drivers/firmware/memmap.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * linux/drivers/firmware/memmap.c
0004  *  Copyright (C) 2008 SUSE LINUX Products GmbH
0005  *  by Bernhard Walle <bernhard.walle@gmx.de>
0006  */
0007
0008 #include <linux/string.h>
0009 #include <linux/firmware-map.h>
0010 #include <linux/kernel.h>
0011 #include <linux/module.h>
0012 #include <linux/types.h>
0013 #include <linux/memblock.h>
0014 #include <linux/slab.h>
0015 #include <linux/mm.h>
0016
0017 /*
0018  * Data types ------------------------------------------------------------------
0019  */
0020
0021 /*
0022  * Firmware map entry. Because firmware memory maps are flat and not
0023  * hierarchical, it's ok to organise them in a linked list. No parent
0024  * information is necessary as for the resource tree.
0025  */
0026 struct firmware_map_entry {
0027     /*
0028      * start and end must be u64 rather than resource_size_t, because e820
0029      * resources can lie at addresses above 4G.
0030      */
0031     u64         start;  /* start of the memory range */
0032     u64         end;    /* end of the memory range (incl.) */
0033     const char      *type;  /* type of the memory range */
0034     struct list_head    list;   /* entry for the linked list */
0035     struct kobject      kobj;   /* kobject for each entry */
0036 };
0037
0038 /*
0039  * Forward declarations --------------------------------------------------------
0040  */
0041 static ssize_t memmap_attr_show(struct kobject *kobj,
0042                 struct attribute *attr, char *buf);
0043 static ssize_t start_show(struct firmware_map_entry *entry, char *buf);
0044 static ssize_t end_show(struct firmware_map_entry *entry, char *buf);
0045 static ssize_t type_show(struct firmware_map_entry *entry, char *buf);
0046
0047 static struct firmware_map_entry * __meminit
0048 firmware_map_find_entry(u64 start, u64 end, const char *type);
0049
0050 /*
0051  * Static data -----------------------------------------------------------------
0052  */
0053
0054 struct memmap_attribute {
0055     struct attribute attr;
0056     ssize_t (*show)(struct firmware_map_entry *entry, char *buf);
0057 };
0058
0059 static struct memmap_attribute memmap_start_attr = __ATTR_RO(start);
0060 static struct memmap_attribute memmap_end_attr   = __ATTR_RO(end);
0061 static struct memmap_attribute memmap_type_attr  = __ATTR_RO(type);
0062
0063 /*
0064  * These are default attributes that are added for every memmap entry.
0065  */
0066 static struct attribute *def_attrs[] = {
0067     &memmap_start_attr.attr,
0068     &memmap_end_attr.attr,
0069     &memmap_type_attr.attr,
0070     NULL
0071 };
0072 ATTRIBUTE_GROUPS(def);
0073
0074 static const struct sysfs_ops memmap_attr_ops = {
0075     .show = memmap_attr_show,
0076 };
0077
0078 /* Firmware memory map entries. */
0079 static LIST_HEAD(map_entries);
0080 static DEFINE_SPINLOCK(map_entries_lock);
0081
0082 /*
0083  * For memory hotplug, there is no way to free memory map entries allocated
0084  * by boot mem after the system is up. So when we hot-remove memory whose
0085  * map entry is allocated by bootmem, we need to remember the storage and
0086  * reuse it when the memory is hot-added again.
0087  */
0088 static LIST_HEAD(map_entries_bootmem);
0089 static DEFINE_SPINLOCK(map_entries_bootmem_lock);
0090
0091
0092 static inline struct firmware_map_entry *
0093 to_memmap_entry(struct kobject *kobj)
0094 {
0095     return container_of(kobj, struct firmware_map_entry, kobj);
0096 }
0097
0098 static void __meminit release_firmware_map_entry(struct kobject *kobj)
0099 {
0100     struct firmware_map_entry *entry = to_memmap_entry(kobj);
0101
0102     if (PageReserved(virt_to_page(entry))) {
0103         /*
0104          * Remember the storage allocated by bootmem, and reuse it when
0105          * the memory is hot-added again. The entry will be added to
0106          * map_entries_bootmem here, and deleted from &map_entries in
0107          * firmware_map_remove_entry().
0108          */
0109         spin_lock(&map_entries_bootmem_lock);
0110         list_add(&entry->list, &map_entries_bootmem);
0111         spin_unlock(&map_entries_bootmem_lock);
0112
0113         return;
0114     }
0115
0116     kfree(entry);
0117 }
0118
0119 static struct kobj_type __refdata memmap_ktype = {
0120     .release    = release_firmware_map_entry,
0121     .sysfs_ops  = &memmap_attr_ops,
0122     .default_groups = def_groups,
0123 };
0124
0125 /*
0126  * Registration functions ------------------------------------------------------
0127  */
0128
0129 /**
0130  * firmware_map_add_entry() - Does the real work to add a firmware memmap entry.
0131  * @start: Start of the memory range.
0132  * @end:   End of the memory range (exclusive).
