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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /kernel/trace/trace_irqsoff.c
Initial import
Diffstat (limited to 'kernel/trace/trace_irqsoff.c')
-rw-r--r--kernel/trace/trace_irqsoff.c764
1 files changed, 764 insertions, 0 deletions
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
new file mode 100644
index 000000000..8523ea345
--- /dev/null
+++ b/kernel/trace/trace_irqsoff.c
@@ -0,0 +1,764 @@
+/*
+ * trace irqs off critical timings
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ * From code in the latency_tracer, that is:
+ *
+ * Copyright (C) 2004-2006 Ingo Molnar
+ * Copyright (C) 2004 Nadia Yvette Chambers
+ */
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/ftrace.h>
+
+#include "trace.h"
+
+static struct trace_array *irqsoff_trace __read_mostly;
+static int tracer_enabled __read_mostly;
+
+static DEFINE_PER_CPU(int, tracing_cpu);
+
+static DEFINE_RAW_SPINLOCK(max_trace_lock);
+
+enum {
+ TRACER_IRQS_OFF = (1 << 1),
+ TRACER_PREEMPT_OFF = (1 << 2),
+};
+
+static int trace_type __read_mostly;
+
+static int save_flags;
+static bool function_enabled;
+
+static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
+static int start_irqsoff_tracer(struct trace_array *tr, int graph);
+
+#ifdef CONFIG_PREEMPT_TRACER
+static inline int
+preempt_trace(void)
+{
+ return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
+}
+#else
+# define preempt_trace() (0)
+#endif
+
+#ifdef CONFIG_IRQSOFF_TRACER
+static inline int
+irq_trace(void)
+{
+ return ((trace_type & TRACER_IRQS_OFF) &&
+ irqs_disabled());
+}
+#else
+# define irq_trace() (0)
+#endif
+
+#define TRACE_DISPLAY_GRAPH 1
+
+static struct tracer_opt trace_opts[] = {
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ /* display latency trace as call graph */
+ { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
+#endif
+ { } /* Empty entry */
+};
+
+static struct tracer_flags tracer_flags = {
+ .val = 0,
+ .opts = trace_opts,
+};
+
+#define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
+
+/*
+ * Sequence count - we record it when starting a measurement and
+ * skip the latency if the sequence has changed - some other section
+ * did a maximum and could disturb our measurement with serial console
+ * printouts, etc. Truly coinciding maximum latencies should be rare
+ * and what happens together happens separately as well, so this doesn't
+ * decrease the validity of the maximum found:
+ */
+static __cacheline_aligned_in_smp unsigned long max_sequence;
+
+#ifdef CONFIG_FUNCTION_TRACER
+/*
+ * Prologue for the preempt and irqs off function tracers.
+ *
+ * Returns 1 if it is OK to continue, and data->disabled is
+ * incremented.
+ * 0 if the trace is to be ignored, and data->disabled
+ * is kept the same.
+ *
+ * Note, this function is also used outside this ifdef but
+ * inside the #ifdef of the function graph tracer below.
+ * This is OK, since the function graph tracer is
+ * dependent on the function tracer.
+ */
+static int func_prolog_dec(struct trace_array *tr,
+ struct trace_array_cpu **data,
+ unsigned long *flags)
+{
+ long disabled;
+ int cpu;
+
+ /*
+ * Does not matter if we preempt. We test the flags
+ * afterward, to see if irqs are disabled or not.
+ * If we preempt and get a false positive, the flags
+ * test will fail.
