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/cacheflush.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
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 int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)
49 {
50 struct memtrace_entry *ent = filp->private_data;
51
52 if (ent->size < vma->vm_end - vma->vm_start)
53 return -EINVAL;
54
55 if (vma->vm_pgoff << PAGE_SHIFT >= ent->size)
56 return -EINVAL;
57
58 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
59 return remap_pfn_range(vma, vma->vm_start, PHYS_PFN(ent->start) + vma->vm_pgoff,
60 vma->vm_end - vma->vm_start, vma->vm_page_prot);
61 }
62
63 static const struct file_operations memtrace_fops = {
64 .llseek = default_llseek,
65 .read = memtrace_read,
66 .open = simple_open,
67 .mmap = memtrace_mmap,
68 };
69
70 #define FLUSH_CHUNK_SIZE SZ_1G
71 /**
72 * flush_dcache_range_chunked(): Write any modified data cache blocks out to
73 * memory and invalidate them, in chunks of up to FLUSH_CHUNK_SIZE
74 * Does not invalidate the corresponding instruction cache blocks.
75 *
76 * @start: the start address
77 * @stop: the stop address (exclusive)
78 * @chunk: the max size of the chunks
79 */
80 static void flush_dcache_range_chunked(unsigned long start, unsigned long stop,
81 unsigned long chunk)
82 {
83 unsigned long i;
84
85 for (i = start; i < stop; i += chunk) {
86 flush_dcache_range(i, min(stop, i + chunk));
87 cond_resched();
88 }
89 }
90
91 static void memtrace_clear_range(unsigned long start_pfn,
92 unsigned long nr_pages)
93 {
94 unsigned long pfn;
95
96 /* As HIGHMEM does not apply, use clear_page() directly. */
97 for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) {
98 if (IS_ALIGNED(pfn, PAGES_PER_SECTION))
99 cond_resched();
100 clear_page(__va(PFN_PHYS(pfn)));
101 }
102 /*
103 * Before we go ahead and use this range as cache inhibited range
104 * flush the cache.
105 */
106 flush_dcache_range_chunked((unsigned long)pfn_to_kaddr(start_pfn),
107 (unsigned long)pfn_to_kaddr(start_pfn + nr_pages),
108 FLUSH_CHUNK_SIZE);
109 }
110
111 static u64 memtrace_alloc_node(u32 nid, u64 size)
112 {
113 const unsigned long nr_pages = PHYS_PFN(size);
114 unsigned long pfn, start_pfn;
115 struct page *page;
116
117 /*
118 * Trace memory needs to be aligned to the size, which is guaranteed
119 * by alloc_contig_pages().
120 */
121 page = alloc_contig_pages(nr_pages, GFP_KERNEL | __GFP_THISNODE |
122 __GFP_NOWARN, nid, NULL);
123 if (!page)
124 return 0;
125 start_pfn = page_to_pfn(page);
126
127 /*
128 * Clear the range while we still have a linear mapping.
129 *
130 * TODO: use __GFP_ZERO with alloc_contig_pages() once supported.
131 */
132 memtrace_clear_range(start_pfn, nr_pages);
133
134 /*
135 * Set pages PageOffline(), to indicate that nobody (e.g., hibernation,
136 * dumping, ...) should be touching these pages.
137 */
138 for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
139 __SetPageOffline(pfn_to_page(pfn));
140
141 arch_remove_linear_mapping(PFN_PHYS(start_pfn), size);
142
143 return PFN_PHYS(start_pfn);
144 }
145
146 static int memtrace_init_regions_runtime(u64 size)
147 {
148 u32 nid;
149 u64 m;
150
151 memtrace_array = kcalloc(num_online_nodes(),
152 sizeof(struct memtrace_entry), GFP_KERNEL);
153 if (!memtrace_array) {
154 pr_err("Failed to allocate memtrace_array\n");
155 return -EINVAL;
156 }
157
158 for_each_online_node(nid) {
159 m = memtrace_alloc_node(nid, size);
160
161 /*
162 * A node might not have any local memory, so warn but
163 * continue on.
