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/*
* linux/mm/mlock.c
*
* (C) Copyright 1995 Linus Torvalds
* (C) Copyright 2002 Christoph Hellwig
*/
#include <linux/mman.h>
#include <linux/mm.h>
static int mlock_fixup(struct vm_area_struct * vma,
unsigned long start, unsigned long end, unsigned int newflags)
{
struct mm_struct * mm = vma->vm_mm;
int pages;
int ret = 0;
if (newflags == vma->vm_flags)
goto out;
if (start != vma->vm_start) {
if (split_vma(mm, vma, start, 1)) {
ret = -EAGAIN;
goto out;
}
}
if (end != vma->vm_end) {
if (split_vma(mm, vma, end, 0)) {
ret = -EAGAIN;
goto out;
}
}
/*
* vm_flags is protected by the mmap_sem held in write mode.
* It's okay if try_to_unmap_one unmaps a page just after we
* set VM_LOCKED, make_pages_present below will bring it back.
*/
vma->vm_flags = newflags;
/*
* Keep track of amount of locked VM.
*/
pages = (end - start) >> PAGE_SHIFT;
if (newflags & VM_LOCKED) {
pages = -pages;
ret = make_pages_present(start, end);
}
vma->vm_mm->locked_vm -= pages;
out:
return ret;
}
static int do_mlock(unsigned long start, size_t len, int on)
{
unsigned long nstart, end, tmp;
struct vm_area_struct * vma, * next;
int error;
if (on && !capable(CAP_IPC_LOCK))
return -EPERM;
len = PAGE_ALIGN(len);
end = start + len;
if (end < start)
return -EINVAL;
if (end == start)
return 0;
vma = find_vma(current->mm, start);
if (!vma || vma->vm_start > start)
return -ENOMEM;
for (nstart = start ; ; ) {
unsigned int newflags;
/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
newflags = vma->vm_flags | VM_LOCKED;
if (!on)
newflags &= ~VM_LOCKED;
if (vma->vm_end >= end) {
error = mlock_fixup(vma, nstart, end, newflags);
break;
}
tmp = vma->vm_end;
next = vma->vm_next;
error = mlock_fixup(vma, nstart, tmp, newflags);
if (error)
break;
nstart = tmp;
vma = next;
if (!vma || vma->vm_start != nstart) {
error = -ENOMEM;
break;
}
}
return error;
}
asmlinkage long sys_mlock(unsigned long start, size_t len)
{
unsigned long locked;
unsigned long lock_limit;
int error = -ENOMEM;
down_write(¤t->mm->mmap_sem);
len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
start &= PAGE_MASK;
locked = len >> PAGE_SHIFT;
locked += current->mm->locked_vm;
lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
lock_limit >>= PAGE_SHIFT;
/* check against resource limits */
if (locked <= lock_limit)
error = do_mlock(start, len, 1);
up_write(¤t->mm->mmap_sem);
return error;
}
asmlinkage long sys_munlock(unsigned long start, size_t len)
{
int ret;
down_write(¤t->mm->mmap_sem);
len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
start &= PAGE_MASK;
ret = do_mlock(start, len, 0);
up_write(¤t->mm->mmap_sem);
return ret;
}
static int do_mlockall(int flags)
{
int error;
unsigned int def_flags;
struct vm_area_struct * vma;
if (!capable(CAP_IPC_LOCK))
return -EPERM;
def_flags = 0;
if (flags & MCL_FUTURE)
def_flags = VM_LOCKED;
current->mm->def_flags = def_flags;
error = 0;
for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
unsigned int newflags;
newflags = vma->vm_flags | VM_LOCKED;
if (!(flags & MCL_CURRENT))
newflags &= ~VM_LOCKED;
/* Ignore errors */
mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
}
return error;
}
asmlinkage long sys_mlockall(int flags)
{
unsigned long lock_limit;
int ret = -EINVAL;
down_write(¤t->mm->mmap_sem);
if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
goto out;
lock_limit = current->rlim[RLIMIT_MEMLOCK].rlim_cur;
lock_limit >>= PAGE_SHIFT;
ret = -ENOMEM;
if (current->mm->total_vm <= lock_limit)
ret = do_mlockall(flags);
out:
up_write(¤t->mm->mmap_sem);
return ret;
}
asmlinkage long sys_munlockall(void)
{
int ret;
down_write(¤t->mm->mmap_sem);
ret = do_mlockall(0);
up_write(¤t->mm->mmap_sem);
return ret;
}
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