+ */
+ cpu = raw_smp_processor_id();
+ if (likely(!per_cpu(tracing_cpu, cpu)))
+ return 0;
+
+ local_save_flags(*flags);
+ /* slight chance to get a false positive on tracing_cpu */
+ if (!irqs_disabled_flags(*flags))
+ return 0;
+
+ *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
+ disabled = atomic_inc_return(&(*data)->disabled);
+
+ if (likely(disabled == 1))
+ return 1;
+
+ atomic_dec(&(*data)->disabled);
+
+ return 0;
+}
+
+/*
+ * irqsoff uses its own tracer function to keep the overhead down:
+ */
+static void
+irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *pt_regs)
+{
+ struct trace_array *tr = irqsoff_trace;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+
+ if (!func_prolog_dec(tr, &data, &flags))
+ return;
+
+ trace_function(tr, ip, parent_ip, flags, preempt_count());
+
+ atomic_dec(&data->disabled);
+}
+#endif /* CONFIG_FUNCTION_TRACER */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+static int
+irqsoff_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
+{
+ int cpu;
+
+ if (!(bit & TRACE_DISPLAY_GRAPH))
+ return -EINVAL;
+
+ if (!(is_graph() ^ set))
+ return 0;
+
+ stop_irqsoff_tracer(irqsoff_trace, !set);
+
+ for_each_possible_cpu(cpu)
+ per_cpu(tracing_cpu, cpu) = 0;
+
+ tr->max_latency = 0;
+ tracing_reset_online_cpus(&irqsoff_trace->trace_buffer);
+
+ return start_irqsoff_tracer(irqsoff_trace, set);
+}
+
+static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
+{
+ struct trace_array *tr = irqsoff_trace;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+ int ret;
+ int pc;
+
+ if (!func_prolog_dec(tr, &data, &flags))
+ return 0;
+
+ pc = preempt_count();
+ ret = __trace_graph_entry(tr, trace, flags, pc);
+ atomic_dec(&data->disabled);
+
+ return ret;
+}
+
+static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
+{
+ struct trace_array *tr = irqsoff_trace;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+ int pc;
+
+ if (!func_prolog_dec(tr, &data, &flags))
+ return;
+
+ pc = preempt_count();
+ __trace_graph_return(tr, trace, flags, pc);
+ atomic_dec(&data->disabled);
+}
+
+static void irqsoff_trace_open(struct trace_iterator *iter)
+{
+ if (is_graph())
+ graph_trace_open(iter);
+
+}
+
+static void irqsoff_trace_close(struct trace_iterator *iter)
+{
+ if (iter->private)
+ graph_trace_close(iter);
+}
+
+#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
+ TRACE_GRAPH_PRINT_PROC | \
+ TRACE_GRAPH_PRINT_ABS_TIME | \
+ TRACE_GRAPH_PRINT_DURATION)
+
+static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
+{
+ /*
+ * In graph mode call the graph tracer output function,
+ * otherwise go with the TRACE_FN event handler
+ */
+ if (is_graph())
+ return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
+
+ return TRACE_TYPE_UNHANDLED;
+}
+
+static void irqsoff_print_header(struct seq_file *s)
+{
+ if (is_graph())
+ print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
+ else
+ trace_default_header(s);
+}
+
+static void
+__trace_function(struct trace_array *tr,
+ unsigned long ip, unsigned long parent_ip,
+ unsigned long flags, int pc)
+{
+ if (is_graph())
+ trace_graph_function(tr, ip, parent_ip, flags, pc);
+ else
+ trace_function(tr, ip, parent_ip, flags, pc);
+}
+
+#else
+#define __trace_function trace_function
+
+static int
+irqsoff_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
+{
+ return -EINVAL;
+}
+
+static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
+{
+ return -1;
+}
+
+static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
+{
+ return TRACE_TYPE_UNHANDLED;
+}
+
+static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
+static void irqsoff_trace_open(struct trace_iterator *iter) { }
+static void irqsoff_trace_close(struct trace_iterator *iter) { }
+
+#ifdef CONFIG_FUNCTION_TRACER
+static void irqsoff_print_header(struct seq_file *s)
+{
+ trace_default_header(s);
+}
+#else
+static void irqsoff_print_header(struct seq_file *s)
+{
+ trace_latency_header(s);
+}
+#endif /* CONFIG_FUNCTION_TRACER */
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+/*
+ * Should this new latency be reported/recorded?
