1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* Support for MMIO probes. |
3 | * Benefit many code from kprobes |
4 | * (C) 2002 Louis Zhuang <louis.zhuang@intel.com>. |
5 | * 2007 Alexander Eichner |
6 | * 2008 Pekka Paalanen <pq@iki.fi> |
7 | */ |
8 | |
9 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
10 | |
11 | #include <linux/list.h> |
12 | #include <linux/rculist.h> |
13 | #include <linux/spinlock.h> |
14 | #include <linux/hash.h> |
15 | #include <linux/export.h> |
16 | #include <linux/kernel.h> |
17 | #include <linux/uaccess.h> |
18 | #include <linux/ptrace.h> |
19 | #include <linux/preempt.h> |
20 | #include <linux/percpu.h> |
21 | #include <linux/kdebug.h> |
22 | #include <linux/mutex.h> |
23 | #include <linux/io.h> |
24 | #include <linux/slab.h> |
25 | #include <asm/cacheflush.h> |
26 | #include <asm/tlbflush.h> |
27 | #include <linux/errno.h> |
28 | #include <asm/debugreg.h> |
29 | #include <linux/mmiotrace.h> |
30 | |
31 | #define KMMIO_PAGE_HASH_BITS 4 |
32 | #define KMMIO_PAGE_TABLE_SIZE (1 << KMMIO_PAGE_HASH_BITS) |
33 | |
34 | struct kmmio_fault_page { |
35 | struct list_head list; |
36 | struct kmmio_fault_page *release_next; |
37 | unsigned long addr; /* the requested address */ |
38 | pteval_t old_presence; /* page presence prior to arming */ |
39 | bool armed; |
40 | |
41 | /* |
42 | * Number of times this page has been registered as a part |
43 | * of a probe. If zero, page is disarmed and this may be freed. |
44 | * Used only by writers (RCU) and post_kmmio_handler(). |
45 | * Protected by kmmio_lock, when linked into kmmio_page_table. |
46 | */ |
47 | int count; |
48 | |
49 | bool scheduled_for_release; |
50 | }; |
51 | |
52 | struct kmmio_delayed_release { |
53 | struct rcu_head rcu; |
54 | struct kmmio_fault_page *release_list; |
55 | }; |
56 | |
57 | struct kmmio_context { |
58 | struct kmmio_fault_page *fpage; |
59 | struct kmmio_probe *probe; |
60 | unsigned long saved_flags; |
61 | unsigned long addr; |
62 | int active; |
63 | }; |
64 | |
65 | /* |
66 | * The kmmio_lock is taken in int3 context, which is treated as NMI context. |
67 | * This causes lockdep to complain about it bein in both NMI and normal |
68 | * context. Hide it from lockdep, as it should not have any other locks |
69 | * taken under it, and this is only enabled for debugging mmio anyway. |
70 | */ |
71 | static arch_spinlock_t kmmio_lock = __ARCH_SPIN_LOCK_UNLOCKED; |
72 | |
73 | /* Protected by kmmio_lock */ |
74 | unsigned int kmmio_count; |
75 | |
76 | /* Read-protected by RCU, write-protected by kmmio_lock. */ |
77 | static struct list_head kmmio_page_table[KMMIO_PAGE_TABLE_SIZE]; |
78 | static LIST_HEAD(kmmio_probes); |
79 | |
80 | static struct list_head *kmmio_page_list(unsigned long addr) |
81 | { |
82 | unsigned int l; |
83 | pte_t *pte = lookup_address(address: addr, level: &l); |
84 | |
85 | if (!pte) |
86 | return NULL; |
87 | addr &= page_level_mask(level: l); |
88 | |
89 | return &kmmio_page_table[hash_long(addr, KMMIO_PAGE_HASH_BITS)]; |
90 | } |
91 | |
92 | /* Accessed per-cpu */ |
93 | static DEFINE_PER_CPU(struct kmmio_context, kmmio_ctx); |
94 | |
95 | /* |
96 | * this is basically a dynamic stabbing problem: |
97 | * Could use the existing prio tree code or |
98 | * Possible better implementations: |
99 | * The Interval Skip List: A Data Structure for Finding All Intervals That |
100 | * Overlap a Point (might be simple) |
101 | * Space Efficient Dynamic Stabbing with Fast Queries - Mikkel Thorup |
102 | */ |
103 | /* Get the kmmio at this addr (if any). You must be holding RCU read lock. */ |
