1 /*
2 * Machine check handler
3 *
4 * Copyright IBM Corp. 2000, 2009
5 * Author(s): Ingo Adlung <adlung@de.ibm.com>,
6 * Martin Schwidefsky <schwidefsky@de.ibm.com>,
7 * Cornelia Huck <cornelia.huck@de.ibm.com>,
8 * Heiko Carstens <heiko.carstens@de.ibm.com>,
9 */
10
11 #include <linux/kernel_stat.h>
12 #include <linux/init.h>
13 #include <linux/errno.h>
14 #include <linux/hardirq.h>
15 #include <linux/time.h>
16 #include <linux/module.h>
17 #include <asm/lowcore.h>
18 #include <asm/smp.h>
19 #include <asm/etr.h>
20 #include <asm/cputime.h>
21 #include <asm/nmi.h>
22 #include <asm/crw.h>
23
24 struct mcck_struct {
25 int kill_task;
26 int channel_report;
27 int warning;
28 unsigned long long mcck_code;
29 };
30
31 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
32
s390_handle_damage(char * msg)33 static void s390_handle_damage(char *msg)
34 {
35 smp_send_stop();
36 disabled_wait((unsigned long) __builtin_return_address(0));
37 while (1);
38 }
39
40 /*
41 * Main machine check handler function. Will be called with interrupts enabled
42 * or disabled and machine checks enabled or disabled.
43 */
s390_handle_mcck(void)44 void s390_handle_mcck(void)
45 {
46 unsigned long flags;
47 struct mcck_struct mcck;
48
49 /*
50 * Disable machine checks and get the current state of accumulated
51 * machine checks. Afterwards delete the old state and enable machine
52 * checks again.
53 */
54 local_irq_save(flags);
55 local_mcck_disable();
56 mcck = __get_cpu_var(cpu_mcck);
57 memset(&__get_cpu_var(cpu_mcck), 0, sizeof(struct mcck_struct));
58 clear_thread_flag(TIF_MCCK_PENDING);
59 local_mcck_enable();
60 local_irq_restore(flags);
61
62 if (mcck.channel_report)
63 crw_handle_channel_report();
64 /*
65 * A warning may remain for a prolonged period on the bare iron.
66 * (actually until the machine is powered off, or the problem is gone)
67 * So we just stop listening for the WARNING MCH and avoid continuously
68 * being interrupted. One caveat is however, that we must do this per
69 * processor and cannot use the smp version of ctl_clear_bit().
70 * On VM we only get one interrupt per virtally presented machinecheck.
71 * Though one suffices, we may get one interrupt per (virtual) cpu.
72 */
73 if (mcck.warning) { /* WARNING pending ? */
74 static int mchchk_wng_posted = 0;
75
76 /* Use single cpu clear, as we cannot handle smp here. */
77 __ctl_clear_bit(14, 24); /* Disable WARNING MCH */
78 if (xchg(&mchchk_wng_posted, 1) == 0)
79 kill_cad_pid(SIGPWR, 1);
80 }
81 if (mcck.kill_task) {
82 local_irq_enable();
83 printk(KERN_EMERG "mcck: Terminating task because of machine "
84 "malfunction (code 0x%016llx).\n", mcck.mcck_code);
85 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
86 current->comm, current->pid);
87 do_exit(SIGSEGV);
88 }
89 }
90 EXPORT_SYMBOL_GPL(s390_handle_mcck);
91
92 /*
93 * returns 0 if all registers could be validated
94 * returns 1 otherwise
95 */
s390_revalidate_registers(struct mci * mci)96 static int notrace s390_revalidate_registers(struct mci *mci)
97 {
98 int kill_task;
99 u64 zero;
100 void *fpt_save_area, *fpt_creg_save_area;
101
102 kill_task = 0;
103 zero = 0;
104
105 if (!mci->gr) {
106 /*
107 * General purpose registers couldn't be restored and have
108 * unknown contents. Process needs to be terminated.
109 */
110 kill_task = 1;
111 }
112 if (!mci->fp) {
113 /*
114 * Floating point registers can't be restored and
115 * therefore the process needs to be terminated.
