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1 | /* | |
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> | |
16 | #include <linux/mmu_notifier.h> | |
17 | #include <linux/sched.h> | |
18 | #include <linux/seqlock.h> | |
19 | #include <linux/mutex.h> | |
20 | #include <asm/tlbflush.h> | |
21 | #include <asm/io.h> | |
22 | ||
23 | /* | |
24 | * We do use our own empty page to avoid interference with other users | |
25 | * of ZERO_PAGE(), such as /dev/zero | |
26 | */ | |
27 | static DEFINE_MUTEX(xip_sparse_mutex); | |
28 | static seqcount_t xip_sparse_seq = SEQCNT_ZERO; | |
29 | static struct page *__xip_sparse_page; | |
30 | ||
31 | /* called under xip_sparse_mutex */ | |
32 | static struct page *xip_sparse_page(void) | |
33 | { | |
34 | if (!__xip_sparse_page) { | |
35 | struct page *page = alloc_page(GFP_HIGHUSER | __GFP_ZERO); | |
36 | ||
37 | if (page) | |
38 | __xip_sparse_page = page; | |
39 | } | |
40 | return __xip_sparse_page; | |
41 | } | |
42 | ||
43 | /* | |
44 | * This is a file read routine for execute in place files, and uses | |
45 | * the mapping->a_ops->get_xip_mem() function for the actual low-level | |
46 | * stuff. | |
47 | * | |
48 | * Note the struct file* is not used at all. It may be NULL. | |
49 | */ | |
50 | static ssize_t | |
51 | do_xip_mapping_read(struct address_space *mapping, | |
52 | struct file_ra_state *_ra, | |
53 | struct file *filp, | |
54 | char __user *buf, | |
55 | size_t len, | |
56 | loff_t *ppos) | |
57 | { | |
58 | struct inode *inode = mapping->host; | |
59 | pgoff_t index, end_index; | |
60 | unsigned long offset; | |
61 | loff_t isize, pos; | |
62 | size_t copied = 0, error = 0; | |
63 | ||
64 | BUG_ON(!mapping->a_ops->get_xip_mem); | |
65 | ||
66 | pos = *ppos; | |
67 | index = pos >> PAGE_CACHE_SHIFT; | |
68 | offset = pos & ~PAGE_CACHE_MASK; | |
69 | ||
70 | isize = i_size_read(inode); | |
71 | if (!isize) | |
72 | goto out; | |
73 | ||
74 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
75 | do { | |
76 | unsigned long nr, left; | |
77 | void *xip_mem; | |
78 | unsigned long xip_pfn; | |
79 | int zero = 0; | |
80 | ||
81 | /* nr is the maximum number of bytes to copy from this page */ | |
82 | nr = PAGE_CACHE_SIZE; | |
83 | if (index >= end_index) { | |
84 | if (index > end_index) | |
85 | goto out; | |
86 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
87 | if (nr <= offset) { | |
88 | goto out; | |
89 | } | |
90 | } | |
91 | nr = nr - offset; | |
92 | if (nr > len - copied) | |
93 | nr = len - copied; | |
94 | ||
95 | error = mapping->a_ops->get_xip_mem(mapping, index, 0, | |
96 | &xip_mem, &xip_pfn); | |
97 | if (unlikely(error)) { | |
98 | if (error == -ENODATA) { | |
99 | /* sparse */ | |
100 | zero = 1; | |
101 | } else | |
102 | goto out; | |
103 | } | |
104 | ||
105 | /* If users can be writing to this page using arbitrary | |
106 | * virtual addresses, take care about potential aliasing | |
107 | * before reading the page on the kernel side. | |
108 | */ | |
109 | if (mapping_writably_mapped(mapping)) | |
110 | /* address based flush */ ; | |
111 | ||
112 | /* | |
113 | * Ok, we have the mem, so now we can copy it to user space... | |
114 | * | |
115 | * The actor routine returns how many bytes were actually used.. | |
116 | * NOTE! This may not be the same as how much of a user buffer | |
117 | * we filled up (we may be padding etc), so we can only update | |
118 | * "pos" here (the actor routine has to update the user buffer | |
119 | * pointers and the remaining count). | |
120 | */ | |
121 | if (!zero) | |
122 | left = __copy_to_user(buf+copied, xip_mem+offset, nr); | |
123 | else | |
124 | left = __clear_user(buf + copied, nr); | |
