blob: 847d5d78163e4a4de5c26051839ac64c3a6ee227 [file] [log] [blame]
Carsten Otteceffc072005-06-23 22:05:25 -07001/*
2 * linux/mm/filemap_xip.c
3 *
4 * Copyright (C) 2005 IBM Corporation
5 * Author: Carsten Otte <cotte@de.ibm.com>
6 *
7 * derived from linux/mm/filemap.c - Copyright (C) Linus Torvalds
8 *
9 */
10
11#include <linux/fs.h>
12#include <linux/pagemap.h>
13#include <linux/module.h>
14#include <linux/uio.h>
15#include <linux/rmap.h>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040016#include <linux/sched.h>
Carsten Otteceffc072005-06-23 22:05:25 -070017#include <asm/tlbflush.h>
18#include "filemap.h"
19
20/*
Carsten Ottea76c0b92007-03-29 01:20:39 -070021 * We do use our own empty page to avoid interference with other users
22 * of ZERO_PAGE(), such as /dev/zero
23 */
24static struct page *__xip_sparse_page;
25
26static struct page *xip_sparse_page(void)
27{
28 if (!__xip_sparse_page) {
29 unsigned long zeroes = get_zeroed_page(GFP_HIGHUSER);
30 if (zeroes) {
31 static DEFINE_SPINLOCK(xip_alloc_lock);
32 spin_lock(&xip_alloc_lock);
33 if (!__xip_sparse_page)
34 __xip_sparse_page = virt_to_page(zeroes);
35 else
36 free_page(zeroes);
37 spin_unlock(&xip_alloc_lock);
38 }
39 }
40 return __xip_sparse_page;
41}
42
43/*
Carsten Otteceffc072005-06-23 22:05:25 -070044 * This is a file read routine for execute in place files, and uses
45 * the mapping->a_ops->get_xip_page() function for the actual low-level
46 * stuff.
47 *
48 * Note the struct file* is not used at all. It may be NULL.
49 */
50static void
51do_xip_mapping_read(struct address_space *mapping,
52 struct file_ra_state *_ra,
53 struct file *filp,
54 loff_t *ppos,
55 read_descriptor_t *desc,
56 read_actor_t actor)
57{
58 struct inode *inode = mapping->host;
59 unsigned long index, end_index, offset;
60 loff_t isize;
61
62 BUG_ON(!mapping->a_ops->get_xip_page);
63
64 index = *ppos >> PAGE_CACHE_SHIFT;
65 offset = *ppos & ~PAGE_CACHE_MASK;
66
67 isize = i_size_read(inode);
68 if (!isize)
69 goto out;
70
71 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
72 for (;;) {
73 struct page *page;
74 unsigned long nr, ret;
75
76 /* nr is the maximum number of bytes to copy from this page */
77 nr = PAGE_CACHE_SIZE;
78 if (index >= end_index) {
79 if (index > end_index)
80 goto out;
81 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
82 if (nr <= offset) {
83 goto out;
84 }
85 }
86 nr = nr - offset;
87
88 page = mapping->a_ops->get_xip_page(mapping,
89 index*(PAGE_SIZE/512), 0);
90 if (!page)
91 goto no_xip_page;
92 if (unlikely(IS_ERR(page))) {
93 if (PTR_ERR(page) == -ENODATA) {
94 /* sparse */
Carsten Otteafa597b2005-07-15 03:56:30 -070095 page = ZERO_PAGE(0);
Carsten Otteceffc072005-06-23 22:05:25 -070096 } else {
97 desc->error = PTR_ERR(page);
98 goto out;
99 }
Carsten Otteafa597b2005-07-15 03:56:30 -0700100 }
Carsten Otteceffc072005-06-23 22:05:25 -0700101
102 /* If users can be writing to this page using arbitrary
103 * virtual addresses, take care about potential aliasing
104 * before reading the page on the kernel side.
105 */
106 if (mapping_writably_mapped(mapping))
107 flush_dcache_page(page);
108
109 /*
Carsten Otteafa597b2005-07-15 03:56:30 -0700110 * Ok, we have the page, so now we can copy it to user space...
