blob: 29f600f2c447159e84b17bc43bdcd66ca8bbcc7b [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
Sajjan, Vikas Cd1c8e0c2016-07-05 11:20:07 +0530214 rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_dev, dev);
215 if (rc)
Dan Williamsab68f262016-05-18 09:15:08 -0700216 return rc;
Dan Williamsab68f262016-05-18 09:15:08 -0700217
218 return 0;
219
220 err_create:
221 ida_simple_remove(&dax_minor_ida, minor);
222 err_minor:
223 ida_simple_remove(&dax_region->ida, dax_dev->id);
224 err_id:
225 dax_dev_put(dax_dev);
226
227 return rc;
228}
229EXPORT_SYMBOL_GPL(devm_create_dax_dev);
230
Dan Williamsdee41072016-05-14 12:20:44 -0700231/* return an unmapped area aligned to the dax region specified alignment */
232static unsigned long dax_dev_get_unmapped_area(struct file *filp,
233 unsigned long addr, unsigned long len, unsigned long pgoff,
234 unsigned long flags)
235{
236 unsigned long off, off_end, off_align, len_align, addr_align, align;
237 struct dax_dev *dax_dev = filp ? filp->private_data : NULL;
238 struct dax_region *dax_region;
239
240 if (!dax_dev || addr)
241 goto out;
242
243 dax_region = dax_dev->region;
244 align = dax_region->align;
245 off = pgoff << PAGE_SHIFT;
246 off_end = off + len;
247 off_align = round_up(off, align);
248
249 if ((off_end <= off_align) || ((off_end - off_align) < align))
250 goto out;
251
252 len_align = len + align;
253 if ((off + len_align) < off)
254 goto out;
255
256 addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
257 pgoff, flags);
258 if (!IS_ERR_VALUE(addr_align)) {
259 addr_align += (off - addr_align) & (align - 1);
260 return addr_align;
261 }
262 out:
263 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
264}
265
266static int __match_devt(struct device *dev, const void *data)
267{
268 const dev_t *devt = data;
269
270 return dev->devt == *devt;
271}
272
273static struct device *dax_dev_find(dev_t dev_t)
274{
275 return class_find_device(dax_class, NULL, &dev_t, __match_devt);
276}
277
278static int dax_dev_open(struct inode *inode, struct file *filp)
279{
280 struct dax_dev *dax_dev = NULL;
281 struct device *dev;
282
283 dev = dax_dev_find(inode->i_rdev);
284 if (!dev)
285 return -ENXIO;
286
287 device_lock(dev);
288 dax_dev = dev_get_drvdata(dev);
289 if (dax_dev) {
290 dev_dbg(dev, "%s\n", __func__);
291 filp->private_data = dax_dev;
292 kref_get(&dax_dev->kref);
293 inode->i_flags = S_DAX;
294 }
295 device_unlock(dev);
296
297 if (!dax_dev) {
298 put_device(dev);
299 return -ENXIO;
300 }
301 return 0;
302}
303
304static int dax_dev_release(struct inode *inode, struct file *filp)
305{
306 struct dax_dev *dax_dev = filp->private_data;
307 struct device *dev = dax_dev->dev;
308
309 dev_dbg(dax_dev->dev, "%s\n", __func__);
310 dax_dev_put(dax_dev);
311 put_device(dev);
312
313 return 0;
314}
315
316static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma,
317 const char *func)
318{
319 struct dax_region *dax_region = dax_dev->region;
320 struct device *dev = dax_dev->dev;
321 unsigned long mask;
322
323 if (!dax_dev->alive)
324 return -ENXIO;
325
326 /* prevent private / writable mappings from being established */
327 if ((vma->vm_flags & (VM_NORESERVE|VM_SHARED|VM_WRITE)) == VM_WRITE) {
328 dev_info(dev, "%s: %s: fail, attempted private mapping\n",
329 current->comm, func);
