linux/kernel/trace/trace_syscalls.c
Linus Torvalds a7c180aa7e As the merge window is still open, and this code was not as complex
as I thought it might be. I'm pushing this in now.
 
 This will allow Thomas to debug his irq work for 3.20.
 
 This adds two new features:
 
 1) Allow traceopoints to be enabled right after mm_init(). By passing
 in the trace_event= kernel command line parameter, tracepoints can be
 enabled at boot up. For debugging things like the initialization of
 interrupts, it is needed to have tracepoints enabled very early. People
 have asked about this before and this has been on my todo list. As it
 can be helpful for Thomas to debug his upcoming 3.20 IRQ work, I'm
 pushing this now. This way he can add tracepoints into the IRQ set up
 and have users enable them when things go wrong.
 
 2) Have the tracepoints printed via printk() (the console) when they
 are triggered. If the irq code locks up or reboots the box, having the
 tracepoint output go into the kernel ring buffer is useless for
 debugging. But being able to add the tp_printk kernel command line
 option along with the trace_event= option will have these tracepoints
 printed as they occur, and that can be really useful for debugging
 early lock up or reboot problems.
 
 This code is not that intrusive and it passed all my tests. Thomas tried
 them out too and it works for his needs.
 
  Link: http://lkml.kernel.org/r/20141214201609.126831471@goodmis.org
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Merge tag 'trace-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "As the merge window is still open, and this code was not as complex as
  I thought it might be.  I'm pushing this in now.

  This will allow Thomas to debug his irq work for 3.20.

  This adds two new features:

  1) Allow traceopoints to be enabled right after mm_init().

     By passing in the trace_event= kernel command line parameter,
     tracepoints can be enabled at boot up.  For debugging things like
     the initialization of interrupts, it is needed to have tracepoints
     enabled very early.  People have asked about this before and this
     has been on my todo list.  As it can be helpful for Thomas to debug
     his upcoming 3.20 IRQ work, I'm pushing this now.  This way he can
     add tracepoints into the IRQ set up and have users enable them when
     things go wrong.

  2) Have the tracepoints printed via printk() (the console) when they
     are triggered.

     If the irq code locks up or reboots the box, having the tracepoint
     output go into the kernel ring buffer is useless for debugging.
     But being able to add the tp_printk kernel command line option
     along with the trace_event= option will have these tracepoints
     printed as they occur, and that can be really useful for debugging
     early lock up or reboot problems.

  This code is not that intrusive and it passed all my tests.  Thomas
  tried them out too and it works for his needs.

   Link: http://lkml.kernel.org/r/20141214201609.126831471@goodmis.org"

* tag 'trace-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Add tp_printk cmdline to have tracepoints go to printk()
  tracing: Move enabling tracepoints to just after rcu_init()
2014-12-16 12:53:59 -08:00

