sys/src/vmsmremap.c

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// _Id: vmsmremap.c,v 1.8 2006-07-10 15:44:07 roart Exp $
// _Locker:  $

// Author. Roar Thronæs.
// Modified Linux source file, 2001-2004. Based on mremap.c.

/*
 *      linux/mm/remap.c
 *
 *      (C) Copyright 1996 Linus Torvalds
 */

#include <linux/config.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <linux/swap.h>

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

#include <ipldef.h>
#include <phddef.h>
#include <rdedef.h>
#include <misc_routines.h>

extern int vm_enough_memory(long pages);

static inline pte_t *get_one_pte(struct mm_struct *mm, unsigned long addr)
{
        pgd_t * pgd;
        pud_t * pud;
        pmd_t * pmd;
        pte_t * pte = NULL;

        pgd = pgd_offset(mm, addr);
        if (pgd_none(*pgd))
                goto end;
        if (pgd_bad(*pgd)) {
                pgd_ERROR(*pgd);
                pgd_clear(pgd);
                goto end;
        }

        pud = pud_offset(pgd, addr);
        if (pud_none(*pud))
                goto end;
        if (pud_bad(*pud)) {
                pud_ERROR(*pud);
                pud_clear(pud);
                goto end;
        }

        pmd = pmd_offset(pud, addr);
        if (pmd_none(*pmd))
                goto end;
        if (pmd_bad(*pmd)) {
                pmd_ERROR(*pmd);
                pmd_clear(pmd);
                goto end;
        }

        pte = pte_offset(pmd, addr);
        if (pte_none(*pte))
                pte = NULL;
end:
        return pte;
}

static inline pte_t *alloc_one_pte(struct mm_struct *mm, unsigned long addr)
{
        pmd_t * pmd;
        pte_t * pte = NULL;

        pmd = pmd_alloc(mm, pgd_offset(mm, addr), addr);
        if (pmd)
                pte = pte_alloc(mm, pmd, addr);
        return pte;
}

static inline int copy_one_pte(struct mm_struct *mm, pte_t * src, pte_t * dst)
{
        int error = 0;
        pte_t pte;

        if (!pte_none(*src)) {
          pte = ptep_get_and_clear(42, 42, src); // check
                if (!dst) {
                        /* No dest?  We must put it back. */
                        dst = src;
                        error++;
                }
                set_pte(dst, pte);
        }
        return error;
}

static int move_one_page(struct mm_struct *mm, unsigned long old_addr, unsigned long new_addr)
{
        int error = 0;
        pte_t * src;

        spin_lock(&mm->page_table_lock);
        src = get_one_pte(mm, old_addr);
        if (src)
                error = copy_one_pte(mm, src, alloc_one_pte(mm, new_addr));
        spin_unlock(&mm->page_table_lock);
        return error;
}

static int move_page_tables(struct mm_struct * mm,
        unsigned long new_addr, unsigned long old_addr, unsigned long len)
{
        unsigned long offset = len;

        flush_cache_range(mm, old_addr, old_addr + len);

        /*
         * This is not the clever way to do this, but we're taking the
         * easy way out on the assumption that most remappings will be
         * only a few pages.. This also makes error recovery easier.
         */
        while (offset) {
                offset -= PAGE_SIZE;
                if (move_one_page(mm, old_addr + offset, new_addr + offset))
                        goto oops_we_failed;
        }
        flush_tlb_range(mm, old_addr, old_addr + len);
        return 0;

        /*
         * Ok, the move failed because we didn't have enough pages for
         * the new page table tree. This is unlikely, but we have to
         * take the possibility into account. In that case we just move
         * all the pages back (this will work, because we still have
         * the old page tables)
         */
oops_we_failed:
        flush_cache_range(mm, new_addr, new_addr + len);
        while ((offset += PAGE_SIZE) < len)
                move_one_page(mm, new_addr + offset, old_addr + offset);
        zap_page_range(mm, new_addr, len);
        return -1;
}

static inline unsigned long move_vma(struct _rde * vma,
        unsigned long addr, unsigned long old_len, unsigned long new_len,
        unsigned long new_addr)
{
  struct mm_struct * mm = current->mm;//vma->vm_mm;
        struct _rde * new_vma, * next, * prev;
        int allocated_vma;

        new_vma = NULL;
        //next = find_vma_prev(mm, new_addr, &prev);
        next = find_vma_prev(current->pcb_l_phd,new_addr,&prev);
        if (next) {
                if (prev && (prev->rde_pq_start_va + prev->rde$q_region_size) == new_addr &&
                    can_vma_merge(prev, vma->rde_l_flags) /*&& !vma->vm_file */&& !(vma->rde$l_flags & VM_SHARED)) {
                        spin_lock(&mm->page_table_lock);
                        prev->rde_q_region_size = new_len;
                        spin_unlock(&mm->page_table_lock);
                        new_vma = prev;
                        if (next != prev->rde_ps_va_list_flink)
                                BUG();
                        if ((prev->rde_pq_start_va + prev->rde$q_region_size) == next->rde$pq_start_va && can_vma_merge(next, prev->rde$l_flags)) {
                                spin_lock(&mm->page_table_lock);
                                prev->rde_q_region_size = next->rde$q_region_size;
#if 0
                                __vma_unlink(mm, next, prev);
#endif
                                spin_unlock(&mm->page_table_lock);

