do_mremap() untangling, part 2
Take the MREMAP_FIXED into a separate helper, simplify the living hell out of conditions in both cases. Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
Родитель
54f5de7099
Коммит
ecc1a89937
118
mm/mremap.c
118
mm/mremap.c
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@ -313,6 +313,59 @@ Eagain:
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return ERR_PTR(-EAGAIN);
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}
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static unsigned long mremap_to(unsigned long addr,
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unsigned long old_len, unsigned long new_addr,
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unsigned long new_len)
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{
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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unsigned long ret = -EINVAL;
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unsigned long charged = 0;
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if (new_addr & ~PAGE_MASK)
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goto out;
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if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
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goto out;
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/* Check if the location we're moving into overlaps the
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* old location at all, and fail if it does.
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*/
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if ((new_addr <= addr) && (new_addr+new_len) > addr)
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goto out;
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if ((addr <= new_addr) && (addr+old_len) > new_addr)
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goto out;
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ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
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if (ret)
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goto out;
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ret = do_munmap(mm, new_addr, new_len);
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if (ret)
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goto out;
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if (old_len >= new_len) {
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ret = do_munmap(mm, addr+new_len, old_len - new_len);
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if (ret && old_len != new_len)
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goto out;
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old_len = new_len;
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}
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vma = vma_to_resize(addr, old_len, new_len, &charged);
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if (IS_ERR(vma)) {
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ret = PTR_ERR(vma);
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goto out;
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}
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ret = move_vma(vma, addr, old_len, new_len, new_addr);
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if (ret & ~PAGE_MASK)
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vm_unacct_memory(charged);
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out:
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return ret;
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}
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/*
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* Expand (or shrink) an existing mapping, potentially moving it at the
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* same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
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@ -346,32 +399,10 @@ unsigned long do_mremap(unsigned long addr,
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if (!new_len)
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goto out;
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/* new_addr is only valid if MREMAP_FIXED is specified */
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if (flags & MREMAP_FIXED) {
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if (new_addr & ~PAGE_MASK)
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goto out;
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if (!(flags & MREMAP_MAYMOVE))
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goto out;
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if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
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goto out;
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/* Check if the location we're moving into overlaps the
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* old location at all, and fail if it does.
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*/
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if ((new_addr <= addr) && (new_addr+new_len) > addr)
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goto out;
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if ((addr <= new_addr) && (addr+old_len) > new_addr)
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goto out;
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ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
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if (ret)
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goto out;
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ret = do_munmap(mm, new_addr, new_len);
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if (ret)
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goto out;
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if (flags & MREMAP_MAYMOVE)
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ret = mremap_to(addr, old_len, new_addr, new_len);
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goto out;
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}
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/*
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@ -384,13 +415,11 @@ unsigned long do_mremap(unsigned long addr,
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if (ret && old_len != new_len)
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goto out;
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ret = addr;
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if (!(flags & MREMAP_FIXED) || (new_addr == addr))
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goto out;
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old_len = new_len;
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goto out;
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}
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/*
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* Ok, we need to grow.. or relocate.
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* Ok, we need to grow..
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*/
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vma = vma_to_resize(addr, old_len, new_len, &charged);
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if (IS_ERR(vma)) {
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@ -399,11 +428,8 @@ unsigned long do_mremap(unsigned long addr,
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}
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/* old_len exactly to the end of the area..
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* And we're not relocating the area.
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*/
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if (old_len == vma->vm_end - addr &&
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!((flags & MREMAP_FIXED) && (addr != new_addr)) &&
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(old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
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if (old_len == vma->vm_end - addr) {
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unsigned long max_addr = TASK_SIZE;
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if (vma->vm_next)
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max_addr = vma->vm_next->vm_start;
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@ -432,22 +458,20 @@ unsigned long do_mremap(unsigned long addr,
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*/
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ret = -ENOMEM;
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if (flags & MREMAP_MAYMOVE) {
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if (!(flags & MREMAP_FIXED)) {
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unsigned long map_flags = 0;
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if (vma->vm_flags & VM_MAYSHARE)
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map_flags |= MAP_SHARED;
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unsigned long map_flags = 0;
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if (vma->vm_flags & VM_MAYSHARE)
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map_flags |= MAP_SHARED;
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new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
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vma->vm_pgoff, map_flags);
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if (new_addr & ~PAGE_MASK) {
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ret = new_addr;
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goto out;
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}
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ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
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if (ret)
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goto out;
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new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
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vma->vm_pgoff, map_flags);
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if (new_addr & ~PAGE_MASK) {
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ret = new_addr;
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goto out;
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}
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ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
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if (ret)
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goto out;
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ret = move_vma(vma, addr, old_len, new_len, new_addr);
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}
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out:
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