104 | static struct kmmio_probe *get_kmmio_probe(unsigned long addr) |
105 | { |
106 | struct kmmio_probe *p; |
107 | list_for_each_entry_rcu(p, &kmmio_probes, list) { |
108 | if (addr >= p->addr && addr < (p->addr + p->len)) |
109 | return p; |
110 | } |
111 | return NULL; |
112 | } |
113 | |
114 | /* You must be holding RCU read lock. */ |
115 | static struct kmmio_fault_page *get_kmmio_fault_page(unsigned long addr) |
116 | { |
117 | struct list_head *head; |
118 | struct kmmio_fault_page *f; |
119 | unsigned int l; |
120 | pte_t *pte = lookup_address(address: addr, level: &l); |
121 | |
122 | if (!pte) |
123 | return NULL; |
124 | addr &= page_level_mask(level: l); |
125 | head = kmmio_page_list(addr); |
126 | list_for_each_entry_rcu(f, head, list) { |
127 | if (f->addr == addr) |
128 | return f; |
129 | } |
130 | return NULL; |
131 | } |
132 | |
133 | static void clear_pmd_presence(pmd_t *pmd, bool clear, pmdval_t *old) |
134 | { |
135 | pmd_t new_pmd; |
136 | pmdval_t v = pmd_val(pmd: *pmd); |
137 | if (clear) { |
138 | *old = v; |
139 | new_pmd = pmd_mkinvalid(pmd: *pmd); |
140 | } else { |
141 | /* Presume this has been called with clear==true previously */ |
142 | new_pmd = __pmd(val: *old); |
143 | } |
144 | set_pmd(pmdp: pmd, pmd: new_pmd); |
145 | } |
146 | |
147 | static void clear_pte_presence(pte_t *pte, bool clear, pteval_t *old) |
148 | { |
149 | pteval_t v = pte_val(pte: *pte); |
150 | if (clear) { |
151 | *old = v; |
152 | /* Nothing should care about address */ |
153 | pte_clear(mm: &init_mm, addr: 0, ptep: pte); |
154 | } else { |
155 | /* Presume this has been called with clear==true previously */ |
156 | set_pte_atomic(ptep: pte, pte: __pte(val: *old)); |
157 | } |
158 | } |
159 | |
160 | static int clear_page_presence(struct kmmio_fault_page *f, bool clear) |
161 | { |
162 | unsigned int level; |
163 | pte_t *pte = lookup_address(address: f->addr, level: &level); |
164 | |
165 | if (!pte) { |
166 | pr_err("no pte for addr 0x%08lx\n" , f->addr); |
167 | return -1; |
168 | } |
169 | |
170 | switch (level) { |
171 | case PG_LEVEL_2M: |
172 | clear_pmd_presence(pmd: (pmd_t *)pte, clear, old: &f->old_presence); |
173 | break; |
174 | case PG_LEVEL_4K: |
175 | clear_pte_presence(pte, clear, old: &f->old_presence); |
176 | break; |
177 | default: |
178 | pr_err("unexpected page level 0x%x.\n" , level); |
179 | return -1; |
180 | } |
181 | |
182 | flush_tlb_one_kernel(addr: f->addr); |
183 | return 0; |
184 | } |
185 | |
186 | /* |
187 | * Mark the given page as not present. Access to it will trigger a fault. |
188 | * |
189 | * Struct kmmio_fault_page is protected by RCU and kmmio_lock, but the |
190 | * protection is ignored here. RCU read lock is assumed held, so the struct |
191 | * will not disappear unexpectedly. Furthermore, the caller must guarantee, |
192 | * that double arming the same virtual address (page) cannot occur. |
193 | * |
194 | * Double disarming on the other hand is allowed, and may occur when a fault |
195 | * and mmiotrace shutdown happen simultaneously. |
196 | */ |
197 | static int arm_kmmio_fault_page(struct kmmio_fault_page *f) |
198 | { |
199 | int ret; |
200 | WARN_ONCE(f->armed, KERN_ERR pr_fmt("kmmio page already armed.\n" )); |
201 | if (f->armed) { |
202 | pr_warn("double-arm: addr 0x%08lx, ref %d, old %d\n" , |
203 | f->addr, f->count, !!f->old_presence); |
204 | } |
205 | ret = clear_page_presence(f, clear: true); |
206 | WARN_ONCE(ret < 0, KERN_ERR pr_fmt("arming at 0x%08lx failed.\n" ), |
207 | f->addr); |
208 | f->armed = true; |
209 | return ret; |
210 | } |
211 | |
