[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;
static struct trace_array *hw_branch_trace __read_mostly;


/*
 * 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);
}

/*
 * Stop 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)
{
	hw_branch_trace = tr;

	bts_trace_start(tr);

	return 0;
}

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

static void bts_trace_print_header(struct seq_file *m)
{
	seq_puts(m, "# CPU#        TO  <-  FROM\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;
	unsigned long symflags = TRACE_ITER_SYM_OFFSET;

	trace_assign_type(it, entry);

	if (entry->type == TRACE_HW_BRANCHES) {
		if (trace_seq_printf(seq, "%4d  ", iter->cpu) &&
		    seq_print_ip_sym(seq, it->to, symflags) &&
		    trace_seq_printf(seq, "\t  <-  ") &&
		    seq_print_ip_sym(seq, it->from, symflags) &&
		    trace_seq_printf(seq, "\n"))
			return TRACE_TYPE_HANDLED;
		return TRACE_TYPE_PARTIAL_LINE;;
	}
	return TRACE_TYPE_UNHANDLED;
}

void trace_hw_branch(u64 from, u64 to)
{
	struct trace_array *tr = hw_branch_trace;
	struct ring_buffer_event *event;
	struct hw_branch_entry *entry;
	unsigned long irq1;
	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 = trace_buffer_lock_reserve(tr, TRACE_HW_BRANCHES,
					  sizeof(*entry), 0, 0);
	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->from = from;
	entry->to   = to;
	trace_buffer_unlock_commit(tr, event, 0, 0);

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

static void trace_bts_at(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(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 (unlikely(!tr))
		return;

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

	if (unlikely(!this_tracer))
		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(trace, at);

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

static void trace_bts_close(struct trace_iterator *iter)
{
	tracing_reset_online_cpus(iter->tr);
}

void trace_hw_branch_oops(void)
{
	mutex_lock(&bts_tracer_mutex);

	trace_bts_cpu(hw_branch_trace);

	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,
	.close		= trace_bts_close
};

