summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/kernel/irq_64.c
blob: 9dc0ad3c533a8f0f737f58fed9e6f41eae207cc1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Derived from arch/i386/kernel/irq.c
 *    Copyright (C) 1992 Linus Torvalds
 *  Adapted from arch/i386 by Gary Thomas
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *  Updated and modified by Cort Dougan <cort@fsmlabs.com>
 *    Copyright (C) 1996-2001 Cort Dougan
 *  Adapted for Power Macintosh by Paul Mackerras
 *    Copyright (C) 1996 Paul Mackerras (paulus@cs.anu.edu.au)
 *
 * This file contains the code used by various IRQ handling routines:
 * asking for different IRQ's should be done through these routines
 * instead of just grabbing them. Thus setups with different IRQ numbers
 * shouldn't result in any weird surprises, and installing new handlers
 * should be easier.
 */

#undef DEBUG

#include <linux/export.h>
#include <linux/threads.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/seq_file.h>
#include <linux/cpumask.h>
#include <linux/profile.h>
#include <linux/bitops.h>
#include <linux/list.h>
#include <linux/radix-tree.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/debugfs.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/vmalloc.h>
#include <linux/pgtable.h>
#include <linux/static_call.h>

#include <linux/uaccess.h>
#include <asm/interrupt.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/cache.h>
#include <asm/ptrace.h>
#include <asm/machdep.h>
#include <asm/udbg.h>
#include <asm/smp.h>
#include <asm/hw_irq.h>
#include <asm/softirq_stack.h>
#include <asm/ppc_asm.h>

#include <asm/paca.h>
#include <asm/firmware.h>
#include <asm/lv1call.h>
#include <asm/dbell.h>
#include <asm/trace.h>
#include <asm/cpu_has_feature.h>

int distribute_irqs = 1;

static inline void next_interrupt(struct pt_regs *regs)
{
	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
		WARN_ON(!(local_paca->irq_happened & PACA_IRQ_HARD_DIS));
		WARN_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED);
	}

	/*
	 * We are responding to the next interrupt, so interrupt-off
	 * latencies should be reset here.
	 */
	lockdep_hardirq_exit();
	trace_hardirqs_on();
	trace_hardirqs_off();
	lockdep_hardirq_enter();
}

static inline bool irq_happened_test_and_clear(u8 irq)
{
	if (local_paca->irq_happened & irq) {
		local_paca->irq_happened &= ~irq;
		return true;
	}
	return false;
}

static void __replay_soft_interrupts(void)
{
	struct pt_regs regs;

	/*
	 * We use local_paca rather than get_paca() to avoid all the
	 * debug_smp_processor_id() business in this low level function.
	 */

	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
		WARN_ON_ONCE(mfmsr() & MSR_EE);
		WARN_ON(!(local_paca->irq_happened & PACA_IRQ_HARD_DIS));
		WARN_ON(local_paca->irq_happened & PACA_IRQ_REPLAYING);
	}

	/*
	 * PACA_IRQ_REPLAYING prevents interrupt handlers from enabling
	 * MSR[EE] to get PMIs, which can result in more IRQs becoming
	 * pending.
	 */
	local_paca->irq_happened |= PACA_IRQ_REPLAYING;

	ppc_save_regs(&regs);
	regs.softe = IRQS_ENABLED;
	regs.msr |= MSR_EE;

	/*
	 * Force the delivery of pending soft-disabled interrupts on PS3.
	 * Any HV call will have this side effect.
	 */
	if (firmware_has_feature(FW_FEATURE_PS3_LV1)) {
		u64 tmp, tmp2;
		lv1_get_version_info(&tmp, &tmp2);
	}

