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 #include <linux/vs_memory.h>
  11
  12
  13 static int mlock_fixup(struct vm_area_struct * vma,
  14         unsigned long start, unsigned long end, unsigned int newflags)
  15 {
  16         struct mm_struct * mm = vma->vm_mm;
  17         int pages;
  18         int ret = 0;
  19
  20         if (newflags == vma->vm_flags)
  21                 goto out;
  22
  23         if (start != vma->vm_start) {
  24                 if (split_vma(mm, vma, start, 1)) {
  25                         ret = -EAGAIN;
  26                         goto out;
  27                 }
  28         }
  29
  30         if (end != vma->vm_end) {
  31                 if (split_vma(mm, vma, end, 0)) {
  32                         ret = -EAGAIN;
  33                         goto out;
  34                 }
  35         }
  36
  37         /*
  38          * vm_flags is protected by the mmap_sem held in write mode.
  39          * It's okay if try_to_unmap_one unmaps a page just after we
  40          * set VM_LOCKED, make_pages_present below will bring it back.
  41          */
  42         vma->vm_flags = newflags;
  43
  44         /*
  45          * Keep track of amount of locked VM.
  46          */
  47         pages = (end - start) >> PAGE_SHIFT;
  48         if (newflags & VM_LOCKED) {
  49                 pages = -pages;
  50                 ret = make_pages_present(start, end);
  51         }
  52
  53         vma->vm_mm->locked_vm -= pages;
  54 out:
  55         return ret;
  56 }
  57
  58 static int do_mlock(unsigned long start, size_t len, int on)
  59 {
  60         unsigned long nstart, end, tmp;
  61         struct vm_area_struct * vma, * next;
  62         int error;
  63
  64         if (on && !capable(CAP_IPC_LOCK))
  65                 return -EPERM;
  66         len = PAGE_ALIGN(len);
  67         end = start + len;
  68         if (end < start)
  69                 return -EINVAL;
  70         if (end == start)
  71                 return 0;
  72         vma = find_vma(current->mm, start);
  73         if (!vma || vma->vm_start > start)
  74                 return -ENOMEM;
  75
  76         for (nstart = start ; ; ) {
  77                 unsigned int newflags;
  78
  79                 /* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
  80
  81                 newflags = vma->vm_flags | VM_LOCKED;
  82                 if (!on)
  83                         newflags &= ~VM_LOCKED;
  84
  85                 if (vma->vm_end >= end) {
  86                         error = mlock_fixup(vma, nstart, end, newflags);
  87                         break;
  88                 }
  89
  90                 tmp = vma->vm_end;
  91                 next = vma->vm_next;
  92                 error = mlock_fixup(vma, nstart, tmp, newflags);
  93                 if (error)
  94                         break;
  95                 nstart = tmp;
  96                 vma = next;
  97                 if (!vma || vma->vm_start != nstart) {
  98                         error = -ENOMEM;
  99                         break;
 100                 }
 101         }
 102         return error;
 103 }
 104
 105 asmlinkage long sys_mlock(unsigned long start, size_t len)
 106 {
 107         unsigned long locked, grow;
 108         unsigned long lock_limit;
 109         int error = -ENOMEM;
 110
 111         down_write(&current->mm->mmap_sem);
 112         len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
 113         start &= PAGE_MASK;
 114
 115         grow = len >> PAGE_SHIFT;
 116         if (!vx_vmlocked_avail(current->mm, grow))
 117                 goto out;
 118         locked = current->mm->locked_vm + grow;
 119
 120         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 121         lock_limit >>= PAGE_SHIFT;
 122
 123         /* check against resource limits */
 124         if (locked <= lock_limit)
 125                 error = do_mlock(start, len, 1);
 126 out:
 127         up_write(&current->mm->mmap_sem);
 128         return error;
 129 }
 130
 131 asmlinkage long sys_munlock(unsigned long start, size_t len)
 132 {
 133         int ret;
 134
 135         down_write(&current->mm->mmap_sem);
 136         len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
 137         start &= PAGE_MASK;
 138         ret = do_mlock(start, len, 0);
 139         up_write(&current->mm->mmap_sem);
 140         return ret;
 141 }
 142
 143 static int do_mlockall(int flags)
 144 {
 145         int error;
 146         unsigned int def_flags;
 147         struct vm_area_struct * vma;
 148
 149         if (!capable(CAP_IPC_LOCK))
 150                 return -EPERM;
 151
 152         def_flags = 0;
 153         if (flags & MCL_FUTURE)
 154                 def_flags = VM_LOCKED;
 155         current->mm->def_flags = def_flags;
 156
 157         error = 0;
 158         for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
 159                 unsigned int newflags;
 160
 161                 newflags = vma->vm_flags | VM_LOCKED;
 162                 if (!(flags & MCL_CURRENT))
 163                         newflags &= ~VM_LOCKED;
 164
 165                 /* Ignore errors */
 166                 mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
 167         }
 168         return error;
 169 }
 170
 171 asmlinkage long sys_mlockall(int flags)
 172 {
 173         unsigned long lock_limit;
 174         int ret = -EINVAL;
 175
 176         down_write(&current->mm->mmap_sem);
 177         if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
 178                 goto out;
 179
 180         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 181         lock_limit >>= PAGE_SHIFT;
 182
 183         ret = -ENOMEM;
 184         if (!vx_vmlocked_avail(current->mm, current->mm->total_vm))
 185                 goto out;
 186         /* check vserver lock limits? */
 187         if ((current->mm->total_vm <= lock_limit) || capable(CAP_IPC_LOCK))
 188                 ret = do_mlockall(flags);
 189 out:
 190         up_write(&current->mm->mmap_sem);
 191         return ret;
 192 }
 193
 194 asmlinkage long sys_munlockall(void)
 195 {
 196         int ret;
 197
 198         down_write(&current->mm->mmap_sem);
 199         ret = do_mlockall(0);
 200         up_write(&current->mm->mmap_sem);
 201         return ret;
 202 }