1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Derived from arch/i386/kernel/irq.c
4 * Copyright (C) 1992 Linus Torvalds
5 * Adapted from arch/i386 by Gary Thomas
6 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
7 * Updated and modified by Cort Dougan <cort@fsmlabs.com>
8 * Copyright (C) 1996-2001 Cort Dougan
9 * Adapted for Power Macintosh by Paul Mackerras
10 * Copyright (C) 1996 Paul Mackerras (paulus@cs.anu.edu.au)
11 *
12 * This file contains the code used by various IRQ handling routines:
13 * asking for different IRQ's should be done through these routines
14 * instead of just grabbing them. Thus setups with different IRQ numbers
15 * shouldn't result in any weird surprises, and installing new handlers
16 * should be easier.
17 */
18
19 #undef DEBUG
20
21 #include <linux/export.h>
22 #include <linux/threads.h>
23 #include <linux/kernel_stat.h>
24 #include <linux/signal.h>
25 #include <linux/sched.h>
26 #include <linux/ptrace.h>
27 #include <linux/ioport.h>
28 #include <linux/interrupt.h>
29 #include <linux/timex.h>
30 #include <linux/init.h>
31 #include <linux/slab.h>
32 #include <linux/delay.h>
33 #include <linux/irq.h>
34 #include <linux/seq_file.h>
35 #include <linux/cpumask.h>
36 #include <linux/profile.h>
37 #include <linux/bitops.h>
38 #include <linux/list.h>
39 #include <linux/radix-tree.h>
40 #include <linux/mutex.h>
41 #include <linux/pci.h>
42 #include <linux/debugfs.h>
43 #include <linux/of.h>
44 #include <linux/of_irq.h>
45 #include <linux/vmalloc.h>
46 #include <linux/pgtable.h>
47 #include <linux/static_call.h>
48
49 #include <linux/uaccess.h>
50 #include <asm/interrupt.h>
51 #include <asm/io.h>
52 #include <asm/irq.h>
53 #include <asm/cache.h>
54 #include <asm/ptrace.h>
55 #include <asm/machdep.h>
56 #include <asm/udbg.h>
57 #include <asm/smp.h>
58 #include <asm/hw_irq.h>
59 #include <asm/softirq_stack.h>
60 #include <asm/ppc_asm.h>
61
62 #include <asm/paca.h>
63 #include <asm/firmware.h>
64 #include <asm/lv1call.h>
65 #include <asm/dbell.h>
66 #include <asm/trace.h>
67 #include <asm/cpu_has_feature.h>
68
69 int distribute_irqs = 1;
70
next_interrupt(struct pt_regs * regs)71 static inline void next_interrupt(struct pt_regs *regs)
72 {
73 if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
74 WARN_ON(!(local_paca->irq_happened & PACA_IRQ_HARD_DIS));
75 WARN_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED);
76 }
77
78 /*
79 * We are responding to the next interrupt, so interrupt-off
80 * latencies should be reset here.
81 */
82 lockdep_hardirq_exit();
83 trace_hardirqs_on();
84 trace_hardirqs_off();
85 lockdep_hardirq_enter();
86 }
87
irq_happened_test_and_clear(u8 irq)88 static inline bool irq_happened_test_and_clear(u8 irq)
89 {
90 if (local_paca->irq_happened & irq) {
91 local_paca->irq_happened &= ~irq;
92 return true;
93 }
94 return false;
95 }
96
__replay_soft_interrupts(void)97 static __no_kcsan void __replay_soft_interrupts(void)
98 {
99 struct pt_regs regs;
100
101 /*
102 * We use local_paca rather than get_paca() to avoid all the
103 * debug_smp_processor_id() business in this low level function.
104 */
105
106 if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
107 WARN_ON_ONCE(mfmsr() & MSR_EE);
108 WARN_ON(!(local_paca->irq_happened & PACA_IRQ_HARD_DIS));
109 WARN_ON(local_paca->irq_happened & PACA_IRQ_REPLAYING);
110 }
111
112 /*
113 * PACA_IRQ_REPLAYING prevents interrupt handlers from enabling
114 * MSR[EE] to get PMIs, which can result in more IRQs becoming
115 * pending.
116 */
117 local_paca->irq_happened |= PACA_IRQ_REPLAYING;
118
119 ppc_save_regs(®s);
120 regs.softe = IRQS_ENABLED;
121 regs.msr |= MSR_EE;
122
123 /*
124 * Force the delivery of pending soft-disabled interrupts on PS3.
125 * Any HV call will have this side effect.
126 */
127 if (firmware_has_feature(FW_FEATURE_PS3_LV1)) {
128 u64 tmp, tmp2;
129 lv1_get_version_info(&tmp, &tmp2);
130 }
131
132 /*
133 * Check if an hypervisor Maintenance interrupt happened.
