/*
 *      linux/mm/mlock.c
 *
 *  (C) Copyright 1995 Linus Torvalds
 */
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/shm.h>
#include <linux/errno.h>
#include <linux/mman.h>
#include <linux/string.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/pgtable.h>

static inline int mlock_fixup_all(struct vm_area_struct * vma, int newflags)
{
        vma->vm_flags = newflags;
        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;
        vma->vm_start = end;
        n->vm_end = end;
        vma->vm_offset += vma->vm_start - n->vm_start;
        n->vm_flags = newflags;
        n->vm_dentry = dget(vma->vm_dentry);
        if (n->vm_ops && n->vm_ops->open)
                n->vm_ops->open(n);
        insert_vm_struct(current->mm, n);
        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;
        vma->vm_end = start;
        n->vm_start = start;
        n->vm_offset += n->vm_start - vma->vm_start;
        n->vm_flags = newflags;
        n->vm_dentry = dget(vma->vm_dentry);
        if (n->vm_ops && n->vm_ops->open)
                n->vm_ops->open(n);
        insert_vm_struct(current->mm, n);
        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;
        vma->vm_start = start;
        vma->vm_end = end;
        right->vm_start = end;
        vma->vm_offset += vma->vm_start - left->vm_start;
        right->vm_offset += right->vm_start - left->vm_start;
        vma->vm_flags = newflags;
        if (vma->vm_dentry)
                vma->vm_dentry->d_count += 2;

        if (vma->vm_ops && vma->vm_ops->open) {
                vma->vm_ops->open(left);
                vma->vm_ops->open(right);
        }
        insert_vm_struct(current->mm, left);
        insert_vm_struct(current->mm, right);
        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;
                vma->vm_mm->locked_vm += pages;

                if (newflags & VM_LOCKED)
                        while (start < end) {
                                char c;
                                get_user(c,(char *) start);
                                __asm__ __volatile__("": :"r" (c));
                                start += PAGE_SIZE;
                        }
        }
        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 (!suser())
                return -EPERM;
        len = (len + ~PAGE_MASK) & PAGE_MASK;
        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;
                }
        }
        merge_segments(current->mm, start, end);
        return error;
}

asmlinkage int sys_mlock(unsigned long start, size_t len)
{
        unsigned long locked;
        unsigned long lock_limit;
        int error = -ENOMEM;

        lock_kernel();
        len = (len + (start & ~PAGE_MASK) + ~PAGE_MASK) & 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:
        unlock_kernel();
        return error;
}

asmlinkage int sys_munlock(unsigned long start, size_t len)
{
        int ret;

        lock_kernel();
        len = (len + (start & ~PAGE_MASK) + ~PAGE_MASK) & PAGE_MASK;
        start &= PAGE_MASK;
        ret = do_mlock(start, len, 0);
        unlock_kernel();
        return ret;
}

static int do_mlockall(int flags)
{
        int error;
        unsigned int def_flags;
        struct vm_area_struct * vma;

        if (!suser())
                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;
        }
        merge_segments(current->mm, 0, TASK_SIZE);
        return error;
}

asmlinkage int sys_mlockall(int flags)
{
        unsigned long lock_limit;
        int ret = -EINVAL;

        lock_kernel();
        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:
        unlock_kernel();
        return ret;
}

asmlinkage int sys_munlockall(void)
{
        int ret;

        lock_kernel();
        ret = do_mlockall(0);
        unlock_kernel();
        return ret;
}