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