mm/mlock.c

   1 /*
   2  *      linux/mm/mlock.c
   3  *
   4  *  (C) Copyright 1995 Linus Torvalds
   5  */
   6 #include <linux/stat.h>
   7 #include <linux/sched.h>
   8 #include <linux/kernel.h>
   9 #include <linux/mm.h>
  10 #include <linux/slab.h>
  11 #include <linux/shm.h>
  12 #include <linux/errno.h>
  13 #include <linux/mman.h>
  14 #include <linux/string.h>
  15 #include <linux/smp.h>
  16 #include <linux/smp_lock.h>
  17
  18 #include <asm/uaccess.h>
  19 #include <asm/system.h>
  20 #include <asm/pgtable.h>
  21
  22 static inline int mlock_fixup_all(struct vm_area_struct * vma, int newflags)
  23 {
  24         vma->vm_flags = newflags;
  25         return 0;
  26 }
  27
  28 static inline int mlock_fixup_start(struct vm_area_struct * vma,
  29         unsigned long end, int newflags)
  30 {
  31         struct vm_area_struct * n;
  32
  33         n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
  34         if (!n)
  35                 return -EAGAIN;
  36         *n = *vma;
  37         vma->vm_start = end;
  38         n->vm_end = end;
  39         vma->vm_offset += vma->vm_start - n->vm_start;
  40         n->vm_flags = newflags;
  41         if (n->vm_file)
  42                 n->vm_file->f_count++;
  43         if (n->vm_ops && n->vm_ops->open)
  44                 n->vm_ops->open(n);
  45         insert_vm_struct(current->mm, n);
  46         return 0;
  47 }
  48
  49 static inline int mlock_fixup_end(struct vm_area_struct * vma,
  50         unsigned long start, int newflags)
  51 {
  52         struct vm_area_struct * n;
  53
  54         n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
  55         if (!n)
  56                 return -EAGAIN;
  57         *n = *vma;
  58         vma->vm_end = start;
  59         n->vm_start = start;
  60         n->vm_offset += n->vm_start - vma->vm_start;
  61         n->vm_flags = newflags;
  62         if (n->vm_file)
  63                 n->vm_file->f_count++;
  64         if (n->vm_ops && n->vm_ops->open)
  65                 n->vm_ops->open(n);
  66         insert_vm_struct(current->mm, n);
  67         return 0;
  68 }
  69
  70 static inline int mlock_fixup_middle(struct vm_area_struct * vma,
  71         unsigned long start, unsigned long end, int newflags)
  72 {
  73         struct vm_area_struct * left, * right;
  74
  75         left = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
  76         if (!left)
  77                 return -EAGAIN;
  78         right = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
  79         if (!right) {
  80                 kmem_cache_free(vm_area_cachep, left);
  81                 return -EAGAIN;
  82         }
  83         *left = *vma;
  84         *right = *vma;
  85         left->vm_end = start;
  86         vma->vm_start = start;
  87         vma->vm_end = end;
  88         right->vm_start = end;
  89         vma->vm_offset += vma->vm_start - left->vm_start;
  90         right->vm_offset += right->vm_start - left->vm_start;
  91         vma->vm_flags = newflags;
  92         if (vma->vm_file)
  93                 vma->vm_file->f_count += 2;
  94
  95         if (vma->vm_ops && vma->vm_ops->open) {
  96                 vma->vm_ops->open(left);
  97                 vma->vm_ops->open(right);
  98         }
  99         insert_vm_struct(current->mm, left);
 100         insert_vm_struct(current->mm, right);
 101         return 0;
 102 }
 103
 104 static int mlock_fixup(struct vm_area_struct * vma,
 105         unsigned long start, unsigned long end, unsigned int newflags)
 106 {
 107         int pages, retval;
 108
 109         if (newflags == vma->vm_flags)
 110                 return 0;
 111
 112         if (start == vma->vm_start) {
 113                 if (end == vma->vm_end)
 114                         retval = mlock_fixup_all(vma, newflags);
 115                 else
 116                         retval = mlock_fixup_start(vma, end, newflags);
 117         } else {
 118                 if (end == vma->vm_end)
 119                         retval = mlock_fixup_end(vma, start, newflags);
 120                 else
 121                         retval = mlock_fixup_middle(vma, start, end, newflags);
 122         }
 123         if (!retval) {
 124                 /* keep track of amount of locked VM */
 125                 pages = (end - start) >> PAGE_SHIFT;
 126                 if (!(newflags & VM_LOCKED))
 127                         pages = -pages;
 128                 vma->vm_mm->locked_vm += pages;
 129
 130                 if (newflags & VM_LOCKED)
 131                         while (start < end) {
 132                                 char c;
 133                                 get_user(c,(char *) start);
 134                                 __asm__ __volatile__("": :"r" (c));
 135                                 start += PAGE_SIZE;
 136                         }
 137         }
 138         return retval;
 139 }
 140
