drivers/dax/device.c

   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
  17 static 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
  76 static 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
 103 static 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
 136 static 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
 180 static 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
 224 static 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
 231 static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
 232                 enum page_entry_size pe_size)
 233 {
 234         struct file *filp = vmf->vma->vm_file;
 235         vm_fault_t rc = VM_FAULT_SIGBUS;
 236         int id;
 237         struct dev_dax *dev_dax = filp->private_data;
 238
 239         dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
 240                         (vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read",
 241                         vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
 242
 243         id = dax_read_lock();
 244         switch (pe_size) {
 245         case PE_SIZE_PTE:
 246                 rc = __dev_dax_pte_fault(dev_dax, vmf);
 247                 break;
 248         case PE_SIZE_PMD:
 249                 rc = __dev_dax_pmd_fault(dev_dax, vmf);
 250                 break;
 251         case PE_SIZE_PUD:
 252                 rc = __dev_dax_pud_fault(dev_dax, vmf);
 253                 break;
 254         default:
 255                 rc = VM_FAULT_SIGBUS;
 256         }
 257
 258         dax_read_unlock(id);
 259
 260         return rc;
 261 }
 262
 263 static vm_fault_t dev_dax_fault(struct vm_fault *vmf)
 264 {
 265         return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 266 }
 267
 268 static int dev_dax_may_split(struct vm_area_struct *vma, unsigned long addr)
 269 {
 270         struct file *filp = vma->vm_file;
 271         struct dev_dax *dev_dax = filp->private_data;
 272
 273         if (!IS_ALIGNED(addr, dev_dax->align))
 274                 return -EINVAL;
 275         return 0;
 276 }
 277
 278 static unsigned long dev_dax_pagesize(struct vm_area_struct *vma)
 279 {
 280         struct file *filp = vma->vm_file;
 281         struct dev_dax *dev_dax = filp->private_data;
 282
 283         return dev_dax->align;
 284 }
 285
 286 static const struct vm_operations_struct dax_vm_ops = {
 287         .fault = dev_dax_fault,
 288         .huge_fault = dev_dax_huge_fault,
 289         .may_split = dev_dax_may_split,
 290         .pagesize = dev_dax_pagesize,
 291 };
 292
 293 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 294 {
 295         struct dev_dax *dev_dax = filp->private_data;
 296         int rc, id;
 297
 298         dev_dbg(&dev_dax->dev, "trace\n");
 299
 300         /*
 301          * We lock to check dax_dev liveness and will re-check at
 302          * fault time.
 303          */
 304         id = dax_read_lock();
 305         rc = check_vma(dev_dax, vma, __func__);
 306         dax_read_unlock(id);
 307         if (rc)
 308                 return rc;
 309
 310         vma->vm_ops = &dax_vm_ops;
 311         vma->vm_flags |= VM_HUGEPAGE;
 312         return 0;
 313 }
 314
 315 /* return an unmapped area aligned to the dax region specified alignment */
 316 static unsigned long dax_get_unmapped_area(struct file *filp,
 317                 unsigned long addr, unsigned long len, unsigned long pgoff,
 318                 unsigned long flags)
 319 {
 320         unsigned long off, off_end, off_align, len_align, addr_align, align;
 321         struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 322
 323         if (!dev_dax || addr)
 324                 goto out;
 325
 326         align = dev_dax->align;
 327         off = pgoff << PAGE_SHIFT;
 328         off_end = off + len;
 329         off_align = round_up(off, align);
 330
 331         if ((off_end <= off_align) || ((off_end - off_align) < align))
 332                 goto out;
 333
 334         len_align = len + align;
 335         if ((off + len_align) < off)
 336                 goto out;
 337
 338         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 339                         pgoff, flags);
 340         if (!IS_ERR_VALUE(addr_align)) {
 341                 addr_align += (off - addr_align) & (align - 1);
 342                 return addr_align;
 343         }
 344  out:
 345         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 346 }
 347
 348 static const struct address_space_operations dev_dax_aops = {
 349         .dirty_folio    = noop_dirty_folio,
 350 };
 351
 352 static int dax_open(struct inode *inode, struct file *filp)
 353 {
 354         struct dax_device *dax_dev = inode_dax(inode);
 355         struct inode *__dax_inode = dax_inode(dax_dev);
 356         struct dev_dax *dev_dax = dax_get_private(dax_dev);
 357
