drivers/firmware/memmap.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/drivers/firmware/memmap.c
   4  *  Copyright (C) 2008 SUSE LINUX Products GmbH
   5  *  by Bernhard Walle <bernhard.walle@gmx.de>
   6  */
   7
   8 #include <linux/string.h>
   9 #include <linux/firmware-map.h>
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/types.h>
  13 #include <linux/memblock.h>
  14 #include <linux/slab.h>
  15 #include <linux/mm.h>
  16
  17 /*
  18  * Data types ------------------------------------------------------------------
  19  */
  20
  21 /*
  22  * Firmware map entry. Because firmware memory maps are flat and not
  23  * hierarchical, it's ok to organise them in a linked list. No parent
  24  * information is necessary as for the resource tree.
  25  */
  26 struct firmware_map_entry {
  27         /*
  28          * start and end must be u64 rather than resource_size_t, because e820
  29          * resources can lie at addresses above 4G.
  30          */
  31         u64                     start;  /* start of the memory range */
  32         u64                     end;    /* end of the memory range (incl.) */
  33         const char              *type;  /* type of the memory range */
  34         struct list_head        list;   /* entry for the linked list */
  35         struct kobject          kobj;   /* kobject for each entry */
  36 };
  37
  38 /*
  39  * Forward declarations --------------------------------------------------------
  40  */
  41 static ssize_t memmap_attr_show(struct kobject *kobj,
  42                                 struct attribute *attr, char *buf);
  43 static ssize_t start_show(struct firmware_map_entry *entry, char *buf);
  44 static ssize_t end_show(struct firmware_map_entry *entry, char *buf);
  45 static ssize_t type_show(struct firmware_map_entry *entry, char *buf);
  46
  47 static struct firmware_map_entry * __meminit
  48 firmware_map_find_entry(u64 start, u64 end, const char *type);
  49
  50 /*
  51  * Static data -----------------------------------------------------------------
  52  */
  53
  54 struct memmap_attribute {
  55         struct attribute attr;
  56         ssize_t (*show)(struct firmware_map_entry *entry, char *buf);
  57 };
  58
  59 static struct memmap_attribute memmap_start_attr = __ATTR_RO(start);
  60 static struct memmap_attribute memmap_end_attr   = __ATTR_RO(end);
  61 static struct memmap_attribute memmap_type_attr  = __ATTR_RO(type);
  62
  63 /*
  64  * These are default attributes that are added for every memmap entry.
  65  */
  66 static struct attribute *def_attrs[] = {
  67         &memmap_start_attr.attr,
  68         &memmap_end_attr.attr,
  69         &memmap_type_attr.attr,
  70         NULL
  71 };
  72
  73 static const struct sysfs_ops memmap_attr_ops = {
  74         .show = memmap_attr_show,
  75 };
  76
  77 /* Firmware memory map entries. */
  78 static LIST_HEAD(map_entries);
  79 static DEFINE_SPINLOCK(map_entries_lock);
  80
  81 /*
  82  * For memory hotplug, there is no way to free memory map entries allocated
  83  * by boot mem after the system is up. So when we hot-remove memory whose
  84  * map entry is allocated by bootmem, we need to remember the storage and
  85  * reuse it when the memory is hot-added again.
  86  */
  87 static LIST_HEAD(map_entries_bootmem);
  88 static DEFINE_SPINLOCK(map_entries_bootmem_lock);
  89
  90
  91 static inline struct firmware_map_entry *
  92 to_memmap_entry(struct kobject *kobj)
  93 {
  94         return container_of(kobj, struct firmware_map_entry, kobj);
  95 }
  96
  97 static void __meminit release_firmware_map_entry(struct kobject *kobj)
  98 {
  99         struct firmware_map_entry *entry = to_memmap_entry(kobj);
 100
 101         if (PageReserved(virt_to_page(entry))) {
 102                 /*
 103                  * Remember the storage allocated by bootmem, and reuse it when
 104                  * the memory is hot-added again. The entry will be added to
 105                  * map_entries_bootmem here, and deleted from &map_entries in
 106                  * firmware_map_remove_entry().
 107                  */
 108                 spin_lock(&map_entries_bootmem_lock);
 109                 list_add(&entry->list, &map_entries_bootmem);
 110                 spin_unlock(&map_entries_bootmem_lock);
 111
 112                 return;
 113         }
 114
 115         kfree(entry);
 116 }
 117
 118 static struct kobj_type __refdata memmap_ktype = {
 119         .release        = release_firmware_map_entry,
 120         .sysfs_ops      = &memmap_attr_ops,
 121         .default_attrs  = def_attrs,
 122 };
 123
 124 /*
 125  * Registration functions ------------------------------------------------------
 126  */
 127
 128 /**
 129  * firmware_map_add_entry() - Does the real work to add a firmware memmap entry.
 130  * @start: Start of the memory range.
 131  * @end:   End of the memory range (exclusive).
 132  * @type:  Type of the memory range.
