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11#include <linux/gfp.h>
12#include <linux/hash.h>
13#include <linux/kernel.h>
14#include <linux/mm.h>
15#include <linux/percpu.h>
16#include <linux/printk.h>
17#include <linux/shrinker.h>
18#include <linux/slab.h>
19#include <linux/srcu.h>
20#include <linux/string.h>
21#include <linux/types.h>
22#include <linux/cpuhotplug.h>
23
24#include "../slab.h"
25#include "kasan.h"
26
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30
31
32
33struct qlist_head {
34 struct qlist_node *head;
35 struct qlist_node *tail;
36 size_t bytes;
37 bool offline;
38};
39
40#define QLIST_INIT { NULL, NULL, 0 }
41
42static bool qlist_empty(struct qlist_head *q)
43{
44 return !q->head;
45}
46
47static void qlist_init(struct qlist_head *q)
48{
49 q->head = q->tail = NULL;
50 q->bytes = 0;
51}
52
53static void qlist_put(struct qlist_head *q, struct qlist_node *qlink,
54 size_t size)
55{
56 if (unlikely(qlist_empty(q)))
57 q->head = qlink;
58 else
59 q->tail->next = qlink;
60 q->tail = qlink;
61 qlink->next = NULL;
62 q->bytes += size;
63}
64
65static void qlist_move_all(struct qlist_head *from, struct qlist_head *to)
66{
67 if (unlikely(qlist_empty(from)))
68 return;
69
70 if (qlist_empty(to)) {
71 *to = *from;
72 qlist_init(from);
73 return;
74 }
75
76 to->tail->next = from->head;
77 to->tail = from->tail;
78 to->bytes += from->bytes;
79
80 qlist_init(from);
81}
82
83#define QUARANTINE_PERCPU_SIZE (1 << 20)
84#define QUARANTINE_BATCHES \
85 (1024 > 4 * CONFIG_NR_CPUS ? 1024 : 4 * CONFIG_NR_CPUS)
86
87
88
89
90
91static DEFINE_PER_CPU(struct qlist_head, cpu_quarantine);
92
93
94static struct qlist_head global_quarantine[QUARANTINE_BATCHES];
95static int quarantine_head;
96static int quarantine_tail;
97
98static unsigned long quarantine_size;
99static DEFINE_RAW_SPINLOCK(quarantine_lock);
100DEFINE_STATIC_SRCU(remove_cache_srcu);
101
102
103static unsigned long quarantine_max_size;
104
105
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107
108
109static unsigned long quarantine_batch_size;
110
111
112
113
114
115
116#define QUARANTINE_FRACTION 32
117
118static struct kmem_cache *qlink_to_cache(struct qlist_node *qlink)
119{
120 return virt_to_head_page(qlink)->slab_cache;
121}
122
123static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache)
124{
125 struct kasan_free_meta *free_info =
126 container_of(qlink, struct kasan_free_meta,
127 quarantine_link);
128
129 return ((void *)free_info) - cache->kasan_info.free_meta_offset;
130}
131
132static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
133{
134 void *object = qlink_to_object(qlink, cache);
135 unsigned long flags;
136
137 if (IS_ENABLED(CONFIG_SLAB))
138 local_irq_save(flags);
139
140
141
142
143
144 *(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREE;
145
146 ___cache_free(cache, object, _THIS_IP_);
147
148 if (IS_ENABLED(CONFIG_SLAB))
149 local_irq_restore(flags);
150}
151
152static void qlist_free_all(struct qlist_head *q, struct kmem_cache *cache)
153{
154 struct qlist_node *qlink;
155
156 if (unlikely(qlist_empty(q)))
157 return;
158
159 qlink = q->head;
160 while (qlink) {
161 struct kmem_cache *obj_cache =
162 cache ? cache : qlink_to_cache(qlink);
163 struct qlist_node *next = qlink->next;
164
165 qlink_free(qlink, obj_cache);
166 qlink = next;
167 }
168 qlist_init(q);
169}
170
171bool kasan_quarantine_put(struct kmem_cache *cache, void *object)
172{
173 unsigned long flags;
174 struct qlist_head *q;
175 struct qlist_head temp = QLIST_INIT;
176 struct kasan_free_meta *meta = kasan_get_free_meta(cache, object);
177
178
179
180
181
182 if (!meta)
183 return false;
184
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190
191
192
193 local_irq_save(flags);
194
195 q = this_cpu_ptr(&cpu_quarantine);
196 if (q->offline) {
197 local_irq_restore(flags);
198 return false;
199 }
200 qlist_put(q, &meta->quarantine_link, cache->size);
201 if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) {
202 qlist_move_all(q, &temp);
203
204 raw_spin_lock(&quarantine_lock);
205 WRITE_ONCE(quarantine_size, quarantine_size + temp.bytes);
206 qlist_move_all(&temp, &global_quarantine[quarantine_tail]);
207 if (global_quarantine[quarantine_tail].bytes >=
208 READ_ONCE(quarantine_batch_size)) {
209 int new_tail;
210
211 new_tail = quarantine_tail + 1;
212 if (new_tail == QUARANTINE_BATCHES)
213 new_tail = 0;
214 if (new_tail != quarantine_head)
215 quarantine_tail = new_tail;
216 }
217 raw_spin_unlock(&quarantine_lock);
218 }
219
220 local_irq_restore(flags);
221
222 return true;
223}
224
225void kasan_quarantine_reduce(void)
226{
227 size_t total_size, new_quarantine_size, percpu_quarantines;
228 unsigned long flags;
229 int srcu_idx;
230 struct qlist_head to_free = QLIST_INIT;
231
232 if (likely(READ_ONCE(quarantine_size) <=
233 READ_ONCE(quarantine_max_size)))
234 return;
235
236
237
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240
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242
243
244
245 srcu_idx = srcu_read_lock(&remove_cache_srcu);
246 raw_spin_lock_irqsave(&quarantine_lock, flags);
247
248
249
250
251
252 total_size = (totalram_pages() << PAGE_SHIFT) /
253 QUARANTINE_FRACTION;
254 percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus();
255 new_quarantine_size = (total_size < percpu_quarantines) ?
