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 struct dev_dax *ref_to_dev_dax(struct percpu_ref *ref) 18 { 19 return container_of(ref, struct dev_dax, ref); 20 } 21 22 static void dev_dax_percpu_release(struct percpu_ref *ref) 23 { 24 struct dev_dax *dev_dax = ref_to_dev_dax(ref); 25 26 dev_dbg(&dev_dax->dev, "%s\n", __func__); 27 complete(&dev_dax->cmp); 28 } 29 30 static void dev_dax_percpu_exit(void *data) 31 { 32 struct percpu_ref *ref = data; 33 struct dev_dax *dev_dax = ref_to_dev_dax(ref); 34 35 dev_dbg(&dev_dax->dev, "%s\n", __func__); 36 wait_for_completion(&dev_dax->cmp); 37 percpu_ref_exit(ref); 38 } 39 40 static void dev_dax_percpu_kill(struct percpu_ref *data) 41 { 42 struct percpu_ref *ref = data; 43 struct dev_dax *dev_dax = ref_to_dev_dax(ref); 44 45 dev_dbg(&dev_dax->dev, "%s\n", __func__); 46 percpu_ref_kill(ref); 47 } 48 49 static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma, 50 const char *func) 51 { 52 struct dax_region *dax_region = dev_dax->region; 53 struct device *dev = &dev_dax->dev; 54 unsigned long mask; 55 56 if (!dax_alive(dev_dax->dax_dev)) 57 return -ENXIO; 58 59 /* prevent private mappings from being established */ 60 if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) { 61 dev_info_ratelimited(dev, 62 "%s: %s: fail, attempted private mapping\n", 63 current->comm, func); 64 return -EINVAL; 65 } 66 67 mask = dax_region->align - 1; 68 if (vma->vm_start & mask || vma->vm_end & mask) { 69 dev_info_ratelimited(dev, 70 "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n", 71 current->comm, func, vma->vm_start, vma->vm_end, 72 mask); 73 return -EINVAL; 74 } 75 76 if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV 77 && (vma->vm_flags & VM_DONTCOPY) == 0) { 78 dev_info_ratelimited(dev, 79 "%s: %s: fail, dax range requires MADV_DONTFORK\n", 80 current->comm, func); 81 return -EINVAL; 82 } 83 84 if (!vma_is_dax(vma)) { 85 dev_info_ratelimited(dev, 86 "%s: %s: fail, vma is not DAX capable\n", 87 current->comm, func); 88 return -EINVAL; 89 } 90 91 return 0; 92 } 93 94 /* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */ 95 __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff, 96 unsigned long size) 97 { 98 struct resource *res = &dev_dax->region->res; 99 phys_addr_t phys; 100 101 phys = pgoff * PAGE_SIZE + res->start; 102 if (phys >= res->start && phys <= res->end) { 103 if (phys + size - 1 <= res->end) 104 return phys; 105 } 106 107 return -1; 108 } 109 110 static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax, 111 struct vm_fault *vmf, pfn_t *pfn) 112 { 113 struct device *dev = &dev_dax->dev; 114 struct dax_region *dax_region; 115 phys_addr_t phys; 116 unsigned int fault_size = PAGE_SIZE; 117 118 if (check_vma(dev_dax, vmf->vma, __func__)) 119 return VM_FAULT_SIGBUS; 120 121 dax_region = dev_dax->region; 122 if (dax_region->align > PAGE_SIZE) { 123 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n", 124 dax_region->align, fault_size); 125 return VM_FAULT_SIGBUS; 126 } 127 128 if (fault_size != dax_region->align) 129 return VM_FAULT_SIGBUS; 130 131 phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE); 132 if (phys == -1) { 133 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", vmf->pgoff); 134 return VM_FAULT_SIGBUS; 135 } 136 137 *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags); 138 139 return vmf_insert_mixed(vmf->vma, vmf->address, *pfn); 140 } 141 142 static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax, 143 struct vm_fault *vmf, pfn_t *pfn) 144 { 145 unsigned long pmd_addr = vmf->address & PMD_MASK; 146 struct device *dev = &dev_dax->dev; 147 struct dax_region *dax_region; 148 phys_addr_t phys; 149 pgoff_t pgoff; 150 unsigned int fault_size = PMD_SIZE; 151 152 if (check_vma(dev_dax, vmf->vma, __func__)) 153 return VM_FAULT_SIGBUS; 154 155 dax_region = dev_dax->region; 156 if (dax_region->align > PMD_SIZE) { 157 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n", 158 dax_region->align, fault_size); 159 return VM_FAULT_SIGBUS; 160 } 161 162 /* dax pmd mappings require pfn_t_devmap() */ 163 if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) { 164 dev_dbg(dev, "region lacks devmap flags\n"); 165 return VM_FAULT_SIGBUS; 166 } 167 168 if (fault_size < dax_region->align) 169 return VM_FAULT_SIGBUS; 170 else if (fault_size > dax_region->align) 171 return VM_FAULT_FALLBACK; 172 173 /* if we are outside of the VMA */ 174 if (pmd_addr < vmf->vma->vm_start || 175 (pmd_addr + PMD_SIZE) > vmf->vma->vm_end) 176 return VM_FAULT_SIGBUS; 177 178 pgoff = linear_page_index(vmf->vma, pmd_addr); 179 phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE); 180 if (phys == -1) { 181 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff); 182 return VM_FAULT_SIGBUS; 183 } 184 185 *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags); 186 187 return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, *pfn, 188 vmf->flags & FAULT_FLAG_WRITE); 189 } 190 191 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 192 static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax, 193 struct vm_fault *vmf, pfn_t *pfn) 194 { 195 unsigned long pud_addr = vmf->address & PUD_MASK; 196 struct device *dev = &dev_dax->dev; 197 struct dax_region *dax_region; 198 phys_addr_t phys; 199 pgoff_t pgoff; 200 unsigned int fault_size = PUD_SIZE; 201 202 203 if (check_vma(dev_dax, vmf->vma, __func__)) 204 return VM_FAULT_SIGBUS; 205 206 dax_region = dev_dax->region; 207 if (dax_region->align > PUD_SIZE) { 208 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n", 209 dax_region->align, fault_size); 210 return VM_FAULT_SIGBUS; 211 } 212 213 /* dax pud mappings require pfn_t_devmap() */ 214 if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) { 215 dev_dbg(dev, "region lacks devmap flags\n"); 216 return VM_FAULT_SIGBUS; 217 } 218 219 if (fault_size < dax_region->align) 220 return VM_FAULT_SIGBUS; 221 else if (fault_size > dax_region->align) 222 return VM_FAULT_FALLBACK; 223 224 /* if we are outside of the VMA */ 225 if (pud_addr < vmf->vma->vm_start || 226 (pud_addr + PUD_SIZE) > vmf->vma->vm_end) 227 return VM_FAULT_SIGBUS; 228 229 pgoff = linear_page_index(vmf->vma, pud_addr); 230 phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE); 231 if (phys == -1) { 232 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff); 233 return VM_FAULT_SIGBUS; 234 } 235 236 *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags); 237 238 return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, *pfn, 239 vmf->flags & FAULT_FLAG_WRITE); 240 } 241 #else 242 static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax, 243 struct vm_fault *vmf, pfn_t *pfn) 244 { 245 return VM_FAULT_FALLBACK; 246 } 247 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 248 249 static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf, 250 enum page_entry_size pe_size) 251 { 252 struct file *filp = vmf->vma->vm_file; 253 unsigned long fault_size; 254 vm_fault_t rc = VM_FAULT_SIGBUS; 255 int id; 256 pfn_t pfn; 257 struct dev_dax *dev_dax = filp->private_data; 258 259 dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm, 260 (vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read", 261 vmf->vma->vm_start, vmf->vma->vm_end, pe_size); 262 263 id = dax_read_lock(); 