751 lines
18 KiB
C

#include <trace/syscall.h>
#include <trace/events/syscalls.h>
#include <linux/syscalls.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h> /* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */
#include <linux/ftrace.h>
#include <linux/perf_event.h>
#include <asm/syscall.h>
#include "trace_output.h"
#include "trace.h"
static DEFINE_MUTEX(syscall_trace_lock);
static int syscall_enter_register(struct ftrace_event_call *event,
enum trace_reg type, void *data);
static int syscall_exit_register(struct ftrace_event_call *event,
enum trace_reg type, void *data);
static struct list_head *
syscall_get_enter_fields(struct ftrace_event_call *call)
{
struct syscall_metadata *entry = call->data;
return &entry->enter_fields;
}
extern struct syscall_metadata *__start_syscalls_metadata[];
extern struct syscall_metadata *__stop_syscalls_metadata[];
static struct syscall_metadata **syscalls_metadata;
#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
{
/*
* Only compare after the "sys" prefix. Archs that use
* syscall wrappers may have syscalls symbols aliases prefixed
* with ".SyS" or ".sys" instead of "sys", leading to an unwanted
* mismatch.
*/
return !strcmp(sym + 3, name + 3);
}
#endif
#ifdef ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
/*
* Some architectures that allow for 32bit applications
* to run on a 64bit kernel, do not map the syscalls for
* the 32bit tasks the same as they do for 64bit tasks.
*
* *cough*x86*cough*
*
* In such a case, instead of reporting the wrong syscalls,
* simply ignore them.
*
* For an arch to ignore the compat syscalls it needs to
* define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS as well as
* define the function arch_trace_is_compat_syscall() to let
* the tracing system know that it should ignore it.
*/
static int
trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
{
if (unlikely(arch_trace_is_compat_syscall(regs)))
return -1;
return syscall_get_nr(task, regs);
}
#else
static inline int
trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
{
return syscall_get_nr(task, regs);
}
#endif /* ARCH_TRACE_IGNORE_COMPAT_SYSCALLS */
static __init struct syscall_metadata *
find_syscall_meta(unsigned long syscall)
{
struct syscall_metadata **start;
struct syscall_metadata **stop;
char str[KSYM_SYMBOL_LEN];
start = __start_syscalls_metadata;
stop = __stop_syscalls_metadata;
kallsyms_lookup(syscall, NULL, NULL, NULL, str);
if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
return NULL;
for ( ; start < stop; start++) {
if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
return *start;
}
return NULL;
}
static struct syscall_metadata *syscall_nr_to_meta(int nr)
{
if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
return NULL;
return syscalls_metadata[nr];
}
static enum print_line_t
print_syscall_enter(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *ent = iter->ent;
struct syscall_trace_enter *trace;
struct syscall_metadata *entry;
int i, syscall;
trace = (typeof(trace))ent;
syscall = trace->nr;
entry = syscall_nr_to_meta(syscall);
if (!entry)
goto end;
if (entry->enter_event->event.type != ent->type) {
WARN_ON_ONCE(1);
goto end;
}
trace_seq_printf(s, "%s(", entry->name);
for (i = 0; i < entry->nb_args; i++) {
if (trace_seq_has_overflowed(s))
goto end;
/* parameter types */
if (trace_flags & TRACE_ITER_VERBOSE)
trace_seq_printf(s, "%s ", entry->types[i]);
/* parameter values */
trace_seq_printf(s, "%s: %lx%s", entry->args[i],
trace->args[i],
i == entry->nb_args - 1 ? "" : ", ");
}
trace_seq_putc(s, ')');
end:
trace_seq_putc(s, '\n');
return trace_handle_return(s);
}
static enum print_line_t
print_syscall_exit(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *ent = iter->ent;
struct syscall_trace_exit *trace;
int syscall;
struct syscall_metadata *entry;
trace = (typeof(trace))ent;
syscall = trace->nr;
entry = syscall_nr_to_meta(syscall);
if (!entry) {
trace_seq_putc(s, '\n');
goto out;
}
if (entry->exit_event->event.type != ent->type) {
WARN_ON_ONCE(1);
return TRACE_TYPE_UNHANDLED;
}
trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
trace->ret);
out:
return trace_handle_return(s);
}
extern char *__bad_type_size(void);
#define SYSCALL_FIELD(type, name) \
sizeof(type) != sizeof(trace.name) ? \
__bad_type_size() : \
#type, #name, offsetof(typeof(trace), name), \
sizeof(trace.name), is_signed_type(type)
static int __init
__set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
{
int i;
int pos = 0;
/* When len=0, we just calculate the needed length */
#define LEN_OR_ZERO (len ? len - pos : 0)
pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
for (i = 0; i < entry->nb_args; i++) {
pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
entry->args[i], sizeof(unsigned long),
i == entry->nb_args - 1 ? "" : ", ");
}
pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
for (i = 0; i < entry->nb_args; i++) {
pos += snprintf(buf + pos, LEN_OR_ZERO,
", ((unsigned long)(REC->%s))", entry->args[i]);
}
#undef LEN_OR_ZERO
/* return the length of print_fmt */
return pos;
}
static int __init set_syscall_print_fmt(struct ftrace_event_call *call)
{
char *print_fmt;
int len;
struct syscall_metadata *entry = call->data;
if (entry->enter_event != call) {
call->print_fmt = "\"0x%lx\", REC->ret";
return 0;
}
/* First: called with 0 length to calculate the needed length */
len = __set_enter_print_fmt(entry, NULL, 0);
print_fmt = kmalloc(len + 1, GFP_KERNEL);
if (!print_fmt)
return -ENOMEM;
/* Second: actually write the @print_fmt */
