1 /*
2  * Copyright (C) 2001 Dave Engebretsen IBM Corporation
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
17  */
18 
19 #include <linux/sched.h>
20 #include <linux/interrupt.h>
21 #include <linux/irq.h>
22 #include <linux/of.h>
23 #include <linux/fs.h>
24 #include <linux/reboot.h>
25 
26 #include <asm/machdep.h>
27 #include <asm/rtas.h>
28 #include <asm/firmware.h>
29 
30 #include "pseries.h"
31 
32 static unsigned char ras_log_buf[RTAS_ERROR_LOG_MAX];
33 static DEFINE_SPINLOCK(ras_log_buf_lock);
34 
35 static char global_mce_data_buf[RTAS_ERROR_LOG_MAX];
36 static DEFINE_PER_CPU(__u64, mce_data_buf);
37 
38 static int ras_check_exception_token;
39 
40 #define EPOW_SENSOR_TOKEN	9
41 #define EPOW_SENSOR_INDEX	0
42 
43 static irqreturn_t ras_epow_interrupt(int irq, void *dev_id);
44 static irqreturn_t ras_error_interrupt(int irq, void *dev_id);
45 
46 
47 /*
48  * Initialize handlers for the set of interrupts caused by hardware errors
49  * and power system events.
50  */
51 static int __init init_ras_IRQ(void)
52 {
53 	struct device_node *np;
54 
55 	ras_check_exception_token = rtas_token("check-exception");
56 
57 	/* Internal Errors */
58 	np = of_find_node_by_path("/event-sources/internal-errors");
59 	if (np != NULL) {
60 		request_event_sources_irqs(np, ras_error_interrupt,
61 					   "RAS_ERROR");
62 		of_node_put(np);
63 	}
64 
65 	/* EPOW Events */
66 	np = of_find_node_by_path("/event-sources/epow-events");
67 	if (np != NULL) {
68 		request_event_sources_irqs(np, ras_epow_interrupt, "RAS_EPOW");
69 		of_node_put(np);
70 	}
71 
72 	return 0;
73 }
74 machine_subsys_initcall(pseries, init_ras_IRQ);
75 
76 #define EPOW_SHUTDOWN_NORMAL				1
77 #define EPOW_SHUTDOWN_ON_UPS				2
78 #define EPOW_SHUTDOWN_LOSS_OF_CRITICAL_FUNCTIONS	3
79 #define EPOW_SHUTDOWN_AMBIENT_TEMPERATURE_TOO_HIGH	4
80 
81 static void handle_system_shutdown(char event_modifier)
82 {
83 	switch (event_modifier) {
84 	case EPOW_SHUTDOWN_NORMAL:
85 		pr_emerg("Firmware initiated power off");
86 		orderly_poweroff(true);
87 		break;
88 
89 	case EPOW_SHUTDOWN_ON_UPS:
90 		pr_emerg("Loss of power reported by firmware, system is "
91 			"running on UPS/battery");
92 		break;
93 
94 	case EPOW_SHUTDOWN_LOSS_OF_CRITICAL_FUNCTIONS:
95 		pr_emerg("Loss of system critical functions reported by "
96 			"firmware");
97 		pr_emerg("Check RTAS error log for details");
98 		orderly_poweroff(true);
99 		break;
100 
101 	case EPOW_SHUTDOWN_AMBIENT_TEMPERATURE_TOO_HIGH:
102 		pr_emerg("Ambient temperature too high reported by firmware");
103 		pr_emerg("Check RTAS error log for details");
104 		orderly_poweroff(true);
105 		break;
106 
107 	default:
108 		pr_err("Unknown power/cooling shutdown event (modifier %d)",
109 			event_modifier);
110 	}
111 }
112 
113 struct epow_errorlog {
114 	unsigned char sensor_value;
115 	unsigned char event_modifier;
116 	unsigned char extended_modifier;
117 	unsigned char reserved;
118 	unsigned char platform_reason;
119 };
120 
121 #define EPOW_RESET			0
122 #define EPOW_WARN_COOLING		1
123 #define EPOW_WARN_POWER			2
124 #define EPOW_SYSTEM_SHUTDOWN		3
125 #define EPOW_SYSTEM_HALT		4
126 #define EPOW_MAIN_ENCLOSURE		5
127 #define EPOW_POWER_OFF			7
128 
129 static void rtas_parse_epow_errlog(struct rtas_error_log *log)
130 {
131 	struct pseries_errorlog *pseries_log;
132 	struct epow_errorlog *epow_log;
133 	char action_code;
134 	char modifier;
135 
136 	pseries_log = get_pseries_errorlog(log, PSERIES_ELOG_SECT_ID_EPOW);
137 	if (pseries_log == NULL)
138 		return;
139 
140 	epow_log = (struct epow_errorlog *)pseries_log->data;
141 	action_code = epow_log->sensor_value & 0xF;	/* bottom 4 bits */
142 	modifier = epow_log->event_modifier & 0xF;	/* bottom 4 bits */
143 
144 	switch (action_code) {
145 	case EPOW_RESET:
146 		pr_err("Non critical power or cooling issue cleared");
147 		break;
148 
149 	case EPOW_WARN_COOLING:
150 		pr_err("Non critical cooling issue reported by firmware");
151 		pr_err("Check RTAS error log for details");
152 		break;
153 
154 	case EPOW_WARN_POWER:
155 		pr_err("Non critical power issue reported by firmware");
156 		pr_err("Check RTAS error log for details");
157 		break;
