arch/ppc64/kernel/ras.c - kernel/msm-4.19 - Gitiles

 /*
  * ras.c
  * Copyright (C) 2001 Dave Engebretsen IBM Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  */

 /* Change Activity:
  * 2001/09/21 : engebret : Created with minimal EPOW and HW exception support.
  * End Change Activity
  */

 #include <linux/errno.h>
 #include <linux/threads.h>
 #include <linux/kernel_stat.h>
 #include <linux/signal.h>
 #include <linux/sched.h>
 #include <linux/ioport.h>
 #include <linux/interrupt.h>
 #include <linux/timex.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/pci.h>
 #include <linux/delay.h>
 #include <linux/irq.h>
 #include <linux/random.h>
 #include <linux/sysrq.h>
 #include <linux/bitops.h>

 #include <asm/uaccess.h>
 #include <asm/system.h>
 #include <asm/io.h>
 #include <asm/pgtable.h>
 #include <asm/irq.h>
 #include <asm/cache.h>
 #include <asm/prom.h>
 #include <asm/ptrace.h>
 #include <asm/machdep.h>
 #include <asm/rtas.h>
 #include <asm/ppcdebug.h>

 static unsigned char ras_log_buf[RTAS_ERROR_LOG_MAX];
 static DEFINE_SPINLOCK(ras_log_buf_lock);

 char mce_data_buf[RTAS_ERROR_LOG_MAX]
 ;
 /* This is true if we are using the firmware NMI handler (typically LPAR) */
 extern int fwnmi_active;

 static int ras_get_sensor_state_token;
 static int ras_check_exception_token;

 #define EPOW_SENSOR_TOKEN	9
 #define EPOW_SENSOR_INDEX	0
 #define RAS_VECTOR_OFFSET	0x500

 static irqreturn_t ras_epow_interrupt(int irq, void *dev_id,
 					struct pt_regs * regs);
 static irqreturn_t ras_error_interrupt(int irq, void *dev_id,
 					struct pt_regs * regs);

 /* #define DEBUG */

 static void request_ras_irqs(struct device_node *np, char *propname,
 			irqreturn_t (*handler)(int, void *, struct pt_regs *),
 			const char *name)
 {
 	unsigned int *ireg, len, i;
 	int virq, n_intr;

 	ireg = (unsigned int *)get_property(np, propname, &len);
 	if (ireg == NULL)
 		return;
 	n_intr = prom_n_intr_cells(np);
 	len /= n_intr * sizeof(*ireg);

 	for (i = 0; i < len; i++) {
 		virq = virt_irq_create_mapping(*ireg);
 		if (virq == NO_IRQ) {
 			printk(KERN_ERR "Unable to allocate interrupt "
 			       "number for %s\n", np->full_name);
 			return;
 		}
 		if (request_irq(irq_offset_up(virq), handler, 0, name, NULL)) {
 			printk(KERN_ERR "Unable to request interrupt %d for "
 			       "%s\n", irq_offset_up(virq), np->full_name);
 			return;
 		}
 		ireg += n_intr;
 	}
 }

 /*
  * Initialize handlers for the set of interrupts caused by hardware errors
  * and power system events.
  */
 static int __init init_ras_IRQ(void)
 {
 	struct device_node *np;

 	ras_get_sensor_state_token = rtas_token("get-sensor-state");
 	ras_check_exception_token = rtas_token("check-exception");

 	/* Internal Errors */
 	np = of_find_node_by_path("/event-sources/internal-errors");
 	if (np != NULL) {
 		request_ras_irqs(np, "open-pic-interrupt", ras_error_interrupt,
 				 "RAS_ERROR");
 		request_ras_irqs(np, "interrupts", ras_error_interrupt,
 				 "RAS_ERROR");
 		of_node_put(np);
 	}

