blob: b891a129b275d56985a436bb30bf5486a5b81ec7 [file] [log] [blame]
Dan Williamsab68f262016-05-18 09:15:08 -07001/*
2 * Copyright(c) 2016 Intel Corporation. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of version 2 of the GNU General Public License as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 */
13#include <linux/pagemap.h>
14#include <linux/module.h>
15#include <linux/device.h>
16#include <linux/pfn_t.h>
17#include <linux/slab.h>
18#include <linux/dax.h>
19#include <linux/fs.h>
20#include <linux/mm.h>
21
22static int dax_major;
23static struct class *dax_class;
24static DEFINE_IDA(dax_minor_ida);
25
26/**
27 * struct dax_region - mapping infrastructure for dax devices
28 * @id: kernel-wide unique region for a memory range
29 * @base: linear address corresponding to @res
30 * @kref: to pin while other agents have a need to do lookups
31 * @dev: parent device backing this region
32 * @align: allocation and mapping alignment for child dax devices
33 * @res: physical address range of the region
34 * @pfn_flags: identify whether the pfns are paged back or not
35 */
36struct dax_region {
37 int id;
38 struct ida ida;
39 void *base;
40 struct kref kref;
41 struct device *dev;
42 unsigned int align;
43 struct resource res;
44 unsigned long pfn_flags;
45};
46
47/**
48 * struct dax_dev - subdivision of a dax region
49 * @region - parent region
50 * @dev - device backing the character device
51 * @kref - enable this data to be tracked in filp->private_data
Dan Williamsdee41072016-05-14 12:20:44 -070052 * @alive - !alive + rcu grace period == no new mappings can be established
Dan Williamsab68f262016-05-18 09:15:08 -070053 * @id - child id in the region
54 * @num_resources - number of physical address extents in this device
55 * @res - array of physical address ranges
56 */
57struct dax_dev {
58 struct dax_region *region;
59 struct device *dev;
60 struct kref kref;
Dan Williamsdee41072016-05-14 12:20:44 -070061 bool alive;
Dan Williamsab68f262016-05-18 09:15:08 -070062 int id;
63 int num_resources;
64 struct resource res[0];
65};
66
67static void dax_region_free(struct kref *kref)
68{
69 struct dax_region *dax_region;
70
71 dax_region = container_of(kref, struct dax_region, kref);
72 kfree(dax_region);
73}
74
75void dax_region_put(struct dax_region *dax_region)
76{
77 kref_put(&dax_region->kref, dax_region_free);
78}
79EXPORT_SYMBOL_GPL(dax_region_put);
80
81static void dax_dev_free(struct kref *kref)
82{
83 struct dax_dev *dax_dev;
84
85 dax_dev = container_of(kref, struct dax_dev, kref);
86 dax_region_put(dax_dev->region);
87 kfree(dax_dev);
88}
89
90static void dax_dev_put(struct dax_dev *dax_dev)
91{
92 kref_put(&dax_dev->kref, dax_dev_free);
93}
94
95struct dax_region *alloc_dax_region(struct device *parent, int region_id,
96 struct resource *res, unsigned int align, void *addr,
97 unsigned long pfn_flags)
98{
99 struct dax_region *dax_region;
100
101 dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
102
103 if (!dax_region)
104 return NULL;
105
106 memcpy(&dax_region->res, res, sizeof(*res));
107 dax_region->pfn_flags = pfn_flags;
108 kref_init(&dax_region->kref);
109 dax_region->id = region_id;
110 ida_init(&dax_region->ida);
111 dax_region->align = align;
112 dax_region->dev = parent;
113 dax_region->base = addr;
114
115 return dax_region;
116}
117EXPORT_SYMBOL_GPL(alloc_dax_region);
118
119static ssize_t size_show(struct device *dev,
120 struct device_attribute *attr, char *buf)
121{
122 struct dax_dev *dax_dev = dev_get_drvdata(dev);
123 unsigned long long size = 0;
124 int i;
125
126 for (i = 0; i < dax_dev->num_resources; i++)
127 size += resource_size(&dax_dev->res[i]);
128
129 return sprintf(buf, "%llu\n", size);
130}
131static DEVICE_ATTR_RO(size);
132
133static struct attribute *dax_device_attributes[] = {
134 &dev_attr_size.attr,
135 NULL,
136};
137
138static const struct attribute_group dax_device_attribute_group = {
139 .attrs = dax_device_attributes,
140};
141
142static const struct attribute_group *dax_attribute_groups[] = {
143 &dax_device_attribute_group,
144 NULL,
145};
146
147static void unregister_dax_dev(void *_dev)
148{
149 struct device *dev = _dev;
150 struct dax_dev *dax_dev = dev_get_drvdata(dev);
151 struct dax_region *dax_region = dax_dev->region;
152
153 dev_dbg(dev, "%s\n", __func__);
154
Dan Williamsdee41072016-05-14 12:20:44 -0700155 /*
156 * Note, rcu is not protecting the liveness of dax_dev, rcu is
157 * ensuring that any fault handlers that might have seen
158 * dax_dev->alive == true, have completed. Any fault handlers
159 * that start after synchronize_rcu() has started will abort
160 * upon seeing dax_dev->alive == false.
