ftrace: Have global_ops store the functions that are to be traced
[linux-2.6.git] / kernel / trace / trace_syscalls.c
index 66cf974..ee7b5a0 100644 (file)
-#include <linux/ftrace.h>
+#include <trace/syscall.h>
+#include <trace/events/syscalls.h>
+#include <linux/slab.h>
 #include <linux/kernel.h>
-
+#include <linux/ftrace.h>
+#include <linux/perf_event.h>
 #include <asm/syscall.h>
 
 #include "trace_output.h"
 #include "trace.h"
 
-static atomic_t refcount;
+static DEFINE_MUTEX(syscall_trace_lock);
+static int sys_refcount_enter;
+static int sys_refcount_exit;
+static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
+static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
+
+static int syscall_enter_register(struct ftrace_event_call *event,
+                                enum trace_reg type);
+static int syscall_exit_register(struct ftrace_event_call *event,
+                                enum trace_reg type);
+
+static int syscall_enter_define_fields(struct ftrace_event_call *call);
+static int syscall_exit_define_fields(struct ftrace_event_call *call);
+
+static struct list_head *
+syscall_get_enter_fields(struct ftrace_event_call *call)
+{
+       struct syscall_metadata *entry = call->data;
+
+       return &entry->enter_fields;
+}
+
+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 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 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,
+};
+
+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" instead of "sys", leading to an unwanted
+        * mismatch.
+        */
+       return !strcmp(sym + 3, name + 3);
+}
+#endif
+
+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];
+}
+
+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, ret, 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;
+       }
+
+       ret = trace_seq_printf(s, "%s(", entry->name);
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
+       for (i = 0; i < entry->nb_args; i++) {
+               /* parameter types */
+               if (trace_flags & TRACE_ITER_VERBOSE) {
+                       ret = trace_seq_printf(s, "%s ", entry->types[i]);
+                       if (!ret)
+                               return TRACE_TYPE_PARTIAL_LINE;
+               }
+               /* parameter values */
+               ret = trace_seq_printf(s, "%s: %lx%s", entry->args[i],
+                                      trace->args[i],
+                                      i == entry->nb_args - 1 ? "" : ", ");
+               if (!ret)
+                       return TRACE_TYPE_PARTIAL_LINE;
+       }
+
+       ret = trace_seq_putc(s, ')');
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
+end:
+       ret =  trace_seq_putc(s, '\n');
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
+       return TRACE_TYPE_HANDLED;
+}
+
+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;
+       int ret;
+
+       trace = (typeof(trace))ent;
+       syscall = trace->nr;
+       entry = syscall_nr_to_meta(syscall);
+
+       if (!entry) {
+               trace_seq_printf(s, "\n");
+               return TRACE_TYPE_HANDLED;
+       }
+
+       if (entry->exit_event->event.type != ent->type) {
+               WARN_ON_ONCE(1);
+               return TRACE_TYPE_UNHANDLED;
+       }
+
+       ret = trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
+                               trace->ret);
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
+       return TRACE_TYPE_HANDLED;
+}
+
+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)
 
-void start_ftrace_syscalls(void)
+static
+int  __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
 {
-       unsigned long flags;
-       struct task_struct *g, *t;
+       int i;
+       int pos = 0;
 
-       if (atomic_inc_return(&refcount) != 1)
-               goto out;
+       /* When len=0, we just calculate the needed length */
+#define LEN_OR_ZERO (len ? len - pos : 0)
 
-       read_lock_irqsave(&tasklist_lock, flags);
+       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]);
+       }
 
-       do_each_thread(g, t) {
-               set_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
-       } while_each_thread(g, t);
+#undef LEN_OR_ZERO
 
-       read_unlock_irqrestore(&tasklist_lock, flags);
-out:
-       atomic_dec(&refcount);
+       /* return the length of print_fmt */
+       return pos;
 }
 
-void stop_ftrace_syscalls(void)
+static int set_syscall_print_fmt(struct ftrace_event_call *call)
 {
-       unsigned long flags;
-       struct task_struct *g, *t;
+       char *print_fmt;
+       int len;
+       struct syscall_metadata *entry = call->data;
 
-       if (atomic_dec_return(&refcount))
-               goto out;
+       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);
 
-       read_lock_irqsave(&tasklist_lock, flags);
+       print_fmt = kmalloc(len + 1, GFP_KERNEL);
+       if (!print_fmt)
+               return -ENOMEM;
 
-       do_each_thread(g, t) {
-               clear_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
-       } while_each_thread(g, t);
+       /* Second: actually write the @print_fmt */
+       __set_enter_print_fmt(entry, print_fmt, len + 1);
+       call->print_fmt = print_fmt;
 
-       read_unlock_irqrestore(&tasklist_lock, flags);
-out:
-       atomic_inc(&refcount);
+       return 0;
 }
 
-void ftrace_syscall_enter(struct pt_regs *regs)
+static void 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 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 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;
+}
+
+void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)
+{
+       struct syscall_trace_enter *entry;
+       struct syscall_metadata *sys_data;
+       struct ring_buffer_event *event;
+       struct ring_buffer *buffer;
+       int size;
        int syscall_nr;
 
        syscall_nr = syscall_get_nr(current, regs);
+       if (syscall_nr < 0)
+               return;
+       if (!test_bit(syscall_nr, enabled_enter_syscalls))
+               return;
+
+       sys_data = syscall_nr_to_meta(syscall_nr);
+       if (!sys_data)
+               return;
+
+       size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
 