116 */
117 kill_task = 1;
118 }
119 #ifndef CONFIG_64BIT
120 asm volatile(
121 " ld 0,0(%0)\n"
122 " ld 2,8(%0)\n"
123 " ld 4,16(%0)\n"
124 " ld 6,24(%0)"
125 : : "a" (&S390_lowcore.floating_pt_save_area));
126 #endif
127
128 if (MACHINE_HAS_IEEE) {
129 #ifdef CONFIG_64BIT
130 fpt_save_area = &S390_lowcore.floating_pt_save_area;
131 fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
132 #else
133 fpt_save_area = (void *) S390_lowcore.extended_save_area_addr;
134 fpt_creg_save_area = fpt_save_area + 128;
135 #endif
136 if (!mci->fc) {
137 /*
138 * Floating point control register can't be restored.
139 * Task will be terminated.
140 */
141 asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
142 kill_task = 1;
143
144 } else
145 asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
146
147 asm volatile(
148 " ld 0,0(%0)\n"
149 " ld 1,8(%0)\n"
150 " ld 2,16(%0)\n"
151 " ld 3,24(%0)\n"
152 " ld 4,32(%0)\n"
153 " ld 5,40(%0)\n"
154 " ld 6,48(%0)\n"
155 " ld 7,56(%0)\n"
156 " ld 8,64(%0)\n"
157 " ld 9,72(%0)\n"
158 " ld 10,80(%0)\n"
159 " ld 11,88(%0)\n"
160 " ld 12,96(%0)\n"
161 " ld 13,104(%0)\n"
162 " ld 14,112(%0)\n"
163 " ld 15,120(%0)\n"
164 : : "a" (fpt_save_area));
165 }
166 /* Revalidate access registers */
167 asm volatile(
168 " lam 0,15,0(%0)"
169 : : "a" (&S390_lowcore.access_regs_save_area));
170 if (!mci->ar) {
171 /*
172 * Access registers have unknown contents.
173 * Terminating task.
174 */
175 kill_task = 1;
176 }
177 /* Revalidate control registers */
178 if (!mci->cr) {
179 /*
180 * Control registers have unknown contents.
181 * Can't recover and therefore stopping machine.
182 */
183 s390_handle_damage("invalid control registers.");
184 } else {
185 #ifdef CONFIG_64BIT
186 asm volatile(
187 " lctlg 0,15,0(%0)"
188 : : "a" (&S390_lowcore.cregs_save_area));
189 #else
190 asm volatile(
191 " lctl 0,15,0(%0)"
192 : : "a" (&S390_lowcore.cregs_save_area));
193 #endif
194 }
195 /*
196 * We don't even try to revalidate the TOD register, since we simply
197 * can't write something sensible into that register.
198 */
199 #ifdef CONFIG_64BIT
200 /*
201 * See if we can revalidate the TOD programmable register with its
202 * old contents (should be zero) otherwise set it to zero.
203 */
204 if (!mci->pr)
205 asm volatile(
206 " sr 0,0\n"
207 " sckpf"
208 : : : "0", "cc");
209 else
210 asm volatile(
211 " l 0,0(%0)\n"
212 " sckpf"
213 : : "a" (&S390_lowcore.tod_progreg_save_area)
214 : "0", "cc");
215 #endif
216 /* Revalidate clock comparator register */
217 if (S390_lowcore.clock_comparator == -1)
218 set_clock_comparator(S390_lowcore.mcck_clock);
219 else
220 set_clock_comparator(S390_lowcore.clock_comparator);
221 /* Check if old PSW is valid */
222 if (!mci->wp)
223 /*
224 * Can't tell if we come from user or kernel mode
225 * -> stopping machine.
226 */
227 s390_handle_damage("old psw invalid.");
228
229 if (!mci->ms || !mci->pm || !mci->ia)
230 kill_task = 1;
231
232 return kill_task;
233 }
234
235 #define MAX_IPD_COUNT 29
236 #define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */
237
238 #define ED_STP_ISLAND 6 /* External damage STP island check */
239 #define ED_STP_SYNC 7 /* External damage STP sync check */
240 #define ED_ETR_SYNC 12 /* External damage ETR sync check */
241 #define ED_ETR_SWITCH 13 /* External damage ETR switch to local */
242
243 /*
244 * machine check handler.
