1// SPDX-License-Identifier: GPL-2.0
2/* Copyright(c) 2016-2018 Intel Corporation. All rights reserved. */
3#include <linux/memremap.h>
4#include <linux/pagemap.h>
5#include <linux/module.h>
6#include <linux/device.h>
7#include <linux/cdev.h>
8#include <linux/slab.h>
9#include <linux/dax.h>
10#include <linux/fs.h>
11#include <linux/mm.h>
12#include <linux/mman.h>
13#include "dax-private.h"
14#include "bus.h"
15
16static int __check_vma(struct dev_dax *dev_dax, vm_flags_t vm_flags,
17 unsigned long start, unsigned long end, struct file *file,
18 const char *func)
19{
20 struct device *dev = &dev_dax->dev;
21 unsigned long mask;
22
23 if (!dax_alive(dax_dev: dev_dax->dax_dev))
24 return -ENXIO;
25
26 /* prevent private mappings from being established */
27 if ((vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
28 dev_info_ratelimited(dev,
29 "%s: %s: fail, attempted private mapping\n",
30 current->comm, func);
31 return -EINVAL;
32 }
33
34 mask = dev_dax->align - 1;
35 if (start & mask || end & mask) {
36 dev_info_ratelimited(dev,
37 "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
38 current->comm, func, start, end,
39 mask);
40 return -EINVAL;
41 }
42
43 if (!file_is_dax(file)) {
44 dev_info_ratelimited(dev,
45 "%s: %s: fail, vma is not DAX capable\n",
46 current->comm, func);
47 return -EINVAL;
48 }
49
50 return 0;
51}
52
53static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
54 const char *func)
55{
56 return __check_vma(dev_dax, vm_flags: vma->vm_flags, start: vma->vm_start, end: vma->vm_end,
57 file: vma->vm_file, func);
58}
59
60/* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
61__weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
62 unsigned long size)
63{
64 int i;
65
66 for (i = 0; i < dev_dax->nr_range; i++) {
67 struct dev_dax_range *dax_range = &dev_dax->ranges[i];
68 struct range *range = &dax_range->range;
69 unsigned long long pgoff_end;
70 phys_addr_t phys;
71
72 pgoff_end = dax_range->pgoff + PHYS_PFN(range_len(range)) - 1;
73 if (pgoff < dax_range->pgoff || pgoff > pgoff_end)
74 continue;
75 phys = PFN_PHYS(pgoff - dax_range->pgoff) + range->start;
76 if (phys + size - 1 <= range->end)
77 return phys;
78 break;
79 }
80 return -1;
81}
82
83static void dax_set_mapping(struct vm_fault *vmf, unsigned long pfn,
84 unsigned long fault_size)
85{
86 unsigned long i, nr_pages = fault_size / PAGE_SIZE;
87 struct file *filp = vmf->vma->vm_file;
88 struct dev_dax *dev_dax = filp->private_data;
89 pgoff_t pgoff;
90
91 /* mapping is only set on the head */
92 if (dev_dax->pgmap->vmemmap_shift)
93 nr_pages = 1;
94
95 pgoff = linear_page_index(vma: vmf->vma,
96 ALIGN_DOWN(vmf->address, fault_size));
97
98 for (i = 0; i < nr_pages; i++) {
99 struct folio *folio = pfn_folio(pfn: pfn + i);
100
101 if (folio->mapping)
102 continue;
103
104 folio->mapping = filp->f_mapping;
105 folio->index = pgoff + i;
106 }
107}
108
109static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
110 struct vm_fault *vmf)
111{
112 struct device *dev = &dev_dax->dev;
113 phys_addr_t phys;
114 unsigned long pfn;
115 unsigned int fault_size = PAGE_SIZE;
116
117 if (check_vma(dev_dax, vma: vmf->vma, func: __func__))
118 return VM_FAULT_SIGBUS;
119
120 if (dev_dax->align > PAGE_SIZE) {
121 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
122 dev_dax->align, fault_size);
123 return VM_FAULT_SIGBUS;
124 }
125
126 if (fault_size != dev_dax->align)
127 return VM_FAULT_SIGBUS;
128