 	/* EPOW Events */
 	np = of_find_node_by_path("/event-sources/epow-events");
 	if (np != NULL) {
 		request_ras_irqs(np, "open-pic-interrupt", ras_epow_interrupt,
 				 "RAS_EPOW");
 		request_ras_irqs(np, "interrupts", ras_epow_interrupt,
 				 "RAS_EPOW");
 		of_node_put(np);
 	}

 	return 1;
 }
 __initcall(init_ras_IRQ);

 /*
  * Handle power subsystem events (EPOW).
  *
  * Presently we just log the event has occurred.  This should be fixed
  * to examine the type of power failure and take appropriate action where
  * the time horizon permits something useful to be done.
  */
 static irqreturn_t
 ras_epow_interrupt(int irq, void *dev_id, struct pt_regs * regs)
 {
 	int status = 0xdeadbeef;
 	int state = 0;
 	int critical;

 	status = rtas_call(ras_get_sensor_state_token, 2, 2, &state,
 			   EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX);

 	if (state > 3)
 		critical = 1;  /* Time Critical */
 	else
 		critical = 0;

 	spin_lock(&ras_log_buf_lock);

 	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
 			   RAS_VECTOR_OFFSET,
 			   virt_irq_to_real(irq_offset_down(irq)),
 			   RTAS_EPOW_WARNING | RTAS_POWERMGM_EVENTS,
 			   critical, __pa(&ras_log_buf),
 				rtas_get_error_log_max());

 	udbg_printf("EPOW <0x%lx 0x%x 0x%x>\n",
 		    *((unsigned long *)&ras_log_buf), status, state);
 	printk(KERN_WARNING "EPOW <0x%lx 0x%x 0x%x>\n",
 	       *((unsigned long *)&ras_log_buf), status, state);

 	/* format and print the extended information */
 	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0);

 	spin_unlock(&ras_log_buf_lock);
 	return IRQ_HANDLED;
 }

 /*
  * Handle hardware error interrupts.
  *
  * RTAS check-exception is called to collect data on the exception.  If
  * the error is deemed recoverable, we log a warning and return.
  * For nonrecoverable errors, an error is logged and we stop all processing
  * as quickly as possible in order to prevent propagation of the failure.
  */
 static irqreturn_t
 ras_error_interrupt(int irq, void *dev_id, struct pt_regs * regs)
 {
 	struct rtas_error_log *rtas_elog;
 	int status = 0xdeadbeef;
 	int fatal;

 	spin_lock(&ras_log_buf_lock);

 	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
 			   RAS_VECTOR_OFFSET,
 			   virt_irq_to_real(irq_offset_down(irq)),
 			   RTAS_INTERNAL_ERROR, 1 /*Time Critical */,
 			   __pa(&ras_log_buf),
 				rtas_get_error_log_max());

 	rtas_elog = (struct rtas_error_log *)ras_log_buf;

 	if ((status == 0) && (rtas_elog->severity >= RTAS_SEVERITY_ERROR_SYNC))
 		fatal = 1;
 	else
 		fatal = 0;

 	/* format and print the extended information */
 	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, fatal);

 	if (fatal) {
 		udbg_printf("Fatal HW Error <0x%lx 0x%x>\n",
 			    *((unsigned long *)&ras_log_buf), status);
 		printk(KERN_EMERG "Error: Fatal hardware error <0x%lx 0x%x>\n",
 		       *((unsigned long *)&ras_log_buf), status);

 #ifndef DEBUG
 		/* Don't actually power off when debugging so we can test
 		 * without actually failing while injecting errors.
 		 * Error data will not be logged to syslog.
 		 */
 		ppc_md.power_off();
 #endif
 	} else {
 		udbg_printf("Recoverable HW Error <0x%lx 0x%x>\n",
 			    *((unsigned long *)&ras_log_buf), status);
 		printk(KERN_WARNING
 		       "Warning: Recoverable hardware error <0x%lx 0x%x>\n",
 		       *((unsigned long *)&ras_log_buf), status);
 	}

