mce.c 15.1 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
/*
 * Machine check handler.
 * K8 parts Copyright 2002,2003 Andi Kleen, SuSE Labs.
 * Rest from unknown author(s). 
 * 2004 Andi Kleen. Rewrote most of it. 
 */

#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/rcupdate.h>
#include <linux/kallsyms.h>
#include <linux/sysdev.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
18 19
#include <linux/cpu.h>
#include <linux/percpu.h>
L
Linus Torvalds 已提交
20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
#include <asm/processor.h> 
#include <asm/msr.h>
#include <asm/mce.h>
#include <asm/kdebug.h>
#include <asm/uaccess.h>

#define MISC_MCELOG_MINOR 227
#define NR_BANKS 5

static int mce_dont_init;

/* 0: always panic, 1: panic if deadlock possible, 2: try to avoid panic,
   3: never panic or exit (for testing only) */
static int tolerant = 1;
static int banks;
static unsigned long bank[NR_BANKS] = { [0 ... NR_BANKS-1] = ~0UL };
static unsigned long console_logged;
static int notify_user;
38
static int rip_msr;
L
Linus Torvalds 已提交
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

/*
 * Lockless MCE logging infrastructure.
 * This avoids deadlocks on printk locks without having to break locks. Also
 * separate MCEs from kernel messages to avoid bogus bug reports.
 */

struct mce_log mcelog = { 
	MCE_LOG_SIGNATURE,
	MCE_LOG_LEN,
}; 

void mce_log(struct mce *mce)
{
	unsigned next, entry;
	mce->finished = 0;
	smp_wmb();
	for (;;) {
		entry = rcu_dereference(mcelog.next);
		/* When the buffer fills up discard new entries. Assume 
		   that the earlier errors are the more interesting. */
		if (entry >= MCE_LOG_LEN) {
			set_bit(MCE_OVERFLOW, &mcelog.flags);
			return;
		}
		/* Old left over entry. Skip. */
		if (mcelog.entry[entry].finished)
			continue;
		smp_rmb();
		next = entry + 1;
		if (cmpxchg(&mcelog.next, entry, next) == entry)
			break;
	}
	memcpy(mcelog.entry + entry, mce, sizeof(struct mce));
	smp_wmb();
	mcelog.entry[entry].finished = 1;
	smp_wmb();

	if (!test_and_set_bit(0, &console_logged))
		notify_user = 1;
}

static void print_mce(struct mce *m)
{
	printk(KERN_EMERG "\n"
	       KERN_EMERG
	       "CPU %d: Machine Check Exception: %16Lx Bank %d: %016Lx\n",
	       m->cpu, m->mcgstatus, m->bank, m->status);
	if (m->rip) {
		printk(KERN_EMERG 
		       "RIP%s %02x:<%016Lx> ",
		       !(m->mcgstatus & MCG_STATUS_EIPV) ? " !INEXACT!" : "",
		       m->cs, m->rip);
		if (m->cs == __KERNEL_CS)
			print_symbol("{%s}", m->rip);
		printk("\n");
	}
	printk(KERN_EMERG "TSC %Lx ", m->tsc); 
	if (m->addr)
		printk("ADDR %Lx ", m->addr);
	if (m->misc)
		printk("MISC %Lx ", m->misc); 	
	printk("\n");
}

static void mce_panic(char *msg, struct mce *backup, unsigned long start)
{ 
	int i;
	oops_begin();
	for (i = 0; i < MCE_LOG_LEN; i++) {
		unsigned long tsc = mcelog.entry[i].tsc;
		if (time_before(tsc, start))
			continue;
		print_mce(&mcelog.entry[i]); 
		if (backup && mcelog.entry[i].tsc == backup->tsc)
			backup = NULL;
	}
	if (backup)
		print_mce(backup);
	if (tolerant >= 3)
		printk("Fake panic: %s\n", msg);
	else
		panic(msg);
} 

static int mce_available(struct cpuinfo_x86 *c)
{
	return test_bit(X86_FEATURE_MCE, &c->x86_capability) &&
	       test_bit(X86_FEATURE_MCA, &c->x86_capability);
}

