drivers/base/memory.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Memory subsystem support
   4  *
   5  * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
   6  *            Dave Hansen <haveblue@us.ibm.com>
   7  *
   8  * This file provides the necessary infrastructure to represent
   9  * a SPARSEMEM-memory-model system's physical memory in /sysfs.
  10  * All arch-independent code that assumes MEMORY_HOTPLUG requires
  11  * SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/topology.h>
  17 #include <linux/capability.h>
  18 #include <linux/device.h>
  19 #include <linux/memory.h>
  20 #include <linux/memory_hotplug.h>
  21 #include <linux/mm.h>
  22 #include <linux/mutex.h>
  23 #include <linux/stat.h>
  24 #include <linux/slab.h>
  25
  26 #include <linux/atomic.h>
  27 #include <linux/uaccess.h>
  28
  29 static DEFINE_MUTEX(mem_sysfs_mutex);
  30
  31 #define MEMORY_CLASS_NAME       "memory"
  32
  33 #define to_memory_block(dev) container_of(dev, struct memory_block, dev)
  34
  35 static int sections_per_block;
  36
  37 static inline unsigned long base_memory_block_id(unsigned long section_nr)
  38 {
  39         return section_nr / sections_per_block;
  40 }
  41
  42 static inline unsigned long pfn_to_block_id(unsigned long pfn)
  43 {
  44         return base_memory_block_id(pfn_to_section_nr(pfn));
  45 }
  46
  47 static inline unsigned long phys_to_block_id(unsigned long phys)
  48 {
  49         return pfn_to_block_id(PFN_DOWN(phys));
  50 }
  51
  52 static int memory_subsys_online(struct device *dev);
  53 static int memory_subsys_offline(struct device *dev);
  54
  55 static struct bus_type memory_subsys = {
  56         .name = MEMORY_CLASS_NAME,
  57         .dev_name = MEMORY_CLASS_NAME,
  58         .online = memory_subsys_online,
  59         .offline = memory_subsys_offline,
  60 };
  61
  62 static BLOCKING_NOTIFIER_HEAD(memory_chain);
  63
  64 int register_memory_notifier(struct notifier_block *nb)
  65 {
  66         return blocking_notifier_chain_register(&memory_chain, nb);
  67 }
  68 EXPORT_SYMBOL(register_memory_notifier);
  69
  70 void unregister_memory_notifier(struct notifier_block *nb)
  71 {
  72         blocking_notifier_chain_unregister(&memory_chain, nb);
  73 }
  74 EXPORT_SYMBOL(unregister_memory_notifier);
  75
  76 static ATOMIC_NOTIFIER_HEAD(memory_isolate_chain);
  77
  78 int register_memory_isolate_notifier(struct notifier_block *nb)
  79 {
  80         return atomic_notifier_chain_register(&memory_isolate_chain, nb);
  81 }
  82 EXPORT_SYMBOL(register_memory_isolate_notifier);
  83
  84 void unregister_memory_isolate_notifier(struct notifier_block *nb)
  85 {
  86         atomic_notifier_chain_unregister(&memory_isolate_chain, nb);
  87 }
  88 EXPORT_SYMBOL(unregister_memory_isolate_notifier);
  89
  90 static void memory_block_release(struct device *dev)
  91 {
  92         struct memory_block *mem = to_memory_block(dev);
  93
  94         kfree(mem);
  95 }
  96
  97 unsigned long __weak memory_block_size_bytes(void)
  98 {
  99         return MIN_MEMORY_BLOCK_SIZE;
 100 }
 101 EXPORT_SYMBOL_GPL(memory_block_size_bytes);
 102
 103 /*
 104  * Show the first physical section index (number) of this memory block.
 105  */
 106 static ssize_t phys_index_show(struct device *dev,
 107                                struct device_attribute *attr, char *buf)
 108 {
 109         struct memory_block *mem = to_memory_block(dev);
 110         unsigned long phys_index;
 111
 112         phys_index = mem->start_section_nr / sections_per_block;
 113         return sprintf(buf, "%08lx\n", phys_index);
 114 }
 115
 116 /*
 117  * Show whether the memory block is likely to be offlineable (or is already
 118  * offline). Once offline, the memory block could be removed. The return
 119  * value does, however, not indicate that there is a way to remove the
 120  * memory block.