212 | /** Restore the given page to saved presence state. */ |
213 | static void disarm_kmmio_fault_page(struct kmmio_fault_page *f) |
214 | { |
215 | int ret = clear_page_presence(f, clear: false); |
216 | WARN_ONCE(ret < 0, |
217 | KERN_ERR "kmmio disarming at 0x%08lx failed.\n" , f->addr); |
218 | f->armed = false; |
219 | } |
220 | |
221 | /* |
222 | * This is being called from do_page_fault(). |
223 | * |
224 | * We may be in an interrupt or a critical section. Also prefecthing may |
225 | * trigger a page fault. We may be in the middle of process switch. |
226 | * We cannot take any locks, because we could be executing especially |
227 | * within a kmmio critical section. |
228 | * |
229 | * Local interrupts are disabled, so preemption cannot happen. |
230 | * Do not enable interrupts, do not sleep, and watch out for other CPUs. |
231 | */ |
232 | /* |
233 | * Interrupts are disabled on entry as trap3 is an interrupt gate |
234 | * and they remain disabled throughout this function. |
235 | */ |
236 | int kmmio_handler(struct pt_regs *regs, unsigned long addr) |
237 | { |
238 | struct kmmio_context *ctx; |
239 | struct kmmio_fault_page *faultpage; |
240 | int ret = 0; /* default to fault not handled */ |
241 | unsigned long page_base = addr; |
242 | unsigned int l; |
243 | pte_t *pte = lookup_address(address: addr, level: &l); |
244 | if (!pte) |
245 | return -EINVAL; |
246 | page_base &= page_level_mask(level: l); |
247 | |
248 | /* |
249 | * Hold the RCU read lock over single stepping to avoid looking |
250 | * up the probe and kmmio_fault_page again. The rcu_read_lock_sched() |
251 | * also disables preemption and prevents process switch during |
252 | * the single stepping. We can only handle one active kmmio trace |
253 | * per cpu, so ensure that we finish it before something else |
254 | * gets to run. |
255 | */ |
256 | rcu_read_lock_sched_notrace(); |
257 | |
258 | faultpage = get_kmmio_fault_page(addr: page_base); |
259 | if (!faultpage) { |
260 | /* |
261 | * Either this page fault is not caused by kmmio, or |
262 | * another CPU just pulled the kmmio probe from under |
263 | * our feet. The latter case should not be possible. |
264 | */ |
265 | goto no_kmmio; |
266 | } |
267 | |
268 | ctx = this_cpu_ptr(&kmmio_ctx); |
269 | if (ctx->active) { |
270 | if (page_base == ctx->addr) { |
271 | /* |
272 | * A second fault on the same page means some other |
273 | * condition needs handling by do_page_fault(), the |
274 | * page really not being present is the most common. |
275 | */ |
276 | pr_debug("secondary hit for 0x%08lx CPU %d.\n" , |
277 | addr, smp_processor_id()); |
278 | |
279 | if (!faultpage->old_presence) |
280 | pr_info("unexpected secondary hit for address 0x%08lx on CPU %d.\n" , |
281 | addr, smp_processor_id()); |
282 | } else { |
283 | /* |
284 | * Prevent overwriting already in-flight context. |
285 | * This should not happen, let's hope disarming at |
286 | * least prevents a panic. |
287 | */ |
288 | pr_emerg("recursive probe hit on CPU %d, for address 0x%08lx. Ignoring.\n" , |
289 | smp_processor_id(), addr); |
290 | pr_emerg("previous hit was at 0x%08lx.\n" , ctx->addr); |
291 | disarm_kmmio_fault_page(f: faultpage); |
292 | } |
293 | goto no_kmmio; |
294 | } |
295 | ctx->active++; |
296 | |
297 | ctx->fpage = faultpage; |
298 | ctx->probe = get_kmmio_probe(addr: page_base); |
299 | ctx->saved_flags = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
300 | ctx->addr = page_base; |
301 | |
302 | if (ctx->probe && ctx->probe->pre_handler) |
303 | ctx->probe->pre_handler(ctx->probe, regs, addr); |
