linux/kernel/trace/trace_irqsoff.c
Tejun Heo 2ce802f62b lockdep: Move early boot local IRQ enable/disable status to init/main.c
During early boot, local IRQ is disabled until IRQ subsystem is
properly initialized.  During this time, no one should enable
local IRQ and some operations which usually are not allowed with
IRQ disabled, e.g. operations which might sleep or require
communications with other processors, are allowed.

lockdep tracked this with early_boot_irqs_off/on() callbacks.
As other subsystems need this information too, move it to
init/main.c and make it generally available.  While at it,
toggle the boolean to early_boot_irqs_disabled instead of
enabled so that it can be initialized with %false and %true
indicates the exceptional condition.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110120110635.GB6036@htj.dyndns.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-01-20 13:32:33 +01:00

687 lines
15 KiB
C

/*
* 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 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;
static DEFINE_PER_CPU(int, tracing_cpu);
static DEFINE_SPINLOCK(max_trace_lock);
enum {
TRACER_IRQS_OFF = (1 << 1),
TRACER_PREEMPT_OFF = (1 << 2),
};
static int trace_type __read_mostly;
static int save_lat_flag;
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 doesnt
* 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 = tr->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 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);
}
static struct ftrace_ops trace_ops __read_mostly =
{
.func = irqsoff_tracer_call,
};
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static int irqsoff_set_flag(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;
tracing_max_latency = 0;
tracing_reset_online_cpus(irqsoff_trace);
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)
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(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_print_header(struct seq_file *s) { }
static void irqsoff_trace_open(struct trace_iterator *iter) { }
static void irqsoff_trace_close(struct trace_iterator *iter) { }
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
/*
* Should this new latency be reported/recorded?
*/
static int 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
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(delta))
goto out;
spin_lock_irqsave(&max_trace_lock, flags);
/* check if we are still the max latency */
if (!report_latency(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())) {
tracing_max_latency = delta;
update_max_tr_single(tr, current, cpu);
}
max_sequence++;
out_unlock:
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 (likely(!tracer_enabled))
return;
cpu = raw_smp_processor_id();
if (per_cpu(tracing_cpu, cpu))
return;
data = tr->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)
return;
data = tr->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);
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);
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())
stop_critical_timing(a0, a1);
}
void trace_preempt_off(unsigned long a0, unsigned long a1)
{
if (preempt_trace())
start_critical_timing(a0, a1);
}
#endif /* CONFIG_PREEMPT_TRACER */
static int start_irqsoff_tracer(struct trace_array *tr, int graph)
{
int ret = 0;
if (!graph)
ret = register_ftrace_function(&trace_ops);
else
ret = register_ftrace_graph(&irqsoff_graph_return,
&irqsoff_graph_entry);
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;
if (!graph)
unregister_ftrace_function(&trace_ops);
else
unregister_ftrace_graph();
}
static void __irqsoff_tracer_init(struct trace_array *tr)
{
save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
trace_flags |= TRACE_ITER_LATENCY_FMT;
tracing_max_latency = 0;
irqsoff_trace = tr;
/* make sure that the tracer is visible */
smp_wmb();
tracing_reset_online_cpus(tr);
if (start_irqsoff_tracer(tr, is_graph()))
printk(KERN_ERR "failed to start irqsoff tracer\n");
}
static void irqsoff_tracer_reset(struct trace_array *tr)
{
stop_irqsoff_tracer(tr, is_graph());
if (!save_lat_flag)
trace_flags &= ~TRACE_ITER_LATENCY_FMT;
}
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;
__irqsoff_tracer_init(tr);
return 0;
}
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 = 1,
.print_header = irqsoff_print_header,
.print_line = irqsoff_print_line,
.flags = &tracer_flags,
.set_flag = irqsoff_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_irqsoff,
#endif
.open = irqsoff_trace_open,
.close = irqsoff_trace_close,
.use_max_tr = 1,
};
# 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;
__irqsoff_tracer_init(tr);
return 0;
}
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 = 1,
.print_header = irqsoff_print_header,
.print_line = irqsoff_print_line,
.flags = &tracer_flags,
.set_flag = irqsoff_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_preemptoff,
#endif
.open = irqsoff_trace_open,
.close = irqsoff_trace_close,
.use_max_tr = 1,
};
# 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;
__irqsoff_tracer_init(tr);
return 0;
}
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 = 1,
.print_header = irqsoff_print_header,
.print_line = irqsoff_print_line,
.flags = &tracer_flags,
.set_flag = irqsoff_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_preemptirqsoff,
#endif
.open = irqsoff_trace_open,
.close = irqsoff_trace_close,
.use_max_tr = 1,
};
# 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;
}
device_initcall(init_irqsoff_tracer);