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 #include <asm/cacheflush.h>
23 
24 /* This enables us to keep track of the memory removed from each node. */
25 struct memtrace_entry {
26 	void *mem;
27 	u64 start;
28 	u64 size;
29 	u32 nid;
30 	struct dentry *dir;
31 	char name[16];
32 };
33 
34 static DEFINE_MUTEX(memtrace_mutex);
35 static u64 memtrace_size;
36 
37 static struct memtrace_entry *memtrace_array;
38 static unsigned int memtrace_array_nr;
39 
40 
41 static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
42 			     size_t count, loff_t *ppos)
43 {
44 	struct memtrace_entry *ent = filp->private_data;
45 
46 	return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);
47 }
48 
49 static int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)
50 {
51 	struct memtrace_entry *ent = filp->private_data;
52 
53 	if (ent->size < vma->vm_end - vma->vm_start)
54 		return -EINVAL;
55 
56 	if (vma->vm_pgoff << PAGE_SHIFT >= ent->size)
57 		return -EINVAL;
58 
59 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
60 	return remap_pfn_range(vma, vma->vm_start, PHYS_PFN(ent->start) + vma->vm_pgoff,
61 			       vma->vm_end - vma->vm_start, vma->vm_page_prot);
62 }
63 
64 static const struct file_operations memtrace_fops = {
65 	.llseek = default_llseek,
66 	.read	= memtrace_read,
67 	.open	= simple_open,
68 	.mmap   = memtrace_mmap,
69 };
70 
71 #define FLUSH_CHUNK_SIZE SZ_1G
72 /**
73  * flush_dcache_range_chunked(): Write any modified data cache blocks out to
74  * memory and invalidate them, in chunks of up to FLUSH_CHUNK_SIZE
75  * Does not invalidate the corresponding instruction cache blocks.
76  *
77  * @start: the start address
78  * @stop: the stop address (exclusive)
79  * @chunk: the max size of the chunks
80  */
81 static void flush_dcache_range_chunked(unsigned long start, unsigned long stop,
82 				       unsigned long chunk)
83 {
84 	unsigned long i;
85 
86 	for (i = start; i < stop; i += chunk) {
87 		flush_dcache_range(i, min(stop, i + chunk));
88 		cond_resched();
89 	}
90 }
91 
92 static void memtrace_clear_range(unsigned long start_pfn,
93 				 unsigned long nr_pages)
94 {
95 	unsigned long pfn;
96 
97 	/* As HIGHMEM does not apply, use clear_page() directly. */
98 	for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) {
99 		if (IS_ALIGNED(pfn, PAGES_PER_SECTION))
100 			cond_resched();
101 		clear_page(__va(PFN_PHYS(pfn)));
102 	}
103 	/*
104 	 * Before we go ahead and use this range as cache inhibited range
105 	 * flush the cache.
106 	 */
107 	flush_dcache_range_chunked(PFN_PHYS(start_pfn),
108 				   PFN_PHYS(start_pfn + nr_pages),
109 				   FLUSH_CHUNK_SIZE);
110 }
111 
112 static u64 memtrace_alloc_node(u32 nid, u64 size)
113 {
114 	const unsigned long nr_pages = PHYS_PFN(size);
115 	unsigned long pfn, start_pfn;
116 	struct page *page;
117 
118 	/*
119 	 * Trace memory needs to be aligned to the size, which is guaranteed
120 	 * by alloc_contig_pages().
121 	 */
122 	page = alloc_contig_pages(nr_pages, GFP_KERNEL | __GFP_THISNODE |
123 				  __GFP_NOWARN, nid, NULL);
124 	if (!page)
125 		return 0;
126 	start_pfn = page_to_pfn(page);
127 
128 	/*
129 	 * Clear the range while we still have a linear mapping.
130 	 *
131 	 * TODO: use __GFP_ZERO with alloc_contig_pages() once supported.
132 	 */
133 	memtrace_clear_range(start_pfn, nr_pages);
134 
135 	/*
136 	 * Set pages PageOffline(), to indicate that nobody (e.g., hibernation,
137 	 * dumping, ...) should be touching these pages.
138 	 */
139 	for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
140 		__SetPageOffline(pfn_to_page(pfn));
141 
142 	arch_remove_linear_mapping(PFN_PHYS(start_pfn), size);
143 
144 	return PFN_PHYS(start_pfn);
145 }
146 
147 static int memtrace_init_regions_runtime(u64 size)
148 {
149 	u32 nid;
150 	u64 m;
151 
152 	memtrace_array = kcalloc(num_online_nodes(),
153 				sizeof(struct memtrace_entry), GFP_KERNEL);
154 	if (!memtrace_array) {
155 		pr_err("Failed to allocate memtrace_array\n");
156 		return -EINVAL;
157 	}
158 
159 	for_each_online_node(nid) {
160 		m = memtrace_alloc_node(nid, size);
161 
162 		/*
163 		 * A node might not have any local memory, so warn but
164 		 * continue on.
165 		 */
166 		if (!m) {
167 			pr_err("Failed to allocate trace memory on node %d\n", nid);
168 			continue;
169 		}
170 
171 		pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
172 
173 		memtrace_array[memtrace_array_nr].start = m;
174 		memtrace_array[memtrace_array_nr].size = size;
175 		memtrace_array[memtrace_array_nr].nid = nid;
176 		memtrace_array_nr++;
177 	}
178 
179 	return 0;
180 }
181 
182 static struct dentry *memtrace_debugfs_dir;
183 
184 static int memtrace_init_debugfs(void)
185 {
186 	int ret = 0;
187 	int i;
188 
189 	for (i = 0; i < memtrace_array_nr; i++) {
190 		struct dentry *dir;
191 		struct memtrace_entry *ent = &memtrace_array[i];
192 
193 		ent->mem = ioremap(ent->start, ent->size);
194 		/* Warn but continue on */
195 		if (!ent->mem) {
196 			pr_err("Failed to map trace memory at 0x%llx\n",
197 				 ent->start);
198 			ret = -1;
199 			continue;
200 		}
201 
202 		snprintf(ent->name, 16, "%08x", ent->nid);
203 		dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
204 
205 		ent->dir = dir;
206 		debugfs_create_file_unsafe("trace", 0600, dir, ent, &memtrace_fops);
207 		debugfs_create_x64("start", 0400, dir, &ent->start);
208 		debugfs_create_x64("size", 0400, dir, &ent->size);
209 	}
210 
211 	return ret;
212 }
213 
214 static int memtrace_free(int nid, u64 start, u64 size)
215 {
216 	struct mhp_params params = { .pgprot = PAGE_KERNEL };
217 	const unsigned long nr_pages = PHYS_PFN(size);
218 	const unsigned long start_pfn = PHYS_PFN(start);
219 	unsigned long pfn;
220 	int ret;
221 
222 	ret = arch_create_linear_mapping(nid, start, size, &params);
223 	if (ret)
224 		return ret;
225 
226 	for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
227 		__ClearPageOffline(pfn_to_page(pfn));
228 
229 	free_contig_range(start_pfn, nr_pages);
230 	return 0;
231 }
232 
233 /*
234  * Iterate through the chunks of memory we allocated and attempt to expose
235  * them back to the kernel.
236  */
237 static int memtrace_free_regions(void)
238 {
239 	int i, ret = 0;
240 	struct memtrace_entry *ent;
241 
242 	for (i = memtrace_array_nr - 1; i >= 0; i--) {
243 		ent = &memtrace_array[i];
244 
245 		/* We have freed this chunk previously */
246 		if (ent->nid == NUMA_NO_NODE)
247 			continue;
248 
249 		/* Remove from io mappings */
250 		if (ent->mem) {
251 			iounmap(ent->mem);
252 			ent->mem = 0;
253 		}
254 
255 		if (memtrace_free(ent->nid, ent->start, ent->size)) {
256 			pr_err("Failed to free trace memory on node %d\n",
257 				ent->nid);
258 			ret += 1;
259 			continue;
260 		}
261 
262 		/*
263 		 * Memory was freed successfully so clean up references to it
264 		 * so on reentry we can tell that this chunk was freed.
265 		 */
266 		debugfs_remove_recursive(ent->dir);
267 		pr_info("Freed trace memory back on 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 freed 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 
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 	/* Free all previously allocated memory. */
299 	if (memtrace_size && memtrace_free_regions())
300 		goto out_unlock;
301 
302 	if (!val) {
303 		rc = 0;
304 		goto out_unlock;
305 	}
306 
307 	/* Allocate memory. */
308 	if (memtrace_init_regions_runtime(val))
309 		goto out_unlock;
310 
311 	if (memtrace_init_debugfs())
312 		goto out_unlock;
313 
314 	memtrace_size = val;
315 	rc = 0;
316 out_unlock:
317 	mutex_unlock(&memtrace_mutex);
318 	return rc;
319 }
320 
321 static int memtrace_enable_get(void *data, u64 *val)
322 {
323 	*val = memtrace_size;
324 	return 0;
325 }
326 
327 DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
328 					memtrace_enable_set, "0x%016llx\n");
329 
330 static int memtrace_init(void)
331 {
332 	memtrace_debugfs_dir = debugfs_create_dir("memtrace",
333 						  powerpc_debugfs_root);
334 
335 	debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
336 			    NULL, &memtrace_init_fops);
337 
338 	return 0;
339 }
340 machine_device_initcall(powernv, memtrace_init);
341