aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/trace/trace_bts.c
blob: 23b76e4690efc824198aedee6bbbb1d4fbcc6bda (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
/*
 * BTS tracer
 *
 * Copyright (C) 2008 Markus Metzger <markus.t.metzger@gmail.com>
 *
 */

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

#include <asm/ds.h>

#include "trace.h"


#define SIZEOF_BTS (1 << 13)

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())


/*
 * Information to interpret a BTS record.
 * This will go into an in-kernel BTS interface.
 */
static unsigned char sizeof_field;
static unsigned long debugctl_mask;

#define sizeof_bts (3 * sizeof_field)

static void bts_trace_cpuinit(struct cpuinfo_x86 *c)
{
	switch (c->x86) {
	case 0x6:
		switch (c->x86_model) {
		case 0x0 ... 0xC:
			break;
		case 0xD:
		case 0xE: /* Pentium M */
			sizeof_field = sizeof(long);
			debugctl_mask = (1<<6)|(1<<7);
			break;
		default:
			sizeof_field = 8;
			debugctl_mask = (1<<6)|(1<<7);
			break;
		}
		break;
	case 0xF:
		switch (c->x86_model) {
		case 0x0:
		case 0x1:
		case 0x2: /* Netburst */
			sizeof_field = sizeof(long);
			debugctl_mask = (1<<2)|(1<<3);
			break;
		default:
			/* sorry, don't know about them */
			break;
		}
		break;
	default:
		/* sorry, don't know about them */
		break;
	}
}

static inline void bts_enable(void)
{
	unsigned long debugctl;

	rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
	wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl | debugctl_mask);
}

static inline void bts_disable(void)
{
	unsigned long debugctl;

	rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
	wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl & ~debugctl_mask);
}

static void bts_trace_reset(struct trace_array *tr)
{
	int cpu;

	tr->time_start = ftrace_now(tr->cpu);

	for_each_online_cpu(cpu)
		tracing_reset(tr, cpu);
}

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

	bts_enable();
}

static void bts_trace_start(struct trace_array *tr)
{
	int cpu;

	bts_trace_reset(tr);

	for_each_cpu_mask(cpu, cpu_possible_map)
		smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
}

static void bts_trace_stop_cpu(void *arg)
{
	if (this_tracer) {
		bts_disable();

		ds_release_bts(this_tracer);
		this_tracer = NULL;
	}
}

static void bts_trace_stop(struct trace_array *tr)
{
	int cpu;

	for_each_cpu_mask(cpu, cpu_possible_map)
		smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
}

static int bts_trace_init(struct trace_array *tr)
{
	bts_trace_cpuinit(&boot_cpu_data);
	bts_trace_reset(tr);
	bts_trace_start(tr);

	return 0;
}

static void bts_trace_print_header(struct seq_file *m)
{
#ifdef __i386__
	seq_puts(m, "# CPU#    FROM           TO     FUNCTION\n");
	seq_puts(m, "#  |       |             |         |\n");
#else
	seq_puts(m,
		 "# CPU#        FROM                   TO         FUNCTION\n");
	seq_puts(m,
		 "#  |           |                     |             |\n");
#endif
}

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 bts_entry *it;

	trace_assign_type(it, entry);

	if (entry->type == TRACE_BTS) {
		int ret;
#ifdef CONFIG_KALLSYMS
		char function[KSYM_SYMBOL_LEN];
		sprint_symbol(function, it->from);
#else
		char *function = "<unknown>";
#endif

		ret = trace_seq_printf(seq, "%4d  0x%lx -> 0x%lx [%s]\n",
				       entry->cpu, it->from, it->to, function);
		if (!ret)
			return TRACE_TYPE_PARTIAL_LINE;;
		return TRACE_TYPE_HANDLED;
	}
	return TRACE_TYPE_UNHANDLED;
}

void trace_bts(struct trace_array *tr, unsigned long from, unsigned long to)
{
	struct ring_buffer_event *event;
	struct bts_entry *entry;
	unsigned long irq;

	event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq);
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
	tracing_generic_entry_update(&entry->ent, 0, from);
	entry->ent.type = TRACE_BTS;
	entry->ent.cpu = smp_processor_id();
	entry->from = from;
	entry->to   = to;
	ring_buffer_unlock_commit(tr->buffer, event, irq);
}

static void trace_bts_at(struct trace_array *tr, size_t index)
{
	const void *raw = NULL;
	unsigned long from, to;
	int err;

	err = ds_access_bts(this_tracer, index, &raw);
	if (err < 0)
		return;

	from = *(const unsigned long *)raw;
	to = *(const unsigned long *)((const char *)raw + sizeof_field);

	trace_bts(tr, from, to);
}

static void trace_bts_cpu(void *arg)
{
	struct trace_array *tr = (struct trace_array *) arg;
	size_t index = 0, end = 0, i;
	int err;

	if (!this_tracer)
		return;

	bts_disable();

	err = ds_get_bts_index(this_tracer, &index);
	if (err < 0)
		goto out;

	err = ds_get_bts_end(this_tracer, &end);
	if (err < 0)
		goto out;

	for (i = index; i < end; i++)
		trace_bts_at(tr, i);

	for (i = 0; i < index; i++)
		trace_bts_at(tr, i);

out:
	bts_enable();
}

static void trace_bts_prepare(struct trace_iterator *iter)
{
	int cpu;

	for_each_cpu_mask(cpu, cpu_possible_map)
		smp_call_function_single(cpu, trace_bts_cpu, iter->tr, 1);
}

struct tracer bts_tracer __read_mostly =
{
	.name		= "bts",
	.init		= bts_trace_init,
	.reset		= bts_trace_stop,
	.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);