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authorSteven Rostedt <srostedt@redhat.com>2008-05-12 21:20:42 +0200
committerThomas Gleixner <tglx@linutronix.de>2008-05-23 20:32:46 +0200
commit81d68a96a39844853b37f20cc8282d9b65b78ef3 (patch)
treebbc05f415930c15fb5a1004620bd77585fcec43a
parent352ad25aa4a189c667cb2af333948d34692a2d27 (diff)
downloadlinux-81d68a96a39844853b37f20cc8282d9b65b78ef3.tar.bz2
ftrace: trace irq disabled critical timings
This patch adds latency tracing for critical timings (how long interrupts are disabled for). "irqsoff" is added to /debugfs/tracing/available_tracers Note: tracing_max_latency also holds the max latency for irqsoff (in usecs). (default to large number so one must start latency tracing) tracing_thresh threshold (in usecs) to always print out if irqs off is detected to be longer than stated here. If irq_thresh is non-zero, then max_irq_latency is ignored. Here's an example of a trace with ftrace_enabled = 0 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 Signed-off-by: Ingo Molnar <mingo@elte.hu> -------------------------------------------------------------------- latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1d.s3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1d.s3 100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1d.s3 100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= And this is a trace with ftrace_enabled == 1 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 -------------------------------------------------------------------- latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1dNs3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000]) swapper-0 1dNs3 46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000]) swapper-0 1dNs3 47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000]) swapper-0 1dNs3 47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47) swapper-0 1dNs3 97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50) swapper-0 1dNs3 98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000]) swapper-0 1dNs3 99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000]) swapper-0 1dNs3 101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--arch/x86/kernel/process_64.c3
-rw-r--r--arch/x86/lib/Makefile1
-rw-r--r--arch/x86/lib/thunk_32.S47
-rw-r--r--arch/x86/lib/thunk_64.S19
-rw-r--r--include/asm-x86/irqflags.h24
-rw-r--r--include/linux/ftrace.h8
-rw-r--r--include/linux/irqflags.h12
-rw-r--r--kernel/fork.c2
-rw-r--r--kernel/lockdep.c23
-rw-r--r--kernel/printk.c2
-rw-r--r--kernel/trace/Kconfig18
-rw-r--r--kernel/trace/Makefile1
-rw-r--r--kernel/trace/trace_irqsoff.c402
13 files changed, 531 insertions, 31 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index e2319f39988b..dd349c92f051 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -165,7 +165,10 @@ void cpu_idle(void)
*/
local_irq_disable();
enter_idle();
+ /* Don't trace irqs off for idle */
+ stop_critical_timings();
idle();
+ start_critical_timings();
/* In many cases the interrupt that ended idle
has already called exit_idle. But some idle
loops can be woken up without interrupt. */
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 76f60f52a885..84aa2883fe15 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -5,6 +5,7 @@
obj-$(CONFIG_SMP) := msr-on-cpu.o
lib-y := delay_$(BITS).o
+lib-y += thunk_$(BITS).o
lib-y += usercopy_$(BITS).o getuser_$(BITS).o putuser_$(BITS).o
lib-y += memcpy_$(BITS).o
diff --git a/arch/x86/lib/thunk_32.S b/arch/x86/lib/thunk_32.S
new file mode 100644
index 000000000000..650b11e00ecc
--- /dev/null
+++ b/arch/x86/lib/thunk_32.S
@@ -0,0 +1,47 @@
+/*
+ * Trampoline to trace irqs off. (otherwise CALLER_ADDR1 might crash)
+ * Copyright 2008 by Steven Rostedt, Red Hat, Inc
+ * (inspired by Andi Kleen's thunk_64.S)
+ * Subject to the GNU public license, v.2. No warranty of any kind.
+ */
+
+ #include <linux/linkage.h>
+
+#define ARCH_TRACE_IRQS_ON \
+ pushl %eax; \
+ pushl %ecx; \
+ pushl %edx; \
+ call trace_hardirqs_on; \
+ popl %edx; \
+ popl %ecx; \
+ popl %eax;
+
+#define ARCH_TRACE_IRQS_OFF \
+ pushl %eax; \
+ pushl %ecx; \
+ pushl %edx; \
+ call trace_hardirqs_off; \
+ popl %edx; \
+ popl %ecx; \
+ popl %eax;
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+ /* put return address in eax (arg1) */
+ .macro thunk_ra name,func
+ .globl \name
+\name:
+ pushl %eax
+ pushl %ecx
+ pushl %edx
+ /* Place EIP in the arg1 */
+ movl 3*4(%esp), %eax
+ call \func
+ popl %edx
+ popl %ecx
+ popl %eax
+ ret
+ .endm
+
+ thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
+ thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
+#endif
diff --git a/arch/x86/lib/thunk_64.S b/arch/x86/lib/thunk_64.S
index e009251d4e9f..bf9a7d5a5428 100644
--- a/arch/x86/lib/thunk_64.S
+++ b/arch/x86/lib/thunk_64.S
@@ -2,6 +2,7 @@
* Save registers before calling assembly functions. This avoids
* disturbance of register allocation in some inline assembly constructs.
