Linux Audio

Check our new training course

Embedded Linux Audio

Check our new training course
with Creative Commons CC-BY-SA
lecture materials

Bootlin logo

Elixir Cross Referencer

Loading...
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
/*
 *	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(0);
		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, vma);
			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(0);
	}

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;
	const 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_path.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);