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Don Zickus1d489222011-09-30 15:06:19 -04001/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
Don Zickus9c48f1c2011-09-30 15:06:21 -04004 * Copyright (C) 2011 Don Zickus Red Hat, Inc.
Don Zickus1d489222011-09-30 15:06:19 -04005 *
6 * Pentium III FXSR, SSE support
7 * Gareth Hughes <gareth@valinux.com>, May 2000
8 */
9
10/*
11 * Handle hardware traps and faults.
12 */
13#include <linux/spinlock.h>
14#include <linux/kprobes.h>
15#include <linux/kdebug.h>
16#include <linux/nmi.h>
Don Zickusc9126b22011-09-30 15:06:20 -040017#include <linux/delay.h>
18#include <linux/hardirq.h>
19#include <linux/slab.h>
Paul Gortmaker69c60c82011-05-26 12:22:53 -040020#include <linux/export.h>
Don Zickus1d489222011-09-30 15:06:19 -040021
22#if defined(CONFIG_EDAC)
23#include <linux/edac.h>
24#endif
25
26#include <linux/atomic.h>
27#include <asm/traps.h>
28#include <asm/mach_traps.h>
Don Zickusc9126b22011-09-30 15:06:20 -040029#include <asm/nmi.h>
Mathias Nyman6fd36ba2011-11-10 13:45:24 +000030#include <asm/x86_init.h>
Don Zickusc9126b22011-09-30 15:06:20 -040031
Don Zickusc9126b22011-09-30 15:06:20 -040032struct nmi_desc {
33 spinlock_t lock;
34 struct list_head head;
35};
36
37static struct nmi_desc nmi_desc[NMI_MAX] =
38{
39 {
40 .lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[0].lock),
41 .head = LIST_HEAD_INIT(nmi_desc[0].head),
42 },
43 {
44 .lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[1].lock),
45 .head = LIST_HEAD_INIT(nmi_desc[1].head),
46 },
Don Zickus553222f2012-03-29 16:11:16 -040047 {
48 .lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[2].lock),
49 .head = LIST_HEAD_INIT(nmi_desc[2].head),
50 },
51 {
52 .lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[3].lock),
53 .head = LIST_HEAD_INIT(nmi_desc[3].head),
54 },
Don Zickusc9126b22011-09-30 15:06:20 -040055
56};
Don Zickus1d489222011-09-30 15:06:19 -040057
Don Zickusefc3aac2011-09-30 15:06:23 -040058struct nmi_stats {
59 unsigned int normal;
60 unsigned int unknown;
61 unsigned int external;
62 unsigned int swallow;
63};
64
65static DEFINE_PER_CPU(struct nmi_stats, nmi_stats);
66
Don Zickus1d489222011-09-30 15:06:19 -040067static int ignore_nmis;
68
69int unknown_nmi_panic;
70/*
71 * Prevent NMI reason port (0x61) being accessed simultaneously, can
72 * only be used in NMI handler.
73 */
74static DEFINE_RAW_SPINLOCK(nmi_reason_lock);
75
76static int __init setup_unknown_nmi_panic(char *str)
77{
78 unknown_nmi_panic = 1;
79 return 1;
80}
81__setup("unknown_nmi_panic", setup_unknown_nmi_panic);
82
Don Zickusc9126b22011-09-30 15:06:20 -040083#define nmi_to_desc(type) (&nmi_desc[type])
84
Steven Rostedt4a6d70c2012-04-24 16:31:07 -040085static int __kprobes nmi_handle(unsigned int type, struct pt_regs *regs, bool b2b)
Don Zickusc9126b22011-09-30 15:06:20 -040086{
87 struct nmi_desc *desc = nmi_to_desc(type);
88 struct nmiaction *a;
89 int handled=0;
90
91 rcu_read_lock();
92
93 /*
94 * NMIs are edge-triggered, which means if you have enough
95 * of them concurrently, you can lose some because only one
96 * can be latched at any given time. Walk the whole list
97 * to handle those situations.
