1 files changed, 402 insertions, 0 deletions
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
new file mode 100644
index 000000000000..a9131b0cf1a5
--- /dev/null
+++ b/kernel/trace/trace_irqsoff.c
@@ -0,0 +1,402 @@
+/*
+ * trace irqs off criticall 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 William Lee Irwin III
+ */
+#include <linux/kallsyms.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/ftrace.h>
+#include <linux/fs.h>
+
+#include "trace.h"
+
+static struct trace_array		*irqsoff_trace __read_mostly;
+static int				tracer_enabled __read_mostly;
+
+/*
+ * 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 doesnt
+ * decrease the validity of the maximum found:
+ */
+static __cacheline_aligned_in_smp	unsigned long max_sequence;
+
+#ifdef CONFIG_FTRACE
+/*
+ * irqsoff uses its own tracer function to keep the overhead down:
+ */
+static void notrace
+irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
+{
+	struct trace_array *tr = irqsoff_trace;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+
+	if (likely(!tracer_enabled))
+		return;
+
+	local_save_flags(flags);
+
+	if (!irqs_disabled_flags(flags))
+		return;
+
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+	disabled = atomic_inc_return(&data->disabled);
+
+	if (likely(disabled == 1))
+		ftrace(tr, data, ip, parent_ip, flags);
+
+	atomic_dec(&data->disabled);
+}
+
+static struct ftrace_ops trace_ops __read_mostly =
+{
+	.func = irqsoff_tracer_call,
+};
+#endif /* CONFIG_FTRACE */
+
+/*
+ * Should this new latency be reported/recorded?
+ */
+static int notrace report_latency(cycle_t delta)
+{
+	if (tracing_thresh) {
+		if (delta < tracing_thresh)
+			return 0;
+	} else {
+		if (delta <= tracing_max_latency)
+			return 0;
+	}
+	return 1;
+}
+
+static void notrace
+check_critical_timing(struct trace_array *tr,
+		      struct trace_array_cpu *data,
+		      unsigned long parent_ip,
+		      int cpu)
+{
+	unsigned long latency, t0, t1;
+	cycle_t T0, T1, T2, delta;
+	unsigned long flags;
+
+	/*
+	 * usecs conversion is slow so we try to delay the conversion
+	 * as long as possible:
+	 */
+	T0 = data->preempt_timestamp;
+	T1 = now(cpu);
+	delta = T1-T0;
+
+	local_save_flags(flags);
+
+	if (!report_latency(delta))
+		goto out;
+
+	ftrace(tr, data, CALLER_ADDR0, parent_ip, flags);
+	/*
+	 * Update the timestamp, because the trace entry above
+	 * might change it (it can only get larger so the latency
+	 * is fair to be reported):
+	 */
+	T2 = now(cpu);
+
+	delta = T2-T0;
+
+	latency = nsecs_to_usecs(delta);
+
+	if (data->critical_sequence != max_sequence)
+		goto out;
+
+	tracing_max_latency = delta;
+	t0 = nsecs_to_usecs(T0);
+	t1 = nsecs_to_usecs(T1);
+
+	data->critical_end = parent_ip;
+
+	update_max_tr_single(tr, current, cpu);
+
+	if (tracing_thresh)
+		printk(KERN_INFO "(%16s-%-5d|#%d): %lu us critical section "
+		       "violates %lu us threshold.\n"
+		       " => started at timestamp %lu: ",
+				current->comm, current->pid,
+				raw_smp_processor_id(),
+				latency, nsecs_to_usecs(tracing_thresh), t0);
+	else
+		printk(KERN_INFO "(%16s-%-5d|#%d):"
+		       " new %lu us maximum-latency "
+		       "critical section.\n => started at timestamp %lu: ",
+				current->comm, current->pid,
+				raw_smp_processor_id(),
+				latency, t0);
+
+	print_symbol(KERN_CONT "<%s>\n", data->critical_start);
+	printk(KERN_CONT " =>   ended at timestamp %lu: ", t1);
+	print_symbol(KERN_CONT "<%s>\n", data->critical_end);
+	dump_stack();
+	t1 = nsecs_to_usecs(now(cpu));
+	printk(KERN_CONT " =>   dump-end timestamp %lu\n\n", t1);
+
+	max_sequence++;
+
+out:
+	data->critical_sequence = max_sequence;
+	data->preempt_timestamp = now(cpu);
+	tracing_reset(data);
+	ftrace(tr, data, CALLER_ADDR0, parent_ip, flags);
+}
+
+static inline void notrace
+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 (likely(!tracer_enabled))
+		return;
+
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+
+	if (unlikely(!data) || unlikely(!data->trace) ||
+	    data->critical_start || atomic_read(&data->disabled))
+		return;
+
+	atomic_inc(&data->disabled);
+
+	data->critical_sequence = max_sequence;
