aboutsummaryrefslogtreecommitdiff
path: root/drivers/s390/s390mach.c
blob: 92b0417f8e12069403f1d50bbfb5653913b5a8f9 (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
527
528
529
530
531
532
533
534
535
536
537
538
/*
 *  drivers/s390/s390mach.c
 *   S/390 machine check handler
 *
 *    Copyright IBM Corp. 2000,2008
 *    Author(s): Ingo Adlung (adlung@de.ibm.com)
 *		 Martin Schwidefsky (schwidefsky@de.ibm.com)
 *		 Cornelia Huck <cornelia.huck@de.ibm.com>
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/workqueue.h>
#include <linux/time.h>
#include <linux/device.h>
#include <linux/kthread.h>
#include <asm/etr.h>
#include <asm/lowcore.h>
#include <asm/cio.h>
#include <asm/cpu.h>
#include "s390mach.h"

static struct semaphore m_sem;

static NORET_TYPE void
s390_handle_damage(char *msg)
{
#ifdef CONFIG_SMP
	smp_send_stop();
#endif
	disabled_wait((unsigned long) __builtin_return_address(0));
	for(;;);
}

static crw_handler_t crw_handlers[NR_RSCS];

/**
 * s390_register_crw_handler() - register a channel report word handler
 * @rsc: reporting source code to handle
 * @handler: handler to be registered
 *
 * Returns %0 on success and a negative error value otherwise.
 */
int s390_register_crw_handler(int rsc, crw_handler_t handler)
{
	if ((rsc < 0) || (rsc >= NR_RSCS))
		return -EINVAL;
	if (!cmpxchg(&crw_handlers[rsc], NULL, handler))
		return 0;
	return -EBUSY;
}

/**
 * s390_unregister_crw_handler() - unregister a channel report word handler
 * @rsc: reporting source code to handle
 */
void s390_unregister_crw_handler(int rsc)
{
	if ((rsc < 0) || (rsc >= NR_RSCS))
		return;
	xchg(&crw_handlers[rsc], NULL);
	synchronize_sched();
}

/*
 * Retrieve CRWs and call function to handle event.
 */
static int s390_collect_crw_info(void *param)
{
	struct crw crw[2];
	int ccode;
	struct semaphore *sem;
	unsigned int chain;
	int ignore;

	sem = (struct semaphore *)param;
repeat:
	ignore = down_interruptible(sem);
	chain = 0;
	while (1) {
		if (unlikely(chain > 1)) {
			struct crw tmp_crw;

			printk(KERN_WARNING"%s: Code does not support more "
			       "than two chained crws; please report to "
			       "linux390@de.ibm.com!\n", __func__);
			ccode = stcrw(&tmp_crw);
			printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
			       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
			       __func__, tmp_crw.slct, tmp_crw.oflw,
			       tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
			       tmp_crw.erc, tmp_crw.rsid);
			printk(KERN_WARNING"%s: This was crw number %x in the "
			       "chain\n", __func__, chain);
			if (ccode != 0)
				break;
			chain = tmp_crw.chn ? chain + 1 : 0;
			continue;
		}
		ccode = stcrw(&crw[chain]);
		if (ccode != 0)
			break;
		printk(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
		       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
		       crw[chain].slct, crw[chain].oflw, crw[chain].chn,
		       crw[chain].rsc, crw[chain].anc, crw[chain].erc,
		       crw[chain].rsid);
		/* Check for overflows. */
		if (crw[chain].oflw) {
			int i;

			pr_debug("%s: crw overflow detected!\n", __func__);
			for (i = 0; i < NR_RSCS; i++) {
				if (crw_handlers[i])
					crw_handlers[i](NULL, NULL, 1);
			}
			chain = 0;
			continue;
		}
		if (crw[0].chn && !chain) {
			chain++;
			continue;
		}
		if (crw_handlers[crw[chain].rsc])
			crw_handlers[crw[chain].rsc](&crw[0],
						     chain ? &crw[1] : NULL,
						     0);
		/* chain is always 0 or 1 here. */
		chain = crw[chain].chn ? chain + 1 : 0;
	}
	goto repeat;
	return 0;
}

struct mcck_struct {
	int kill_task;
	int channel_report;
	int warning;
	unsigned long long mcck_code;
};

static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);

/*
 * Main machine check handler function. Will be called with interrupts enabled
 * or disabled and machine checks enabled or disabled.
 */
void
s390_handle_mcck(void)
{
	unsigned long flags;
	struct mcck_struct mcck;

	/*
	 * Disable machine checks and get the current state of accumulated
	 * machine checks. Afterwards delete the old state and enable machine
	 * checks again.
	 */
	local_irq_save(flags);
	local_mcck_disable();
	mcck = __get_cpu_var(cpu_mcck);
	memset(&__get_cpu_var(cpu_mcck), 0, sizeof(struct mcck_struct));
	clear_thread_flag(TIF_MCCK_PENDING);
	local_mcck_enable();
	local_irq_restore(flags);

	if (mcck.channel_report)
		up(&m_sem);

