1/*
2 *  drivers/s390/s390mach.c
3 *   S/390 machine check handler
4 *
5 *  S390 version
6 *    Copyright (C) 2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
7 *    Author(s): Ingo Adlung (adlung@de.ibm.com)
8 *		 Martin Schwidefsky (schwidefsky@de.ibm.com)
9 */
10
11#include <linux/init.h>
12#include <linux/sched.h>
13#include <linux/errno.h>
14#include <linux/workqueue.h>
15#include <linux/time.h>
16#include <linux/device.h>
17#include <linux/kthread.h>
18#include <asm/etr.h>
19#include <asm/lowcore.h>
20#include <asm/cio.h>
21#include "cio/cio.h"
22#include "cio/chsc.h"
23#include "cio/css.h"
24#include "cio/chp.h"
25#include "s390mach.h"
26
27static struct semaphore m_sem;
28
29static NORET_TYPE void
30s390_handle_damage(char *msg)
31{
32#ifdef CONFIG_SMP
33	smp_send_stop();
34#endif
35	disabled_wait((unsigned long) __builtin_return_address(0));
36	for(;;);
37}
38
39/*
40 * Retrieve CRWs and call function to handle event.
41 *
42 * Note : we currently process CRWs for io and chsc subchannels only
43 */
44static int
45s390_collect_crw_info(void *param)
46{
47	struct crw crw[2];
48	int ccode;
49	struct semaphore *sem;
50	unsigned int chain;
51
52	sem = (struct semaphore *)param;
53repeat:
54	down_interruptible(sem);
55	chain = 0;
56	while (1) {
57		if (unlikely(chain > 1)) {
58			struct crw tmp_crw;
59
60			printk(KERN_WARNING"%s: Code does not support more "
61			       "than two chained crws; please report to "
62			       "linux390@de.ibm.com!\n", __FUNCTION__);
63			ccode = stcrw(&tmp_crw);
64			printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
65			       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
66			       __FUNCTION__, tmp_crw.slct, tmp_crw.oflw,
67			       tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
68			       tmp_crw.erc, tmp_crw.rsid);
69			printk(KERN_WARNING"%s: This was crw number %x in the "
70			       "chain\n", __FUNCTION__, chain);
71			if (ccode != 0)
72				break;
73			chain = tmp_crw.chn ? chain + 1 : 0;
74			continue;
75		}
76		ccode = stcrw(&crw[chain]);
77		if (ccode != 0)
78			break;
79		printk(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
80		       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
81		       crw[chain].slct, crw[chain].oflw, crw[chain].chn,
82		       crw[chain].rsc, crw[chain].anc, crw[chain].erc,
83		       crw[chain].rsid);
84		/* Check for overflows. */
85		if (crw[chain].oflw) {
86			pr_debug("%s: crw overflow detected!\n", __FUNCTION__);
87			css_schedule_eval_all();
88			chain = 0;
89			continue;
90		}
91		switch (crw[chain].rsc) {
92		case CRW_RSC_SCH:
93			if (crw[0].chn && !chain)
94				break;
95			pr_debug("source is subchannel %04X\n", crw[0].rsid);
96			css_process_crw(crw[0].rsid, chain ? crw[1].rsid : 0);
97			break;
98		case CRW_RSC_MONITOR:
99			pr_debug("source is monitoring facility\n");
100			break;
101		case CRW_RSC_CPATH:
102			pr_debug("source is channel path %02X\n", crw[0].rsid);
103			/*
104			 * Check for solicited machine checks. These are
105			 * created by reset channel path and need not be
106			 * reported to the common I/O layer.