304 | |
305 | /* |
306 | * Enable single-stepping and disable interrupts for the faulting |
307 | * context. Local interrupts must not get enabled during stepping. |
308 | */ |
309 | regs->flags |= X86_EFLAGS_TF; |
310 | regs->flags &= ~X86_EFLAGS_IF; |
311 | |
312 | /* Now we set present bit in PTE and single step. */ |
313 | disarm_kmmio_fault_page(f: ctx->fpage); |
314 | |
315 | /* |
316 | * If another cpu accesses the same page while we are stepping, |
317 | * the access will not be caught. It will simply succeed and the |
318 | * only downside is we lose the event. If this becomes a problem, |
319 | * the user should drop to single cpu before tracing. |
320 | */ |
321 | |
322 | return 1; /* fault handled */ |
323 | |
324 | no_kmmio: |
325 | rcu_read_unlock_sched_notrace(); |
326 | return ret; |
327 | } |
328 | |
329 | /* |
330 | * Interrupts are disabled on entry as trap1 is an interrupt gate |
331 | * and they remain disabled throughout this function. |
332 | * This must always get called as the pair to kmmio_handler(). |
333 | */ |
334 | static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs) |
335 | { |
336 | int ret = 0; |
337 | struct kmmio_context *ctx = this_cpu_ptr(&kmmio_ctx); |
338 | |
339 | if (!ctx->active) { |
340 | /* |
341 | * debug traps without an active context are due to either |
342 | * something external causing them (f.e. using a debugger while |
343 | * mmio tracing enabled), or erroneous behaviour |
344 | */ |
345 | pr_warn("unexpected debug trap on CPU %d.\n" , smp_processor_id()); |
346 | goto out; |
347 | } |
348 | |
349 | if (ctx->probe && ctx->probe->post_handler) |
350 | ctx->probe->post_handler(ctx->probe, condition, regs); |
351 | |
352 | /* Prevent racing against release_kmmio_fault_page(). */ |
353 | arch_spin_lock(&kmmio_lock); |
354 | if (ctx->fpage->count) |
355 | arm_kmmio_fault_page(f: ctx->fpage); |
356 | arch_spin_unlock(&kmmio_lock); |
357 | |
358 | regs->flags &= ~X86_EFLAGS_TF; |
359 | regs->flags |= ctx->saved_flags; |
360 | |
361 | /* These were acquired in kmmio_handler(). */ |
362 | ctx->active--; |
363 | BUG_ON(ctx->active); |
364 | rcu_read_unlock_sched_notrace(); |
365 | |
366 | /* |
367 | * if somebody else is singlestepping across a probe point, flags |
368 | * will have TF set, in which case, continue the remaining processing |
369 | * of do_debug, as if this is not a probe hit. |
370 | */ |
371 | if (!(regs->flags & X86_EFLAGS_TF)) |
372 | ret = 1; |
373 | out: |
374 | return ret; |
375 | } |
376 | |
377 | /* You must be holding kmmio_lock. */ |
378 | static int add_kmmio_fault_page(unsigned long addr) |
379 | { |
380 | struct kmmio_fault_page *f; |
381 | |
382 | f = get_kmmio_fault_page(addr); |
383 | if (f) { |
384 | if (!f->count) |
385 | arm_kmmio_fault_page(f); |
386 | f->count++; |
387 | return 0; |
388 | } |
389 | |
390 | f = kzalloc(size: sizeof(*f), GFP_ATOMIC); |
391 | if (!f) |
392 | return -1; |
393 | |
394 | f->count = 1; |
395 | f->addr = addr; |
396 | |
397 | if (arm_kmmio_fault_page(f)) { |
398 | kfree(objp: f); |
399 | return -1; |
400 | } |
401 | |
402 | list_add_rcu(new: &f->list, head: kmmio_page_list(addr: f->addr)); |
403 | |
404 | return 0; |
405 | } |
406 | |
407 | /* You must be holding kmmio_lock. */ |
408 | static void release_kmmio_fault_page(unsigned long addr, |
409 | struct kmmio_fault_page **release_list) |
410 | { |
411 | struct kmmio_fault_page *f; |
412 | |
413 | f = get_kmmio_fault_page(addr); |
414 | if (!f) |
415 | return; |
416 | |
417 | f->count--; |
418 | BUG_ON(f->count < 0); |
419 | if (!f->count) { |