 133  * @entry: Pre-allocated (either kmalloc() or bootmem allocator), uninitialised
 134  *         entry.
 135  *
 136  * Common implementation of firmware_map_add() and firmware_map_add_early()
 137  * which expects a pre-allocated struct firmware_map_entry.
 138  *
 139  * Return: 0 always
 140  */
 141 static int firmware_map_add_entry(u64 start, u64 end,
 142                                   const char *type,
 143                                   struct firmware_map_entry *entry)
 144 {
 145         BUG_ON(start > end);
 146
 147         entry->start = start;
 148         entry->end = end - 1;
 149         entry->type = type;
 150         INIT_LIST_HEAD(&entry->list);
 151         kobject_init(&entry->kobj, &memmap_ktype);
 152
 153         spin_lock(&map_entries_lock);
 154         list_add_tail(&entry->list, &map_entries);
 155         spin_unlock(&map_entries_lock);
 156
 157         return 0;
 158 }
 159
 160 /**
 161  * firmware_map_remove_entry() - Does the real work to remove a firmware
 162  * memmap entry.
 163  * @entry: removed entry.
 164  *
 165  * The caller must hold map_entries_lock, and release it properly.
 166  */
 167 static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
 168 {
 169         list_del(&entry->list);
 170 }
 171
 172 /*
 173  * Add memmap entry on sysfs
 174  */
 175 static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry)
 176 {
 177         static int map_entries_nr;
 178         static struct kset *mmap_kset;
 179
 180         if (entry->kobj.state_in_sysfs)
 181                 return -EEXIST;
 182
 183         if (!mmap_kset) {
 184                 mmap_kset = kset_create_and_add("memmap", NULL, firmware_kobj);
 185                 if (!mmap_kset)
 186                         return -ENOMEM;
 187         }
 188
 189         entry->kobj.kset = mmap_kset;
 190         if (kobject_add(&entry->kobj, NULL, "%d", map_entries_nr++))
 191                 kobject_put(&entry->kobj);
 192
 193         return 0;
 194 }
 195
 196 /*
 197  * Remove memmap entry on sysfs
 198  */
 199 static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
 200 {
 201         kobject_put(&entry->kobj);
 202 }
 203
 204 /**
 205  * firmware_map_find_entry_in_list() - Search memmap entry in a given list.
 206  * @start: Start of the memory range.
 207  * @end:   End of the memory range (exclusive).
 208  * @type:  Type of the memory range.
 209  * @list:  In which to find the entry.
 210  *
 211  * This function is to find the memmap entey of a given memory range in a
 212  * given list. The caller must hold map_entries_lock, and must not release
 213  * the lock until the processing of the returned entry has completed.
 214  *
 215  * Return: Pointer to the entry to be found on success, or NULL on failure.
 216  */
 217 static struct firmware_map_entry * __meminit
 218 firmware_map_find_entry_in_list(u64 start, u64 end, const char *type,
 219                                 struct list_head *list)
 220 {
 221         struct firmware_map_entry *entry;
 222
 223         list_for_each_entry(entry, list, list)
 224                 if ((entry->start == start) && (entry->end == end) &&
 225                     (!strcmp(entry->type, type))) {
 226                         return entry;
 227                 }
 228
 229         return NULL;
 230 }
 231
 232 /**
 233  * firmware_map_find_entry() - Search memmap entry in map_entries.
 234  * @start: Start of the memory range.
 235  * @end:   End of the memory range (exclusive).
 236  * @type:  Type of the memory range.
 237  *
 238  * This function is to find the memmap entey of a given memory range.
 239  * The caller must hold map_entries_lock, and must not release the lock
 240  * until the processing of the returned entry has completed.
 241  *
 242  * Return: Pointer to the entry to be found on success, or NULL on failure.
 243  */
 244 static struct firmware_map_entry * __meminit
 245 firmware_map_find_entry(u64 start, u64 end, const char *type)
 246 {
 247         return firmware_map_find_entry_in_list(start, end, type, &map_entries);
 248 }
 249
 250 /**
 251  * firmware_map_find_entry_bootmem() - Search memmap entry in map_entries_bootmem.
 252  * @start: Start of the memory range.
 253  * @end:   End of the memory range (exclusive).
 254  * @type:  Type of the memory range.
 255  *
 256  * This function is similar to firmware_map_find_entry except that it find the
 257  * given entry in map_entries_bootmem.
 258  *
 259  * Return: Pointer to the entry to be found on success, or NULL on failure.
 260  */
 261 static struct firmware_map_entry * __meminit
 262 firmware_map_find_entry_bootmem(u64 start, u64 end, const char *type)
 263 {
 264         return firmware_map_find_entry_in_list(start, end, type,
 265                                                &map_entries_bootmem);
 266 }
 267
 268 /**
 269  * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
 270  * memory hotplug.
 271  * @start: Start of the memory range.
 272  * @end:   End of the memory range (exclusive)
 273  * @type:  Type of the memory range.