 121  */
 122 static ssize_t removable_show(struct device *dev, struct device_attribute *attr,
 123                               char *buf)
 124 {
 125         struct memory_block *mem = to_memory_block(dev);
 126         unsigned long pfn;
 127         int ret = 1, i;
 128
 129         if (mem->state != MEM_ONLINE)
 130                 goto out;
 131
 132         for (i = 0; i < sections_per_block; i++) {
 133                 if (!present_section_nr(mem->start_section_nr + i))
 134                         continue;
 135                 pfn = section_nr_to_pfn(mem->start_section_nr + i);
 136                 ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
 137         }
 138
 139 out:
 140         return sprintf(buf, "%d\n", ret);
 141 }
 142
 143 /*
 144  * online, offline, going offline, etc.
 145  */
 146 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 147                           char *buf)
 148 {
 149         struct memory_block *mem = to_memory_block(dev);
 150         ssize_t len = 0;
 151
 152         /*
 153          * We can probably put these states in a nice little array
 154          * so that they're not open-coded
 155          */
 156         switch (mem->state) {
 157         case MEM_ONLINE:
 158                 len = sprintf(buf, "online\n");
 159                 break;
 160         case MEM_OFFLINE:
 161                 len = sprintf(buf, "offline\n");
 162                 break;
 163         case MEM_GOING_OFFLINE:
 164                 len = sprintf(buf, "going-offline\n");
 165                 break;
 166         default:
 167                 len = sprintf(buf, "ERROR-UNKNOWN-%ld\n",
 168                                 mem->state);
 169                 WARN_ON(1);
 170                 break;
 171         }
 172
 173         return len;
 174 }
 175
 176 int memory_notify(unsigned long val, void *v)
 177 {
 178         return blocking_notifier_call_chain(&memory_chain, val, v);
 179 }
 180
 181 int memory_isolate_notify(unsigned long val, void *v)
 182 {
 183         return atomic_notifier_call_chain(&memory_isolate_chain, val, v);
 184 }
 185
 186 /*
 187  * The probe routines leave the pages uninitialized, just as the bootmem code
 188  * does. Make sure we do not access them, but instead use only information from
 189  * within sections.
 190  */
 191 static bool pages_correctly_probed(unsigned long start_pfn)
 192 {
 193         unsigned long section_nr = pfn_to_section_nr(start_pfn);
 194         unsigned long section_nr_end = section_nr + sections_per_block;
 195         unsigned long pfn = start_pfn;
 196
 197         /*
 198          * memmap between sections is not contiguous except with
 199          * SPARSEMEM_VMEMMAP. We lookup the page once per section
 200          * and assume memmap is contiguous within each section
 201          */
 202         for (; section_nr < section_nr_end; section_nr++) {
 203                 if (WARN_ON_ONCE(!pfn_valid(pfn)))
 204                         return false;
 205
 206                 if (!present_section_nr(section_nr)) {
 207                         pr_warn("section %ld pfn[%lx, %lx) not present\n",
 208                                 section_nr, pfn, pfn + PAGES_PER_SECTION);
 209                         return false;
 210                 } else if (!valid_section_nr(section_nr)) {
 211                         pr_warn("section %ld pfn[%lx, %lx) no valid memmap\n",
 212                                 section_nr, pfn, pfn + PAGES_PER_SECTION);
 213                         return false;
 214                 } else if (online_section_nr(section_nr)) {
 215                         pr_warn("section %ld pfn[%lx, %lx) is already online\n",
 216                                 section_nr, pfn, pfn + PAGES_PER_SECTION);
 217                         return false;
 218                 }
 219                 pfn += PAGES_PER_SECTION;
 220         }
 221
 222         return true;
 223 }
 224
 225 /*
 226  * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
 227  * OK to have direct references to sparsemem variables in here.
