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21e92806d3
mirror_ubuntu-kernels/kernel/trace/trace_irqsoff.c
Donglin Peng 21e92806d3 function_graph: Support recording and printing the function return address 
When using function_graph tracer to analyze the flow of kernel function
execution, it is often necessary to quickly locate the exact line of code
where the call occurs. While this may be easy at times, it can be more
time-consuming when some functions are inlined or the flow is too long.

This feature aims to simplify the process by recording the return address
of traced funcions and printing it when outputing trace logs.

To enhance human readability, the prefix 'ret=' is used for the kernel return
value, while '<-' serves as the prefix for the return address in trace logs to
make it look more like the function tracer.

A new trace option named 'funcgraph-retaddr' has been introduced, and the
existing option 'sym-addr' can be used to control the format of the return
address.

See below logs with both funcgraph-retval and funcgraph-retaddr enabled.

0)             | load_elf_binary() { /* <-bprm_execve+0x249/0x600 */
0)             |   load_elf_phdrs() { /* <-load_elf_binary+0x84/0x1730 */
0)             |     __kmalloc_noprof() { /* <-load_elf_phdrs+0x4a/0xb0 */
0)   3.657 us  |       __cond_resched(); /* <-__kmalloc_noprof+0x28c/0x390 ret=0x0 */
0) + 24.335 us |     } /* __kmalloc_noprof ret=0xffff8882007f3000 */
0)             |     kernel_read() { /* <-load_elf_phdrs+0x6c/0xb0 */
0)             |       rw_verify_area() { /* <-kernel_read+0x2b/0x50 */
0)             |         security_file_permission() { /* <-kernel_read+0x2b/0x50 */
0)             |           selinux_file_permission() { /* <-security_file_permission+0x26/0x40 */
0)             |             __inode_security_revalidate() { /* <-selinux_file_permission+0x6d/0x140 */
0)   2.034 us  |               __cond_resched(); /* <-__inode_security_revalidate+0x5f/0x80 ret=0x0 */
0)   6.602 us  |             } /* __inode_security_revalidate ret=0x0 */
0)   2.214 us  |             avc_policy_seqno(); /* <-selinux_file_permission+0x107/0x140 ret=0x0 */
0) + 16.670 us |           } /* selinux_file_permission ret=0x0 */
0) + 20.809 us |         } /* security_file_permission ret=0x0 */
0) + 25.217 us |       } /* rw_verify_area ret=0x0 */
0)             |       __kernel_read() { /* <-load_elf_phdrs+0x6c/0xb0 */
0)             |         ext4_file_read_iter() { /* <-__kernel_read+0x160/0x2e0 */

Then, we can use the faddr2line to locate the source code, for example:

$ ./scripts/faddr2line ./vmlinux load_elf_phdrs+0x6c/0xb0
load_elf_phdrs+0x6c/0xb0:
elf_read at fs/binfmt_elf.c:471
(inlined by) load_elf_phdrs at fs/binfmt_elf.c:531

Link: https://lore.kernel.org/20240915032912.1118397-1-dolinux.peng@gmail.com
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409150605.HgUmU8ea-lkp@intel.com/
Signed-off-by: Donglin Peng <dolinux.peng@gmail.com>
[ Rebased to handle text_delta offsets ]
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2024-10-05 10:14:04 -04:00

