1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) IBM Corporation, 2014, 2017
4 * Anton Blanchard, Rashmica Gupta.
5 */
6
7 #define pr_fmt(fmt) "memtrace: " fmt
8
9 #include <linux/bitops.h>
10 #include <linux/string.h>
11 #include <linux/memblock.h>
12 #include <linux/init.h>
13 #include <linux/moduleparam.h>
14 #include <linux/fs.h>
15 #include <linux/debugfs.h>
16 #include <linux/slab.h>
17 #include <linux/memory.h>
18 #include <linux/memory_hotplug.h>
19 #include <linux/numa.h>
20 #include <asm/machdep.h>
21 #include <asm/debugfs.h>
22
23 /* This enables us to keep track of the memory removed from each node. */
24 struct memtrace_entry {
25 void *mem;
26 u64 start;
27 u64 size;
28 u32 nid;
29 struct dentry *dir;
30 char name[16];
31 };
32
33 static DEFINE_MUTEX(memtrace_mutex);
34 static u64 memtrace_size;
35
36 static struct memtrace_entry *memtrace_array;
37 static unsigned int memtrace_array_nr;
38
39
memtrace_read(struct file * filp,char __user * ubuf,size_t count,loff_t * ppos)40 static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
41 size_t count, loff_t *ppos)
42 {
43 struct memtrace_entry *ent = filp->private_data;
44
45 return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);
46 }
47
48 static const struct file_operations memtrace_fops = {
49 .llseek = default_llseek,
50 .read = memtrace_read,
51 .open = simple_open,
52 };
53
check_memblock_online(struct memory_block * mem,void * arg)54 static int check_memblock_online(struct memory_block *mem, void *arg)
55 {
56 if (mem->state != MEM_ONLINE)
57 return -1;
58
59 return 0;
60 }
61
change_memblock_state(struct memory_block * mem,void * arg)62 static int change_memblock_state(struct memory_block *mem, void *arg)
63 {
64 unsigned long state = (unsigned long)arg;
65
66 mem->state = state;
67
68 return 0;
69 }
70
memtrace_clear_range(unsigned long start_pfn,unsigned long nr_pages)71 static void memtrace_clear_range(unsigned long start_pfn,
72 unsigned long nr_pages)
73 {
74 unsigned long pfn;
75
76 /*
77 * As pages are offline, we cannot trust the memmap anymore. As HIGHMEM
78 * does not apply, avoid passing around "struct page" and use
79 * clear_page() instead directly.
80 */
81 for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) {
82 if (IS_ALIGNED(pfn, PAGES_PER_SECTION))
83 cond_resched();
84 clear_page(__va(PFN_PHYS(pfn)));
85 }
86 }
87
88 /* called with device_hotplug_lock held */
memtrace_offline_pages(u32 nid,u64 start_pfn,u64 nr_pages)89 static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
90 {
91 const unsigned long start = PFN_PHYS(start_pfn);
92 const unsigned long size = PFN_PHYS(nr_pages);
93
94 if (walk_memory_blocks(start, size, NULL, check_memblock_online))
95 return false;
96
97 walk_memory_blocks(start, size, (void *)MEM_GOING_OFFLINE,
98 change_memblock_state);
99
100 if (offline_pages(start_pfn, nr_pages)) {
101 walk_memory_blocks(start, size, (void *)MEM_ONLINE,
102 change_memblock_state);
103 return false;
104 }
105
106 walk_memory_blocks(start, size, (void *)MEM_OFFLINE,
107 change_memblock_state);
108
109
110 return true;
111 }
112
memtrace_alloc_node(u32 nid,u64 size)113 static u64 memtrace_alloc_node(u32 nid, u64 size)
114 {
115 u64 start_pfn, end_pfn, nr_pages, pfn;
116 u64 base_pfn;
117 u64 bytes = memory_block_size_bytes();
118
119 if (!node_spanned_pages(nid))
120 return 0;
121
122 start_pfn = node_start_pfn(nid);
123 end_pfn = node_end_pfn(nid);
124 nr_pages = size >> PAGE_SHIFT;
125
126 /* Trace memory needs to be aligned to the size */
127 end_pfn = round_down(end_pfn - nr_pages, nr_pages);
128
129 lock_device_hotplug();
130 for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) {
131 if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) {
132 /*
133 * Clear the range while we still have a linear
134 * mapping.
135 */
136 memtrace_clear_range(base_pfn, nr_pages);
137 /*
138 * Remove memory in memory block size chunks so that
139 * iomem resources are always split to the same size and
140 * we never try to remove memory that spans two iomem
141 * resources.
142 */
143 end_pfn = base_pfn + nr_pages;
144 for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) {
145 __remove_memory(nid, pfn << PAGE_SHIFT, bytes);
146 }
147 unlock_device_hotplug();
148 return base_pfn << PAGE_SHIFT;
149 }
150 }
151 unlock_device_hotplug();
152
153 return 0;
154 }
155
memtrace_init_regions_runtime(u64 size)156 static int memtrace_init_regions_runtime(u64 size)
157 {
158 u32 nid;
159 u64 m;
160
161 memtrace_array = kcalloc(num_online_nodes(),
162 sizeof(struct memtrace_entry), GFP_KERNEL);
163 if (!memtrace_array) {
164 pr_err("Failed to allocate memtrace_array\n");
165 return -EINVAL;
166 }
167
168 for_each_online_node(nid) {
169 m = memtrace_alloc_node(nid, size);
170
171 /*
172 * A node might not have any local memory, so warn but
173 * continue on.
