[deliverable/linux.git] / kernel / trace / trace_hw_branches.c

/*
 * h/w branch tracer for x86 based on bts
 *
 * Copyright (C) 2008-2009 Intel Corporation.
 * Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009
 *
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/ftrace.h>
#include <linux/kallsyms.h>
#include <linux/mutex.h>
#include <linux/cpu.h>
#include <linux/smp.h>

#include <asm/ds.h>

#include "trace.h"
#include "trace_output.h"


#define SIZEOF_BTS (1 << 13)

/* The tracer mutex protects the below per-cpu tracer array.
   It needs to be held to:
   - start tracing on all cpus
   - stop tracing on all cpus
   - start tracing on a single hotplug cpu
   - stop tracing on a single hotplug cpu
   - read the trace from all cpus
   - read the trace from a single cpu
*/
static DEFINE_MUTEX(bts_tracer_mutex);
static DEFINE_PER_CPU(struct bts_tracer *, tracer);
static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);

#define this_tracer per_cpu(tracer, smp_processor_id())
#define this_buffer per_cpu(buffer, smp_processor_id())

static int __read_mostly trace_hw_branches_enabled;


/*
 * Start tracing on the current cpu.
 * The argument is ignored.
 *
 * pre: bts_tracer_mutex must be locked.
 */
static void bts_trace_start_cpu(void *arg)
{
	if (this_tracer)
		ds_release_bts(this_tracer);

	this_tracer =
		ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
			       /* ovfl = */ NULL, /* th = */ (size_t)-1,
			       BTS_KERNEL);
	if (IS_ERR(this_tracer)) {
		this_tracer = NULL;
		return;
	}
}

static void bts_trace_start(struct trace_array *tr)
{
	mutex_lock(&bts_tracer_mutex);

	on_each_cpu(bts_trace_start_cpu, NULL, 1);
	trace_hw_branches_enabled = 1;

	mutex_unlock(&bts_tracer_mutex);
}

/*
 * Start tracing on the current cpu.
 * The argument is ignored.
 *
 * pre: bts_tracer_mutex must be locked.
 */
static void bts_trace_stop_cpu(void *arg)
{
	if (this_tracer) {
		ds_release_bts(this_tracer);
		this_tracer = NULL;
	}
}

static void bts_trace_stop(struct trace_array *tr)
{
	mutex_lock(&bts_tracer_mutex);

	trace_hw_branches_enabled = 0;
	on_each_cpu(bts_trace_stop_cpu, NULL, 1);

	mutex_unlock(&bts_tracer_mutex);
}

static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
				     unsigned long action, void *hcpu)
{
	unsigned int cpu = (unsigned long)hcpu;

	mutex_lock(&bts_tracer_mutex);

	if (!trace_hw_branches_enabled)
		goto out;

	switch (action) {
	case CPU_ONLINE:
	case CPU_DOWN_FAILED:
		smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
		break;
	case CPU_DOWN_PREPARE:
		smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
		break;
	}

 out:
	mutex_unlock(&bts_tracer_mutex);
	return NOTIFY_DONE;
}

static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
	.notifier_call = bts_hotcpu_handler
};

static int bts_trace_init(struct trace_array *tr)
{
	register_hotcpu_notifier(&bts_hotcpu_notifier);
	tracing_reset_online_cpus(tr);
	bts_trace_start(tr);

	return 0;
}

static void bts_trace_reset(struct trace_array *tr)
{
	bts_trace_stop(tr);
	unregister_hotcpu_notifier(&bts_hotcpu_notifier);
}

static void bts_trace_print_header(struct seq_file *m)
{
	seq_puts(m,
		 "# CPU#        FROM                   TO         FUNCTION\n");
	seq_puts(m,
		 "#  |           |                     |             |\n");
}

static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
{
	struct trace_entry *entry = iter->ent;
	struct trace_seq *seq = &iter->seq;
	struct hw_branch_entry *it;

	trace_assign_type(it, entry);

	if (entry->type == TRACE_HW_BRANCHES) {
		if (trace_seq_printf(seq, "%4d  ", entry->cpu) &&
		    trace_seq_printf(seq, "0x%016llx -> 0x%016llx ",
				     it->from, it->to) &&
		    (!it->from ||
		     seq_print_ip_sym(seq, it->from, /* sym_flags = */ 0)) &&
		    trace_seq_printf(seq, "\n"))
			return TRACE_TYPE_HANDLED;
		return TRACE_TYPE_PARTIAL_LINE;;
	}
	return TRACE_TYPE_UNHANDLED;
}

void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
{
	struct ring_buffer_event *event;
	struct hw_branch_entry *entry;
	unsigned long irq1, irq2;
	int cpu;

	if (unlikely(!tr))
		return;