161 */
162 dax_dev->alive = false;
163 synchronize_rcu();
164
Dan Williamsab68f262016-05-18 09:15:08 -0700165 get_device(dev);
166 device_unregister(dev);
167 ida_simple_remove(&dax_region->ida, dax_dev->id);
168 ida_simple_remove(&dax_minor_ida, MINOR(dev->devt));
169 put_device(dev);
170 dax_dev_put(dax_dev);
171}
172
173int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res,
174 int count)
175{
176 struct device *parent = dax_region->dev;
177 struct dax_dev *dax_dev;
178 struct device *dev;
179 int rc, minor;
180 dev_t dev_t;
181
182 dax_dev = kzalloc(sizeof(*dax_dev) + sizeof(*res) * count, GFP_KERNEL);
183 if (!dax_dev)
184 return -ENOMEM;
185 memcpy(dax_dev->res, res, sizeof(*res) * count);
186 dax_dev->num_resources = count;
187 kref_init(&dax_dev->kref);
Dan Williamsdee41072016-05-14 12:20:44 -0700188 dax_dev->alive = true;
Dan Williamsab68f262016-05-18 09:15:08 -0700189 dax_dev->region = dax_region;
190 kref_get(&dax_region->kref);
191
192 dax_dev->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
193 if (dax_dev->id < 0) {
194 rc = dax_dev->id;
195 goto err_id;
196 }
197
198 minor = ida_simple_get(&dax_minor_ida, 0, 0, GFP_KERNEL);
199 if (minor < 0) {
200 rc = minor;
201 goto err_minor;
202 }
203
204 dev_t = MKDEV(dax_major, minor);
205 dev = device_create_with_groups(dax_class, parent, dev_t, dax_dev,
206 dax_attribute_groups, "dax%d.%d", dax_region->id,
207 dax_dev->id);
208 if (IS_ERR(dev)) {
209 rc = PTR_ERR(dev);
210 goto err_create;
211 }
212 dax_dev->dev = dev;
213
214 rc = devm_add_action(dax_region->dev, unregister_dax_dev, dev);
215 if (rc) {
216 unregister_dax_dev(dev);
217 return rc;
218 }
219
220 return 0;
221
222 err_create:
223 ida_simple_remove(&dax_minor_ida, minor);
224 err_minor:
225 ida_simple_remove(&dax_region->ida, dax_dev->id);
226 err_id:
227 dax_dev_put(dax_dev);
228
229 return rc;
230}
231EXPORT_SYMBOL_GPL(devm_create_dax_dev);
232
Dan Williamsdee41072016-05-14 12:20:44 -0700233/* return an unmapped area aligned to the dax region specified alignment */
234static unsigned long dax_dev_get_unmapped_area(struct file *filp,
235 unsigned long addr, unsigned long len, unsigned long pgoff,
236 unsigned long flags)
237{
238 unsigned long off, off_end, off_align, len_align, addr_align, align;
239 struct dax_dev *dax_dev = filp ? filp->private_data : NULL;
240 struct dax_region *dax_region;
241
242 if (!dax_dev || addr)
243 goto out;
244
245 dax_region = dax_dev->region;
246 align = dax_region->align;
247 off = pgoff << PAGE_SHIFT;
248 off_end = off + len;
249 off_align = round_up(off, align);
250
251 if ((off_end <= off_align) || ((off_end - off_align) < align))
252 goto out;
253
254 len_align = len + align;
255 if ((off + len_align) < off)
256 goto out;
257
258 addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
259 pgoff, flags);
260 if (!IS_ERR_VALUE(addr_align)) {
261 addr_align += (off - addr_align) & (align - 1);
262 return addr_align;
263 }
264 out:
265 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
266}
267
268static int __match_devt(struct device *dev, const void *data)
269{
270 const dev_t *devt = data;
271
272 return dev->devt == *devt;
273}
274
275static struct device *dax_dev_find(dev_t dev_t)
276{
277 return class_find_device(dax_class, NULL, &dev_t, __match_devt);
278}
279
280static int dax_dev_open(struct inode *inode, struct file *filp)
281{
282 struct dax_dev *dax_dev = NULL;
283 struct device *dev;
284
285 dev = dax_dev_find(inode->i_rdev);
286 if (!dev)
287 return -ENXIO;
288
289 device_lock(dev);
290 dax_dev = dev_get_drvdata(dev);
291 if (dax_dev) {
292 dev_dbg(dev, "%s\n", __func__);
293 filp->private_data = dax_dev;
294 kref_get(&dax_dev->kref);
295 inode->i_flags = S_DAX;
