Commit afa597ba authored by Carsten Otte's avatar Carsten Otte Committed by Linus Torvalds
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[PATCH] execute-in-place fixes 



This patch includes feedback from Andrew and Christoph. Thanks for
taking time to review.

Use of empty_zero_page was eliminated to fix compilation for architectures
that don't have it.

This patch removes setting pages up-to-date in ext2_get_xip_page and all
bug checks to verify that the page is indeed up to date.  Setting the page
state on mapping to userland is bogus.  None of the code patchs involved
with these pages in mm cares about the page state.

still on my ToDo list: identify a place outside second extended where
__inode_direct_access should reside

Signed-off-by: default avatarCarsten Otte <cotte@de.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c5287ba1

fs/ext2/xip.c

+47 −34
Original line number Diff line number Diff line
@@ -15,66 +15,79 @@ 
#include "xip.h"



static inline int

__inode_direct_access(struct inode *inode, sector_t sector, unsigned long *data) {

__inode_direct_access(struct inode *inode, sector_t sector,

		      unsigned long *data)

{

	BUG_ON(!inode->i_sb->s_bdev->bd_disk->fops->direct_access);

	return inode->i_sb->s_bdev->bd_disk->fops

		->direct_access(inode->i_sb->s_bdev,sector,data);

}



static inline int

__ext2_get_sector(struct inode *inode, sector_t offset, int create,

		   sector_t *result)

{

	struct buffer_head tmp;

	int rc;



	memset(&tmp, 0, sizeof(struct buffer_head));

	rc = ext2_get_block(inode, offset/ (PAGE_SIZE/512), &tmp,

			    create);

	*result = tmp.b_blocknr;



	/* did we get a sparse block (hole in the file)? */

	if (!(*result)) {

		BUG_ON(create);

		rc = -ENODATA;

	}



	return rc;

}



int

ext2_clear_xip_target(struct inode *inode, int block) {

ext2_clear_xip_target(struct inode *inode, int block)

{

	sector_t sector = block * (PAGE_SIZE/512);

	unsigned long data;

	int rc;



	rc = __inode_direct_access(inode, sector, &data);

	if (rc)

		return rc;

	if (!rc)

		clear_page((void*)data);

	return 0;

	return rc;

}



void ext2_xip_verify_sb(struct super_block *sb)

{

	struct ext2_sb_info *sbi = EXT2_SB(sb);



	if ((sbi->s_mount_opt & EXT2_MOUNT_XIP)) {

		if ((sb->s_bdev == NULL) ||

			sb->s_bdev->bd_disk == NULL ||

			sb->s_bdev->bd_disk->fops == NULL ||

			sb->s_bdev->bd_disk->fops->direct_access == NULL) {

	if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&

	    !sb->s_bdev->bd_disk->fops->direct_access) {

		sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);

		ext2_warning(sb, __FUNCTION__,

			     "ignoring xip option - not supported by bdev");

	}

}

}



struct page *

ext2_get_xip_page(struct address_space *mapping, sector_t blockno,

ext2_get_xip_page(struct address_space *mapping, sector_t offset,

		   int create)

{

	int rc;

	unsigned long data;

	struct buffer_head tmp;

	sector_t sector;



	tmp.b_state = 0;

	tmp.b_blocknr = 0;

	rc = ext2_get_block(mapping->host, blockno/(PAGE_SIZE/512) , &tmp,

				create);

	/* first, retrieve the sector number */

	rc = __ext2_get_sector(mapping->host, offset, create, &sector);

	if (rc)

		return ERR_PTR(rc);

	if (tmp.b_blocknr == 0) {

		/* SPARSE block */

		BUG_ON(create);

		return ERR_PTR(-ENODATA);

	}

		goto error;



	/* retrieve address of the target data */

	rc = __inode_direct_access

		(mapping->host,tmp.b_blocknr*(PAGE_SIZE/512) ,&data);

	if (rc)

		return ERR_PTR(rc);



	SetPageUptodate(virt_to_page(data));

		(mapping->host, sector * (PAGE_SIZE/512), &data);

	if (!rc)

		return virt_to_page(data);



 error:

	return ERR_PTR(rc);

}

mm/filemap_xip.c

+8 −15
Original line number Diff line number Diff line
@@ -68,13 +68,12 @@ do_xip_mapping_read(struct address_space *mapping, 
		if (unlikely(IS_ERR(page))) {

			if (PTR_ERR(page) == -ENODATA) {

				/* sparse */

				page = virt_to_page(empty_zero_page);

				page = ZERO_PAGE(0);

			} else {

				desc->error = PTR_ERR(page);

				goto out;

			}

		} else

			BUG_ON(!PageUptodate(page));

		}



		/* If users can be writing to this page using arbitrary

		 * virtual addresses, take care about potential aliasing
@@ -84,8 +83,7 @@ do_xip_mapping_read(struct address_space *mapping, 
			flush_dcache_page(page);



		/*

		 * Ok, we have the page, and it's up-to-date, so

		 * now we can copy it to user space...

		 * 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
@@ -164,7 +162,7 @@ EXPORT_SYMBOL_GPL(xip_file_sendfile); 
 * xip_write

 *

 * This function walks all vmas of the address_space and unmaps the

 * empty_zero_page when found at pgoff. Should it go in rmap.c?

 * ZERO_PAGE when found at pgoff. Should it go in rmap.c?

 */

static void

__xip_unmap (struct address_space * mapping,
@@ -187,7 +185,7 @@ __xip_unmap (struct address_space * mapping, 
		 * We need the page_table_lock to protect us from page faults,

		 * munmap, fork, etc...

		 */

		pte = page_check_address(virt_to_page(empty_zero_page), mm,

		pte = page_check_address(ZERO_PAGE(address), mm,

					 address);

		if (!IS_ERR(pte)) {

			/* Nuke the page table entry. */
@@ -230,7 +228,6 @@ xip_file_nopage(struct vm_area_struct * area, 


	page = mapping->a_ops->get_xip_page(mapping, pgoff*(PAGE_SIZE/512), 0);

	if (!IS_ERR(page)) {

		BUG_ON(!PageUptodate(page));

		return page;

	}

	if (PTR_ERR(page) != -ENODATA)
@@ -245,12 +242,11 @@ xip_file_nopage(struct vm_area_struct * area, 
			pgoff*(PAGE_SIZE/512), 1);

		if (IS_ERR(page))

			return NULL;

		BUG_ON(!PageUptodate(page));

		/* unmap page at pgoff from all other vmas */

		__xip_unmap(mapping, pgoff);

	} else {

		/* not shared and writable, use empty_zero_page */

		page = virt_to_page(empty_zero_page);

		/* not shared and writable, use ZERO_PAGE() */

		page = ZERO_PAGE(address);

	}



	return page;
@@ -319,8 +315,6 @@ __xip_file_write(struct file *filp, const char __user *buf, 
			break;

		}



		BUG_ON(!PageUptodate(page));



		copied = filemap_copy_from_user(page, offset, buf, bytes);

		flush_dcache_page(page);

		if (likely(copied > 0)) {
@@ -435,8 +429,7 @@ xip_truncate_page(struct address_space *mapping, loff_t from) 
			return 0;

		else

			return PTR_ERR(page);

	} else

		BUG_ON(!PageUptodate(page));

	}

	kaddr = kmap_atomic(page, KM_USER0);

	memset(kaddr + offset, 0, length);

	kunmap_atomic(kaddr, KM_USER0);

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