	if (unlikely(!trace_hw_branches_enabled))
		return;

	local_irq_save(irq1);
	cpu = raw_smp_processor_id();
	if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
		goto out;

	event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq2);
	if (!event)
		goto out;
	entry	= ring_buffer_event_data(event);
	tracing_generic_entry_update(&entry->ent, 0, from);
	entry->ent.type = TRACE_HW_BRANCHES;
	entry->ent.cpu = cpu;
	entry->from = from;
	entry->to   = to;
	ring_buffer_unlock_commit(tr->buffer, event, irq2);

 out:
	atomic_dec(&tr->data[cpu]->disabled);
	local_irq_restore(irq1);
}

static void trace_bts_at(struct trace_array *tr,
			 const struct bts_trace *trace, void *at)
{
	struct bts_struct bts;
	int err = 0;

	WARN_ON_ONCE(!trace->read);
	if (!trace->read)
		return;

	err = trace->read(this_tracer, at, &bts);
	if (err < 0)
		return;

	switch (bts.qualifier) {
	case BTS_BRANCH:
		trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
		break;
	}
}

/*
 * Collect the trace on the current cpu and write it into the ftrace buffer.
 *
 * pre: bts_tracer_mutex must be locked
 */
static void trace_bts_cpu(void *arg)
{
	struct trace_array *tr = (struct trace_array *) arg;
	const struct bts_trace *trace;
	unsigned char *at;

	if (!this_tracer)
		return;

	if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
		return;

	ds_suspend_bts(this_tracer);
	trace = ds_read_bts(this_tracer);
	if (!trace)
		goto out;

	for (at = trace->ds.top; (void *)at < trace->ds.end;
	     at += trace->ds.size)
		trace_bts_at(tr, trace, at);

	for (at = trace->ds.begin; (void *)at < trace->ds.top;
	     at += trace->ds.size)
		trace_bts_at(tr, trace, at);

out:
	ds_resume_bts(this_tracer);
}

static void trace_bts_prepare(struct trace_iterator *iter)
{
	mutex_lock(&bts_tracer_mutex);

	on_each_cpu(trace_bts_cpu, iter->tr, 1);

	mutex_unlock(&bts_tracer_mutex);
}

struct tracer bts_tracer __read_mostly =
{
	.name		= "hw-branch-tracer",
	.init		= bts_trace_init,
	.reset		= bts_trace_reset,
	.print_header	= bts_trace_print_header,
	.print_line	= bts_trace_print_line,
	.start		= bts_trace_start,
	.stop		= bts_trace_stop,
	.open		= trace_bts_prepare
};

