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 ATTRIBUTE_GROUPS(def);
73 
74 static const struct sysfs_ops memmap_attr_ops = {
75 	.show = memmap_attr_show,
76 };
77 
78 /* Firmware memory map entries. */
79 static LIST_HEAD(map_entries);
80 static DEFINE_SPINLOCK(map_entries_lock);
81 
82 /*
83  * For memory hotplug, there is no way to free memory map entries allocated
84  * by boot mem after the system is up. So when we hot-remove memory whose
85  * map entry is allocated by bootmem, we need to remember the storage and
86  * reuse it when the memory is hot-added again.
87  */
88 static LIST_HEAD(map_entries_bootmem);
89 static DEFINE_SPINLOCK(map_entries_bootmem_lock);
90 
91 
92 static inline struct firmware_map_entry *
to_memmap_entry(struct kobject * kobj)93 to_memmap_entry(struct kobject *kobj)
94 {
95 	return container_of(kobj, struct firmware_map_entry, kobj);
96 }
97 
release_firmware_map_entry(struct kobject * kobj)98 static void __meminit release_firmware_map_entry(struct kobject *kobj)
99 {
100 	struct firmware_map_entry *entry = to_memmap_entry(kobj);
101 
102 	if (PageReserved(virt_to_page(entry))) {
103 		/*
104 		 * Remember the storage allocated by bootmem, and reuse it when
105 		 * the memory is hot-added again. The entry will be added to
106 		 * map_entries_bootmem here, and deleted from &map_entries in
107 		 * firmware_map_remove_entry().
108 		 */
109 		spin_lock(&map_entries_bootmem_lock);
110 		list_add(&entry->list, &map_entries_bootmem);
111 		spin_unlock(&map_entries_bootmem_lock);
112 
113 		return;
114 	}
115 
116 	kfree(entry);
117 }
118 
119 static struct kobj_type __refdata memmap_ktype = {
120 	.release	= release_firmware_map_entry,
121 	.sysfs_ops	= &memmap_attr_ops,
122 	.default_groups	= def_groups,
123 };
124 
125 /*
126  * Registration functions ------------------------------------------------------
127  */
128 
129 /**
130  * firmware_map_add_entry() - Does the real work to add a firmware memmap entry.
131  * @start: Start of the memory range.
132  * @end:   End of the memory range (exclusive).
133  * @type:  Type of the memory range.
134  * @entry: Pre-allocated (either kmalloc() or bootmem allocator), uninitialised
135  *         entry.
136  *
137  * Common implementation of firmware_map_add() and firmware_map_add_early()
138  * which expects a pre-allocated struct firmware_map_entry.
139  *
140  * Return: 0 always
141  */
firmware_map_add_entry(u64 start,u64 end,const char * type,struct firmware_map_entry * entry)142 static int firmware_map_add_entry(u64 start, u64 end,
143 				  const char *type,
144 				  struct firmware_map_entry *entry)
145 {
146 	BUG_ON(start > end);
147 
148 	entry->start = start;
149 	entry->end = end - 1;
150 	entry->type = type;
151 	INIT_LIST_HEAD(&entry->list);
152 	kobject_init(&entry->kobj, &memmap_ktype);
153 
154 	spin_lock(&map_entries_lock);
155 	list_add_tail(&entry->list, &map_entries);
156 	spin_unlock(&map_entries_lock);
157 
158 	return 0;
159 }
160 
161 /**
162  * firmware_map_remove_entry() - Does the real work to remove a firmware
163  * memmap entry.
164  * @entry: removed entry.
165  *
166  * The caller must hold map_entries_lock, and release it properly.
167  */
firmware_map_remove_entry(struct firmware_map_entry * entry)168 static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
169 {
170 	list_del(&entry->list);
171 }
172 
173 /*
174  * Add memmap entry on sysfs
175  */
add_sysfs_fw_map_entry(struct firmware_map_entry * entry)176 static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry)
177 {
178 	static int map_entries_nr;
179 	static struct kset *mmap_kset;
180 
181 	if (entry->kobj.state_in_sysfs)
182 		return -EEXIST;
183 
184 	if (!mmap_kset) {
185 		mmap_kset = kset_create_and_add("memmap", NULL, firmware_kobj);
186 		if (!mmap_kset)
187 			return -ENOMEM;
188 	}
189 
190 	entry->kobj.kset = mmap_kset;
191 	if (kobject_add(&entry->kobj, NULL, "%d", map_entries_nr++))
192 		kobject_put(&entry->kobj);
193 
194 	return 0;
195 }
196 
197 /*
198  * Remove memmap entry on sysfs
199  */
remove_sysfs_fw_map_entry(struct firmware_map_entry * entry)200 static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
201 {
202 	kobject_put(&entry->kobj);
203 }
204 
205 /**
206  * firmware_map_find_entry_in_list() - Search memmap entry in a given list.