 274  *
 275  * Adds a firmware mapping entry. This function is for memory hotplug, it is
 276  * similar to function firmware_map_add_early(). The only difference is that
 277  * it will create the syfs entry dynamically.
 278  *
 279  * Return: 0 on success, or -ENOMEM if no memory could be allocated.
 280  */
 281 int __meminit firmware_map_add_hotplug(u64 start, u64 end, const char *type)
 282 {
 283         struct firmware_map_entry *entry;
 284
 285         entry = firmware_map_find_entry(start, end - 1, type);
 286         if (entry)
 287                 return 0;
 288
 289         entry = firmware_map_find_entry_bootmem(start, end - 1, type);
 290         if (!entry) {
 291                 entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
 292                 if (!entry)
 293                         return -ENOMEM;
 294         } else {
 295                 /* Reuse storage allocated by bootmem. */
 296                 spin_lock(&map_entries_bootmem_lock);
 297                 list_del(&entry->list);
 298                 spin_unlock(&map_entries_bootmem_lock);
 299
 300                 memset(entry, 0, sizeof(*entry));
 301         }
 302
 303         firmware_map_add_entry(start, end, type, entry);
 304         /* create the memmap entry */
 305         add_sysfs_fw_map_entry(entry);
 306
 307         return 0;
 308 }
 309
 310 /**
 311  * firmware_map_add_early() - Adds a firmware mapping entry.
 312  * @start: Start of the memory range.
 313  * @end:   End of the memory range.
 314  * @type:  Type of the memory range.
 315  *
 316  * Adds a firmware mapping entry. This function uses the bootmem allocator
 317  * for memory allocation.
 318  *
 319  * That function must be called before late_initcall.
 320  *
 321  * Return: 0 on success, or -ENOMEM if no memory could be allocated.
 322  */
 323 int __init firmware_map_add_early(u64 start, u64 end, const char *type)
 324 {
 325         struct firmware_map_entry *entry;
 326
 327         entry = memblock_alloc(sizeof(struct firmware_map_entry),
 328                                SMP_CACHE_BYTES);
 329         if (WARN_ON(!entry))
 330                 return -ENOMEM;
 331
 332         return firmware_map_add_entry(start, end, type, entry);
 333 }
 334
 335 /**
 336  * firmware_map_remove() - remove a firmware mapping entry
 337  * @start: Start of the memory range.
 338  * @end:   End of the memory range.
 339  * @type:  Type of the memory range.
 340  *
 341  * removes a firmware mapping entry.
 342  *
 343  * Return: 0 on success, or -EINVAL if no entry.
 344  */
 345 int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
 346 {
 347         struct firmware_map_entry *entry;
 348
 349         spin_lock(&map_entries_lock);
 350         entry = firmware_map_find_entry(start, end - 1, type);
 351         if (!entry) {
 352                 spin_unlock(&map_entries_lock);
 353                 return -EINVAL;
 354         }
 355
 356         firmware_map_remove_entry(entry);
 357         spin_unlock(&map_entries_lock);
 358
 359         /* remove the memmap entry */
 360         remove_sysfs_fw_map_entry(entry);
 361
 362         return 0;
 363 }
 364
 365 /*
 366  * Sysfs functions -------------------------------------------------------------
 367  */
 368
 369 static ssize_t start_show(struct firmware_map_entry *entry, char *buf)
 370 {
 371         return snprintf(buf, PAGE_SIZE, "0x%llx\n",
 372                 (unsigned long long)entry->start);
 373 }
 374
 375 static ssize_t end_show(struct firmware_map_entry *entry, char *buf)
 376 {
 377         return snprintf(buf, PAGE_SIZE, "0x%llx\n",
 378                 (unsigned long long)entry->end);
 379 }
 380
 381 static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
 382 {
 383         return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
 384 }
 385
 386 static inline struct memmap_attribute *to_memmap_attr(struct attribute *attr)
 387 {
 388         return container_of(attr, struct memmap_attribute, attr);
 389 }
 390
 391 static ssize_t memmap_attr_show(struct kobject *kobj,
 392                                 struct attribute *attr, char *buf)
 393 {
 394         struct firmware_map_entry *entry = to_memmap_entry(kobj);
 395         struct memmap_attribute *memmap_attr = to_memmap_attr(attr);
 396
 397         return memmap_attr->show(entry, buf);
 398 }
 399
 400 /*
 401  * Initialises stuff and adds the entries in the map_entries list to
 402  * sysfs. Important is that firmware_map_add() and firmware_map_add_early()
 403  * must be called before late_initcall. That's just because that function
 404  * is called as late_initcall() function, which means that if you call
 405  * firmware_map_add() or firmware_map_add_early() afterwards, the entries
 406  * are not added to sysfs.
 407  */
 408 static int __init firmware_memmap_init(void)
 409 {
 410         struct firmware_map_entry *entry;
 411
 412         list_for_each_entry(entry, &map_entries, list)
 413                 add_sysfs_fw_map_entry(entry);
 414
 415         return 0;
 416 }
 417 late_initcall(firmware_memmap_init);
 418