134 * This is a higher priority interrupt than the others, so
135 * replay it first.
136 */
137 if (IS_ENABLED(CONFIG_PPC_BOOK3S) &&
138 irq_happened_test_and_clear(PACA_IRQ_HMI)) {
139 regs.trap = INTERRUPT_HMI;
140 handle_hmi_exception(®s);
141 next_interrupt(®s);
142 }
143
144 if (irq_happened_test_and_clear(PACA_IRQ_DEC)) {
145 regs.trap = INTERRUPT_DECREMENTER;
146 timer_interrupt(®s);
147 next_interrupt(®s);
148 }
149
150 if (irq_happened_test_and_clear(PACA_IRQ_EE)) {
151 regs.trap = INTERRUPT_EXTERNAL;
152 do_IRQ(®s);
153 next_interrupt(®s);
154 }
155
156 if (IS_ENABLED(CONFIG_PPC_DOORBELL) &&
157 irq_happened_test_and_clear(PACA_IRQ_DBELL)) {
158 regs.trap = INTERRUPT_DOORBELL;
159 doorbell_exception(®s);
160 next_interrupt(®s);
161 }
162
163 /* Book3E does not support soft-masking PMI interrupts */
164 if (IS_ENABLED(CONFIG_PPC_BOOK3S) &&
165 irq_happened_test_and_clear(PACA_IRQ_PMI)) {
166 regs.trap = INTERRUPT_PERFMON;
167 performance_monitor_exception(®s);
168 next_interrupt(®s);
169 }
170
171 local_paca->irq_happened &= ~PACA_IRQ_REPLAYING;
172 }
173
replay_soft_interrupts(void)174 __no_kcsan void replay_soft_interrupts(void)
175 {
176 irq_enter(); /* See comment in arch_local_irq_restore */
177 __replay_soft_interrupts();
178 irq_exit();
179 }
180
181 #if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_PPC_KUAP)
replay_soft_interrupts_irqrestore(void)182 static inline __no_kcsan void replay_soft_interrupts_irqrestore(void)
183 {
184 unsigned long kuap_state = get_kuap();
185
186 /*
187 * Check if anything calls local_irq_enable/restore() when KUAP is
188 * disabled (user access enabled). We handle that case here by saving
189 * and re-locking AMR but we shouldn't get here in the first place,
190 * hence the warning.
191 */
192 kuap_assert_locked();
193
194 if (kuap_state != AMR_KUAP_BLOCKED)
195 set_kuap(AMR_KUAP_BLOCKED);
196
197 __replay_soft_interrupts();
198
199 if (kuap_state != AMR_KUAP_BLOCKED)
200 set_kuap(kuap_state);
201 }
202 #else
203 #define replay_soft_interrupts_irqrestore() __replay_soft_interrupts()
204 #endif
205
arch_local_irq_restore(unsigned long mask)206 notrace __no_kcsan void arch_local_irq_restore(unsigned long mask)
207 {
208 unsigned char irq_happened;
209
210 /* Write the new soft-enabled value if it is a disable */
211 if (mask) {
212 irq_soft_mask_set(mask);
213 return;
214 }
215
216 if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
217 WARN_ON_ONCE(in_nmi());
218 WARN_ON_ONCE(in_hardirq());
219 WARN_ON_ONCE(local_paca->irq_happened & PACA_IRQ_REPLAYING);
220 }
221
222 again:
223 /*
224 * After the stb, interrupts are unmasked and there are no interrupts
225 * pending replay. The restart sequence makes this atomic with
226 * respect to soft-masked interrupts. If this was just a simple code
227 * sequence, a soft-masked interrupt could become pending right after
228 * the comparison and before the stb.
229 *
230 * This allows interrupts to be unmasked without hard disabling, and
231 * also without new hard interrupts coming in ahead of pending ones.
232 */
233 asm_volatile_goto(
234 "1: \n"
235 " lbz 9,%0(13) \n"
236 " cmpwi 9,0 \n"
237 " bne %l[happened] \n"
238 " stb 9,%1(13) \n"
239 "2: \n"
240 RESTART_TABLE(1b, 2b, 1b)
241 : : "i" (offsetof(struct paca_struct, irq_happened)),
242 "i" (offsetof(struct paca_struct, irq_soft_mask))
243 : "cr0", "r9"
244 : happened);
245
246 if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
247 WARN_ON_ONCE(!(mfmsr() & MSR_EE));
248
249 /*
250 * If we came here from the replay below, we might have a preempt
251 * pending (due to preempt_enable_no_resched()). Have to check now.
