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

#include <asm/ds.h>

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


#define SIZEOF_BTS (1 << 13)

/*
 * The tracer lock 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_SPINLOCK(bts_tracer_lock);
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_lock 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)
{
	spin_lock(&bts_tracer_lock);

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

	spin_unlock(&bts_tracer_lock);
}

/*
 * Stop tracing on the current cpu.
 * The argument is ignored.
 *
 * pre: bts_tracer_lock 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)
{
	spin_lock(&bts_tracer_lock);

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

	spin_unlock(&bts_tracer_lock);
}

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

	spin_lock(&bts_tracer_lock);

	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:
	spin_unlock(&bts_tracer_lock);
	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_lock 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)
{
	spin_lock(&bts_tracer_lock);

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

	spin_unlock(&bts_tracer_lock);
}

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

void trace_hw_branch_oops(void)
{
	spin_lock(&bts_tracer_lock);

	trace_bts_cpu(hw_branch_trace);

	spin_unlock(&bts_tracer_lock);
}

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	6	*/
2d542cf3 IM	7	#include <linux/spinlock.h>
2d542cf3 IM	8	#include <linux/kallsyms.h>
1e9b51c2 MM	9	#include <linux/debugfs.h>
1e9b51c2 MM	10	#include <linux/ftrace.h>
2d542cf3	11	#include <linux/module.h>
5c5317de MM	12	#include <linux/cpu.h>
5c5317de MM	13	#include <linux/smp.h>
2d542cf3	14	#include <linux/fs.h>
1e9b51c2 MM	15
	16	#include <asm/ds.h>
	17
	18	#include "trace.h"
f0868d1e	19	#include "trace_output.h"
1e9b51c2 MM	20
	21
	22	#define SIZEOF_BTS (1 << 13)
	23
2d542cf3 IM	24	/*
	25	* The tracer lock protects the below per-cpu tracer array.
	26	* It needs to be held to:
	27	* - start tracing on all cpus
	28	* - stop tracing on all cpus
	29	* - start tracing on a single hotplug cpu
	30	* - stop tracing on a single hotplug cpu
	31	* - read the trace from all cpus
	32	* - read the trace from a single cpu
	33	*/
	34	static DEFINE_SPINLOCK(bts_tracer_lock);
1e9b51c2 MM	35	static DEFINE_PER_CPU(struct bts_tracer *, tracer);
	36	static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
	37
	38	#define this_tracer per_cpu(tracer, smp_processor_id())
	39	#define this_buffer per_cpu(buffer, smp_processor_id())
	40
5c5317de	41	static int __read_mostly trace_hw_branches_enabled;
b1818748	42	static struct trace_array *hw_branch_trace __read_mostly;
1e9b51c2	43
5c5317de MM	44
	45	/*
	46	* Start tracing on the current cpu.
	47	* The argument is ignored.
	48	*
2d542cf3	49	* pre: bts_tracer_lock must be locked.
5c5317de	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	{
2d542cf3	68	spin_lock(&bts_tracer_lock);
1e9b51c2	69
5c5317de MM	70	on_each_cpu(bts_trace_start_cpu, NULL, 1);
5c5317de MM	71	trace_hw_branches_enabled = 1;
1e9b51c2	72
2d542cf3	73	spin_unlock(&bts_tracer_lock);