296 }
297 device_unlock(dev);
298
299 if (!dax_dev) {
300 put_device(dev);
301 return -ENXIO;
302 }
303 return 0;
304}
305
306static int dax_dev_release(struct inode *inode, struct file *filp)
307{
308 struct dax_dev *dax_dev = filp->private_data;
309 struct device *dev = dax_dev->dev;
310
311 dev_dbg(dax_dev->dev, "%s\n", __func__);
312 dax_dev_put(dax_dev);
313 put_device(dev);
314
315 return 0;
316}
317
318static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma,
319 const char *func)
320{
321 struct dax_region *dax_region = dax_dev->region;
322 struct device *dev = dax_dev->dev;
323 unsigned long mask;
324
325 if (!dax_dev->alive)
326 return -ENXIO;
327
328 /* prevent private / writable mappings from being established */
329 if ((vma->vm_flags & (VM_NORESERVE|VM_SHARED|VM_WRITE)) == VM_WRITE) {
330 dev_info(dev, "%s: %s: fail, attempted private mapping\n",
331 current->comm, func);
332 return -EINVAL;
333 }
334
335 mask = dax_region->align - 1;
336 if (vma->vm_start & mask || vma->vm_end & mask) {
337 dev_info(dev, "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
338 current->comm, func, vma->vm_start, vma->vm_end,
339 mask);
340 return -EINVAL;
341 }
342
343 if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
344 && (vma->vm_flags & VM_DONTCOPY) == 0) {
345 dev_info(dev, "%s: %s: fail, dax range requires MADV_DONTFORK\n",
346 current->comm, func);
347 return -EINVAL;
348 }
349
350 if (!vma_is_dax(vma)) {
351 dev_info(dev, "%s: %s: fail, vma is not DAX capable\n",
352 current->comm, func);
353 return -EINVAL;
354 }
355
356 return 0;
357}
358
359static phys_addr_t pgoff_to_phys(struct dax_dev *dax_dev, pgoff_t pgoff,
360 unsigned long size)
361{
362 struct resource *res;
363 phys_addr_t phys;
364 int i;
365
366 for (i = 0; i < dax_dev->num_resources; i++) {
367 res = &dax_dev->res[i];
368 phys = pgoff * PAGE_SIZE + res->start;
369 if (phys >= res->start && phys <= res->end)
370 break;
371 pgoff -= PHYS_PFN(resource_size(res));
372 }
373
374 if (i < dax_dev->num_resources) {
375 res = &dax_dev->res[i];
376 if (phys + size - 1 <= res->end)
377 return phys;
378 }
379
380 return -1;
381}
382
383static int __dax_dev_fault(struct dax_dev *dax_dev, struct vm_area_struct *vma,
384 struct vm_fault *vmf)
385{
386 unsigned long vaddr = (unsigned long) vmf->virtual_address;
387 struct device *dev = dax_dev->dev;
388 struct dax_region *dax_region;
389 int rc = VM_FAULT_SIGBUS;
390 phys_addr_t phys;
391 pfn_t pfn;
392
393 if (check_vma(dax_dev, vma, __func__))
394 return VM_FAULT_SIGBUS;
395
396 dax_region = dax_dev->region;
397 if (dax_region->align > PAGE_SIZE) {
398 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
399 return VM_FAULT_SIGBUS;
400 }
401
402 phys = pgoff_to_phys(dax_dev, vmf->pgoff, PAGE_SIZE);
403 if (phys == -1) {
404 dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
405 vmf->pgoff);
406 return VM_FAULT_SIGBUS;
407 }
408
409 pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
410
411 rc = vm_insert_mixed(vma, vaddr, pfn);
412
413 if (rc == -ENOMEM)
414 return VM_FAULT_OOM;
415 if (rc < 0 && rc != -EBUSY)
416 return VM_FAULT_SIGBUS;
417
418 return VM_FAULT_NOPAGE;
419}
420
421static int dax_dev_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
422{
423 int rc;
424 struct file *filp = vma->vm_file;
425 struct dax_dev *dax_dev = filp->private_data;
426
427 dev_dbg(dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
428 current->comm, (vmf->flags & FAULT_FLAG_WRITE)
429 ? "write" : "read", vma->vm_start, vma->vm_end);
430 rcu_read_lock();
431 rc = __dax_dev_fault(dax_dev, vma, vmf);
432 rcu_read_unlock();
433
434 return rc;
435}
436
437static int __dax_dev_pmd_fault(struct dax_dev *dax_dev,
