Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 *      mm/mremap.c

 *

 *      (C) Copyright 1996 Linus Torvalds

 *

 *      Address space accounting code   <alan@redhat.com>

 *      (C) Copyright 2002 Red Hat Inc, All Rights Reserved

 */

#include <linux/mm.h>

#include <linux/hugetlb.h>

#include <linux/slab.h>

#include <linux/shm.h>

#include <linux/mman.h>

#include <linux/swap.h>

#include <linux/capability.h>

#include <linux/fs.h>

#include <linux/highmem.h>

#include <linux/security.h>

#include <linux/syscalls.h>

#include <asm/uaccess.h>

#include <asm/cacheflush.h>

#include <asm/tlbflush.h>

static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)

{

        pgd_t *pgd;

        pud_t *pud;

        pmd_t *pmd;

        pgd = pgd_offset(mm, addr);

        if (pgd_none_or_clear_bad(pgd))

                return NULL;

        pud = pud_offset(pgd, addr);

        if (pud_none_or_clear_bad(pud))

                return NULL;

        pmd = pmd_offset(pud, addr);

        if (pmd_none_or_clear_bad(pmd))

                return NULL;

        return pmd;

}

static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)

{

        pgd_t *pgd;

        pud_t *pud;

        pmd_t *pmd;

        pgd = pgd_offset(mm, addr);

        pud = pud_alloc(mm, pgd, addr);

        if (!pud)

                return NULL;

        pmd = pmd_alloc(mm, pud, addr);

        if (!pmd)

                return NULL;

        if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))

                return NULL;

        return pmd;

}

static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,

                unsigned long old_addr, unsigned long old_end,

                struct vm_area_struct *new_vma, pmd_t *new_pmd,

                unsigned long new_addr)

{

        struct address_space *mapping = NULL;

        struct mm_struct *mm = vma->vm_mm;

        pte_t *old_pte, *new_pte, pte;

        spinlock_t *old_ptl, *new_ptl;

        if (vma->vm_file) {

                /*

                 * Subtle point from Rajesh Venkatasubramanian: before

                 * moving file-based ptes, we must lock vmtruncate out,

                 * since it might clean the dst vma before the src vma,

                 * and we propagate stale pages into the dst afterward.

                 */

                mapping = vma->vm_file->f_mapping;

                spin_lock(&mapping->i_mmap_lock);

                if (new_vma->vm_truncate_count &&

                    new_vma->vm_truncate_count != vma->vm_truncate_count)

                        new_vma->vm_truncate_count = 0;

        }

        /*

         * We don't have to worry about the ordering of src and dst

         * pte locks because exclusive mmap_sem prevents deadlock.

         */

        old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);

        new_pte = pte_offset_map_nested(new_pmd, new_addr);

        new_ptl = pte_lockptr(mm, new_pmd);

        if (new_ptl != old_ptl)

                spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);

        arch_enter_lazy_mmu_mode();

        for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,

                                   new_pte++, new_addr += PAGE_SIZE) {

                if (pte_none(*old_pte))

                        continue;

                pte = ptep_clear_flush(vma, old_addr, old_pte);

                pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);

                set_pte_at(mm, new_addr, new_pte, pte);

        }

        arch_leave_lazy_mmu_mode();

        if (new_ptl != old_ptl)

                spin_unlock(new_ptl);

        pte_unmap_nested(new_pte - 1);

        pte_unmap_unlock(old_pte - 1, old_ptl);

        if (mapping)

                spin_unlock(&mapping->i_mmap_lock);

}

#define LATENCY_LIMIT   (64 * PAGE_SIZE)

unsigned long move_page_tables(struct vm_area_struct *vma,

                unsigned long old_addr, struct vm_area_struct *new_vma,

                unsigned long new_addr, unsigned long len)

{

        unsigned long extent, next, old_end;

        pmd_t *old_pmd, *new_pmd;

        old_end = old_addr + len;

        flush_cache_range(vma, old_addr, old_end);

        for (; old_addr < old_end; old_addr += extent, new_addr += extent) {

                cond_resched();

                next = (old_addr + PMD_SIZE) & PMD_MASK;

                if (next - 1 > old_end)

                        next = old_end;

                extent = next - old_addr;

                old_pmd = get_old_pmd(vma->vm_mm, old_addr);

                if (!old_pmd)