129 phys = dax_pgoff_to_phys(dev_dax, pgoff: vmf->pgoff, PAGE_SIZE);
130 if (phys == -1) {
131 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", vmf->pgoff);
132 return VM_FAULT_SIGBUS;
133 }
134
135 pfn = PHYS_PFN(phys);
136
137 dax_set_mapping(vmf, pfn, fault_size);
138
139 return vmf_insert_page_mkwrite(vmf, pfn_to_page(pfn),
140 write: vmf->flags & FAULT_FLAG_WRITE);
141}
142
143static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
144 struct vm_fault *vmf)
145{
146 unsigned long pmd_addr = vmf->address & PMD_MASK;
147 struct device *dev = &dev_dax->dev;
148 phys_addr_t phys;
149 pgoff_t pgoff;
150 unsigned long pfn;
151 unsigned int fault_size = PMD_SIZE;
152
153 if (check_vma(dev_dax, vma: vmf->vma, func: __func__))
154 return VM_FAULT_SIGBUS;
155
156 if (dev_dax->align > PMD_SIZE) {
157 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
158 dev_dax->align, fault_size);
159 return VM_FAULT_SIGBUS;
160 }
161
162 if (fault_size < dev_dax->align)
163 return VM_FAULT_SIGBUS;
164 else if (fault_size > dev_dax->align)
165 return VM_FAULT_FALLBACK;
166
167 /* if we are outside of the VMA */
168 if (pmd_addr < vmf->vma->vm_start ||
169 (pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
170 return VM_FAULT_SIGBUS;
171
172 pgoff = linear_page_index(vma: vmf->vma, address: pmd_addr);
173 phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
174 if (phys == -1) {
175 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
176 return VM_FAULT_SIGBUS;
177 }
178
179 pfn = PHYS_PFN(phys);
180
181 dax_set_mapping(vmf, pfn, fault_size);
182
183 return vmf_insert_folio_pmd(vmf, page_folio(pfn_to_page(pfn)),
184 write: vmf->flags & FAULT_FLAG_WRITE);
185}
186
187#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
188static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
189 struct vm_fault *vmf)
190{
191 unsigned long pud_addr = vmf->address & PUD_MASK;
192 struct device *dev = &dev_dax->dev;
193 phys_addr_t phys;
194 pgoff_t pgoff;
195 unsigned long pfn;
196 unsigned int fault_size = PUD_SIZE;
197
198
199 if (check_vma(dev_dax, vma: vmf->vma, func: __func__))
200 return VM_FAULT_SIGBUS;
201
202 if (dev_dax->align > PUD_SIZE) {
203 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
204 dev_dax->align, fault_size);
205 return VM_FAULT_SIGBUS;
206 }
207
208 if (fault_size < dev_dax->align)
209 return VM_FAULT_SIGBUS;
210 else if (fault_size > dev_dax->align)
211 return VM_FAULT_FALLBACK;
212
213 /* if we are outside of the VMA */
214 if (pud_addr < vmf->vma->vm_start ||
215 (pud_addr + PUD_SIZE) > vmf->vma->vm_end)
216 return VM_FAULT_SIGBUS;
217
218 pgoff = linear_page_index(vma: vmf->vma, address: pud_addr);
219 phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
220 if (phys == -1) {
221 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
222 return VM_FAULT_SIGBUS;
223 }
224
225 pfn = PHYS_PFN(phys);
226
227 dax_set_mapping(vmf, pfn, fault_size);
228
229 return vmf_insert_folio_pud(vmf, page_folio(pfn_to_page(pfn)),
230 write: vmf->flags & FAULT_FLAG_WRITE);
231}
232#else
233static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
234 struct vm_fault *vmf)
235{
236 return VM_FAULT_FALLBACK;
237}
238#endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
239
240static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf, unsigned int order)
241{
242 struct file *filp = vmf->vma->vm_file;
243 vm_fault_t rc = VM_FAULT_SIGBUS;
244 int id;
245 struct dev_dax *dev_dax = filp->private_data;