264 switch (pe_size) { 265 case PE_SIZE_PTE: 266 fault_size = PAGE_SIZE; 267 rc = __dev_dax_pte_fault(dev_dax, vmf, &pfn); 268 break; 269 case PE_SIZE_PMD: 270 fault_size = PMD_SIZE; 271 rc = __dev_dax_pmd_fault(dev_dax, vmf, &pfn); 272 break; 273 case PE_SIZE_PUD: 274 fault_size = PUD_SIZE; 275 rc = __dev_dax_pud_fault(dev_dax, vmf, &pfn); 276 break; 277 default: 278 rc = VM_FAULT_SIGBUS; 279 } 280 281 if (rc == VM_FAULT_NOPAGE) { 282 unsigned long i; 283 pgoff_t pgoff; 284 285 /* 286 * In the device-dax case the only possibility for a 287 * VM_FAULT_NOPAGE result is when device-dax capacity is 288 * mapped. No need to consider the zero page, or racing 289 * conflicting mappings. 290 */ 291 pgoff = linear_page_index(vmf->vma, vmf->address 292 & ~(fault_size - 1)); 293 for (i = 0; i < fault_size / PAGE_SIZE; i++) { 294 struct page *page; 295 296 page = pfn_to_page(pfn_t_to_pfn(pfn) + i); 297 if (page->mapping) 298 continue; 299 page->mapping = filp->f_mapping; 300 page->index = pgoff + i; 301 } 302 } 303 dax_read_unlock(id); 304 305 return rc; 306 } 307 308 static vm_fault_t dev_dax_fault(struct vm_fault *vmf) 309 { 310 return dev_dax_huge_fault(vmf, PE_SIZE_PTE); 311 } 312 313 static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr) 314 { 315 struct file *filp = vma->vm_file; 316 struct dev_dax *dev_dax = filp->private_data; 317 struct dax_region *dax_region = dev_dax->region; 318 319 if (!IS_ALIGNED(addr, dax_region->align)) 320 return -EINVAL; 321 return 0; 322 } 323 324 static unsigned long dev_dax_pagesize(struct vm_area_struct *vma) 325 { 326 struct file *filp = vma->vm_file; 327 struct dev_dax *dev_dax = filp->private_data; 328 struct dax_region *dax_region = dev_dax->region; 329 330 return dax_region->align; 331 } 332 333 static const struct vm_operations_struct dax_vm_ops = { 334 .fault = dev_dax_fault, 335 .huge_fault = dev_dax_huge_fault, 336 .split = dev_dax_split, 337 .pagesize = dev_dax_pagesize, 338 }; 339 340 static int dax_mmap(struct file *filp, struct vm_area_struct *vma) 341 { 342 struct dev_dax *dev_dax = filp->private_data; 343 int rc, id; 344 345 dev_dbg(&dev_dax->dev, "trace\n"); 346 347 /* 348 * We lock to check dax_dev liveness and will re-check at 349 * fault time. 350 */ 351 id = dax_read_lock(); 352 rc = check_vma(dev_dax, vma, __func__); 353 dax_read_unlock(id); 354 if (rc) 355 return rc; 356 357 vma->vm_ops = &dax_vm_ops; 358 vma->vm_flags |= VM_HUGEPAGE; 359 return 0; 360 } 361 362 /* return an unmapped area aligned to the dax region specified alignment */ 363 static unsigned long dax_get_unmapped_area(struct file *filp, 364 unsigned long addr, unsigned long len, unsigned long pgoff, 365 unsigned long flags) 366 { 367 unsigned long off, off_end, off_align, len_align, addr_align, align; 368 struct dev_dax *dev_dax = filp ? filp->private_data : NULL; 369 struct dax_region *dax_region; 370 371 if (!dev_dax || addr) 372 goto out; 373 374 dax_region = dev_dax->region; 375 align = dax_region->align; 376 off = pgoff << PAGE_SHIFT; 377 off_end = off + len; 378 off_align = round_up(off, align); 379 380 if ((off_end <= off_align) || ((off_end - off_align) < align)) 381 goto out; 382 383 len_align = len + align; 384 if ((off + len_align) < off) 385 goto out; 386 387 addr_align = current->mm->get_unmapped_area(filp, addr, len_align, 388 pgoff, flags); 389 if (!IS_ERR_VALUE(addr_align)) { 390 addr_align += (off - addr_align) & (align - 1); 391 return addr_align; 392 } 393 out: 394 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 395 } 396 397 static const struct address_space_operations dev_dax_aops = { 398 .set_page_dirty = noop_set_page_dirty, 