130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146
static inline void mce_get_rip(struct mce *m, struct pt_regs *regs)
{
	if (regs && (m->mcgstatus & MCG_STATUS_RIPV)) {
		m->rip = regs->rip;
		m->cs = regs->cs;
	} else {
		m->rip = 0;
		m->cs = 0;
	}
	if (rip_msr) {
		/* Assume the RIP in the MSR is exact. Is this true? */
		m->mcgstatus |= MCG_STATUS_EIPV;
		rdmsrl(rip_msr, m->rip);
		m->cs = 0;
	}
}

L
Linus Torvalds 已提交
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
/* 
 * The actual machine check handler
 */

void do_machine_check(struct pt_regs * regs, long error_code)
{
	struct mce m, panicm;
	int nowayout = (tolerant < 1); 
	int kill_it = 0;
	u64 mcestart = 0;
	int i;
	int panicm_found = 0;

	if (regs)
		notify_die(DIE_NMI, "machine check", regs, error_code, 255, SIGKILL);
	if (!banks)
		return;

	memset(&m, 0, sizeof(struct mce));
	m.cpu = hard_smp_processor_id();
	rdmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);
	if (!(m.mcgstatus & MCG_STATUS_RIPV))
		kill_it = 1;
	
	rdtscll(mcestart);
	barrier();

	for (i = 0; i < banks; i++) {
		if (!bank[i])
			continue;
		
		m.misc = 0; 
		m.addr = 0;
		m.bank = i;
		m.tsc = 0;

		rdmsrl(MSR_IA32_MC0_STATUS + i*4, m.status);
		if ((m.status & MCI_STATUS_VAL) == 0)
			continue;

		if (m.status & MCI_STATUS_EN) {
			/* In theory _OVER could be a nowayout too, but
			   assume any overflowed errors were no fatal. */
			nowayout |= !!(m.status & MCI_STATUS_PCC);
			kill_it |= !!(m.status & MCI_STATUS_UC);
		}

		if (m.status & MCI_STATUS_MISCV)
			rdmsrl(MSR_IA32_MC0_MISC + i*4, m.misc);
		if (m.status & MCI_STATUS_ADDRV)
			rdmsrl(MSR_IA32_MC0_ADDR + i*4, m.addr);

199
		mce_get_rip(&m, regs);
L
Linus Torvalds 已提交
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
		if (error_code != -1)
			rdtscll(m.tsc);
		wrmsrl(MSR_IA32_MC0_STATUS + i*4, 0);
		mce_log(&m);

		/* Did this bank cause the exception? */
		/* Assume that the bank with uncorrectable errors did it,
		   and that there is only a single one. */
		if ((m.status & MCI_STATUS_UC) && (m.status & MCI_STATUS_EN)) {
			panicm = m;
			panicm_found = 1;
		}

		tainted |= TAINT_MACHINE_CHECK;
	}

	/* Never do anything final in the polling timer */
	if (!regs)
		goto out;

	/* If we didn't find an uncorrectable error, pick
	   the last one (shouldn't happen, just being safe). */
	if (!panicm_found)
		panicm = m;
	if (nowayout)
		mce_panic("Machine check", &panicm, mcestart);
	if (kill_it) {
		int user_space = 0;

		if (m.mcgstatus & MCG_STATUS_RIPV)
			user_space = panicm.rip && (panicm.cs & 3);
		
		/* When the machine was in user space and the CPU didn't get
		   confused it's normally not necessary to panic, unless you 
		   are paranoid (tolerant == 0)

		   RED-PEN could be more tolerant for MCEs in idle,
		   but most likely they occur at boot anyways, where
		   it is best to just halt the machine. */
		if ((!user_space && (panic_on_oops || tolerant < 2)) ||
		    (unsigned)current->pid <= 1)
			mce_panic("Uncorrected machine check", &panicm, mcestart);

		/* do_exit takes an awful lot of locks and has as
		   slight risk of deadlocking. If you don't want that
		   don't set tolerant >= 2 */
		if (tolerant < 3)
			do_exit(SIGBUS);
	}

 out:
	/* Last thing done in the machine check exception to clear state. */
	wrmsrl(MSR_IA32_MCG_STATUS, 0);
}

/*
 * Periodic polling timer for "silent" machine check errors.
 */

static int check_interval = 5 * 60; /* 5 minutes */
static void mcheck_timer(void *data);
static DECLARE_WORK(mcheck_work, mcheck_timer, NULL);

static void mcheck_check_cpu(void *info)
{
	if (mce_available(&current_cpu_data))
		do_machine_check(NULL, 0);
}

static void mcheck_timer(void *data)
{
	on_each_cpu(mcheck_check_cpu, NULL, 1, 1);
	schedule_delayed_work(&mcheck_work, check_interval * HZ);