	/*
	 * Check if an hypervisor Maintenance interrupt happened.
	 * This is a higher priority interrupt than the others, so
	 * replay it first.
	 */
	if (IS_ENABLED(CONFIG_PPC_BOOK3S) &&
	    irq_happened_test_and_clear(PACA_IRQ_HMI)) {
		regs.trap = INTERRUPT_HMI;
		handle_hmi_exception(&regs);
		next_interrupt(&regs);
	}

	if (irq_happened_test_and_clear(PACA_IRQ_DEC)) {
		regs.trap = INTERRUPT_DECREMENTER;
		timer_interrupt(&regs);
		next_interrupt(&regs);
	}

	if (irq_happened_test_and_clear(PACA_IRQ_EE)) {
		regs.trap = INTERRUPT_EXTERNAL;
		do_IRQ(&regs);
		next_interrupt(&regs);
	}

	if (IS_ENABLED(CONFIG_PPC_DOORBELL) &&
	    irq_happened_test_and_clear(PACA_IRQ_DBELL)) {
		regs.trap = INTERRUPT_DOORBELL;
		doorbell_exception(&regs);
		next_interrupt(&regs);
	}

	/* Book3E does not support soft-masking PMI interrupts */
	if (IS_ENABLED(CONFIG_PPC_BOOK3S) &&
	    irq_happened_test_and_clear(PACA_IRQ_PMI)) {
		regs.trap = INTERRUPT_PERFMON;
		performance_monitor_exception(&regs);
		next_interrupt(&regs);
	}

	local_paca->irq_happened &= ~PACA_IRQ_REPLAYING;
}

void replay_soft_interrupts(void)
{
	irq_enter(); /* See comment in arch_local_irq_restore */
	__replay_soft_interrupts();
	irq_exit();
}

#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_PPC_KUAP)
static inline void replay_soft_interrupts_irqrestore(void)
{
	unsigned long kuap_state = get_kuap();

	/*
	 * Check if anything calls local_irq_enable/restore() when KUAP is
	 * disabled (user access enabled). We handle that case here by saving
	 * and re-locking AMR but we shouldn't get here in the first place,
	 * hence the warning.
	 */
	kuap_assert_locked();

	if (kuap_state != AMR_KUAP_BLOCKED)
		set_kuap(AMR_KUAP_BLOCKED);

	__replay_soft_interrupts();

	if (kuap_state != AMR_KUAP_BLOCKED)
		set_kuap(kuap_state);
}
#else
#define replay_soft_interrupts_irqrestore() __replay_soft_interrupts()
#endif

notrace void arch_local_irq_restore(unsigned long mask)
{
	unsigned char irq_happened;

	/* Write the new soft-enabled value if it is a disable */
	if (mask) {
		irq_soft_mask_set(mask);
		return;
	}

	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
		WARN_ON_ONCE(in_nmi());
		WARN_ON_ONCE(in_hardirq());
		WARN_ON_ONCE(local_paca->irq_happened & PACA_IRQ_REPLAYING);
	}

again:
	/*
	 * After the stb, interrupts are unmasked and there are no interrupts
	 * pending replay. The restart sequence makes this atomic with
	 * respect to soft-masked interrupts. If this was just a simple code
	 * sequence, a soft-masked interrupt could become pending right after
	 * the comparison and before the stb.
	 *
	 * This allows interrupts to be unmasked without hard disabling, and
	 * also without new hard interrupts coming in ahead of pending ones.
	 */
	asm_volatile_goto(
"1:					\n"
"		lbz	9,%0(13)	\n"
"		cmpwi	9,0		\n"
"		bne	%l[happened]	\n"
"		stb	9,%1(13)	\n"
"2:					\n"
		RESTART_TABLE(1b, 2b, 1b)
	: : "i" (offsetof(struct paca_struct, irq_happened)),
	    "i" (offsetof(struct paca_struct, irq_soft_mask))
	: "cr0", "r9"
	: happened);

	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
		WARN_ON_ONCE(!(mfmsr() & MSR_EE));

	/*
	 * If we came here from the replay below, we might have a preempt
	 * pending (due to preempt_enable_no_resched()). Have to check now.
	 */
	preempt_check_resched();

	return;

happened:
	irq_happened = READ_ONCE(local_paca->irq_happened);
	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
		WARN_ON_ONCE(!irq_happened);

	if (irq_happened == PACA_IRQ_HARD_DIS) {
		if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
			WARN_ON_ONCE(mfmsr() & MSR_EE);
		irq_soft_mask_set(IRQS_ENABLED);
		local_paca->irq_happened = 0;
		__hard_irq_enable();
		preempt_check_resched();
		return;
	}