                        continue;

                new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);

                if (!new_pmd)

                        break;

                next = (new_addr + PMD_SIZE) & PMD_MASK;

                if (extent > next - new_addr)

                        extent = next - new_addr;

                if (extent > LATENCY_LIMIT)

                        extent = LATENCY_LIMIT;

                move_ptes(vma, old_pmd, old_addr, old_addr + extent,

                                new_vma, new_pmd, new_addr);

        }

        return len + old_addr - old_end;        /* how much done */

}

static unsigned long move_vma(struct vm_area_struct *vma,

                unsigned long old_addr, unsigned long old_len,

                unsigned long new_len, unsigned long new_addr)

{

        struct mm_struct *mm = vma->vm_mm;

        struct vm_area_struct *new_vma;

        unsigned long vm_flags = vma->vm_flags;

        unsigned long new_pgoff;

        unsigned long moved_len;

        unsigned long excess = 0;

        unsigned long hiwater_vm;

        int split = 0;

        /*

         * We'd prefer to avoid failure later on in do_munmap:

         * which may split one vma into three before unmapping.

         */

        if (mm->map_count >= sysctl_max_map_count - 3)

                return -ENOMEM;

        new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);

        new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);

        if (!new_vma)

                return -ENOMEM;

        moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);

        if (moved_len < old_len) {

                /*

                 * On error, move entries back from new area to old,

                 * which will succeed since page tables still there,

                 * and then proceed to unmap new area instead of old.

                 */

                move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);

                vma = new_vma;

                old_len = new_len;

                old_addr = new_addr;

                new_addr = -ENOMEM;

        }

        /* Conceal VM_ACCOUNT so old reservation is not undone */

        if (vm_flags & VM_ACCOUNT) {

                vma->vm_flags &= ~VM_ACCOUNT;

                excess = vma->vm_end - vma->vm_start - old_len;

                if (old_addr > vma->vm_start &&

                    old_addr + old_len < vma->vm_end)

                        split = 1;

        }

        /*

         * If we failed to move page tables we still do total_vm increment

         * since do_munmap() will decrement it by old_len == new_len.

         *

         * Since total_vm is about to be raised artificially high for a

         * moment, we need to restore high watermark afterwards: if stats

         * are taken meanwhile, total_vm and hiwater_vm appear too high.

         * If this were a serious issue, we'd add a flag to do_munmap().

         */

        hiwater_vm = mm->hiwater_vm;

        mm->total_vm += new_len >> PAGE_SHIFT;

        vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);

        if (do_munmap(mm, old_addr, old_len) < 0) {

                /* OOM: unable to split vma, just get accounts right */

                vm_unacct_memory(excess >> PAGE_SHIFT);

                excess = 0;

        }

        mm->hiwater_vm = hiwater_vm;

        /* Restore VM_ACCOUNT if one or two pieces of vma left */

        if (excess) {

                vma->vm_flags |= VM_ACCOUNT;

                if (split)

                        vma->vm_next->vm_flags |= VM_ACCOUNT;

        }

        if (vm_flags & VM_LOCKED) {

                mm->locked_vm += new_len >> PAGE_SHIFT;

                if (new_len > old_len)

                        make_pages_present(new_addr + old_len,

                                           new_addr + new_len);

        }

        return new_addr;

}

/*

 * Expand (or shrink) an existing mapping, potentially moving it at the

 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)

 *

 * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise

 * This option implies MREMAP_MAYMOVE.

 */

unsigned long do_mremap(unsigned long addr,

        unsigned long old_len, unsigned long new_len,

        unsigned long flags, unsigned long new_addr)

{

        struct mm_struct *mm = current->mm;

        struct vm_area_struct *vma;

        unsigned long ret = -EINVAL;

        unsigned long charged = 0;

        if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))

                goto out;

        if (addr & ~PAGE_MASK)

                goto out;

        old_len = PAGE_ALIGN(old_len);

        new_len = PAGE_ALIGN(new_len);

        /*

         * We allow a zero old-len as a special case

         * for DOS-emu "duplicate shm area" thing. But

         * a zero new-len is nonsensical.