98 */
Don Zickusb227e232011-09-30 15:06:22 -040099 list_for_each_entry_rcu(a, &desc->head, list)
Don Zickusc9126b22011-09-30 15:06:20 -0400100 handled += a->handler(type, regs);
101
Don Zickusc9126b22011-09-30 15:06:20 -0400102 rcu_read_unlock();
103
104 /* return total number of NMI events handled */
105 return handled;
106}
107
Li Zhong72b3fb22012-03-29 16:11:17 -0400108int __register_nmi_handler(unsigned int type, struct nmiaction *action)
Don Zickusc9126b22011-09-30 15:06:20 -0400109{
110 struct nmi_desc *desc = nmi_to_desc(type);
111 unsigned long flags;
112
Li Zhong72b3fb22012-03-29 16:11:17 -0400113 if (!action->handler)
114 return -EINVAL;
115
Don Zickusc9126b22011-09-30 15:06:20 -0400116 spin_lock_irqsave(&desc->lock, flags);
117
118 /*
Don Zickusb227e232011-09-30 15:06:22 -0400119 * most handlers of type NMI_UNKNOWN never return because
120 * they just assume the NMI is theirs. Just a sanity check
121 * to manage expectations
122 */
123 WARN_ON_ONCE(type == NMI_UNKNOWN && !list_empty(&desc->head));
Don Zickus553222f2012-03-29 16:11:16 -0400124 WARN_ON_ONCE(type == NMI_SERR && !list_empty(&desc->head));
125 WARN_ON_ONCE(type == NMI_IO_CHECK && !list_empty(&desc->head));
Don Zickusb227e232011-09-30 15:06:22 -0400126
127 /*
Don Zickusc9126b22011-09-30 15:06:20 -0400128 * some handlers need to be executed first otherwise a fake
129 * event confuses some handlers (kdump uses this flag)
130 */
131 if (action->flags & NMI_FLAG_FIRST)
132 list_add_rcu(&action->list, &desc->head);
133 else
134 list_add_tail_rcu(&action->list, &desc->head);
135
136 spin_unlock_irqrestore(&desc->lock, flags);
137 return 0;
138}
Li Zhong72b3fb22012-03-29 16:11:17 -0400139EXPORT_SYMBOL(__register_nmi_handler);
Don Zickusc9126b22011-09-30 15:06:20 -0400140
Li Zhong72b3fb22012-03-29 16:11:17 -0400141void unregister_nmi_handler(unsigned int type, const char *name)
Don Zickusc9126b22011-09-30 15:06:20 -0400142{
143 struct nmi_desc *desc = nmi_to_desc(type);
144 struct nmiaction *n;
145 unsigned long flags;
146
147 spin_lock_irqsave(&desc->lock, flags);
148
149 list_for_each_entry_rcu(n, &desc->head, list) {
150 /*
151 * the name passed in to describe the nmi handler
152 * is used as the lookup key
153 */
154 if (!strcmp(n->name, name)) {
155 WARN(in_nmi(),
156 "Trying to free NMI (%s) from NMI context!\n", n->name);
157 list_del_rcu(&n->list);
158 break;
159 }
160 }
161
162 spin_unlock_irqrestore(&desc->lock, flags);
163 synchronize_rcu();
Don Zickusc9126b22011-09-30 15:06:20 -0400164}
Don Zickusc9126b22011-09-30 15:06:20 -0400165EXPORT_SYMBOL_GPL(unregister_nmi_handler);
166
Steven Rostedt4a6d70c2012-04-24 16:31:07 -0400167static __kprobes void
Don Zickus1d489222011-09-30 15:06:19 -0400168pci_serr_error(unsigned char reason, struct pt_regs *regs)
169{
Don Zickus553222f2012-03-29 16:11:16 -0400170 /* check to see if anyone registered against these types of errors */
171 if (nmi_handle(NMI_SERR, regs, false))
172 return;
173
Don Zickus1d489222011-09-30 15:06:19 -0400174 pr_emerg("NMI: PCI system error (SERR) for reason %02x on CPU %d.\n",
175 reason, smp_processor_id());
176
177 /*
178 * On some machines, PCI SERR line is used to report memory
179 * errors. EDAC makes use of it.