+ */
+static int report_latency(struct trace_array *tr, cycle_t delta)
+{
+ if (tracing_thresh) {
+ if (delta < tracing_thresh)
+ return 0;
+ } else {
+ if (delta <= tr->max_latency)
+ return 0;
+ }
+ return 1;
+}
+
+static void
+check_critical_timing(struct trace_array *tr,
+ struct trace_array_cpu *data,
+ unsigned long parent_ip,
+ int cpu)
+{
+ cycle_t T0, T1, delta;
+ unsigned long flags;
+ int pc;
+
+ T0 = data->preempt_timestamp;
+ T1 = ftrace_now(cpu);
+ delta = T1-T0;
+
+ local_save_flags(flags);
+
+ pc = preempt_count();
+
+ if (!report_latency(tr, delta))
+ goto out;
+
+ raw_spin_lock_irqsave(&max_trace_lock, flags);
+
+ /* check if we are still the max latency */
+ if (!report_latency(tr, delta))
+ goto out_unlock;
+
+ __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
+ /* Skip 5 functions to get to the irq/preempt enable function */
+ __trace_stack(tr, flags, 5, pc);
+
+ if (data->critical_sequence != max_sequence)
+ goto out_unlock;
+
+ data->critical_end = parent_ip;
+
+ if (likely(!is_tracing_stopped())) {
+ tr->max_latency = delta;
+ update_max_tr_single(tr, current, cpu);
+ }
+
+ max_sequence++;
+
+out_unlock:
+ raw_spin_unlock_irqrestore(&max_trace_lock, flags);
+
+out:
+ data->critical_sequence = max_sequence;
+ data->preempt_timestamp = ftrace_now(cpu);
+ __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
+}
+
+static inline void
+start_critical_timing(unsigned long ip, unsigned long parent_ip)
+{
+ int cpu;
+ struct trace_array *tr = irqsoff_trace;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+
+ if (!tracer_enabled || !tracing_is_enabled())
+ return;
+
+ cpu = raw_smp_processor_id();
+
+ if (per_cpu(tracing_cpu, cpu))
+ return;
+
+ data = per_cpu_ptr(tr->trace_buffer.data, cpu);
+
+ if (unlikely(!data) || atomic_read(&data->disabled))
+ return;
+
+ atomic_inc(&data->disabled);
+
+ data->critical_sequence = max_sequence;
+ data->preempt_timestamp = ftrace_now(cpu);
+ data->critical_start = parent_ip ? : ip;
+
+ local_save_flags(flags);
+
+ __trace_function(tr, ip, parent_ip, flags, preempt_count());
+
+ per_cpu(tracing_cpu, cpu) = 1;
+
+ atomic_dec(&data->disabled);
+}
+
+static inline void
+stop_critical_timing(unsigned long ip, unsigned long parent_ip)
+{
+ int cpu;
+ struct trace_array *tr = irqsoff_trace;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+
+ cpu = raw_smp_processor_id();
+ /* Always clear the tracing cpu on stopping the trace */
+ if (unlikely(per_cpu(tracing_cpu, cpu)))
+ per_cpu(tracing_cpu, cpu) = 0;
+ else
+ return;
+
+ if (!tracer_enabled || !tracing_is_enabled())
+ return;
+
+ data = per_cpu_ptr(tr->trace_buffer.data, cpu);
+
+ if (unlikely(!data) ||
+ !data->critical_start || atomic_read(&data->disabled))
+ return;
+
+ atomic_inc(&data->disabled);
+
+ local_save_flags(flags);
+ __trace_function(tr, ip, parent_ip, flags, preempt_count());
+ check_critical_timing(tr, data, parent_ip ? : ip, cpu);
+ data->critical_start = 0;
+ atomic_dec(&data->disabled);
+}
+
+/* start and stop critical timings used to for stoppage (in idle) */
+void start_critical_timings(void)
+{
+ if (preempt_trace() || irq_trace())
+ start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+EXPORT_SYMBOL_GPL(start_critical_timings);
+
+void stop_critical_timings(void)
+{
+ if (preempt_trace() || irq_trace())
+ stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+EXPORT_SYMBOL_GPL(stop_critical_timings);
+
+#ifdef CONFIG_IRQSOFF_TRACER
+#ifdef CONFIG_PROVE_LOCKING
+void time_hardirqs_on(unsigned long a0, unsigned long a1)
+{
+ if (!preempt_trace() && irq_trace())
+ stop_critical_timing(a0, a1);
+}
+
+void time_hardirqs_off(unsigned long a0, unsigned long a1)
+{
