summaryrefslogtreecommitdiffstats
path: root/kernel/trace/trace_irqsoff.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/trace/trace_irqsoff.c')
-rw-r--r--kernel/trace/trace_irqsoff.c486
1 files changed, 486 insertions, 0 deletions
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
new file mode 100644
index 00000000000..421d6fe3650
--- /dev/null
+++ b/kernel/trace/trace_irqsoff.c
@@ -0,0 +1,486 @@
+/*
+ * 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;
+
+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;
+
+#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
+
+/*
+ * 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
+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;
+
+ /*
+ * 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;
+
+ local_save_flags(flags);
+ /* slight chance to get a false positive on tracing_cpu */
+ if (!irqs_disabled_flags(flags))
+ return;
+
+ data = tr->data[cpu];
+ disabled = atomic_inc_return(&data->disabled);
+
+ if (likely(disabled == 1))
+ trace_function(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 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)
+{
+ unsigned long latency, t0, t1;
+ cycle_t T0, T1, delta;
+ unsigned long flags;
+
+ /*
+ * usecs conversion is slow so we try to delay the conversion
+ * as long as possible:
+ */
+ T0 = data->preempt_timestamp;
+ T1 = ftrace_now(cpu);
+ delta = T1-T0;
+
+ local_save_flags(flags);
+
+ 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, data, CALLER_ADDR0, parent_ip, flags);
+
+ latency = nsecs_to_usecs(delta);
+
+ if (data->critical_sequence != max_sequence)
+ goto out_unlock;
+
+ 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);
+
+ max_sequence++;
+
+out_unlock:
+ spin_unlock_irqrestore(&max_trace_lock, flags);
+
+out:
+ data->critical_sequence = max_sequence;
+ data->preempt_timestamp = ftrace_now(cpu);
+ tracing_reset(data);
+ trace_function(tr, data, CALLER_ADDR0, parent_ip, flags);
+}
+
+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;
+ tracing_reset(data);
+
+ local_save_flags(flags);
+
+ trace_function(tr, data, ip, parent_ip, flags);
+
+ 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) || unlikely(!head_page(data)) ||
+ !data->critical_start || atomic_read(&data->disabled))
+ return;
+
+ atomic_inc(&data->disabled);
+
+ local_save_flags(flags);
+ trace_function(tr, data, ip, parent_ip, flags);
+ 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);
+}
+
+void stop_critical_timings(void)
+{
+ if (preempt_trace() || irq_trace())
+ stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+
+#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 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 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)
+{
+ stop_critical_timing(a0, a1);
+}
+
+void trace_preempt_off(unsigned long a0, unsigned long a1)
+{
+ start_critical_timing(a0, a1);
+}
+#endif /* CONFIG_PREEMPT_TRACER */
+
+static void start_irqsoff_tracer(struct trace_array *tr)
+{
+ register_ftrace_function(&trace_ops);
+ tracer_enabled = 1;
+}
+
+static void stop_irqsoff_tracer(struct trace_array *tr)
+{
+ tracer_enabled = 0;
+ unregister_ftrace_function(&trace_ops);
+}
+
+static void __irqsoff_tracer_init(struct trace_array *tr)
+{
+ irqsoff_trace = tr;
+ /* make sure that the tracer is visible */
+ 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 irqsoff_tracer_open(struct trace_iterator *iter)
+{
+ /* stop the trace while dumping */
+ if (iter->tr->ctrl)
+ stop_irqsoff_tracer(iter->tr);
+}
+
+static void irqsoff_tracer_close(struct trace_iterator *iter)
+{
+ if (iter->tr->ctrl)
+ start_irqsoff_tracer(iter->tr);
+}
+
+#ifdef CONFIG_IRQSOFF_TRACER
+static void irqsoff_tracer_init(struct trace_array *tr)
+{
+ trace_type = TRACER_IRQS_OFF;
+
+ __irqsoff_tracer_init(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,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_irqsoff,
+#endif
+};
+# define register_irqsoff(trace) register_tracer(&trace)
+#else
+# define register_irqsoff(trace) do { } while (0)
+#endif
+
+#ifdef CONFIG_PREEMPT_TRACER
+static void preemptoff_tracer_init(struct trace_array *tr)
+{
+ trace_type = TRACER_PREEMPT_OFF;
+
+ __irqsoff_tracer_init(tr);
+}
+
+static struct tracer preemptoff_tracer __read_mostly =
+{
+ .name = "preemptoff",
+ .init = preemptoff_tracer_init,
+ .reset = irqsoff_tracer_reset,
+ .open = irqsoff_tracer_open,
+ .close = irqsoff_tracer_close,
+ .ctrl_update = irqsoff_tracer_ctrl_update,
+ .print_max = 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_preemptoff,
+#endif
+};
+# 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 void preemptirqsoff_tracer_init(struct trace_array *tr)
+{
+ trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
+
+ __irqsoff_tracer_init(tr);
+}
+
+static struct tracer preemptirqsoff_tracer __read_mostly =
+{
+ .name = "preemptirqsoff",
+ .init = preemptirqsoff_tracer_init,
+ .reset = irqsoff_tracer_reset,
+ .open = irqsoff_tracer_open,
+ .close = irqsoff_tracer_close,
+ .ctrl_update = irqsoff_tracer_ctrl_update,
+ .print_max = 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_preemptirqsoff,
+#endif
+};
+
+# 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);