         */

        if (!new_len)

                goto out;

        /* new_addr is only valid if MREMAP_FIXED is specified */

        if (flags & MREMAP_FIXED) {

                if (new_addr & ~PAGE_MASK)

                        goto out;

                if (!(flags & MREMAP_MAYMOVE))

                        goto out;

                if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)

                        goto out;

                /* Check if the location we're moving into overlaps the

                 * old location at all, and fail if it does.

                 */

                if ((new_addr <= addr) && (new_addr+new_len) > addr)

                        goto out;

                if ((addr <= new_addr) && (addr+old_len) > new_addr)

                        goto out;

                ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);

                if (ret)

                        goto out;

                ret = do_munmap(mm, new_addr, new_len);

                if (ret)

                        goto out;

        }

        /*

         * Always allow a shrinking remap: that just unmaps

         * the unnecessary pages..

         * do_munmap does all the needed commit accounting

         */

        if (old_len >= new_len) {

                ret = do_munmap(mm, addr+new_len, old_len - new_len);

                if (ret && old_len != new_len)

                        goto out;

                ret = addr;

                if (!(flags & MREMAP_FIXED) || (new_addr == addr))

                        goto out;

                old_len = new_len;

        }

        /*

         * Ok, we need to grow..  or relocate.

         */

        ret = -EFAULT;

        vma = find_vma(mm, addr);

        if (!vma || vma->vm_start > addr)

                goto out;

        if (is_vm_hugetlb_page(vma)) {

                ret = -EINVAL;

                goto out;

        }

        /* We can't remap across vm area boundaries */

        if (old_len > vma->vm_end - addr)

                goto out;

        if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {

                if (new_len > old_len)

                        goto out;

        }

        if (vma->vm_flags & VM_LOCKED) {

                unsigned long locked, lock_limit;

                locked = mm->locked_vm << PAGE_SHIFT;

                lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;

                locked += new_len - old_len;

                ret = -EAGAIN;

                if (locked > lock_limit && !capable(CAP_IPC_LOCK))

                        goto out;

        }

        if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {

                ret = -ENOMEM;

                goto out;

        }

        if (vma->vm_flags & VM_ACCOUNT) {

                charged = (new_len - old_len) >> PAGE_SHIFT;

                if (security_vm_enough_memory(charged))

                        goto out_nc;

        }

        /* old_len exactly to the end of the area..

         * And we're not relocating the area.

         */

        if (old_len == vma->vm_end - addr &&

            !((flags & MREMAP_FIXED) && (addr != new_addr)) &&

            (old_len != new_len || !(flags & MREMAP_MAYMOVE))) {

                unsigned long max_addr = TASK_SIZE;

                if (vma->vm_next)

                        max_addr = vma->vm_next->vm_start;

                /* can we just expand the current mapping? */

                if (max_addr - addr >= new_len) {

                        int pages = (new_len - old_len) >> PAGE_SHIFT;

                        vma_adjust(vma, vma->vm_start,

                                addr + new_len, vma->vm_pgoff, NULL);

                        mm->total_vm += pages;

                        vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);

                        if (vma->vm_flags & VM_LOCKED) {

                                mm->locked_vm += pages;

                                make_pages_present(addr + old_len,

                                                   addr + new_len);

                        }

                        ret = addr;

                        goto out;

                }

        }

        /*

         * We weren't able to just expand or shrink the area,

         * we need to create a new one and move it..

         */

        ret = -ENOMEM;

        if (flags & MREMAP_MAYMOVE) {

                if (!(flags & MREMAP_FIXED)) {

                        unsigned long map_flags = 0;

                        if (vma->vm_flags & VM_MAYSHARE)

                                map_flags |= MAP_SHARED;

                        new_addr = get_unmapped_area(vma->vm_file, 0, new_len,

                                                vma->vm_pgoff, map_flags);

                        if (new_addr & ~PAGE_MASK) {

                                ret = new_addr;

                                goto out;

                        }

                        ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);

                        if (ret)

                                goto out;

                }

                ret = move_vma(vma, addr, old_len, new_len, new_addr);

        }

out:

        if (ret & ~PAGE_MASK)

                vm_unacct_memory(charged);

out_nc:

        return ret;

}

asmlinkage unsigned long sys_mremap(unsigned long addr,

        unsigned long old_len, unsigned long new_len,

        unsigned long flags, unsigned long new_addr)

{

        unsigned long ret;

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

        ret = do_mremap(addr, old_len, new_len, flags, new_addr);

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

        return ret;

}