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Commit 4611a6fa authored by Huang Ying's avatar Huang Ying Committed by H. Peter Anvin
Browse files

x86, mce: export MCE severities coverage via debugfs 



The MCE severity judgement code is data-driven, so code coverage tools
such as gcov can not be used for measuring coverage. Instead a dedicated
coverage mechanism is implemented.  The kernel keeps track of rules
executed and reports them in debugfs.

This is useful for increasing coverage of the mce-test testsuite.

Right now it's unconditionally enabled because it's very little code.

Signed-off-by: default avatarHuang Ying <ying.huang@intel.com>
Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent ed7290d0

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

+83 −0
Original line number Diff line number Diff line
@@ -10,6 +10,9 @@ 
 * Author: Andi Kleen

 */

#include <linux/kernel.h>

#include <linux/seq_file.h>

#include <linux/init.h>

#include <linux/debugfs.h>

#include <asm/mce.h>



#include "mce-internal.h"
@@ -37,6 +40,7 @@ static struct severity { 
	unsigned char mcgres;

	unsigned char ser;

	unsigned char context;

	unsigned char covered;

	char *msg;

} severities[] = {

#define KERNEL .context = IN_KERNEL
@@ -126,6 +130,7 @@ int mce_severity(struct mce *a, int tolerant, char **msg) 
			continue;

		if (msg)

			*msg = s->msg;

		s->covered = 1;

		if (s->sev >= MCE_UC_SEVERITY && ctx == IN_KERNEL) {

			if (panic_on_oops || tolerant < 1)

				return MCE_PANIC_SEVERITY;
@@ -133,3 +138,81 @@ int mce_severity(struct mce *a, int tolerant, char **msg) 
		return s->sev;

	}

}



static void *s_start(struct seq_file *f, loff_t *pos)

{

	if (*pos >= ARRAY_SIZE(severities))

		return NULL;

	return &severities[*pos];

}



static void *s_next(struct seq_file *f, void *data, loff_t *pos)

{

	if (++(*pos) >= ARRAY_SIZE(severities))

		return NULL;

	return &severities[*pos];

}



static void s_stop(struct seq_file *f, void *data)

{

}



static int s_show(struct seq_file *f, void *data)

{

	struct severity *ser = data;

	seq_printf(f, "%d\t%s\n", ser->covered, ser->msg);

	return 0;

}



static const struct seq_operations severities_seq_ops = {

	.start	= s_start,

	.next	= s_next,

	.stop	= s_stop,

	.show	= s_show,

};



static int severities_coverage_open(struct inode *inode, struct file *file)

{

	return seq_open(file, &severities_seq_ops);

}



static ssize_t severities_coverage_write(struct file *file,

					 const char __user *ubuf,

					 size_t count, loff_t *ppos)

{

	int i;

	for (i = 0; i < ARRAY_SIZE(severities); i++)

		severities[i].covered = 0;

	return count;

}



static const struct file_operations severities_coverage_fops = {

	.open		= severities_coverage_open,

	.release	= seq_release,

	.read		= seq_read,

	.write		= severities_coverage_write,

};



static int __init severities_debugfs_init(void)

{

	struct dentry *dmce = NULL, *fseverities_coverage = NULL;



	dmce = debugfs_create_dir("mce", NULL);

	if (dmce == NULL)

		goto err_out;

	fseverities_coverage = debugfs_create_file("severities-coverage",

						   0444, dmce, NULL,

						   &severities_coverage_fops);

	if (fseverities_coverage == NULL)

		goto err_out;



	return 0;



err_out:

	if (fseverities_coverage)

		debugfs_remove(fseverities_coverage);

	if (dmce)

		debugfs_remove(dmce);

	return -ENOMEM;

}

late_initcall(severities_debugfs_init);