180 */
181#if defined(CONFIG_EDAC)
182 if (edac_handler_set()) {
183 edac_atomic_assert_error();
184 return;
185 }
186#endif
187
188 if (panic_on_unrecovered_nmi)
189 panic("NMI: Not continuing");
190
191 pr_emerg("Dazed and confused, but trying to continue\n");
192
193 /* Clear and disable the PCI SERR error line. */
194 reason = (reason & NMI_REASON_CLEAR_MASK) | NMI_REASON_CLEAR_SERR;
195 outb(reason, NMI_REASON_PORT);
196}
197
Steven Rostedt4a6d70c2012-04-24 16:31:07 -0400198static __kprobes void
Don Zickus1d489222011-09-30 15:06:19 -0400199io_check_error(unsigned char reason, struct pt_regs *regs)
200{
201 unsigned long i;
202
Don Zickus553222f2012-03-29 16:11:16 -0400203 /* check to see if anyone registered against these types of errors */
204 if (nmi_handle(NMI_IO_CHECK, regs, false))
205 return;
206
Don Zickus1d489222011-09-30 15:06:19 -0400207 pr_emerg(
208 "NMI: IOCK error (debug interrupt?) for reason %02x on CPU %d.\n",
209 reason, smp_processor_id());
Jan Beulich57da8b92012-05-09 08:47:37 +0100210 show_regs(regs);
Don Zickus1d489222011-09-30 15:06:19 -0400211
212 if (panic_on_io_nmi)
213 panic("NMI IOCK error: Not continuing");
214
215 /* Re-enable the IOCK line, wait for a few seconds */
216 reason = (reason & NMI_REASON_CLEAR_MASK) | NMI_REASON_CLEAR_IOCHK;
217 outb(reason, NMI_REASON_PORT);
218
219 i = 20000;
220 while (--i) {
221 touch_nmi_watchdog();
222 udelay(100);
223 }
224
225 reason &= ~NMI_REASON_CLEAR_IOCHK;
226 outb(reason, NMI_REASON_PORT);
227}
228
Steven Rostedt4a6d70c2012-04-24 16:31:07 -0400229static __kprobes void
Don Zickus1d489222011-09-30 15:06:19 -0400230unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
231{
Don Zickus9c48f1c2011-09-30 15:06:21 -0400232 int handled;
233
Don Zickusb227e232011-09-30 15:06:22 -0400234 /*
235 * Use 'false' as back-to-back NMIs are dealt with one level up.
236 * Of course this makes having multiple 'unknown' handlers useless
237 * as only the first one is ever run (unless it can actually determine
238 * if it caused the NMI)
239 */
240 handled = nmi_handle(NMI_UNKNOWN, regs, false);
Don Zickusefc3aac2011-09-30 15:06:23 -0400241 if (handled) {
242 __this_cpu_add(nmi_stats.unknown, handled);
Don Zickus1d489222011-09-30 15:06:19 -0400243 return;
Don Zickusefc3aac2011-09-30 15:06:23 -0400244 }
245
246 __this_cpu_add(nmi_stats.unknown, 1);
247
Don Zickus1d489222011-09-30 15:06:19 -0400248 pr_emerg("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
249 reason, smp_processor_id());
250
251 pr_emerg("Do you have a strange power saving mode enabled?\n");
252 if (unknown_nmi_panic || panic_on_unrecovered_nmi)
253 panic("NMI: Not continuing");
254
255 pr_emerg("Dazed and confused, but trying to continue\n");
256}
257
Don Zickusb227e232011-09-30 15:06:22 -0400258static DEFINE_PER_CPU(bool, swallow_nmi);
259static DEFINE_PER_CPU(unsigned long, last_nmi_rip);
260
Steven Rostedt4a6d70c2012-04-24 16:31:07 -0400261static __kprobes void default_do_nmi(struct pt_regs *regs)
Don Zickus1d489222011-09-30 15:06:19 -0400262{
263 unsigned char reason = 0;
Don Zickus9c48f1c2011-09-30 15:06:21 -0400264 int handled;
Don Zickusb227e232011-09-30 15:06:22 -0400265 bool b2b = false;
Don Zickus1d489222011-09-30 15:06:19 -0400266
267 /*
268 * CPU-specific NMI must be processed before non-CPU-specific
269 * NMI, otherwise we may lose it, because the CPU-specific
270 * NMI can not be detected/processed on other CPUs.