+ if (!preempt_trace() && irq_trace())
+ start_critical_timing(a0, a1);
+}
+
+#else /* !CONFIG_PROVE_LOCKING */
+
+/*
+ * Stubs:
+ */
+
+void trace_softirqs_on(unsigned long ip)
+{
+}
+
+void trace_softirqs_off(unsigned long ip)
+{
+}
+
+inline void print_irqtrace_events(struct task_struct *curr)
+{
+}
+
+/*
+ * We are only interested in hardirq on/off events:
+ */
+void trace_hardirqs_on(void)
+{
+ if (!preempt_trace() && irq_trace())
+ stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+EXPORT_SYMBOL(trace_hardirqs_on);
+
+void trace_hardirqs_off(void)
+{
+ if (!preempt_trace() && irq_trace())
+ start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+EXPORT_SYMBOL(trace_hardirqs_off);
+
+__visible void trace_hardirqs_on_caller(unsigned long caller_addr)
+{
+ if (!preempt_trace() && irq_trace())
+ stop_critical_timing(CALLER_ADDR0, caller_addr);
+}
+EXPORT_SYMBOL(trace_hardirqs_on_caller);
+
+__visible void trace_hardirqs_off_caller(unsigned long caller_addr)
+{
+ if (!preempt_trace() && irq_trace())
+ start_critical_timing(CALLER_ADDR0, caller_addr);
+}
+EXPORT_SYMBOL(trace_hardirqs_off_caller);
+
+#endif /* CONFIG_PROVE_LOCKING */
+#endif /* CONFIG_IRQSOFF_TRACER */
+
+#ifdef CONFIG_PREEMPT_TRACER
+void trace_preempt_on(unsigned long a0, unsigned long a1)
+{
+ if (preempt_trace() && !irq_trace())
+ stop_critical_timing(a0, a1);
+}
+
+void trace_preempt_off(unsigned long a0, unsigned long a1)
+{
+ if (preempt_trace() && !irq_trace())
+ start_critical_timing(a0, a1);
+}
+#endif /* CONFIG_PREEMPT_TRACER */
+
+static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
+{
+ int ret;
+
+ /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
+ if (function_enabled || (!set && !(trace_flags & TRACE_ITER_FUNCTION)))
+ return 0;
+
+ if (graph)
+ ret = register_ftrace_graph(&irqsoff_graph_return,
+ &irqsoff_graph_entry);
+ else
+ ret = register_ftrace_function(tr->ops);
+
+ if (!ret)
+ function_enabled = true;
+
+ return ret;
+}
+
+static void unregister_irqsoff_function(struct trace_array *tr, int graph)
+{
+ if (!function_enabled)
+ return;
+
+ if (graph)
+ unregister_ftrace_graph();
+ else
+ unregister_ftrace_function(tr->ops);
+
+ function_enabled = false;
+}
+
+static void irqsoff_function_set(struct trace_array *tr, int set)
+{
+ if (set)
+ register_irqsoff_function(tr, is_graph(), 1);
+ else
+ unregister_irqsoff_function(tr, is_graph());
+}
+
+static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
+{
+ struct tracer *tracer = tr->current_trace;
+
+ if (mask & TRACE_ITER_FUNCTION)
+ irqsoff_function_set(tr, set);
+
+ return trace_keep_overwrite(tracer, mask, set);
+}
+
+static int start_irqsoff_tracer(struct trace_array *tr, int graph)
+{
+ int ret;
+
+ ret = register_irqsoff_function(tr, graph, 0);
+
+ if (!ret && tracing_is_enabled())
+ tracer_enabled = 1;
+ else
+ tracer_enabled = 0;
+
+ return ret;
+}
+
+static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
+{
+ tracer_enabled = 0;
+
+ unregister_irqsoff_function(tr, graph);
+}
+
+static bool irqsoff_busy;
+
+static int __irqsoff_tracer_init(struct trace_array *tr)
+{
+ if (irqsoff_busy)
+ return -EBUSY;
+
+ save_flags = trace_flags;
+
+ /* non overwrite screws up the latency tracers */
+ set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
+ set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
+
+ tr->max_latency = 0;
+ irqsoff_trace = tr;
+ /* make sure that the tracer is visible */
+ smp_wmb();
+ tracing_reset_online_cpus(&tr->trace_buffer);
+
+ ftrace_init_array_ops(tr, irqsoff_tracer_call);
+
+ /* Only toplevel instance supports graph tracing */
+ if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
+ is_graph())))
