[15/19] ftrace: trace irq disabled critical timings

From: Ingo Molnar
Date: Sun Feb 10 2008 - 02:26:52 EST

From: Steven Rostedt <srostedt@xxxxxxxxxx>

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
--------------------------------------------------------------------
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@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/x86/kernel/process_64.c | 3
arch/x86/lib/Makefile | 1
arch/x86/lib/thunk_32.S | 47 +++++
arch/x86/lib/thunk_64.S | 19 +-
include/asm-x86/irqflags.h | 24 --
include/linux/ftrace.h | 8
include/linux/irqflags.h | 12 +
kernel/fork.c | 2
kernel/lockdep.c | 23 ++
kernel/printk.c | 2
kernel/trace/Kconfig | 18 +
kernel/trace/Makefile | 1
kernel/trace/trace_irqsoff.c | 402 +++++++++++++++++++++++++++++++++++++++++++
13 files changed, 531 insertions(+), 31 deletions(-)

Index: linux/arch/x86/kernel/process_64.c
===================================================================
--- linux.orig/arch/x86/kernel/process_64.c
+++ linux/arch/x86/kernel/process_64.c
@@ -189,7 +189,10 @@ 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. */
Index: linux/arch/x86/lib/Makefile
===================================================================
--- linux.orig/arch/x86/lib/Makefile
+++ linux/arch/x86/lib/Makefile
@@ -12,6 +12,7 @@ ifeq ($(CONFIG_X86_32),y)
lib-y += checksum_32.o
lib-y += strstr_32.o
lib-y += bitops_32.o semaphore_32.o string_32.o
+ lib-y += thunk_32.o

lib-$(CONFIG_X86_USE_3DNOW) += mmx_32.o
else
Index: linux/arch/x86/lib/thunk_32.S
===================================================================
--- /dev/null
+++ linux/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
Index: linux/arch/x86/lib/thunk_64.S
===================================================================
--- linux.orig/arch/x86/lib/thunk_64.S
+++ linux/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.
*/

@@ -47,8 +48,22 @@
thunk __up_wakeup,__up

#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
Index: linux/include/asm-x86/irqflags.h
===================================================================
--- linux.orig/include/asm-x86/irqflags.h
+++ linux/include/asm-x86/irqflags.h
@@ -183,8 +183,6 @@ static inline void trace_hardirqs_fixup(
* 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; \
@@ -196,24 +194,6 @@ static inline void trace_hardirqs_fixup(
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; \
@@ -227,8 +207,8 @@ static inline void trace_hardirqs_fixup(
#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
Index: linux/include/linux/ftrace.h
===================================================================
--- linux.orig/include/linux/ftrace.h
+++ linux/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 */
Index: linux/include/linux/irqflags.h
===================================================================
--- linux.orig/include/linux/irqflags.h
+++ linux/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>
Index: linux/kernel/fork.c
===================================================================
--- linux.orig/kernel/fork.c
+++ linux/kernel/fork.c
@@ -1041,7 +1041,7 @@ static struct task_struct *copy_process(

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
Index: linux/kernel/lockdep.c
===================================================================
--- linux.orig/kernel/lockdep.c
+++ linux/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>

@@ -978,7 +979,7 @@ check_noncircular(struct lock_class *sou
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
@@ -1676,7 +1677,7 @@ valid_state(struct task_struct *curr, st
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:
@@ -2009,11 +2010,13 @@ 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;

@@ -2051,16 +2054,23 @@ 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;

@@ -2078,7 +2088,12 @@ 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);

/*
Index: linux/kernel/printk.c
===================================================================
--- linux.orig/kernel/printk.c
+++ linux/kernel/printk.c
@@ -990,7 +990,9 @@ 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;
Index: linux/kernel/trace/Kconfig
===================================================================
--- linux.orig/kernel/trace/Kconfig
+++ linux/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
Index: linux/kernel/trace/Makefile
===================================================================
--- linux.orig/kernel/trace/Makefile
+++ linux/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
Index: linux/kernel/trace/trace_irqsoff.c
===================================================================
--- /dev/null
+++ linux/kernel/trace/trace_irqsoff.c
@@ -0,0 +1,402 @@
+/*
+ * trace irqs off criticall timings
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@xxxxxxxxxx>
+ * Copyright (C) 2008 Ingo Molnar <mingo@xxxxxxxxxx>
+ *
+ * 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);
--
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