--- /dev/null
+/*
+ * linux/mm/filemap_xip.c
+ *
+ * Copyright (C) 2005 IBM Corporation
+ * Author: Carsten Otte <cotte@de.ibm.com>
+ *
+ * derived from linux/mm/filemap.c - Copyright (C) Linus Torvalds
+ *
+ */
+
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/module.h>
+#include <linux/uio.h>
+#include <linux/rmap.h>
+#include <asm/tlbflush.h>
+#include "filemap.h"
+
+/*
+ * This is a file read routine for execute in place files, and uses
+ * the mapping->a_ops->get_xip_page() function for the actual low-level
+ * stuff.
+ *
+ * Note the struct file* is not used at all. It may be NULL.
+ */
+static void
+do_xip_mapping_read(struct address_space *mapping,
+ struct file_ra_state *_ra,
+ struct file *filp,
+ loff_t *ppos,
+ read_descriptor_t *desc,
+ read_actor_t actor)
+{
+ struct inode *inode = mapping->host;
+ unsigned long index, end_index, offset;
+ loff_t isize;
+
+ BUG_ON(!mapping->a_ops->get_xip_page);
+
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ offset = *ppos & ~PAGE_CACHE_MASK;
+
+ isize = i_size_read(inode);
+ if (!isize)
+ goto out;
+
+ end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
+ for (;;) {
+ struct page *page;
+ unsigned long nr, ret;
+
+ /* nr is the maximum number of bytes to copy from this page */
+ nr = PAGE_CACHE_SIZE;
+ if (index >= end_index) {
+ if (index > end_index)
+ goto out;
+ nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
+ if (nr <= offset) {
+ goto out;
+ }
+ }
+ nr = nr - offset;
+
+ page = mapping->a_ops->get_xip_page(mapping,
+ index*(PAGE_SIZE/512), 0);
+ if (!page)
+ goto no_xip_page;
+ if (unlikely(IS_ERR(page))) {
+ if (PTR_ERR(page) == -ENODATA) {
+ /* sparse */
+ page = ZERO_PAGE(0);
+ } else {
+ desc->error = PTR_ERR(page);
+ goto out;
+ }
+ }
+
+ /* If users can be writing to this page using arbitrary
+ * virtual addresses, take care about potential aliasing
+ * before reading the page on the kernel side.
+ */
+ if (mapping_writably_mapped(mapping))
+ flush_dcache_page(page);
+
+ /*
+ * Ok, we have the page, so now we can copy it to user space...
+ *
+ * The actor routine returns how many bytes were actually used..
+ * NOTE! This may not be the same as how much of a user buffer
+ * we filled up (we may be padding etc), so we can only update
+ * "pos" here (the actor routine has to update the user buffer
+ * pointers and the remaining count).
+ */
+ ret = actor(desc, page, offset, nr);
+ offset += ret;
+ index += offset >> PAGE_CACHE_SHIFT;
+ offset &= ~PAGE_CACHE_MASK;
+
+ if (ret == nr && desc->count)
+ continue;
+ goto out;
+
+no_xip_page:
+ /* Did not get the page. Report it */
+ desc->error = -EIO;
+ goto out;
+ }
+
+out:
+ *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
+ if (filp)
+ file_accessed(filp);
+}
+
+ssize_t
+xip_file_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
+{
+ read_descriptor_t desc;
+
+ if (!access_ok(VERIFY_WRITE, buf, len))
+ return -EFAULT;
+
+ desc.written = 0;
+ desc.arg.buf = buf;
+ desc.count = len;
+ desc.error = 0;
+
+ do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp,
+ ppos, &desc, file_read_actor);
+
+ if (desc.written)
+ return desc.written;
+ else
+ return desc.error;
+}
+EXPORT_SYMBOL_GPL(xip_file_read);
+
+ssize_t
+xip_file_sendfile(struct file *in_file, loff_t *ppos,
+ size_t count, read_actor_t actor, void *target)
+{
+ read_descriptor_t desc;
+
+ if (!count)
+ return 0;
+
+ desc.written = 0;
+ desc.count = count;
+ desc.arg.data = target;
+ desc.error = 0;
+
+ do_xip_mapping_read(in_file->f_mapping, &in_file->f_ra, in_file,
+ ppos, &desc, actor);
+ if (desc.written)
+ return desc.written;
+ return desc.error;
+}
+EXPORT_SYMBOL_GPL(xip_file_sendfile);
+
+/*
+ * __xip_unmap is invoked from xip_unmap and
+ * xip_write
+ *
+ * This function walks all vmas of the address_space and unmaps the
+ * ZERO_PAGE when found at pgoff. Should it go in rmap.c?
