diff options
Diffstat (limited to 'mm/mlock.c')
| -rw-r--r-- | mm/mlock.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/mm/mlock.c b/mm/mlock.c new file mode 100644 index 000000000000..4ae3a46ff768 --- /dev/null +++ b/mm/mlock.c @@ -0,0 +1,253 @@ +/* + * linux/mm/mlock.c + * + * (C) Copyright 1995 Linus Torvalds + * (C) Copyright 2002 Christoph Hellwig + */ + +#include <linux/mman.h> +#include <linux/mm.h> +#include <linux/mempolicy.h> +#include <linux/syscalls.h> + + +static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev, + unsigned long start, unsigned long end, unsigned int newflags) +{ + struct mm_struct * mm = vma->vm_mm; + pgoff_t pgoff; + int pages; + int ret = 0; + + if (newflags == vma->vm_flags) { + *prev = vma; + goto out; + } + + pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); + *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma, + vma->vm_file, pgoff, vma_policy(vma)); + if (*prev) { + vma = *prev; + goto success; + } + + *prev = vma; + + if (start != vma->vm_start) { + ret = split_vma(mm, vma, start, 1); + if (ret) + goto out; + } + + if (end != vma->vm_end) { + ret = split_vma(mm, vma, end, 0); + if (ret) + goto out; + } + +success: + /* + * 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; + if (!(newflags & VM_IO)) + ret = make_pages_present(start, end); + } + + vma->vm_mm->locked_vm -= pages; +out: + if (ret == -ENOMEM) + ret = -EAGAIN; + return ret; +} + +static int do_mlock(unsigned long start, size_t len, int on) +{ + unsigned long nstart, end, tmp; + struct vm_area_struct * vma, * prev; + int error; + + len = PAGE_ALIGN(len); + end = start + len; + if (end < start) + return -EINVAL; + if (end == start) + return 0; + vma = find_vma_prev(current->mm, start, &prev); + if (!vma || vma->vm_start > start) + return -ENOMEM; + + if (start > vma->vm_start) + prev = vma; + + 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; + + tmp = vma->vm_end; + if (tmp > end) + tmp = end; + error = mlock_fixup(vma, &prev, nstart, tmp, newflags); + if (error) + break; + nstart = tmp; + if (nstart < prev->vm_end) + nstart = prev->vm_end; + if (nstart >= end) + break; + + vma = prev->vm_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; + + if (!can_do_mlock()) + return -EPERM; + + 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->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; + lock_limit >>= PAGE_SHIFT; + + /* check against resource limits */ + if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) + 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) +{ + struct vm_area_struct * vma, * prev = NULL; + unsigned int def_flags = 0; + + if (flags & MCL_FUTURE) + def_flags = VM_LOCKED; + current->mm->def_flags = def_flags; + if (flags == MCL_FUTURE) + goto out; + + for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { + unsigned int newflags; + + newflags = vma->vm_flags | VM_LOCKED; + if (!(flags & MCL_CURRENT)) + newflags &= ~VM_LOCKED; + + /* Ignore errors */ + mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); + } +out: + return 0; +} + +asmlinkage long sys_mlockall(int flags) +{ + unsigned long lock_limit; + int ret = -EINVAL; + + if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE))) + goto out; + + ret = -EPERM; + if (!can_do_mlock()) + goto out; + + down_write(¤t->mm->mmap_sem); + + lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; + lock_limit >>= PAGE_SHIFT; + + ret = -ENOMEM; + if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || + capable(CAP_IPC_LOCK)) + ret = do_mlockall(flags); + up_write(¤t->mm->mmap_sem); +out: + 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; +} + +/* + * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB + * shm segments) get accounted against the user_struct instead. + */ +static DEFINE_SPINLOCK(shmlock_user_lock); + +int user_shm_lock(size_t size, struct user_struct *user) +{ + unsigned long lock_limit, locked; + int allowed = 0; + + locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; + lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; + lock_limit >>= PAGE_SHIFT; + spin_lock(&shmlock_user_lock); + if (locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK)) + goto out; + get_uid(user); + user->locked_shm += locked; + allowed = 1; +out: + spin_unlock(&shmlock_user_lock); + return allowed; +} + +void user_shm_unlock(size_t size, struct user_struct *user) +{ + spin_lock(&shmlock_user_lock); + user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT; + spin_unlock(&shmlock_user_lock); + free_uid(user); +} |