#ifdef CONFIG_MACHCHK_WARNING
/*
 * The warning may remain for a prolonged period on the bare iron.
 * (actually till the machine is powered off, or until the problem is gone)
 * So we just stop listening for the WARNING MCH and prevent continuously
 * being interrupted.  One caveat is however, that we must do this per
 * processor and cannot use the smp version of ctl_clear_bit().
 * On VM we only get one interrupt per virtally presented machinecheck.
 * Though one suffices, we may get one interrupt per (virtual) processor.
 */
	if (mcck.warning) {	/* WARNING pending ? */
		static int mchchk_wng_posted = 0;
		/*
		 * Use single machine clear, as we cannot handle smp right now
		 */
		__ctl_clear_bit(14, 24);	/* Disable WARNING MCH */
		if (xchg(&mchchk_wng_posted, 1) == 0)
			kill_cad_pid(SIGPWR, 1);
	}
#endif

	if (mcck.kill_task) {
		local_irq_enable();
		printk(KERN_EMERG "mcck: Terminating task because of machine "
		       "malfunction (code 0x%016llx).\n", mcck.mcck_code);
		printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
		       current->comm, current->pid);
		do_exit(SIGSEGV);
	}
}
EXPORT_SYMBOL_GPL(s390_handle_mcck);

/*
 * returns 0 if all registers could be validated
 * returns 1 otherwise
 */
static int
s390_revalidate_registers(struct mci *mci)
{
	int kill_task;
	u64 tmpclock;
	u64 zero;
	void *fpt_save_area, *fpt_creg_save_area;

	kill_task = 0;
	zero = 0;
	/* General purpose registers */
	if (!mci->gr)
		/*
		 * General purpose registers couldn't be restored and have
		 * unknown contents. Process needs to be terminated.
		 */
		kill_task = 1;

	/* Revalidate floating point registers */
	if (!mci->fp)
		/*
		 * Floating point registers can't be restored and
		 * therefore the process needs to be terminated.
		 */
		kill_task = 1;

#ifndef CONFIG_64BIT
	asm volatile(
		"	ld	0,0(%0)\n"
		"	ld	2,8(%0)\n"
		"	ld	4,16(%0)\n"
		"	ld	6,24(%0)"
		: : "a" (&S390_lowcore.floating_pt_save_area));
#endif

	if (MACHINE_HAS_IEEE) {
#ifdef CONFIG_64BIT
		fpt_save_area = &S390_lowcore.floating_pt_save_area;
		fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
#else
		fpt_save_area = (void *) S390_lowcore.extended_save_area_addr;
		fpt_creg_save_area = fpt_save_area+128;
#endif
		/* Floating point control register */
		if (!mci->fc) {
			/*
			 * Floating point control register can't be restored.
			 * Task will be terminated.
			 */
			asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
			kill_task = 1;

		} else
			asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));

		asm volatile(
			"	ld	0,0(%0)\n"
			"	ld	1,8(%0)\n"
			"	ld	2,16(%0)\n"
			"	ld	3,24(%0)\n"
			"	ld	4,32(%0)\n"
			"	ld	5,40(%0)\n"
			"	ld	6,48(%0)\n"
			"	ld	7,56(%0)\n"
			"	ld	8,64(%0)\n"
			"	ld	9,72(%0)\n"
			"	ld	10,80(%0)\n"
			"	ld	11,88(%0)\n"
			"	ld	12,96(%0)\n"
			"	ld	13,104(%0)\n"
			"	ld	14,112(%0)\n"
			"	ld	15,120(%0)\n"
			: : "a" (fpt_save_area));
	}

	/* Revalidate access registers */
	asm volatile(
		"	lam	0,15,0(%0)"
		: : "a" (&S390_lowcore.access_regs_save_area));
	if (!mci->ar)
		/*
		 * Access registers have unknown contents.
		 * Terminating task.
		 */
		kill_task = 1;

	/* Revalidate control registers */
	if (!mci->cr)
		/*
		 * Control registers have unknown contents.
		 * Can't recover and therefore stopping machine.
		 */
		s390_handle_damage("invalid control registers.");
	else
#ifdef CONFIG_64BIT
		asm volatile(
			"	lctlg	0,15,0(%0)"
			: : "a" (&S390_lowcore.cregs_save_area));
#else
		asm volatile(
			"	lctl	0,15,0(%0)"
			: : "a" (&S390_lowcore.cregs_save_area));
#endif

	/*
	 * We don't even try to revalidate the TOD register, since we simply
	 * can't write something sensible into that register.
	 */

#ifdef CONFIG_64BIT
	/*
	 * See if we can revalidate the TOD programmable register with its
	 * old contents (should be zero) otherwise set it to zero.
	 */
	if (!mci->pr)
		asm volatile(
			"	sr	0,0\n"
			"	sckpf"
			: : : "0", "cc");
	else
		asm volatile(
			"	l	0,0(%0)\n"
			"	sckpf"
			: : "a" (&S390_lowcore.tod_progreg_save_area)
			: "0", "cc");
#endif