+ printk(KERN_ERR "failed to start irqsoff tracer\n");
+
+ irqsoff_busy = true;
+ return 0;
+}
+
+static void irqsoff_tracer_reset(struct trace_array *tr)
+{
+ int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
+ int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
+
+ stop_irqsoff_tracer(tr, is_graph());
+
+ set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
+ set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
+ ftrace_reset_array_ops(tr);
+
+ irqsoff_busy = false;
+}
+
+static void irqsoff_tracer_start(struct trace_array *tr)
+{
+ tracer_enabled = 1;
+}
+
+static void irqsoff_tracer_stop(struct trace_array *tr)
+{
+ tracer_enabled = 0;
+}
+
+#ifdef CONFIG_IRQSOFF_TRACER
+static int irqsoff_tracer_init(struct trace_array *tr)
+{
+ trace_type = TRACER_IRQS_OFF;
+
+ return __irqsoff_tracer_init(tr);
+}
+static struct tracer irqsoff_tracer __read_mostly =
+{
+ .name = "irqsoff",
+ .init = irqsoff_tracer_init,
+ .reset = irqsoff_tracer_reset,
+ .start = irqsoff_tracer_start,
+ .stop = irqsoff_tracer_stop,
+ .print_max = true,
+ .print_header = irqsoff_print_header,
+ .print_line = irqsoff_print_line,
+ .flags = &tracer_flags,
+ .set_flag = irqsoff_set_flag,
+ .flag_changed = irqsoff_flag_changed,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_irqsoff,
+#endif
+ .open = irqsoff_trace_open,
+ .close = irqsoff_trace_close,
+ .allow_instances = true,
+ .use_max_tr = true,
+};
+# define register_irqsoff(trace) register_tracer(&trace)
+#else
+# define register_irqsoff(trace) do { } while (0)
+#endif
+
+#ifdef CONFIG_PREEMPT_TRACER
+static int preemptoff_tracer_init(struct trace_array *tr)
+{
+ trace_type = TRACER_PREEMPT_OFF;
+
+ return __irqsoff_tracer_init(tr);
+}
+
+static struct tracer preemptoff_tracer __read_mostly =
+{
+ .name = "preemptoff",
+ .init = preemptoff_tracer_init,
+ .reset = irqsoff_tracer_reset,
+ .start = irqsoff_tracer_start,
+ .stop = irqsoff_tracer_stop,
+ .print_max = true,
+ .print_header = irqsoff_print_header,
+ .print_line = irqsoff_print_line,
+ .flags = &tracer_flags,
+ .set_flag = irqsoff_set_flag,
+ .flag_changed = irqsoff_flag_changed,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_preemptoff,
+#endif
+ .open = irqsoff_trace_open,
+ .close = irqsoff_trace_close,
+ .allow_instances = true,
+ .use_max_tr = true,
+};
+# define register_preemptoff(trace) register_tracer(&trace)
+#else
+# define register_preemptoff(trace) do { } while (0)
+#endif
+
+#if defined(CONFIG_IRQSOFF_TRACER) && \
+ defined(CONFIG_PREEMPT_TRACER)
+
+static int preemptirqsoff_tracer_init(struct trace_array *tr)
+{
+ trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
+
+ return __irqsoff_tracer_init(tr);
+}
+
+static struct tracer preemptirqsoff_tracer __read_mostly =
+{
+ .name = "preemptirqsoff",
+ .init = preemptirqsoff_tracer_init,
+ .reset = irqsoff_tracer_reset,
+ .start = irqsoff_tracer_start,
+ .stop = irqsoff_tracer_stop,
+ .print_max = true,
+ .print_header = irqsoff_print_header,
+ .print_line = irqsoff_print_line,
+ .flags = &tracer_flags,
+ .set_flag = irqsoff_set_flag,
+ .flag_changed = irqsoff_flag_changed,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_preemptirqsoff,
+#endif
+ .open = irqsoff_trace_open,
+ .close = irqsoff_trace_close,
+ .allow_instances = true,
+ .use_max_tr = true,
+};
+
+# define register_preemptirqsoff(trace) register_tracer(&trace)
+#else
+# define register_preemptirqsoff(trace) do { } while (0)
+#endif
+
+__init static int init_irqsoff_tracer(void)
+{
+ register_irqsoff(irqsoff_tracer);
+ register_preemptoff(preemptoff_tracer);
+ register_preemptirqsoff(preemptirqsoff_tracer);
+
+ return 0;
+}
+core_initcall(init_irqsoff_tracer);