207  * @start: Start of the memory range.
208  * @end:   End of the memory range (exclusive).
209  * @type:  Type of the memory range.
210  * @list:  In which to find the entry.
211  *
212  * This function is to find the memmap entey of a given memory range in a
213  * given list. The caller must hold map_entries_lock, and must not release
214  * the lock until the processing of the returned entry has completed.
215  *
216  * Return: Pointer to the entry to be found on success, or NULL on failure.
217  */
218 static struct firmware_map_entry * __meminit
firmware_map_find_entry_in_list(u64 start,u64 end,const char * type,struct list_head * list)219 firmware_map_find_entry_in_list(u64 start, u64 end, const char *type,
220 				struct list_head *list)
221 {
222 	struct firmware_map_entry *entry;
223 
224 	list_for_each_entry(entry, list, list)
225 		if ((entry->start == start) && (entry->end == end) &&
226 		    (!strcmp(entry->type, type))) {
227 			return entry;
228 		}
229 
230 	return NULL;
231 }
232 
233 /**
234  * firmware_map_find_entry() - Search memmap entry in map_entries.
235  * @start: Start of the memory range.
236  * @end:   End of the memory range (exclusive).
237  * @type:  Type of the memory range.
238  *
239  * This function is to find the memmap entey of a given memory range.
240  * The caller must hold map_entries_lock, and must not release the lock
241  * until the processing of the returned entry has completed.
242  *
243  * Return: Pointer to the entry to be found on success, or NULL on failure.
244  */
245 static struct firmware_map_entry * __meminit
firmware_map_find_entry(u64 start,u64 end,const char * type)246 firmware_map_find_entry(u64 start, u64 end, const char *type)
247 {
248 	return firmware_map_find_entry_in_list(start, end, type, &map_entries);
249 }
250 
251 /**
252  * firmware_map_find_entry_bootmem() - Search memmap entry in map_entries_bootmem.
253  * @start: Start of the memory range.
254  * @end:   End of the memory range (exclusive).
255  * @type:  Type of the memory range.
256  *
257  * This function is similar to firmware_map_find_entry except that it find the
258  * given entry in map_entries_bootmem.
259  *
260  * Return: Pointer to the entry to be found on success, or NULL on failure.
261  */
262 static struct firmware_map_entry * __meminit
firmware_map_find_entry_bootmem(u64 start,u64 end,const char * type)263 firmware_map_find_entry_bootmem(u64 start, u64 end, const char *type)
264 {
265 	return firmware_map_find_entry_in_list(start, end, type,
266 					       &map_entries_bootmem);
267 }
268 
269 /**
270  * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
271  * memory hotplug.
272  * @start: Start of the memory range.
273  * @end:   End of the memory range (exclusive)
274  * @type:  Type of the memory range.
275  *
276  * Adds a firmware mapping entry. This function is for memory hotplug, it is
277  * similar to function firmware_map_add_early(). The only difference is that
278  * it will create the syfs entry dynamically.
279  *
280  * Return: 0 on success, or -ENOMEM if no memory could be allocated.
281  */
firmware_map_add_hotplug(u64 start,u64 end,const char * type)282 int __meminit firmware_map_add_hotplug(u64 start, u64 end, const char *type)
283 {
284 	struct firmware_map_entry *entry;
285 
286 	entry = firmware_map_find_entry(start, end - 1, type);
287 	if (entry)
288 		return 0;
289 
290 	entry = firmware_map_find_entry_bootmem(start, end - 1, type);
291 	if (!entry) {
292 		entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
293 		if (!entry)
294 			return -ENOMEM;
295 	} else {
296 		/* Reuse storage allocated by bootmem. */
297 		spin_lock(&map_entries_bootmem_lock);
298 		list_del(&entry->list);
299 		spin_unlock(&map_entries_bootmem_lock);
300 
301 		memset(entry, 0, sizeof(*entry));
302 	}
303 
304 	firmware_map_add_entry(start, end, type, entry);
305 	/* create the memmap entry */
306 	add_sysfs_fw_map_entry(entry);
307 
308 	return 0;
309 }
310 
311 /**
312  * firmware_map_add_early() - Adds a firmware mapping entry.