1e9b51c2 MM	74	}
1e9b51c2 MM	75
5c5317de	76	/*
c3706f00	77	* Stop tracing on the current cpu.
5c5317de MM	78	* The argument is ignored.
5c5317de MM	79	*
2d542cf3	80	* pre: bts_tracer_lock must be locked.
5c5317de	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	{
2d542cf3	92	spin_lock(&bts_tracer_lock);
5c5317de MM	93
	94	trace_hw_branches_enabled = 0;
	95	on_each_cpu(bts_trace_stop_cpu, NULL, 1);
1e9b51c2	96
2d542cf3	97	spin_unlock(&bts_tracer_lock);
5c5317de MM	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
2d542cf3	105	spin_lock(&bts_tracer_lock);
5c5317de MM	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:
2d542cf3	121	spin_unlock(&bts_tracer_lock);
5c5317de	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
5e01cb69	129	static int bts_trace_init(struct trace_array *tr)
1e9b51c2	130	{
b1818748 MM	131	hw_branch_trace = tr;
b1818748 MM	132
1e9b51c2 MM	133	bts_trace_start(tr);
	134
	135	return 0;
	136	}
	137
5e01cb69	138	static void bts_trace_reset(struct trace_array *tr)
5c5317de MM	139	{
5c5317de MM	140	bts_trace_stop(tr);
5c5317de MM	141	}
5c5317de MM	142
1e9b51c2 MM	143	static void bts_trace_print_header(struct seq_file *m)
1e9b51c2 MM	144	{
11edda06	145	seq_puts(m, "# CPU# TO <- FROM\n");
1e9b51c2 MM	146	}
	147
	148	static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
	149	{
	150	struct trace_entry *entry = iter->ent;
	151	struct trace_seq *seq = &iter->seq;
a93751ca	152	struct hw_branch_entry *it;
11edda06	153	unsigned long symflags = TRACE_ITER_SYM_OFFSET;
1e9b51c2 MM	154
	155	trace_assign_type(it, entry);
	156
a93751ca	157	if (entry->type == TRACE_HW_BRANCHES) {
1830b52d	158	if (trace_seq_printf(seq, "%4d ", iter->cpu) &&
11edda06 MM	159	seq_print_ip_sym(seq, it->to, symflags) &&
	160	trace_seq_printf(seq, "\t <- ") &&
	161	seq_print_ip_sym(seq, it->from, symflags) &&
a93751ca MM	162	trace_seq_printf(seq, "\n"))
	163	return TRACE_TYPE_HANDLED;
	164	return TRACE_TYPE_PARTIAL_LINE;;
1e9b51c2 MM	165	}
	166	return TRACE_TYPE_UNHANDLED;
	167	}
	168
b1818748	169	void trace_hw_branch(u64 from, u64 to)
1e9b51c2	170	{
b1818748	171	struct trace_array *tr = hw_branch_trace;
1e9b51c2	172	struct ring_buffer_event *event;
a93751ca	173	struct hw_branch_entry *entry;
0a987751	174	unsigned long irq1;
5c5317de	175	int cpu;
1e9b51c2	176
5c5317de MM	177	if (unlikely(!tr))
	178	return;
	179
	180	if (unlikely(!trace_hw_branches_enabled))
1e9b51c2	181	return;
5c5317de MM	182
	183	local_irq_save(irq1);
	184	cpu = raw_smp_processor_id();
	185	if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
	186	goto out;
	187
51a763dd ACM	188	event = trace_buffer_lock_reserve(tr, TRACE_HW_BRANCHES,
51a763dd ACM	189	sizeof(*entry), 0, 0);
5c5317de MM	190	if (!event)
5c5317de MM	191	goto out;
1e9b51c2 MM	192	entry = ring_buffer_event_data(event);
1e9b51c2 MM	193	tracing_generic_entry_update(&entry->ent, 0, from);
a93751ca	194	entry->ent.type = TRACE_HW_BRANCHES;
1e9b51c2 MM	195	entry->from = from;
1e9b51c2 MM	196	entry->to = to;
51a763dd	197	trace_buffer_unlock_commit(tr, event, 0, 0);
5c5317de MM	198
	199	out:
	200	atomic_dec(&tr->data[cpu]->disabled);
	201	local_irq_restore(irq1);