271 */
Don Zickusb227e232011-09-30 15:06:22 -0400272
273 /*
274 * Back-to-back NMIs are interesting because they can either
275 * be two NMI or more than two NMIs (any thing over two is dropped
276 * due to NMI being edge-triggered). If this is the second half
277 * of the back-to-back NMI, assume we dropped things and process
278 * more handlers. Otherwise reset the 'swallow' NMI behaviour
279 */
280 if (regs->ip == __this_cpu_read(last_nmi_rip))
281 b2b = true;
282 else
283 __this_cpu_write(swallow_nmi, false);
284
285 __this_cpu_write(last_nmi_rip, regs->ip);
286
287 handled = nmi_handle(NMI_LOCAL, regs, b2b);
Don Zickusefc3aac2011-09-30 15:06:23 -0400288 __this_cpu_add(nmi_stats.normal, handled);
Don Zickusb227e232011-09-30 15:06:22 -0400289 if (handled) {
290 /*
291 * There are cases when a NMI handler handles multiple
292 * events in the current NMI. One of these events may
293 * be queued for in the next NMI. Because the event is
294 * already handled, the next NMI will result in an unknown
295 * NMI. Instead lets flag this for a potential NMI to
296 * swallow.
297 */
298 if (handled > 1)
299 __this_cpu_write(swallow_nmi, true);
Don Zickus1d489222011-09-30 15:06:19 -0400300 return;
Don Zickusb227e232011-09-30 15:06:22 -0400301 }
Don Zickus1d489222011-09-30 15:06:19 -0400302
303 /* Non-CPU-specific NMI: NMI sources can be processed on any CPU */
304 raw_spin_lock(&nmi_reason_lock);
Jacob Pan064a59b2011-11-10 13:43:05 +0000305 reason = x86_platform.get_nmi_reason();
Don Zickus1d489222011-09-30 15:06:19 -0400306
307 if (reason & NMI_REASON_MASK) {
308 if (reason & NMI_REASON_SERR)
309 pci_serr_error(reason, regs);
310 else if (reason & NMI_REASON_IOCHK)
311 io_check_error(reason, regs);
312#ifdef CONFIG_X86_32
313 /*
314 * Reassert NMI in case it became active
315 * meanwhile as it's edge-triggered:
316 */
317 reassert_nmi();
318#endif
Don Zickusefc3aac2011-09-30 15:06:23 -0400319 __this_cpu_add(nmi_stats.external, 1);
Don Zickus1d489222011-09-30 15:06:19 -0400320 raw_spin_unlock(&nmi_reason_lock);
321 return;
322 }
323 raw_spin_unlock(&nmi_reason_lock);
324
Don Zickusb227e232011-09-30 15:06:22 -0400325 /*
326 * Only one NMI can be latched at a time. To handle
327 * this we may process multiple nmi handlers at once to
328 * cover the case where an NMI is dropped. The downside
329 * to this approach is we may process an NMI prematurely,
330 * while its real NMI is sitting latched. This will cause
331 * an unknown NMI on the next run of the NMI processing.
332 *
333 * We tried to flag that condition above, by setting the
334 * swallow_nmi flag when we process more than one event.
335 * This condition is also only present on the second half
336 * of a back-to-back NMI, so we flag that condition too.
337 *
338 * If both are true, we assume we already processed this
339 * NMI previously and we swallow it. Otherwise we reset
340 * the logic.
341 *
342 * There are scenarios where we may accidentally swallow
343 * a 'real' unknown NMI. For example, while processing
344 * a perf NMI another perf NMI comes in along with a
345 * 'real' unknown NMI. These two NMIs get combined into
346 * one (as descibed above). When the next NMI gets
347 * processed, it will be flagged by perf as handled, but
348 * noone will know that there was a 'real' unknown NMI sent
349 * also. As a result it gets swallowed. Or if the first
350 * perf NMI returns two events handled then the second
351 * NMI will get eaten by the logic below, again losing a
352 * 'real' unknown NMI. But this is the best we can do
353 * for now.
354 */
355 if (b2b && __this_cpu_read(swallow_nmi))
Don Zickusefc3aac2011-09-30 15:06:23 -0400356 __this_cpu_add(nmi_stats.swallow, 1);
Don Zickusb227e232011-09-30 15:06:22 -0400357 else
358 unknown_nmi_error(reason, regs);
Don Zickus1d489222011-09-30 15:06:19 -0400359}
360
Steven Rostedtccd49c22011-12-13 16:44:16 -0500361/*
362 * NMIs can hit breakpoints which will cause it to lose its
363 * NMI context with the CPU when the breakpoint does an iret.