107			 */
108			if (crw[chain].slct) {
109				pr_debug("solicited machine check for "
110					 "channel path %02X\n", crw[0].rsid);
111				break;
112			}
113			switch (crw[0].erc) {
114			case CRW_ERC_IPARM: /* Path has come. */
115				chp_process_crw(crw[0].rsid, 1);
116				break;
117			case CRW_ERC_PERRI: /* Path has gone. */
118			case CRW_ERC_PERRN:
119				chp_process_crw(crw[0].rsid, 0);
120				break;
121			default:
122				pr_debug("Don't know how to handle erc=%x\n",
123					 crw[0].erc);
124			}
125			break;
126		case CRW_RSC_CONFIG:
127			pr_debug("source is configuration-alert facility\n");
128			break;
129		case CRW_RSC_CSS:
130			pr_debug("source is channel subsystem\n");
131			chsc_process_crw();
132			break;
133		default:
134			pr_debug("unknown source\n");
135			break;
136		}
137		/* chain is always 0 or 1 here. */
138		chain = crw[chain].chn ? chain + 1 : 0;
139	}
140	goto repeat;
141	return 0;
142}
143
144struct mcck_struct {
145	int kill_task;
146	int channel_report;
147	int warning;
148	unsigned long long mcck_code;
149};
150
151static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
152
153/*
154 * Main machine check handler function. Will be called with interrupts enabled
155 * or disabled and machine checks enabled or disabled.
156 */
157void
158s390_handle_mcck(void)
159{
160	unsigned long flags;
161	struct mcck_struct mcck;
162
163	/*
164	 * Disable machine checks and get the current state of accumulated
165	 * machine checks. Afterwards delete the old state and enable machine
166	 * checks again.
167	 */
168	local_irq_save(flags);
169	local_mcck_disable();
170	mcck = __get_cpu_var(cpu_mcck);
171	memset(&__get_cpu_var(cpu_mcck), 0, sizeof(struct mcck_struct));
172	clear_thread_flag(TIF_MCCK_PENDING);
173	local_mcck_enable();
174	local_irq_restore(flags);
175
176	if (mcck.channel_report)
177		up(&m_sem);
178
179#ifdef CONFIG_MACHCHK_WARNING
180/*
181 * The warning may remain for a prolonged period on the bare iron.
182 * (actually till the machine is powered off, or until the problem is gone)
183 * So we just stop listening for the WARNING MCH and prevent continuously
184 * being interrupted.  One caveat is however, that we must do this per
185 * processor and cannot use the smp version of ctl_clear_bit().
186 * On VM we only get one interrupt per virtally presented machinecheck.
187 * Though one suffices, we may get one interrupt per (virtual) processor.
188 */
189	if (mcck.warning) {	/* WARNING pending ? */
190		static int mchchk_wng_posted = 0;
191		/*
192		 * Use single machine clear, as we cannot handle smp right now
193		 */
194		__ctl_clear_bit(14, 24);	/* Disable WARNING MCH */
195		if (xchg(&mchchk_wng_posted, 1) == 0)
196			kill_cad_pid(SIGPWR, 1);
197	}
198#endif
199
200	if (mcck.kill_task) {
201		local_irq_enable();
202		printk(KERN_EMERG "mcck: Terminating task because of machine "
203		       "malfunction (code 0x%016llx).\n", mcck.mcck_code);
204		printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
205		       current->comm, current->pid);
206		do_exit(SIGSEGV);
207	}
208}
209
210/*
211 * returns 0 if all registers could be validated
212 * returns 1 otherwise
213 */
214static int
215s390_revalidate_registers(struct mci *mci)
216{
217	int kill_task;
218	u64 tmpclock;
219	u64 zero;
220	void *fpt_save_area, *fpt_creg_save_area;
221
222	kill_task = 0;
223	zero = 0;
224	/* General purpose registers */
225	if (!mci->gr)
226		/*
227		 * General purpose registers couldn't be restored and have
228		 * unknown contents. Process needs to be terminated.
229		 */
230		kill_task = 1;
231
232	/* Revalidate floating point registers */
233	if (!mci->fp)
234		/*
235		 * Floating point registers can't be restored and
236		 * therefore the process needs to be terminated.
237		 */
238		kill_task = 1;
239
240#ifndef CONFIG_64BIT
241	asm volatile(
242		"	ld	0,0(%0)\n"
243		"	ld	2,8(%0)\n"
244		"	ld	4,16(%0)\n"
245		"	ld	6,24(%0)"
246		: : "a" (&S390_lowcore.floating_pt_save_area));
247#endif
248
249	if (MACHINE_HAS_IEEE) {
250#ifdef CONFIG_64BIT
251		fpt_save_area = &S390_lowcore.floating_pt_save_area;
252		fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
253#else
254		fpt_save_area = (void *) S390_lowcore.extended_save_area_addr;
255		fpt_creg_save_area = fpt_save_area+128;
256#endif
257		/* Floating point control register */
258		if (!mci->fc) {
259			/*
260			 * Floating point control register can't be restored.