313  * @start: Start of the memory range.
314  * @end:   End of the memory range.
315  * @type:  Type of the memory range.
316  *
317  * Adds a firmware mapping entry. This function uses the bootmem allocator
318  * for memory allocation.
319  *
320  * That function must be called before late_initcall.
321  *
322  * Return: 0 on success, or -ENOMEM if no memory could be allocated.
323  */
firmware_map_add_early(u64 start,u64 end,const char * type)324 int __init firmware_map_add_early(u64 start, u64 end, const char *type)
325 {
326 	struct firmware_map_entry *entry;
327 
328 	entry = memblock_alloc(sizeof(struct firmware_map_entry),
329 			       SMP_CACHE_BYTES);
330 	if (WARN_ON(!entry))
331 		return -ENOMEM;
332 
333 	return firmware_map_add_entry(start, end, type, entry);
334 }
335 
336 /**
337  * firmware_map_remove() - remove a firmware mapping entry
338  * @start: Start of the memory range.
339  * @end:   End of the memory range.
340  * @type:  Type of the memory range.
341  *
342  * removes a firmware mapping entry.
343  *
344  * Return: 0 on success, or -EINVAL if no entry.
345  */
firmware_map_remove(u64 start,u64 end,const char * type)346 int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
347 {
348 	struct firmware_map_entry *entry;
349 
350 	spin_lock(&map_entries_lock);
351 	entry = firmware_map_find_entry(start, end - 1, type);
352 	if (!entry) {
353 		spin_unlock(&map_entries_lock);
354 		return -EINVAL;
355 	}
356 
357 	firmware_map_remove_entry(entry);
358 	spin_unlock(&map_entries_lock);
359 
360 	/* remove the memmap entry */
361 	remove_sysfs_fw_map_entry(entry);
362 
363 	return 0;
364 }
365 
366 /*
367  * Sysfs functions -------------------------------------------------------------
368  */
369 
start_show(struct firmware_map_entry * entry,char * buf)370 static ssize_t start_show(struct firmware_map_entry *entry, char *buf)
371 {
372 	return snprintf(buf, PAGE_SIZE, "0x%llx\n",
373 		(unsigned long long)entry->start);
374 }
375 
end_show(struct firmware_map_entry * entry,char * buf)376 static ssize_t end_show(struct firmware_map_entry *entry, char *buf)
377 {
378 	return snprintf(buf, PAGE_SIZE, "0x%llx\n",
379 		(unsigned long long)entry->end);
380 }
381 
type_show(struct firmware_map_entry * entry,char * buf)382 static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
383 {
384 	return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
385 }
386 
to_memmap_attr(struct attribute * attr)387 static inline struct memmap_attribute *to_memmap_attr(struct attribute *attr)
388 {
389 	return container_of(attr, struct memmap_attribute, attr);
390 }
391 
memmap_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)392 static ssize_t memmap_attr_show(struct kobject *kobj,
393 				struct attribute *attr, char *buf)
394 {
395 	struct firmware_map_entry *entry = to_memmap_entry(kobj);
396 	struct memmap_attribute *memmap_attr = to_memmap_attr(attr);
397 
398 	return memmap_attr->show(entry, buf);
399 }
400 
401 /*
402  * Initialises stuff and adds the entries in the map_entries list to
403  * sysfs. Important is that firmware_map_add() and firmware_map_add_early()
404  * must be called before late_initcall. That's just because that function
405  * is called as late_initcall() function, which means that if you call
406  * firmware_map_add() or firmware_map_add_early() afterwards, the entries
407  * are not added to sysfs.
408  */
firmware_memmap_init(void)409 static int __init firmware_memmap_init(void)
410 {
411 	struct firmware_map_entry *entry;
412 
413 	list_for_each_entry(entry, &map_entries, list)
414 		add_sysfs_fw_map_entry(entry);
415 
416 	return 0;
417 }
418 late_initcall(firmware_memmap_init);
419 
420