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Commit fbe9ff9e authored by Borislav Petkov's avatar Borislav Petkov Committed by Ingo Molnar
Browse files

x86/mce: Get rid of register_mce_write_callback() 



Make the mcelog call a notifier which lands in the injector module and
does the injection. This allows for mce-inject to be a normal kernel
module now.

Tested-by: default avatarYazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Acked-by: default avatarYazen Ghannam <yazen.ghannam@amd.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/20170613162835.30750-5-bp@alien8.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent bc8e80d5

arch/x86/include/asm/mce.h

+0 −4
Original line number Diff line number Diff line
@@ -285,10 +285,6 @@ int mce_notify_irq(void); 


DECLARE_PER_CPU(struct mce, injectm);



extern void register_mce_write_callback(ssize_t (*)(struct file *filp,

				    const char __user *ubuf,

				    size_t usize, loff_t *off));



/* Disable CMCI/polling for MCA bank claimed by firmware */

extern void mce_disable_bank(int bank);

arch/x86/kernel/cpu/mcheck/dev-mcelog.c

+37 −10
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 


#include "mce-internal.h"



static BLOCKING_NOTIFIER_HEAD(mce_injector_chain);



static DEFINE_MUTEX(mce_chrdev_read_mutex);



static char mce_helper[128];
@@ -345,24 +347,49 @@ static long mce_chrdev_ioctl(struct file *f, unsigned int cmd, 
	}

}



static ssize_t (*mce_write)(struct file *filp, const char __user *ubuf,

			    size_t usize, loff_t *off);

void mce_register_injector_chain(struct notifier_block *nb)

{

	blocking_notifier_chain_register(&mce_injector_chain, nb);

}

EXPORT_SYMBOL_GPL(mce_register_injector_chain);



void register_mce_write_callback(ssize_t (*fn)(struct file *filp,

			     const char __user *ubuf,

			     size_t usize, loff_t *off))

void mce_unregister_injector_chain(struct notifier_block *nb)

{

	mce_write = fn;

	blocking_notifier_chain_unregister(&mce_injector_chain, nb);

}

EXPORT_SYMBOL_GPL(register_mce_write_callback);

EXPORT_SYMBOL_GPL(mce_unregister_injector_chain);



static ssize_t mce_chrdev_write(struct file *filp, const char __user *ubuf,

				size_t usize, loff_t *off)

{

	if (mce_write)

		return mce_write(filp, ubuf, usize, off);

	else

	struct mce m;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;

	/*

	 * There are some cases where real MSR reads could slip

	 * through.

	 */

	if (!boot_cpu_has(X86_FEATURE_MCE) || !boot_cpu_has(X86_FEATURE_MCA))

		return -EIO;



	if ((unsigned long)usize > sizeof(struct mce))

		usize = sizeof(struct mce);

	if (copy_from_user(&m, ubuf, usize))

		return -EFAULT;



	if (m.extcpu >= num_possible_cpus() || !cpu_online(m.extcpu))

		return -EINVAL;



	/*

	 * Need to give user space some time to set everything up,

	 * so do it a jiffie or two later everywhere.

	 */

	schedule_timeout(2);



	blocking_notifier_call_chain(&mce_injector_chain, 0, &m);



	return usize;

}



static const struct file_operations mce_chrdev_ops = {

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

+19 −47
Original line number Diff line number Diff line
@@ -283,42 +283,24 @@ static void __maybe_unused raise_mce(struct mce *m) 
	}

}



#ifdef CONFIG_X86_MCELOG_LEGACY

/* Error injection interface */

static ssize_t mce_write(struct file *filp, const char __user *ubuf,

			 size_t usize, loff_t *off)

static int mce_inject_raise(struct notifier_block *nb, unsigned long val,

			    void *data)

{

	struct mce m;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;

	/*

	 * There are some cases where real MSR reads could slip

	 * through.

	 */

	if (!boot_cpu_has(X86_FEATURE_MCE) || !boot_cpu_has(X86_FEATURE_MCA))

		return -EIO;



	if ((unsigned long)usize > sizeof(struct mce))

		usize = sizeof(struct mce);

	if (copy_from_user(&m, ubuf, usize))

		return -EFAULT;



	if (m.extcpu >= num_possible_cpus() || !cpu_online(m.extcpu))

		return -EINVAL;

	struct mce *m = (struct mce *)data;



	/*

	 * Need to give user space some time to set everything up,

	 * so do it a jiffie or two later everywhere.

	 */

	schedule_timeout(2);

	if (!m)

		return NOTIFY_DONE;



	mutex_lock(&mce_inject_mutex);

	raise_mce(&m);

	raise_mce(m);

	mutex_unlock(&mce_inject_mutex);

	return usize;



	return NOTIFY_DONE;

}

#endif /* CONFIG_X86_MCELOG_LEGACY */



static struct notifier_block inject_nb = {

	.notifier_call  = mce_inject_raise,

};



/*

 * Caller needs to be make sure this cpu doesn't disappear
@@ -719,44 +701,34 @@ static int __init inject_init(void) 
	if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL))

		return -ENOMEM;



#ifdef CONFIG_X86_MCELOG_LEGACY

		register_mce_write_callback(mce_write);

#endif



	register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0, "mce_notify");



	err = debugfs_init();

	if (err) {

		free_cpumask_var(mce_inject_cpumask);

		return err;

	}



	register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0, "mce_notify");

	mce_register_injector_chain(&inject_nb);



	pr_info("Machine check injector initialized\n");



	return 0;

}



module_init(inject_init);



/*

 * Cannot tolerate unloading currently because we cannot

 * guarantee all openers of mce_chrdev will get a reference to us.

 */

#ifndef CONFIG_X86_MCELOG_LEGACY

static void __exit inject_exit(void)

{



	mce_unregister_injector_chain(&inject_nb);

	unregister_nmi_handler(NMI_LOCAL, "mce_notify");



	debugfs_remove_recursive(dfs_inj);

	dfs_inj = NULL;



	memset(&dfs_fls, 0, sizeof(dfs_fls));



	unregister_nmi_handler(NMI_LOCAL, "mce_notify");



	free_cpumask_var(mce_inject_cpumask);

}



module_init(inject_init);

module_exit(inject_exit);

#endif



MODULE_LICENSE("GPL");

arch/x86/kernel/cpu/mcheck/mce-internal.h

+5 −1
Original line number Diff line number Diff line
@@ -100,7 +100,11 @@ static inline bool mce_cmp(struct mce *m1, struct mce *m2) 
extern struct device_attribute dev_attr_trigger;



#ifdef CONFIG_X86_MCELOG_LEGACY

extern void mce_work_trigger(void);

void mce_work_trigger(void);

void mce_register_injector_chain(struct notifier_block *nb);

void mce_unregister_injector_chain(struct notifier_block *nb);

#else

static inline void mce_work_trigger(void)	{ }

static inline void mce_register_injector_chain(struct notifier_block *nb)	{ }

static inline void mce_unregister_injector_chain(struct notifier_block *nb)	{ }

#endif