Carsten Otteceffc072005-06-23 22:05:25 -0700111 *
112 * The actor routine returns how many bytes were actually used..
113 * NOTE! This may not be the same as how much of a user buffer
114 * we filled up (we may be padding etc), so we can only update
115 * "pos" here (the actor routine has to update the user buffer
116 * pointers and the remaining count).
117 */
118 ret = actor(desc, page, offset, nr);
119 offset += ret;
120 index += offset >> PAGE_CACHE_SHIFT;
121 offset &= ~PAGE_CACHE_MASK;
122
123 if (ret == nr && desc->count)
124 continue;
125 goto out;
126
127no_xip_page:
128 /* Did not get the page. Report it */
129 desc->error = -EIO;
130 goto out;
131 }
132
133out:
134 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
135 if (filp)
136 file_accessed(filp);
137}
138
Carsten Otteceffc072005-06-23 22:05:25 -0700139ssize_t
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700140xip_file_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
Carsten Otteceffc072005-06-23 22:05:25 -0700141{
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700142 read_descriptor_t desc;
Carsten Otteceffc072005-06-23 22:05:25 -0700143
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700144 if (!access_ok(VERIFY_WRITE, buf, len))
145 return -EFAULT;
146
147 desc.written = 0;
148 desc.arg.buf = buf;
149 desc.count = len;
150 desc.error = 0;
151
152 do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp,
153 ppos, &desc, file_read_actor);
154
155 if (desc.written)
156 return desc.written;
157 else
158 return desc.error;
Carsten Otteceffc072005-06-23 22:05:25 -0700159}
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700160EXPORT_SYMBOL_GPL(xip_file_read);
Carsten Otteceffc072005-06-23 22:05:25 -0700161
Carsten Otteceffc072005-06-23 22:05:25 -0700162/*
163 * __xip_unmap is invoked from xip_unmap and
164 * xip_write
165 *
166 * This function walks all vmas of the address_space and unmaps the
Carsten Ottea76c0b92007-03-29 01:20:39 -0700167 * __xip_sparse_page when found at pgoff.
Carsten Otteceffc072005-06-23 22:05:25 -0700168 */
169static void
170__xip_unmap (struct address_space * mapping,
171 unsigned long pgoff)
172{
173 struct vm_area_struct *vma;
174 struct mm_struct *mm;
175 struct prio_tree_iter iter;
176 unsigned long address;
177 pte_t *pte;
178 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700179 spinlock_t *ptl;
Hugh Dickins67b02f12005-10-29 18:16:31 -0700180 struct page *page;
Carsten Otteceffc072005-06-23 22:05:25 -0700181
Carsten Ottea76c0b92007-03-29 01:20:39 -0700182 page = __xip_sparse_page;
183 if (!page)
184 return;
185
Carsten Otteceffc072005-06-23 22:05:25 -0700186 spin_lock(&mapping->i_mmap_lock);
187 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
188 mm = vma->vm_mm;
189 address = vma->vm_start +
190 ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
191 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Hugh Dickinsc0718802005-10-29 18:16:31 -0700192 pte = page_check_address(page, mm, address, &ptl);
193 if (pte) {
Carsten Otteceffc072005-06-23 22:05:25 -0700194 /* Nuke the page table entry. */
Geert Uytterhoeven082ff0a2005-07-12 13:58:18 -0700195 flush_cache_page(vma, address, pte_pfn(*pte));
Carsten Otteceffc072005-06-23 22:05:25 -0700196 pteval = ptep_clear_flush(vma, address, pte);
Nick Piggin7de6b802006-12-22 01:09:33 -0800197 page_remove_rmap(page, vma);
Nick Pigginb5810032005-10-29 18:16:12 -0700198 dec_mm_counter(mm, file_rss);
Carsten Otteceffc072005-06-23 22:05:25 -0700199 BUG_ON(pte_dirty(pteval));
Hugh Dickinsc0718802005-10-29 18:16:31 -0700200 pte_unmap_unlock(pte, ptl);
Nick Pigginb5810032005-10-29 18:16:12 -0700201 page_cache_release(page);
Carsten Otteceffc072005-06-23 22:05:25 -0700202 }
203 }
204 spin_unlock(&mapping->i_mmap_lock);
205}
206
207/*
Nick Piggin54cb8822007-07-19 01:46:59 -0700208 * xip_fault() is invoked via the vma operations vector for a
Carsten Otteceffc072005-06-23 22:05:25 -0700209 * mapped memory region to read in file data during a page fault.
