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