 228  */
 229 static int
 230 memory_block_action(unsigned long start_section_nr, unsigned long action,
 231                     int online_type)
 232 {
 233         unsigned long start_pfn;
 234         unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
 235         int ret;
 236
 237         start_pfn = section_nr_to_pfn(start_section_nr);
 238
 239         switch (action) {
 240         case MEM_ONLINE:
 241                 if (!pages_correctly_probed(start_pfn))
 242                         return -EBUSY;
 243
 244                 ret = online_pages(start_pfn, nr_pages, online_type);
 245                 break;
 246         case MEM_OFFLINE:
 247                 ret = offline_pages(start_pfn, nr_pages);
 248                 break;
 249         default:
 250                 WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
 251                      "%ld\n", __func__, start_section_nr, action, action);
 252                 ret = -EINVAL;
 253         }
 254
 255         return ret;
 256 }
 257
 258 static int memory_block_change_state(struct memory_block *mem,
 259                 unsigned long to_state, unsigned long from_state_req)
 260 {
 261         int ret = 0;
 262
 263         if (mem->state != from_state_req)
 264                 return -EINVAL;
 265
 266         if (to_state == MEM_OFFLINE)
 267                 mem->state = MEM_GOING_OFFLINE;
 268
 269         ret = memory_block_action(mem->start_section_nr, to_state,
 270                                 mem->online_type);
 271
 272         mem->state = ret ? from_state_req : to_state;
 273
 274         return ret;
 275 }
 276
 277 /* The device lock serializes operations on memory_subsys_[online|offline] */
 278 static int memory_subsys_online(struct device *dev)
 279 {
 280         struct memory_block *mem = to_memory_block(dev);
 281         int ret;
 282
 283         if (mem->state == MEM_ONLINE)
 284                 return 0;
 285
 286         /*
 287          * If we are called from state_store(), online_type will be
 288          * set >= 0 Otherwise we were called from the device online
 289          * attribute and need to set the online_type.
 290          */
 291         if (mem->online_type < 0)
 292                 mem->online_type = MMOP_ONLINE_KEEP;
 293
 294         ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
 295
 296         /* clear online_type */
 297         mem->online_type = -1;
 298
 299         return ret;
 300 }
 301
 302 static int memory_subsys_offline(struct device *dev)
 303 {
 304         struct memory_block *mem = to_memory_block(dev);
 305
 306         if (mem->state == MEM_OFFLINE)
 307                 return 0;
 308
 309         /* Can't offline block with non-present sections */
 310         if (mem->section_count != sections_per_block)
 311                 return -EINVAL;
 312
 313         return memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
 314 }
 315
 316 static ssize_t state_store(struct device *dev, struct device_attribute *attr,
 317                            const char *buf, size_t count)
 318 {
 319         struct memory_block *mem = to_memory_block(dev);
 320         int ret, online_type;
 321
 322         ret = lock_device_hotplug_sysfs();
 323         if (ret)
 324                 return ret;
 325
 326         if (sysfs_streq(buf, "online_kernel"))
 327                 online_type = MMOP_ONLINE_KERNEL;
 328         else if (sysfs_streq(buf, "online_movable"))
 329                 online_type = MMOP_ONLINE_MOVABLE;
 330         else if (sysfs_streq(buf, "online"))
 331                 online_type = MMOP_ONLINE_KEEP;
 332         else if (sysfs_streq(buf, "offline"))
 333                 online_type = MMOP_OFFLINE;
 334         else {
 335                 ret = -EINVAL;
 336                 goto err;
 337         }
 338
 339         switch (online_type) {
 340         case MMOP_ONLINE_KERNEL:
 341         case MMOP_ONLINE_MOVABLE:
 342         case MMOP_ONLINE_KEEP:
 343                 /* mem->online_type is protected by device_hotplug_lock */
 344                 mem->online_type = online_type;
 345                 ret = device_online(&mem->dev);
 346                 break;
 347         case MMOP_OFFLINE:
 348                 ret = device_offline(&mem->dev);
 349                 break;
 350         default:
 351                 ret = -EINVAL; /* should never happen */
 352         }
 353
 354 err:
 355         unlock_device_hotplug();
 356
 357         if (ret < 0)
 358                 return ret;
 359         if (ret)
 360                 return -EINVAL;
 361
 362         return count;
 363 }
 364
 365 /*
 366  * phys_device is a bad name for this.  What I really want
 367  * is a way to differentiate between memory ranges that
 368  * are part of physical devices that constitute
 369  * a complete removable unit or fru.
 370  * i.e. do these ranges belong to the same physical device,
 371  * s.t. if I offline all of these sections I can then
 372  * remove the physical device?