 141 static int do_mlock(unsigned long start, size_t len, int on)
 142 {
 143         unsigned long nstart, end, tmp;
 144         struct vm_area_struct * vma, * next;
 145         int error;
 146
 147         if (!suser())
 148                 return -EPERM;
 149         len = (len + ~PAGE_MASK) & PAGE_MASK;
 150         end = start + len;
 151         if (end < start)
 152                 return -EINVAL;
 153         if (end == start)
 154                 return 0;
 155         vma = find_vma(current->mm, start);
 156         if (!vma || vma->vm_start > start)
 157                 return -ENOMEM;
 158
 159         for (nstart = start ; ; ) {
 160                 unsigned int newflags;
 161
 162                 /* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
 163
 164                 newflags = vma->vm_flags | VM_LOCKED;
 165                 if (!on)
 166                         newflags &= ~VM_LOCKED;
 167
 168                 if (vma->vm_end >= end) {
 169                         error = mlock_fixup(vma, nstart, end, newflags);
 170                         break;
 171                 }
 172
 173                 tmp = vma->vm_end;
 174                 next = vma->vm_next;
 175                 error = mlock_fixup(vma, nstart, tmp, newflags);
 176                 if (error)
 177                         break;
 178                 nstart = tmp;
 179                 vma = next;
 180                 if (!vma || vma->vm_start != nstart) {
 181                         error = -ENOMEM;
 182                         break;
 183                 }
 184         }
 185         merge_segments(current->mm, start, end);
 186         return error;
 187 }
 188
 189 asmlinkage int sys_mlock(unsigned long start, size_t len)
 190 {
 191         unsigned long locked;
 192         unsigned long lock_limit;
 193         int error = -ENOMEM;
 194
 195         lock_kernel();
 196         len = (len + (start & ~PAGE_MASK) + ~PAGE_MASK) & PAGE_MASK;
 197         start &= PAGE_MASK;
 198
 199         locked = len >> PAGE_SHIFT;
 200         locked += current->mm->locked_vm;
 201
 202         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 203         lock_limit >>= PAGE_SHIFT;
 204
 205         /* check against resource limits */
 206         if (locked > lock_limit)
 207                 goto out;
 208
 209         /* we may lock at most half of physical memory... */
 210         /* (this check is pretty bogus, but doesn't hurt) */
 211         if (locked > num_physpages/2)
 212                 goto out;
 213
 214         error = do_mlock(start, len, 1);
 215 out:
 216         unlock_kernel();
 217         return error;
 218 }
 219
 220 asmlinkage int sys_munlock(unsigned long start, size_t len)
 221 {
 222         int ret;
 223
 224         lock_kernel();
 225         len = (len + (start & ~PAGE_MASK) + ~PAGE_MASK) & PAGE_MASK;
 226         start &= PAGE_MASK;
 227         ret = do_mlock(start, len, 0);
 228         unlock_kernel();
 229         return ret;
 230 }
 231
 232 static int do_mlockall(int flags)
 233 {
 234         int error;
 235         unsigned int def_flags;
 236         struct vm_area_struct * vma;
 237
 238         if (!suser())
 239                 return -EPERM;
 240
 241         def_flags = 0;
 242         if (flags & MCL_FUTURE)
 243                 def_flags = VM_LOCKED;
 244         current->mm->def_flags = def_flags;
 245
 246         error = 0;
 247         for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
 248                 unsigned int newflags;
 249
 250                 newflags = vma->vm_flags | VM_LOCKED;
 251                 if (!(flags & MCL_CURRENT))
 252                         newflags &= ~VM_LOCKED;
 253                 error = mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
 254                 if (error)
 255                         break;
 256         }
 257         merge_segments(current->mm, 0, TASK_SIZE);
 258         return error;
 259 }
 260
 261 asmlinkage int sys_mlockall(int flags)
 262 {
 263         unsigned long lock_limit;
 264         int ret = -EINVAL;
 265
 266         lock_kernel();
 267         if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
 268                 goto out;
 269
 270         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 271         lock_limit >>= PAGE_SHIFT;
 272
 273         ret = -ENOMEM;
 274         if (current->mm->total_vm > lock_limit)
 275                 goto out;
 276
 277         /* we may lock at most half of physical memory... */
 278         /* (this check is pretty bogus, but doesn't hurt) */
 279         if (current->mm->total_vm > num_physpages/2)
 280                 goto out;
 281
 282         ret = do_mlockall(flags);
 283 out:
 284         unlock_kernel();
 285         return ret;
 286 }
 287
 288 asmlinkage int sys_munlockall(void)
 289 {
 290         int ret;
 291
 292         lock_kernel();
 293         ret = do_mlockall(0);
 294         unlock_kernel();
 295         return ret;
 296 }