164 */
165 if (!m) {
166 pr_err("Failed to allocate trace memory on node %d\n", nid);
167 continue;
168 }
169
170 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
171
172 memtrace_array[memtrace_array_nr].start = m;
173 memtrace_array[memtrace_array_nr].size = size;
174 memtrace_array[memtrace_array_nr].nid = nid;
175 memtrace_array_nr++;
176 }
177
178 return 0;
179 }
180
181 static struct dentry *memtrace_debugfs_dir;
182
183 static int memtrace_init_debugfs(void)
184 {
185 int ret = 0;
186 int i;
187
188 for (i = 0; i < memtrace_array_nr; i++) {
189 struct dentry *dir;
190 struct memtrace_entry *ent = &memtrace_array[i];
191
192 ent->mem = ioremap(ent->start, ent->size);
193 /* Warn but continue on */
194 if (!ent->mem) {
195 pr_err("Failed to map trace memory at 0x%llx\n",
196 ent->start);
197 ret = -1;
198 continue;
199 }
200
201 snprintf(ent->name, 16, "%08x", ent->nid);
202 dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
203
204 ent->dir = dir;
205 debugfs_create_file_unsafe("trace", 0600, dir, ent, &memtrace_fops);
206 debugfs_create_x64("start", 0400, dir, &ent->start);
207 debugfs_create_x64("size", 0400, dir, &ent->size);
208 }
209
210 return ret;
211 }
212
213 static int memtrace_free(int nid, u64 start, u64 size)
214 {
215 struct mhp_params params = { .pgprot = PAGE_KERNEL };
216 const unsigned long nr_pages = PHYS_PFN(size);
217 const unsigned long start_pfn = PHYS_PFN(start);
218 unsigned long pfn;
219 int ret;
220
221 ret = arch_create_linear_mapping(nid, start, size, ¶ms);
222 if (ret)
223 return ret;
224
225 for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
226 __ClearPageOffline(pfn_to_page(pfn));
227
228 free_contig_range(start_pfn, nr_pages);
229 return 0;
230 }
231
232 /*
233 * Iterate through the chunks of memory we allocated and attempt to expose
234 * them back to the kernel.
235 */
236 static int memtrace_free_regions(void)
237 {
238 int i, ret = 0;
239 struct memtrace_entry *ent;
240
241 for (i = memtrace_array_nr - 1; i >= 0; i--) {
242 ent = &memtrace_array[i];
243
244 /* We have freed this chunk previously */
245 if (ent->nid == NUMA_NO_NODE)
246 continue;
247
248 /* Remove from io mappings */
249 if (ent->mem) {
250 iounmap(ent->mem);
251 ent->mem = 0;
252 }
253
254 if (memtrace_free(ent->nid, ent->start, ent->size)) {
255 pr_err("Failed to free trace memory on node %d\n",
256 ent->nid);
257 ret += 1;
258 continue;
259 }
260
261 /*
262 * Memory was freed successfully so clean up references to it
263 * so on reentry we can tell that this chunk was freed.
264 */
265 debugfs_remove_recursive(ent->dir);
266 pr_info("Freed trace memory back on node %d\n", ent->nid);
267 ent->size = ent->start = ent->nid = NUMA_NO_NODE;
268 }
269 if (ret)
270 return ret;
271
272 /* If all chunks of memory were freed successfully, reset globals */
273 kfree(memtrace_array);
274 memtrace_array = NULL;
275 memtrace_size = 0;
276 memtrace_array_nr = 0;
277 return 0;
278 }
279
280 static int memtrace_enable_set(void *data, u64 val)
281 {
282 int rc = -EAGAIN;
283 u64 bytes;
284
285 /*
286 * Don't attempt to do anything if size isn't aligned to a memory
287 * block or equal to zero.
288 */
289 bytes = memory_block_size_bytes();
290 if (val & (bytes - 1)) {
291 pr_err("Value must be aligned with 0x%llx\n", bytes);
292 return -EINVAL;
293 }
294
295 mutex_lock(&memtrace_mutex);
296
297 /* Free all previously allocated memory. */
298 if (memtrace_size && memtrace_free_regions())
299 goto out_unlock;
300
301 if (!val) {
302 rc = 0;
303 goto out_unlock;
304 }
305
306 /* Allocate memory. */
307 if (memtrace_init_regions_runtime(val))
308 goto out_unlock;
309
310 if (memtrace_init_debugfs())
311 goto out_unlock;
312
313 memtrace_size = val;
314 rc = 0;
315 out_unlock:
316 mutex_unlock(&memtrace_mutex);
317 return rc;
318 }
319
320 static int memtrace_enable_get(void *data, u64 *val)
321 {
322 *val = memtrace_size;
323 return 0;
324 }
325
326 DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
327 memtrace_enable_set, "0x%016llx\n");
328
329 static int memtrace_init(void)
330 {
331 memtrace_debugfs_dir = debugfs_create_dir("memtrace",
332 arch_debugfs_dir);
333
334 debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
335 NULL, &memtrace_init_fops);
336
337 return 0;
338 }
339 machine_device_initcall(powernv, memtrace_init);
340
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