* Copyright 2001,2002 by Andi Kleen, SuSE Labs.
+ * Added trace_hardirqs callers - Copyright 2007 Steven Rostedt, Red Hat, Inc.
* Subject to the GNU public license, v.2. No warranty of any kind.
*/
@@ -42,8 +43,22 @@
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
- thunk trace_hardirqs_on_thunk,trace_hardirqs_on
- thunk trace_hardirqs_off_thunk,trace_hardirqs_off
+ /* put return address in rdi (arg1) */
+ .macro thunk_ra name,func
+ .globl \name
+\name:
+ CFI_STARTPROC
+ SAVE_ARGS
+ /* SAVE_ARGS pushs 9 elements */
+ /* the next element would be the rip */
+ movq 9*8(%rsp), %rdi
+ call \func
+ jmp restore
+ CFI_ENDPROC
+ .endm
+
+ thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
+ thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOC
diff --git a/include/asm-x86/irqflags.h b/include/asm-x86/irqflags.h
index c242527f970e..24d71b1eb189 100644
--- a/include/asm-x86/irqflags.h
+++ b/include/asm-x86/irqflags.h
@@ -179,8 +179,6 @@ static inline void trace_hardirqs_fixup(void)
* have a reliable stack. x86_64 only.
*/
#define SWAPGS_UNSAFE_STACK swapgs
-#define ARCH_TRACE_IRQS_ON call trace_hardirqs_on_thunk
-#define ARCH_TRACE_IRQS_OFF call trace_hardirqs_off_thunk
#define ARCH_LOCKDEP_SYS_EXIT call lockdep_sys_exit_thunk
#define ARCH_LOCKDEP_SYS_EXIT_IRQ \
TRACE_IRQS_ON; \
@@ -192,24 +190,6 @@ static inline void trace_hardirqs_fixup(void)
TRACE_IRQS_OFF;
#else
-#define ARCH_TRACE_IRQS_ON \
- pushl %eax; \
- pushl %ecx; \
- pushl %edx; \
- call trace_hardirqs_on; \
- popl %edx; \
- popl %ecx; \
- popl %eax;
-
-#define ARCH_TRACE_IRQS_OFF \
- pushl %eax; \
- pushl %ecx; \
- pushl %edx; \
- call trace_hardirqs_off; \
- popl %edx; \
- popl %ecx; \
- popl %eax;
-
#define ARCH_LOCKDEP_SYS_EXIT \
pushl %eax; \
pushl %ecx; \
@@ -223,8 +203,8 @@ static inline void trace_hardirqs_fixup(void)
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
-# define TRACE_IRQS_ON ARCH_TRACE_IRQS_ON
-# define TRACE_IRQS_OFF ARCH_TRACE_IRQS_OFF
+# define TRACE_IRQS_ON call trace_hardirqs_on_thunk;
+# define TRACE_IRQS_OFF call trace_hardirqs_off_thunk;
#else
# define TRACE_IRQS_ON
# define TRACE_IRQS_OFF
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index db8a5e7abe41..0a20445dcbcc 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -50,4 +50,12 @@ extern void mcount(void);
# define CALLER_ADDR5 0UL
#endif
+#ifdef CONFIG_IRQSOFF_TRACER
+ extern void notrace time_hardirqs_on(unsigned long a0, unsigned long a1);
+ extern void notrace time_hardirqs_off(unsigned long a0, unsigned long a1);
+#else
+# define time_hardirqs_on(a0, a1) do { } while (0)
+# define time_hardirqs_off(a0, a1) do { } while (0)
+#endif
+
#endif /* _LINUX_FTRACE_H */
diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
index e600c4e9b8c5..5b711d4e9fd9 100644
--- a/include/linux/irqflags.h
+++ b/include/linux/irqflags.h
@@ -12,10 +12,10 @@
#define _LINUX_TRACE_IRQFLAGS_H
#ifdef CONFIG_TRACE_IRQFLAGS
- extern void trace_hardirqs_on(void);
- extern void trace_hardirqs_off(void);
extern void trace_softirqs_on(unsigned long ip);
extern void trace_softirqs_off(unsigned long ip);
+ extern void trace_hardirqs_on(void);
+ extern void trace_hardirqs_off(void);
# define trace_hardirq_context(p) ((p)->hardirq_context)
# define trace_softirq_context(p) ((p)->softirq_context)
# define trace_hardirqs_enabled(p) ((p)->hardirqs_enabled)
@@ -41,6 +41,14 @@
# define INIT_TRACE_IRQFLAGS
#endif
+#ifdef CONFIG_IRQSOFF_TRACER
+ extern void stop_critical_timings(void);
+ extern void start_critical_timings(void);
+#else
+# define stop_critical_timings() do { } while (0)
+# define start_critical_timings() do { } while (0)
+#endif
+
#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
#include <asm/irqflags.h>
diff --git a/kernel/fork.c b/kernel/fork.c
index 19908b26cf80..d66d676dc362 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -909,7 +909,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
rt_mutex_init_task(p);
