2 * h/w branch tracer for x86 based on bts
4 * Copyright (C) 2008 Markus Metzger <markus.t.metzger@gmail.com>
8 #include <linux/module.h>
10 #include <linux/debugfs.h>
11 #include <linux/ftrace.h>
12 #include <linux/kallsyms.h>
19 #define SIZEOF_BTS (1 << 13)
21 static DEFINE_PER_CPU(struct bts_tracer *, tracer);
22 static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
24 #define this_tracer per_cpu(tracer, smp_processor_id())
25 #define this_buffer per_cpu(buffer, smp_processor_id())
28 static void bts_trace_reset(struct trace_array *tr)
32 tr->time_start = ftrace_now(tr->cpu);
34 for_each_online_cpu(cpu)
35 tracing_reset(tr, cpu);
38 static void bts_trace_start_cpu(void *arg)
41 ds_release_bts(this_tracer);
44 ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
45 /* ovfl = */ NULL, /* th = */ (size_t)-1,
47 if (IS_ERR(this_tracer)) {
53 static void bts_trace_start(struct trace_array *tr)
59 for_each_cpu_mask(cpu, cpu_possible_map)
60 smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
63 static void bts_trace_stop_cpu(void *arg)
66 ds_release_bts(this_tracer);
71 static void bts_trace_stop(struct trace_array *tr)
75 for_each_cpu_mask(cpu, cpu_possible_map)
76 smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
79 static int bts_trace_init(struct trace_array *tr)
87 static void bts_trace_print_header(struct seq_file *m)
90 "# CPU# FROM TO FUNCTION\n");
95 static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
97 struct trace_entry *entry = iter->ent;
98 struct trace_seq *seq = &iter->seq;
99 struct hw_branch_entry *it;
101 trace_assign_type(it, entry);
103 if (entry->type == TRACE_HW_BRANCHES) {
104 if (trace_seq_printf(seq, "%4d ", entry->cpu) &&
105 trace_seq_printf(seq, "0x%016llx -> 0x%016llx ",
108 seq_print_ip_sym(seq, it->from, /* sym_flags = */ 0)) &&
109 trace_seq_printf(seq, "\n"))
110 return TRACE_TYPE_HANDLED;
111 return TRACE_TYPE_PARTIAL_LINE;;
113 return TRACE_TYPE_UNHANDLED;
116 void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
118 struct ring_buffer_event *event;
119 struct hw_branch_entry *entry;
122 event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq);
125 entry = ring_buffer_event_data(event);
126 tracing_generic_entry_update(&entry->ent, 0, from);
127 entry->ent.type = TRACE_HW_BRANCHES;
128 entry->ent.cpu = smp_processor_id();
131 ring_buffer_unlock_commit(tr->buffer, event, irq);
134 static void trace_bts_at(struct trace_array *tr,
135 const struct bts_trace *trace, void *at)
137 struct bts_struct bts;
140 WARN_ON_ONCE(!trace->read);
144 err = trace->read(this_tracer, at, &bts);
148 switch (bts.qualifier) {
150 trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
155 static void trace_bts_cpu(void *arg)
157 struct trace_array *tr = (struct trace_array *) arg;
158 const struct bts_trace *trace;
164 ds_suspend_bts(this_tracer);
165 trace = ds_read_bts(this_tracer);
169 for (at = trace->ds.top; (void *)at < trace->ds.end;
170 at += trace->ds.size)
171 trace_bts_at(tr, trace, at);
173 for (at = trace->ds.begin; (void *)at < trace->ds.top;
174 at += trace->ds.size)
175 trace_bts_at(tr, trace, at);
178 ds_resume_bts(this_tracer);
181 static void trace_bts_prepare(struct trace_iterator *iter)
185 for_each_cpu_mask(cpu, cpu_possible_map)
186 smp_call_function_single(cpu, trace_bts_cpu, iter->tr, 1);
189 struct tracer bts_tracer __read_mostly =
191 .name = "hw-branch-tracer",
192 .init = bts_trace_init,
193 .reset = bts_trace_stop,
194 .print_header = bts_trace_print_header,
195 .print_line = bts_trace_print_line,
196 .start = bts_trace_start,
197 .stop = bts_trace_stop,
198 .open = trace_bts_prepare
201 __init static int init_bts_trace(void)
203 return register_tracer(&bts_tracer);
205 device_initcall(init_bts_trace);