 373  */
 374 static ssize_t phys_device_show(struct device *dev,
 375                                 struct device_attribute *attr, char *buf)
 376 {
 377         struct memory_block *mem = to_memory_block(dev);
 378         return sprintf(buf, "%d\n", mem->phys_device);
 379 }
 380
 381 #ifdef CONFIG_MEMORY_HOTREMOVE
 382 static void print_allowed_zone(char *buf, int nid, unsigned long start_pfn,
 383                 unsigned long nr_pages, int online_type,
 384                 struct zone *default_zone)
 385 {
 386         struct zone *zone;
 387
 388         zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
 389         if (zone != default_zone) {
 390                 strcat(buf, " ");
 391                 strcat(buf, zone->name);
 392         }
 393 }
 394
 395 static ssize_t valid_zones_show(struct device *dev,
 396                                 struct device_attribute *attr, char *buf)
 397 {
 398         struct memory_block *mem = to_memory_block(dev);
 399         unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
 400         unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
 401         unsigned long valid_start_pfn, valid_end_pfn;
 402         struct zone *default_zone;
 403         int nid;
 404
 405         /*
 406          * Check the existing zone. Make sure that we do that only on the
 407          * online nodes otherwise the page_zone is not reliable
 408          */
 409         if (mem->state == MEM_ONLINE) {
 410                 /*
 411                  * The block contains more than one zone can not be offlined.
 412                  * This can happen e.g. for ZONE_DMA and ZONE_DMA32
 413                  */
 414                 if (!test_pages_in_a_zone(start_pfn, start_pfn + nr_pages,
 415                                           &valid_start_pfn, &valid_end_pfn))
 416                         return sprintf(buf, "none\n");
 417                 start_pfn = valid_start_pfn;
 418                 strcat(buf, page_zone(pfn_to_page(start_pfn))->name);
 419                 goto out;
 420         }
 421
 422         nid = mem->nid;
 423         default_zone = zone_for_pfn_range(MMOP_ONLINE_KEEP, nid, start_pfn, nr_pages);
 424         strcat(buf, default_zone->name);
 425
 426         print_allowed_zone(buf, nid, start_pfn, nr_pages, MMOP_ONLINE_KERNEL,
 427                         default_zone);
 428         print_allowed_zone(buf, nid, start_pfn, nr_pages, MMOP_ONLINE_MOVABLE,
 429                         default_zone);
 430 out:
 431         strcat(buf, "\n");
 432
 433         return strlen(buf);
 434 }
 435 static DEVICE_ATTR_RO(valid_zones);
 436 #endif
 437
 438 static DEVICE_ATTR_RO(phys_index);
 439 static DEVICE_ATTR_RW(state);
 440 static DEVICE_ATTR_RO(phys_device);
 441 static DEVICE_ATTR_RO(removable);
 442
 443 /*
 444  * Show the memory block size (shared by all memory blocks).
 445  */
 446 static ssize_t block_size_bytes_show(struct device *dev,
 447                                      struct device_attribute *attr, char *buf)
 448 {
 449         return sprintf(buf, "%lx\n", memory_block_size_bytes());
 450 }
 451
 452 static DEVICE_ATTR_RO(block_size_bytes);
 453
 454 /*
 455  * Memory auto online policy.
 456  */
 457
 458 static ssize_t auto_online_blocks_show(struct device *dev,
 459                                        struct device_attribute *attr, char *buf)
 460 {
 461         if (memhp_auto_online)
 462                 return sprintf(buf, "online\n");
 463         else
 464                 return sprintf(buf, "offline\n");
 465 }
 466
 467 static ssize_t auto_online_blocks_store(struct device *dev,
 468                                         struct device_attribute *attr,
 469                                         const char *buf, size_t count)
 470 {
 471         if (sysfs_streq(buf, "online"))
 472                 memhp_auto_online = true;
 473         else if (sysfs_streq(buf, "offline"))
 474                 memhp_auto_online = false;
 475         else
 476                 return -EINVAL;
 477
 478         return count;
 479 }
 480
 481 static DEVICE_ATTR_RW(auto_online_blocks);
 482
 483 /*
 484  * Some architectures will have custom drivers to do this, and
 485  * will not need to do it from userspace.  The fake hot-add code
 486  * as well as ppc64 will do all of their discovery in userspace
 487  * and will require this interface.
