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/*
* h/w branch tracer for x86 based on bts
*
* 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())
static void bts_trace_start_cpu(void *arg)
{
if (this_tracer)
ds_release_bts(this_tracer);
this_tracer =
ds_request_bts(/* task = */ NULL, this_buffer, SIZEOF_BTS,
/* ovfl = */ NULL, /* th = */ (size_t)-1,
BTS_KERNEL);
if (IS_ERR(this_tracer)) {
this_tracer = NULL;
return;
}
}
static void bts_trace_start(struct trace_array *tr)
{
int cpu;
tracing_reset_online_cpus(tr);
for_each_cpu(cpu, cpu_possible_mask)
smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
}
static void bts_trace_stop_cpu(void *arg)
{
if (this_tracer) {
ds_release_bts(this_tracer);
this_tracer = NULL;
}
}
static void bts_trace_stop(struct trace_array *tr)
{
int cpu;
for_each_cpu(cpu, cpu_possible_mask)
smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1);
}
static int bts_trace_init(struct trace_array *tr)
{
tracing_reset_online_cpus(tr);
bts_trace_start(tr);
return 0;
}
static void bts_trace_print_header(struct seq_file *m)
{
seq_puts(m,
"# CPU# FROM TO FUNCTION\n");
seq_puts(m,
"# | | | |\n");
}
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 hw_branch_entry *it;
trace_assign_type(it, entry);
if (entry->type == TRACE_HW_BRANCHES) {
if (trace_seq_printf(seq, "%4d ", entry->cpu) &&
trace_seq_printf(seq, "0x%016llx -> 0x%016llx ",
it->from, it->to) &&
(!it->from ||
seq_print_ip_sym(seq, it->from, /* sym_flags = */ 0)) &&
trace_seq_printf(seq, "\n"))
return TRACE_TYPE_HANDLED;
return TRACE_TYPE_PARTIAL_LINE;;
}
return TRACE_TYPE_UNHANDLED;
}
void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
{
struct ring_buffer_event *event;
struct hw_branch_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_HW_BRANCHES;
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,
const struct bts_trace *trace, void *at)
{
struct bts_struct bts;
int err = 0;
WARN_ON_ONCE(!trace->read);
if (!trace->read)
return;
err = trace->read(this_tracer, at, &bts);
if (err < 0)
return;
switch (bts.qualifier) {
case BTS_BRANCH:
trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
break;
}
}
static void trace_bts_cpu(void *arg)
{
struct trace_array *tr = (struct trace_array *) arg;
const struct bts_trace *trace;
unsigned char *at;
if (!this_tracer)
return;
ds_suspend_bts(this_tracer);
trace = ds_read_bts(this_tracer);
if (!trace)
goto out;
for (at = trace->ds.top; (void *)at < trace->ds.end;
at += trace->ds.size)
trace_bts_at(tr, trace, at);
for (at = trace->ds.begin; (void *)at < trace->ds.top;
at += trace->ds.size)
trace_bts_at(tr, trace, at);
out:
ds_resume_bts(this_tracer);
}
static void trace_bts_prepare(struct trace_iterator *iter)
{
int cpu;
for_each_cpu(cpu, cpu_possible_mask)
smp_call_function_single(cpu, trace_bts_cpu, iter->tr, 1);
}
struct tracer bts_tracer __read_mostly =
{
.name = "hw-branch-tracer",
.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);
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