[WATCHDOG] davinci: use clock framework for timer frequency
[linux-ginger.git] / kernel / trace / trace_hw_branches.c
blobca7d7c4d0c2aef41b74585996001d993ff4505e2
1 /*
2 * h/w branch tracer for x86 based on BTS
4 * Copyright (C) 2008-2009 Intel Corporation.
5 * Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009
6 */
7 #include <linux/kallsyms.h>
8 #include <linux/debugfs.h>
9 #include <linux/ftrace.h>
10 #include <linux/module.h>
11 #include <linux/cpu.h>
12 #include <linux/smp.h>
13 #include <linux/fs.h>
15 #include <asm/ds.h>
17 #include "trace_output.h"
18 #include "trace.h"
21 #define BTS_BUFFER_SIZE (1 << 13)
23 static DEFINE_PER_CPU(struct bts_tracer *, tracer);
24 static DEFINE_PER_CPU(unsigned char[BTS_BUFFER_SIZE], buffer);
26 #define this_tracer per_cpu(tracer, smp_processor_id())
28 static int trace_hw_branches_enabled __read_mostly;
29 static int trace_hw_branches_suspended __read_mostly;
30 static struct trace_array *hw_branch_trace __read_mostly;
33 static void bts_trace_init_cpu(int cpu)
35 per_cpu(tracer, cpu) =
36 ds_request_bts_cpu(cpu, per_cpu(buffer, cpu), BTS_BUFFER_SIZE,
37 NULL, (size_t)-1, BTS_KERNEL);
39 if (IS_ERR(per_cpu(tracer, cpu)))
40 per_cpu(tracer, cpu) = NULL;
43 static int bts_trace_init(struct trace_array *tr)
45 int cpu;
47 hw_branch_trace = tr;
48 trace_hw_branches_enabled = 0;
50 get_online_cpus();
51 for_each_online_cpu(cpu) {
52 bts_trace_init_cpu(cpu);
54 if (likely(per_cpu(tracer, cpu)))
55 trace_hw_branches_enabled = 1;
57 trace_hw_branches_suspended = 0;
58 put_online_cpus();
60 /* If we could not enable tracing on a single cpu, we fail. */
61 return trace_hw_branches_enabled ? 0 : -EOPNOTSUPP;
64 static void bts_trace_reset(struct trace_array *tr)
66 int cpu;
68 get_online_cpus();
69 for_each_online_cpu(cpu) {
70 if (likely(per_cpu(tracer, cpu))) {
71 ds_release_bts(per_cpu(tracer, cpu));
72 per_cpu(tracer, cpu) = NULL;
75 trace_hw_branches_enabled = 0;
76 trace_hw_branches_suspended = 0;
77 put_online_cpus();
80 static void bts_trace_start(struct trace_array *tr)
82 int cpu;
84 get_online_cpus();
85 for_each_online_cpu(cpu)
86 if (likely(per_cpu(tracer, cpu)))
87 ds_resume_bts(per_cpu(tracer, cpu));
88 trace_hw_branches_suspended = 0;
89 put_online_cpus();
92 static void bts_trace_stop(struct trace_array *tr)
94 int cpu;
96 get_online_cpus();
97 for_each_online_cpu(cpu)
98 if (likely(per_cpu(tracer, cpu)))
99 ds_suspend_bts(per_cpu(tracer, cpu));
100 trace_hw_branches_suspended = 1;
101 put_online_cpus();
104 static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
105 unsigned long action, void *hcpu)
107 int cpu = (long)hcpu;
109 switch (action) {
110 case CPU_ONLINE:
111 case CPU_DOWN_FAILED:
112 /* The notification is sent with interrupts enabled. */
113 if (trace_hw_branches_enabled) {
114 bts_trace_init_cpu(cpu);
116 if (trace_hw_branches_suspended &&
117 likely(per_cpu(tracer, cpu)))
118 ds_suspend_bts(per_cpu(tracer, cpu));
120 break;
122 case CPU_DOWN_PREPARE:
123 /* The notification is sent with interrupts enabled. */
124 if (likely(per_cpu(tracer, cpu))) {
125 ds_release_bts(per_cpu(tracer, cpu));
126 per_cpu(tracer, cpu) = NULL;
130 return NOTIFY_DONE;
133 static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
134 .notifier_call = bts_hotcpu_handler
137 static void bts_trace_print_header(struct seq_file *m)
139 seq_puts(m, "# CPU# TO <- FROM\n");
142 static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
144 unsigned long symflags = TRACE_ITER_SYM_OFFSET;
145 struct trace_entry *entry = iter->ent;
146 struct trace_seq *seq = &iter->seq;
147 struct hw_branch_entry *it;
149 trace_assign_type(it, entry);
151 if (entry->type == TRACE_HW_BRANCHES) {
152 if (trace_seq_printf(seq, "%4d ", iter->cpu) &&
153 seq_print_ip_sym(seq, it->to, symflags) &&