__set_enter_print_fmt(entry, print_fmt, len + 1);
call->print_fmt = print_fmt;
return 0;
}
static void __init free_syscall_print_fmt(struct ftrace_event_call *call)
{
struct syscall_metadata *entry = call->data;
if (entry->enter_event == call)
kfree(call->print_fmt);
}
static int __init syscall_enter_define_fields(struct ftrace_event_call *call)
{
struct syscall_trace_enter trace;
struct syscall_metadata *meta = call->data;
int ret;
int i;
int offset = offsetof(typeof(trace), args);
ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
if (ret)
return ret;
for (i = 0; i < meta->nb_args; i++) {
ret = trace_define_field(call, meta->types[i],
meta->args[i], offset,
sizeof(unsigned long), 0,
FILTER_OTHER);
offset += sizeof(unsigned long);
}
return ret;
}
static int __init syscall_exit_define_fields(struct ftrace_event_call *call)
{
struct syscall_trace_exit trace;
int ret;
ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
if (ret)
return ret;
ret = trace_define_field(call, SYSCALL_FIELD(long, ret),
FILTER_OTHER);
return ret;
}
static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
{
struct trace_array *tr = data;
struct ftrace_event_file *ftrace_file;
struct syscall_trace_enter *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
unsigned long irq_flags;
int pc;
int syscall_nr;
int size;
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
return;
/* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
ftrace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
if (!ftrace_file)
return;
if (ftrace_trigger_soft_disabled(ftrace_file))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
local_save_flags(irq_flags);
pc = preempt_count();
buffer = tr->trace_buffer.buffer;
event = trace_buffer_lock_reserve(buffer,
sys_data->enter_event->event.type, size, irq_flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->nr = syscall_nr;
syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
event_trigger_unlock_commit(ftrace_file, buffer, event, entry,
irq_flags, pc);
}
static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
{
struct trace_array *tr = data;
struct ftrace_event_file *ftrace_file;
struct syscall_trace_exit *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
unsigned long irq_flags;
int pc;
int syscall_nr;
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
return;
/* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */
ftrace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]);
if (!ftrace_file)
return;
if (ftrace_trigger_soft_disabled(ftrace_file))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
local_save_flags(irq_flags);
pc = preempt_count();
buffer = tr->trace_buffer.buffer;
event = trace_buffer_lock_reserve(buffer,
sys_data->exit_event->event.type, sizeof(*entry),
irq_flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->nr = syscall_nr;
entry->ret = syscall_get_return_value(current, regs);
event_trigger_unlock_commit(ftrace_file, buffer, event, entry,
irq_flags, pc);
}
static int reg_event_syscall_enter(struct ftrace_event_file *file,
struct ftrace_event_call *call)
{
struct trace_array *tr = file->tr;
int ret = 0;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
return -ENOSYS;
mutex_lock(&syscall_trace_lock);
if (!tr->sys_refcount_enter)
ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
if (!ret) {
rcu_assign_pointer(tr->enter_syscall_files[num], file);
tr->sys_refcount_enter++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}
static void unreg_event_syscall_enter(struct ftrace_event_file *file,
struct ftrace_event_call *call)
{
struct trace_array *tr = file->tr;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
return;
mutex_lock(&syscall_trace_lock);
tr->sys_refcount_enter--;
RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL);
if (!tr->sys_refcount_enter)
unregister_trace_sys_enter(ftrace_syscall_enter, tr);
mutex_unlock(&syscall_trace_lock);
}
static int reg_event_syscall_exit(struct ftrace_event_file *file,
struct ftrace_event_call *call)
{
struct trace_array *tr = file->tr;
int ret = 0;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
return -ENOSYS;
mutex_lock(&syscall_trace_lock);
if (!tr->sys_refcount_exit)
ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
if (!ret) {
rcu_assign_pointer(tr->exit_syscall_files[num], file);
tr->sys_refcount_exit++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}
static void unreg_event_syscall_exit(struct ftrace_event_file *file,
struct ftrace_event_call *call)
{
struct trace_array *tr = file->tr;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
return;
mutex_lock(&syscall_trace_lock);
tr->sys_refcount_exit--;
RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL);
if (!tr->sys_refcount_exit)
unregister_trace_sys_exit(ftrace_syscall_exit, tr);
mutex_unlock(&syscall_trace_lock);
}
static int __init init_syscall_trace(struct ftrace_event_call *call)
{
int id;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
if (num < 0 || num >= NR_syscalls) {
pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
((struct syscall_metadata *)call->data)->name);
return -ENOSYS;
}
if (set_syscall_print_fmt(call) < 0)
return -ENOMEM;
id = trace_event_raw_init(call);
if (id < 0) {
free_syscall_print_fmt(call);
return id;
}
return id;
}
struct trace_event_functions enter_syscall_print_funcs = {
.trace = print_syscall_enter,
};
struct trace_event_functions exit_syscall_print_funcs = {
.trace = print_syscall_exit,
};
struct ftrace_event_class __refdata event_class_syscall_enter = {