 	spin_unlock(&ras_log_buf_lock);
 	return IRQ_HANDLED;
 }

 /* Get the error information for errors coming through the
  * FWNMI vectors.  The pt_regs' r3 will be updated to reflect
  * the actual r3 if possible, and a ptr to the error log entry
  * will be returned if found.
  *
  * The mce_data_buf does not have any locks or protection around it,
  * if a second machine check comes in, or a system reset is done
  * before we have logged the error, then we will get corruption in the
  * error log.  This is preferable over holding off on calling
  * ibm,nmi-interlock which would result in us checkstopping if a
  * second machine check did come in.
  */
 static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
 {
 	unsigned long errdata = regs->gpr[3];
 	struct rtas_error_log *errhdr = NULL;
 	unsigned long *savep;

 	if ((errdata >= 0x7000 && errdata < 0x7fff0) ||
 	    (errdata >= rtas.base && errdata < rtas.base + rtas.size - 16)) {
 		savep = __va(errdata);
 		regs->gpr[3] = savep[0];	/* restore original r3 */
 		memset(mce_data_buf, 0, RTAS_ERROR_LOG_MAX);
 		memcpy(mce_data_buf, (char *)(savep + 1), RTAS_ERROR_LOG_MAX);
 		errhdr = (struct rtas_error_log *)mce_data_buf;
 	} else {
 		printk("FWNMI: corrupt r3\n");
 	}
 	return errhdr;
 }

 /* Call this when done with the data returned by FWNMI_get_errinfo.
  * It will release the saved data area for other CPUs in the
  * partition to receive FWNMI errors.
  */
 static void fwnmi_release_errinfo(void)
 {
 	int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
 	if (ret != 0)
 		printk("FWNMI: nmi-interlock failed: %d\n", ret);
 }

 void pSeries_system_reset_exception(struct pt_regs *regs)
 {
 	if (fwnmi_active) {
 		struct rtas_error_log *errhdr = fwnmi_get_errinfo(regs);
 		if (errhdr) {
 			/* XXX Should look at FWNMI information */
 		}
 		fwnmi_release_errinfo();
 	}
 }

 /*
  * See if we can recover from a machine check exception.
  * This is only called on power4 (or above) and only via
  * the Firmware Non-Maskable Interrupts (fwnmi) handler
  * which provides the error analysis for us.
  *
  * Return 1 if corrected (or delivered a signal).
  * Return 0 if there is nothing we can do.
  */
 static int recover_mce(struct pt_regs *regs, struct rtas_error_log * err)
 {
 	int nonfatal = 0;

 	if (err->disposition == RTAS_DISP_FULLY_RECOVERED) {
 		/* Platform corrected itself */
 		nonfatal = 1;
 	} else if ((regs->msr & MSR_RI) &&
 		   user_mode(regs) &&
 		   err->severity == RTAS_SEVERITY_ERROR_SYNC &&
 		   err->disposition == RTAS_DISP_NOT_RECOVERED &&
 		   err->target == RTAS_TARGET_MEMORY &&
 		   err->type == RTAS_TYPE_ECC_UNCORR &&
 		   !(current->pid == 0 || current->pid == 1)) {
 		/* Kill off a user process with an ECC error */
 		printk(KERN_ERR "MCE: uncorrectable ecc error for pid %d\n",
 		       current->pid);
 		/* XXX something better for ECC error? */
 		_exception(SIGBUS, regs, BUS_ADRERR, regs->nip);
 		nonfatal = 1;
 	}

  	log_error((char *)err, ERR_TYPE_RTAS_LOG, !nonfatal);

 	return nonfatal;
 }

 /*
  * Handle a machine check.
  *
  * Note that on Power 4 and beyond Firmware Non-Maskable Interrupts (fwnmi)
  * should be present.  If so the handler which called us tells us if the
  * error was recovered (never true if RI=0).
  *
  * On hardware prior to Power 4 these exceptions were asynchronous which
  * means we can't tell exactly where it occurred and so we can't recover.
  */
 int pSeries_machine_check_exception(struct pt_regs *regs)
 {
 	struct rtas_error_log *errp;

 	if (fwnmi_active) {
 		errp = fwnmi_get_errinfo(regs);
 		fwnmi_release_errinfo();
 		if (errp && recover_mce(regs, errp))
 			return 1;
 	}

 	return 0;
 }
	/*
	* ras.c
	* Copyright (C) 2001 Dave Engebretsen IBM Corporation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/