420 | disarm_kmmio_fault_page(f); |
421 | if (!f->scheduled_for_release) { |
422 | f->release_next = *release_list; |
423 | *release_list = f; |
424 | f->scheduled_for_release = true; |
425 | } |
426 | } |
427 | } |
428 | |
429 | /* |
430 | * With page-unaligned ioremaps, one or two armed pages may contain |
431 | * addresses from outside the intended mapping. Events for these addresses |
432 | * are currently silently dropped. The events may result only from programming |
433 | * mistakes by accessing addresses before the beginning or past the end of a |
434 | * mapping. |
435 | */ |
436 | int register_kmmio_probe(struct kmmio_probe *p) |
437 | { |
438 | unsigned long flags; |
439 | int ret = 0; |
440 | unsigned long size = 0; |
441 | unsigned long addr = p->addr & PAGE_MASK; |
442 | const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); |
443 | unsigned int l; |
444 | pte_t *pte; |
445 | |
446 | local_irq_save(flags); |
447 | arch_spin_lock(&kmmio_lock); |
448 | if (get_kmmio_probe(addr)) { |
449 | ret = -EEXIST; |
450 | goto out; |
451 | } |
452 | |
453 | pte = lookup_address(address: addr, level: &l); |
454 | if (!pte) { |
455 | ret = -EINVAL; |
456 | goto out; |
457 | } |
458 | |
459 | kmmio_count++; |
460 | list_add_rcu(new: &p->list, head: &kmmio_probes); |
461 | while (size < size_lim) { |
462 | if (add_kmmio_fault_page(addr: addr + size)) |
463 | pr_err("Unable to set page fault.\n" ); |
464 | size += page_level_size(level: l); |
465 | } |
466 | out: |
467 | arch_spin_unlock(&kmmio_lock); |
468 | local_irq_restore(flags); |
469 | |
470 | /* |
471 | * XXX: What should I do here? |
472 | * Here was a call to global_flush_tlb(), but it does not exist |
473 | * anymore. It seems it's not needed after all. |
474 | */ |
475 | return ret; |
476 | } |
477 | EXPORT_SYMBOL(register_kmmio_probe); |
478 | |
479 | static void rcu_free_kmmio_fault_pages(struct rcu_head *head) |
480 | { |
481 | struct kmmio_delayed_release *dr = container_of( |
482 | head, |
483 | struct kmmio_delayed_release, |
484 | rcu); |
485 | struct kmmio_fault_page *f = dr->release_list; |
486 | while (f) { |
487 | struct kmmio_fault_page *next = f->release_next; |
488 | BUG_ON(f->count); |
489 | kfree(objp: f); |
490 | f = next; |
491 | } |
492 | kfree(objp: dr); |
493 | } |
494 | |
495 | static void remove_kmmio_fault_pages(struct rcu_head *head) |
496 | { |
497 | struct kmmio_delayed_release *dr = |
498 | container_of(head, struct kmmio_delayed_release, rcu); |
499 | struct kmmio_fault_page *f = dr->release_list; |
500 | struct kmmio_fault_page **prevp = &dr->release_list; |
501 | unsigned long flags; |
502 | |
503 | local_irq_save(flags); |
504 | arch_spin_lock(&kmmio_lock); |
505 | while (f) { |
506 | if (!f->count) { |
507 | list_del_rcu(entry: &f->list); |
508 | prevp = &f->release_next; |
509 | } else { |
510 | *prevp = f->release_next; |
511 | f->release_next = NULL; |
512 | f->scheduled_for_release = false; |
513 | } |
514 | f = *prevp; |
515 | } |
516 | arch_spin_unlock(&kmmio_lock); |
517 | local_irq_restore(flags); |
518 | |
519 | /* This is the real RCU destroy call. */ |
520 | call_rcu(head: &dr->rcu, func: rcu_free_kmmio_fault_pages); |
521 | } |
522 | |
523 | /* |
524 | * Remove a kmmio probe. You have to synchronize_rcu() before you can be |
525 | * sure that the callbacks will not be called anymore. Only after that |
526 | * you may actually release your struct kmmio_probe. |
527 | * |
528 | * Unregistering a kmmio fault page has three steps: |
529 | * 1. release_kmmio_fault_page() |
530 | * Disarm the page, wait a grace period to let all faults finish. |