330 return -EINVAL;
331 }
332
333 mask = dax_region->align - 1;
334 if (vma->vm_start & mask || vma->vm_end & mask) {
335 dev_info(dev, "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
336 current->comm, func, vma->vm_start, vma->vm_end,
337 mask);
338 return -EINVAL;
339 }
340
341 if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
342 && (vma->vm_flags & VM_DONTCOPY) == 0) {
343 dev_info(dev, "%s: %s: fail, dax range requires MADV_DONTFORK\n",
344 current->comm, func);
345 return -EINVAL;
346 }
347
348 if (!vma_is_dax(vma)) {
349 dev_info(dev, "%s: %s: fail, vma is not DAX capable\n",
350 current->comm, func);
351 return -EINVAL;
352 }
353
354 return 0;
355}
356
357static phys_addr_t pgoff_to_phys(struct dax_dev *dax_dev, pgoff_t pgoff,
358 unsigned long size)
359{
360 struct resource *res;
361 phys_addr_t phys;
362 int i;
363
364 for (i = 0; i < dax_dev->num_resources; i++) {
365 res = &dax_dev->res[i];
366 phys = pgoff * PAGE_SIZE + res->start;
367 if (phys >= res->start && phys <= res->end)
368 break;
369 pgoff -= PHYS_PFN(resource_size(res));
370 }
371
372 if (i < dax_dev->num_resources) {
373 res = &dax_dev->res[i];
374 if (phys + size - 1 <= res->end)
375 return phys;
376 }
377
378 return -1;
379}
380
381static int __dax_dev_fault(struct dax_dev *dax_dev, struct vm_area_struct *vma,
382 struct vm_fault *vmf)
383{
384 unsigned long vaddr = (unsigned long) vmf->virtual_address;
385 struct device *dev = dax_dev->dev;
386 struct dax_region *dax_region;
387 int rc = VM_FAULT_SIGBUS;
388 phys_addr_t phys;
389 pfn_t pfn;
390
391 if (check_vma(dax_dev, vma, __func__))
392 return VM_FAULT_SIGBUS;
393
394 dax_region = dax_dev->region;
395 if (dax_region->align > PAGE_SIZE) {
396 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
397 return VM_FAULT_SIGBUS;
398 }
399
400 phys = pgoff_to_phys(dax_dev, vmf->pgoff, PAGE_SIZE);
401 if (phys == -1) {
402 dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
403 vmf->pgoff);
404 return VM_FAULT_SIGBUS;
405 }
406
407 pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
408
409 rc = vm_insert_mixed(vma, vaddr, pfn);
410
411 if (rc == -ENOMEM)
412 return VM_FAULT_OOM;
413 if (rc < 0 && rc != -EBUSY)
414 return VM_FAULT_SIGBUS;
415
416 return VM_FAULT_NOPAGE;
417}
418
419static int dax_dev_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
420{
421 int rc;
422 struct file *filp = vma->vm_file;
423 struct dax_dev *dax_dev = filp->private_data;
424
425 dev_dbg(dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
426 current->comm, (vmf->flags & FAULT_FLAG_WRITE)
427 ? "write" : "read", vma->vm_start, vma->vm_end);
428 rcu_read_lock();
429 rc = __dax_dev_fault(dax_dev, vma, vmf);
430 rcu_read_unlock();
431
432 return rc;
433}
434
435static int __dax_dev_pmd_fault(struct dax_dev *dax_dev,
436 struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd,
437 unsigned int flags)
438{
439 unsigned long pmd_addr = addr & PMD_MASK;
440 struct device *dev = dax_dev->dev;
441 struct dax_region *dax_region;
442 phys_addr_t phys;
443 pgoff_t pgoff;
444 pfn_t pfn;
445
446 if (check_vma(dax_dev, vma, __func__))
447 return VM_FAULT_SIGBUS;
448
449 dax_region = dax_dev->region;
450 if (dax_region->align > PMD_SIZE) {
451 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
452 return VM_FAULT_SIGBUS;
453 }