158 
159 	case EPOW_SYSTEM_SHUTDOWN:
160 		handle_system_shutdown(epow_log->event_modifier);
161 		break;
162 
163 	case EPOW_SYSTEM_HALT:
164 		pr_emerg("Firmware initiated power off");
165 		orderly_poweroff(true);
166 		break;
167 
168 	case EPOW_MAIN_ENCLOSURE:
169 	case EPOW_POWER_OFF:
170 		pr_emerg("Critical power/cooling issue reported by firmware");
171 		pr_emerg("Check RTAS error log for details");
172 		pr_emerg("Immediate power off");
173 		emergency_sync();
174 		kernel_power_off();
175 		break;
176 
177 	default:
178 		pr_err("Unknown power/cooling event (action code %d)",
179 			action_code);
180 	}
181 }
182 
183 /* Handle environmental and power warning (EPOW) interrupts. */
184 static irqreturn_t ras_epow_interrupt(int irq, void *dev_id)
185 {
186 	int status;
187 	int state;
188 	int critical;
189 
190 	status = rtas_get_sensor(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, &state);
191 
192 	if (state > 3)
193 		critical = 1;		/* Time Critical */
194 	else
195 		critical = 0;
196 
197 	spin_lock(&ras_log_buf_lock);
198 
199 	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
200 			   RTAS_VECTOR_EXTERNAL_INTERRUPT,
201 			   virq_to_hw(irq),
202 			   RTAS_EPOW_WARNING,
203 			   critical, __pa(&ras_log_buf),
204 				rtas_get_error_log_max());
205 
206 	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0);
207 
208 	rtas_parse_epow_errlog((struct rtas_error_log *)ras_log_buf);
209 
210 	spin_unlock(&ras_log_buf_lock);
211 	return IRQ_HANDLED;
212 }
213 
214 /*
215  * Handle hardware error interrupts.
216  *
217  * RTAS check-exception is called to collect data on the exception.  If
218  * the error is deemed recoverable, we log a warning and return.
219  * For nonrecoverable errors, an error is logged and we stop all processing
220  * as quickly as possible in order to prevent propagation of the failure.
221  */
222 static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
223 {
224 	struct rtas_error_log *rtas_elog;
225 	int status;
226 	int fatal;
227 
228 	spin_lock(&ras_log_buf_lock);
229 
230 	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
231 			   RTAS_VECTOR_EXTERNAL_INTERRUPT,
232 			   virq_to_hw(irq),
233 			   RTAS_INTERNAL_ERROR, 1 /* Time Critical */,
234 			   __pa(&ras_log_buf),
235 				rtas_get_error_log_max());
236 
237 	rtas_elog = (struct rtas_error_log *)ras_log_buf;
238 
239 	if (status == 0 &&
240 	    rtas_error_severity(rtas_elog) >= RTAS_SEVERITY_ERROR_SYNC)
241 		fatal = 1;
242 	else
243 		fatal = 0;
244 
245 	/* format and print the extended information */
246 	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, fatal);
247 
248 	if (fatal) {
249 		pr_emerg("Fatal hardware error reported by firmware");
250 		pr_emerg("Check RTAS error log for details");
251 		pr_emerg("Immediate power off");
252 		emergency_sync();
253 		kernel_power_off();
254 	} else {
255 		pr_err("Recoverable hardware error reported by firmware");
256 	}
257 
258 	spin_unlock(&ras_log_buf_lock);
259 	return IRQ_HANDLED;
260 }
261 
262 /*
263  * Some versions of FWNMI place the buffer inside the 4kB page starting at
264  * 0x7000. Other versions place it inside the rtas buffer. We check both.
265  */
266 #define VALID_FWNMI_BUFFER(A) \
267 	((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
268 	(((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))
269 
270 /*
271  * Get the error information for errors coming through the
272  * FWNMI vectors.  The pt_regs' r3 will be updated to reflect
273  * the actual r3 if possible, and a ptr to the error log entry
274  * will be returned if found.
275  *
276  * If the RTAS error is not of the extended type, then we put it in a per
277  * cpu 64bit buffer. If it is the extended type we use global_mce_data_buf.
278  *
279  * The global_mce_data_buf does not have any locks or protection around it,
280  * if a second machine check comes in, or a system reset is done
281  * before we have logged the error, then we will get corruption in the
282  * error log.  This is preferable over holding off on calling
283  * ibm,nmi-interlock which would result in us checkstopping if a
284  * second machine check did come in.