756 lines
18 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0
/*
* 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 <linux/kprobes.h>
#include "trace.h"
#include <trace/events/preemptirq.h>
#if defined(CONFIG_IRQSOFF_TRACER) || defined(CONFIG_PREEMPT_TRACER)
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(int pc)
{
return ((trace_type & TRACER_PREEMPT_OFF) && pc);
}
#else
# define preempt_trace(pc) (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->array_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 ftrace_regs *fregs)
{
struct trace_array *tr = irqsoff_trace;
struct trace_array_cpu *data;
unsigned long flags;
unsigned int trace_ctx;
if (!func_prolog_dec(tr, &data, &flags))
return;
trace_ctx = tracing_gen_ctx_flags(flags);
trace_function(tr, ip, parent_ip, trace_ctx);
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->array_buffer);
return start_irqsoff_tracer(irqsoff_trace, set);
}
static int irqsoff_graph_entry(struct ftrace_graph_ent *trace,
struct fgraph_ops *gops,
struct fgraph_extras *extras)
{
struct trace_array *tr = irqsoff_trace;
struct trace_array_cpu *data;
unsigned long flags;
unsigned int trace_ctx;
int ret;
if (ftrace_graph_ignore_func(gops, trace))
return 0;
/*
* Do not trace a function if it's filtered by set_graph_notrace.
* Make the index of ret stack negative to indicate that it should
* ignore further functions. But it needs its own ret stack entry
* to recover the original index in order to continue tracing after
* returning from the function.
*/
if (ftrace_graph_notrace_addr(trace->func))
return 1;
if (!func_prolog_dec(tr, &data, &flags))
return 0;
trace_ctx = tracing_gen_ctx_flags(flags);
ret = __trace_graph_entry(tr, trace, trace_ctx);
atomic_dec(&data->disabled);
return ret;
}
static void irqsoff_graph_return(struct ftrace_graph_ret *trace,
struct fgraph_ops *gops)
{
struct trace_array *tr = irqsoff_trace;
struct trace_array_cpu *data;
unsigned long flags;
unsigned int trace_ctx;
ftrace_graph_addr_finish(gops, trace);
if (!func_prolog_dec(tr, &data, &flags))
return;
trace_ctx = tracing_gen_ctx_flags(flags);
__trace_graph_return(tr, trace, trace_ctx);
atomic_dec(&data->disabled);
}
static struct fgraph_ops fgraph_ops = {
.entryfunc = &irqsoff_graph_entry,
.retfunc = &irqsoff_graph_return,
};
static void irqsoff_trace_open(struct trace_iterator *iter)
{
if (is_graph(iter->tr))
graph_trace_open(iter);
else
iter->private = NULL;
}
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_REL_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 int trace_ctx)
{
if (is_graph(tr))
trace_graph_function(tr, ip, parent_ip, trace_ctx);
else
trace_function(tr, ip, parent_ip, trace_ctx);
}
#else
#define __trace_function trace_function
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_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, u64 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)
{
u64 T0, T1, delta;
unsigned long flags;
unsigned int trace_ctx;
T0 = data->preempt_timestamp;
T1 = ftrace_now(cpu);
delta = T1-T0;
trace_ctx = tracing_gen_ctx();
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, trace_ctx);
/* Skip 5 functions to get to the irq/preempt enable function */
__trace_stack(tr, trace_ctx, 5);
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, trace_ctx);
}
static nokprobe_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;
if (!tracer_enabled || !tracing_is_enabled())
return;
cpu = raw_smp_processor_id();
if (per_cpu(tracing_cpu, cpu))
return;
data = per_cpu_ptr(tr->array_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;
__trace_function(tr, ip, parent_ip, tracing_gen_ctx());
per_cpu(tracing_cpu, cpu) = 1;
atomic_dec(&data->disabled);
}
static nokprobe_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 int trace_ctx;
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->array_buffer.data, cpu);
if (unlikely(!data) ||
!data->critical_start || atomic_read(&data->disabled))
return;
atomic_inc(&data->disabled);
trace_ctx = tracing_gen_ctx();
__trace_function(tr, ip, parent_ip, trace_ctx);
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(preempt_count()) || irq_trace())
start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
}
EXPORT_SYMBOL_GPL(start_critical_timings);
NOKPROBE_SYMBOL(start_critical_timings);
void stop_critical_timings(void)
{
if (preempt_trace(preempt_count()) || irq_trace())
stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
}
EXPORT_SYMBOL_GPL(stop_critical_timings);
NOKPROBE_SYMBOL(stop_critical_timings);
#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(&fgraph_ops);
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(&fgraph_ops);
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);
/* without pause, we will produce garbage if another latency occurs */
set_tracer_flag(tr, TRACE_ITER_PAUSE_ON_TRACE, 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\n");
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;
int pause_flag = save_flags & TRACE_ITER_PAUSE_ON_TRACE;
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);
set_tracer_flag(tr, TRACE_ITER_PAUSE_ON_TRACE, pause_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
/*
* We are only interested in hardirq on/off events:
*/
void tracer_hardirqs_on(unsigned long a0, unsigned long a1)
{
if (!preempt_trace(preempt_count()) && irq_trace())
stop_critical_timing(a0, a1);
}
NOKPROBE_SYMBOL(tracer_hardirqs_on);
void tracer_hardirqs_off(unsigned long a0, unsigned long a1)
{
if (!preempt_trace(preempt_count()) && irq_trace())
start_critical_timing(a0, a1);
}
NOKPROBE_SYMBOL(tracer_hardirqs_off);
static int irqsoff_tracer_init(struct trace_array *tr)
{
trace_type = TRACER_IRQS_OFF;
return __irqsoff_tracer_init(tr);
}
static void irqsoff_tracer_reset(struct trace_array *tr)
{
__irqsoff_tracer_reset(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,
};
#endif /* CONFIG_IRQSOFF_TRACER */
#ifdef CONFIG_PREEMPT_TRACER
void tracer_preempt_on(unsigned long a0, unsigned long a1)
{
if (preempt_trace(preempt_count()) && !irq_trace())
stop_critical_timing(a0, a1);
}
void tracer_preempt_off(unsigned long a0, unsigned long a1)
{
if (preempt_trace(preempt_count()) && !irq_trace())
start_critical_timing(a0, a1);
}
static int preemptoff_tracer_init(struct trace_array *tr)
{
trace_type = TRACER_PREEMPT_OFF;
return __irqsoff_tracer_init(tr);
}
static void preemptoff_tracer_reset(struct trace_array *tr)
{
__irqsoff_tracer_reset(tr);
}
static struct tracer preemptoff_tracer __read_mostly =
{
.name = "preemptoff",
.init = preemptoff_tracer_init,
.reset = preemptoff_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,
};
#endif /* CONFIG_PREEMPT_TRACER */
#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 void preemptirqsoff_tracer_reset(struct trace_array *tr)
{
__irqsoff_tracer_reset(tr);
}
static struct tracer preemptirqsoff_tracer __read_mostly =
{
.name = "preemptirqsoff",
.init = preemptirqsoff_tracer_init,
.reset = preemptirqsoff_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,
};
#endif
__init static int init_irqsoff_tracer(void)
{
#ifdef CONFIG_IRQSOFF_TRACER
register_tracer(&irqsoff_tracer);
#endif
#ifdef CONFIG_PREEMPT_TRACER
register_tracer(&preemptoff_tracer);
#endif
#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
register_tracer(&preemptirqsoff_tracer);
#endif
return 0;
}
core_initcall(init_irqsoff_tracer);
#endif /* IRQSOFF_TRACER || PREEMPTOFF_TRACER */
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