454
455 /* dax pmd mappings require pfn_t_devmap() */
456 if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
457 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
458 return VM_FAULT_SIGBUS;
459 }
460
461 pgoff = linear_page_index(vma, pmd_addr);
Dan Williams4c3cb6e2016-09-03 10:36:00 -0700462 phys = pgoff_to_phys(dax_dev, pgoff, PMD_SIZE);
Dan Williamsdee41072016-05-14 12:20:44 -0700463 if (phys == -1) {
464 dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
465 pgoff);
466 return VM_FAULT_SIGBUS;
467 }
468
469 pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
470
471 return vmf_insert_pfn_pmd(vma, addr, pmd, pfn,
472 flags & FAULT_FLAG_WRITE);
473}
474
475static int dax_dev_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
476 pmd_t *pmd, unsigned int flags)
477{
478 int rc;
479 struct file *filp = vma->vm_file;
480 struct dax_dev *dax_dev = filp->private_data;
481
482 dev_dbg(dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
483 current->comm, (flags & FAULT_FLAG_WRITE)
484 ? "write" : "read", vma->vm_start, vma->vm_end);
485
486 rcu_read_lock();
487 rc = __dax_dev_pmd_fault(dax_dev, vma, addr, pmd, flags);
488 rcu_read_unlock();
489
490 return rc;
491}
492
493static void dax_dev_vm_open(struct vm_area_struct *vma)
494{
495 struct file *filp = vma->vm_file;
496 struct dax_dev *dax_dev = filp->private_data;
497
498 dev_dbg(dax_dev->dev, "%s\n", __func__);
499 kref_get(&dax_dev->kref);
500}
501
502static void dax_dev_vm_close(struct vm_area_struct *vma)
503{
504 struct file *filp = vma->vm_file;
505 struct dax_dev *dax_dev = filp->private_data;
506
507 dev_dbg(dax_dev->dev, "%s\n", __func__);
508 dax_dev_put(dax_dev);
509}
510
511static const struct vm_operations_struct dax_dev_vm_ops = {
512 .fault = dax_dev_fault,
513 .pmd_fault = dax_dev_pmd_fault,
514 .open = dax_dev_vm_open,
515 .close = dax_dev_vm_close,
516};
517
518static int dax_dev_mmap(struct file *filp, struct vm_area_struct *vma)
519{
520 struct dax_dev *dax_dev = filp->private_data;
521 int rc;
522
523 dev_dbg(dax_dev->dev, "%s\n", __func__);
524
525 rc = check_vma(dax_dev, vma, __func__);
526 if (rc)
527 return rc;
528
529 kref_get(&dax_dev->kref);
530 vma->vm_ops = &dax_dev_vm_ops;
531 vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
532 return 0;
533
534}
535
Dan Williamsab68f262016-05-18 09:15:08 -0700536static const struct file_operations dax_fops = {
537 .llseek = noop_llseek,
538 .owner = THIS_MODULE,
Dan Williamsdee41072016-05-14 12:20:44 -0700539 .open = dax_dev_open,
540 .release = dax_dev_release,
541 .get_unmapped_area = dax_dev_get_unmapped_area,
542 .mmap = dax_dev_mmap,
Dan Williamsab68f262016-05-18 09:15:08 -0700543};
544
545static int __init dax_init(void)
546{
547 int rc;
548
549 rc = register_chrdev(0, "dax", &dax_fops);
550 if (rc < 0)
551 return rc;
552 dax_major = rc;
553
554 dax_class = class_create(THIS_MODULE, "dax");
555 if (IS_ERR(dax_class)) {
556 unregister_chrdev(dax_major, "dax");
557 return PTR_ERR(dax_class);
558 }
559
560 return 0;
561}
562
563static void __exit dax_exit(void)
564{
565 class_destroy(dax_class);
566 unregister_chrdev(dax_major, "dax");
567 ida_destroy(&dax_minor_ida);
568}
569
570MODULE_AUTHOR("Intel Corporation");
571MODULE_LICENSE("GPL v2");
572subsys_initcall(dax_init);
573module_exit(dax_exit);