__init static int init_bts_trace(void)
{
	register_hotcpu_notifier(&bts_hotcpu_notifier);
	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;
b1818748	43	static struct trace_array *hw_branch_trace __read_mostly;
1e9b51c2	44
5c5317de MM	45
	46	/*
	47	* Start tracing on the current cpu.
	48	* The argument is ignored.
	49	*
	50	* pre: bts_tracer_mutex must be locked.
	51	*/
1e9b51c2 MM	52	static void bts_trace_start_cpu(void *arg)
1e9b51c2 MM	53	{
a93751ca MM	54	if (this_tracer)
	55	ds_release_bts(this_tracer);
	56
1e9b51c2 MM	57	this_tracer =
1e9b51c2 MM	58	ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
a93751ca MM	59	/* ovfl = / NULL, / th = */ (size_t)-1,
a93751ca MM	60	BTS_KERNEL);
1e9b51c2 MM	61	if (IS_ERR(this_tracer)) {
	62	this_tracer = NULL;
	63	return;
	64	}
1e9b51c2 MM	65	}
	66
	67	static void bts_trace_start(struct trace_array *tr)
	68	{
5c5317de	69	mutex_lock(&bts_tracer_mutex);
1e9b51c2	70
5c5317de MM	71	on_each_cpu(bts_trace_start_cpu, NULL, 1);
5c5317de MM	72	trace_hw_branches_enabled = 1;
1e9b51c2	73
5c5317de	74	mutex_unlock(&bts_tracer_mutex);
1e9b51c2 MM	75	}
1e9b51c2 MM	76
5c5317de	77	/*
c3706f00	78	* Stop tracing on the current cpu.
5c5317de MM	79	* The argument is ignored.
	80	*
	81	* pre: bts_tracer_mutex must be locked.
	82	*/
1e9b51c2 MM	83	static void bts_trace_stop_cpu(void *arg)
	84	{
	85	if (this_tracer) {
1e9b51c2 MM	86	ds_release_bts(this_tracer);
	87	this_tracer = NULL;
	88	}
	89	}
	90
	91	static void bts_trace_stop(struct trace_array *tr)
	92	{
5c5317de MM	93	mutex_lock(&bts_tracer_mutex);
	94
	95	trace_hw_branches_enabled = 0;
	96	on_each_cpu(bts_trace_stop_cpu, NULL, 1);
1e9b51c2	97
5c5317de MM	98	mutex_unlock(&bts_tracer_mutex);
	99	}
	100
	101	static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
	102	unsigned long action, void *hcpu)
	103	{
	104	unsigned int cpu = (unsigned long)hcpu;
	105
	106	mutex_lock(&bts_tracer_mutex);
	107
	108	if (!trace_hw_branches_enabled)
	109	goto out;
	110
	111	switch (action) {
	112	case CPU_ONLINE:
	113	case CPU_DOWN_FAILED:
	114	smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
	115	break;
	116	case CPU_DOWN_PREPARE:
1e9b51c2	117	smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
5c5317de MM	118	break;
	119	}
	120
	121	out:
	122	mutex_unlock(&bts_tracer_mutex);
	123	return NOTIFY_DONE;
1e9b51c2 MM	124	}
1e9b51c2 MM	125
5c5317de MM	126	static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
	127	.notifier_call = bts_hotcpu_handler
	128	};
	129
5e01cb69	130	static int bts_trace_init(struct trace_array *tr)
1e9b51c2	131	{
b1818748 MM	132	hw_branch_trace = tr;
b1818748 MM	133
1e9b51c2 MM	134	bts_trace_start(tr);
	135
	136	return 0;
	137	}
	138
5e01cb69	139	static void bts_trace_reset(struct trace_array *tr)
5c5317de MM	140	{
5c5317de MM	141	bts_trace_stop(tr);
5c5317de MM	142	}
5c5317de MM	143
1e9b51c2 MM	144	static void bts_trace_print_header(struct seq_file *m)
1e9b51c2 MM	145	{
11edda06	146	seq_puts(m, "# CPU# TO <- FROM\n");
1e9b51c2 MM	147	}
	148
	149	static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
	150	{
	151	struct trace_entry *entry = iter->ent;
	152	struct trace_seq *seq = &iter->seq;
a93751ca	153	struct hw_branch_entry *it;
11edda06	154	unsigned long symflags = TRACE_ITER_SYM_OFFSET;
1e9b51c2 MM	155
	156	trace_assign_type(it, entry);
	157
a93751ca	158	if (entry->type == TRACE_HW_BRANCHES) {
1830b52d	159	if (trace_seq_printf(seq, "%4d ", iter->cpu) &&
11edda06 MM	160	seq_print_ip_sym(seq, it->to, symflags) &&
	161	trace_seq_printf(seq, "\t <- ") &&
	162	seq_print_ip_sym(seq, it->from, symflags) &&
a93751ca MM	163	trace_seq_printf(seq, "\n"))
	164	return TRACE_TYPE_HANDLED;
	165	return TRACE_TYPE_PARTIAL_LINE;;
1e9b51c2 MM	166	}