256 0 : total_size - percpu_quarantines;
257 WRITE_ONCE(quarantine_max_size, new_quarantine_size);
258
259 WRITE_ONCE(quarantine_batch_size, max((size_t)QUARANTINE_PERCPU_SIZE,
260 2 * total_size / QUARANTINE_BATCHES));
261
262 if (likely(quarantine_size > quarantine_max_size)) {
263 qlist_move_all(&global_quarantine[quarantine_head], &to_free);
264 WRITE_ONCE(quarantine_size, quarantine_size - to_free.bytes);
265 quarantine_head++;
266 if (quarantine_head == QUARANTINE_BATCHES)
267 quarantine_head = 0;
268 }
269
270 raw_spin_unlock_irqrestore(&quarantine_lock, flags);
271
272 qlist_free_all(&to_free, NULL);
273 srcu_read_unlock(&remove_cache_srcu, srcu_idx);
274}
275
276static void qlist_move_cache(struct qlist_head *from,
277 struct qlist_head *to,
278 struct kmem_cache *cache)
279{
280 struct qlist_node *curr;
281
282 if (unlikely(qlist_empty(from)))
283 return;
284
285 curr = from->head;
286 qlist_init(from);
287 while (curr) {
288 struct qlist_node *next = curr->next;
289 struct kmem_cache *obj_cache = qlink_to_cache(curr);
290
291 if (obj_cache == cache)
292 qlist_put(to, curr, obj_cache->size);
293 else
294 qlist_put(from, curr, obj_cache->size);
295
296 curr = next;
297 }
298}
299
300static void per_cpu_remove_cache(void *arg)
301{
302 struct kmem_cache *cache = arg;
303 struct qlist_head to_free = QLIST_INIT;
304 struct qlist_head *q;
305
306 q = this_cpu_ptr(&cpu_quarantine);
307 qlist_move_cache(q, &to_free, cache);
308 qlist_free_all(&to_free, cache);
309}
310
311
312void kasan_quarantine_remove_cache(struct kmem_cache *cache)
313{
314 unsigned long flags, i;
315 struct qlist_head to_free = QLIST_INIT;
316
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320
321
322
323
324 on_each_cpu(per_cpu_remove_cache, cache, 1);
325
326 raw_spin_lock_irqsave(&quarantine_lock, flags);
327 for (i = 0; i < QUARANTINE_BATCHES; i++) {
328 if (qlist_empty(&global_quarantine[i]))
329 continue;
330 qlist_move_cache(&global_quarantine[i], &to_free, cache);
331
332 raw_spin_unlock_irqrestore(&quarantine_lock, flags);
333 cond_resched();
334 raw_spin_lock_irqsave(&quarantine_lock, flags);
335 }
336 raw_spin_unlock_irqrestore(&quarantine_lock, flags);
337
338 qlist_free_all(&to_free, cache);
339
340 synchronize_srcu(&remove_cache_srcu);
341}
342
343static int kasan_cpu_online(unsigned int cpu)
344{
345 this_cpu_ptr(&cpu_quarantine)->offline = false;
346 return 0;
347}
348
349static int kasan_cpu_offline(unsigned int cpu)
350{
351 struct qlist_head *q;
352
353 q = this_cpu_ptr(&cpu_quarantine);
354
355
356
357
358 WRITE_ONCE(q->offline, true);
359 barrier();
360 qlist_free_all(q, NULL);
361 return 0;
362}
363
364static int __init kasan_cpu_quarantine_init(void)
365{
366 int ret = 0;
367
368 ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mm/kasan:online",
369 kasan_cpu_online, kasan_cpu_offline);
370 if (ret < 0)
371 pr_err("kasan cpu quarantine register failed [%d]\n", ret);
372 return ret;
373}
374late_initcall(kasan_cpu_quarantine_init);
375