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. */
24struct memtrace_entry {
25 void *mem;
26 u64 start;
27 u64 size;
28 u32 nid;
29 struct dentry *dir;
30 char name[16];
31};
32
33static DEFINE_MUTEX(memtrace_mutex);
34static u64 memtrace_size;
35
36static struct memtrace_entry *memtrace_array;
37static unsigned int memtrace_array_nr;
38
39
40static 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(to: ubuf, count, ppos, from: ent->mem, available: ent->size);
46}
47
48static int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)
49{
50 struct memtrace_entry *ent = filp->private_data;
51 unsigned long ent_nrpages = ent->size >> PAGE_SHIFT;
52 unsigned long vma_nrpages = vma_pages(vma);
53
54 /* The requested page offset should be within object's page count */
55 if (vma->vm_pgoff >= ent_nrpages)
56 return -EINVAL;
57
58 /* The requested mapping range should remain within the bounds */
59 if (vma_nrpages > ent_nrpages - vma->vm_pgoff)
60 return -EINVAL;
61
62 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
63 return remap_pfn_range(vma, addr: vma->vm_start, PHYS_PFN(ent->start) + vma->vm_pgoff,
64 size: vma->vm_end - vma->vm_start, pgprot: vma->vm_page_prot);
65}
66
67static const struct file_operations memtrace_fops = {
68 .llseek = default_llseek,
69 .read = memtrace_read,
70 .open = simple_open,
71 .mmap = memtrace_mmap,
72};
73
74#define FLUSH_CHUNK_SIZE SZ_1G
75/**
76 * flush_dcache_range_chunked(): Write any modified data cache blocks out to
77 * memory and invalidate them, in chunks of up to FLUSH_CHUNK_SIZE
78 * Does not invalidate the corresponding instruction cache blocks.
79 *
80 * @start: the start address
81 * @stop: the stop address (exclusive)
82 * @chunk: the max size of the chunks
83 */
84static void flush_dcache_range_chunked(unsigned long start, unsigned long stop,
85 unsigned long chunk)
86{
87 unsigned long i;
88
89 for (i = start; i < stop; i += chunk) {
90 flush_dcache_range(i, min(stop, i + chunk));
91 cond_resched();
92 }
93}
94
95static u64 memtrace_alloc_node(u32 nid, u64 size)
96{
97 const unsigned long nr_pages = PHYS_PFN(size);
98 unsigned long pfn, start_pfn;
99 struct page *page;
100
101 /*
102 * Trace memory needs to be aligned to the size, which is guaranteed
103 * by alloc_contig_pages().
104 */
105 page = alloc_contig_pages(nr_pages, GFP_KERNEL | __GFP_THISNODE |
106 __GFP_NOWARN | __GFP_ZERO, nid, NULL);
107 if (!page)
108 return 0;
109 start_pfn = page_to_pfn(page);
110
111 /*
112 * Before we go ahead and use this range as cache inhibited range
113 * flush the cache.
114 */
115 flush_dcache_range_chunked(start: (unsigned long)pfn_to_kaddr(pfn: start_pfn),
116 stop: (unsigned long)pfn_to_kaddr(pfn: start_pfn + nr_pages),
117 FLUSH_CHUNK_SIZE);
118
119 /*
120 * Set pages PageOffline(), to indicate that nobody (e.g., hibernation,
121 * dumping, ...) should be touching these pages.
122 */
123 for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
124 __SetPageOffline(pfn_to_page(pfn));
125
126 arch_remove_linear_mapping(PFN_PHYS(start_pfn), size);
127
128 return PFN_PHYS(start_pfn);
129}
130
131static int memtrace_init_regions_runtime(u64 size)
132{
133 u32 nid;
134 u64 m;
135
136 memtrace_array = kcalloc(num_online_nodes(),
137 sizeof(struct memtrace_entry), GFP_KERNEL);
138 if (!memtrace_array) {
139 pr_err("Failed to allocate memtrace_array\n");
140 return -EINVAL;
141 }
142
143 for_each_online_node(nid) {
144 m = memtrace_alloc_node(nid, size);
145
146 /*
147 * A node might not have any local memory, so warn but
148 * continue on.