261			 * Task will be terminated.
262			 */
263			asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
264			kill_task = 1;
265
266		} else
267			asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
268
269		asm volatile(
270			"	ld	0,0(%0)\n"
271			"	ld	1,8(%0)\n"
272			"	ld	2,16(%0)\n"
273			"	ld	3,24(%0)\n"
274			"	ld	4,32(%0)\n"
275			"	ld	5,40(%0)\n"
276			"	ld	6,48(%0)\n"
277			"	ld	7,56(%0)\n"
278			"	ld	8,64(%0)\n"
279			"	ld	9,72(%0)\n"
280			"	ld	10,80(%0)\n"
281			"	ld	11,88(%0)\n"
282			"	ld	12,96(%0)\n"
283			"	ld	13,104(%0)\n"
284			"	ld	14,112(%0)\n"
285			"	ld	15,120(%0)\n"
286			: : "a" (fpt_save_area));
287	}
288
289	/* Revalidate access registers */
290	asm volatile(
291		"	lam	0,15,0(%0)"
292		: : "a" (&S390_lowcore.access_regs_save_area));
293	if (!mci->ar)
294		/*
295		 * Access registers have unknown contents.
296		 * Terminating task.
297		 */
298		kill_task = 1;
299
300	/* Revalidate control registers */
301	if (!mci->cr)
302		/*
303		 * Control registers have unknown contents.
304		 * Can't recover and therefore stopping machine.
305		 */
306		s390_handle_damage("invalid control registers.");
307	else
308#ifdef CONFIG_64BIT
309		asm volatile(
310			"	lctlg	0,15,0(%0)"
311			: : "a" (&S390_lowcore.cregs_save_area));
312#else
313		asm volatile(
314			"	lctl	0,15,0(%0)"
315			: : "a" (&S390_lowcore.cregs_save_area));
316#endif
317
318	/*
319	 * We don't even try to revalidate the TOD register, since we simply
320	 * can't write something sensible into that register.
321	 */
322
323#ifdef CONFIG_64BIT
324	/*
325	 * See if we can revalidate the TOD programmable register with its
326	 * old contents (should be zero) otherwise set it to zero.
327	 */
328	if (!mci->pr)
329		asm volatile(
330			"	sr	0,0\n"
331			"	sckpf"
332			: : : "0", "cc");
333	else
334		asm volatile(
335			"	l	0,0(%0)\n"
336			"	sckpf"
337			: : "a" (&S390_lowcore.tod_progreg_save_area)
338			: "0", "cc");
339#endif
340
341	/* Revalidate clock comparator register */
342	asm volatile(
343		"	stck	0(%1)\n"
344		"	sckc	0(%1)"
345		: "=m" (tmpclock) : "a" (&(tmpclock)) : "cc", "memory");
346
347	/* Check if old PSW is valid */
348	if (!mci->wp)
349		/*
350		 * Can't tell if we come from user or kernel mode
351		 * -> stopping machine.
352		 */
353		s390_handle_damage("old psw invalid.");
354
355	if (!mci->ms || !mci->pm || !mci->ia)
356		kill_task = 1;
357
358	return kill_task;
359}
360
361#define MAX_IPD_COUNT	29
362#define MAX_IPD_TIME	(5 * 60 * USEC_PER_SEC) /* 5 minutes */
363
364/*
365 * machine check handler.
