diff options
Diffstat (limited to 'xenolinux-2.4.24-sparse/mm/mremap.c')
| -rw-r--r-- | xenolinux-2.4.24-sparse/mm/mremap.c | 373 |
1 files changed, 373 insertions, 0 deletions
diff --git a/xenolinux-2.4.24-sparse/mm/mremap.c b/xenolinux-2.4.24-sparse/mm/mremap.c new file mode 100644 index 0000000000..2a0da0debc --- /dev/null +++ b/xenolinux-2.4.24-sparse/mm/mremap.c @@ -0,0 +1,373 @@ +/* + * linux/mm/remap.c + * + * (C) Copyright 1996 Linus Torvalds + */ + +#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> + +extern int vm_enough_memory(long pages); + +static inline pte_t *get_one_pte(struct mm_struct *mm, unsigned long addr) +{ + pgd_t * pgd; + 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; + } + + pmd = pmd_offset(pgd, 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(src); + 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: + XENO_flush_page_update_queue(); + flush_cache_range(mm, new_addr, new_addr + len); + while ((offset += PAGE_SIZE) < len) + move_one_page(mm, new_addr + offset, old_addr + offset); + XENO_flush_page_update_queue(); + zap_page_range(mm, new_addr, len); + return -1; +} + +static inline unsigned long move_vma(struct vm_area_struct * vma, + unsigned long 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, * next, * prev; + int allocated_vma; + + new_vma = NULL; + next = find_vma_prev(mm, new_addr, &prev); + if (next) { + if (prev && prev->vm_end == new_addr && + can_vma_merge(prev, vma->vm_flags) && !vma->vm_file && !(vma->vm_flags & VM_SHARED)) { + spin_lock(&mm->page_table_lock); + prev->vm_end = new_addr + new_len; + spin_unlock(&mm->page_table_lock); + new_vma = prev; + if (next != prev->vm_next) + BUG(); + if (prev->vm_end == next->vm_start && can_vma_merge(next, prev->vm_flags)) { + spin_lock(&mm->page_table_lock); + prev->vm_end = next->vm_end; + __vma_unlink(mm, next, prev); + spin_unlock(&mm->page_table_lock); + + mm->map_count--; + kmem_cache_free(vm_area_cachep, next); + } + } else if (next->vm_start == new_addr + new_len && + can_vma_merge(next, vma->vm_flags) && !vma->vm_file && !(vma->vm_flags & VM_SHARED)) { + spin_lock(&mm->page_table_lock); + next->vm_start = new_addr; + spin_unlock(&mm->page_table_lock); + new_vma = next; + } + } else { + prev = find_vma(mm, new_addr-1); + if (prev && prev->vm_end == new_addr && + can_vma_merge(prev, vma->vm_flags) && !vma->vm_file && !(vma->vm_flags & VM_SHARED)) { + spin_lock(&mm->page_table_lock); + prev->vm_end = new_addr + 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)) { + unsigned long vm_locked = vma->vm_flags & VM_LOCKED; + + if (allocated_vma) { + *new_vma = *vma; + new_vma->vm_start = new_addr; + new_vma->vm_end = new_addr+new_len; + new_vma->vm_pgoff += (addr-vma->vm_start) >> 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); + } + + do_munmap(current->mm, addr, old_len); + + current->mm->total_vm += new_len >> PAGE_SHIFT; + if (vm_locked) { + current->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; + } + 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 vm_area_struct *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; + /* + * Allow new_len == 0 only if new_addr == addr + * to preserve truncation in place (that was working + * safe and some app may depend on it). + */ + if (unlikely(!new_len && new_addr != addr)) + 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); + if (!vma || vma->vm_start > addr) + 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) { + if (new_len > old_len) + goto out; + } + if (vma->vm_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->vm_flags & (VM_SHARED | VM_WRITE)) == VM_WRITE && + !(flags & MAP_NORESERVE) && + !vm_enough_memory((new_len - old_len) >> PAGE_SHIFT)) + goto out; + +#if defined(CONFIG_XENO_PRIV) + /* mremap() unsupported for I/O mappings in Xenolinux. */ + ret = -EINVAL; + if (vma->vm_flags & VM_IO) + goto out; +#endif + + /* 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; + spin_lock(&vma->vm_mm->page_table_lock); + vma->vm_end = addr + new_len; + spin_unlock(&vma->vm_mm->page_table_lock); + current->mm->total_vm += pages; + if (vma->vm_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->vm_flags & VM_SHARED) + map_flags |= MAP_SHARED; + + new_addr = get_unmapped_area(vma->vm_file, 0, new_len, 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(¤t->mm->mmap_sem); + ret = do_mremap(addr, old_len, new_len, flags, new_addr); + up_write(¤t->mm->mmap_sem); + return ret; +} |