0133  * @type:  Type of the memory range.
0134  * @entry: Pre-allocated (either kmalloc() or bootmem allocator), uninitialised
0135  *         entry.
0136  *
0137  * Common implementation of firmware_map_add() and firmware_map_add_early()
0138  * which expects a pre-allocated struct firmware_map_entry.
0139  *
0140  * Return: 0 always
0141  */
0142 static int firmware_map_add_entry(u64 start, u64 end,
0143                   const char *type,
0144                   struct firmware_map_entry *entry)
0145 {
0146     BUG_ON(start > end);
0147
0148     entry->start = start;
0149     entry->end = end - 1;
0150     entry->type = type;
0151     INIT_LIST_HEAD(&entry->list);
0152     kobject_init(&entry->kobj, &memmap_ktype);
0153
0154     spin_lock(&map_entries_lock);
0155     list_add_tail(&entry->list, &map_entries);
0156     spin_unlock(&map_entries_lock);
0157
0158     return 0;
0159 }
0160
0161 /**
0162  * firmware_map_remove_entry() - Does the real work to remove a firmware
0163  * memmap entry.
0164  * @entry: removed entry.
0165  *
0166  * The caller must hold map_entries_lock, and release it properly.
0167  */
0168 static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
0169 {
0170     list_del(&entry->list);
0171 }
0172
0173 /*
0174  * Add memmap entry on sysfs
0175  */
0176 static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry)
0177 {
0178     static int map_entries_nr;
0179     static struct kset *mmap_kset;
0180
0181     if (entry->kobj.state_in_sysfs)
0182         return -EEXIST;
0183
0184     if (!mmap_kset) {
0185         mmap_kset = kset_create_and_add("memmap", NULL, firmware_kobj);
0186         if (!mmap_kset)
0187             return -ENOMEM;
0188     }
0189
0190     entry->kobj.kset = mmap_kset;
0191     if (kobject_add(&entry->kobj, NULL, "%d", map_entries_nr++))
0192         kobject_put(&entry->kobj);
0193
0194     return 0;
0195 }
0196
0197 /*
0198  * Remove memmap entry on sysfs
0199  */
0200 static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
0201 {
0202     kobject_put(&entry->kobj);
0203 }
0204
0205 /**
0206  * firmware_map_find_entry_in_list() - Search memmap entry in a given list.
0207  * @start: Start of the memory range.
0208  * @end:   End of the memory range (exclusive).
0209  * @type:  Type of the memory range.
0210  * @list:  In which to find the entry.
0211  *
0212  * This function is to find the memmap entey of a given memory range in a
0213  * given list. The caller must hold map_entries_lock, and must not release
0214  * the lock until the processing of the returned entry has completed.
0215  *
0216  * Return: Pointer to the entry to be found on success, or NULL on failure.
0217  */
0218 static struct firmware_map_entry * __meminit
0219 firmware_map_find_entry_in_list(u64 start, u64 end, const char *type,
0220                 struct list_head *list)
0221 {
0222     struct firmware_map_entry *entry;
0223
0224     list_for_each_entry(entry, list, list)
0225         if ((entry->start == start) && (entry->end == end) &&
0226             (!strcmp(entry->type, type))) {
0227             return entry;
0228         }
0229
0230     return NULL;
0231 }
0232
0233 /**
0234  * firmware_map_find_entry() - Search memmap entry in map_entries.
0235  * @start: Start of the memory range.
0236  * @end:   End of the memory range (exclusive).
0237  * @type:  Type of the memory range.
0238  *
0239  * This function is to find the memmap entey of a given memory range.
0240  * The caller must hold map_entries_lock, and must not release the lock
0241  * until the processing of the returned entry has completed.
0242  *
0243  * Return: Pointer to the entry to be found on success, or NULL on failure.
0244  */
0245 static struct firmware_map_entry * __meminit
0246 firmware_map_find_entry(u64 start, u64 end, const char *type)
0247 {
0248     return firmware_map_find_entry_in_list(start, end, type, &map_entries);
0249 }
0250
0251 /**
0252  * firmware_map_find_entry_bootmem() - Search memmap entry in map_entries_bootmem.
0253  * @start: Start of the memory range.
0254  * @end:   End of the memory range (exclusive).
0255  * @type:  Type of the memory range.
0256  *
0257  * This function is similar to firmware_map_find_entry except that it find the
0258  * given entry in map_entries_bootmem.
0259  *
0260  * Return: Pointer to the entry to be found on success, or NULL on failure.
0261  */
0262 static struct firmware_map_entry * __meminit
0263 firmware_map_find_entry_bootmem(u64 start, u64 end, const char *type)
0264 {
0265     return firmware_map_find_entry_in_list(start, end, type,
0266                            &map_entries_bootmem);
0267 }
0268
0269 /**
0270  * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
0271  * memory hotplug.
0272  * @start: Start of the memory range.
0273  * @end:   End of the memory range (exclusive)
0274  * @type:  Type of the memory range.
