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/*

 *      linux/mm/mlock.c

 *

 *  (C) Copyright 1995 Linus Torvalds

 */

#include <linux/slab.h>

#include <linux/shm.h>

#include <linux/mman.h>

#include <linux/smp_lock.h>

#include <linux/pagemap.h>

#include <asm/uaccess.h>

#include <asm/pgtable.h>

static inline int mlock_fixup_all(struct vm_area_struct * vma, int newflags)

{

        spin_lock(&vma->vm_mm->page_table_lock);

        vma->vm_flags = newflags;

        spin_unlock(&vma->vm_mm->page_table_lock);

        return 0;

}

static inline int mlock_fixup_start(struct vm_area_struct * vma,

        unsigned long end, int newflags)

{

        struct vm_area_struct * n;

        n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);

        if (!n)

                return -EAGAIN;

        *n = *vma;

        n->vm_end = end;

        n->vm_flags = newflags;

        n->vm_raend = 0;

        if (n->vm_file)

                get_file(n->vm_file);

        if (n->vm_ops && n->vm_ops->open)

                n->vm_ops->open(n);

        vma->vm_pgoff += (end - vma->vm_start) >> PAGE_SHIFT;

        lock_vma_mappings(vma);

        spin_lock(&vma->vm_mm->page_table_lock);

        vma->vm_start = end;

        __insert_vm_struct(current->mm, n);

        spin_unlock(&vma->vm_mm->page_table_lock);

        unlock_vma_mappings(vma);

        return 0;

}

static inline int mlock_fixup_end(struct vm_area_struct * vma,

        unsigned long start, int newflags)

{

        struct vm_area_struct * n;

        n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);

        if (!n)

                return -EAGAIN;

        *n = *vma;

        n->vm_start = start;

        n->vm_pgoff += (n->vm_start - vma->vm_start) >> PAGE_SHIFT;

        n->vm_flags = newflags;

        n->vm_raend = 0;

        if (n->vm_file)

                get_file(n->vm_file);

        if (n->vm_ops && n->vm_ops->open)

                n->vm_ops->open(n);

        lock_vma_mappings(vma);

        spin_lock(&vma->vm_mm->page_table_lock);

        vma->vm_end = start;

        __insert_vm_struct(current->mm, n);

        spin_unlock(&vma->vm_mm->page_table_lock);

        unlock_vma_mappings(vma);

        return 0;

}

static inline int mlock_fixup_middle(struct vm_area_struct * vma,

        unsigned long start, unsigned long end, int newflags)

{

        struct vm_area_struct * left, * right;

        left = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);

        if (!left)

                return -EAGAIN;

        right = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);

        if (!right) {

                kmem_cache_free(vm_area_cachep, left);

                return -EAGAIN;

        }

        *left = *vma;

        *right = *vma;

        left->vm_end = start;

        right->vm_start = end;

        right->vm_pgoff += (right->vm_start - left->vm_start) >> PAGE_SHIFT;

        vma->vm_flags = newflags;

        left->vm_raend = 0;

        right->vm_raend = 0;

        if (vma->vm_file)

                atomic_add(2, &vma->vm_file->f_count);

        if (vma->vm_ops && vma->vm_ops->open) {

                vma->vm_ops->open(left);

                vma->vm_ops->open(right);

        }

        vma->vm_raend = 0;

        vma->vm_pgoff += (start - vma->vm_start) >> PAGE_SHIFT;

        lock_vma_mappings(vma);

        spin_lock(&vma->vm_mm->page_table_lock);

        vma->vm_start = start;

        vma->vm_end = end;

        vma->vm_flags = newflags;

        __insert_vm_struct(current->mm, left);

        __insert_vm_struct(current->mm, right);

        spin_unlock(&vma->vm_mm->page_table_lock);

        unlock_vma_mappings(vma);

        return 0;

}

static int mlock_fixup(struct vm_area_struct * vma,

        unsigned long start, unsigned long end, unsigned int newflags)

{

        int pages, retval;

        if (newflags == vma->vm_flags)

                return 0;

        if (start == vma->vm_start) {

                if (end == vma->vm_end)

                        retval = mlock_fixup_all(vma, newflags);

                else

                        retval = mlock_fixup_start(vma, end, newflags);

        } else {

                if (end == vma->vm_end)

                        retval = mlock_fixup_end(vma, start, newflags);

                else

                        retval = mlock_fixup_middle(vma, start, end, newflags);

        }

        if (!retval) {

                /* keep track of amount of locked VM */

                pages = (end - start) >> PAGE_SHIFT;

                if (newflags & VM_LOCKED) {

                        pages = -pages;

                        make_pages_present(start, end);

                }

                vma->vm_mm->locked_vm -= pages;

        }

        return retval;

}

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(&current->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)

                goto out;

        /* we may lock at most half of physical memory... */

        /* (this check is pretty bogus, but doesn't hurt) */

        if (locked > num_physpages/2)

                goto out;

        error = do_mlock(start, len, 1);

out:

        up_write(&current->mm->mmap_sem);

        return error;

}

asmlinkage long sys_munlock(unsigned long start, size_t len)

{

        int ret;

        down_write(&current->mm->mmap_sem);

        len = PAGE_ALIGN(len + (start & ~PAGE_MASK));

        start &= PAGE_MASK;

        ret = do_mlock(start, len, 0);

        up_write(&current->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;

                error = mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);

                if (error)

                        break;

        }

        return error;

}

asmlinkage long sys_mlockall(int flags)

{

        unsigned long lock_limit;

        int ret = -EINVAL;

        down_write(&current->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)

                goto out;

        /* we may lock at most half of physical memory... */

        /* (this check is pretty bogus, but doesn't hurt) */

        if (current->mm->total_vm > num_physpages/2)

                goto out;

        ret = do_mlockall(flags);

out:

        up_write(&current->mm->mmap_sem);

        return ret;

}

asmlinkage long sys_munlockall(void)

{

        int ret;

        down_write(&current->mm->mmap_sem);

        ret = do_mlockall(0);

        up_write(&current->mm->mmap_sem);

        return ret;

}