 488  */
 489 #ifdef CONFIG_ARCH_MEMORY_PROBE
 490 static ssize_t probe_store(struct device *dev, struct device_attribute *attr,
 491                            const char *buf, size_t count)
 492 {
 493         u64 phys_addr;
 494         int nid, ret;
 495         unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;
 496
 497         ret = kstrtoull(buf, 0, &phys_addr);
 498         if (ret)
 499                 return ret;
 500
 501         if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
 502                 return -EINVAL;
 503
 504         ret = lock_device_hotplug_sysfs();
 505         if (ret)
 506                 return ret;
 507
 508         nid = memory_add_physaddr_to_nid(phys_addr);
 509         ret = __add_memory(nid, phys_addr,
 510                            MIN_MEMORY_BLOCK_SIZE * sections_per_block);
 511
 512         if (ret)
 513                 goto out;
 514
 515         ret = count;
 516 out:
 517         unlock_device_hotplug();
 518         return ret;
 519 }
 520
 521 static DEVICE_ATTR_WO(probe);
 522 #endif
 523
 524 #ifdef CONFIG_MEMORY_FAILURE
 525 /*
 526  * Support for offlining pages of memory
 527  */
 528
 529 /* Soft offline a page */
 530 static ssize_t soft_offline_page_store(struct device *dev,
 531                                        struct device_attribute *attr,
 532                                        const char *buf, size_t count)
 533 {
 534         int ret;
 535         u64 pfn;
 536         if (!capable(CAP_SYS_ADMIN))
 537                 return -EPERM;
 538         if (kstrtoull(buf, 0, &pfn) < 0)
 539                 return -EINVAL;
 540         pfn >>= PAGE_SHIFT;
 541         if (!pfn_valid(pfn))
 542                 return -ENXIO;
 543         /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
 544         if (!pfn_to_online_page(pfn))
 545                 return -EIO;
 546         ret = soft_offline_page(pfn_to_page(pfn), 0);
 547         return ret == 0 ? count : ret;
 548 }
 549
 550 /* Forcibly offline a page, including killing processes. */
 551 static ssize_t hard_offline_page_store(struct device *dev,
 552                                        struct device_attribute *attr,
 553                                        const char *buf, size_t count)
 554 {
 555         int ret;
 556         u64 pfn;
 557         if (!capable(CAP_SYS_ADMIN))
 558                 return -EPERM;
 559         if (kstrtoull(buf, 0, &pfn) < 0)
 560                 return -EINVAL;
 561         pfn >>= PAGE_SHIFT;
 562         ret = memory_failure(pfn, 0);
 563         return ret ? ret : count;
 564 }
 565
 566 static DEVICE_ATTR_WO(soft_offline_page);
 567 static DEVICE_ATTR_WO(hard_offline_page);
 568 #endif
 569
 570 /*
 571  * Note that phys_device is optional.  It is here to allow for
 572  * differentiation between which *physical* devices each
 573  * section belongs to...
 574  */
 575 int __weak arch_get_memory_phys_device(unsigned long start_pfn)
 576 {
 577         return 0;
 578 }
 579
 580 /* A reference for the returned memory block device is acquired. */
 581 static struct memory_block *find_memory_block_by_id(unsigned long block_id)
 582 {
 583         struct device *dev;
 584
 585         dev = subsys_find_device_by_id(&memory_subsys, block_id, NULL);
 586         return dev ? to_memory_block(dev) : NULL;
 587 }
 588
 589 /*
 590  * For now, we have a linear search to go find the appropriate
 591  * memory_block corresponding to a particular phys_index. If
 592  * this gets to be a real problem, we can always use a radix
 593  * tree or something here.
 594  *
 595  * This could be made generic for all device subsystems.
