/*
- * h/w branch tracer for x86 based on bts
- *
- * Copyright (C) 2008 Markus Metzger <markus.t.metzger@gmail.com>
+ * h/w branch tracer for x86 based on BTS
*
+ * Copyright (C) 2008-2009 Intel Corporation.
+ * Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009
*/
-
-#include <linux/module.h>
-#include <linux/fs.h>
+#include <linux/kallsyms.h>
#include <linux/debugfs.h>
#include <linux/ftrace.h>
-#include <linux/kallsyms.h>
+#include <linux/module.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/fs.h>
#include <asm/ds.h>
+#include "trace_output.h"
#include "trace.h"
-#define SIZEOF_BTS (1 << 13)
+#define BTS_BUFFER_SIZE (1 << 13)
static DEFINE_PER_CPU(struct bts_tracer *, tracer);
-static DEFINE_PER_CPU(unsigned char[SIZEOF_BTS], buffer);
+static DEFINE_PER_CPU(unsigned char[BTS_BUFFER_SIZE], buffer);
#define this_tracer per_cpu(tracer, smp_processor_id())
-#define this_buffer per_cpu(buffer, smp_processor_id())
+static int trace_hw_branches_enabled __read_mostly;
+static int trace_hw_branches_suspended __read_mostly;
+static struct trace_array *hw_branch_trace __read_mostly;
-static void bts_trace_start_cpu(void *arg)
+
+static void bts_trace_init_cpu(int cpu)
{
- if (this_tracer)
- ds_release_bts(this_tracer);
+ per_cpu(tracer, cpu) =
+ ds_request_bts_cpu(cpu, per_cpu(buffer, cpu), BTS_BUFFER_SIZE,
+ NULL, (size_t)-1, BTS_KERNEL);
- 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;
- }
+ if (IS_ERR(per_cpu(tracer, cpu)))
+ per_cpu(tracer, cpu) = NULL;
}
-static void bts_trace_start(struct trace_array *tr)
+static int bts_trace_init(struct trace_array *tr)
{
int cpu;
- tracing_reset_online_cpus(tr);
+ hw_branch_trace = tr;
+ trace_hw_branches_enabled = 0;
+
+ get_online_cpus();
+ for_each_online_cpu(cpu) {
+ bts_trace_init_cpu(cpu);
+
+ if (likely(per_cpu(tracer, cpu)))
+ trace_hw_branches_enabled = 1;
+ }
+ trace_hw_branches_suspended = 0;
+ put_online_cpus();
- for_each_cpu(cpu, cpu_possible_mask)
- smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1);
+ /* If we could not enable tracing on a single cpu, we fail. */
+ return trace_hw_branches_enabled ? 0 : -EOPNOTSUPP;
}
-static void bts_trace_stop_cpu(void *arg)
+static void bts_trace_reset(struct trace_array *tr)
{
- if (this_tracer) {
- ds_release_bts(this_tracer);
- this_tracer = NULL;
+ int cpu;
+
+ get_online_cpus();
+ for_each_online_cpu(cpu) {
+ if (likely(per_cpu(tracer, cpu))) {
+ ds_release_bts(per_cpu(tracer, cpu));
+ per_cpu(tracer, cpu) = NULL;
+ }
}
+ trace_hw_branches_enabled = 0;
+ trace_hw_branches_suspended = 0;
+ put_online_cpus();
+}
+
+static void bts_trace_start(struct trace_array *tr)
+{
+ int cpu;
+
+ get_online_cpus();
+ for_each_online_cpu(cpu)
+ if (likely(per_cpu(tracer, cpu)))
+ ds_resume_bts(per_cpu(tracer, cpu));
+ trace_hw_branches_suspended = 0;
+ put_online_cpus();
}
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);
+ get_online_cpus();
+ for_each_online_cpu(cpu)
+ if (likely(per_cpu(tracer, cpu)))
+ ds_suspend_bts(per_cpu(tracer, cpu));
+ trace_hw_branches_suspended = 1;
+ put_online_cpus();
}
-static int bts_trace_init(struct trace_array *tr)
+static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
{
- tracing_reset_online_cpus(tr);
- bts_trace_start(tr);
+ int cpu = (long)hcpu;
+
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_DOWN_FAILED:
+ /* The notification is sent with interrupts enabled. */
+ if (trace_hw_branches_enabled) {
+ bts_trace_init_cpu(cpu);
+
+ if (trace_hw_branches_suspended &&
+ likely(per_cpu(tracer, cpu)))
+ ds_suspend_bts(per_cpu(tracer, cpu));
+ }
+ break;
- return 0;
+ case CPU_DOWN_PREPARE:
+ /* The notification is sent with interrupts enabled. */
+ if (likely(per_cpu(tracer, cpu))) {
+ ds_release_bts(per_cpu(tracer, cpu));
+ per_cpu(tracer, cpu) = NULL;
+ }
+ }
+
+ return NOTIFY_DONE;
}
+static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
+ .notifier_call = bts_hotcpu_handler
+};
+
static void bts_trace_print_header(struct seq_file *m)
{
- seq_puts(m,
- "# CPU# FROM TO FUNCTION\n");
- seq_puts(m,
- "# | | | |\n");
+ seq_puts(m, "# CPU# TO <- FROM\n");
}
static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
{
