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(ubuf, count, ppos, ent->mem, 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
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
63static 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 */
80static 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
91static 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
111static 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
146static 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
181static struct dentry *memtrace_debugfs_dir;
182
183static 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
213static 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, &params);
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 */
236static 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
280static 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;
315out_unlock:
316	mutex_unlock(&memtrace_mutex);
317	return rc;
318}
319
320static int memtrace_enable_get(void *data, u64 *val)
321{
322	*val = memtrace_size;
323	return 0;
324}
325
326DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
327					memtrace_enable_set, "0x%016llx\n");
328
329static 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}
339machine_device_initcall(powernv, memtrace_init);
340