210 *
Nick Piggin54cb8822007-07-19 01:46:59 -0700211 * This function is derived from filemap_fault, but used for execute in place
Carsten Otteceffc072005-06-23 22:05:25 -0700212 */
Nick Piggind0217ac2007-07-19 01:47:03 -0700213static int xip_file_fault(struct vm_area_struct *area, struct vm_fault *vmf)
Carsten Otteceffc072005-06-23 22:05:25 -0700214{
215 struct file *file = area->vm_file;
216 struct address_space *mapping = file->f_mapping;
217 struct inode *inode = mapping->host;
218 struct page *page;
Nick Piggin54cb8822007-07-19 01:46:59 -0700219 pgoff_t size;
Carsten Otteceffc072005-06-23 22:05:25 -0700220
Nick Piggin54cb8822007-07-19 01:46:59 -0700221 /* XXX: are VM_FAULT_ codes OK? */
Carsten Otteceffc072005-06-23 22:05:25 -0700222
223 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -0700224 if (vmf->pgoff >= size)
225 return VM_FAULT_SIGBUS;
Carsten Otteceffc072005-06-23 22:05:25 -0700226
Nick Piggin54cb8822007-07-19 01:46:59 -0700227 page = mapping->a_ops->get_xip_page(mapping,
Nick Piggind0217ac2007-07-19 01:47:03 -0700228 vmf->pgoff*(PAGE_SIZE/512), 0);
Carsten Ottea76c0b92007-03-29 01:20:39 -0700229 if (!IS_ERR(page))
Nick Pigginb5810032005-10-29 18:16:12 -0700230 goto out;
Nick Piggind0217ac2007-07-19 01:47:03 -0700231 if (PTR_ERR(page) != -ENODATA)
232 return VM_FAULT_OOM;
Carsten Otteceffc072005-06-23 22:05:25 -0700233
234 /* sparse block */
235 if ((area->vm_flags & (VM_WRITE | VM_MAYWRITE)) &&
236 (area->vm_flags & (VM_SHARED| VM_MAYSHARE)) &&
237 (!(mapping->host->i_sb->s_flags & MS_RDONLY))) {
238 /* maybe shared writable, allocate new block */
Nick Piggin54cb8822007-07-19 01:46:59 -0700239 page = mapping->a_ops->get_xip_page(mapping,
Nick Piggind0217ac2007-07-19 01:47:03 -0700240 vmf->pgoff*(PAGE_SIZE/512), 1);
241 if (IS_ERR(page))
242 return VM_FAULT_SIGBUS;
Carsten Otteceffc072005-06-23 22:05:25 -0700243 /* unmap page at pgoff from all other vmas */
Nick Piggind0217ac2007-07-19 01:47:03 -0700244 __xip_unmap(mapping, vmf->pgoff);
Carsten Otteceffc072005-06-23 22:05:25 -0700245 } else {
Carsten Ottea76c0b92007-03-29 01:20:39 -0700246 /* not shared and writable, use xip_sparse_page() */
247 page = xip_sparse_page();
Nick Piggind0217ac2007-07-19 01:47:03 -0700248 if (!page)
249 return VM_FAULT_OOM;
Carsten Otteceffc072005-06-23 22:05:25 -0700250 }
251
Nick Pigginb5810032005-10-29 18:16:12 -0700252out:
253 page_cache_get(page);
Nick Piggind0217ac2007-07-19 01:47:03 -0700254 vmf->page = page;
255 return VM_FAULT_MINOR;
Carsten Otteceffc072005-06-23 22:05:25 -0700256}
257
258static struct vm_operations_struct xip_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -0700259 .fault = xip_file_fault,
Carsten Otteceffc072005-06-23 22:05:25 -0700260};
261
262int xip_file_mmap(struct file * file, struct vm_area_struct * vma)
263{
264 BUG_ON(!file->f_mapping->a_ops->get_xip_page);
265
266 file_accessed(file);
267 vma->vm_ops = &xip_file_vm_ops;