	/* Revalidate clock comparator register */
	asm volatile(
		"	stck	0(%1)\n"
		"	sckc	0(%1)"
		: "=m" (tmpclock) : "a" (&(tmpclock)) : "cc", "memory");

	/* Check if old PSW is valid */
	if (!mci->wp)
		/*
		 * Can't tell if we come from user or kernel mode
		 * -> stopping machine.
		 */
		s390_handle_damage("old psw invalid.");

	if (!mci->ms || !mci->pm || !mci->ia)
		kill_task = 1;

	return kill_task;
}

#define MAX_IPD_COUNT	29
#define MAX_IPD_TIME	(5 * 60 * USEC_PER_SEC) /* 5 minutes */

/*
 * machine check handler.
 */
void
s390_do_machine_check(struct pt_regs *regs)
{
	static DEFINE_SPINLOCK(ipd_lock);
	static unsigned long long last_ipd;
	static int ipd_count;
	unsigned long long tmp;
	struct mci *mci;
	struct mcck_struct *mcck;
	int umode;

	lockdep_off();

	s390_idle_check();

	mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
	mcck = &__get_cpu_var(cpu_mcck);
	umode = user_mode(regs);

	if (mci->sd)
		/* System damage -> stopping machine */
		s390_handle_damage("received system damage machine check.");

	if (mci->pd) {
		if (mci->b) {
			/* Processing backup -> verify if we can survive this */
			u64 z_mcic, o_mcic, t_mcic;
#ifdef CONFIG_64BIT
			z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
			o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
				  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
				  1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
				  1ULL<<16);
#else
			z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<57 | 1ULL<<50 |
				  1ULL<<29);
			o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
				  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
				  1ULL<<30 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16);
#endif
			t_mcic = *(u64 *)mci;

			if (((t_mcic & z_mcic) != 0) ||
			    ((t_mcic & o_mcic) != o_mcic)) {
				s390_handle_damage("processing backup machine "
						   "check with damage.");
			}

			/*
			 * Nullifying exigent condition, therefore we might
			 * retry this instruction.
			 */

			spin_lock(&ipd_lock);

			tmp = get_clock();

			if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
				ipd_count++;
			else
				ipd_count = 1;

			last_ipd = tmp;

			if (ipd_count == MAX_IPD_COUNT)
				s390_handle_damage("too many ipd retries.");

			spin_unlock(&ipd_lock);
		}
		else {
			/* Processing damage -> stopping machine */
			s390_handle_damage("received instruction processing "
					   "damage machine check.");
		}
	}
	if (s390_revalidate_registers(mci)) {
		if (umode) {
			/*
			 * Couldn't restore all register contents while in
			 * user mode -> mark task for termination.
			 */
			mcck->kill_task = 1;
			mcck->mcck_code = *(unsigned long long *) mci;
			set_thread_flag(TIF_MCCK_PENDING);
		}
		else
			/*
			 * Couldn't restore all register contents while in
			 * kernel mode -> stopping machine.
			 */
			s390_handle_damage("unable to revalidate registers.");
	}

	if (mci->cd) {
		/* Timing facility damage */
		s390_handle_damage("TOD clock damaged");
	}

	if (mci->ed && mci->ec) {
		/* External damage */
		if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
			etr_sync_check();
		if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
			etr_switch_to_local();
		if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
			stp_sync_check();
		if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
			stp_island_check();
	}

	if (mci->se)
		/* Storage error uncorrected */
		s390_handle_damage("received storage error uncorrected "
				   "machine check.");

	if (mci->ke)
		/* Storage key-error uncorrected */
		s390_handle_damage("received storage key-error uncorrected "
				   "machine check.");

	if (mci->ds && mci->fa)
		/* Storage degradation */
		s390_handle_damage("received storage degradation machine "
				   "check.");

	if (mci->cp) {
		/* Channel report word pending */
		mcck->channel_report = 1;
		set_thread_flag(TIF_MCCK_PENDING);
	}

	if (mci->w) {
		/* Warning pending */
		mcck->warning = 1;
		set_thread_flag(TIF_MCCK_PENDING);
	}
	lockdep_on();
}

/*
 * s390_init_machine_check
 *
 * initialize machine check handling
 */
static int
machine_check_init(void)
{
	init_MUTEX_LOCKED(&m_sem);
	ctl_set_bit(14, 25);	/* enable external damage MCH */
	ctl_set_bit(14, 27);    /* enable system recovery MCH */
#ifdef CONFIG_MACHCHK_WARNING
	ctl_set_bit(14, 24);	/* enable warning MCH */
#endif
	return 0;
}

/*
 * Initialize the machine check handler really early to be able to
 * catch all machine checks that happen during boot
 */
arch_initcall(machine_check_init);

/*
 * Machine checks for the channel subsystem must be enabled
 * after the channel subsystem is initialized
 */
static int __init
machine_check_crw_init (void)
{
	struct task_struct *task;

	task = kthread_run(s390_collect_crw_info, &m_sem, "kmcheck");
	if (IS_ERR(task))
		return PTR_ERR(task);
	ctl_set_bit(14, 28);	/* enable channel report MCH */
	return 0;
}

device_initcall (machine_check_crw_init);