[PATCH] x86-64: Allow to run a program when a machine check event is detected (a98f0dd3) · Commits · 戴 / test

Documentation/x86_64/machinecheck

0 → 100644

+70 −0

Original line number	Diff line number	Diff line

		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

arch/x86_64/kernel/mce.c

+54 −12

Original line number	Diff line number	Diff line
		@@ -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));
		}

arch/x86_64/kernel/mce_amd.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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,

include/asm-x86_64/mce.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -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

kernel/kmod.c

+30 −14

Original line number	Diff line number	Diff line
		@@ -217,6 +217,9 @@ static int wait_for_helper(void *data)
		sub_info->retval = ret;
		}

		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);

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