	/* Have interrupts to replay, need to hard disable first */
	if (!(irq_happened & PACA_IRQ_HARD_DIS)) {
		if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
			if (!(mfmsr() & MSR_EE)) {
				/*
				 * An interrupt could have come in and cleared
				 * MSR[EE] and set IRQ_HARD_DIS, so check
				 * IRQ_HARD_DIS again and warn if it is still
				 * clear.
				 */
				irq_happened = READ_ONCE(local_paca->irq_happened);
				WARN_ON_ONCE(!(irq_happened & PACA_IRQ_HARD_DIS));
			}
		}
		__hard_irq_disable();
		local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
	} else {
		if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
			if (WARN_ON_ONCE(mfmsr() & MSR_EE))
				__hard_irq_disable();
		}
	}

	/*
	 * Disable preempt here, so that the below preempt_enable will
	 * perform resched if required (a replayed interrupt may set
	 * need_resched).
	 */
	preempt_disable();
	irq_soft_mask_set(IRQS_ALL_DISABLED);
	trace_hardirqs_off();

	/*
	 * Now enter interrupt context. The interrupt handlers themselves
	 * also call irq_enter/exit (which is okay, they can nest). But call
	 * it here now to hold off softirqs until the below irq_exit(). If
	 * we allowed replayed handlers to run softirqs, that enables irqs,
	 * which must replay interrupts, which recurses in here and makes
	 * things more complicated. The recursion is limited to 2, and it can
	 * be made to work, but it's complicated.
	 *
	 * local_bh_disable can not be used here because interrupts taken in
	 * idle are not in the right context (RCU, tick, etc) to run softirqs
	 * so irq_enter must be called.
	 */
	irq_enter();

	replay_soft_interrupts_irqrestore();

	irq_exit();

	if (unlikely(local_paca->irq_happened != PACA_IRQ_HARD_DIS)) {
		/*
		 * The softirq processing in irq_exit() may enable interrupts
		 * temporarily, which can result in MSR[EE] being enabled and
		 * more irqs becoming pending. Go around again if that happens.
		 */
		trace_hardirqs_on();
		preempt_enable_no_resched();
		goto again;
	}

	trace_hardirqs_on();
	irq_soft_mask_set(IRQS_ENABLED);
	local_paca->irq_happened = 0;
	__hard_irq_enable();
	preempt_enable();
}
EXPORT_SYMBOL(arch_local_irq_restore);

/*
 * This is a helper to use when about to go into idle low-power
 * when the latter has the side effect of re-enabling interrupts
 * (such as calling H_CEDE under pHyp).
 *
 * You call this function with interrupts soft-disabled (this is
 * already the case when ppc_md.power_save is called). The function
 * will return whether to enter power save or just return.
 *
 * In the former case, it will have notified lockdep of interrupts
 * being re-enabled and generally sanitized the lazy irq state,
 * and in the latter case it will leave with interrupts hard
 * disabled and marked as such, so the local_irq_enable() call
 * in arch_cpu_idle() will properly re-enable everything.
 */
bool prep_irq_for_idle(void)
{
	/*
	 * First we need to hard disable to ensure no interrupt
	 * occurs before we effectively enter the low power state
	 */
	__hard_irq_disable();
	local_paca->irq_happened |= PACA_IRQ_HARD_DIS;

	/*
	 * If anything happened while we were soft-disabled,
	 * we return now and do not enter the low power state.
	 */
	if (lazy_irq_pending())
		return false;

	/* Tell lockdep we are about to re-enable */
	trace_hardirqs_on();

	/*
	 * Mark interrupts as soft-enabled and clear the
	 * PACA_IRQ_HARD_DIS from the pending mask since we
	 * are about to hard enable as well as a side effect
	 * of entering the low power state.
	 */
	local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
	irq_soft_mask_set(IRQS_ENABLED);

	/* Tell the caller to enter the low power state */
	return true;
}

#ifdef CONFIG_PPC_BOOK3S
/*
 * This is for idle sequences that return with IRQs off, but the
 * idle state itself wakes on interrupt. Tell the irq tracer that
 * IRQs are enabled for the duration of idle so it does not get long
 * off times. Must be paired with fini_irq_for_idle_irqsoff.
 */
bool prep_irq_for_idle_irqsoff(void)
{
	WARN_ON(!irqs_disabled());