	/* Change Activity:
	* 2001/09/21 : engebret : Created with minimal EPOW and HW exception support.
	* End Change Activity
	*/

	#include <linux/errno.h>
	#include <linux/threads.h>
	#include <linux/kernel_stat.h>
	#include <linux/signal.h>
	#include <linux/sched.h>
	#include <linux/ioport.h>
	#include <linux/interrupt.h>
	#include <linux/timex.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/pci.h>
	#include <linux/delay.h>
	#include <linux/irq.h>
	#include <linux/random.h>
	#include <linux/sysrq.h>
	#include <linux/bitops.h>

	#include <asm/uaccess.h>
	#include <asm/system.h>
	#include <asm/io.h>
	#include <asm/pgtable.h>
	#include <asm/irq.h>
	#include <asm/cache.h>
	#include <asm/prom.h>
	#include <asm/ptrace.h>
	#include <asm/machdep.h>
	#include <asm/rtas.h>
	#include <asm/ppcdebug.h>

	static unsigned char ras_log_buf[RTAS_ERROR_LOG_MAX];
	static DEFINE_SPINLOCK(ras_log_buf_lock);

	char mce_data_buf[RTAS_ERROR_LOG_MAX]
	;
	/* This is true if we are using the firmware NMI handler (typically LPAR) */
	extern int fwnmi_active;

	static int ras_get_sensor_state_token;
	static int ras_check_exception_token;

	#define EPOW_SENSOR_TOKEN 9
	#define EPOW_SENSOR_INDEX 0
	#define RAS_VECTOR_OFFSET 0x500

	static irqreturn_t ras_epow_interrupt(int irq, void *dev_id,
	struct pt_regs * regs);
	static irqreturn_t ras_error_interrupt(int irq, void *dev_id,
	struct pt_regs * regs);

	/* #define DEBUG */

	static void request_ras_irqs(struct device_node np, char propname,
	irqreturn_t (handler)(int, void , struct pt_regs *),
	const char *name)
	{
	unsigned int *ireg, len, i;
	int virq, n_intr;

	ireg = (unsigned int *)get_property(np, propname, &len);
	if (ireg == NULL)
	return;
	n_intr = prom_n_intr_cells(np);
	len /= n_intr * sizeof(*ireg);

	for (i = 0; i < len; i++) {
	virq = virt_irq_create_mapping(*ireg);
	if (virq == NO_IRQ) {
	printk(KERN_ERR "Unable to allocate interrupt "
	"number for %s\n", np->full_name);
	return;
	}
	if (request_irq(irq_offset_up(virq), handler, 0, name, NULL)) {
	printk(KERN_ERR "Unable to request interrupt %d for "
	"%s\n", irq_offset_up(virq), np->full_name);
	return;
	}
	ireg += n_intr;
	}
	}

	/*
	* Initialize handlers for the set of interrupts caused by hardware errors
	* and power system events.
	*/
	static int __init init_ras_IRQ(void)
	{
	struct device_node *np;

	ras_get_sensor_state_token = rtas_token("get-sensor-state");
	ras_check_exception_token = rtas_token("check-exception");

	/* Internal Errors */
	np = of_find_node_by_path("/event-sources/internal-errors");
	if (np != NULL) {
	request_ras_irqs(np, "open-pic-interrupt", ras_error_interrupt,
	"RAS_ERROR");
	request_ras_irqs(np, "interrupts", ras_error_interrupt,
	"RAS_ERROR");
	of_node_put(np);
	}