 358         dev_dbg(&dev_dax->dev, "trace\n");
 359         inode->i_mapping = __dax_inode->i_mapping;
 360         inode->i_mapping->host = __dax_inode;
 361         inode->i_mapping->a_ops = &dev_dax_aops;
 362         filp->f_mapping = inode->i_mapping;
 363         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 364         filp->f_sb_err = file_sample_sb_err(filp);
 365         filp->private_data = dev_dax;
 366         inode->i_flags = S_DAX;
 367
 368         return 0;
 369 }
 370
 371 static int dax_release(struct inode *inode, struct file *filp)
 372 {
 373         struct dev_dax *dev_dax = filp->private_data;
 374
 375         dev_dbg(&dev_dax->dev, "trace\n");
 376         return 0;
 377 }
 378
 379 static const struct file_operations dax_fops = {
 380         .llseek = noop_llseek,
 381         .owner = THIS_MODULE,
 382         .open = dax_open,
 383         .release = dax_release,
 384         .get_unmapped_area = dax_get_unmapped_area,
 385         .mmap = dax_mmap,
 386         .mmap_supported_flags = MAP_SYNC,
 387 };
 388
 389 static void dev_dax_cdev_del(void *cdev)
 390 {
 391         cdev_del(cdev);
 392 }
 393
 394 static void dev_dax_kill(void *dev_dax)
 395 {
 396         kill_dev_dax(dev_dax);
 397 }
 398
 399 int dev_dax_probe(struct dev_dax *dev_dax)
 400 {
 401         struct dax_device *dax_dev = dev_dax->dax_dev;
 402         struct device *dev = &dev_dax->dev;
 403         struct dev_pagemap *pgmap;
 404         struct inode *inode;
 405         struct cdev *cdev;
 406         void *addr;
 407         int rc, i;
 408
 409         if (static_dev_dax(dev_dax))  {
 410                 if (dev_dax->nr_range > 1) {
 411                         dev_warn(dev,
 412                                 "static pgmap / multi-range device conflict\n");
 413                         return -EINVAL;
 414                 }
 415
 416                 pgmap = dev_dax->pgmap;
 417         } else {
 418                 if (dev_dax->pgmap) {
 419                         dev_warn(dev,
 420                                  "dynamic-dax with pre-populated page map\n");
 421                         return -EINVAL;
 422                 }
 423
 424                 pgmap = devm_kzalloc(dev,
 425                        struct_size(pgmap, ranges, dev_dax->nr_range - 1),
 426                        GFP_KERNEL);
 427                 if (!pgmap)
 428                         return -ENOMEM;
 429
 430                 pgmap->nr_range = dev_dax->nr_range;
 431                 dev_dax->pgmap = pgmap;
 432
 433                 for (i = 0; i < dev_dax->nr_range; i++) {
 434                         struct range *range = &dev_dax->ranges[i].range;
 435                         pgmap->ranges[i] = *range;
 436                 }
 437         }
 438
 439         for (i = 0; i < dev_dax->nr_range; i++) {
 440                 struct range *range = &dev_dax->ranges[i].range;
 441
 442                 if (!devm_request_mem_region(dev, range->start,
 443                                         range_len(range), dev_name(dev))) {
 444                         dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve range\n",
 445                                         i, range->start, range->end);
 446                         return -EBUSY;
 447                 }
 448         }
 449
 450         pgmap->type = MEMORY_DEVICE_GENERIC;
 451         if (dev_dax->align > PAGE_SIZE)
 452                 pgmap->vmemmap_shift =
 453                         order_base_2(dev_dax->align >> PAGE_SHIFT);
 454         addr = devm_memremap_pages(dev, pgmap);
 455         if (IS_ERR(addr))
 456                 return PTR_ERR(addr);
 457
 458         inode = dax_inode(dax_dev);
 459         cdev = inode->i_cdev;
 460         cdev_init(cdev, &dax_fops);
 461         cdev->owner = dev->driver->owner;
 462         cdev_set_parent(cdev, &dev->kobj);
 463         rc = cdev_add(cdev, dev->devt, 1);
 464         if (rc)
 465                 return rc;
 466
 467         rc = devm_add_action_or_reset(dev, dev_dax_cdev_del, cdev);
 468         if (rc)
 469                 return rc;
 470
 471         run_dax(dax_dev);
 472         return devm_add_action_or_reset(dev, dev_dax_kill, dev_dax);
 473 }
 474 EXPORT_SYMBOL_GPL(dev_dax_probe);
 475
 476 static struct dax_device_driver device_dax_driver = {
 477         .probe = dev_dax_probe,
 478         /* all probe actions are unwound by devm, so .remove isn't necessary */
 479         .match_always = 1,
 480 };
 481
 482 static int __init dax_init(void)
 483 {
 484         return dax_driver_register(&device_dax_driver);
 485 }
 486
 487 static void __exit dax_exit(void)
 488 {
 489         dax_driver_unregister(&device_dax_driver);
 490 }
 491
 492 MODULE_AUTHOR("Intel Corporation");
 493 MODULE_LICENSE("GPL v2");
 494 module_init(dax_init);
 495 module_exit(dax_exit);
 496 MODULE_ALIAS_DAX_DEVICE(0);