245 */
s390_do_machine_check(struct pt_regs * regs)246 void notrace s390_do_machine_check(struct pt_regs *regs)
247 {
248 static int ipd_count;
249 static DEFINE_SPINLOCK(ipd_lock);
250 static unsigned long long last_ipd;
251 struct mcck_struct *mcck;
252 unsigned long long tmp;
253 struct mci *mci;
254 int umode;
255
256 nmi_enter();
257 inc_irq_stat(NMI_NMI);
258 mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
259 mcck = &__get_cpu_var(cpu_mcck);
260 umode = user_mode(regs);
261
262 if (mci->sd) {
263 /* System damage -> stopping machine */
264 s390_handle_damage("received system damage machine check.");
265 }
266 if (mci->pd) {
267 if (mci->b) {
268 /* Processing backup -> verify if we can survive this */
269 u64 z_mcic, o_mcic, t_mcic;
270 #ifdef CONFIG_64BIT
271 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
272 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
273 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
274 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
275 1ULL<<16);
276 #else
277 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<57 | 1ULL<<50 |
278 1ULL<<29);
279 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
280 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
281 1ULL<<30 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16);
282 #endif
283 t_mcic = *(u64 *)mci;
284
285 if (((t_mcic & z_mcic) != 0) ||
286 ((t_mcic & o_mcic) != o_mcic)) {
287 s390_handle_damage("processing backup machine "
288 "check with damage.");
289 }
290
291 /*
292 * Nullifying exigent condition, therefore we might
293 * retry this instruction.
294 */
295 spin_lock(&ipd_lock);
296 tmp = get_tod_clock();
297 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
298 ipd_count++;
299 else
300 ipd_count = 1;
301 last_ipd = tmp;
302 if (ipd_count == MAX_IPD_COUNT)
303 s390_handle_damage("too many ipd retries.");
304 spin_unlock(&ipd_lock);
305 } else {
306 /* Processing damage -> stopping machine */
307 s390_handle_damage("received instruction processing "
308 "damage machine check.");
309 }
310 }
311 if (s390_revalidate_registers(mci)) {
312 if (umode) {
313 /*
314 * Couldn't restore all register contents while in
315 * user mode -> mark task for termination.
316 */
317 mcck->kill_task = 1;
318 mcck->mcck_code = *(unsigned long long *) mci;
319 set_thread_flag(TIF_MCCK_PENDING);
320 } else {
321 /*
322 * Couldn't restore all register contents while in
323 * kernel mode -> stopping machine.
324 */
325 s390_handle_damage("unable to revalidate registers.");
326 }
327 }
328 if (mci->cd) {
329 /* Timing facility damage */
330 s390_handle_damage("TOD clock damaged");
331 }
332 if (mci->ed && mci->ec) {
333 /* External damage */
334 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
335 etr_sync_check();
336 if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
337 etr_switch_to_local();
338 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
339 stp_sync_check();
340 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
341 stp_island_check();
342 }
343 if (mci->se)
344 /* Storage error uncorrected */
345 s390_handle_damage("received storage error uncorrected "
346 "machine check.");
347 if (mci->ke)
348 /* Storage key-error uncorrected */
349 s390_handle_damage("received storage key-error uncorrected "
350 "machine check.");
351 if (mci->ds && mci->fa)
352 /* Storage degradation */
353 s390_handle_damage("received storage degradation machine "
354 "check.");
355 if (mci->cp) {
356 /* Channel report word pending */
357 mcck->channel_report = 1;
358 set_thread_flag(TIF_MCCK_PENDING);
359 }
360 if (mci->w) {
361 /* Warning pending */
362 mcck->warning = 1;
363 set_thread_flag(TIF_MCCK_PENDING);
364 }
365 nmi_exit();
366 }
367
machine_check_init(void)368 static int __init machine_check_init(void)
369 {
370 ctl_set_bit(14, 25); /* enable external damage MCH */
371 ctl_set_bit(14, 27); /* enable system recovery MCH */
372 ctl_set_bit(14, 24); /* enable warning MCH */
373 return 0;
374 }
375 arch_initcall(machine_check_init);
376