174 */
175 if (!m) {
176 pr_err("Failed to allocate trace memory on node %d\n", nid);
177 continue;
178 }
179
180 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
181
182 memtrace_array[memtrace_array_nr].start = m;
183 memtrace_array[memtrace_array_nr].size = size;
184 memtrace_array[memtrace_array_nr].nid = nid;
185 memtrace_array_nr++;
186 }
187
188 return 0;
189 }
190
191 static struct dentry *memtrace_debugfs_dir;
192
memtrace_init_debugfs(void)193 static int memtrace_init_debugfs(void)
194 {
195 int ret = 0;
196 int i;
197
198 for (i = 0; i < memtrace_array_nr; i++) {
199 struct dentry *dir;
200 struct memtrace_entry *ent = &memtrace_array[i];
201
202 ent->mem = ioremap(ent->start, ent->size);
203 /* Warn but continue on */
204 if (!ent->mem) {
205 pr_err("Failed to map trace memory at 0x%llx\n",
206 ent->start);
207 ret = -1;
208 continue;
209 }
210
211 snprintf(ent->name, 16, "%08x", ent->nid);
212 dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
213
214 ent->dir = dir;
215 debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
216 debugfs_create_x64("start", 0400, dir, &ent->start);
217 debugfs_create_x64("size", 0400, dir, &ent->size);
218 }
219
220 return ret;
221 }
222
online_mem_block(struct memory_block * mem,void * arg)223 static int online_mem_block(struct memory_block *mem, void *arg)
224 {
225 return device_online(&mem->dev);
226 }
227
228 /*
229 * Iterate through the chunks of memory we have removed from the kernel
230 * and attempt to add them back to the kernel.
231 */
memtrace_online(void)232 static int memtrace_online(void)
233 {
234 int i, ret = 0;
235 struct memtrace_entry *ent;
236
237 for (i = memtrace_array_nr - 1; i >= 0; i--) {
238 ent = &memtrace_array[i];
239
240 /* We have onlined this chunk previously */
241 if (ent->nid == NUMA_NO_NODE)
242 continue;
243
244 /* Remove from io mappings */
245 if (ent->mem) {
246 iounmap(ent->mem);
247 ent->mem = 0;
248 }
249
250 if (add_memory(ent->nid, ent->start, ent->size, MHP_NONE)) {
251 pr_err("Failed to add trace memory to node %d\n",
252 ent->nid);
253 ret += 1;
254 continue;
255 }
256
257 lock_device_hotplug();
258 walk_memory_blocks(ent->start, ent->size, NULL,
259 online_mem_block);
260 unlock_device_hotplug();
261
262 /*
263 * Memory was added successfully so clean up references to it
264 * so on reentry we can tell that this chunk was added.
265 */
266 debugfs_remove_recursive(ent->dir);
267 pr_info("Added trace memory back to node %d\n", ent->nid);
268 ent->size = ent->start = ent->nid = NUMA_NO_NODE;
269 }
270 if (ret)
271 return ret;
272
273 /* If all chunks of memory were added successfully, reset globals */
274 kfree(memtrace_array);
275 memtrace_array = NULL;
276 memtrace_size = 0;
277 memtrace_array_nr = 0;
278 return 0;
279 }
280
memtrace_enable_set(void * data,u64 val)281 static int memtrace_enable_set(void *data, u64 val)
282 {
283 int rc = -EAGAIN;
284 u64 bytes;
285
286 /*
287 * Don't attempt to do anything if size isn't aligned to a memory
288 * block or equal to zero.
289 */
290 bytes = memory_block_size_bytes();
291 if (val & (bytes - 1)) {
292 pr_err("Value must be aligned with 0x%llx\n", bytes);
293 return -EINVAL;
294 }
295
296 mutex_lock(&memtrace_mutex);
297
298 /* Re-add/online previously removed/offlined memory */
299 if (memtrace_size) {
300 if (memtrace_online())
301 goto out_unlock;
302 }
303
304 if (!val) {
305 rc = 0;
306 goto out_unlock;
307 }
308
309 /* Offline and remove memory */
310 if (memtrace_init_regions_runtime(val))
311 goto out_unlock;
312
313 if (memtrace_init_debugfs())
314 goto out_unlock;
315
316 memtrace_size = val;
317 rc = 0;
318 out_unlock:
319 mutex_unlock(&memtrace_mutex);
320 return rc;
321 }
322
memtrace_enable_get(void * data,u64 * val)323 static int memtrace_enable_get(void *data, u64 *val)
324 {
325 *val = memtrace_size;
326 return 0;
327 }
328
329 DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
330 memtrace_enable_set, "0x%016llx\n");
331
memtrace_init(void)332 static int memtrace_init(void)
333 {
334 memtrace_debugfs_dir = debugfs_create_dir("memtrace",
335 powerpc_debugfs_root);
336
337 debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
338 NULL, &memtrace_init_fops);
339
340 return 0;
341 }
342 machine_device_initcall(powernv, memtrace_init);
343