149 */
150 if (!m) {
151 pr_err("Failed to allocate trace memory on node %d\n", nid);
152 continue;
153 }
154
155 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
156
157 memtrace_array[memtrace_array_nr].start = m;
158 memtrace_array[memtrace_array_nr].size = size;
159 memtrace_array[memtrace_array_nr].nid = nid;
160 memtrace_array_nr++;
161 }
162
163 return 0;
164}
165
166static struct dentry *memtrace_debugfs_dir;
167
168static int memtrace_init_debugfs(void)
169{
170 int ret = 0;
171 int i;
172
173 for (i = 0; i < memtrace_array_nr; i++) {
174 struct dentry *dir;
175 struct memtrace_entry *ent = &memtrace_array[i];
176
177 ent->mem = ioremap(offset: ent->start, size: ent->size);
178 /* Warn but continue on */
179 if (!ent->mem) {
180 pr_err("Failed to map trace memory at 0x%llx\n",
181 ent->start);
182 ret = -1;
183 continue;
184 }
185
186 snprintf(buf: ent->name, size: 16, fmt: "%08x", ent->nid);
187 dir = debugfs_create_dir(name: ent->name, parent: memtrace_debugfs_dir);
188
189 ent->dir = dir;
190 debugfs_create_file_unsafe(name: "trace", mode: 0600, parent: dir, data: ent, fops: &memtrace_fops);
191 debugfs_create_x64(name: "start", mode: 0400, parent: dir, value: &ent->start);
192 debugfs_create_x64(name: "size", mode: 0400, parent: dir, value: &ent->size);
193 }
194
195 return ret;
196}
197
198static int memtrace_free(int nid, u64 start, u64 size)
199{
200 struct mhp_params params = { .pgprot = PAGE_KERNEL };
201 const unsigned long nr_pages = PHYS_PFN(size);
202 const unsigned long start_pfn = PHYS_PFN(start);
203 unsigned long pfn;
204 int ret;
205
206 ret = arch_create_linear_mapping(nid, start, size, params: &params);
207 if (ret)
208 return ret;
209
210 for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
211 __ClearPageOffline(pfn_to_page(pfn));
212
213 free_contig_range(pfn: start_pfn, nr_pages);
214 return 0;
215}
216
217/*
218 * Iterate through the chunks of memory we allocated and attempt to expose
219 * them back to the kernel.
220 */
221static int memtrace_free_regions(void)
222{
223 int i, ret = 0;
224 struct memtrace_entry *ent;
225
226 for (i = memtrace_array_nr - 1; i >= 0; i--) {
227 ent = &memtrace_array[i];
228
229 /* We have freed this chunk previously */
230 if (ent->nid == NUMA_NO_NODE)
231 continue;
232
233 /* Remove from io mappings */
234 if (ent->mem) {
235 iounmap(addr: ent->mem);
236 ent->mem = 0;
237 }
238
239 if (memtrace_free(nid: ent->nid, start: ent->start, size: ent->size)) {
240 pr_err("Failed to free trace memory on node %d\n",
241 ent->nid);
242 ret += 1;
243 continue;
244 }
245
246 /*
247 * Memory was freed successfully so clean up references to it
248 * so on reentry we can tell that this chunk was freed.
249 */
250 debugfs_remove_recursive(dentry: ent->dir);
251 pr_info("Freed trace memory back on node %d\n", ent->nid);
252 ent->size = ent->start = ent->nid = NUMA_NO_NODE;
253 }
254 if (ret)
255 return ret;
256
257 /* If all chunks of memory were freed successfully, reset globals */
258 kfree(objp: memtrace_array);
259 memtrace_array = NULL;
260 memtrace_size = 0;
261 memtrace_array_nr = 0;
262 return 0;
263}
264
265static int memtrace_enable_set(void *data, u64 val)
266{
267 int rc = -EAGAIN;
268 u64 bytes;
269
270 /*
271 * Don't attempt to do anything if size isn't aligned to a memory
272 * block or equal to zero.
273 */
274 bytes = memory_block_size_bytes();
275 if (val & (bytes - 1)) {
276 pr_err("Value must be aligned with 0x%llx\n", bytes);
277 return -EINVAL;
278 }
279
280 mutex_lock(&memtrace_mutex);
281
282 /* Free all previously allocated memory. */
283 if (memtrace_size && memtrace_free_regions())
284 goto out_unlock;
285
286 if (!val) {
287 rc = 0;
288 goto out_unlock;
289 }
290
291 /* Allocate memory. */
292 if (memtrace_init_regions_runtime(size: val))
293 goto out_unlock;
294
295 if (memtrace_init_debugfs())
296 goto out_unlock;
297
298 memtrace_size = val;
299 rc = 0;
300out_unlock:
301 mutex_unlock(lock: &memtrace_mutex);
302 return rc;
303}
304
305static int memtrace_enable_get(void *data, u64 *val)
306{
307 *val = memtrace_size;
308 return 0;
309}
310
311DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
312 memtrace_enable_set, "0x%016llx\n");
313
314static int memtrace_init(void)
315{
316 memtrace_debugfs_dir = debugfs_create_dir(name: "memtrace",
317 parent: arch_debugfs_dir);
318
319 debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
320 NULL, &memtrace_init_fops);
321
322 return 0;
323}
324machine_device_initcall(powernv, memtrace_init);
325

source code of linux/arch/powerpc/platforms/powernv/memtrace.c