Nick Piggin54cb8822007-07-19 01:46:59 -0700268 vma->vm_flags |= VM_CAN_NONLINEAR;
Carsten Otteceffc072005-06-23 22:05:25 -0700269 return 0;
270}
271EXPORT_SYMBOL_GPL(xip_file_mmap);
272
273static ssize_t
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700274__xip_file_write(struct file *filp, const char __user *buf,
275 size_t count, loff_t pos, loff_t *ppos)
Carsten Otteceffc072005-06-23 22:05:25 -0700276{
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700277 struct address_space * mapping = filp->f_mapping;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700278 const struct address_space_operations *a_ops = mapping->a_ops;
Carsten Otteceffc072005-06-23 22:05:25 -0700279 struct inode *inode = mapping->host;
280 long status = 0;
281 struct page *page;
282 size_t bytes;
Carsten Otteceffc072005-06-23 22:05:25 -0700283 ssize_t written = 0;
284
285 BUG_ON(!mapping->a_ops->get_xip_page);
286
Carsten Otteceffc072005-06-23 22:05:25 -0700287 do {
288 unsigned long index;
289 unsigned long offset;
290 size_t copied;
291
292 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
293 index = pos >> PAGE_CACHE_SHIFT;
294 bytes = PAGE_CACHE_SIZE - offset;
295 if (bytes > count)
296 bytes = count;
297
298 /*
299 * Bring in the user page that we will copy from _first_.
300 * Otherwise there's a nasty deadlock on copying from the
301 * same page as we're writing to, without it being marked
302 * up-to-date.
303 */
304 fault_in_pages_readable(buf, bytes);
305
306 page = a_ops->get_xip_page(mapping,
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700307 index*(PAGE_SIZE/512), 0);
Carsten Otteceffc072005-06-23 22:05:25 -0700308 if (IS_ERR(page) && (PTR_ERR(page) == -ENODATA)) {
309 /* we allocate a new page unmap it */
310 page = a_ops->get_xip_page(mapping,
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700311 index*(PAGE_SIZE/512), 1);
Carsten Otteceffc072005-06-23 22:05:25 -0700312 if (!IS_ERR(page))
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700313 /* unmap page at pgoff from all other vmas */
314 __xip_unmap(mapping, index);
Carsten Otteceffc072005-06-23 22:05:25 -0700315 }
316
317 if (IS_ERR(page)) {
318 status = PTR_ERR(page);
319 break;
320 }
321
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700322 copied = filemap_copy_from_user(page, offset, buf, bytes);
Carsten Otteceffc072005-06-23 22:05:25 -0700323 flush_dcache_page(page);
324 if (likely(copied > 0)) {
325 status = copied;
326
327 if (status >= 0) {
328 written += status;
329 count -= status;
330 pos += status;
331 buf += status;
Carsten Otteceffc072005-06-23 22:05:25 -0700332 }
333 }
334 if (unlikely(copied != bytes))
335 if (status >= 0)
336 status = -EFAULT;
337 if (status < 0)
338 break;
339 } while (count);
340 *ppos = pos;
341 /*
342 * No need to use i_size_read() here, the i_size
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800343 * cannot change under us because we hold i_mutex.
