diff options
| -rw-r--r-- | Documentation/x86_64/machinecheck | 70 | ||||
| -rw-r--r-- | arch/x86_64/kernel/mce.c | 66 | ||||
| -rw-r--r-- | arch/x86_64/kernel/mce_amd.c | 4 | ||||
| -rw-r--r-- | include/asm-x86_64/mce.h | 2 | ||||
| -rw-r--r-- | kernel/kmod.c | 44 |
5 files changed, 160 insertions, 26 deletions
diff --git a/Documentation/x86_64/machinecheck b/Documentation/x86_64/machinecheck new file mode 100644 index 0000000..068a6d9 --- /dev/null +++ b/Documentation/x86_64/machinecheck @@ -0,0 +1,70 @@ + +Configurable sysfs parameters for the x86-64 machine check code. + +Machine checks report internal hardware error conditions detected +by the CPU. Uncorrected errors typically cause a machine check +(often with panic), corrected ones cause a machine check log entry. + +Machine checks are organized in banks (normally associated with +a hardware subsystem) and subevents in a bank. The exact meaning +of the banks and subevent is CPU specific. + +mcelog knows how to decode them. + +When you see the "Machine check errors logged" message in the system +log then mcelog should run to collect and decode machine check entries +from /dev/mcelog. Normally mcelog should be run regularly from a cronjob. + +Each CPU has a directory in /sys/devices/system/machinecheck/machinecheckN +(N = CPU number) + +The directory contains some configurable entries: + +Entries: + +bankNctl +(N bank number) + 64bit Hex bitmask enabling/disabling specific subevents for bank N + When a bit in the bitmask is zero then the respective + subevent will not be reported. + By default all events are enabled. + Note that BIOS maintain another mask to disable specific events + per bank. This is not visible here + +The following entries appear for each CPU, but they are truly shared +between all CPUs. + +check_interval + How often to poll for corrected machine check errors, in seconds + (Note output is hexademical). Default 5 minutes. + +tolerant + Tolerance level. When a machine check exception occurs for a non + corrected machine check the kernel can take different actions. + Since machine check exceptions can happen any time it is sometimes + risky for the kernel to kill a process because it defies + normal kernel locking rules. The tolerance level configures + how hard the kernel tries to recover even at some risk of deadlock. + + 0: always panic, + 1: panic if deadlock possible, + 2: try to avoid panic, + 3: never panic or exit (for testing only) + + Default: 1 + + Note this only makes a difference if the CPU allows recovery + from a machine check exception. Current x86 CPUs generally do not. + +trigger + Program to run when a machine check event is detected. + This is an alternative to running mcelog regularly from cron + and allows to detect events faster. + +TBD document entries for AMD threshold interrupt configuration + +For more details about the x86 machine check architecture +see the Intel and AMD architecture manuals from their developer websites. + +For more details about the architecture see +see http://one.firstfloor.org/~andi/mce.pdf diff --git a/arch/x86_64/kernel/mce.c b/arch/x86_64/kernel/mce.c index bdb54a2..8011a8e 100644 --- a/arch/x86_64/kernel/mce.c +++ b/arch/x86_64/kernel/mce.c @@ -19,6 +19,7 @@ #include <linux/cpu.h> #include <linux/percpu.h> #include <linux/ctype.h> +#include <linux/kmod.h> #include <asm/processor.h> #include <asm/msr.h> #include <asm/mce.h> @@ -42,6 +43,10 @@ static unsigned long console_logged; static int notify_user; static int rip_msr; static int mce_bootlog = 1; +static atomic_t mce_events; + +static char trigger[128]; +static char *trigger_argv[2] = { trigger, NULL }; /* * Lockless MCE logging infrastructure. @@ -57,6 +62,7 @@ struct mce_log mcelog = { void mce_log(struct mce *mce) { unsigned next, entry; + atomic_inc(&mce_events); mce->finished = 0; wmb(); for (;;) { @@ -161,6 +167,17 @@ static inline void mce_get_rip(struct mce *m, struct pt_regs *regs) } } +static void do_mce_trigger(void) +{ + static atomic_t mce_logged; + int events = atomic_read(&mce_events); + if (events != atomic_read(&mce_logged) && trigger[0]) { + /* Small race window, but should be harmless. */ + atomic_set(&mce_logged, events); + call_usermodehelper(trigger, trigger_argv, NULL, -1); + } +} + /* * The actual machine check handler */ @@ -234,8 +251,12 @@ void do_machine_check(struct pt_regs * regs, long error_code) } /* Never do anything final in the polling timer */ - if (!regs) + if (!regs) { + /* Normal interrupt context here. Call trigger for any new + events. */ + do_mce_trigger(); goto out; + } /* If we didn't find an uncorrectable error, pick the last one (shouldn't happen, just being safe). */ @@ -606,17 +627,42 @@ DEFINE_PER_CPU(struct sys_device, device_mce); } \ static SYSDEV_ATTR(name, 0644, show_ ## name, set_ ## name); +/* TBD should generate these dynamically based on number of available banks */ 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(bank5ctl,bank[5],mce_restart()) -static struct sysdev_attribute * bank_attributes[NR_BANKS] = { - &attr_bank0ctl, &attr_bank1ctl, &attr_bank2ctl, - &attr_bank3ctl, &attr_bank4ctl, &attr_bank5ctl}; + +static ssize_t show_trigger(struct sys_device *s, char *buf) +{ + strcpy(buf, trigger); + strcat(buf, "\n"); + return strlen(trigger) + 1; +} + +static ssize_t set_trigger(struct sys_device *s,const char *buf,size_t siz) +{ + char *p; + int len; + strncpy(trigger, buf, sizeof(trigger)); + trigger[sizeof(trigger)-1] = 0; + len = strlen(trigger); + p = strchr(trigger, '\n'); + if (*p) *p = 0; + return len; +} + +static SYSDEV_ATTR(trigger, 0644, show_trigger, set_trigger); ACCESSOR(tolerant,tolerant,) ACCESSOR(check_interval,check_interval,mce_restart()) +static struct sysdev_attribute *mce_attributes[] = { + &attr_bank0ctl, &attr_bank1ctl, &attr_bank2ctl, + &attr_bank3ctl, &attr_bank4ctl, &attr_bank5ctl, + &attr_tolerant, &attr_check_interval, &attr_trigger, + NULL +}; /* Per cpu sysdev init. All of the cpus still share the same ctl bank */ static __cpuinit int mce_create_device(unsigned int cpu) @@ -632,11 +678,9 @@ static __cpuinit int mce_create_device(unsigned int cpu) err = sysdev_register(&per_cpu(device_mce,cpu)); if (!err) { - for (i = 0; i < banks; i++) + for (i = 0; mce_attributes[i]; i++) sysdev_create_file(&per_cpu(device_mce,cpu), - bank_attributes[i]); - sysdev_create_file(&per_cpu(device_mce,cpu), &attr_tolerant); - sysdev_create_file(&per_cpu(device_mce,cpu), &attr_check_interval); + mce_attributes[i]); } return err; } @@ -645,11 +689,9 @@ static void mce_remove_device(unsigned int cpu) { int i; - for (i = 0; i < banks; i++) + for (i = 0; mce_attributes[i]; i++) sysdev_remove_file(&per_cpu(device_mce,cpu), - bank_attributes[i]); - sysdev_remove_file(&per_cpu(device_mce,cpu), &attr_tolerant); - sysdev_remove_file(&per_cpu(device_mce,cpu), &attr_check_interval); + mce_attributes[i]); sysdev_unregister(&per_cpu(device_mce,cpu)); memset(&per_cpu(device_mce, cpu).kobj, 0, sizeof(struct kobject)); } diff --git a/arch/x86_64/kernel/mce_amd.c b/arch/x86_64/kernel/mce_amd.c index cd8dbe5..d0bd5d6 100644 --- a/arch/x86_64/kernel/mce_amd.c +++ b/arch/x86_64/kernel/mce_amd.c @@ -220,6 +220,10 @@ asmlinkage void mce_threshold_interrupt(void) (high & MASK_LOCKED_HI)) continue; + /* Log the machine check that caused the threshold + event. */ + do_machine_check(NULL, 0); + if (high & MASK_OVERFLOW_HI) { rdmsrl(address, m.misc); rdmsrl(MSR_IA32_MC0_STATUS + bank * 4, diff --git a/include/asm-x86_64/mce.h b/include/asm-x86_64/mce.h index 5a11146..177e92b 100644 --- a/include/asm-x86_64/mce.h +++ b/include/asm-x86_64/mce.h @@ -103,6 +103,8 @@ void mce_log_therm_throt_event(unsigned int cpu, __u64 status); extern atomic_t mce_entry; +extern void do_machine_check(struct pt_regs *, long); + #endif #endif diff --git a/kernel/kmod.c b/kernel/kmod.c index 3a7379a..7962761 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -217,7 +217,10 @@ static int wait_for_helper(void *data) sub_info->retval = ret; } - complete(sub_info->complete); + if (sub_info->wait < 0) + kfree(sub_info); + else + complete(sub_info->complete); return 0; } @@ -239,6 +242,9 @@ static void __call_usermodehelper(struct work_struct *work) pid = kernel_thread(____call_usermodehelper, sub_info, CLONE_VFORK | SIGCHLD); + if (wait < 0) + return; + if (pid < 0) { sub_info->retval = pid; complete(sub_info->complete); @@ -253,6 +259,9 @@ static void __call_usermodehelper(struct work_struct *work) * @envp: null-terminated environment list * @session_keyring: session keyring for process (NULL for an empty keyring) * @wait: wait for the application to finish and return status. + * when -1 don't wait at all, but you get no useful error back when + * the program couldn't be exec'ed. This makes it safe to call + * from interrupt context. * * Runs a user-space application. The application is started * asynchronously if wait is not set, and runs as a child of keventd. @@ -265,17 +274,8 @@ int call_usermodehelper_keys(char *path, char **argv, char **envp, struct key *session_keyring, int wait) { DECLARE_COMPLETION_ONSTACK(done); - struct subprocess_info sub_info = { - .work = __WORK_INITIALIZER(sub_info.work, - __call_usermodehelper), - .complete = &done, - .path = path, - .argv = argv, - .envp = envp, - .ring = session_keyring, - .wait = wait, - .retval = 0, - }; + struct subprocess_info *sub_info; + int retval; if (!khelper_wq) return -EBUSY; @@ -283,9 +283,25 @@ int call_usermodehelper_keys(char *path, char **argv, char **envp, if (path[0] == '\0') return 0; - queue_work(khelper_wq, &sub_info.work); + sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC); + if (!sub_info) + return -ENOMEM; + + INIT_WORK(&sub_info->work, __call_usermodehelper); + sub_info->complete = &done; + sub_info->path = path; + sub_info->argv = argv; + sub_info->envp = envp; + sub_info->ring = session_keyring; + sub_info->wait = wait; + + queue_work(khelper_wq, &sub_info->work); + if (wait < 0) /* task has freed sub_info */ + return 0; wait_for_completion(&done); - return sub_info.retval; + retval = sub_info->retval; + kfree(sub_info); + return retval; } EXPORT_SYMBOL(call_usermodehelper_keys); |