.system = "syscalls",
.reg = syscall_enter_register,
.define_fields = syscall_enter_define_fields,
.get_fields = syscall_get_enter_fields,
.raw_init = init_syscall_trace,
};
struct ftrace_event_class __refdata event_class_syscall_exit = {
.system = "syscalls",
.reg = syscall_exit_register,
.define_fields = syscall_exit_define_fields,
.fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),
.raw_init = init_syscall_trace,
};
unsigned long __init __weak arch_syscall_addr(int nr)
{
return (unsigned long)sys_call_table[nr];
}
void __init init_ftrace_syscalls(void)
{
struct syscall_metadata *meta;
unsigned long addr;
int i;
syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata),
GFP_KERNEL);
if (!syscalls_metadata) {
WARN_ON(1);
return;
}
for (i = 0; i < NR_syscalls; i++) {
addr = arch_syscall_addr(i);
meta = find_syscall_meta(addr);
if (!meta)
continue;
meta->syscall_nr = i;
syscalls_metadata[i] = meta;
}
}
#ifdef CONFIG_PERF_EVENTS
static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
static int sys_perf_refcount_enter;
static int sys_perf_refcount_exit;
static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
{
struct syscall_metadata *sys_data;
struct syscall_trace_enter *rec;
struct hlist_head *head;
int syscall_nr;
int rctx;
int size;
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
return;
if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
head = this_cpu_ptr(sys_data->enter_event->perf_events);
if (hlist_empty(head))
return;
/* get the size after alignment with the u32 buffer size field */
size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
size = ALIGN(size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
sys_data->enter_event->event.type, regs, &rctx);
if (!rec)
return;
rec->nr = syscall_nr;
syscall_get_arguments(current, regs, 0, sys_data->nb_args,
(unsigned long *)&rec->args);
perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
}
static int perf_sysenter_enable(struct ftrace_event_call *call)
{
int ret = 0;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
mutex_lock(&syscall_trace_lock);
if (!sys_perf_refcount_enter)
ret = register_trace_sys_enter(perf_syscall_enter, NULL);
if (ret) {
pr_info("event trace: Could not activate"
"syscall entry trace point");
} else {
set_bit(num, enabled_perf_enter_syscalls);
sys_perf_refcount_enter++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}
static void perf_sysenter_disable(struct ftrace_event_call *call)
{
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
mutex_lock(&syscall_trace_lock);
sys_perf_refcount_enter--;
clear_bit(num, enabled_perf_enter_syscalls);
if (!sys_perf_refcount_enter)
unregister_trace_sys_enter(perf_syscall_enter, NULL);
mutex_unlock(&syscall_trace_lock);
}
static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
{
struct syscall_metadata *sys_data;
struct syscall_trace_exit *rec;
struct hlist_head *head;
int syscall_nr;
int rctx;
int size;
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
return;
if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
if (!sys_data)
return;
head = this_cpu_ptr(sys_data->exit_event->perf_events);
if (hlist_empty(head))
return;
/* We can probably do that at build time */
size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
sys_data->exit_event->event.type, regs, &rctx);
if (!rec)
return;
rec->nr = syscall_nr;
rec->ret = syscall_get_return_value(current, regs);
perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
}
static int perf_sysexit_enable(struct ftrace_event_call *call)
{
int ret = 0;
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
mutex_lock(&syscall_trace_lock);
if (!sys_perf_refcount_exit)
ret = register_trace_sys_exit(perf_syscall_exit, NULL);
if (ret) {
pr_info("event trace: Could not activate"
"syscall exit trace point");
} else {
set_bit(num, enabled_perf_exit_syscalls);
sys_perf_refcount_exit++;
}
mutex_unlock(&syscall_trace_lock);
return ret;
}
static void perf_sysexit_disable(struct ftrace_event_call *call)
{
int num;
num = ((struct syscall_metadata *)call->data)->syscall_nr;
mutex_lock(&syscall_trace_lock);
sys_perf_refcount_exit--;
clear_bit(num, enabled_perf_exit_syscalls);
if (!sys_perf_refcount_exit)
unregister_trace_sys_exit(perf_syscall_exit, NULL);
mutex_unlock(&syscall_trace_lock);
}
#endif /* CONFIG_PERF_EVENTS */
static int syscall_enter_register(struct ftrace_event_call *event,
enum trace_reg type, void *data)
{
struct ftrace_event_file *file = data;
switch (type) {
case TRACE_REG_REGISTER:
return reg_event_syscall_enter(file, event);
case TRACE_REG_UNREGISTER:
unreg_event_syscall_enter(file, event);
return 0;
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
return perf_sysenter_enable(event);
case TRACE_REG_PERF_UNREGISTER:
perf_sysenter_disable(event);
return 0;
case TRACE_REG_PERF_OPEN:
case TRACE_REG_PERF_CLOSE:
case TRACE_REG_PERF_ADD:
case TRACE_REG_PERF_DEL:
return 0;
#endif
}
return 0;
}
static int syscall_exit_register(struct ftrace_event_call *event,
enum trace_reg type, void *data)
{
struct ftrace_event_file *file = data;
switch (type) {
case TRACE_REG_REGISTER:
return reg_event_syscall_exit(file, event);
case TRACE_REG_UNREGISTER:
unreg_event_syscall_exit(file, event);
return 0;
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
return perf_sysexit_enable(event);
case TRACE_REG_PERF_UNREGISTER:
perf_sysexit_disable(event);
return 0;
case TRACE_REG_PERF_OPEN:
case TRACE_REG_PERF_CLOSE:
case TRACE_REG_PERF_ADD:
case TRACE_REG_PERF_DEL:
return 0;
#endif
}
return 0;
}