438 struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd,
439 unsigned int flags)
440{
441 unsigned long pmd_addr = addr & PMD_MASK;
442 struct device *dev = dax_dev->dev;
443 struct dax_region *dax_region;
444 phys_addr_t phys;
445 pgoff_t pgoff;
446 pfn_t pfn;
447
448 if (check_vma(dax_dev, vma, __func__))
449 return VM_FAULT_SIGBUS;
450
451 dax_region = dax_dev->region;
452 if (dax_region->align > PMD_SIZE) {
453 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
454 return VM_FAULT_SIGBUS;
455 }
456
457 /* dax pmd mappings require pfn_t_devmap() */
458 if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
459 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
460 return VM_FAULT_SIGBUS;
461 }
462
463 pgoff = linear_page_index(vma, pmd_addr);
464 phys = pgoff_to_phys(dax_dev, pgoff, PAGE_SIZE);
465 if (phys == -1) {
466 dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
467 pgoff);
468 return VM_FAULT_SIGBUS;
469 }
470
471 pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
472
473 return vmf_insert_pfn_pmd(vma, addr, pmd, pfn,
474 flags & FAULT_FLAG_WRITE);
475}
476
477static int dax_dev_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
478 pmd_t *pmd, unsigned int flags)
479{
480 int rc;
481 struct file *filp = vma->vm_file;
482 struct dax_dev *dax_dev = filp->private_data;
483
484 dev_dbg(dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
485 current->comm, (flags & FAULT_FLAG_WRITE)
486 ? "write" : "read", vma->vm_start, vma->vm_end);
487
488 rcu_read_lock();
489 rc = __dax_dev_pmd_fault(dax_dev, vma, addr, pmd, flags);
490 rcu_read_unlock();
491
492 return rc;
493}
494
495static void dax_dev_vm_open(struct vm_area_struct *vma)
496{
497 struct file *filp = vma->vm_file;
498 struct dax_dev *dax_dev = filp->private_data;
499
500 dev_dbg(dax_dev->dev, "%s\n", __func__);
501 kref_get(&dax_dev->kref);
502}
503
504static void dax_dev_vm_close(struct vm_area_struct *vma)
505{
506 struct file *filp = vma->vm_file;
507 struct dax_dev *dax_dev = filp->private_data;
508
509 dev_dbg(dax_dev->dev, "%s\n", __func__);
510 dax_dev_put(dax_dev);
511}
512
513static const struct vm_operations_struct dax_dev_vm_ops = {
514 .fault = dax_dev_fault,
515 .pmd_fault = dax_dev_pmd_fault,
516 .open = dax_dev_vm_open,
517 .close = dax_dev_vm_close,
518};
519
520static int dax_dev_mmap(struct file *filp, struct vm_area_struct *vma)
521{
522 struct dax_dev *dax_dev = filp->private_data;
523 int rc;
524
525 dev_dbg(dax_dev->dev, "%s\n", __func__);
526
527 rc = check_vma(dax_dev, vma, __func__);
528 if (rc)
529 return rc;
530
531 kref_get(&dax_dev->kref);
532 vma->vm_ops = &dax_dev_vm_ops;
533 vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
534 return 0;
535
536}
537
Dan Williamsab68f262016-05-18 09:15:08 -0700538static const struct file_operations dax_fops = {
539 .llseek = noop_llseek,
540 .owner = THIS_MODULE,
Dan Williamsdee41072016-05-14 12:20:44 -0700541 .open = dax_dev_open,
542 .release = dax_dev_release,
543 .get_unmapped_area = dax_dev_get_unmapped_area,
544 .mmap = dax_dev_mmap,
Dan Williamsab68f262016-05-18 09:15:08 -0700545};
546
547static int __init dax_init(void)
548{
549 int rc;
550
551 rc = register_chrdev(0, "dax", &dax_fops);
552 if (rc < 0)
553 return rc;
554 dax_major = rc;
555
556 dax_class = class_create(THIS_MODULE, "dax");
557 if (IS_ERR(dax_class)) {
558 unregister_chrdev(dax_major, "dax");
559 return PTR_ERR(dax_class);
560 }
561
562 return 0;
563}
564
565static void __exit dax_exit(void)
566{
567 class_destroy(dax_class);
568 unregister_chrdev(dax_major, "dax");
569 ida_destroy(&dax_minor_ida);
570}
571
572MODULE_AUTHOR("Intel Corporation");
573MODULE_LICENSE("GPL v2");
574subsys_initcall(dax_init);
575module_exit(dax_exit);