summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/platforms/powernv/memtrace.c
blob: 51dc398ae3f7a2431b39f6705a4cfc495a378aeb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
/*
 * Copyright (C) IBM Corporation, 2014, 2017
 * Anton Blanchard, Rashmica Gupta.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#define pr_fmt(fmt) "memtrace: " fmt

#include <linux/bitops.h>
#include <linux/string.h>
#include <linux/memblock.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/slab.h>
#include <linux/memory.h>
#include <linux/memory_hotplug.h>
#include <asm/machdep.h>
#include <asm/debugfs.h>

/* This enables us to keep track of the memory removed from each node. */
struct memtrace_entry {
	void *mem;
	u64 start;
	u64 size;
	u32 nid;
	struct dentry *dir;
	char name[16];
};

static u64 memtrace_size;

static struct memtrace_entry *memtrace_array;
static unsigned int memtrace_array_nr;


static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
			     size_t count, loff_t *ppos)
{
	struct memtrace_entry *ent = filp->private_data;

	return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);
}

static const struct file_operations memtrace_fops = {
	.llseek = default_llseek,
	.read	= memtrace_read,
	.open	= simple_open,
};

static int check_memblock_online(struct memory_block *mem, void *arg)
{
	if (mem->state != MEM_ONLINE)
		return -1;

	return 0;
}

static int change_memblock_state(struct memory_block *mem, void *arg)
{
	unsigned long state = (unsigned long)arg;

	mem->state = state;

	return 0;
}

static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
{
	u64 end_pfn = start_pfn + nr_pages - 1;

	if (walk_memory_range(start_pfn, end_pfn, NULL,
	    check_memblock_online))
		return false;

	walk_memory_range(start_pfn, end_pfn, (void *)MEM_GOING_OFFLINE,
			  change_memblock_state);

	if (offline_pages(start_pfn, nr_pages)) {
		walk_memory_range(start_pfn, end_pfn, (void *)MEM_ONLINE,
				  change_memblock_state);
		return false;
	}

	walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
			  change_memblock_state);

	lock_device_hotplug();
	remove_memory(nid, start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
	unlock_device_hotplug();

	return true;
}

static u64 memtrace_alloc_node(u32 nid, u64 size)
{
	u64 start_pfn, end_pfn, nr_pages;
	u64 base_pfn;

	if (!node_spanned_pages(nid))
		return 0;

	start_pfn = node_start_pfn(nid);
	end_pfn = node_end_pfn(nid);
	nr_pages = size >> PAGE_SHIFT;

	/* Trace memory needs to be aligned to the size */
	end_pfn = round_down(end_pfn - nr_pages, nr_pages);

	for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) {
		if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true)
			return base_pfn << PAGE_SHIFT;
	}

	return 0;
}

static int memtrace_init_regions_runtime(u64 size)
{
	u32 nid;
	u64 m;

	memtrace_array = kcalloc(num_online_nodes(),
				sizeof(struct memtrace_entry), GFP_KERNEL);
	if (!memtrace_array) {
		pr_err("Failed to allocate memtrace_array\n");
		return -EINVAL;
	}

	for_each_online_node(nid) {
		m = memtrace_alloc_node(nid, size);

		/*
		 * A node might not have any local memory, so warn but
		 * continue on.
		 */
		if (!m) {
			pr_err("Failed to allocate trace memory on node %d\n", nid);
			continue;
		}

		pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);

		memtrace_array[memtrace_array_nr].start = m;
		memtrace_array[memtrace_array_nr].size = size;
		memtrace_array[memtrace_array_nr].nid = nid;
		memtrace_array_nr++;
	}

	return 0;
}

static struct dentry *memtrace_debugfs_dir;

static int memtrace_init_debugfs(void)
{
	int ret = 0;
	int i;

	for (i = 0; i < memtrace_array_nr; i++) {
		struct dentry *dir;
		struct memtrace_entry *ent = &memtrace_array[i];

		ent->mem = ioremap(ent->start, ent->size);
		/* Warn but continue on */
		if (!ent->mem) {
			pr_err("Failed to map trace memory at 0x%llx\n",
				 ent->start);
			ret = -1;
			continue;
		}

		snprintf(ent->name, 16, "%08x", ent->nid);
		dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
		if (!dir) {
			pr_err("Failed to create debugfs directory for node %d\n",
				ent->nid);
			return -1;
		}

		ent->dir = dir;
		debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
		debugfs_create_x64("start", 0400, dir, &ent->start);
		debugfs_create_x64("size", 0400, dir, &ent->size);
	}

	return ret;
}

static int online_mem_block(struct memory_block *mem, void *arg)
{
	return device_online(&mem->dev);
}

/*
 * Iterate through the chunks of memory we have removed from the kernel
 * and attempt to add them back to the kernel.
 */
static int memtrace_online(void)
{
	int i, ret = 0;
	struct memtrace_entry *ent;

	for (i = memtrace_array_nr - 1; i >= 0; i--) {
		ent = &memtrace_array[i];

		/* We have onlined this chunk previously */
		if (ent->nid == -1)
			continue;

		/* Remove from io mappings */
		if (ent->mem) {
			iounmap(ent->mem);
			ent->mem = 0;
		}

		if (add_memory(ent->nid, ent->start, ent->size)) {
			pr_err("Failed to add trace memory to node %d\n",
				ent->nid);
			ret += 1;
			continue;
		}

		/*
		 * If kernel isn't compiled with the auto online option
		 * we need to online the memory ourselves.
		 */
		if (!memhp_auto_online) {
			walk_memory_range(PFN_DOWN(ent->start),
					  PFN_UP(ent->start + ent->size - 1),
					  NULL, online_mem_block);
		}

		/*
		 * Memory was added successfully so clean up references to it
		 * so on reentry we can tell that this chunk was added.
		 */
		debugfs_remove_recursive(ent->dir);
		pr_info("Added trace memory back to node %d\n", ent->nid);
		ent->size = ent->start = ent->nid = -1;
	}
	if (ret)
		return ret;

	/* If all chunks of memory were added successfully, reset globals */
	kfree(memtrace_array);
	memtrace_array = NULL;
	memtrace_size = 0;
	memtrace_array_nr = 0;
	return 0;
}

static int memtrace_enable_set(void *data, u64 val)
{
	u64 bytes;

	/*
	 * Don't attempt to do anything if size isn't aligned to a memory
	 * block or equal to zero.
	 */
	bytes = memory_block_size_bytes();
	if (val & (bytes - 1)) {
		pr_err("Value must be aligned with 0x%llx\n", bytes);
		return -EINVAL;
	}

	/* Re-add/online previously removed/offlined memory */
	if (memtrace_size) {
		if (memtrace_online())
			return -EAGAIN;
	}

	if (!val)
		return 0;

	/* Offline and remove memory */
	if (memtrace_init_regions_runtime(val))
		return -EINVAL;

	if (memtrace_init_debugfs())
		return -EINVAL;

	memtrace_size = val;

	return 0;
}

static int memtrace_enable_get(void *data, u64 *val)
{
	*val = memtrace_size;
	return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
					memtrace_enable_set, "0x%016llx\n");

static int memtrace_init(void)
{
	memtrace_debugfs_dir = debugfs_create_dir("memtrace",
						  powerpc_debugfs_root);
	if (!memtrace_debugfs_dir)
		return -1;

	debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
			    NULL, &memtrace_init_fops);

	return 0;
}
machine_device_initcall(powernv, memtrace_init);