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Commit cd9c57ca authored by Borislav Petkov's avatar Borislav Petkov Committed by Thomas Gleixner
Browse files

x86/MCE: Dump MCE to dmesg if no consumers 



When there are no error record consumers registered with the kernel, the
only thing that appears in dmesg is something like:

  [  300.000326] mce: [Hardware Error]: Machine check events logged

and the error records are gone. Which is seriously counterproductive.

So let's dump them to dmesg instead, in such a case.

Requested-by: default avatarEric Morton <Eric.Morton@amd.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/20161101120911.13163-4-bp@alien8.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 8c203dbb

arch/x86/kernel/cpu/mcheck/mce.c

+46 −6
Original line number Diff line number Diff line
@@ -207,8 +207,12 @@ EXPORT_SYMBOL_GPL(mce_inject_log); 


static struct notifier_block mce_srao_nb;



static atomic_t num_notifiers;



void mce_register_decode_chain(struct notifier_block *nb)

{

	atomic_inc(&num_notifiers);



	/* Ensure SRAO notifier has the highest priority in the decode chain. */

	if (nb != &mce_srao_nb && nb->priority == INT_MAX)

		nb->priority -= 1;
@@ -219,6 +223,8 @@ EXPORT_SYMBOL_GPL(mce_register_decode_chain); 


void mce_unregister_decode_chain(struct notifier_block *nb)

{

	atomic_dec(&num_notifiers);



	atomic_notifier_chain_unregister(&x86_mce_decoder_chain, nb);

}

EXPORT_SYMBOL_GPL(mce_unregister_decode_chain);
@@ -270,12 +276,12 @@ struct mca_msr_regs msr_ops = { 
	.misc	= misc_reg

};



static void print_mce(struct mce *m)

static void __print_mce(struct mce *m)

{

	int ret = 0;



	pr_emerg(HW_ERR "CPU %d: Machine Check Exception: %Lx Bank %d: %016Lx\n",

	       m->extcpu, m->mcgstatus, m->bank, m->status);

	pr_emerg(HW_ERR "CPU %d: Machine Check%s: %Lx Bank %d: %016Lx\n",

		 m->extcpu,

		 (m->mcgstatus & MCG_STATUS_MCIP ? " Exception" : ""),

		 m->mcgstatus, m->bank, m->status);



	if (m->ip) {

		pr_emerg(HW_ERR "RIP%s %02x:<%016Lx> ",
@@ -308,6 +314,13 @@ static void print_mce(struct mce *m) 
	pr_emerg(HW_ERR "PROCESSOR %u:%x TIME %llu SOCKET %u APIC %x microcode %x\n",

		m->cpuvendor, m->cpuid, m->time, m->socketid, m->apicid,

		cpu_data(m->extcpu).microcode);

}



static void print_mce(struct mce *m)

{

	int ret = 0;



	__print_mce(m);



	/*

	 * Print out human-readable details about the MCE error,
@@ -569,6 +582,32 @@ static struct notifier_block mce_srao_nb = { 
	.priority = INT_MAX,

};



static int mce_default_notifier(struct notifier_block *nb, unsigned long val,

				void *data)

{

	struct mce *m = (struct mce *)data;



	if (!m)

		return NOTIFY_DONE;



	/*

	 * Run the default notifier if we have only the SRAO

	 * notifier and us registered.

	 */

	if (atomic_read(&num_notifiers) > 2)

		return NOTIFY_DONE;



	__print_mce(m);



	return NOTIFY_DONE;

}



static struct notifier_block mce_default_nb = {

	.notifier_call	= mce_default_notifier,

	/* lowest prio, we want it to run last. */

	.priority	= 0,

};



/*

 * Read ADDR and MISC registers.

 */
@@ -2138,6 +2177,7 @@ int __init mcheck_init(void) 
{

	mcheck_intel_therm_init();

	mce_register_decode_chain(&mce_srao_nb);

	mce_register_decode_chain(&mce_default_nb);

	mcheck_vendor_init_severity();



	INIT_WORK(&mce_work, mce_process_work);