	/*
	 * First we need to hard disable to ensure no interrupt
	 * occurs before we effectively enter the low power state
	 */
	__hard_irq_disable();
	local_paca->irq_happened |= PACA_IRQ_HARD_DIS;

	/*
	 * If anything happened while we were soft-disabled,
	 * we return now and do not enter the low power state.
	 */
	if (lazy_irq_pending())
		return false;

	/* Tell lockdep we are about to re-enable */
	trace_hardirqs_on();

	return true;
}

/*
 * Take the SRR1 wakeup reason, index into this table to find the
 * appropriate irq_happened bit.
 *
 * Sytem reset exceptions taken in idle state also come through here,
 * but they are NMI interrupts so do not need to wait for IRQs to be
 * restored, and should be taken as early as practical. These are marked
 * with 0xff in the table. The Power ISA specifies 0100b as the system
 * reset interrupt reason.
 */
#define IRQ_SYSTEM_RESET	0xff

static const u8 srr1_to_lazyirq[0x10] = {
	0, 0, 0,
	PACA_IRQ_DBELL,
	IRQ_SYSTEM_RESET,
	PACA_IRQ_DBELL,
	PACA_IRQ_DEC,
	0,
	PACA_IRQ_EE,
	PACA_IRQ_EE,
	PACA_IRQ_HMI,
	0, 0, 0, 0, 0 };

void replay_system_reset(void)
{
	struct pt_regs regs;

	ppc_save_regs(&regs);
	regs.trap = 0x100;
	get_paca()->in_nmi = 1;
	system_reset_exception(&regs);
	get_paca()->in_nmi = 0;
}
EXPORT_SYMBOL_GPL(replay_system_reset);

void irq_set_pending_from_srr1(unsigned long srr1)
{
	unsigned int idx = (srr1 & SRR1_WAKEMASK_P8) >> 18;
	u8 reason = srr1_to_lazyirq[idx];

	/*
	 * Take the system reset now, which is immediately after registers
	 * are restored from idle. It's an NMI, so interrupts need not be
	 * re-enabled before it is taken.
	 */
	if (unlikely(reason == IRQ_SYSTEM_RESET)) {
		replay_system_reset();
		return;
	}

	if (reason == PACA_IRQ_DBELL) {
		/*
		 * When doorbell triggers a system reset wakeup, the message
		 * is not cleared, so if the doorbell interrupt is replayed
		 * and the IPI handled, the doorbell interrupt would still
		 * fire when EE is enabled.
		 *
		 * To avoid taking the superfluous doorbell interrupt,
		 * execute a msgclr here before the interrupt is replayed.
		 */
		ppc_msgclr(PPC_DBELL_MSGTYPE);
	}

	/*
	 * The 0 index (SRR1[42:45]=b0000) must always evaluate to 0,
	 * so this can be called unconditionally with the SRR1 wake
	 * reason as returned by the idle code, which uses 0 to mean no
	 * interrupt.
	 *
	 * If a future CPU was to designate this as an interrupt reason,
	 * then a new index for no interrupt must be assigned.
	 */
	local_paca->irq_happened |= reason;
}
#endif /* CONFIG_PPC_BOOK3S */

/*
 * Force a replay of the external interrupt handler on this CPU.
 */
void force_external_irq_replay(void)
{
	/*
	 * This must only be called with interrupts soft-disabled,
	 * the replay will happen when re-enabling.
	 */
	WARN_ON(!arch_irqs_disabled());

	/*
	 * Interrupts must always be hard disabled before irq_happened is
	 * modified (to prevent lost update in case of interrupt between
	 * load and store).
	 */
	__hard_irq_disable();
	local_paca->irq_happened |= PACA_IRQ_HARD_DIS;

	/* Indicate in the PACA that we have an interrupt to replay */
	local_paca->irq_happened |= PACA_IRQ_EE;
}

static int __init setup_noirqdistrib(char *str)
{
	distribute_irqs = 0;
	return 1;
}

__setup("noirqdistrib", setup_noirqdistrib);