246
247 dev_dbg(&dev_dax->dev, "%s: op=%s addr=%#lx order=%d\n", current->comm,
248 (vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read",
249 vmf->address & ~((1UL << (order + PAGE_SHIFT)) - 1), order);
250
251 id = dax_read_lock();
252 if (order == 0)
253 rc = __dev_dax_pte_fault(dev_dax, vmf);
254 else if (order == PMD_ORDER)
255 rc = __dev_dax_pmd_fault(dev_dax, vmf);
256 else if (order == PUD_ORDER)
257 rc = __dev_dax_pud_fault(dev_dax, vmf);
258 else
259 rc = VM_FAULT_SIGBUS;
260
261 dax_read_unlock(id);
262
263 return rc;
264}
265
266static vm_fault_t dev_dax_fault(struct vm_fault *vmf)
267{
268 return dev_dax_huge_fault(vmf, order: 0);
269}
270
271static int dev_dax_may_split(struct vm_area_struct *vma, unsigned long addr)
272{
273 struct file *filp = vma->vm_file;
274 struct dev_dax *dev_dax = filp->private_data;
275
276 if (!IS_ALIGNED(addr, dev_dax->align))
277 return -EINVAL;
278 return 0;
279}
280
281static unsigned long dev_dax_pagesize(struct vm_area_struct *vma)
282{
283 struct file *filp = vma->vm_file;
284 struct dev_dax *dev_dax = filp->private_data;
285
286 return dev_dax->align;
287}
288
289static const struct vm_operations_struct dax_vm_ops = {
290 .fault = dev_dax_fault,
291 .huge_fault = dev_dax_huge_fault,
292 .may_split = dev_dax_may_split,
293 .pagesize = dev_dax_pagesize,
294};
295
296static int dax_mmap_prepare(struct vm_area_desc *desc)
297{
298 struct file *filp = desc->file;
299 struct dev_dax *dev_dax = filp->private_data;
300 int rc, id;
301
302 dev_dbg(&dev_dax->dev, "trace\n");
303
304 /*
305 * We lock to check dax_dev liveness and will re-check at
306 * fault time.
307 */
308 id = dax_read_lock();
309 rc = __check_vma(dev_dax, vm_flags: desc->vm_flags, start: desc->start, end: desc->end, file: filp,
310 func: __func__);
311 dax_read_unlock(id);
312 if (rc)
313 return rc;
314
315 desc->vm_ops = &dax_vm_ops;
316 desc->vm_flags |= VM_HUGEPAGE;
317 return 0;
318}
319
320/* return an unmapped area aligned to the dax region specified alignment */
321static unsigned long dax_get_unmapped_area(struct file *filp,
322 unsigned long addr, unsigned long len, unsigned long pgoff,
323 unsigned long flags)
324{
325 unsigned long off, off_end, off_align, len_align, addr_align, align;
326 struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
327
328 if (!dev_dax || addr)
329 goto out;
330
331 align = dev_dax->align;
332 off = pgoff << PAGE_SHIFT;
333 off_end = off + len;
334 off_align = round_up(off, align);
335
336 if ((off_end <= off_align) || ((off_end - off_align) < align))
337 goto out;
338
339 len_align = len + align;
340 if ((off + len_align) < off)
341 goto out;
342
343 addr_align = mm_get_unmapped_area(filp, addr, len: len_align, pgoff, flags);
344 if (!IS_ERR_VALUE(addr_align)) {
345 addr_align += (off - addr_align) & (align - 1);
346 return addr_align;
347 }
348 out:
349 return mm_get_unmapped_area(filp, addr, len, pgoff, flags);
350}
351
352static const struct address_space_operations dev_dax_aops = {
353 .dirty_folio = noop_dirty_folio,
354};
355
356static int dax_open(struct inode *inode, struct file *filp)
357{
358 struct dax_device *dax_dev = inode_dax(inode);
359 struct inode *__dax_inode = dax_inode(dax_dev);
360 struct dev_dax *dev_dax = dax_get_private(dax_dev);
361
362 dev_dbg(&dev_dax->dev, "trace\n");
363 inode->i_mapping = __dax_inode->i_mapping;
364 inode->i_mapping->host = __dax_inode;
365 inode->i_mapping->a_ops = &dev_dax_aops;