	/*
	 * It's ok to read stale data here for notify_user and
	 * console_logged as we'll simply get the updated versions
	 * on the next mcheck_timer execution and atomic operations
	 * on console_logged act as synchronization for notify_user
	 * writes.
	 */
	if (notify_user && console_logged) {
		notify_user = 0;
		clear_bit(0, &console_logged);
		printk(KERN_INFO "Machine check events logged\n");
	}
}


static __init int periodic_mcheck_init(void)
{ 
	if (check_interval)
		schedule_delayed_work(&mcheck_work, check_interval*HZ);
	return 0;
} 
__initcall(periodic_mcheck_init);


/* 
 * Initialize Machine Checks for a CPU.
 */
static void mce_init(void *dummy)
{
	u64 cap;
	int i;

	rdmsrl(MSR_IA32_MCG_CAP, cap);
	banks = cap & 0xff;
	if (banks > NR_BANKS) { 
		printk(KERN_INFO "MCE: warning: using only %d banks\n", banks);
		banks = NR_BANKS; 
	}
312 313 314
	/* Use accurate RIP reporting if available. */
	if ((cap & (1<<9)) && ((cap >> 16) & 0xff) >= 9)
		rip_msr = MSR_IA32_MCG_EIP;
L
Linus Torvalds 已提交
315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331

	/* Log the machine checks left over from the previous reset.
	   This also clears all registers */
	do_machine_check(NULL, -1);

	set_in_cr4(X86_CR4_MCE);

	if (cap & MCG_CTL_P)
		wrmsr(MSR_IA32_MCG_CTL, 0xffffffff, 0xffffffff);

	for (i = 0; i < banks; i++) {
		wrmsrl(MSR_IA32_MC0_CTL+4*i, bank[i]);
		wrmsrl(MSR_IA32_MC0_STATUS+4*i, 0);
	}	
}

/* Add per CPU specific workarounds here */
332
static void __cpuinit mce_cpu_quirks(struct cpuinfo_x86 *c)
L
Linus Torvalds 已提交
333 334 335 336 337 338 339 340 341
{ 
	/* This should be disabled by the BIOS, but isn't always */
	if (c->x86_vendor == X86_VENDOR_AMD && c->x86 == 15) {
		/* disable GART TBL walk error reporting, which trips off 
		   incorrectly with the IOMMU & 3ware & Cerberus. */
		clear_bit(10, &bank[4]);
	}
}			

342
static void __cpuinit mce_cpu_features(struct cpuinfo_x86 *c)
L
Linus Torvalds 已提交
343 344 345 346 347 348 349 350 351 352 353 354 355 356
{
	switch (c->x86_vendor) {
	case X86_VENDOR_INTEL:
		mce_intel_feature_init(c);
		break;
	default:
		break;
	}
}

/* 
 * Called for each booted CPU to set up machine checks.
 * Must be called with preempt off. 
 */
357
void __cpuinit mcheck_init(struct cpuinfo_x86 *c)
L
Linus Torvalds 已提交
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
{
	static cpumask_t mce_cpus __initdata = CPU_MASK_NONE;

	mce_cpu_quirks(c); 

	if (mce_dont_init ||
	    cpu_test_and_set(smp_processor_id(), mce_cpus) ||
	    !mce_available(c))
		return;

	mce_init(NULL);
	mce_cpu_features(c);
}

/*
 * Character device to read and clear the MCE log.
 */

static void collect_tscs(void *data) 
{ 
	unsigned long *cpu_tsc = (unsigned long *)data;
	rdtscll(cpu_tsc[smp_processor_id()]);
} 

static ssize_t mce_read(struct file *filp, char __user *ubuf, size_t usize, loff_t *off)
{
384
	unsigned long *cpu_tsc;
L
Linus Torvalds 已提交
385 386 387 388 389
	static DECLARE_MUTEX(mce_read_sem);
	unsigned next;
	char __user *buf = ubuf;
	int i, err;

390 391 392 393
	cpu_tsc = kmalloc(NR_CPUS * sizeof(long), GFP_KERNEL);
	if (!cpu_tsc)
		return -ENOMEM;