125 | ||
126 | if (left) { | |
127 | error = -EFAULT; | |
128 | goto out; | |
129 | } | |
130 | ||
131 | copied += (nr - left); | |
132 | offset += (nr - left); | |
133 | index += offset >> PAGE_CACHE_SHIFT; | |
134 | offset &= ~PAGE_CACHE_MASK; | |
135 | } while (copied < len); | |
136 | ||
137 | out: | |
138 | *ppos = pos + copied; | |
139 | if (filp) | |
140 | file_accessed(filp); | |
141 | ||
142 | return (copied ? copied : error); | |
143 | } | |
144 | ||
145 | ssize_t | |
146 | xip_file_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos) | |
147 | { | |
148 | if (!access_ok(VERIFY_WRITE, buf, len)) | |
149 | return -EFAULT; | |
150 | ||
151 | return do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp, | |
152 | buf, len, ppos); | |
153 | } | |
154 | EXPORT_SYMBOL_GPL(xip_file_read); | |
155 | ||
156 | /* | |
157 | * __xip_unmap is invoked from xip_unmap and | |
158 | * xip_write | |
159 | * | |
160 | * This function walks all vmas of the address_space and unmaps the | |
161 | * __xip_sparse_page when found at pgoff. | |
162 | */ | |
163 | static void | |
164 | __xip_unmap (struct address_space * mapping, | |
165 | unsigned long pgoff) | |
166 | { | |
167 | struct vm_area_struct *vma; | |
168 | struct mm_struct *mm; | |
169 | struct prio_tree_iter iter; | |
170 | unsigned long address; | |
171 | pte_t *pte; | |
172 | pte_t pteval; | |
173 | spinlock_t *ptl; | |
174 | struct page *page; | |
175 | unsigned count; | |
176 | int locked = 0; | |
177 | ||
178 | count = read_seqcount_begin(&xip_sparse_seq); | |
179 | ||
180 | page = __xip_sparse_page; | |
181 | if (!page) | |
182 | return; | |
183 | ||
184 | retry: | |
185 | spin_lock(&mapping->i_mmap_lock); | |
186 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
187 | mm = vma->vm_mm; | |
188 | address = vma->vm_start + | |
189 | ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
190 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
191 | pte = page_check_address(page, mm, address, &ptl, 1); | |
192 | if (pte) { | |
193 | /* Nuke the page table entry. */ | |
194 | flush_cache_page(vma, address, pte_pfn(*pte)); | |
195 | pteval = ptep_clear_flush_notify(vma, address, pte); | |
196 | page_remove_rmap(page); | |
197 | dec_mm_counter(mm, file_rss); | |
198 | BUG_ON(pte_dirty(pteval)); | |
199 | pte_unmap_unlock(pte, ptl); | |
200 | page_cache_release(page); | |
201 | } | |
202 | } | |
203 | spin_unlock(&mapping->i_mmap_lock); | |
204 | ||
205 | if (locked) { | |
206 | mutex_unlock(&xip_sparse_mutex); | |
207 | } else if (read_seqcount_retry(&xip_sparse_seq, count)) { | |
208 | mutex_lock(&xip_sparse_mutex); | |
209 | locked = 1; | |
210 | goto retry; | |
211 | } | |
212 | } | |
213 | ||
214 | /* | |
215 | * xip_fault() is invoked via the vma operations vector for a | |
216 | * mapped memory region to read in file data during a page fault. | |
217 | * | |
218 | * This function is derived from filemap_fault, but used for execute in place | |
219 | */ | |
220 | static int xip_file_fault(struct vm_area_struct *vma, struct vm_fault *vmf) | |
221 | { | |
222 | struct file *file = vma->vm_file; | |
223 | struct address_space *mapping = file->f_mapping; | |
224 | struct inode *inode = mapping->host; | |
225 | pgoff_t size; | |
226 | void *xip_mem; | |
227 | unsigned long xip_pfn; | |
228 | struct page *page; | |
229 | int error; | |
230 | ||
231 | /* XXX: are VM_FAULT_ codes OK? */ | |
232 | again: | |
233 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
234 | if (vmf->pgoff >= size) | |
235 | return VM_FAULT_SIGBUS; | |
236 | ||
237 | error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 0, | |
238 | &xip_mem, &xip_pfn); | |