252 */
253 preempt_check_resched();
254
255 return;
256
257 happened:
258 irq_happened = READ_ONCE(local_paca->irq_happened);
259 if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
260 WARN_ON_ONCE(!irq_happened);
261
262 if (irq_happened == PACA_IRQ_HARD_DIS) {
263 if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
264 WARN_ON_ONCE(mfmsr() & MSR_EE);
265 irq_soft_mask_set(IRQS_ENABLED);
266 local_paca->irq_happened = 0;
267 __hard_irq_enable();
268 preempt_check_resched();
269 return;
270 }
271
272 /* Have interrupts to replay, need to hard disable first */
273 if (!(irq_happened & PACA_IRQ_HARD_DIS)) {
274 if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
275 if (!(mfmsr() & MSR_EE)) {
276 /*
277 * An interrupt could have come in and cleared
278 * MSR[EE] and set IRQ_HARD_DIS, so check
279 * IRQ_HARD_DIS again and warn if it is still
280 * clear.
281 */
282 irq_happened = READ_ONCE(local_paca->irq_happened);
283 WARN_ON_ONCE(!(irq_happened & PACA_IRQ_HARD_DIS));
284 }
285 }
286 __hard_irq_disable();
287 local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
288 } else {
289 if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
290 if (WARN_ON_ONCE(mfmsr() & MSR_EE))
291 __hard_irq_disable();
292 }
293 }
294
295 /*
296 * Disable preempt here, so that the below preempt_enable will
297 * perform resched if required (a replayed interrupt may set
298 * need_resched).
299 */
300 preempt_disable();
301 irq_soft_mask_set(IRQS_ALL_DISABLED);
302 trace_hardirqs_off();
303
304 /*
305 * Now enter interrupt context. The interrupt handlers themselves
306 * also call irq_enter/exit (which is okay, they can nest). But call
307 * it here now to hold off softirqs until the below irq_exit(). If
308 * we allowed replayed handlers to run softirqs, that enables irqs,
309 * which must replay interrupts, which recurses in here and makes
310 * things more complicated. The recursion is limited to 2, and it can
311 * be made to work, but it's complicated.
312 *
313 * local_bh_disable can not be used here because interrupts taken in
314 * idle are not in the right context (RCU, tick, etc) to run softirqs
315 * so irq_enter must be called.
316 */
317 irq_enter();
318
319 replay_soft_interrupts_irqrestore();
320
321 irq_exit();
322
323 if (unlikely(local_paca->irq_happened != PACA_IRQ_HARD_DIS)) {
324 /*
325 * The softirq processing in irq_exit() may enable interrupts
326 * temporarily, which can result in MSR[EE] being enabled and
327 * more irqs becoming pending. Go around again if that happens.
328 */
329 trace_hardirqs_on();
330 preempt_enable_no_resched();
331 goto again;
332 }
333
334 trace_hardirqs_on();
335 irq_soft_mask_set(IRQS_ENABLED);
336 local_paca->irq_happened = 0;
337 __hard_irq_enable();
338 preempt_enable();
339 }
340 EXPORT_SYMBOL(arch_local_irq_restore);
341
342 /*
343 * This is a helper to use when about to go into idle low-power
344 * when the latter has the side effect of re-enabling interrupts
345 * (such as calling H_CEDE under pHyp).
346 *
347 * You call this function with interrupts soft-disabled (this is
348 * already the case when ppc_md.power_save is called). The function
349 * will return whether to enter power save or just return.
350 *
351 * In the former case, it will have generally sanitized the lazy irq
352 * state, and in the latter case it will leave with interrupts hard
353 * disabled and marked as such, so the local_irq_enable() call
354 * in arch_cpu_idle() will properly re-enable everything.
355 */
prep_irq_for_idle(void)356 __cpuidle bool prep_irq_for_idle(void)
357 {
358 /*
359 * First we need to hard disable to ensure no interrupt
360 * occurs before we effectively enter the low power state
361 */
362 __hard_irq_disable();
363 local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
364
365 /*
366 * If anything happened while we were soft-disabled,
367 * we return now and do not enter the low power state.
368 */
369 if (lazy_irq_pending())
370 return false;
371
372 /*
373 * Mark interrupts as soft-enabled and clear the
374 * PACA_IRQ_HARD_DIS from the pending mask since we
375 * are about to hard enable as well as a side effect
376 * of entering the low power state.
377 */
378 local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
379 irq_soft_mask_set(IRQS_ENABLED);
380
381 /* Tell the caller to enter the low power state */
382 return true;
383 }
384
385 #ifdef CONFIG_PPC_BOOK3S
386 /*
387 * This is for idle sequences that return with IRQs off, but the
388 * idle state itself wakes on interrupt. Tell the irq tracer that
389 * IRQs are enabled for the duration of idle so it does not get long
390 * off times. Must be paired with fini_irq_for_idle_irqsoff.