L
Linus Torvalds 已提交
394 395 396 397 398 399
	down(&mce_read_sem); 
	next = rcu_dereference(mcelog.next);

	/* Only supports full reads right now */
	if (*off != 0 || usize < MCE_LOG_LEN*sizeof(struct mce)) { 
		up(&mce_read_sem);
400
		kfree(cpu_tsc);
L
Linus Torvalds 已提交
401 402 403 404 405 406 407 408 409 410 411 412 413 414 415
		return -EINVAL;
	}

	err = 0;
	for (i = 0; i < next; i++) {
		if (!mcelog.entry[i].finished)
			continue;
		smp_rmb();
		err |= copy_to_user(buf, mcelog.entry + i, sizeof(struct mce));
		buf += sizeof(struct mce); 
	} 

	memset(mcelog.entry, 0, next * sizeof(struct mce));
	mcelog.next = 0;

416
	synchronize_sched();
L
Linus Torvalds 已提交
417 418 419 420 421 422 423 424 425 426 427 428 429 430

	/* Collect entries that were still getting written before the synchronize. */

	on_each_cpu(collect_tscs, cpu_tsc, 1, 1);
	for (i = next; i < MCE_LOG_LEN; i++) { 
		if (mcelog.entry[i].finished && 
		    mcelog.entry[i].tsc < cpu_tsc[mcelog.entry[i].cpu]) {  
			err |= copy_to_user(buf, mcelog.entry+i, sizeof(struct mce));
			smp_rmb();
			buf += sizeof(struct mce);
			memset(&mcelog.entry[i], 0, sizeof(struct mce));
		}
	} 	
	up(&mce_read_sem);
431
	kfree(cpu_tsc);
L
Linus Torvalds 已提交
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
	return err ? -EFAULT : buf - ubuf; 
}

static int mce_ioctl(struct inode *i, struct file *f,unsigned int cmd, unsigned long arg)
{
	int __user *p = (int __user *)arg;
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM; 
	switch (cmd) {
	case MCE_GET_RECORD_LEN: 
		return put_user(sizeof(struct mce), p);
	case MCE_GET_LOG_LEN:
		return put_user(MCE_LOG_LEN, p);		
	case MCE_GETCLEAR_FLAGS: {
		unsigned flags;
		do { 
			flags = mcelog.flags;
		} while (cmpxchg(&mcelog.flags, flags, 0) != flags); 
		return put_user(flags, p); 
	}
	default:
		return -ENOTTY; 
	} 
}

static struct file_operations mce_chrdev_ops = {
	.read = mce_read,
	.ioctl = mce_ioctl,
};

static struct miscdevice mce_log_device = {
	MISC_MCELOG_MINOR,
	"mcelog",
	&mce_chrdev_ops,
};

/* 
 * Old style boot options parsing. Only for compatibility. 
 */

static int __init mcheck_disable(char *str)
{
	mce_dont_init = 1;
	return 0;
}

/* mce=off disables machine check. Note you can reenable it later
   using sysfs */
static int __init mcheck_enable(char *str)
{
	if (!strcmp(str, "off"))
		mce_dont_init = 1;
	else
		printk("mce= argument %s ignored. Please use /sys", str); 
	return 0;
}

__setup("nomce", mcheck_disable);
__setup("mce", mcheck_enable);

/* 
 * Sysfs support
 */ 

/* On resume clear all MCE state. Don't want to see leftovers from the BIOS. */
static int mce_resume(struct sys_device *dev)
{
	on_each_cpu(mce_init, NULL, 1, 1);
	return 0;
}

/* Reinit MCEs after user configuration changes */
static void mce_restart(void) 
{ 
	if (check_interval)
		cancel_delayed_work(&mcheck_work);
	/* Timer race is harmless here */
	on_each_cpu(mce_init, NULL, 1, 1);       
	if (check_interval)
		schedule_delayed_work(&mcheck_work, check_interval*HZ);
}

static struct sysdev_class mce_sysclass = {
	.resume = mce_resume,
	set_kset_name("machinecheck"),
};

519
static DEFINE_PER_CPU(struct sys_device, device_mce);
L
Linus Torvalds 已提交
520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543