531 | * 2. remove_kmmio_fault_pages() |
532 | * Remove the pages from kmmio_page_table. |
533 | * 3. rcu_free_kmmio_fault_pages() |
534 | * Actually free the kmmio_fault_page structs as with RCU. |
535 | */ |
536 | void unregister_kmmio_probe(struct kmmio_probe *p) |
537 | { |
538 | unsigned long flags; |
539 | unsigned long size = 0; |
540 | unsigned long addr = p->addr & PAGE_MASK; |
541 | const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); |
542 | struct kmmio_fault_page *release_list = NULL; |
543 | struct kmmio_delayed_release *drelease; |
544 | unsigned int l; |
545 | pte_t *pte; |
546 | |
547 | pte = lookup_address(address: addr, level: &l); |
548 | if (!pte) |
549 | return; |
550 | |
551 | local_irq_save(flags); |
552 | arch_spin_lock(&kmmio_lock); |
553 | while (size < size_lim) { |
554 | release_kmmio_fault_page(addr: addr + size, release_list: &release_list); |
555 | size += page_level_size(level: l); |
556 | } |
557 | list_del_rcu(entry: &p->list); |
558 | kmmio_count--; |
559 | arch_spin_unlock(&kmmio_lock); |
560 | local_irq_restore(flags); |
561 | |
562 | if (!release_list) |
563 | return; |
564 | |
565 | drelease = kmalloc(size: sizeof(*drelease), GFP_ATOMIC); |
566 | if (!drelease) { |
567 | pr_crit("leaking kmmio_fault_page objects.\n" ); |
568 | return; |
569 | } |
570 | drelease->release_list = release_list; |
571 | |
572 | /* |
573 | * This is not really RCU here. We have just disarmed a set of |
574 | * pages so that they cannot trigger page faults anymore. However, |
575 | * we cannot remove the pages from kmmio_page_table, |
576 | * because a probe hit might be in flight on another CPU. The |
577 | * pages are collected into a list, and they will be removed from |
578 | * kmmio_page_table when it is certain that no probe hit related to |
579 | * these pages can be in flight. RCU grace period sounds like a |
580 | * good choice. |
581 | * |
582 | * If we removed the pages too early, kmmio page fault handler might |
583 | * not find the respective kmmio_fault_page and determine it's not |
584 | * a kmmio fault, when it actually is. This would lead to madness. |
585 | */ |
586 | call_rcu(head: &drelease->rcu, func: remove_kmmio_fault_pages); |
587 | } |
588 | EXPORT_SYMBOL(unregister_kmmio_probe); |
589 | |
590 | static int |
591 | kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args) |
592 | { |
593 | struct die_args *arg = args; |
594 | unsigned long* dr6_p = (unsigned long *)ERR_PTR(error: arg->err); |
595 | |
596 | if (val == DIE_DEBUG && (*dr6_p & DR_STEP)) |
597 | if (post_kmmio_handler(condition: *dr6_p, regs: arg->regs) == 1) { |
598 | /* |
599 | * Reset the BS bit in dr6 (pointed by args->err) to |
600 | * denote completion of processing |
601 | */ |
602 | *dr6_p &= ~DR_STEP; |
603 | return NOTIFY_STOP; |
604 | } |
605 | |
606 | return NOTIFY_DONE; |
607 | } |
608 | |
609 | static struct notifier_block nb_die = { |
610 | .notifier_call = kmmio_die_notifier |
611 | }; |
612 | |
613 | int kmmio_init(void) |
614 | { |
615 | int i; |
616 | |
617 | for (i = 0; i < KMMIO_PAGE_TABLE_SIZE; i++) |
618 | INIT_LIST_HEAD(list: &kmmio_page_table[i]); |
619 | |
620 | return register_die_notifier(nb: &nb_die); |
621 | } |
622 | |
623 | void kmmio_cleanup(void) |
624 | { |
625 | int i; |
626 | |
627 | unregister_die_notifier(nb: &nb_die); |
628 | for (i = 0; i < KMMIO_PAGE_TABLE_SIZE; i++) { |
629 | WARN_ONCE(!list_empty(&kmmio_page_table[i]), |
630 | KERN_ERR "kmmio_page_table not empty at cleanup, any further tracing will leak memory.\n" ); |
631 | } |
632 | } |
633 | |