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Commit dcfce4a0 authored by Robert Richter's avatar Robert Richter
Browse files

oprofile, x86: Reimplement nmi timer mode using perf event 



The legacy x86 nmi watchdog code was removed with the implementation
of the perf based nmi watchdog. This broke Oprofile's nmi timer
mode. To run nmi timer mode we relied on a continuous ticking nmi
source which the nmi watchdog provided. The nmi tick was no longer
available and current watchdog can not be used anymore since it runs
with very long periods in the range of seconds. This patch
reimplements the nmi timer mode using a perf counter nmi source.

V2:
* removing pr_info()
* fix undefined reference to `__udivdi3' for 32 bit build
* fix section mismatch of .cpuinit.data:nmi_timer_cpu_nb
* removed nmi timer setup in arch/x86
* implemented function stubs for op_nmi_init/exit()
* made code more readable in oprofile_init()

V3:
* fix architectural initialization in oprofile_init()
* fix CONFIG_OPROFILE_NMI_TIMER dependencies

Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarRobert Richter <robert.richter@amd.com>
parent 75c43a20

arch/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -30,6 +30,10 @@ config OPROFILE_EVENT_MULTIPLEX 
config HAVE_OPROFILE

	bool



config OPROFILE_NMI_TIMER

	def_bool y

	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI



config KPROBES

	bool "Kprobes"

	depends on MODULES

arch/x86/oprofile/Makefile

+1 −2
Original line number Diff line number Diff line
@@ -4,9 +4,8 @@ DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \ 
		oprof.o cpu_buffer.o buffer_sync.o \

		event_buffer.o oprofile_files.o \

		oprofilefs.o oprofile_stats.o  \

		timer_int.o )

		timer_int.o nmi_timer_int.o )



oprofile-y				:= $(DRIVER_OBJS) init.o backtrace.o

oprofile-$(CONFIG_X86_LOCAL_APIC) 	+= nmi_int.o op_model_amd.o \

					   op_model_ppro.o op_model_p4.o
 
oprofile-$(CONFIG_X86_IO_APIC)		+= nmi_timer_int.o

arch/x86/oprofile/init.c

+8 −22
Original line number Diff line number Diff line
@@ -16,37 +16,23 @@ 
 * with the NMI mode driver.

 */



#ifdef CONFIG_X86_LOCAL_APIC

extern int op_nmi_init(struct oprofile_operations *ops);

extern int op_nmi_timer_init(struct oprofile_operations *ops);

extern void op_nmi_exit(void);

extern void x86_backtrace(struct pt_regs * const regs, unsigned int depth);

#else

static int op_nmi_init(struct oprofile_operations *ops) { return -ENODEV; }

static void op_nmi_exit(void) { }

#endif



static int nmi_timer;

extern void x86_backtrace(struct pt_regs * const regs, unsigned int depth);



int __init oprofile_arch_init(struct oprofile_operations *ops)

{

	int ret;



	ret = -ENODEV;



#ifdef CONFIG_X86_LOCAL_APIC

	ret = op_nmi_init(ops);

#endif

	nmi_timer = (ret != 0);

#ifdef CONFIG_X86_IO_APIC

	if (nmi_timer)

		ret = op_nmi_timer_init(ops);

#endif

	ops->backtrace = x86_backtrace;



	return ret;

	return op_nmi_init(ops);

}





void oprofile_arch_exit(void)

{

#ifdef CONFIG_X86_LOCAL_APIC

	if (!nmi_timer)

	op_nmi_exit();

#endif

}

arch/x86/oprofile/nmi_timer_int.c

deleted100644 → 0
+0 −66
Original line number Diff line number Diff line 
/**

 * @file nmi_timer_int.c

 *

 * @remark Copyright 2003 OProfile authors

 * @remark Read the file COPYING

 *

 * @author Zwane Mwaikambo <zwane@linuxpower.ca>

 */



#include <linux/init.h>

#include <linux/smp.h>

#include <linux/errno.h>

#include <linux/oprofile.h>

#include <linux/rcupdate.h>

#include <linux/kdebug.h>



#include <asm/nmi.h>

#include <asm/apic.h>

#include <asm/ptrace.h>



static int profile_timer_exceptions_notify(struct notifier_block *self,

					   unsigned long val, void *data)

{

	struct die_args *args = (struct die_args *)data;

	int ret = NOTIFY_DONE;



	switch (val) {

	case DIE_NMI:

		oprofile_add_sample(args->regs, 0);

		ret = NOTIFY_STOP;

		break;

	default:

		break;

	}

	return ret;

}



static struct notifier_block profile_timer_exceptions_nb = {

	.notifier_call = profile_timer_exceptions_notify,

	.next = NULL,

	.priority = NMI_LOW_PRIOR,

};



static int timer_start(void)

{

	if (register_die_notifier(&profile_timer_exceptions_nb))

		return 1;

	return 0;

}





static void timer_stop(void)

{

	unregister_die_notifier(&profile_timer_exceptions_nb);

	synchronize_sched();  /* Allow already-started NMIs to complete. */

}





int __init op_nmi_timer_init(struct oprofile_operations *ops)

{

	ops->start = timer_start;

	ops->stop = timer_stop;

	ops->cpu_type = "timer";

	printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");

	return 0;

}

drivers/oprofile/nmi_timer_int.c

0 → 100644
+173 −0
Original line number Diff line number Diff line 
/**

 * @file nmi_timer_int.c

 *

 * @remark Copyright 2011 Advanced Micro Devices, Inc.