/* Why are there no generic functions for this? */
#define ACCESSOR(name, var, start) \
	static ssize_t show_ ## name(struct sys_device *s, char *buf) { 	   	   \
		return sprintf(buf, "%lx\n", (unsigned long)var);		   \
	} 									   \
	static ssize_t set_ ## name(struct sys_device *s,const char *buf,size_t siz) { \
		char *end; 							   \
		unsigned long new = simple_strtoul(buf, &end, 0); 		   \
		if (end == buf) return -EINVAL;					   \
		var = new;							   \
		start; 								   \
		return end-buf;		     					   \
	}									   \
	static SYSDEV_ATTR(name, 0644, show_ ## name, set_ ## name);

ACCESSOR(bank0ctl,bank[0],mce_restart())
ACCESSOR(bank1ctl,bank[1],mce_restart())
ACCESSOR(bank2ctl,bank[2],mce_restart())
ACCESSOR(bank3ctl,bank[3],mce_restart())
ACCESSOR(bank4ctl,bank[4],mce_restart())
ACCESSOR(tolerant,tolerant,)
ACCESSOR(check_interval,check_interval,mce_restart())

544 545
/* Per cpu sysdev init.  All of the cpus still share the same ctl bank */
static __cpuinit int mce_create_device(unsigned int cpu)
L
Linus Torvalds 已提交
546 547
{
	int err;
548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609
	if (!mce_available(&cpu_data[cpu]))
		return -EIO;

	per_cpu(device_mce,cpu).id = cpu;
	per_cpu(device_mce,cpu).cls = &mce_sysclass;

	err = sysdev_register(&per_cpu(device_mce,cpu));

	if (!err) {
		sysdev_create_file(&per_cpu(device_mce,cpu), &attr_bank0ctl);
		sysdev_create_file(&per_cpu(device_mce,cpu), &attr_bank1ctl);
		sysdev_create_file(&per_cpu(device_mce,cpu), &attr_bank2ctl);
		sysdev_create_file(&per_cpu(device_mce,cpu), &attr_bank3ctl);
		sysdev_create_file(&per_cpu(device_mce,cpu), &attr_bank4ctl);
		sysdev_create_file(&per_cpu(device_mce,cpu), &attr_tolerant);
		sysdev_create_file(&per_cpu(device_mce,cpu), &attr_check_interval);
	}
	return err;
}

#ifdef CONFIG_HOTPLUG_CPU
static __cpuinit void mce_remove_device(unsigned int cpu)
{
	sysdev_remove_file(&per_cpu(device_mce,cpu), &attr_bank0ctl);
	sysdev_remove_file(&per_cpu(device_mce,cpu), &attr_bank1ctl);
	sysdev_remove_file(&per_cpu(device_mce,cpu), &attr_bank2ctl);
	sysdev_remove_file(&per_cpu(device_mce,cpu), &attr_bank3ctl);
	sysdev_remove_file(&per_cpu(device_mce,cpu), &attr_bank4ctl);
	sysdev_remove_file(&per_cpu(device_mce,cpu), &attr_tolerant);
	sysdev_remove_file(&per_cpu(device_mce,cpu), &attr_check_interval);
	sysdev_unregister(&per_cpu(device_mce,cpu));
}
#endif

/* Get notified when a cpu comes on/off. Be hotplug friendly. */
static __cpuinit int
mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
	unsigned int cpu = (unsigned long)hcpu;

	switch (action) {
	case CPU_ONLINE:
		mce_create_device(cpu);
		break;
#ifdef CONFIG_HOTPLUG_CPU
	case CPU_DEAD:
		mce_remove_device(cpu);
		break;
#endif
	}
	return NOTIFY_OK;
}

static struct notifier_block mce_cpu_notifier = {
	.notifier_call = mce_cpu_callback,
};

static __init int mce_init_device(void)
{
	int err;
	int i = 0;

L
Linus Torvalds 已提交
610 611 612
	if (!mce_available(&boot_cpu_data))
		return -EIO;
	err = sysdev_class_register(&mce_sysclass);
613 614 615 616 617 618

	for_each_online_cpu(i) {
		mce_create_device(i);
	}

	register_cpu_notifier(&mce_cpu_notifier);
L
Linus Torvalds 已提交
619 620 621
	misc_register(&mce_log_device);
	return err;
}
622

L
Linus Torvalds 已提交
623
device_initcall(mce_init_device);