/*

   * 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 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

  #ifdef CONFIG_FUNCTION_GRAPH_TRACER

  static int irqsoff_display_graph(struct trace_array *tr, int set);

  # define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)

  #else
  static inline int irqsoff_display_graph(struct trace_array *tr, int set)
  {
  	return -EINVAL;
  }

  # define is_graph(tr) false

  #endif

  /*
   * 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,
  	 * although I'm starting to think there isn't a chance.
  	 * Leave this for now just to be paranoid.
  	 */
  	if (!irqs_disabled_flags(*flags) && !preempt_count())

  		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_display_graph(struct trace_array *tr, int set)

  {
  	int cpu;

  	if (!(is_graph(tr) ^ 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(iter->tr))

  		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(iter->tr))

  		return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);

  
  	return TRACE_TYPE_UNHANDLED;
  }
  
  static void irqsoff_print_header(struct seq_file *s)
  {

  	struct trace_array *tr = irqsoff_trace;
  
  	if (is_graph(tr))

  		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(tr))

  		trace_graph_function(tr, ip, parent_ip, flags, pc);
  	else

  		trace_function(tr, ip, parent_ip, flags, pc);

  }
  
  #else
  #define __trace_function trace_function

  #ifdef CONFIG_FUNCTION_TRACER

  static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
  {
  	return -1;
  }

  #endif

  
  static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
  {
  	return TRACE_TYPE_UNHANDLED;
  }

  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_graph_return(struct ftrace_graph_ret *trace) { }

  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 bool report_latency(struct trace_array *tr, cycle_t delta)

  {
  	if (tracing_thresh) {
  		if (delta < tracing_thresh)

  			return false;

  	} else {

  		if (delta <= tr->max_latency)

  			return false;

  	}

  	return true;

  }

  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 */

  #ifdef CONFIG_FUNCTION_TRACER
  static bool function_enabled;

  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 && !(tr->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 int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)

  {

  	if (!(mask & TRACE_ITER_FUNCTION))
  		return 0;

  	if (set)

  		register_irqsoff_function(tr, is_graph(tr), 1);

  	else

  		unregister_irqsoff_function(tr, is_graph(tr));

  	return 1;
  }
  #else
  static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
  {

  	return 0;

  }

  static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
  static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
  {
  	return 0;
  }
  #endif /* CONFIG_FUNCTION_TRACER */

  static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)

  {

  	struct tracer *tracer = tr->current_trace;

  	if (irqsoff_function_set(tr, mask, set))
  		return 0;

  #ifdef CONFIG_FUNCTION_GRAPH_TRACER

  	if (mask & TRACE_ITER_DISPLAY_GRAPH)
  		return irqsoff_display_graph(tr, set);

  #endif

  
  	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 = tr->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();

  	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(tr))))

  		printk(KERN_ERR "failed to start irqsoff tracer
  ");

  
  	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(tr));

  	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,

  	.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,

  	.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,

  	.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);