239 | if (likely(!error)) | |
240 | goto found; | |
241 | if (error != -ENODATA) | |
242 | return VM_FAULT_OOM; | |
243 | ||
244 | /* sparse block */ | |
245 | if ((vma->vm_flags & (VM_WRITE | VM_MAYWRITE)) && | |
246 | (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) && | |
247 | (!(mapping->host->i_sb->s_flags & MS_RDONLY))) { | |
248 | int err; | |
249 | ||
250 | /* maybe shared writable, allocate new block */ | |
251 | mutex_lock(&xip_sparse_mutex); | |
252 | error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 1, | |
253 | &xip_mem, &xip_pfn); | |
254 | mutex_unlock(&xip_sparse_mutex); | |
255 | if (error) | |
256 | return VM_FAULT_SIGBUS; | |
257 | /* unmap sparse mappings at pgoff from all other vmas */ | |
258 | __xip_unmap(mapping, vmf->pgoff); | |
259 | ||
260 | found: | |
261 | err = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, | |
262 | xip_pfn); | |
263 | if (err == -ENOMEM) | |
264 | return VM_FAULT_OOM; | |
265 | BUG_ON(err); | |
266 | return VM_FAULT_NOPAGE; | |
267 | } else { | |
268 | int err, ret = VM_FAULT_OOM; | |
269 | ||
270 | mutex_lock(&xip_sparse_mutex); | |
271 | write_seqcount_begin(&xip_sparse_seq); | |
272 | error = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 0, | |
273 | &xip_mem, &xip_pfn); | |
274 | if (unlikely(!error)) { | |
275 | write_seqcount_end(&xip_sparse_seq); | |
276 | mutex_unlock(&xip_sparse_mutex); | |
277 | goto again; | |
278 | } | |
279 | if (error != -ENODATA) | |
280 | goto out; | |
281 | /* not shared and writable, use xip_sparse_page() */ | |
282 | page = xip_sparse_page(); | |
283 | if (!page) | |
284 | goto out; | |
285 | err = vm_insert_page(vma, (unsigned long)vmf->virtual_address, | |
286 | page); | |
287 | if (err == -ENOMEM) | |
288 | goto out; | |
289 | ||
290 | ret = VM_FAULT_NOPAGE; | |
291 | out: | |
292 | write_seqcount_end(&xip_sparse_seq); | |
293 | mutex_unlock(&xip_sparse_mutex); | |
294 | ||
295 | return ret; | |
296 | } | |
297 | } | |
298 | ||
299 | static const struct vm_operations_struct xip_file_vm_ops = { | |
300 | .fault = xip_file_fault, | |
301 | }; | |
302 | ||
303 | int xip_file_mmap(struct file * file, struct vm_area_struct * vma) | |
304 | { | |
305 | BUG_ON(!file->f_mapping->a_ops->get_xip_mem); | |
306 | ||
307 | file_accessed(file); | |
308 | vma->vm_ops = &xip_file_vm_ops; | |
309 | vma->vm_flags |= VM_CAN_NONLINEAR | VM_MIXEDMAP; | |
310 | return 0; | |
311 | } | |
312 | EXPORT_SYMBOL_GPL(xip_file_mmap); | |
313 | ||
314 | static ssize_t | |
315 | __xip_file_write(struct file *filp, const char __user *buf, | |
316 | size_t count, loff_t pos, loff_t *ppos) | |
317 | { | |
318 | struct address_space * mapping = filp->f_mapping; | |
319 | const struct address_space_operations *a_ops = mapping->a_ops; | |
320 | struct inode *inode = mapping->host; | |
321 | long status = 0; | |
322 | size_t bytes; | |
323 | ssize_t written = 0; | |
324 | ||
325 | BUG_ON(!mapping->a_ops->get_xip_mem); | |
326 | ||
327 | do { | |
328 | unsigned long index; | |
329 | unsigned long offset; | |
330 | size_t copied; | |
331 | void *xip_mem; | |
332 | unsigned long xip_pfn; | |
333 | ||
334 | offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ | |
335 | index = pos >> PAGE_CACHE_SHIFT; | |
336 | bytes = PAGE_CACHE_SIZE - offset; | |
337 | if (bytes > count) | |
338 | bytes = count; | |
339 | ||
340 | status = a_ops->get_xip_mem(mapping, index, 0, | |
341 | &xip_mem, &xip_pfn); | |
342 | if (status == -ENODATA) { | |
343 | /* we allocate a new page unmap it */ | |
344 | mutex_lock(&xip_sparse_mutex); | |
345 | status = a_ops->get_xip_mem(mapping, index, 1, | |
346 | &xip_mem, &xip_pfn); | |
347 | mutex_unlock(&xip_sparse_mutex); | |