+	data->preempt_timestamp = now(cpu);
+	data->critical_start = parent_ip;
+	tracing_reset(data);
+
+	local_save_flags(flags);
+	ftrace(tr, data, ip, parent_ip, flags);
+
+	atomic_dec(&data->disabled);
+}
+
+static inline void notrace
+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;
+
+	if (likely(!tracer_enabled))
+		return;
+
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+
+	if (unlikely(!data) || unlikely(!data->trace) ||
+	    !data->critical_start || atomic_read(&data->disabled))
+		return;
+
+	atomic_inc(&data->disabled);
+	local_save_flags(flags);
+	ftrace(tr, data, ip, parent_ip, flags);
+	check_critical_timing(tr, data, parent_ip, cpu);
+	data->critical_start = 0;
+	atomic_dec(&data->disabled);
+}
+
+void notrace start_critical_timings(void)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+
+	if (irqs_disabled_flags(flags))
+		start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+
+void notrace stop_critical_timings(void)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+
+	if (irqs_disabled_flags(flags))
+		stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+
+#ifdef CONFIG_PROVE_LOCKING
+void notrace time_hardirqs_on(unsigned long a0, unsigned long a1)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+
+	if (irqs_disabled_flags(flags))
+		stop_critical_timing(a0, a1);
+}
+
+void notrace time_hardirqs_off(unsigned long a0, unsigned long a1)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+
+	if (irqs_disabled_flags(flags))
+		start_critical_timing(a0, a1);
+}
+
+#else /* !CONFIG_PROVE_LOCKING */
+
+/*
+ * Stubs:
+ */
+
+void early_boot_irqs_off(void)
+{
+}
+
+void early_boot_irqs_on(void)
+{
+}
+
+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 notrace trace_hardirqs_on(void)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+
+	if (irqs_disabled_flags(flags))
+		stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+EXPORT_SYMBOL(trace_hardirqs_on);
+
+void notrace trace_hardirqs_off(void)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+
+	if (irqs_disabled_flags(flags))
+		start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+EXPORT_SYMBOL(trace_hardirqs_off);
+
+void notrace trace_hardirqs_on_caller(unsigned long caller_addr)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+
+	if (irqs_disabled_flags(flags))
+		stop_critical_timing(CALLER_ADDR0, caller_addr);
+}
+EXPORT_SYMBOL(trace_hardirqs_on_caller);
+
+void notrace trace_hardirqs_off_caller(unsigned long caller_addr)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+
+	if (irqs_disabled_flags(flags))
+		start_critical_timing(CALLER_ADDR0, caller_addr);
+}
+EXPORT_SYMBOL(trace_hardirqs_off_caller);
+
+#endif /* CONFIG_PROVE_LOCKING */
+
+static void start_irqsoff_tracer(struct trace_array *tr)
+{
+	tracer_enabled = 1;
+	register_ftrace_function(&trace_ops);
+}
+
+static void stop_irqsoff_tracer(struct trace_array *tr)
+{
+	unregister_ftrace_function(&trace_ops);
+	tracer_enabled = 0;
+}
+
+static void irqsoff_tracer_init(struct trace_array *tr)
+{
+	irqsoff_trace = tr;
+	/* make sure that the tracer is visibel */
+	smp_wmb();
+
+	if (tr->ctrl)
+		start_irqsoff_tracer(tr);
+}
+
+static void irqsoff_tracer_reset(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		stop_irqsoff_tracer(tr);
+}
+
+static void irqsoff_tracer_ctrl_update(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		start_irqsoff_tracer(tr);
+	else
+		stop_irqsoff_tracer(tr);
+}
+
+static void notrace irqsoff_tracer_open(struct trace_iterator *iter)
+{
+	/* stop the trace while dumping */
+	if (iter->tr->ctrl)
+		stop_irqsoff_tracer(iter->tr);
+}
+
+static void notrace irqsoff_tracer_close(struct trace_iterator *iter)
+{
+	if (iter->tr->ctrl)
+		start_irqsoff_tracer(iter->tr);
+}
+
+static struct tracer irqsoff_tracer __read_mostly =
+{
+	.name		= "irqsoff",
+	.init		= irqsoff_tracer_init,
+	.reset		= irqsoff_tracer_reset,
+	.open		= irqsoff_tracer_open,
+	.close		= irqsoff_tracer_close,
+	.ctrl_update	= irqsoff_tracer_ctrl_update,
+	.print_max	= 1,
+};
+
+__init static int init_irqsoff_tracer(void)
+{
+	register_tracer(&irqsoff_tracer);
+
+	return 0;
+}
+device_initcall(init_irqsoff_tracer);