2 * Machine check handler.
3 * K8 parts Copyright 2002,2003 Andi Kleen, SuSE Labs.
4 * Rest from unknown author(s).
5 * 2004 Andi Kleen. Rewrote most of it.
8 #include <linux/init.h>
9 #include <linux/types.h>
10 #include <linux/kernel.h>
11 #include <linux/sched.h>
12 #include <linux/string.h>
13 #include <linux/rcupdate.h>
14 #include <linux/kallsyms.h>
15 #include <linux/sysdev.h>
16 #include <linux/miscdevice.h>
18 #include <asm/processor.h>
21 #include <asm/kdebug.h>
22 #include <asm/uaccess.h>
24 #define MISC_MCELOG_MINOR 227
27 static int mce_disabled __initdata;
28 /* 0: always panic, 1: panic if deadlock possible, 2: try to avoid panic */
29 static int tolerant = 2;
31 static unsigned long bank[NR_BANKS] = { [0 ... NR_BANKS-1] = ~0UL };
34 * Lockless MCE logging infrastructure.
35 * This avoids deadlocks on printk locks without having to break locks. Also
36 * separate MCEs from kernel messages to avoid bogus bug reports.
39 struct mce_log mcelog = {
44 static void mce_log(struct mce *mce)
51 read_barrier_depends();
52 /* When the buffer fills up discard new entries. Assume
53 that the earlier errors are the more interesting. */
54 if (entry >= MCE_LOG_LEN) {
55 set_bit(MCE_OVERFLOW, &mcelog.flags);
58 /* Old left over entry. Skip. */
59 if (mcelog.entry[entry].finished)
63 if (cmpxchg(&mcelog.next, entry, next) == entry)
66 memcpy(mcelog.entry + entry, mce, sizeof(struct mce));
68 mcelog.entry[entry].finished = 1;
72 static void print_mce(struct mce *m)
75 "CPU %d: Machine Check Exception: %16Lx Bank %d: %016Lx\n",
76 m->cpu, m->mcgstatus, m->bank, m->status);
79 "RIP%s %02x:<%016Lx> ",
80 !(m->mcgstatus & MCG_STATUS_EIPV) ? " !INEXACT!" : "",
82 if (m->cs == __KERNEL_CS)
83 print_symbol("{%s}", m->rip);
86 printk(KERN_EMERG "TSC %Lx ", m->tsc);
88 printk("ADDR %Lx ", m->addr);
90 printk("MISC %Lx ", m->misc);
94 static void mce_panic(char *msg, struct mce *backup, unsigned long start)
98 for (i = 0; i < MCE_LOG_LEN; i++) {
99 if (mcelog.entry[i].tsc < start)
101 print_mce(&mcelog.entry[i]);
102 if (mcelog.entry[i].tsc == backup->tsc)
110 static int mce_available(struct cpuinfo_x86 *c)
112 return !mce_disabled &&
113 test_bit(X86_FEATURE_MCE, &c->x86_capability) &&
114 test_bit(X86_FEATURE_MCA, &c->x86_capability);
118 * The actual machine check handler
121 void do_machine_check(struct pt_regs * regs, long error_code)
130 notify_die(DIE_NMI, "machine check", regs, error_code, 255, SIGKILL);
134 memset(&m, 0, sizeof(struct mce));
135 m.cpu = hard_smp_processor_id();
136 rdmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);
137 if (!regs && (m.mcgstatus & MCG_STATUS_MCIP))
139 if (!(m.mcgstatus & MCG_STATUS_RIPV))
149 for (i = 0; i < banks; i++) {
153 rdmsrl(MSR_IA32_MC0_STATUS + i*4, m.status);
154 if ((m.status & MCI_STATUS_VAL) == 0)
157 nowayout |= (tolerant < 1);
158 nowayout |= !!(m.status & (MCI_STATUS_OVER|MCI_STATUS_PCC));
159 kill_it |= !!(m.status & MCI_STATUS_UC);
162 if (m.status & MCI_STATUS_MISCV)
163 rdmsrl(MSR_IA32_MC0_MISC + i*4, m.misc);
164 if (m.status & MCI_STATUS_ADDRV)
165 rdmsrl(MSR_IA32_MC0_ADDR + i*4, m.addr);
168 wrmsrl(MSR_IA32_MC0_STATUS + i*4, 0);
171 wrmsrl(MSR_IA32_MCG_STATUS, 0);
173 /* Never do anything final in the polling timer */
177 mce_panic("Machine check", &m, mcestart);
179 int user_space = (m.rip && (m.cs & 3));
181 /* When the machine was in user space and the CPU didn't get
182 confused it's normally not necessary to panic, unless you
183 are paranoid (tolerant == 0)
185 RED-PEN could be more tolerant for MCEs in idle,
186 but most likely they occur at boot anyways, where
187 it is best to just halt the machine. */
188 if ((!user_space && (panic_on_oops || tolerant < 2)) ||
189 (unsigned)current->pid <= 1)
190 mce_panic("Uncorrected machine check", &m, mcestart);
192 /* do_exit takes an awful lot of locks and has as slight risk
193 of deadlocking. If you don't want that don't set tolerant >= 2 */
198 static void mce_clear_all(void)
201 for (i = 0; i < banks; i++)
202 wrmsrl(MSR_IA32_MC0_STATUS + i*4, 0);
203 wrmsrl(MSR_IA32_MCG_STATUS, 0);
207 * Periodic polling timer for "silent" machine check errors.