0275  *
0276  * Adds a firmware mapping entry. This function is for memory hotplug, it is
0277  * similar to function firmware_map_add_early(). The only difference is that
0278  * it will create the syfs entry dynamically.
0279  *
0280  * Return: 0 on success, or -ENOMEM if no memory could be allocated.
0281  */
0282 int __meminit firmware_map_add_hotplug(u64 start, u64 end, const char *type)
0283 {
0284     struct firmware_map_entry *entry;
0285
0286     entry = firmware_map_find_entry(start, end - 1, type);
0287     if (entry)
0288         return 0;
0289
0290     entry = firmware_map_find_entry_bootmem(start, end - 1, type);
0291     if (!entry) {
0292         entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
0293         if (!entry)
0294             return -ENOMEM;
0295     } else {
0296         /* Reuse storage allocated by bootmem. */
0297         spin_lock(&map_entries_bootmem_lock);
0298         list_del(&entry->list);
0299         spin_unlock(&map_entries_bootmem_lock);
0300
0301         memset(entry, 0, sizeof(*entry));
0302     }
0303
0304     firmware_map_add_entry(start, end, type, entry);
0305     /* create the memmap entry */
0306     add_sysfs_fw_map_entry(entry);
0307
0308     return 0;
0309 }
0310
0311 /**
0312  * firmware_map_add_early() - Adds a firmware mapping entry.
0313  * @start: Start of the memory range.
0314  * @end:   End of the memory range.
0315  * @type:  Type of the memory range.
0316  *
0317  * Adds a firmware mapping entry. This function uses the bootmem allocator
0318  * for memory allocation.
0319  *
0320  * That function must be called before late_initcall.
0321  *
0322  * Return: 0 on success, or -ENOMEM if no memory could be allocated.
0323  */
0324 int __init firmware_map_add_early(u64 start, u64 end, const char *type)
0325 {
0326     struct firmware_map_entry *entry;
0327
0328     entry = memblock_alloc(sizeof(struct firmware_map_entry),
0329                    SMP_CACHE_BYTES);
0330     if (WARN_ON(!entry))
0331         return -ENOMEM;
0332
0333     return firmware_map_add_entry(start, end, type, entry);
0334 }
0335
0336 /**
0337  * firmware_map_remove() - remove a firmware mapping entry
0338  * @start: Start of the memory range.
0339  * @end:   End of the memory range.
0340  * @type:  Type of the memory range.
0341  *
0342  * removes a firmware mapping entry.
0343  *
0344  * Return: 0 on success, or -EINVAL if no entry.
0345  */
0346 int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
0347 {
0348     struct firmware_map_entry *entry;
0349
0350     spin_lock(&map_entries_lock);
0351     entry = firmware_map_find_entry(start, end - 1, type);
0352     if (!entry) {
0353         spin_unlock(&map_entries_lock);
0354         return -EINVAL;
0355     }
0356
0357     firmware_map_remove_entry(entry);
0358     spin_unlock(&map_entries_lock);
0359
0360     /* remove the memmap entry */
0361     remove_sysfs_fw_map_entry(entry);
0362
0363     return 0;
0364 }
0365
0366 /*
0367  * Sysfs functions -------------------------------------------------------------
0368  */
0369
0370 static ssize_t start_show(struct firmware_map_entry *entry, char *buf)
0371 {
0372     return snprintf(buf, PAGE_SIZE, "0x%llx\n",
0373         (unsigned long long)entry->start);
0374 }
0375
0376 static ssize_t end_show(struct firmware_map_entry *entry, char *buf)
0377 {
0378     return snprintf(buf, PAGE_SIZE, "0x%llx\n",
0379         (unsigned long long)entry->end);
0380 }
0381
0382 static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
0383 {
0384     return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
0385 }
0386
0387 static inline struct memmap_attribute *to_memmap_attr(struct attribute *attr)
0388 {
0389     return container_of(attr, struct memmap_attribute, attr);
0390 }
0391
0392 static ssize_t memmap_attr_show(struct kobject *kobj,
0393                 struct attribute *attr, char *buf)
0394 {
0395     struct firmware_map_entry *entry = to_memmap_entry(kobj);
0396     struct memmap_attribute *memmap_attr = to_memmap_attr(attr);
0397
0398     return memmap_attr->show(entry, buf);
0399 }
0400
0401 /*
0402  * Initialises stuff and adds the entries in the map_entries list to
0403  * sysfs. Important is that firmware_map_add() and firmware_map_add_early()
0404  * must be called before late_initcall. That's just because that function
0405  * is called as late_initcall() function, which means that if you call
0406  * firmware_map_add() or firmware_map_add_early() afterwards, the entries
0407  * are not added to sysfs.
0408  */
0409 static int __init firmware_memmap_init(void)
0410 {
0411     struct firmware_map_entry *entry;
0412
0413     list_for_each_entry(entry, &map_entries, list)
0414         add_sysfs_fw_map_entry(entry);
0415
0416     return 0;
0417 }
0418 late_initcall(firmware_memmap_init);
0419