366 filp->f_mapping = inode->i_mapping;
367 filp->f_wb_err = filemap_sample_wb_err(mapping: filp->f_mapping);
368 filp->f_sb_err = file_sample_sb_err(file: filp);
369 filp->private_data = dev_dax;
370 inode->i_flags = S_DAX;
371
372 return 0;
373}
374
375static int dax_release(struct inode *inode, struct file *filp)
376{
377 struct dev_dax *dev_dax = filp->private_data;
378
379 dev_dbg(&dev_dax->dev, "trace\n");
380 return 0;
381}
382
383static const struct file_operations dax_fops = {
384 .llseek = noop_llseek,
385 .owner = THIS_MODULE,
386 .open = dax_open,
387 .release = dax_release,
388 .get_unmapped_area = dax_get_unmapped_area,
389 .mmap_prepare = dax_mmap_prepare,
390 .fop_flags = FOP_MMAP_SYNC,
391};
392
393static void dev_dax_cdev_del(void *cdev)
394{
395 cdev_del(cdev);
396}
397
398static void dev_dax_kill(void *dev_dax)
399{
400 kill_dev_dax(dev_dax);
401}
402
403static int dev_dax_probe(struct dev_dax *dev_dax)
404{
405 struct dax_device *dax_dev = dev_dax->dax_dev;
406 struct device *dev = &dev_dax->dev;
407 struct dev_pagemap *pgmap;
408 struct inode *inode;
409 struct cdev *cdev;
410 void *addr;
411 int rc, i;
412
413 if (static_dev_dax(dev_dax)) {
414 if (dev_dax->nr_range > 1) {
415 dev_warn(dev,
416 "static pgmap / multi-range device conflict\n");
417 return -EINVAL;
418 }
419
420 pgmap = dev_dax->pgmap;
421 } else {
422 if (dev_dax->pgmap) {
423 dev_warn(dev,
424 "dynamic-dax with pre-populated page map\n");
425 return -EINVAL;
426 }
427
428 pgmap = devm_kzalloc(dev,
429 struct_size(pgmap, ranges, dev_dax->nr_range - 1),
430 GFP_KERNEL);
431 if (!pgmap)
432 return -ENOMEM;
433
434 pgmap->nr_range = dev_dax->nr_range;
435 dev_dax->pgmap = pgmap;
436
437 for (i = 0; i < dev_dax->nr_range; i++) {
438 struct range *range = &dev_dax->ranges[i].range;
439 pgmap->ranges[i] = *range;
440 }
441 }
442
443 for (i = 0; i < dev_dax->nr_range; i++) {
444 struct range *range = &dev_dax->ranges[i].range;
445
446 if (!devm_request_mem_region(dev, range->start,
447 range_len(range), dev_name(dev))) {
448 dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve range\n",
449 i, range->start, range->end);
450 return -EBUSY;
451 }
452 }
453
454 pgmap->type = MEMORY_DEVICE_GENERIC;
455 if (dev_dax->align > PAGE_SIZE)
456 pgmap->vmemmap_shift =
457 order_base_2(dev_dax->align >> PAGE_SHIFT);
458 addr = devm_memremap_pages(dev, pgmap);
459 if (IS_ERR(ptr: addr))
460 return PTR_ERR(ptr: addr);
461
462 inode = dax_inode(dax_dev);
463 cdev = inode->i_cdev;
464 cdev_init(cdev, &dax_fops);
465 cdev->owner = dev->driver->owner;
466 cdev_set_parent(p: cdev, kobj: &dev->kobj);
467 rc = cdev_add(cdev, dev->devt, 1);
468 if (rc)
469 return rc;
470
471 rc = devm_add_action_or_reset(dev, dev_dax_cdev_del, cdev);
472 if (rc)
473 return rc;
474
475 run_dax(dax_dev);
476 return devm_add_action_or_reset(dev, dev_dax_kill, dev_dax);
477}
478
479static struct dax_device_driver device_dax_driver = {
480 .probe = dev_dax_probe,
481 .type = DAXDRV_DEVICE_TYPE,
482};
483
484static int __init dax_init(void)
485{
486 return dax_driver_register(&device_dax_driver);
487}
488
489static void __exit dax_exit(void)
490{
491 dax_driver_unregister(dax_drv: &device_dax_driver);
492}
493
494MODULE_AUTHOR("Intel Corporation");
495MODULE_DESCRIPTION("Device DAX: direct access device driver");
496MODULE_LICENSE("GPL v2");
497module_init(dax_init);
498module_exit(dax_exit);
499MODULE_ALIAS_DAX_DEVICE(0);
500

source code of linux/drivers/dax/device.c