285  */
286 static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
287 {
288 	unsigned long *savep;
289 	struct rtas_error_log *h, *errhdr = NULL;
290 
291 	/* Mask top two bits */
292 	regs->gpr[3] &= ~(0x3UL << 62);
293 
294 	if (!VALID_FWNMI_BUFFER(regs->gpr[3])) {
295 		printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
296 		return NULL;
297 	}
298 
299 	savep = __va(regs->gpr[3]);
300 	regs->gpr[3] = savep[0];	/* restore original r3 */
301 
302 	/* If it isn't an extended log we can use the per cpu 64bit buffer */
303 	h = (struct rtas_error_log *)&savep[1];
304 	if (!rtas_error_extended(h)) {
305 		memcpy(this_cpu_ptr(&mce_data_buf), h, sizeof(__u64));
306 		errhdr = (struct rtas_error_log *)this_cpu_ptr(&mce_data_buf);
307 	} else {
308 		int len, error_log_length;
309 
310 		error_log_length = 8 + rtas_error_extended_log_length(h);
311 		len = max_t(int, error_log_length, RTAS_ERROR_LOG_MAX);
312 		memset(global_mce_data_buf, 0, RTAS_ERROR_LOG_MAX);
313 		memcpy(global_mce_data_buf, h, len);
314 		errhdr = (struct rtas_error_log *)global_mce_data_buf;
315 	}
316 
317 	return errhdr;
318 }
319 
320 /* Call this when done with the data returned by FWNMI_get_errinfo.
321  * It will release the saved data area for other CPUs in the
322  * partition to receive FWNMI errors.
323  */
324 static void fwnmi_release_errinfo(void)
325 {
326 	int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
327 	if (ret != 0)
328 		printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
329 }
330 
331 int pSeries_system_reset_exception(struct pt_regs *regs)
332 {
333 	if (fwnmi_active) {
334 		struct rtas_error_log *errhdr = fwnmi_get_errinfo(regs);
335 		if (errhdr) {
336 			/* XXX Should look at FWNMI information */
337 		}
338 		fwnmi_release_errinfo();
339 	}
340 	return 0; /* need to perform reset */
341 }
342 
343 /*
344  * See if we can recover from a machine check exception.
345  * This is only called on power4 (or above) and only via
346  * the Firmware Non-Maskable Interrupts (fwnmi) handler
347  * which provides the error analysis for us.
348  *
349  * Return 1 if corrected (or delivered a signal).
350  * Return 0 if there is nothing we can do.
351  */
352 static int recover_mce(struct pt_regs *regs, struct rtas_error_log *err)
353 {
354 	int recovered = 0;
355 	int disposition = rtas_error_disposition(err);
356 
357 	if (!(regs->msr & MSR_RI)) {
358 		/* If MSR_RI isn't set, we cannot recover */
359 		recovered = 0;
360 
361 	} else if (disposition == RTAS_DISP_FULLY_RECOVERED) {
362 		/* Platform corrected itself */
363 		recovered = 1;
364 
365 	} else if (disposition == RTAS_DISP_LIMITED_RECOVERY) {
366 		/* Platform corrected itself but could be degraded */
367 		printk(KERN_ERR "MCE: limited recovery, system may "
368 		       "be degraded\n");
369 		recovered = 1;
370 
371 	} else if (user_mode(regs) && !is_global_init(current) &&
372 		   rtas_error_severity(err) == RTAS_SEVERITY_ERROR_SYNC) {
373 
374 		/*
375 		 * If we received a synchronous error when in userspace
376 		 * kill the task. Firmware may report details of the fail
377 		 * asynchronously, so we can't rely on the target and type
378 		 * fields being valid here.
379 		 */
380 		printk(KERN_ERR "MCE: uncorrectable error, killing task "
381 		       "%s:%d\n", current->comm, current->pid);
382 
383 		_exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
384 		recovered = 1;
385 	}
386 
387 	log_error((char *)err, ERR_TYPE_RTAS_LOG, 0);
388 
389 	return recovered;
390 }
391 
392 /*
393  * Handle a machine check.
394  *
395  * Note that on Power 4 and beyond Firmware Non-Maskable Interrupts (fwnmi)
396  * should be present.  If so the handler which called us tells us if the
397  * error was recovered (never true if RI=0).
398  *
399  * On hardware prior to Power 4 these exceptions were asynchronous which
400  * means we can't tell exactly where it occurred and so we can't recover.
401  */
402 int pSeries_machine_check_exception(struct pt_regs *regs)
403 {
404 	struct rtas_error_log *errp;
405 
406 	if (fwnmi_active) {
407 		errp = fwnmi_get_errinfo(regs);
408 		fwnmi_release_errinfo();
409 		if (errp && recover_mce(regs, errp))
410 			return 1;
411 	}
412 
413 	return 0;
414 }
415