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Commit b63a0ffe authored by Mahesh Salgaonkar's avatar Mahesh Salgaonkar Committed by Benjamin Herrenschmidt
Browse files

powerpc/powernv: Machine check exception handling. 



Add basic error handling in machine check exception handler.

- If MSR_RI isn't set, we can not recover.
- Check if disposition set to OpalMCE_DISPOSITION_RECOVERED.
- Check if address at fault is inside kernel address space, if not then send
  SIGBUS to process if we hit exception when in userspace.
- If address at fault is not provided then and if we get a synchronous machine
  check while in userspace then kill the task.

Signed-off-by: default avatarMahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 28446de2

arch/powerpc/include/asm/mce.h

+1 −0
Original line number Diff line number Diff line
@@ -193,5 +193,6 @@ extern void release_mce_event(void); 
extern void machine_check_queue_event(void);

extern void machine_check_process_queued_event(void);

extern void machine_check_print_event_info(struct machine_check_event *evt);

extern uint64_t get_mce_fault_addr(struct machine_check_event *evt);



#endif /* __ASM_PPC64_MCE_H__ */

arch/powerpc/kernel/mce.c

+27 −0
Original line number Diff line number Diff line
@@ -316,3 +316,30 @@ void machine_check_print_event_info(struct machine_check_event *evt) 
		break;

	}

}



uint64_t get_mce_fault_addr(struct machine_check_event *evt)

{

	switch (evt->error_type) {

	case MCE_ERROR_TYPE_UE:

		if (evt->u.ue_error.effective_address_provided)

			return evt->u.ue_error.effective_address;

		break;

	case MCE_ERROR_TYPE_SLB:

		if (evt->u.slb_error.effective_address_provided)

			return evt->u.slb_error.effective_address;

		break;

	case MCE_ERROR_TYPE_ERAT:

		if (evt->u.erat_error.effective_address_provided)

			return evt->u.erat_error.effective_address;

		break;

	case MCE_ERROR_TYPE_TLB:

		if (evt->u.tlb_error.effective_address_provided)

			return evt->u.tlb_error.effective_address;

		break;

	default:

	case MCE_ERROR_TYPE_UNKNOWN:

		break;

	}

	return 0;

}

EXPORT_SYMBOL(get_mce_fault_addr);

arch/powerpc/platforms/powernv/opal.c

+42 −1
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/interrupt.h>

#include <linux/notifier.h>

#include <linux/slab.h>

#include <linux/sched.h>

#include <linux/kobject.h>

#include <asm/opal.h>

#include <asm/firmware.h>
@@ -251,6 +252,44 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) 
	return written;

}



static int opal_recover_mce(struct pt_regs *regs,

					struct machine_check_event *evt)

{

	int recovered = 0;

	uint64_t ea = get_mce_fault_addr(evt);



	if (!(regs->msr & MSR_RI)) {

		/* If MSR_RI isn't set, we cannot recover */

		recovered = 0;

	} else if (evt->disposition == MCE_DISPOSITION_RECOVERED) {

		/* Platform corrected itself */

		recovered = 1;

	} else if (ea && !is_kernel_addr(ea)) {

		/*

		 * Faulting address is not in kernel text. We should be fine.

		 * We need to find which process uses this address.

		 * For now, kill the task if we have received exception when

		 * in userspace.

		 *

		 * TODO: Queue up this address for hwpoisioning later.

		 */

		if (user_mode(regs) && !is_global_init(current)) {

			_exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);

			recovered = 1;

		} else

			recovered = 0;

	} else if (user_mode(regs) && !is_global_init(current) &&

		evt->severity == MCE_SEV_ERROR_SYNC) {

		/*

		 * If we have received a synchronous error when in userspace

		 * kill the task.

		 */

		_exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);

		recovered = 1;

	}

	return recovered;

}



int opal_machine_check(struct pt_regs *regs)

{

	struct machine_check_event evt;
@@ -266,7 +305,9 @@ int opal_machine_check(struct pt_regs *regs) 
	}

	machine_check_print_event_info(&evt);



	return evt.severity == MCE_SEV_FATAL ? 0 : 1;

	if (opal_recover_mce(regs, &evt))

		return 1;

	return 0;

}



static irqreturn_t opal_interrupt(int irq, void *data)