 *

 * @author Robert Richter <robert.richter@amd.com>

 */



#include <linux/init.h>

#include <linux/smp.h>

#include <linux/errno.h>

#include <linux/oprofile.h>

#include <linux/perf_event.h>



#ifdef CONFIG_OPROFILE_NMI_TIMER



static DEFINE_PER_CPU(struct perf_event *, nmi_timer_events);

static int ctr_running;



static struct perf_event_attr nmi_timer_attr = {

	.type           = PERF_TYPE_HARDWARE,

	.config         = PERF_COUNT_HW_CPU_CYCLES,

	.size           = sizeof(struct perf_event_attr),

	.pinned         = 1,

	.disabled       = 1,

};



static void nmi_timer_callback(struct perf_event *event,

			       struct perf_sample_data *data,

			       struct pt_regs *regs)

{

	event->hw.interrupts = 0;       /* don't throttle interrupts */

	oprofile_add_sample(regs, 0);

}



static int nmi_timer_start_cpu(int cpu)

{

	struct perf_event *event = per_cpu(nmi_timer_events, cpu);



	if (!event) {

		event = perf_event_create_kernel_counter(&nmi_timer_attr, cpu, NULL,

							 nmi_timer_callback, NULL);

		if (IS_ERR(event))

			return PTR_ERR(event);

		per_cpu(nmi_timer_events, cpu) = event;

	}



	if (event && ctr_running)

		perf_event_enable(event);



	return 0;

}



static void nmi_timer_stop_cpu(int cpu)

{

	struct perf_event *event = per_cpu(nmi_timer_events, cpu);



	if (event && ctr_running)

		perf_event_disable(event);

}



static int nmi_timer_cpu_notifier(struct notifier_block *b, unsigned long action,

				  void *data)

{

	int cpu = (unsigned long)data;

	switch (action) {

	case CPU_DOWN_FAILED:

	case CPU_ONLINE:

		nmi_timer_start_cpu(cpu);

		break;

	case CPU_DOWN_PREPARE:

		nmi_timer_stop_cpu(cpu);

		break;

	}

	return NOTIFY_DONE;

}



static struct notifier_block nmi_timer_cpu_nb = {

	.notifier_call = nmi_timer_cpu_notifier

};



static int nmi_timer_start(void)

{

	int cpu;



	get_online_cpus();

	ctr_running = 1;

	for_each_online_cpu(cpu)

		nmi_timer_start_cpu(cpu);

	put_online_cpus();



	return 0;

}



static void nmi_timer_stop(void)

{

	int cpu;



	get_online_cpus();

	for_each_online_cpu(cpu)

		nmi_timer_stop_cpu(cpu);

	ctr_running = 0;

	put_online_cpus();

}



static void nmi_timer_shutdown(void)

{

	struct perf_event *event;

	int cpu;



	get_online_cpus();

	unregister_cpu_notifier(&nmi_timer_cpu_nb);

	for_each_possible_cpu(cpu) {

		event = per_cpu(nmi_timer_events, cpu);

		if (!event)

			continue;

		perf_event_disable(event);

		per_cpu(nmi_timer_events, cpu) = NULL;

		perf_event_release_kernel(event);

	}



	put_online_cpus();

}



static int nmi_timer_setup(void)

{

	int cpu, err;

	u64 period;



	/* clock cycles per tick: */

	period = (u64)cpu_khz * 1000;

	do_div(period, HZ);

	nmi_timer_attr.sample_period = period;



	get_online_cpus();

	err = register_cpu_notifier(&nmi_timer_cpu_nb);

	if (err)

		goto out;

	/* can't attach events to offline cpus: */

	for_each_online_cpu(cpu) {

		err = nmi_timer_start_cpu(cpu);

		if (err)

			break;

	}

	if (err)

		nmi_timer_shutdown();

out:

	put_online_cpus();

	return err;

}



int __init op_nmi_timer_init(struct oprofile_operations *ops)

{

	int err = 0;



	err = nmi_timer_setup();

	if (err)

		return err;

	nmi_timer_shutdown();		/* only check, don't alloc */



	ops->create_files	= NULL;

	ops->setup		= nmi_timer_setup;

	ops->shutdown		= nmi_timer_shutdown;

	ops->start		= nmi_timer_start;

	ops->stop		= nmi_timer_stop;

	ops->cpu_type		= "timer";



	printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");



	return 0;

}



#endif