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_start_cpu(void *arg)
31 ds_release_bts(this_tracer);
34 ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
35 /* ovfl = */ NULL, /* th = */ (size_t)-1,
37 if (IS_ERR(this_tracer)) {
43 static void bts_trace_start(struct trace_array *tr)
47 tracing_reset_online_cpus(tr);
49 for_each_cpu_mask(cpu, cpu_possible_map)
50 smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
53 static void bts_trace_stop_cpu(void *arg)
56 ds_release_bts(this_tracer);
61 static void bts_trace_stop(struct trace_array *tr)
65 for_each_cpu_mask(cpu, cpu_possible_map)
66 smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
69 static int bts_trace_init(struct trace_array *tr)
71 tracing_reset_online_cpus(tr);
77 static void bts_trace_print_header(struct seq_file *m)
80 "# CPU# FROM TO FUNCTION\n");
85 static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
87 struct trace_entry *entry = iter->ent;
88 struct trace_seq *seq = &iter->seq;
89 struct hw_branch_entry *it;
91 trace_assign_type(it, entry);
93 if (entry->type == TRACE_HW_BRANCHES) {
94 if (trace_seq_printf(seq, "%4d ", entry->cpu) &&
95 trace_seq_printf(seq, "0x%016llx -> 0x%016llx ",
98 seq_print_ip_sym(seq, it->from, /* sym_flags = */ 0)) &&
99 trace_seq_printf(seq, "\n"))
100 return TRACE_TYPE_HANDLED;
101 return TRACE_TYPE_PARTIAL_LINE;;
103 return TRACE_TYPE_UNHANDLED;
106 void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
108 struct ring_buffer_event *event;
109 struct hw_branch_entry *entry;
112 event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq);
115 entry = ring_buffer_event_data(event);
116 tracing_generic_entry_update(&entry->ent, 0, from);
117 entry->ent.type = TRACE_HW_BRANCHES;
118 entry->ent.cpu = smp_processor_id();
121 ring_buffer_unlock_commit(tr->buffer, event, irq);
124 static void trace_bts_at(struct trace_array *tr,
125 const struct bts_trace *trace, void *at)
127 struct bts_struct bts;
130 WARN_ON_ONCE(!trace->read);
134 err = trace->read(this_tracer, at, &bts);
138 switch (bts.qualifier) {
140 trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
145 static void trace_bts_cpu(void *arg)
147 struct trace_array *tr = (struct trace_array *) arg;
148 const struct bts_trace *trace;
154 ds_suspend_bts(this_tracer);
155 trace = ds_read_bts(this_tracer);
159 for (at = trace->ds.top; (void *)at < trace->ds.end;
160 at += trace->ds.size)
161 trace_bts_at(tr, trace, at);
163 for (at = trace->ds.begin; (void *)at < trace->ds.top;
164 at += trace->ds.size)
165 trace_bts_at(tr, trace, at);
168 ds_resume_bts(this_tracer);
171 static void trace_bts_prepare(struct trace_iterator *iter)
175 for_each_cpu_mask(cpu, cpu_possible_map)
176 smp_call_function_single(cpu, trace_bts_cpu, iter->tr, 1);
179 struct tracer bts_tracer __read_mostly =
181 .name = "hw-branch-tracer",
182 .init = bts_trace_init,
183 .reset = bts_trace_stop,
184 .print_header = bts_trace_print_header,
185 .print_line = bts_trace_print_line,
186 .start = bts_trace_start,
187 .stop = bts_trace_stop,
188 .open = trace_bts_prepare
191 __init static int init_bts_trace(void)
193 return register_tracer(&bts_tracer);
195 device_initcall(init_bts_trace);