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, 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
 257 static vm_fault_t dev_dax_fault(struct vm_fault *vmf)
 258 {
 259         return dev_dax_huge_fault(vmf, 0);
 260 }
 261
 262 static 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
 272 static 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
 280 static 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
 287 static 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 */
 310 static 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
 342 static const struct address_space_operations dev_dax_aops = {
 343         .dirty_folio    = noop_dirty_folio,
 344 };
 345
 346 static 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
 365 static 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
 373 static 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
 383 static void dev_dax_cdev_del(void *cdev)
 384 {
 385         cdev_del(cdev);
 386 }
 387
 388 static void dev_dax_kill(void *dev_dax)
 389 {
 390         kill_dev_dax(dev_dax);
 391 }
 392
 393 static 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
 469 static struct dax_device_driver device_dax_driver = {
 470         .probe = dev_dax_probe,
 471         .type = DAXDRV_DEVICE_TYPE,
 472 };
 473
 474 static int __init dax_init(void)
 475 {
 476         return dax_driver_register(&device_dax_driver);
 477 }
 478
 479 static void __exit dax_exit(void)
 480 {
 481         dax_driver_unregister(&device_dax_driver);
 482 }
 483
 484 MODULE_AUTHOR("Intel Corporation");
 485 MODULE_LICENSE("GPL v2");
 486 module_init(dax_init);
 487 module_exit(dax_exit);
 488 MODULE_ALIAS_DAX_DEVICE(0);