210 static int check_interval = 3600; /* one hour */
211 static void mcheck_timer(void *data);
212 static DECLARE_WORK(mcheck_work, mcheck_timer, NULL);
214 static void mcheck_check_cpu(void *info)
216 if (mce_available(¤t_cpu_data))
217 do_machine_check(NULL, 0);
220 static void mcheck_timer(void *data)
222 on_each_cpu(mcheck_check_cpu, NULL, 1, 1);
223 schedule_delayed_work(&mcheck_work, check_interval * HZ);
227 static __init int periodic_mcheck_init(void)
230 schedule_delayed_work(&mcheck_work, check_interval*HZ);
233 __initcall(periodic_mcheck_init);
237 * Initialize Machine Checks for a CPU.
239 static void mce_init(void *dummy)
244 rdmsrl(MSR_IA32_MCG_CAP, cap);
246 wrmsr(MSR_IA32_MCG_CTL, 0xffffffff, 0xffffffff);
249 if (banks > NR_BANKS) {
250 printk(KERN_INFO "MCE: warning: using only %d banks\n", banks);
255 for (i = 0; i < banks; i++) {
256 wrmsrl(MSR_IA32_MC0_CTL+4*i, bank[i]);
257 wrmsrl(MSR_IA32_MC0_STATUS+4*i, 0);
260 set_in_cr4(X86_CR4_MCE);
263 /* Add per CPU specific workarounds here */
264 static void __init mce_cpu_quirks(struct cpuinfo_x86 *c)
266 /* This should be disabled by the BIOS, but isn't always */
267 if (c->x86_vendor == X86_VENDOR_AMD && c->x86 == 15) {
268 /* disable GART TBL walk error reporting, which trips off
269 incorrectly with the IOMMU & 3ware & Cerberus. */
270 clear_bit(10, &bank[4]);
275 * Called for each booted CPU to set up machine checks.
276 * Must be called with preempt off.
278 void __init mcheck_init(struct cpuinfo_x86 *c)
280 static unsigned long mce_cpus __initdata = 0;
284 if (test_and_set_bit(smp_processor_id(), &mce_cpus) || !mce_available(c))
291 * Character device to read and clear the MCE log.