+ */
+static void
+__xip_unmap (struct address_space * mapping,
+ unsigned long pgoff)
+{
+ struct vm_area_struct *vma;
+ struct mm_struct *mm;
+ struct prio_tree_iter iter;
+ unsigned long address;
+ pte_t *pte;
+ pte_t pteval;
+ spinlock_t *ptl;
+ struct page *page;
+
+ spin_lock(&mapping->i_mmap_lock);
+ vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
+ mm = vma->vm_mm;
+ address = vma->vm_start +
+ ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+ BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+ page = ZERO_PAGE(address);
+ pte = page_check_address(page, mm, address, &ptl);
+ if (pte) {
+ /* Nuke the page table entry. */
+ flush_cache_page(vma, address, pte_pfn(*pte));
+ pteval = ptep_clear_flush(vma, address, pte);
+ page_remove_rmap(page);
+ dec_mm_counter(mm, file_rss);
+ BUG_ON(pte_dirty(pteval));
+ pte_unmap_unlock(pte, ptl);
+ page_cache_release(page);
+ }
+ }
+ spin_unlock(&mapping->i_mmap_lock);
+}
+
+/*
+ * xip_nopage() is invoked via the vma operations vector for a
+ * mapped memory region to read in file data during a page fault.
+ *
+ * This function is derived from filemap_nopage, but used for execute in place
+ */
+static struct page *
+xip_file_nopage(struct vm_area_struct * area,
+ unsigned long address,
+ int *type)
+{
+ struct file *file = area->vm_file;
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
+ struct page *page;
+ unsigned long size, pgoff, endoff;
+
+ pgoff = ((address - area->vm_start) >> PAGE_CACHE_SHIFT)
+ + area->vm_pgoff;
+ endoff = ((area->vm_end - area->vm_start) >> PAGE_CACHE_SHIFT)
+ + area->vm_pgoff;
+
+ size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ if (pgoff >= size) {
+ return NULL;
+ }
+
+ page = mapping->a_ops->get_xip_page(mapping, pgoff*(PAGE_SIZE/512), 0);
+ if (!IS_ERR(page)) {
+ goto out;
+ }
+ if (PTR_ERR(page) != -ENODATA)
+ return NULL;
+
+ /* sparse block */
+ if ((area->vm_flags & (VM_WRITE | VM_MAYWRITE)) &&
+ (area->vm_flags & (VM_SHARED| VM_MAYSHARE)) &&
+ (!(mapping->host->i_sb->s_flags & MS_RDONLY))) {
+ /* maybe shared writable, allocate new block */
+ page = mapping->a_ops->get_xip_page (mapping,
+ pgoff*(PAGE_SIZE/512), 1);
+ if (IS_ERR(page))
+ return NULL;
+ /* unmap page at pgoff from all other vmas */
+ __xip_unmap(mapping, pgoff);
+ } else {
+ /* not shared and writable, use ZERO_PAGE() */
+ page = ZERO_PAGE(address);
+ }
+
+out:
+ page_cache_get(page);
+ return page;
+}
+
+static struct vm_operations_struct xip_file_vm_ops = {
+ .nopage = xip_file_nopage,
+};
+
+int xip_file_mmap(struct file * file, struct vm_area_struct * vma)
+{
+ BUG_ON(!file->f_mapping->a_ops->get_xip_page);
+
+ file_accessed(file);
+ vma->vm_ops = &xip_file_vm_ops;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xip_file_mmap);
+
+static ssize_t
+__xip_file_write(struct file *filp, const char __user *buf,
+ size_t count, loff_t pos, loff_t *ppos)
+{
+ struct address_space * mapping = filp->f_mapping;
+ struct address_space_operations *a_ops = mapping->a_ops;
+ struct inode *inode = mapping->host;
+ long status = 0;
+ struct page *page;
+ size_t bytes;
+ ssize_t written = 0;
+
+ BUG_ON(!mapping->a_ops->get_xip_page);
+
+ do {
+ unsigned long index;
+ unsigned long offset;
+ size_t copied;
+
+ offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
+ index = pos >> PAGE_CACHE_SHIFT;
+ bytes = PAGE_CACHE_SIZE - offset;
+ if (bytes > count)
+ bytes = count;
+
+ /*
+ * Bring in the user page that we will copy from _first_.