                                mm->map_count--;
                                kmem_cache_free(vm_area_cachep, next);
                        }
                } else if (next->rde_pq_start_va == new_addr + new_len &&
                           can_vma_merge(next, vma->rde_l_flags) /*&& !vma->vm_file*/ && !(vma->rde$l_flags & VM_SHARED)) {
                        spin_lock(&mm->page_table_lock);
                        next->rde_pq_start_va = new_addr;
                        spin_unlock(&mm->page_table_lock);
                        new_vma = next;
                }
        } else {
          //prev = find_vma(mm, new_addr-1);
          prev = find_vma(current->pcb_l_phd,new_addr-1);
                if (prev && (prev->rde_pq_start_va + prev->rde$q_region_size) == new_addr &&
                    can_vma_merge(prev, vma->rde_l_flags) /*&& !vma->vm_file*/ && !(vma->rde$l_flags & VM_SHARED)) {
                        spin_lock(&mm->page_table_lock);
                        prev->rde_q_region_size = new_len;
                        spin_unlock(&mm->page_table_lock);
                        new_vma = prev;
                }
        }

        allocated_vma = 0;
        if (!new_vma) {
                new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
                if (!new_vma)
                        goto out;
                allocated_vma = 1;
        }

        if (!move_page_tables(current->mm, new_addr, addr, old_len)) {
                if (allocated_vma) {
                        *new_vma = *vma;
                        new_vma->rde_pq_start_va = new_addr;
                        new_vma->rde_q_region_size = new_len;
#if 0
                        new_vma->vm_pgoff += (addr - vma->rde_pq_start_va) >> PAGE_SHIFT;
                        new_vma->vm_raend = 0;
                        if (new_vma->vm_file)
                                get_file(new_vma->vm_file);
                        if (new_vma->vm_ops && new_vma->vm_ops->open)
                                new_vma->vm_ops->open(new_vma);
                        insert_vm_struct(current->mm, new_vma);
#endif
                        insrde(new_vma,&current->pcb_l_phd->phd$ps_p0_va_list_flink);
                }
                do_munmap(current->mm, addr, old_len);
                current->mm->total_vm += new_len >> PAGE_SHIFT;
                if (new_vma->rde_l_flags & VM_LOCKED) {
                        current->mm->locked_vm += new_len >> PAGE_SHIFT;
                        make_pages_present(new_vma->rde_pq_start_va,
                                           (new_vma->rde_pq_start_va + new_vma->rde$q_region_size));
                }
                return new_addr;
        }
        if (allocated_vma)
                kmem_cache_free(vm_area_cachep, new_vma);
 out:
        return -ENOMEM;
}

/*
 * 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 _rde *vma;
        unsigned long ret = -EINVAL;

        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);

        /* 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;

                do_munmap(current->mm, new_addr, new_len);
        }

        /*
         * Always allow a shrinking remap: that just unmaps
         * the unnecessary pages..
         */
        ret = addr;
        if (old_len >= new_len) {
                do_munmap(current->mm, addr+new_len, old_len - new_len);
                if (!(flags & MREMAP_FIXED) || (new_addr == addr))
                        goto out;
        }

        /*
         * Ok, we need to grow..  or relocate.
         */
        ret = -EFAULT;
        //vma = find_vma(current->mm, addr);
        vma = find_vma(current->pcb_l_phd,addr);
        if (!vma || vma->rde_pq_start_va > addr)
                goto out;
        /* We can't remap across vm area boundaries */
        if (old_len > (vma->rde_pq_start_va + vma->rde$q_region_size) - addr)
                goto out;
        if (vma->rde_l_flags & VM_DONTEXPAND) {
                if (new_len > old_len)
                        goto out;
        }
        if (vma->rde_l_flags & VM_LOCKED) {
                unsigned long locked = current->mm->locked_vm << PAGE_SHIFT;
                locked += new_len - old_len;
                ret = -EAGAIN;
                if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur)
                        goto out;
        }
        ret = -ENOMEM;
        if ((current->mm->total_vm << PAGE_SHIFT) + (new_len - old_len)
            > current->rlim[RLIMIT_AS].rlim_cur)
                goto out;
        /* Private writable mapping? Check memory availability.. */
        if ((vma->rde_l_flags & (VM_SHARED | VM_WRITE)) == VM_WRITE &&
            !(flags & MAP_NORESERVE)                             &&
            !vm_enough_memory((new_len - old_len) >> PAGE_SHIFT))
                goto out;

        /* old_len exactly to the end of the area..
         * And we're not relocating the area.
         */
        if (old_len == (vma->rde_pq_start_va + vma->rde$q_region_size) - addr &&
            !((flags & MREMAP_FIXED) && (addr != new_addr)) &&
            (old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
                unsigned long max_addr = TASK_SIZE;
                if (vma->rde_ps_va_list_flink)
                        max_addr = vma->rde_ps_va_list_flink->rde$pq_start_va;
                /* can we just expand the current mapping? */
                if (max_addr - addr >= new_len) {
                        int pages = (new_len - old_len) >> PAGE_SHIFT;
                        //spin_lock(&vma->vm_mm->page_table_lock);
                        vma->rde_q_region_size = new_len;
                        //spin_unlock(&vma->vm_mm->page_table_lock);
                        current->mm->total_vm += pages;
                        if (vma->rde_l_flags & VM_LOCKED) {
                                current->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->rde_l_flags & VM_SHARED)
                                map_flags |= MAP_SHARED;

                        new_addr = get_unmapped_area(0/*vma->vm_file*/, 0, new_len, 0/*vma->vm_pgoff*/, map_flags);
                        ret = new_addr;
                        if (new_addr & ~PAGE_MASK)
                                goto out;
                }
                ret = move_vma(vma, addr, old_len, new_len, new_addr);
        }
out:
        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;
}

---