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