+ * Otherwise there's a nasty deadlock on copying from the
+ * same page as we're writing to, without it being marked
+ * up-to-date.
+ */
+ fault_in_pages_readable(buf, bytes);
+
+ page = a_ops->get_xip_page(mapping,
+ index*(PAGE_SIZE/512), 0);
+ if (IS_ERR(page) && (PTR_ERR(page) == -ENODATA)) {
+ /* we allocate a new page unmap it */
+ page = a_ops->get_xip_page(mapping,
+ index*(PAGE_SIZE/512), 1);
+ if (!IS_ERR(page))
+ /* unmap page at pgoff from all other vmas */
+ __xip_unmap(mapping, index);
+ }
+
+ if (IS_ERR(page)) {
+ status = PTR_ERR(page);
+ break;
+ }
+
+ copied = filemap_copy_from_user(page, offset, buf, bytes);
+ flush_dcache_page(page);
+ if (likely(copied > 0)) {
+ status = copied;
+
+ if (status >= 0) {
+ written += status;
+ count -= status;
+ pos += status;
+ buf += status;
+ }
+ }
+ if (unlikely(copied != bytes))
+ if (status >= 0)
+ status = -EFAULT;
+ if (status < 0)
+ break;
+ } while (count);
+ *ppos = pos;
+ /*
+ * No need to use i_size_read() here, the i_size
+ * cannot change under us because we hold i_mutex.
+ */
+ if (pos > inode->i_size) {
+ i_size_write(inode, pos);
+ mark_inode_dirty(inode);
+ }
+
+ return written ? written : status;
+}
+
+ssize_t
+xip_file_write(struct file *filp, const char __user *buf, size_t len,
+ loff_t *ppos)
+{
+ struct address_space *mapping = filp->f_mapping;
+ struct inode *inode = mapping->host;
+ size_t count;
+ loff_t pos;
+ ssize_t ret;
+
+ mutex_lock(&inode->i_mutex);
+
+ if (!access_ok(VERIFY_READ, buf, len)) {
+ ret=-EFAULT;
+ goto out_up;
+ }
+
+ pos = *ppos;
+ count = len;
+
+ vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+
+ /* We can write back this queue in page reclaim */
+ current->backing_dev_info = mapping->backing_dev_info;
+
+ ret = generic_write_checks(filp, &pos, &count, S_ISBLK(inode->i_mode));
+ if (ret)
+ goto out_backing;
+ if (count == 0)
+ goto out_backing;
+
+ ret = remove_suid(filp->f_dentry);
+ if (ret)
+ goto out_backing;
+
+ file_update_time(filp);
+
+ ret = __xip_file_write (filp, buf, count, pos, ppos);
+
+ out_backing:
+ current->backing_dev_info = NULL;
+ out_up:
+ mutex_unlock(&inode->i_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(xip_file_write);
+
+/*
+ * truncate a page used for execute in place
+ * functionality is analog to block_truncate_page but does use get_xip_page
+ * to get the page instead of page cache
+ */
+int
+xip_truncate_page(struct address_space *mapping, loff_t from)
+{
+ pgoff_t index = from >> PAGE_CACHE_SHIFT;
+ unsigned offset = from & (PAGE_CACHE_SIZE-1);
+ unsigned blocksize;
+ unsigned length;
+ struct page *page;
+ void *kaddr;
+
+ BUG_ON(!mapping->a_ops->get_xip_page);
+
+ blocksize = 1 << mapping->host->i_blkbits;
+ length = offset & (blocksize - 1);
+
+ /* Block boundary? Nothing to do */
+ if (!length)
+ return 0;
+
+ length = blocksize - length;
+
+ page = mapping->a_ops->get_xip_page(mapping,
+ index*(PAGE_SIZE/512), 0);
+ if (!page)
+ return -ENOMEM;
+ if (unlikely(IS_ERR(page))) {
+ if (PTR_ERR(page) == -ENODATA)
+ /* Hole? No need to truncate */
+ return 0;
+ else
+ return PTR_ERR(page);
+ }
+ kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr + offset, 0, length);
+ kunmap_atomic(kaddr, KM_USER0);
+
+ flush_dcache_page(page);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xip_truncate_page);
git://git.onelab.eu / linux-2.6.git / blobdiff