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Commit af104e39 authored by Tony Luck's avatar Tony Luck
Browse files

x86/mce: Add mechanism to safely save information in MCE handler 



Machine checks on Intel cpus interrupt execution on all cpus, regardless
of interrupt masking.  We have a need to save some data about the cause
of the machine check (physical address) in the machine check handler that
can be retrieved later to attempt recovery in a more flexible execution
state.

Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 85f92694

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

+43 −0
Original line number Original line Diff line number Diff line
@@ -886,6 +886,49 @@ static void mce_clear_state(unsigned long *toclear) 
	}

	}

}

}





/*

 * Need to save faulting physical address associated with a process

 * in the machine check handler some place where we can grab it back

 * later in mce_notify_process()

 */

#define	MCE_INFO_MAX	16



struct mce_info {

	atomic_t		inuse;

	struct task_struct	*t;

	__u64			paddr;

} mce_info[MCE_INFO_MAX];



static void mce_save_info(__u64 addr)

{

	struct mce_info *mi;



	for (mi = mce_info; mi < &mce_info[MCE_INFO_MAX]; mi++) {

		if (atomic_cmpxchg(&mi->inuse, 0, 1) == 0) {

			mi->t = current;

			mi->paddr = addr;

			return;

		}

	}



	mce_panic("Too many concurrent recoverable errors", NULL, NULL);

}



static struct mce_info *mce_find_info(void)

{

	struct mce_info *mi;



	for (mi = mce_info; mi < &mce_info[MCE_INFO_MAX]; mi++)

		if (atomic_read(&mi->inuse) && mi->t == current)

			return mi;

	return NULL;

}



static void mce_clear_info(struct mce_info *mi)

{

	atomic_set(&mi->inuse, 0);

}



/*

/*

 * The actual machine check handler. This only handles real

 * The actual machine check handler. This only handles real

 * exceptions when something got corrupted coming in through int 18.

 * exceptions when something got corrupted coming in through int 18.