366 */
367void
368s390_do_machine_check(struct pt_regs *regs)
369{
370	static DEFINE_SPINLOCK(ipd_lock);
371	static unsigned long long last_ipd;
372	static int ipd_count;
373	unsigned long long tmp;
374	struct mci *mci;
375	struct mcck_struct *mcck;
376	int umode;
377
378	lockdep_off();
379
380	mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
381	mcck = &__get_cpu_var(cpu_mcck);
382	umode = user_mode(regs);
383
384	if (mci->sd)
385		/* System damage -> stopping machine */
386		s390_handle_damage("received system damage machine check.");
387
388	if (mci->pd) {
389		if (mci->b) {
390			/* Processing backup -> verify if we can survive this */
391			u64 z_mcic, o_mcic, t_mcic;
392#ifdef CONFIG_64BIT
393			z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
394			o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
395				  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
396				  1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
397				  1ULL<<16);
398#else
399			z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<57 | 1ULL<<50 |
400				  1ULL<<29);
401			o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
402				  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
403				  1ULL<<30 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16);
404#endif
405			t_mcic = *(u64 *)mci;
406
407			if (((t_mcic & z_mcic) != 0) ||
408			    ((t_mcic & o_mcic) != o_mcic)) {
409				s390_handle_damage("processing backup machine "
410						   "check with damage.");
411			}
412
413			/*
414			 * Nullifying exigent condition, therefore we might
415			 * retry this instruction.
416			 */
417
418			spin_lock(&ipd_lock);
419
420			tmp = get_clock();
421
422			if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
423				ipd_count++;
424			else
425				ipd_count = 1;
426
427			last_ipd = tmp;
428
429			if (ipd_count == MAX_IPD_COUNT)
430				s390_handle_damage("too many ipd retries.");
431
432			spin_unlock(&ipd_lock);
433		}
434		else {
435			/* Processing damage -> stopping machine */
436			s390_handle_damage("received instruction processing "
437					   "damage machine check.");
438		}
439	}
440	if (s390_revalidate_registers(mci)) {
441		if (umode) {
442			/*
443			 * Couldn't restore all register contents while in
444			 * user mode -> mark task for termination.
445			 */
446			mcck->kill_task = 1;
447			mcck->mcck_code = *(unsigned long long *) mci;
448			set_thread_flag(TIF_MCCK_PENDING);
449		}
450		else
451			/*
452			 * Couldn't restore all register contents while in
453			 * kernel mode -> stopping machine.
454			 */
455			s390_handle_damage("unable to revalidate registers.");
456	}
457
458	if (mci->cd) {
459		/* Timing facility damage */
460		s390_handle_damage("TOD clock damaged");
461	}
462
463	if (mci->ed && mci->ec) {
464		/* External damage */
465		if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
466			etr_sync_check();
467		if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
468			etr_switch_to_local();
469	}
470
471	if (mci->se)
472		/* Storage error uncorrected */
473		s390_handle_damage("received storage error uncorrected "
474				   "machine check.");
475
476	if (mci->ke)
477		/* Storage key-error uncorrected */
478		s390_handle_damage("received storage key-error uncorrected "
479				   "machine check.");
480
481	if (mci->ds && mci->fa)
482		/* Storage degradation */
483		s390_handle_damage("received storage degradation machine "
484				   "check.");
485
486	if (mci->cp) {
487		/* Channel report word pending */
488		mcck->channel_report = 1;
489		set_thread_flag(TIF_MCCK_PENDING);
490	}
491
492	if (mci->w) {
493		/* Warning pending */
494		mcck->warning = 1;
495		set_thread_flag(TIF_MCCK_PENDING);
496	}
497	lockdep_on();
498}
499
500/*
501 * s390_init_machine_check
502 *
503 * initialize machine check handling
504 */
505static int
506machine_check_init(void)
507{
508	init_MUTEX_LOCKED(&m_sem);
509	ctl_set_bit(14, 25);	/* enable external damage MCH */
510	ctl_set_bit(14, 27);    /* enable system recovery MCH */
511#ifdef CONFIG_MACHCHK_WARNING
512	ctl_set_bit(14, 24);	/* enable warning MCH */
513#endif
514	return 0;
515}
516
517/*
518 * Initialize the machine check handler really early to be able to
519 * catch all machine checks that happen during boot
520 */
521arch_initcall(machine_check_init);
522
523/*
524 * Machine checks for the channel subsystem must be enabled
525 * after the channel subsystem is initialized
526 */
527static int __init
528machine_check_crw_init (void)
529{
530	struct task_struct *task;
531
532	task = kthread_run(s390_collect_crw_info, &m_sem, "kmcheck");
533	if (IS_ERR(task))
534		return PTR_ERR(task);
535	ctl_set_bit(14, 28);	/* enable channel report MCH */
536	return 0;
537}
538
539device_initcall (machine_check_crw_init);
540