391 */
prep_irq_for_idle_irqsoff(void)392 bool prep_irq_for_idle_irqsoff(void)
393 {
394 WARN_ON(!irqs_disabled());
395
396 /*
397 * First we need to hard disable to ensure no interrupt
398 * occurs before we effectively enter the low power state
399 */
400 __hard_irq_disable();
401 local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
402
403 /*
404 * If anything happened while we were soft-disabled,
405 * we return now and do not enter the low power state.
406 */
407 if (lazy_irq_pending())
408 return false;
409
410 /* Tell lockdep we are about to re-enable */
411 trace_hardirqs_on();
412
413 return true;
414 }
415
416 /*
417 * Take the SRR1 wakeup reason, index into this table to find the
418 * appropriate irq_happened bit.
419 *
420 * Sytem reset exceptions taken in idle state also come through here,
421 * but they are NMI interrupts so do not need to wait for IRQs to be
422 * restored, and should be taken as early as practical. These are marked
423 * with 0xff in the table. The Power ISA specifies 0100b as the system
424 * reset interrupt reason.
425 */
426 #define IRQ_SYSTEM_RESET 0xff
427
428 static const u8 srr1_to_lazyirq[0x10] = {
429 0, 0, 0,
430 PACA_IRQ_DBELL,
431 IRQ_SYSTEM_RESET,
432 PACA_IRQ_DBELL,
433 PACA_IRQ_DEC,
434 0,
435 PACA_IRQ_EE,
436 PACA_IRQ_EE,
437 PACA_IRQ_HMI,
438 0, 0, 0, 0, 0 };
439
replay_system_reset(void)440 void replay_system_reset(void)
441 {
442 struct pt_regs regs;
443
444 ppc_save_regs(®s);
445 regs.trap = 0x100;
446 get_paca()->in_nmi = 1;
447 system_reset_exception(®s);
448 get_paca()->in_nmi = 0;
449 }
450 EXPORT_SYMBOL_GPL(replay_system_reset);
451
irq_set_pending_from_srr1(unsigned long srr1)452 void irq_set_pending_from_srr1(unsigned long srr1)
453 {
454 unsigned int idx = (srr1 & SRR1_WAKEMASK_P8) >> 18;
455 u8 reason = srr1_to_lazyirq[idx];
456
457 /*
458 * Take the system reset now, which is immediately after registers
459 * are restored from idle. It's an NMI, so interrupts need not be
460 * re-enabled before it is taken.
461 */
462 if (unlikely(reason == IRQ_SYSTEM_RESET)) {
463 replay_system_reset();
464 return;
465 }
466
467 if (reason == PACA_IRQ_DBELL) {
468 /*
469 * When doorbell triggers a system reset wakeup, the message
470 * is not cleared, so if the doorbell interrupt is replayed
471 * and the IPI handled, the doorbell interrupt would still
472 * fire when EE is enabled.
473 *
474 * To avoid taking the superfluous doorbell interrupt,
475 * execute a msgclr here before the interrupt is replayed.
476 */
477 ppc_msgclr(PPC_DBELL_MSGTYPE);
478 }
479
480 /*
481 * The 0 index (SRR1[42:45]=b0000) must always evaluate to 0,
482 * so this can be called unconditionally with the SRR1 wake
483 * reason as returned by the idle code, which uses 0 to mean no
484 * interrupt.
485 *
486 * If a future CPU was to designate this as an interrupt reason,
487 * then a new index for no interrupt must be assigned.
488 */
489 local_paca->irq_happened |= reason;
490 }
491 #endif /* CONFIG_PPC_BOOK3S */
492
493 /*
494 * Force a replay of the external interrupt handler on this CPU.
495 */
force_external_irq_replay(void)496 void force_external_irq_replay(void)
497 {
498 /*
499 * This must only be called with interrupts soft-disabled,
500 * the replay will happen when re-enabling.
501 */
502 WARN_ON(!arch_irqs_disabled());
503
504 /*
505 * Interrupts must always be hard disabled before irq_happened is
506 * modified (to prevent lost update in case of interrupt between
507 * load and store).
508 */
509 __hard_irq_disable();
510 local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
511
512 /* Indicate in the PACA that we have an interrupt to replay */
513 local_paca->irq_happened |= PACA_IRQ_EE;
514 }
515
setup_noirqdistrib(char * str)516 static int __init setup_noirqdistrib(char *str)
517 {
518 distribute_irqs = 0;
519 return 1;
520 }
521
522 __setup("noirqdistrib", setup_noirqdistrib);
523