348 | if (!status) | |
349 | /* unmap page at pgoff from all other vmas */ | |
350 | __xip_unmap(mapping, index); | |
351 | } | |
352 | ||
353 | if (status) | |
354 | break; | |
355 | ||
356 | copied = bytes - | |
357 | __copy_from_user_nocache(xip_mem + offset, buf, bytes); | |
358 | ||
359 | if (likely(copied > 0)) { | |
360 | status = copied; | |
361 | ||
362 | if (status >= 0) { | |
363 | written += status; | |
364 | count -= status; | |
365 | pos += status; | |
366 | buf += status; | |
367 | } | |
368 | } | |
369 | if (unlikely(copied != bytes)) | |
370 | if (status >= 0) | |
371 | status = -EFAULT; | |
372 | if (status < 0) | |
373 | break; | |
374 | } while (count); | |
375 | *ppos = pos; | |
376 | /* | |
377 | * No need to use i_size_read() here, the i_size | |
378 | * cannot change under us because we hold i_mutex. | |
379 | */ | |
380 | if (pos > inode->i_size) { | |
381 | i_size_write(inode, pos); | |
382 | mark_inode_dirty(inode); | |
383 | } | |
384 | ||
385 | return written ? written : status; | |
386 | } | |
387 | ||
388 | ssize_t | |
389 | xip_file_write(struct file *filp, const char __user *buf, size_t len, | |
390 | loff_t *ppos) | |
391 | { | |
392 | struct address_space *mapping = filp->f_mapping; | |
393 | struct inode *inode = mapping->host; | |
394 | size_t count; | |
395 | loff_t pos; | |
396 | ssize_t ret; | |
397 | ||
398 | mutex_lock(&inode->i_mutex); | |
399 | ||
400 | if (!access_ok(VERIFY_READ, buf, len)) { | |
401 | ret=-EFAULT; | |
402 | goto out_up; | |
403 | } | |
404 | ||
405 | pos = *ppos; | |
406 | count = len; | |
407 | ||
408 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
409 | ||
410 | /* We can write back this queue in page reclaim */ | |
411 | current->backing_dev_info = mapping->backing_dev_info; | |
412 | ||
413 | ret = generic_write_checks(filp, &pos, &count, S_ISBLK(inode->i_mode)); | |
414 | if (ret) | |
415 | goto out_backing; | |
416 | if (count == 0) | |
417 | goto out_backing; | |
418 | ||
419 | ret = file_remove_suid(filp); | |
420 | if (ret) | |
421 | goto out_backing; | |
422 | ||
423 | file_update_time(filp); | |
424 | ||
425 | ret = __xip_file_write (filp, buf, count, pos, ppos); | |
426 | ||
427 | out_backing: | |
428 | current->backing_dev_info = NULL; | |
429 | out_up: | |
430 | mutex_unlock(&inode->i_mutex); | |
431 | return ret; | |
432 | } | |
433 | EXPORT_SYMBOL_GPL(xip_file_write); | |
434 | ||
435 | /* | |
436 | * truncate a page used for execute in place | |
437 | * functionality is analog to block_truncate_page but does use get_xip_mem | |
438 | * to get the page instead of page cache | |
439 | */ | |
440 | int | |
441 | xip_truncate_page(struct address_space *mapping, loff_t from) | |
442 | { | |
443 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
444 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
445 | unsigned blocksize; | |
446 | unsigned length; | |
447 | void *xip_mem; | |
448 | unsigned long xip_pfn; | |
449 | int err; | |
450 | ||
451 | BUG_ON(!mapping->a_ops->get_xip_mem); | |
452 | ||
453 | blocksize = 1 << mapping->host->i_blkbits; | |
454 | length = offset & (blocksize - 1); | |
455 | ||
456 | /* Block boundary? Nothing to do */ | |
457 | if (!length) | |
458 | return 0; | |
459 | ||
460 | length = blocksize - length; | |
461 | ||
462 | err = mapping->a_ops->get_xip_mem(mapping, index, 0, | |
463 | &xip_mem, &xip_pfn); | |
464 | if (unlikely(err)) { | |
465 | if (err == -ENODATA) | |
466 | /* Hole? No need to truncate */ | |
467 | return 0; | |
468 | else | |
469 | return err; | |
470 | } | |
471 | memset(xip_mem + offset, 0, length); | |
472 | return 0; | |
473 | } | |
474 | EXPORT_SYMBOL_GPL(xip_truncate_page); |