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         vx_vmlocked_sub(vma->vm_mm, pages);
  55 out:
  56         return ret;
  57 }
  58
  59 static int do_mlock(unsigned long start, size_t len, int on)
  60 {
  61         unsigned long nstart, end, tmp;
  62         struct vm_area_struct * vma, * next;
  63         int error;
  64
  65         if (on && !capable(CAP_IPC_LOCK))
  66                 return -EPERM;
  67         len = PAGE_ALIGN(len);
  68         end = start + len;
  69         if (end < start)
  70                 return -EINVAL;
  71         if (end == start)
  72                 return 0;
  73         vma = find_vma(current->mm, start);
  74         if (!vma || vma->vm_start > start)
  75                 return -ENOMEM;
  76
  77         for (nstart = start ; ; ) {
  78                 unsigned int newflags;
  79
  80                 /* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
  81
  82                 newflags = vma->vm_flags | VM_LOCKED;
  83                 if (!on)
  84                         newflags &= ~VM_LOCKED;
  85
  86                 if (vma->vm_end >= end) {
  87                         error = mlock_fixup(vma, nstart, end, newflags);
  88                         break;
  89                 }
  90
  91                 tmp = vma->vm_end;
  92                 next = vma->vm_next;
  93                 error = mlock_fixup(vma, nstart, tmp, newflags);
  94                 if (error)
  95                         break;
  96                 nstart = tmp;
  97                 vma = next;
  98                 if (!vma || vma->vm_start != nstart) {
  99                         error = -ENOMEM;
 100                         break;
 101                 }
 102         }
 103         return error;
 104 }
 105
 106 asmlinkage long sys_mlock(unsigned long start, size_t len)
 107 {
 108         unsigned long locked, grow;
 109         unsigned long lock_limit;
 110         int error = -ENOMEM;
 111
 112         down_write(&current->mm->mmap_sem);
 113         len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
 114         start &= PAGE_MASK;
 115
 116         grow = len >> PAGE_SHIFT;
 117         if (!vx_vmlocked_avail(current->mm, grow))
 118                 goto out;
 119         locked = current->mm->locked_vm + grow;
 120
 121         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 122         lock_limit >>= PAGE_SHIFT;
 123
 124         /* check against resource limits */
 125         if (locked <= lock_limit)
 126                 error = do_mlock(start, len, 1);
 127 out:
 128         up_write(&current->mm->mmap_sem);
 129         return error;
 130 }
 131
 132 asmlinkage long sys_munlock(unsigned long start, size_t len)
 133 {
 134         int ret;
 135
 136         down_write(&current->mm->mmap_sem);
 137         len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
 138         start &= PAGE_MASK;
 139         ret = do_mlock(start, len, 0);
 140         up_write(&current->mm->mmap_sem);
 141         return ret;
 142 }
 143
 144 static int do_mlockall(int flags)
 145 {
 146         int error;
 147         unsigned int def_flags;
 148         struct vm_area_struct * vma;
 149
 150         if (!capable(CAP_IPC_LOCK))
 151                 return -EPERM;
 152
 153         def_flags = 0;
 154         if (flags & MCL_FUTURE)
 155                 def_flags = VM_LOCKED;
 156         current->mm->def_flags = def_flags;
 157
 158         error = 0;
 159         for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
 160                 unsigned int newflags;
 161
 162                 newflags = vma->vm_flags | VM_LOCKED;
 163                 if (!(flags & MCL_CURRENT))
 164                         newflags &= ~VM_LOCKED;
 165
 166                 /* Ignore errors */
 167                 mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
 168         }
 169         return error;
 170 }
 171
 172 asmlinkage long sys_mlockall(int flags)
 173 {
 174         unsigned long lock_limit;
 175         int ret = -EINVAL;
 176
 177         down_write(&current->mm->mmap_sem);
 178         if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
 179                 goto out;
 180
 181         lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
 182         lock_limit >>= PAGE_SHIFT;
 183
 184         ret = -ENOMEM;
 185         if (!vx_vmlocked_avail(current->mm, current->mm->total_vm))
 186                 goto out;
 187         if (current->mm->total_vm <= lock_limit)
 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 }