• Andi Kleen's avatar
    x86, mce: don't disable machine checks during code patching · 123aa76e
    Andi Kleen authored
    Impact: low priority bug fix
    
    This removes part of a a patch I added myself some time ago. After some
    consideration the patch was a bad idea. In particular it stopped machine check
    exceptions during code patching.
    
    To quote the comment:
    
            * MCEs only happen when something got corrupted and in this
            * case we must do something about the corruption.
            * Ignoring it is worse than a unlikely patching race.
            * Also machine checks tend to be broadcast and if one CPU
            * goes into machine check the others follow quickly, so we don't
            * expect a machine check to cause undue problems during to code
            * patching.
    
    So undo the machine check related parts of
    8f4e956b NMIs are still disabled.
    
    This only removes code, the only additions are a new comment.
    Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
    Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
    123aa76e
mce_32.c 1.52 KB
/*
 * mce.c - x86 Machine Check Exception Reporting
 * (c) 2002 Alan Cox <alan@lxorguk.ukuu.org.uk>, Dave Jones <davej@redhat.com>
 */

#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/smp.h>
#include <linux/thread_info.h>

#include <asm/processor.h>
#include <asm/system.h>
#include <asm/mce.h>

#include "mce.h"

int mce_disabled;
int nr_mce_banks;

EXPORT_SYMBOL_GPL(nr_mce_banks);	/* non-fatal.o */

/* Handle unconfigured int18 (should never happen) */
static void unexpected_machine_check(struct pt_regs *regs, long error_code)
{
	printk(KERN_ERR "CPU#%d: Unexpected int18 (Machine Check).\n", smp_processor_id());
}

/* Call the installed machine check handler for this CPU setup. */
void (*machine_check_vector)(struct pt_regs *, long error_code) = unexpected_machine_check;

/* This has to be run for each processor */
void mcheck_init(struct cpuinfo_x86 *c)
{
	if (mce_disabled == 1)
		return;

	switch (c->x86_vendor) {
	case X86_VENDOR_AMD:
		amd_mcheck_init(c);
		break;

	case X86_VENDOR_INTEL:
		if (c->x86 == 5)
			intel_p5_mcheck_init(c);
		if (c->x86 == 6)
			intel_p6_mcheck_init(c);
		if (c->x86 == 15)
			intel_p4_mcheck_init(c);
		break;

	case X86_VENDOR_CENTAUR:
		if (c->x86 == 5)
			winchip_mcheck_init(c);
		break;

	default:
		break;
	}
}

static int __init mcheck_disable(char *str)
{
	mce_disabled = 1;
	return 1;
}

static int __init mcheck_enable(char *str)
{
	mce_disabled = -1;
	return 1;
}

__setup("nomce", mcheck_disable);
__setup("mce", mcheck_enable);