHIFT;
 191
 192         /* check against resource limits */
 193         if (locked > lock_limit)
 194                 goto out;
 195
 196         /* we may lock at most half of physical memory... */
 197         /* (this check is pretty bogus, but doesn't hurt) */
 198         if (locked > num_physpages/2)
 199                 goto out;
 200
 201         error = do_mlock(start, len, 1);
 202 out:
 203         unlock_kernel();
 204         up(&current->mm->mmap_sem);
 205         return error;
 206 }
 207
 208 asmlinkage int sys_munlock(unsigned long start, size_t len)
 209 {
 210         int ret;
 211
 212         down(&current->mm->mmap_sem);
 213         lock_kernel();
 214         len = (len + (start & ~PAGE_MASK) + ~PAGE_MASK) & PAGE_MASK;
 215         start &= PAGE_MASK;
 216         ret = do_mlock(start, len, 0);
 217         unlock_kernel();
 218         up(&current->mm->mmap_sem);
 219         return ret;
 220 }
 221
 222 static int do_mlockall(int flags)
 223 {
 224         int error;
 225         unsigned int def_flags;
 226         struct vm_area_struct * vma;
 227
 228         if (!capable(CAP_IPC_LOCK))
 229                 return -EPERM;
 230
 231         def_flags = 0;
 232         if (flags & MCL_FUTURE)
 233                 def_flags = VM_LOCKED;
 234         current->mm->def_flags = def_flags;
 235
 236         error = 0;
 237         for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
 238                 unsigned int newflags;
 239
 240                 newflags = vma->vm_flags | VM_LOCKED;
 241                 if (!(flags & MCL_CURRENT))
 242                         newflags &= ~VM_LOCKED;
 243                 error = mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
 244                 if (error)
 245                         break;
 246         }
 247         merge_segments(current->mm, 0, TASK_SIZE);
 248         return error;
 249 }
 250
 251 asmlinkage int sys_mlockall(int flags)
 252 {
 253         unsigned long lock_limit;
 254         int ret = -EINVAL;
 255
 256         down(&current->mm->mmap_sem);
 257         lock_kernel();
 258         if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
 259                 goto out;
 260
 261         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 262         lock_limit >>= PAGE_SHIFT;
 263
 264         ret = -ENOMEM;
 265         if (current->mm->total_vm > lock_limit)
 266                 goto out;
 267
 268         /* we may lock at most half of physical memory... */
 269         /* (this check is pretty bogus, but doesn't hurt) */
 270         if (current->mm->total_vm > num_physpages/2)
 271                 goto out;
 272
 273         ret = do_mlockall(flags);
 274 out:
 275         unlock_kernel();
 276         up(&current->mm->mmap_sem);
 277         return ret;
 278 }
 279
 280 asmlinkage int sys_munlockall(void)
 281 {
 282         int ret;
 283
 284         down(&current->mm->mmap_sem);
 285         lock_kernel();
 286         ret = do_mlockall(0);
 287         unlock_kernel();
 288         up(&current->mm->mmap_sem);
 289         return ret;
 290 }