-#ifdef CONFIG_TRACE_IRQFLAGS
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_LOCKDEP)
DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
#endif
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 81a4e4a3f087..e21924365ea3 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -39,6 +39,7 @@
#include <linux/irqflags.h>
#include <linux/utsname.h>
#include <linux/hash.h>
+#include <linux/ftrace.h>
#include <asm/sections.h>
@@ -982,7 +983,7 @@ check_noncircular(struct lock_class *source, unsigned int depth)
return 1;
}
-#ifdef CONFIG_TRACE_IRQFLAGS
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
/*
* Forwards and backwards subgraph searching, for the purposes of
* proving that two subgraphs can be connected by a new dependency
@@ -1680,7 +1681,7 @@ valid_state(struct task_struct *curr, struct held_lock *this,
static int mark_lock(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit);
-#ifdef CONFIG_TRACE_IRQFLAGS
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
/*
* print irq inversion bug:
@@ -2013,11 +2014,13 @@ void early_boot_irqs_on(void)
/*
* Hardirqs will be enabled:
*/
-void trace_hardirqs_on(void)
+void notrace trace_hardirqs_on_caller(unsigned long a0)
{
struct task_struct *curr = current;
unsigned long ip;
+ time_hardirqs_on(CALLER_ADDR0, a0);
+
if (unlikely(!debug_locks || current->lockdep_recursion))
return;
@@ -2055,16 +2058,23 @@ void trace_hardirqs_on(void)
curr->hardirq_enable_event = ++curr->irq_events;
debug_atomic_inc(&hardirqs_on_events);
}
+EXPORT_SYMBOL(trace_hardirqs_on_caller);
+void notrace trace_hardirqs_on(void)
+{
+ trace_hardirqs_on_caller(CALLER_ADDR0);
+}
EXPORT_SYMBOL(trace_hardirqs_on);
/*
* Hardirqs were disabled:
*/
-void trace_hardirqs_off(void)
+void notrace trace_hardirqs_off_caller(unsigned long a0)
{
struct task_struct *curr = current;
+ time_hardirqs_off(CALLER_ADDR0, a0);
+
if (unlikely(!debug_locks || current->lockdep_recursion))
return;
@@ -2082,7 +2092,12 @@ void trace_hardirqs_off(void)
} else
debug_atomic_inc(&redundant_hardirqs_off);
}
+EXPORT_SYMBOL(trace_hardirqs_off_caller);
+void notrace trace_hardirqs_off(void)
+{
+ trace_hardirqs_off_caller(CALLER_ADDR0);
+}
EXPORT_SYMBOL(trace_hardirqs_off);
/*
diff --git a/kernel/printk.c b/kernel/printk.c
index 8fb01c32aa3b..ae7d5b9e535d 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1041,7 +1041,9 @@ void release_console_sem(void)
_log_end = log_end;
con_start = log_end; /* Flush */
spin_unlock(&logbuf_lock);
+ stop_critical_timings(); /* don't trace print latency */
call_console_drivers(_con_start, _log_end);
+ start_critical_timings();
local_irq_restore(flags);
}
console_locked = 0;
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 892ecc94a82b..896df1cf6adc 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -26,6 +26,24 @@ config FTRACE
(the bootup default), then the overhead of the instructions is very
small and not measurable even in micro-benchmarks.
+config IRQSOFF_TRACER
+ bool "Interrupts-off Latency Tracer"
+ default n
+ depends on TRACE_IRQFLAGS_SUPPORT
+ depends on GENERIC_TIME
+ select TRACE_IRQFLAGS
+ select TRACING
+ select TRACER_MAX_TRACE
+ help
+ This option measures the time spent in irqs-off critical
+ sections, with microsecond accuracy.
+
+ The default measurement method is a maximum search, which is
+ disabled by default and can be runtime (re-)started
+ via:
+
+ echo 0 > /debugfs/tracing/tracing_max_latency
+
config SCHED_TRACER
bool "Scheduling Latency Tracer"
depends on DEBUG_KERNEL
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 5508cdb19aea..46be8647fb65 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_FTRACE) += libftrace.o
obj-$(CONFIG_TRACING) += trace.o
obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
obj-$(CONFIG_FTRACE) += trace_functions.o
+obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
libftrace-y := ftrace.o
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);