1e9b51c2 MM	202	}
1e9b51c2 MM	203
b1818748	204	static void trace_bts_at(const struct bts_trace trace, void at)
1e9b51c2	205	{
a93751ca MM	206	struct bts_struct bts;
a93751ca MM	207	int err = 0;
1e9b51c2	208
a93751ca MM	209	WARN_ON_ONCE(!trace->read);
a93751ca MM	210	if (!trace->read)
1e9b51c2 MM	211	return;
1e9b51c2 MM	212
a93751ca MM	213	err = trace->read(this_tracer, at, &bts);
	214	if (err < 0)
	215	return;
1e9b51c2	216
a93751ca MM	217	switch (bts.qualifier) {
a93751ca MM	218	case BTS_BRANCH:
b1818748	219	trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to);
a93751ca MM	220	break;
a93751ca MM	221	}
1e9b51c2 MM	222	}
1e9b51c2 MM	223
5c5317de MM	224	/*
	225	* Collect the trace on the current cpu and write it into the ftrace buffer.
	226	*
2d542cf3	227	* pre: bts_tracer_lock must be locked
5c5317de	228	*/
1e9b51c2 MM	229	static void trace_bts_cpu(void *arg)
	230	{
	231	struct trace_array tr = (struct trace_array ) arg;
a93751ca MM	232	const struct bts_trace *trace;
a93751ca MM	233	unsigned char *at;
1e9b51c2	234
b1818748	235	if (unlikely(!tr))
1e9b51c2 MM	236	return;
1e9b51c2 MM	237
5c5317de MM	238	if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
	239	return;
	240
b1818748 MM	241	if (unlikely(!this_tracer))
	242	return;
	243
a93751ca MM	244	ds_suspend_bts(this_tracer);
	245	trace = ds_read_bts(this_tracer);
	246	if (!trace)
1e9b51c2 MM	247	goto out;
1e9b51c2 MM	248
a93751ca MM	249	for (at = trace->ds.top; (void *)at < trace->ds.end;
a93751ca MM	250	at += trace->ds.size)
b1818748	251	trace_bts_at(trace, at);
1e9b51c2	252
a93751ca MM	253	for (at = trace->ds.begin; (void *)at < trace->ds.top;
a93751ca MM	254	at += trace->ds.size)
b1818748	255	trace_bts_at(trace, at);
1e9b51c2 MM	256
1e9b51c2 MM	257	out:
a93751ca	258	ds_resume_bts(this_tracer);
1e9b51c2 MM	259	}
	260
	261	static void trace_bts_prepare(struct trace_iterator *iter)
	262	{
2d542cf3	263	spin_lock(&bts_tracer_lock);
5c5317de MM	264
5c5317de MM	265	on_each_cpu(trace_bts_cpu, iter->tr, 1);
1e9b51c2	266
2d542cf3	267	spin_unlock(&bts_tracer_lock);
1e9b51c2 MM	268	}
1e9b51c2 MM	269
e23b8ad8 MM	270	static void trace_bts_close(struct trace_iterator *iter)
	271	{
	272	tracing_reset_online_cpus(iter->tr);
	273	}
	274
b1818748 MM	275	void trace_hw_branch_oops(void)
b1818748 MM	276	{
2d542cf3	277	spin_lock(&bts_tracer_lock);
b1818748 MM	278
	279	trace_bts_cpu(hw_branch_trace);
	280
2d542cf3	281	spin_unlock(&bts_tracer_lock);
b1818748 MM	282	}
b1818748 MM	283
1e9b51c2 MM	284	struct tracer bts_tracer __read_mostly =
1e9b51c2 MM	285	{
a93751ca	286	.name = "hw-branch-tracer",
1e9b51c2	287	.init = bts_trace_init,
5c5317de	288	.reset = bts_trace_reset,
1e9b51c2 MM	289	.print_header = bts_trace_print_header,
	290	.print_line = bts_trace_print_line,
	291	.start = bts_trace_start,
	292	.stop = bts_trace_stop,
e23b8ad8 MM	293	.open = trace_bts_prepare,
e23b8ad8 MM	294	.close = trace_bts_close
1e9b51c2 MM	295	};
	296
	297	__init static int init_bts_trace(void)
	298	{
5e01cb69	299	register_hotcpu_notifier(&bts_hotcpu_notifier);
1e9b51c2 MM	300	return register_tracer(&bts_tracer);
	301	}
	302	device_initcall(init_bts_trace);