	/* EPOW Events */
	np = of_find_node_by_path("/event-sources/epow-events");
	if (np != NULL) {
	request_ras_irqs(np, "open-pic-interrupt", ras_epow_interrupt,
	"RAS_EPOW");
	request_ras_irqs(np, "interrupts", ras_epow_interrupt,
	"RAS_EPOW");
	of_node_put(np);
	}

	return 1;
	}
	__initcall(init_ras_IRQ);

	/*
	* Handle power subsystem events (EPOW).
	*
	* Presently we just log the event has occurred. This should be fixed
	* to examine the type of power failure and take appropriate action where
	* the time horizon permits something useful to be done.
	*/
	static irqreturn_t
	ras_epow_interrupt(int irq, void dev_id, struct pt_regs regs)
	{
	int status = 0xdeadbeef;
	int state = 0;
	int critical;

	status = rtas_call(ras_get_sensor_state_token, 2, 2, &state,
	EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX);

	if (state > 3)
	critical = 1; /* Time Critical */
	else
	critical = 0;

	spin_lock(&ras_log_buf_lock);

	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
	RAS_VECTOR_OFFSET,
	virt_irq_to_real(irq_offset_down(irq)),
	RTAS_EPOW_WARNING \| RTAS_POWERMGM_EVENTS,
	critical, __pa(&ras_log_buf),
	rtas_get_error_log_max());

	udbg_printf("EPOW <0x%lx 0x%x 0x%x>\n",
	((unsigned long )&ras_log_buf), status, state);
	printk(KERN_WARNING "EPOW <0x%lx 0x%x 0x%x>\n",
	((unsigned long )&ras_log_buf), status, state);

	/* format and print the extended information */
	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0);

	spin_unlock(&ras_log_buf_lock);
	return IRQ_HANDLED;
	}

	/*
	* Handle hardware error interrupts.
	*
	* RTAS check-exception is called to collect data on the exception. If
	* the error is deemed recoverable, we log a warning and return.
	* For nonrecoverable errors, an error is logged and we stop all processing
	* as quickly as possible in order to prevent propagation of the failure.
	*/
	static irqreturn_t
	ras_error_interrupt(int irq, void dev_id, struct pt_regs regs)
	{
	struct rtas_error_log *rtas_elog;
	int status = 0xdeadbeef;
	int fatal;

	spin_lock(&ras_log_buf_lock);

	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
	RAS_VECTOR_OFFSET,
	virt_irq_to_real(irq_offset_down(irq)),
	RTAS_INTERNAL_ERROR, 1 /Time Critical /,
	__pa(&ras_log_buf),
	rtas_get_error_log_max());

	rtas_elog = (struct rtas_error_log *)ras_log_buf;

	if ((status == 0) && (rtas_elog->severity >= RTAS_SEVERITY_ERROR_SYNC))
	fatal = 1;
	else
	fatal = 0;

	/* format and print the extended information */
	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, fatal);

	if (fatal) {
	udbg_printf("Fatal HW Error <0x%lx 0x%x>\n",
	((unsigned long )&ras_log_buf), status);
	printk(KERN_EMERG "Error: Fatal hardware error <0x%lx 0x%x>\n",
	((unsigned long )&ras_log_buf), status);

	#ifndef DEBUG
	/* Don't actually power off when debugging so we can test
	* without actually failing while injecting errors.
	* Error data will not be logged to syslog.
	*/
	ppc_md.power_off();
	#endif
	} else {
	udbg_printf("Recoverable HW Error <0x%lx 0x%x>\n",
	((unsigned long )&ras_log_buf), status);
	printk(KERN_WARNING
	"Warning: Recoverable hardware error <0x%lx 0x%x>\n",
	((unsigned long )&ras_log_buf), status);
	}