__init static int init_bts_trace(void)
{
	return register_tracer(&bts_tracer);
}
device_initcall(init_bts_trace);
Commit	Line	Data
1e9b51c2	1	/*
a93751ca	2	* h/w branch tracer for x86 based on bts
1e9b51c2	3	*
5c5317de MM	4	* Copyright (C) 2008-2009 Intel Corporation.
5c5317de MM	5	* Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009
1e9b51c2 MM	6	*
	7	*/
	8
	9	#include <linux/module.h>
	10	#include <linux/fs.h>
	11	#include <linux/debugfs.h>
	12	#include <linux/ftrace.h>
	13	#include <linux/kallsyms.h>
5c5317de MM	14	#include <linux/mutex.h>
	15	#include <linux/cpu.h>
	16	#include <linux/smp.h>
1e9b51c2 MM	17
	18	#include <asm/ds.h>
	19
	20	#include "trace.h"
f0868d1e	21	#include "trace_output.h"
1e9b51c2 MM	22
	23
	24	#define SIZEOF_BTS (1 << 13)
	25
5c5317de MM	26	/* The tracer mutex protects the below per-cpu tracer array.
	27	It needs to be held to:
	28	- start tracing on all cpus
	29	- stop tracing on all cpus
	30	- start tracing on a single hotplug cpu
	31	- stop tracing on a single hotplug cpu
	32	- read the trace from all cpus
	33	- read the trace from a single cpu
	34	*/
	35	static DEFINE_MUTEX(bts_tracer_mutex);
1e9b51c2 MM	36	static DEFINE_PER_CPU(struct bts_tracer *, tracer);
	37	static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
	38
	39	#define this_tracer per_cpu(tracer, smp_processor_id())
	40	#define this_buffer per_cpu(buffer, smp_processor_id())
	41
5c5317de	42	static int __read_mostly trace_hw_branches_enabled;
1e9b51c2	43
5c5317de MM	44
	45	/*
	46	* Start tracing on the current cpu.
	47	* The argument is ignored.
	48	*
	49	* pre: bts_tracer_mutex must be locked.
	50	*/
1e9b51c2 MM	51	static void bts_trace_start_cpu(void *arg)
1e9b51c2 MM	52	{
a93751ca MM	53	if (this_tracer)
	54	ds_release_bts(this_tracer);
	55
1e9b51c2 MM	56	this_tracer =
1e9b51c2 MM	57	ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
a93751ca MM	58	/* ovfl = / NULL, / th = */ (size_t)-1,
a93751ca MM	59	BTS_KERNEL);
1e9b51c2 MM	60	if (IS_ERR(this_tracer)) {
	61	this_tracer = NULL;
	62	return;
	63	}
1e9b51c2 MM	64	}
	65
	66	static void bts_trace_start(struct trace_array *tr)
	67	{
5c5317de	68	mutex_lock(&bts_tracer_mutex);
1e9b51c2	69
5c5317de MM	70	on_each_cpu(bts_trace_start_cpu, NULL, 1);
5c5317de MM	71	trace_hw_branches_enabled = 1;
1e9b51c2	72
5c5317de	73	mutex_unlock(&bts_tracer_mutex);
1e9b51c2 MM	74	}
1e9b51c2 MM	75
5c5317de MM	76	/*
	77	* Start tracing on the current cpu.
	78	* The argument is ignored.
	79	*
	80	* pre: bts_tracer_mutex must be locked.
	81	*/
1e9b51c2 MM	82	static void bts_trace_stop_cpu(void *arg)
	83	{
	84	if (this_tracer) {
1e9b51c2 MM	85	ds_release_bts(this_tracer);
	86	this_tracer = NULL;
	87	}
	88	}
	89
	90	static void bts_trace_stop(struct trace_array *tr)
	91	{
5c5317de MM	92	mutex_lock(&bts_tracer_mutex);
	93
	94	trace_hw_branches_enabled = 0;
	95	on_each_cpu(bts_trace_stop_cpu, NULL, 1);
1e9b51c2	96
5c5317de MM	97	mutex_unlock(&bts_tracer_mutex);
	98	}
	99
	100	static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
	101	unsigned long action, void *hcpu)
	102	{
	103	unsigned int cpu = (unsigned long)hcpu;
	104
	105	mutex_lock(&bts_tracer_mutex);
	106
	107	if (!trace_hw_branches_enabled)
	108	goto out;
	109
	110	switch (action) {
	111	case CPU_ONLINE:
	112	case CPU_DOWN_FAILED:
	113	smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
	114	break;
	115	case CPU_DOWN_PREPARE:
1e9b51c2	116	smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
5c5317de MM	117	break;
	118	}
	119
	120	out:
	121	mutex_unlock(&bts_tracer_mutex);
	122	return NOTIFY_DONE;
1e9b51c2 MM	123	}
1e9b51c2 MM	124
5c5317de MM	125	static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
	126	.notifier_call = bts_hotcpu_handler
	127	};
	128
1e9b51c2 MM	129	static int bts_trace_init(struct trace_array *tr)
1e9b51c2 MM	130	{
5c5317de	131	register_hotcpu_notifier(&bts_hotcpu_notifier);
213cc060	132	tracing_reset_online_cpus(tr);
1e9b51c2 MM	133	bts_trace_start(tr);
	134
	135	return 0;
	136	}
	137
5c5317de MM	138	static void bts_trace_reset(struct trace_array *tr)
	139	{
	140	bts_trace_stop(tr);
	141	unregister_hotcpu_notifier(&bts_hotcpu_notifier);
	142	}
	143
1e9b51c2 MM	144	static void bts_trace_print_header(struct seq_file *m)
1e9b51c2 MM	145	{
1e9b51c2 MM	146	seq_puts(m,