	167	return TRACE_TYPE_UNHANDLED;
	168	}
	169
b1818748	170	void trace_hw_branch(u64 from, u64 to)
1e9b51c2	171	{
b1818748	172	struct trace_array *tr = hw_branch_trace;
1e9b51c2	173	struct ring_buffer_event *event;
a93751ca	174	struct hw_branch_entry *entry;
0a987751	175	unsigned long irq1;
5c5317de	176	int cpu;
1e9b51c2	177
5c5317de MM	178	if (unlikely(!tr))
	179	return;
	180
	181	if (unlikely(!trace_hw_branches_enabled))
1e9b51c2	182	return;
5c5317de MM	183
	184	local_irq_save(irq1);
	185	cpu = raw_smp_processor_id();
	186	if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
	187	goto out;
	188
51a763dd ACM	189	event = trace_buffer_lock_reserve(tr, TRACE_HW_BRANCHES,
51a763dd ACM	190	sizeof(*entry), 0, 0);
5c5317de MM	191	if (!event)
5c5317de MM	192	goto out;
1e9b51c2 MM	193	entry = ring_buffer_event_data(event);
1e9b51c2 MM	194	tracing_generic_entry_update(&entry->ent, 0, from);
a93751ca	195	entry->ent.type = TRACE_HW_BRANCHES;
1e9b51c2 MM	196	entry->from = from;
1e9b51c2 MM	197	entry->to = to;
51a763dd	198	trace_buffer_unlock_commit(tr, event, 0, 0);
5c5317de MM	199
	200	out:
	201	atomic_dec(&tr->data[cpu]->disabled);
	202	local_irq_restore(irq1);
1e9b51c2 MM	203	}
1e9b51c2 MM	204
b1818748	205	static void trace_bts_at(const struct bts_trace trace, void at)
1e9b51c2	206	{
a93751ca MM	207	struct bts_struct bts;
a93751ca MM	208	int err = 0;
1e9b51c2	209
a93751ca MM	210	WARN_ON_ONCE(!trace->read);
a93751ca MM	211	if (!trace->read)
1e9b51c2 MM	212	return;
1e9b51c2 MM	213
a93751ca MM	214	err = trace->read(this_tracer, at, &bts);
	215	if (err < 0)
	216	return;
1e9b51c2	217
a93751ca MM	218	switch (bts.qualifier) {
a93751ca MM	219	case BTS_BRANCH:
b1818748	220	trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to);
a93751ca MM	221	break;
a93751ca MM	222	}
1e9b51c2 MM	223	}
1e9b51c2 MM	224
5c5317de MM	225	/*
	226	* Collect the trace on the current cpu and write it into the ftrace buffer.
	227	*
	228	* pre: bts_tracer_mutex must be locked
	229	*/
1e9b51c2 MM	230	static void trace_bts_cpu(void *arg)
	231	{
	232	struct trace_array tr = (struct trace_array ) arg;
a93751ca MM	233	const struct bts_trace *trace;
a93751ca MM	234	unsigned char *at;
1e9b51c2	235
b1818748	236	if (unlikely(!tr))
1e9b51c2 MM	237	return;
1e9b51c2 MM	238
5c5317de MM	239	if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
	240	return;
	241
b1818748 MM	242	if (unlikely(!this_tracer))
	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;
a93751ca MM	251	at += trace->ds.size)
b1818748	252	trace_bts_at(trace, at);
1e9b51c2	253
a93751ca MM	254	for (at = trace->ds.begin; (void *)at < trace->ds.top;
a93751ca MM	255	at += trace->ds.size)
b1818748	256	trace_bts_at(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	}
1e9b51c2 MM	270
e23b8ad8 MM	271	static void trace_bts_close(struct trace_iterator *iter)
	272	{
	273	tracing_reset_online_cpus(iter->tr);
	274	}
	275
b1818748 MM	276	void trace_hw_branch_oops(void)
	277	{
	278	mutex_lock(&bts_tracer_mutex);
	279
	280	trace_bts_cpu(hw_branch_trace);
	281
	282	mutex_unlock(&bts_tracer_mutex);
	283	}
	284
1e9b51c2 MM	285	struct tracer bts_tracer __read_mostly =
1e9b51c2 MM	286	{
a93751ca	287	.name = "hw-branch-tracer",
1e9b51c2	288	.init = bts_trace_init,
5c5317de	289	.reset = bts_trace_reset,
1e9b51c2 MM	290	.print_header = bts_trace_print_header,
	291	.print_line = bts_trace_print_line,
	292	.start = bts_trace_start,
	293	.stop = bts_trace_stop,
e23b8ad8 MM	294	.open = trace_bts_prepare,
e23b8ad8 MM	295	.close = trace_bts_close
1e9b51c2 MM	296	};
	297
	298	__init static int init_bts_trace(void)
	299	{
5e01cb69	300	register_hotcpu_notifier(&bts_hotcpu_notifier);
1e9b51c2 MM	301	return register_tracer(&bts_tracer);
	302	}
	303	device_initcall(init_bts_trace);