294 static void collect_tscs(void *data)
296 unsigned long *cpu_tsc = (unsigned long *)data;
297 rdtscll(cpu_tsc[smp_processor_id()]);
300 static ssize_t mce_read(struct file *filp, char *ubuf, size_t usize, loff_t *off)
302 unsigned long cpu_tsc[NR_CPUS];
303 static DECLARE_MUTEX(mce_read_sem);
310 read_barrier_depends();
312 /* Only supports full reads right now */
313 if (*off != 0 || usize < MCE_LOG_LEN*sizeof(struct mce)) {
319 for (i = 0; i < next; i++) {
320 if (!mcelog.entry[i].finished)
323 err |= copy_to_user(buf, mcelog.entry + i, sizeof(struct mce));
324 buf += sizeof(struct mce);
327 memset(mcelog.entry, 0, next * sizeof(struct mce));
331 synchronize_kernel();
333 /* Collect entries that were still getting written before the synchronize. */
335 on_each_cpu(collect_tscs, cpu_tsc, 1, 1);
336 for (i = next; i < MCE_LOG_LEN; i++) {
337 if (mcelog.entry[i].finished &&
338 mcelog.entry[i].tsc < cpu_tsc[mcelog.entry[i].cpu]) {
339 err |= copy_to_user(buf, mcelog.entry+i, sizeof(struct mce));
341 buf += sizeof(struct mce);
342 memset(&mcelog.entry[i], 0, sizeof(struct mce));
346 return err ? -EFAULT : buf - ubuf;
349 static int mce_ioctl(struct inode *i, struct file *f,unsigned int cmd, unsigned long arg)
351 if (!capable(CAP_SYS_ADMIN))
354 case MCE_GET_RECORD_LEN:
355 return put_user(sizeof(struct mce), (int *)arg);
356 case MCE_GET_LOG_LEN:
357 return put_user(MCE_LOG_LEN, (int *)arg);
358 case MCE_GETCLEAR_FLAGS: {
361 flags = mcelog.flags;
362 } while (cmpxchg(&mcelog.flags, flags, 0) != flags);
363 return put_user(flags, (int *)arg);
370 static struct file_operations mce_chrdev_ops = {
375 static struct miscdevice mce_log_device = {
382 * Old style boot options parsing. Only for compatibility.
385 static int __init mcheck_disable(char *str)
391 /* mce=off disable machine check */
392 static int __init mcheck_enable(char *str)
394 if (!strcmp(str, "off"))
397 printk("mce= argument %s ignored. Please use /sys", str);
401 __setup("nomce", mcheck_disable);
402 __setup("mce", mcheck_enable);
408 /* On resume clear all MCE state. Don't want to see leftovers from the BIOS. */
409 static int mce_resume(struct sys_device *dev)
412 on_each_cpu(mce_init, NULL, 1, 1);
416 /* Reinit MCEs after user configuration changes */
417 static void mce_restart(void)
420 cancel_delayed_work(&mcheck_work);
421 /* Timer race is harmless here */
422 on_each_cpu(mce_init, NULL, 1, 1);
424 schedule_delayed_work(&mcheck_work, check_interval*HZ);
427 static struct sysdev_class mce_sysclass = {
428 .resume = mce_resume,
429 set_kset_name("machinecheck"),
432 static struct sys_device device_mce = {
434 .cls = &mce_sysclass,
437 /* Why are there no generic functions for this? */
438 #define ACCESSOR(name, var, start) \
439 static ssize_t show_ ## name(struct sys_device *s, char *buf) { \
440 return sprintf(buf, "%lu\n", (unsigned long)var); \
442 static ssize_t set_ ## name(struct sys_device *s,const char *buf,size_t siz) { \
444 unsigned long new = simple_strtoul(buf, &end, 0); \
445 if (end == buf) return -EINVAL; \
450 static SYSDEV_ATTR(name, 0644, show_ ## name, set_ ## name);
452 ACCESSOR(bank0ctl,bank[0],mce_restart())
453 ACCESSOR(bank1ctl,bank[1],mce_restart())
454 ACCESSOR(bank2ctl,bank[2],mce_restart())
455 ACCESSOR(bank3ctl,bank[3],mce_restart())
456 ACCESSOR(bank4ctl,bank[4],mce_restart())
457 ACCESSOR(tolerant,tolerant,)
458 ACCESSOR(check_interval,check_interval,mce_restart())
460 static __init int mce_init_device(void)
463 if (!mce_available(&boot_cpu_data))
465 err = sysdev_class_register(&mce_sysclass);
467 err = sysdev_register(&device_mce);
469 /* could create per CPU objects, but is not worth it. */
470 sysdev_create_file(&device_mce, &attr_bank0ctl);
471 sysdev_create_file(&device_mce, &attr_bank1ctl);
472 sysdev_create_file(&device_mce, &attr_bank2ctl);
473 sysdev_create_file(&device_mce, &attr_bank3ctl);
474 sysdev_create_file(&device_mce, &attr_bank4ctl);
475 sysdev_create_file(&device_mce, &attr_tolerant);
476 sysdev_create_file(&device_mce, &attr_check_interval);
479 misc_register(&mce_log_device);
483 device_initcall(mce_init_device);