	147	"# CPU# FROM TO FUNCTION\n");
	148	seq_puts(m,
	149	"# \| \| \| \|\n");
1e9b51c2 MM	150	}
	151
	152	static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
	153	{
	154	struct trace_entry *entry = iter->ent;
	155	struct trace_seq *seq = &iter->seq;
a93751ca	156	struct hw_branch_entry *it;
1e9b51c2 MM	157
	158	trace_assign_type(it, entry);
	159
a93751ca MM	160	if (entry->type == TRACE_HW_BRANCHES) {
	161	if (trace_seq_printf(seq, "%4d ", entry->cpu) &&
	162	trace_seq_printf(seq, "0x%016llx -> 0x%016llx ",
	163	it->from, it->to) &&
	164	(!it->from \|\|
	165	seq_print_ip_sym(seq, it->from, /* sym_flags = */ 0)) &&
	166	trace_seq_printf(seq, "\n"))
	167	return TRACE_TYPE_HANDLED;
	168	return TRACE_TYPE_PARTIAL_LINE;;
1e9b51c2 MM	169	}
	170	return TRACE_TYPE_UNHANDLED;
	171	}
	172
a93751ca	173	void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
1e9b51c2 MM	174	{
1e9b51c2 MM	175	struct ring_buffer_event *event;
a93751ca	176	struct hw_branch_entry *entry;
5c5317de MM	177	unsigned long irq1, irq2;
5c5317de MM	178	int cpu;
1e9b51c2	179
5c5317de MM	180	if (unlikely(!tr))
	181	return;
	182
	183	if (unlikely(!trace_hw_branches_enabled))
1e9b51c2	184	return;
5c5317de MM	185
	186	local_irq_save(irq1);
	187	cpu = raw_smp_processor_id();
	188	if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
	189	goto out;
	190
	191	event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq2);
	192	if (!event)
	193	goto out;
1e9b51c2 MM	194	entry = ring_buffer_event_data(event);
1e9b51c2 MM	195	tracing_generic_entry_update(&entry->ent, 0, from);
a93751ca	196	entry->ent.type = TRACE_HW_BRANCHES;
5c5317de	197	entry->ent.cpu = cpu;
1e9b51c2 MM	198	entry->from = from;
1e9b51c2 MM	199	entry->to = to;
5c5317de MM	200	ring_buffer_unlock_commit(tr->buffer, event, irq2);
	201
	202	out:
	203	atomic_dec(&tr->data[cpu]->disabled);
	204	local_irq_restore(irq1);
1e9b51c2 MM	205	}
1e9b51c2 MM	206
a93751ca MM	207	static void trace_bts_at(struct trace_array *tr,
a93751ca MM	208	const struct bts_trace trace, void at)
1e9b51c2	209	{
a93751ca MM	210	struct bts_struct bts;
a93751ca MM	211	int err = 0;
1e9b51c2	212
a93751ca MM	213	WARN_ON_ONCE(!trace->read);
a93751ca MM	214	if (!trace->read)
1e9b51c2 MM	215	return;
1e9b51c2 MM	216
a93751ca MM	217	err = trace->read(this_tracer, at, &bts);
	218	if (err < 0)
	219	return;
1e9b51c2	220
a93751ca MM	221	switch (bts.qualifier) {
	222	case BTS_BRANCH:
	223	trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
	224	break;
	225	}
1e9b51c2 MM	226	}
1e9b51c2 MM	227
5c5317de MM	228	/*
	229	* Collect the trace on the current cpu and write it into the ftrace buffer.
	230	*
	231	* pre: bts_tracer_mutex must be locked
	232	*/
1e9b51c2 MM	233	static void trace_bts_cpu(void *arg)
	234	{
	235	struct trace_array tr = (struct trace_array ) arg;
a93751ca MM	236	const struct bts_trace *trace;
a93751ca MM	237	unsigned char *at;
1e9b51c2 MM	238
	239	if (!this_tracer)
	240	return;
	241
5c5317de MM	242	if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
	243	return;
	244
a93751ca MM	245	ds_suspend_bts(this_tracer);
	246	trace = ds_read_bts(this_tracer);
	247	if (!trace)
1e9b51c2 MM	248	goto out;
1e9b51c2 MM	249
a93751ca MM	250	for (at = trace->ds.top; (void *)at < trace->ds.end;
	251	at += trace->ds.size)
	252	trace_bts_at(tr, trace, at);
1e9b51c2	253
a93751ca MM	254	for (at = trace->ds.begin; (void *)at < trace->ds.top;
	255	at += trace->ds.size)
	256	trace_bts_at(tr, trace, at);
1e9b51c2 MM	257
1e9b51c2 MM	258	out:
a93751ca	259	ds_resume_bts(this_tracer);
1e9b51c2 MM	260	}
	261
	262	static void trace_bts_prepare(struct trace_iterator *iter)
	263	{
5c5317de MM	264	mutex_lock(&bts_tracer_mutex);
	265
	266	on_each_cpu(trace_bts_cpu, iter->tr, 1);
1e9b51c2	267
5c5317de	268	mutex_unlock(&bts_tracer_mutex);
1e9b51c2 MM	269	}
	270
	271	struct tracer bts_tracer __read_mostly =
	272	{
a93751ca	273	.name = "hw-branch-tracer",
1e9b51c2	274	.init = bts_trace_init,
5c5317de	275	.reset = bts_trace_reset,
1e9b51c2 MM	276	.print_header = bts_trace_print_header,
	277	.print_line = bts_trace_print_line,
	278	.start = bts_trace_start,
	279	.stop = bts_trace_stop,
	280	.open = trace_bts_prepare
	281	};
	282
	283	__init static int init_bts_trace(void)
	284	{
	285	return register_tracer(&bts_tracer);
	286	}
	287	device_initcall(init_bts_trace);