 596  */
 597 struct memory_block *find_memory_block(struct mem_section *section)
 598 {
 599         unsigned long block_id = base_memory_block_id(__section_nr(section));
 600
 601         return find_memory_block_by_id(block_id);
 602 }
 603
 604 static struct attribute *memory_memblk_attrs[] = {
 605         &dev_attr_phys_index.attr,
 606         &dev_attr_state.attr,
 607         &dev_attr_phys_device.attr,
 608         &dev_attr_removable.attr,
 609 #ifdef CONFIG_MEMORY_HOTREMOVE
 610         &dev_attr_valid_zones.attr,
 611 #endif
 612         NULL
 613 };
 614
 615 static struct attribute_group memory_memblk_attr_group = {
 616         .attrs = memory_memblk_attrs,
 617 };
 618
 619 static const struct attribute_group *memory_memblk_attr_groups[] = {
 620         &memory_memblk_attr_group,
 621         NULL,
 622 };
 623
 624 /*
 625  * register_memory - Setup a sysfs device for a memory block
 626  */
 627 static
 628 int register_memory(struct memory_block *memory)
 629 {
 630         int ret;
 631
 632         memory->dev.bus = &memory_subsys;
 633         memory->dev.id = memory->start_section_nr / sections_per_block;
 634         memory->dev.release = memory_block_release;
 635         memory->dev.groups = memory_memblk_attr_groups;
 636         memory->dev.offline = memory->state == MEM_OFFLINE;
 637
 638         ret = device_register(&memory->dev);
 639         if (ret)
 640                 put_device(&memory->dev);
 641
 642         return ret;
 643 }
 644
 645 static int init_memory_block(struct memory_block **memory,
 646                              unsigned long block_id, unsigned long state)
 647 {
 648         struct memory_block *mem;
 649         unsigned long start_pfn;
 650         int ret = 0;
 651
 652         mem = find_memory_block_by_id(block_id);
 653         if (mem) {
 654                 put_device(&mem->dev);
 655                 return -EEXIST;
 656         }
 657         mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 658         if (!mem)
 659                 return -ENOMEM;
 660
 661         mem->start_section_nr = block_id * sections_per_block;
 662         mem->state = state;
 663         start_pfn = section_nr_to_pfn(mem->start_section_nr);
 664         mem->phys_device = arch_get_memory_phys_device(start_pfn);
 665         mem->nid = NUMA_NO_NODE;
 666
 667         ret = register_memory(mem);
 668
 669         *memory = mem;
 670         return ret;
 671 }
 672
 673 static int add_memory_block(unsigned long base_section_nr)
 674 {
 675         int ret, section_count = 0;
 676         struct memory_block *mem;
 677         unsigned long nr;
 678
 679         for (nr = base_section_nr; nr < base_section_nr + sections_per_block;
 680              nr++)
 681                 if (present_section_nr(nr))
 682                         section_count++;
 683
 684         if (section_count == 0)
 685                 return 0;
 686         ret = init_memory_block(&mem, base_memory_block_id(base_section_nr),
 687                                 MEM_ONLINE);
 688         if (ret)
 689                 return ret;
 690         mem->section_count = section_count;
 691         return 0;
 692 }
 693
 694 static void unregister_memory(struct memory_block *memory)
 695 {
 696         if (WARN_ON_ONCE(memory->dev.bus != &memory_subsys))
 697                 return;
 698
 699         /* drop the ref. we got via find_memory_block() */
 700         put_device(&memory->dev);
 701         device_unregister(&memory->dev);
 702 }
 703
 704 /*
 705  * Create memory block devices for the given memory area. Start and size
 706  * have to be aligned to memory block granularity. Memory block devices
 707  * will be initialized as offline.
 708  */
 709 int create_memory_block_devices(unsigned long start, unsigned long size)
 710 {
 711         const unsigned long start_block_id = pfn_to_block_id(PFN_DOWN(start));
 712         unsigned long end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
 713         struct memory_block *mem;
 714         unsigned long block_id;
 715         int ret = 0;
 716
 717         if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) ||
 718                          !IS_ALIGNED(size, memory_block_size_bytes())))
 719                 return -EINVAL;
 720
 721         mutex_lock(&mem_sysfs_mutex);
 722         for (block_id = start_block_id; block_id != end_block_id; block_id++) {
 723                 ret = init_memory_block(&mem, block_id, MEM_OFFLINE);
 724                 if (ret)
 725                         break;
 726                 mem->section_count = sections_per_block;
 727         }
 728         if (ret) {
 729                 end_block_id = block_id;
 730                 for (block_id = start_block_id; block_id != end_block_id;
 731                      block_id++) {
 732                         mem = find_memory_block_by_id(block_id);
 733                         mem->section_count = 0;
 734                         unregister_memory(mem);
 735                 }
 736         }
 737         mutex_unlock(&mem_sysfs_mutex);
 738         return ret;
 739 }
 740
 741 /*
 742  * Remove memory block devices for the given memory area. Start and size
 743  * have to be aligned to memory block granularity. Memory block devices
 744  * have to be offline.
