process_vm_access: switch to copy_page_to_iter/iov_iter_copy_from_user
... rather than open-coding those. As a side benefit, we get much saner loop calling those; we can just feed entire pages, instead of the "copy would span the iovec boundary, let's do it in two loop iterations" mess. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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@ -51,13 +51,11 @@ static int process_vm_rw_pages(struct task_struct *task,
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ssize_t *bytes_copied)
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{
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int pages_pinned;
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void *target_kaddr;
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int pgs_copied = 0;
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int j;
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int ret;
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ssize_t bytes_to_copy;
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ssize_t rc = 0;
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const struct iovec *iov = iter->iov;
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*bytes_copied = 0;
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@ -75,77 +73,34 @@ static int process_vm_rw_pages(struct task_struct *task,
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/* Do the copy for each page */
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for (pgs_copied = 0;
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(pgs_copied < nr_pages_to_copy) && iter->nr_segs;
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(pgs_copied < nr_pages_to_copy) && iov_iter_count(iter);
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pgs_copied++) {
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/* Make sure we have a non zero length iovec */
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while (iter->nr_segs && iov->iov_len == 0) {
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iov++;
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iter->nr_segs--;
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}
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if (!iter->nr_segs)
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break;
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struct page *page = process_pages[pgs_copied];
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bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset, len);
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/*
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* Will copy smallest of:
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* - bytes remaining in page
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* - bytes remaining in destination iovec
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*/
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bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset,
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len - *bytes_copied);
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bytes_to_copy = min_t(ssize_t, bytes_to_copy,
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iov->iov_len
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- iter->iov_offset);
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target_kaddr = kmap(process_pages[pgs_copied]) + start_offset;
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if (vm_write)
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ret = copy_from_user(target_kaddr,
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iov->iov_base
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+ iter->iov_offset,
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bytes_to_copy);
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else
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ret = copy_to_user(iov->iov_base
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+ iter->iov_offset,
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target_kaddr, bytes_to_copy);
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kunmap(process_pages[pgs_copied]);
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if (ret) {
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*bytes_copied += bytes_to_copy - ret;
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pgs_copied++;
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rc = -EFAULT;
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goto end;
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}
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*bytes_copied += bytes_to_copy;
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iter->iov_offset += bytes_to_copy;
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if (iter->iov_offset == iov->iov_len) {
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/*
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* Need to copy remaining part of page into the
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* next iovec if there are any bytes left in page
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*/
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iter->nr_segs--;
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iov++;
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iter->iov_offset = 0;
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start_offset = (start_offset + bytes_to_copy)
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% PAGE_SIZE;
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if (start_offset)
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pgs_copied--;
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if (vm_write) {
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if (bytes_to_copy > iov_iter_count(iter))
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bytes_to_copy = iov_iter_count(iter);
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ret = iov_iter_copy_from_user(page,
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iter, start_offset, bytes_to_copy);
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iov_iter_advance(iter, ret);
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set_page_dirty_lock(page);
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} else {
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start_offset = 0;
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ret = copy_page_to_iter(page, start_offset,
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bytes_to_copy, iter);
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}
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*bytes_copied += ret;
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len -= ret;
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if (ret < bytes_to_copy && iov_iter_count(iter)) {
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rc = -EFAULT;
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break;
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}
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start_offset = 0;
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}
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end:
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if (vm_write) {
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for (j = 0; j < pages_pinned; j++) {
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if (j < pgs_copied)
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set_page_dirty_lock(process_pages[j]);
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put_page(process_pages[j]);
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}
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} else {
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for (j = 0; j < pages_pinned; j++)
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put_page(process_pages[j]);
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}
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iter->iov = iov;
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return rc;
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}
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@ -194,7 +149,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
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return 0;
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nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
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while ((nr_pages_copied < nr_pages) && iter->nr_segs) {
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while ((nr_pages_copied < nr_pages) && iov_iter_count(iter)) {
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nr_pages_to_copy = min(nr_pages - nr_pages_copied,
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max_pages_per_loop);
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@ -303,7 +258,7 @@ static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
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goto put_task_struct;
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}
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for (i = 0; i < riovcnt && iter->nr_segs; i++) {
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for (i = 0; i < riovcnt && iov_iter_count(iter); i++) {
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rc = process_vm_rw_single_vec(
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(unsigned long)rvec[i].iov_base, rvec[i].iov_len,
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iter, process_pages, mm, task, vm_write,
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