154 trace_seq_printf(seq, "\t <- ") &&
155 seq_print_ip_sym(seq, it->from, symflags) &&
156 trace_seq_printf(seq, "\n"))
157 return TRACE_TYPE_HANDLED;
158 return TRACE_TYPE_PARTIAL_LINE;;
160 return TRACE_TYPE_UNHANDLED;
163 void trace_hw_branch(u64 from, u64 to)
165 struct ftrace_event_call *call = &event_hw_branch;
166 struct trace_array *tr = hw_branch_trace;
167 struct ring_buffer_event *event;
168 struct hw_branch_entry *entry;
169 unsigned long irq1;
170 int cpu;
172 if (unlikely(!tr))
173 return;
175 if (unlikely(!trace_hw_branches_enabled))
176 return;
178 local_irq_save(irq1);
179 cpu = raw_smp_processor_id();
180 if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
181 goto out;
183 event = trace_buffer_lock_reserve(tr, TRACE_HW_BRANCHES,
184 sizeof(*entry), 0, 0);
185 if (!event)
186 goto out;
187 entry = ring_buffer_event_data(event);
188 tracing_generic_entry_update(&entry->ent, 0, from);
189 entry->ent.type = TRACE_HW_BRANCHES;
190 entry->from = from;
191 entry->to = to;
192 if (!filter_check_discard(call, entry, tr->buffer, event))
193 trace_buffer_unlock_commit(tr, event, 0, 0);
195 out:
196 atomic_dec(&tr->data[cpu]->disabled);
197 local_irq_restore(irq1);
200 static void trace_bts_at(const struct bts_trace *trace, void *at)
202 struct bts_struct bts;
203 int err = 0;
205 WARN_ON_ONCE(!trace->read);
206 if (!trace->read)
207 return;
209 err = trace->read(this_tracer, at, &bts);
210 if (err < 0)
211 return;
213 switch (bts.qualifier) {
214 case BTS_BRANCH:
215 trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to);
216 break;
221 * Collect the trace on the current cpu and write it into the ftrace buffer.
223 * pre: tracing must be suspended on the current cpu
225 static void trace_bts_cpu(void *arg)
227 struct trace_array *tr = (struct trace_array *)arg;
228 const struct bts_trace *trace;
229 unsigned char *at;
231 if (unlikely(!tr))
232 return;
234 if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
235 return;
237 if (unlikely(!this_tracer))
238 return;
240 trace = ds_read_bts(this_tracer);
241 if (!trace)
242 return;
244 for (at = trace->ds.top; (void *)at < trace->ds.end;
245 at += trace->ds.size)
246 trace_bts_at(trace, at);
248 for (at = trace->ds.begin; (void *)at < trace->ds.top;
249 at += trace->ds.size)
250 trace_bts_at(trace, at);
253 static void trace_bts_prepare(struct trace_iterator *iter)
255 int cpu;
257 get_online_cpus();
258 for_each_online_cpu(cpu)
259 if (likely(per_cpu(tracer, cpu)))
260 ds_suspend_bts(per_cpu(tracer, cpu));
262 * We need to collect the trace on the respective cpu since ftrace
263 * implicitly adds the record for the current cpu.
264 * Once that is more flexible, we could collect the data from any cpu.
266 on_each_cpu(trace_bts_cpu, iter->tr, 1);
268 for_each_online_cpu(cpu)
269 if (likely(per_cpu(tracer, cpu)))
270 ds_resume_bts(per_cpu(tracer, cpu));
271 put_online_cpus();
274 static void trace_bts_close(struct trace_iterator *iter)
276 tracing_reset_online_cpus(iter->tr);
279 void trace_hw_branch_oops(void)
281 if (this_tracer) {
282 ds_suspend_bts_noirq(this_tracer);
283 trace_bts_cpu(hw_branch_trace);
284 ds_resume_bts_noirq(this_tracer);
288 struct tracer bts_tracer __read_mostly =
290 .name = "hw-branch-tracer",
291 .init = bts_trace_init,
292 .reset = bts_trace_reset,
293 .print_header = bts_trace_print_header,
294 .print_line = bts_trace_print_line,
295 .start = bts_trace_start,
296 .stop = bts_trace_stop,
297 .open = trace_bts_prepare,
298 .close = trace_bts_close,
299 #ifdef CONFIG_FTRACE_SELFTEST
300 .selftest = trace_selftest_startup_hw_branches,
301 #endif /* CONFIG_FTRACE_SELFTEST */
304 __init static int init_bts_trace(void)
306 register_hotcpu_notifier(&bts_hotcpu_notifier);
307 return register_tracer(&bts_tracer);
309 device_initcall(init_bts_trace);