+ unsigned long symflags = TRACE_ITER_SYM_OFFSET;
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)) &&
+ if (trace_seq_printf(seq, "%4d ", iter->cpu) &&
+ seq_print_ip_sym(seq, it->to, symflags) &&
+ trace_seq_printf(seq, "\t <- ") &&
+ seq_print_ip_sym(seq, it->from, symflags) &&
trace_seq_printf(seq, "\n"))
return TRACE_TYPE_HANDLED;
- return TRACE_TYPE_PARTIAL_LINE;;
+ return TRACE_TYPE_PARTIAL_LINE;
}
return TRACE_TYPE_UNHANDLED;
}
-void trace_hw_branch(struct trace_array *tr, u64 from, u64 to)
+void trace_hw_branch(u64 from, u64 to)
{
+ struct ftrace_event_call *call = &event_hw_branch;
+ struct trace_array *tr = hw_branch_trace;
struct ring_buffer_event *event;
+ struct ring_buffer *buf;
struct hw_branch_entry *entry;
- unsigned long irq;
+ unsigned long irq1;
+ int cpu;
- event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq);
- if (!event)
+ if (unlikely(!tr))
+ return;
+
+ if (unlikely(!trace_hw_branches_enabled))
return;
+
+ local_irq_save(irq1);
+ cpu = raw_smp_processor_id();
+ if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
+ goto out;
+
+ buf = tr->buffer;
+ event = trace_buffer_lock_reserve(buf, TRACE_HW_BRANCHES,
+ sizeof(*entry), 0, 0);
+ if (!event)
+ goto out;
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);
+ if (!filter_check_discard(call, entry, buf, event))
+ trace_buffer_unlock_commit(buf, event, 0, 0);
+
+ out:
+ atomic_dec(&tr->data[cpu]->disabled);
+ local_irq_restore(irq1);
}
-static void trace_bts_at(struct trace_array *tr,
- const struct bts_trace *trace, void *at)
+static void trace_bts_at(const struct bts_trace *trace, void *at)
{
struct bts_struct bts;
int err = 0;
switch (bts.qualifier) {
case BTS_BRANCH:
- trace_hw_branch(tr, bts.variant.lbr.from, bts.variant.lbr.to);
+ trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to);
break;
}
}
+/*
+ * Collect the trace on the current cpu and write it into the ftrace buffer.
+ *
+ * pre: tracing must be suspended on the current cpu
+ */
static void trace_bts_cpu(void *arg)
{
- struct trace_array *tr = (struct trace_array *) arg;
+ struct trace_array *tr = (struct trace_array *)arg;
const struct bts_trace *trace;
unsigned char *at;
- if (!this_tracer)
+ if (unlikely(!tr))
+ return;
+
+ if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
+ return;
+
+ if (unlikely(!this_tracer))
return;
- ds_suspend_bts(this_tracer);
trace = ds_read_bts(this_tracer);
if (!trace)
- goto out;
+ return;
for (at = trace->ds.top; (void *)at < trace->ds.end;
at += trace->ds.size)
- trace_bts_at(tr, trace, at);
+ trace_bts_at(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);
+ trace_bts_at(trace, at);
}
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);
+ get_online_cpus();
+ for_each_online_cpu(cpu)
+ if (likely(per_cpu(tracer, cpu)))
+ ds_suspend_bts(per_cpu(tracer, cpu));
+ /*
+ * We need to collect the trace on the respective cpu since ftrace
+ * implicitly adds the record for the current cpu.
+ * Once that is more flexible, we could collect the data from any cpu.
+ */
+ on_each_cpu(trace_bts_cpu, iter->tr, 1);
+
+ for_each_online_cpu(cpu)
+ if (likely(per_cpu(tracer, cpu)))
+ ds_resume_bts(per_cpu(tracer, cpu));
+ put_online_cpus();
+}
+
+static void trace_bts_close(struct trace_iterator *iter)
+{
+ tracing_reset_online_cpus(iter->tr);
+}
+
+void trace_hw_branch_oops(void)
+{
+ if (this_tracer) {
+ ds_suspend_bts_noirq(this_tracer);
+ trace_bts_cpu(hw_branch_trace);
+ ds_resume_bts_noirq(this_tracer);
+ }
}
struct tracer bts_tracer __read_mostly =
{
.name = "hw-branch-tracer",
.init = bts_trace_init,
- .reset = bts_trace_stop,
+ .reset = bts_trace_reset,
.print_header = bts_trace_print_header,
.print_line = bts_trace_print_line,
.start = bts_trace_start,
.stop = bts_trace_stop,
- .open = trace_bts_prepare
+ .open = trace_bts_prepare,
+ .close = trace_bts_close,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_hw_branches,
+#endif /* CONFIG_FTRACE_SELFTEST */
};
__init static int init_bts_trace(void)
{
+ register_hotcpu_notifier(&bts_hotcpu_notifier);
return register_tracer(&bts_tracer);
}
device_initcall(init_bts_trace);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff