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>
17 #include "trace_output.h"
20 #define SIZEOF_BTS (1 << 13)
22 static DEFINE_PER_CPU(struct bts_tracer *, tracer);
23 static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
25 #define this_tracer per_cpu(tracer, smp_processor_id())
26 #define this_buffer per_cpu(buffer, smp_processor_id())
29 static void bts_trace_start_cpu(void *arg)
32 ds_release_bts(this_tracer);
35 ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
36 /* ovfl = */ NULL, /* th = */ (size_t)-1,
38 if (IS_ERR(this_tracer)) {
44 static void bts_trace_start(struct trace_array *tr)
48 tracing_reset_online_cpus(tr);
50 for_each_cpu(cpu, cpu_possible_mask)
51 smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
54 static void bts_trace_stop_cpu(void *arg)
57 ds_release_bts(this_tracer);
62 static void bts_trace_stop(struct trace_array *tr)
66 for_each_cpu(cpu, cpu_possible_mask)
67 smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
70 static int bts_trace_init(struct trace_array *tr)
72 tracing_reset_online_cpus(tr);
78 static void bts_trace_print_header(struct seq_file *m)
81 "# CPU# FROM TO FUNCTION\n");
86 static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
88 struct trace_entry *entry = iter->ent;
89 struct trace_seq *seq = &iter->seq;
90 struct hw_branch_entry *it;
92 trace_assign_type(it, entry);
94 if (entry->type == TRACE_HW_BRANCHES) {
95 if (trace_seq_printf(seq, "%4d ", entry->cpu) &&
96 trace_seq_printf(seq, "0x%016llx -> 0x%016llx ",
99 seq_print_ip_sym(seq, it->from, /* sym_flags = */ 0)) &&
100 trace_seq_printf(seq, "\n"))
101 return TRACE_TYPE_HANDLED;
102 return TRACE_TYPE_PARTIAL_LINE;;
104 return TRACE_TYPE_UNHANDLED;
107 void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
109 struct ring_buffer_event *event;
110 struct hw_branch_entry *entry;
113 event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq);
116 entry = ring_buffer_event_data(event);
117 tracing_generic_entry_update(&entry->ent, 0, from);
118 entry->ent.type = TRACE_HW_BRANCHES;
119 entry->ent.cpu = smp_processor_id();
122 ring_buffer_unlock_commit(tr->buffer, event, irq);
125 static void trace_bts_at(struct trace_array *tr,
126 const struct bts_trace *trace, void *at)
128 struct bts_struct bts;
131 WARN_ON_ONCE(!trace->read);
135 err = trace->read(this_tracer, at, &bts);
139 switch (bts.qualifier) {
141 trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
146 static void trace_bts_cpu(void *arg)
148 struct trace_array *tr = (struct trace_array *) arg;
149 const struct bts_trace *trace;
155 ds_suspend_bts(this_tracer);
156 trace = ds_read_bts(this_tracer);
160 for (at = trace->ds.top; (void *)at < trace->ds.end;
161 at += trace->ds.size)
162 trace_bts_at(tr, trace, at);
164 for (at = trace->ds.begin; (void *)at < trace->ds.top;
165 at += trace->ds.size)
166 trace_bts_at(tr, trace, at);
169 ds_resume_bts(this_tracer);
172 static void trace_bts_prepare(struct trace_iterator *iter)
176 for_each_cpu(cpu, cpu_possible_mask)
177 smp_call_function_single(cpu, trace_bts_cpu, iter->tr, 1);
180 struct tracer bts_tracer __read_mostly =
182 .name = "hw-branch-tracer",
183 .init = bts_trace_init,
184 .reset = bts_trace_stop,
185 .print_header = bts_trace_print_header,
186 .print_line = bts_trace_print_line,
187 .start = bts_trace_start,
188 .stop = bts_trace_stop,
189 .open = trace_bts_prepare
192 __init static int init_bts_trace(void)
194 return register_tracer(&bts_tracer);
196 device_initcall(init_bts_trace);