Carsten Otteceffc072005-06-23 22:05:25 -0700344 */
345 if (pos > inode->i_size) {
346 i_size_write(inode, pos);
347 mark_inode_dirty(inode);
348 }
349
350 return written ? written : status;
351}
352
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700353ssize_t
354xip_file_write(struct file *filp, const char __user *buf, size_t len,
355 loff_t *ppos)
Carsten Otteceffc072005-06-23 22:05:25 -0700356{
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700357 struct address_space *mapping = filp->f_mapping;
358 struct inode *inode = mapping->host;
359 size_t count;
360 loff_t pos;
361 ssize_t ret;
Carsten Otteceffc072005-06-23 22:05:25 -0700362
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800363 mutex_lock(&inode->i_mutex);
Carsten Otteceffc072005-06-23 22:05:25 -0700364
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700365 if (!access_ok(VERIFY_READ, buf, len)) {
366 ret=-EFAULT;
367 goto out_up;
Carsten Otteceffc072005-06-23 22:05:25 -0700368 }
369
Carsten Otteceffc072005-06-23 22:05:25 -0700370 pos = *ppos;
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700371 count = len;
Carsten Otteceffc072005-06-23 22:05:25 -0700372
373 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
374
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700375 /* We can write back this queue in page reclaim */
376 current->backing_dev_info = mapping->backing_dev_info;
Carsten Otteceffc072005-06-23 22:05:25 -0700377
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700378 ret = generic_write_checks(filp, &pos, &count, S_ISBLK(inode->i_mode));
379 if (ret)
380 goto out_backing;
Carsten Otteceffc072005-06-23 22:05:25 -0700381 if (count == 0)
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700382 goto out_backing;
Carsten Otteceffc072005-06-23 22:05:25 -0700383
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800384 ret = remove_suid(filp->f_path.dentry);
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700385 if (ret)
386 goto out_backing;
Carsten Otteceffc072005-06-23 22:05:25 -0700387
Christoph Hellwig870f4812006-01-09 20:52:01 -0800388 file_update_time(filp);
Carsten Otteceffc072005-06-23 22:05:25 -0700389
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700390 ret = __xip_file_write (filp, buf, count, pos, ppos);
Carsten Otteceffc072005-06-23 22:05:25 -0700391
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700392 out_backing:
393 current->backing_dev_info = NULL;
394 out_up:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800395 mutex_unlock(&inode->i_mutex);
Carsten Otteceffc072005-06-23 22:05:25 -0700396 return ret;
397}
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700398EXPORT_SYMBOL_GPL(xip_file_write);
Carsten Otteceffc072005-06-23 22:05:25 -0700399
400/*
401 * truncate a page used for execute in place
402 * functionality is analog to block_truncate_page but does use get_xip_page
403 * to get the page instead of page cache
404 */
405int
406xip_truncate_page(struct address_space *mapping, loff_t from)
407{
408 pgoff_t index = from >> PAGE_CACHE_SHIFT;
409 unsigned offset = from & (PAGE_CACHE_SIZE-1);
410 unsigned blocksize;
411 unsigned length;
412 struct page *page;
Carsten Otteceffc072005-06-23 22:05:25 -0700413
414 BUG_ON(!mapping->a_ops->get_xip_page);
415
416 blocksize = 1 << mapping->host->i_blkbits;
417 length = offset & (blocksize - 1);
418
419 /* Block boundary? Nothing to do */
420 if (!length)
421 return 0;
422
423 length = blocksize - length;
424
425 page = mapping->a_ops->get_xip_page(mapping,
426 index*(PAGE_SIZE/512), 0);
Carsten Otteceffc072005-06-23 22:05:25 -0700427 if (!page)
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700428 return -ENOMEM;
Carsten Otteceffc072005-06-23 22:05:25 -0700429 if (unlikely(IS_ERR(page))) {
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700430 if (PTR_ERR(page) == -ENODATA)
Carsten Otteceffc072005-06-23 22:05:25 -0700431 /* Hole? No need to truncate */
432 return 0;
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700433 else
434 return PTR_ERR(page);
Carsten Otteafa597b2005-07-15 03:56:30 -0700435 }
Nate Diller01f27052007-05-09 02:35:07 -0700436 zero_user_page(page, offset, length, KM_USER0);
Carsten Otteeb6fe0c2005-06-23 22:05:28 -0700437 return 0;
Carsten Otteceffc072005-06-23 22:05:25 -0700438}
439EXPORT_SYMBOL_GPL(xip_truncate_page);