364 */
365#ifdef CONFIG_X86_32
366/*
367 * For i386, NMIs use the same stack as the kernel, and we can
Steven Rostedtc7d65a72012-06-07 11:03:00 -0400368 * add a workaround to the iret problem in C (preventing nested
369 * NMIs if an NMI takes a trap). Simply have 3 states the NMI
370 * can be in:
Steven Rostedtccd49c22011-12-13 16:44:16 -0500371 *
372 * 1) not running
373 * 2) executing
374 * 3) latched
375 *
376 * When no NMI is in progress, it is in the "not running" state.
377 * When an NMI comes in, it goes into the "executing" state.
378 * Normally, if another NMI is triggered, it does not interrupt
379 * the running NMI and the HW will simply latch it so that when
380 * the first NMI finishes, it will restart the second NMI.
381 * (Note, the latch is binary, thus multiple NMIs triggering,
382 * when one is running, are ignored. Only one NMI is restarted.)
383 *
384 * If an NMI hits a breakpoint that executes an iret, another
385 * NMI can preempt it. We do not want to allow this new NMI
386 * to run, but we want to execute it when the first one finishes.
Steven Rostedtc7d65a72012-06-07 11:03:00 -0400387 * We set the state to "latched", and the exit of the first NMI will
388 * perform a dec_return, if the result is zero (NOT_RUNNING), then
389 * it will simply exit the NMI handler. If not, the dec_return
390 * would have set the state to NMI_EXECUTING (what we want it to
391 * be when we are running). In this case, we simply jump back
392 * to rerun the NMI handler again, and restart the 'latched' NMI.
393 *
394 * No trap (breakpoint or page fault) should be hit before nmi_restart,
395 * thus there is no race between the first check of state for NOT_RUNNING
396 * and setting it to NMI_EXECUTING. The HW will prevent nested NMIs
397 * at this point.
Steven Rostedt70fb74a2012-06-07 11:54:37 -0400398 *
399 * In case the NMI takes a page fault, we need to save off the CR2
400 * because the NMI could have preempted another page fault and corrupt
401 * the CR2 that is about to be read. As nested NMIs must be restarted
402 * and they can not take breakpoints or page faults, the update of the
403 * CR2 must be done before converting the nmi state back to NOT_RUNNING.
404 * Otherwise, there would be a race of another nested NMI coming in
405 * after setting state to NOT_RUNNING but before updating the nmi_cr2.
Steven Rostedtccd49c22011-12-13 16:44:16 -0500406 */
407enum nmi_states {
Steven Rostedtc7d65a72012-06-07 11:03:00 -0400408 NMI_NOT_RUNNING = 0,
Steven Rostedtccd49c22011-12-13 16:44:16 -0500409 NMI_EXECUTING,
410 NMI_LATCHED,
411};
412static DEFINE_PER_CPU(enum nmi_states, nmi_state);
Steven Rostedt70fb74a2012-06-07 11:54:37 -0400413static DEFINE_PER_CPU(unsigned long, nmi_cr2);
Steven Rostedt228bdaa2011-12-09 03:02:19 -0500414
Steven Rostedtccd49c22011-12-13 16:44:16 -0500415#define nmi_nesting_preprocess(regs) \
416 do { \
Steven Rostedtc7d65a72012-06-07 11:03:00 -0400417 if (this_cpu_read(nmi_state) != NMI_NOT_RUNNING) { \
418 this_cpu_write(nmi_state, NMI_LATCHED); \
Steven Rostedtccd49c22011-12-13 16:44:16 -0500419 return; \
420 } \
Steven Rostedtc7d65a72012-06-07 11:03:00 -0400421 this_cpu_write(nmi_state, NMI_EXECUTING); \
Steven Rostedt70fb74a2012-06-07 11:54:37 -0400422 this_cpu_write(nmi_cr2, read_cr2()); \
Steven Rostedtc7d65a72012-06-07 11:03:00 -0400423 } while (0); \
424 nmi_restart:
Steven Rostedtccd49c22011-12-13 16:44:16 -0500425
426#define nmi_nesting_postprocess() \
427 do { \
Steven Rostedt70fb74a2012-06-07 11:54:37 -0400428 if (unlikely(this_cpu_read(nmi_cr2) != read_cr2())) \
429 write_cr2(this_cpu_read(nmi_cr2)); \
Steven Rostedtc7d65a72012-06-07 11:03:00 -0400430 if (this_cpu_dec_return(nmi_state)) \
Steven Rostedtccd49c22011-12-13 16:44:16 -0500431 goto nmi_restart; \
432 } while (0)
433#else /* x86_64 */
434/*
435 * In x86_64 things are a bit more difficult. This has the same problem
436 * where an NMI hitting a breakpoint that calls iret will remove the
437 * NMI context, allowing a nested NMI to enter. What makes this more
438 * difficult is that both NMIs and breakpoints have their own stack.