399 .invalidatepage = noop_invalidatepage, 400 }; 401 402 static int dax_open(struct inode *inode, struct file *filp) 403 { 404 struct dax_device *dax_dev = inode_dax(inode); 405 struct inode *__dax_inode = dax_inode(dax_dev); 406 struct dev_dax *dev_dax = dax_get_private(dax_dev); 407 408 dev_dbg(&dev_dax->dev, "trace\n"); 409 inode->i_mapping = __dax_inode->i_mapping; 410 inode->i_mapping->host = __dax_inode; 411 inode->i_mapping->a_ops = &dev_dax_aops; 412 filp->f_mapping = inode->i_mapping; 413 filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping); 414 filp->private_data = dev_dax; 415 inode->i_flags = S_DAX; 416 417 return 0; 418 } 419 420 static int dax_release(struct inode *inode, struct file *filp) 421 { 422 struct dev_dax *dev_dax = filp->private_data; 423 424 dev_dbg(&dev_dax->dev, "trace\n"); 425 return 0; 426 } 427 428 static const struct file_operations dax_fops = { 429 .llseek = noop_llseek, 430 .owner = THIS_MODULE, 431 .open = dax_open, 432 .release = dax_release, 433 .get_unmapped_area = dax_get_unmapped_area, 434 .mmap = dax_mmap, 435 .mmap_supported_flags = MAP_SYNC, 436 }; 437 438 static void dev_dax_cdev_del(void *cdev) 439 { 440 cdev_del(cdev); 441 } 442 443 static void dev_dax_kill(void *dev_dax) 444 { 445 kill_dev_dax(dev_dax); 446 } 447 448 int dev_dax_probe(struct device *dev) 449 { 450 struct dev_dax *dev_dax = to_dev_dax(dev); 451 struct dax_device *dax_dev = dev_dax->dax_dev; 452 struct resource *res = &dev_dax->region->res; 453 struct inode *inode; 454 struct cdev *cdev; 455 void *addr; 456 int rc; 457 458 /* 1:1 map region resource range to device-dax instance range */ 459 if (!devm_request_mem_region(dev, res->start, resource_size(res), 460 dev_name(dev))) { 461 dev_warn(dev, "could not reserve region %pR\n", res); 462 return -EBUSY; 463 } 464 465 init_completion(&dev_dax->cmp); 466 rc = percpu_ref_init(&dev_dax->ref, dev_dax_percpu_release, 0, 467 GFP_KERNEL); 468 if (rc) 469 return rc; 470 471 rc = devm_add_action_or_reset(dev, dev_dax_percpu_exit, &dev_dax->ref); 472 if (rc) 473 return rc; 474 475 dev_dax->pgmap.ref = &dev_dax->ref; 476 dev_dax->pgmap.kill = dev_dax_percpu_kill; 477 addr = devm_memremap_pages(dev, &dev_dax->pgmap); 478 if (IS_ERR(addr)) { 479 devm_remove_action(dev, dev_dax_percpu_exit, &dev_dax->ref); 480 percpu_ref_exit(&dev_dax->ref); 481 return PTR_ERR(addr); 482 } 483 484 inode = dax_inode(dax_dev); 485 cdev = inode->i_cdev; 486 cdev_init(cdev, &dax_fops); 487 if (dev->class) { 488 /* for the CONFIG_DEV_DAX_PMEM_COMPAT case */ 489 cdev->owner = dev->parent->driver->owner; 490 } else 491 cdev->owner = dev->driver->owner; 492 cdev_set_parent(cdev, &dev->kobj); 493 rc = cdev_add(cdev, dev->devt, 1); 494 if (rc) 495 return rc; 496 497 rc = devm_add_action_or_reset(dev, dev_dax_cdev_del, cdev); 498 if (rc) 499 return rc; 500 501 run_dax(dax_dev); 502 return devm_add_action_or_reset(dev, dev_dax_kill, dev_dax); 503 } 504 EXPORT_SYMBOL_GPL(dev_dax_probe); 505 506 static int dev_dax_remove(struct device *dev) 507 { 508 /* all probe actions are unwound by devm */ 509 return 0; 510 } 511 512 static struct dax_device_driver device_dax_driver = { 513 .drv = { 514 .probe = dev_dax_probe, 515 .remove = dev_dax_remove, 516 }, 517 .match_always = 1, 518 }; 519 520 static int __init dax_init(void) 521 { 522 return dax_driver_register(&device_dax_driver); 523 } 524 525 static void __exit dax_exit(void) 526 { 527 dax_driver_unregister(&device_dax_driver); 528 } 529 530 MODULE_AUTHOR("Intel Corporation"); 531 MODULE_LICENSE("GPL v2"); 532 module_init(dax_init); 533 module_exit(dax_exit); 534 MODULE_ALIAS_DAX_DEVICE(0); 535