 745  */
 746 void remove_memory_block_devices(unsigned long start, unsigned long size)
 747 {
 748         const unsigned long start_block_id = pfn_to_block_id(PFN_DOWN(start));
 749         const unsigned long end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
 750         struct memory_block *mem;
 751         unsigned long block_id;
 752
 753         if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) ||
 754                          !IS_ALIGNED(size, memory_block_size_bytes())))
 755                 return;
 756
 757         mutex_lock(&mem_sysfs_mutex);
 758         for (block_id = start_block_id; block_id != end_block_id; block_id++) {
 759                 mem = find_memory_block_by_id(block_id);
 760                 if (WARN_ON_ONCE(!mem))
 761                         continue;
 762                 mem->section_count = 0;
 763                 unregister_memory_block_under_nodes(mem);
 764                 unregister_memory(mem);
 765         }
 766         mutex_unlock(&mem_sysfs_mutex);
 767 }
 768
 769 /* return true if the memory block is offlined, otherwise, return false */
 770 bool is_memblock_offlined(struct memory_block *mem)
 771 {
 772         return mem->state == MEM_OFFLINE;
 773 }
 774
 775 static struct attribute *memory_root_attrs[] = {
 776 #ifdef CONFIG_ARCH_MEMORY_PROBE
 777         &dev_attr_probe.attr,
 778 #endif
 779
 780 #ifdef CONFIG_MEMORY_FAILURE
 781         &dev_attr_soft_offline_page.attr,
 782         &dev_attr_hard_offline_page.attr,
 783 #endif
 784
 785         &dev_attr_block_size_bytes.attr,
 786         &dev_attr_auto_online_blocks.attr,
 787         NULL
 788 };
 789
 790 static struct attribute_group memory_root_attr_group = {
 791         .attrs = memory_root_attrs,
 792 };
 793
 794 static const struct attribute_group *memory_root_attr_groups[] = {
 795         &memory_root_attr_group,
 796         NULL,
 797 };
 798
 799 /*
 800  * Initialize the sysfs support for memory devices...
 801  */
 802 void __init memory_dev_init(void)
 803 {
 804         int ret;
 805         int err;
 806         unsigned long block_sz, nr;
 807
 808         /* Validate the configured memory block size */
 809         block_sz = memory_block_size_bytes();
 810         if (!is_power_of_2(block_sz) || block_sz < MIN_MEMORY_BLOCK_SIZE)
 811                 panic("Memory block size not suitable: 0x%lx\n", block_sz);
 812         sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
 813
 814         ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
 815         if (ret)
 816                 goto out;
 817
 818         /*
 819          * Create entries for memory sections that were found
 820          * during boot and have been initialized
 821          */
 822         mutex_lock(&mem_sysfs_mutex);
 823         for (nr = 0; nr <= __highest_present_section_nr;
 824              nr += sections_per_block) {
 825                 err = add_memory_block(nr);
 826                 if (!ret)
 827                         ret = err;
 828         }
 829         mutex_unlock(&mem_sysfs_mutex);
 830
 831 out:
 832         if (ret)
 833                 panic("%s() failed: %d\n", __func__, ret);
 834 }
 835
 836 /**
 837  * walk_memory_blocks - walk through all present memory blocks overlapped
 838  *                      by the range [start, start + size)
 839  *
 840  * @start: start address of the memory range
 841  * @size: size of the memory range
 842  * @arg: argument passed to func
 843  * @func: callback for each memory section walked
 844  *
 845  * This function walks through all present memory blocks overlapped by the
 846  * range [start, start + size), calling func on each memory block.
 847  *
 848  * In case func() returns an error, walking is aborted and the error is
 849  * returned.
 850  */
 851 int walk_memory_blocks(unsigned long start, unsigned long size,
 852                        void *arg, walk_memory_blocks_func_t func)
 853 {
 854         const unsigned long start_block_id = phys_to_block_id(start);
 855         const unsigned long end_block_id = phys_to_block_id(start + size - 1);
 856         struct memory_block *mem;
 857         unsigned long block_id;
 858         int ret = 0;
 859
 860         if (!size)
 861                 return 0;
 862
 863         for (block_id = start_block_id; block_id <= end_block_id; block_id++) {
 864                 mem = find_memory_block_by_id(block_id);
 865                 if (!mem)
 866                         continue;
 867
 868                 ret = func(mem, arg);
 869                 put_device(&mem->dev);
 870                 if (ret)
 871                         break;
 872         }
 873         return ret;
 874 }