439 * When a new NMI or breakpoint is executed, the stack is set to a fixed
440 * point. If an NMI is nested, it will have its stack set at that same
441 * fixed address that the first NMI had, and will start corrupting the
442 * stack. This is handled in entry_64.S, but the same problem exists with
443 * the breakpoint stack.
444 *
445 * If a breakpoint is being processed, and the debug stack is being used,
446 * if an NMI comes in and also hits a breakpoint, the stack pointer
447 * will be set to the same fixed address as the breakpoint that was
448 * interrupted, causing that stack to be corrupted. To handle this case,
449 * check if the stack that was interrupted is the debug stack, and if
450 * so, change the IDT so that new breakpoints will use the current stack
451 * and not switch to the fixed address. On return of the NMI, switch back
452 * to the original IDT.
453 */
454static DEFINE_PER_CPU(int, update_debug_stack);
455
456static inline void nmi_nesting_preprocess(struct pt_regs *regs)
457{
Steven Rostedt228bdaa2011-12-09 03:02:19 -0500458 /*
459 * If we interrupted a breakpoint, it is possible that
460 * the nmi handler will have breakpoints too. We need to
461 * change the IDT such that breakpoints that happen here
462 * continue to use the NMI stack.
463 */
464 if (unlikely(is_debug_stack(regs->sp))) {
465 debug_stack_set_zero();
Steven Rostedtc0525a62012-05-30 11:43:19 -0400466 this_cpu_write(update_debug_stack, 1);
Steven Rostedt228bdaa2011-12-09 03:02:19 -0500467 }
Steven Rostedtccd49c22011-12-13 16:44:16 -0500468}
469
470static inline void nmi_nesting_postprocess(void)
471{
Steven Rostedtc0525a62012-05-30 11:43:19 -0400472 if (unlikely(this_cpu_read(update_debug_stack))) {
Steven Rostedtccd49c22011-12-13 16:44:16 -0500473 debug_stack_reset();
Steven Rostedtc0525a62012-05-30 11:43:19 -0400474 this_cpu_write(update_debug_stack, 0);
475 }
Steven Rostedtccd49c22011-12-13 16:44:16 -0500476}
477#endif
478
479dotraplinkage notrace __kprobes void
480do_nmi(struct pt_regs *regs, long error_code)
481{
482 nmi_nesting_preprocess(regs);
483
Don Zickus1d489222011-09-30 15:06:19 -0400484 nmi_enter();
485
486 inc_irq_stat(__nmi_count);
487
488 if (!ignore_nmis)
489 default_do_nmi(regs);
490
491 nmi_exit();
Steven Rostedt228bdaa2011-12-09 03:02:19 -0500492
Steven Rostedtccd49c22011-12-13 16:44:16 -0500493 /* On i386, may loop back to preprocess */
494 nmi_nesting_postprocess();
Don Zickus1d489222011-09-30 15:06:19 -0400495}
496
497void stop_nmi(void)
498{
499 ignore_nmis++;
500}
501
502void restart_nmi(void)
503{
504 ignore_nmis--;
505}
Don Zickusb227e232011-09-30 15:06:22 -0400506
507/* reset the back-to-back NMI logic */
508void local_touch_nmi(void)
509{
510 __this_cpu_write(last_nmi_rip, 0);
511}