	spin_unlock(&ras_log_buf_lock);
	return IRQ_HANDLED;
	}

	/* Get the error information for errors coming through the
	* FWNMI vectors. The pt_regs' r3 will be updated to reflect
	* the actual r3 if possible, and a ptr to the error log entry
	* will be returned if found.
	*
	* The mce_data_buf does not have any locks or protection around it,
	* if a second machine check comes in, or a system reset is done
	* before we have logged the error, then we will get corruption in the
	* error log. This is preferable over holding off on calling
	* ibm,nmi-interlock which would result in us checkstopping if a
	* second machine check did come in.
	*/
	static struct rtas_error_log fwnmi_get_errinfo(struct pt_regs regs)
	{
	unsigned long errdata = regs->gpr[3];
	struct rtas_error_log *errhdr = NULL;
	unsigned long *savep;

	if ((errdata >= 0x7000 && errdata < 0x7fff0) \|\|
	(errdata >= rtas.base && errdata < rtas.base + rtas.size - 16)) {
	savep = __va(errdata);
	regs->gpr[3] = savep[0]; /* restore original r3 */
	memset(mce_data_buf, 0, RTAS_ERROR_LOG_MAX);
	memcpy(mce_data_buf, (char *)(savep + 1), RTAS_ERROR_LOG_MAX);
	errhdr = (struct rtas_error_log *)mce_data_buf;
	} else {
	printk("FWNMI: corrupt r3\n");
	}
	return errhdr;
	}

	/* Call this when done with the data returned by FWNMI_get_errinfo.
	* It will release the saved data area for other CPUs in the
	* partition to receive FWNMI errors.
	*/
	static void fwnmi_release_errinfo(void)
	{
	int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
	if (ret != 0)
	printk("FWNMI: nmi-interlock failed: %d\n", ret);
	}

	void pSeries_system_reset_exception(struct pt_regs *regs)
	{
	if (fwnmi_active) {
	struct rtas_error_log *errhdr = fwnmi_get_errinfo(regs);
	if (errhdr) {
	/* XXX Should look at FWNMI information */
	}
	fwnmi_release_errinfo();
	}
	}

	/*
	* See if we can recover from a machine check exception.
	* This is only called on power4 (or above) and only via
	* the Firmware Non-Maskable Interrupts (fwnmi) handler
	* which provides the error analysis for us.
	*
	* Return 1 if corrected (or delivered a signal).
	* Return 0 if there is nothing we can do.
	*/
	static int recover_mce(struct pt_regs regs, struct rtas_error_log err)
	{
	int nonfatal = 0;

	if (err->disposition == RTAS_DISP_FULLY_RECOVERED) {
	/* Platform corrected itself */
	nonfatal = 1;
	} else if ((regs->msr & MSR_RI) &&
	user_mode(regs) &&
	err->severity == RTAS_SEVERITY_ERROR_SYNC &&
	err->disposition == RTAS_DISP_NOT_RECOVERED &&
	err->target == RTAS_TARGET_MEMORY &&
	err->type == RTAS_TYPE_ECC_UNCORR &&
	!(current->pid == 0 \|\| current->pid == 1)) {
	/* Kill off a user process with an ECC error */
	printk(KERN_ERR "MCE: uncorrectable ecc error for pid %d\n",
	current->pid);
	/* XXX something better for ECC error? */
	_exception(SIGBUS, regs, BUS_ADRERR, regs->nip);
	nonfatal = 1;
	}

	log_error((char *)err, ERR_TYPE_RTAS_LOG, !nonfatal);

	return nonfatal;
	}

	/*
	* Handle a machine check.
	*
	* Note that on Power 4 and beyond Firmware Non-Maskable Interrupts (fwnmi)
	* should be present. If so the handler which called us tells us if the
	* error was recovered (never true if RI=0).
	*
	* On hardware prior to Power 4 these exceptions were asynchronous which
	* means we can't tell exactly where it occurred and so we can't recover.
	*/
	int pSeries_machine_check_exception(struct pt_regs *regs)
	{
	struct rtas_error_log *errp;

	if (fwnmi_active) {
	errp = fwnmi_get_errinfo(regs);
	fwnmi_release_errinfo();
	if (errp && recover_mce(regs, errp))
	return 1;
	}

	return 0;
	}