Commit 3adbbcce authored by Don Zickus's avatar Don Zickus Committed by Andi Kleen
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[PATCH] x86: Cleanup NMI interrupt path 



This patch cleans up the NMI interrupt path.  Instead of being gated by if
the 'nmi callback' is set, the interrupt handler now calls everyone who is
registered on the die_chain and additionally checks the nmi watchdog,
reseting it if enabled.  This allows more subsystems to hook into the NMI if
they need to (without being block by set_nmi_callback).

Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent b7471c6d

arch/i386/kernel/nmi.c

+13 −3
Original line number Diff line number Diff line
@@ -781,7 +781,7 @@ EXPORT_SYMBOL(touch_nmi_watchdog); 


extern void die_nmi(struct pt_regs *, const char *msg);



void nmi_watchdog_tick (struct pt_regs * regs, unsigned reason)

int nmi_watchdog_tick (struct pt_regs * regs, unsigned reason)

{



	/*
@@ -794,10 +794,12 @@ void nmi_watchdog_tick (struct pt_regs * regs, unsigned reason) 
	int cpu = smp_processor_id();

	struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

	u64 dummy;

	int rc=0;



	/* check for other users first */

	if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)

			== NOTIFY_STOP) {

		rc = 1;

		touched = 1;

	}
@@ -850,10 +852,18 @@ void nmi_watchdog_tick (struct pt_regs * regs, unsigned reason) 
			}

			/* start the cycle over again */

			write_watchdog_counter(wd->perfctr_msr, NULL);

		}

			rc = 1;

		} else if (nmi_watchdog == NMI_IO_APIC) {

			/* don't know how to accurately check for this.

			 * just assume it was a watchdog timer interrupt

			 * This matches the old behaviour.

			 */

			rc = 1;

		} else

			printk(KERN_WARNING "Unknown enabled NMI hardware?!\n");

	}

done:

	return;

	return rc;

}



#ifdef CONFIG_SYSCTL

arch/i386/kernel/traps.c

+11 −13
Original line number Diff line number Diff line
@@ -706,6 +706,13 @@ void die_nmi (struct pt_regs *regs, const char *msg) 
	do_exit(SIGSEGV);

}



static int dummy_nmi_callback(struct pt_regs * regs, int cpu)

{

	return 0;

}



static nmi_callback_t nmi_callback = dummy_nmi_callback;



static void default_do_nmi(struct pt_regs * regs)

{

	unsigned char reason = 0;
@@ -723,11 +730,10 @@ static void default_do_nmi(struct pt_regs * regs) 
		 * Ok, so this is none of the documented NMI sources,

		 * so it must be the NMI watchdog.

		 */

		if (nmi_watchdog) {

			nmi_watchdog_tick(regs, reason);

		if (nmi_watchdog_tick(regs, reason))

			return;

		}

#endif

		if (!rcu_dereference(nmi_callback)(regs, smp_processor_id()))

			unknown_nmi_error(reason, regs);

		return;

	}
@@ -744,13 +750,6 @@ static void default_do_nmi(struct pt_regs * regs) 
	reassert_nmi();

}



static int dummy_nmi_callback(struct pt_regs * regs, int cpu)

{

	return 0;

}

 

static nmi_callback_t nmi_callback = dummy_nmi_callback;

 

fastcall void do_nmi(struct pt_regs * regs, long error_code)

{

	int cpu;
@@ -761,7 +760,6 @@ fastcall void do_nmi(struct pt_regs * regs, long error_code) 


	++nmi_count(cpu);



	if (!rcu_dereference(nmi_callback)(regs, cpu))

	default_do_nmi(regs);



	nmi_exit();

arch/x86_64/kernel/nmi.c

+19 −7
Original line number Diff line number Diff line
@@ -682,16 +682,18 @@ void touch_nmi_watchdog (void) 
 	touch_softlockup_watchdog();

}



void __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)

int __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)

{

	int sum;

	int touched = 0;

	struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

	u64 dummy;

	int rc=0;



	/* check for other users first */

	if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)

			== NOTIFY_STOP) {

		rc = 1;

		touched = 1;

	}
@@ -746,10 +748,18 @@ void __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason) 
	 		}

			/* start the cycle over again */

			wrmsrl(wd->perfctr_msr, -((u64)cpu_khz * 1000 / nmi_hz));

		}

			rc = 1;

		} else 	if (nmi_watchdog == NMI_IO_APIC) {

			/* don't know how to accurately check for this.

			 * just assume it was a watchdog timer interrupt

			 * This matches the old behaviour.

			 */

			rc = 1;

		} else

			printk(KERN_WARNING "Unknown enabled NMI hardware?!\n");

	}

done:

	return;

	return rc;

}



static __kprobes int dummy_nmi_callback(struct pt_regs * regs, int cpu)
@@ -761,15 +771,17 @@ static nmi_callback_t nmi_callback = dummy_nmi_callback; 
 

asmlinkage __kprobes void do_nmi(struct pt_regs * regs, long error_code)

{

	int cpu = safe_smp_processor_id();



	nmi_enter();

	add_pda(__nmi_count,1);

	if (!rcu_dereference(nmi_callback)(regs, cpu))

	default_do_nmi(regs);

	nmi_exit();

}



int do_nmi_callback(struct pt_regs * regs, int cpu)

{

	return rcu_dereference(nmi_callback)(regs, cpu);

}



void set_nmi_callback(nmi_callback_t callback)

{

	vmalloc_sync_all();

arch/x86_64/kernel/traps.c

+4 −4
Original line number Diff line number Diff line
@@ -781,12 +781,12 @@ asmlinkage __kprobes void default_do_nmi(struct pt_regs *regs) 
		 * Ok, so this is none of the documented NMI sources,

		 * so it must be the NMI watchdog.

		 */

		if (nmi_watchdog > 0) {

			nmi_watchdog_tick(regs,reason);

		if (nmi_watchdog_tick(regs,reason))

			return;

		}

		if (!do_nmi_callback(regs,cpu))

#endif

			unknown_nmi_error(reason, regs);



		return;

	}

	if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)

include/asm-i386/nmi.h

+1 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ extern int reserve_lapic_nmi(void); 
extern void release_lapic_nmi(void);

extern void disable_timer_nmi_watchdog(void);

extern void enable_timer_nmi_watchdog(void);

extern void nmi_watchdog_tick (struct pt_regs * regs, unsigned reason);

extern int nmi_watchdog_tick (struct pt_regs * regs, unsigned reason);



extern atomic_t nmi_active;

extern unsigned int nmi_watchdog;

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