-       trace_printk("syscall %d enter\n", syscall_nr);
+       event = trace_current_buffer_lock_reserve(&buffer,
+                       sys_data->enter_event->event.type, size, 0, 0);
+       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);
+
+       if (!filter_current_check_discard(buffer, sys_data->enter_event,
+                                         entry, event))
+               trace_current_buffer_unlock_commit(buffer, event, 0, 0);
 }
 
-void ftrace_syscall_exit(struct pt_regs *regs)
+void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 {
+       struct syscall_trace_exit *entry;
+       struct syscall_metadata *sys_data;
+       struct ring_buffer_event *event;
+       struct ring_buffer *buffer;
        int syscall_nr;
 
        syscall_nr = syscall_get_nr(current, regs);
+       if (syscall_nr < 0)
+               return;
+       if (!test_bit(syscall_nr, enabled_exit_syscalls))
+               return;
+
+       sys_data = syscall_nr_to_meta(syscall_nr);
+       if (!sys_data)
+               return;
+
+       event = trace_current_buffer_lock_reserve(&buffer,
+                       sys_data->exit_event->event.type, sizeof(*entry), 0, 0);
+       if (!event)
+               return;
+
+       entry = ring_buffer_event_data(event);
+       entry->nr = syscall_nr;
+       entry->ret = syscall_get_return_value(current, regs);
 
-       trace_printk("syscall %d exit\n", syscall_nr);
+       if (!filter_current_check_discard(buffer, sys_data->exit_event,
+                                         entry, event))
+               trace_current_buffer_unlock_commit(buffer, event, 0, 0);
 }
 
-static int init_syscall_tracer(struct trace_array *tr)
+int reg_event_syscall_enter(struct ftrace_event_call *call)
 {
-       start_ftrace_syscalls();
+       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 (!sys_refcount_enter)
+               ret = register_trace_sys_enter(ftrace_syscall_enter, NULL);
+       if (!ret) {
+               set_bit(num, enabled_enter_syscalls);
+               sys_refcount_enter++;
+       }
+       mutex_unlock(&syscall_trace_lock);
+       return ret;
+}
+
+void unreg_event_syscall_enter(struct ftrace_event_call *call)
+{
+       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);
+       sys_refcount_enter--;
+       clear_bit(num, enabled_enter_syscalls);
+       if (!sys_refcount_enter)
+               unregister_trace_sys_enter(ftrace_syscall_enter, NULL);
+       mutex_unlock(&syscall_trace_lock);
+}
+
+int reg_event_syscall_exit(struct ftrace_event_call *call)
+{
+       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 (!sys_refcount_exit)
+               ret = register_trace_sys_exit(ftrace_syscall_exit, NULL);
+       if (!ret) {
+               set_bit(num, enabled_exit_syscalls);
+               sys_refcount_exit++;
+       }
+       mutex_unlock(&syscall_trace_lock);
+       return ret;
+}
+
+void unreg_event_syscall_exit(struct ftrace_event_call *call)
+{
+       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);
+       sys_refcount_exit--;
+       clear_bit(num, enabled_exit_syscalls);
+       if (!sys_refcount_exit)
+               unregister_trace_sys_exit(ftrace_syscall_exit, NULL);
+       mutex_unlock(&syscall_trace_lock);
+}
+
+int 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;
+}
+
+unsigned long __init __weak arch_syscall_addr(int nr)
+{
+       return (unsigned long)sys_call_table[nr];
+}
+
+int __init init_ftrace_syscalls(void)
+{
+       struct syscall_metadata *meta;
+       unsigned long addr;
+       int i;
+
+       syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
+                                       NR_syscalls, GFP_KERNEL);
+       if (!syscalls_metadata) {
+               WARN_ON(1);
+               return -ENOMEM;
+       }
+
+       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;
+       }
 
        return 0;
 }
+core_initcall(init_ftrace_syscalls);
+
+#ifdef CONFIG_PERF_EVENTS
 
-static void reset_syscall_tracer(struct trace_array *tr)
+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)
 {
-       stop_ftrace_syscalls();
+       struct syscall_metadata *sys_data;
+       struct syscall_trace_enter *rec;
+       struct hlist_head *head;
+       int syscall_nr;
+       int rctx;
+       int size;
+
+       syscall_nr = syscall_get_nr(current, regs);
+       if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
+               return;
+
+       sys_data = syscall_nr_to_meta(syscall_nr);
+       if (!sys_data)
+               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);
+
+       if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
+                     "perf buffer not large enough"))
+               return;
+
+       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);
+
+       head = this_cpu_ptr(sys_data->enter_event->perf_events);
+       perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
 }
 
-static struct trace_event syscall_enter_event = {
-       .type           = TRACE_SYSCALL_ENTER,
-};
+int perf_sysenter_enable(struct ftrace_event_call *call)
+{
+       int ret = 0;
+       int num;
 
-static struct trace_event syscall_exit_event = {
-       .type           = TRACE_SYSCALL_EXIT,
-};
+       num = ((struct syscall_metadata *)call->data)->syscall_nr;
 
-static struct tracer syscall_tracer __read_mostly = {
-       .name           = "syscall",
-       .init           = init_syscall_tracer,
-       .reset          = reset_syscall_tracer
-};
+       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;
+}
 
-__init int register_ftrace_syscalls(void)
+void perf_sysenter_disable(struct ftrace_event_call *call)
 {
-       int ret;
+       int num;
 
-       ret = register_ftrace_event(&syscall_enter_event);
-       if (!ret) {
-               printk(KERN_WARNING "event %d failed to register\n",
-                      syscall_enter_event.type);
-               WARN_ON_ONCE(1);
+       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 = syscall_get_nr(current, regs);
+       if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
+               return;
+
+       sys_data = syscall_nr_to_meta(syscall_nr);
+       if (!sys_data)
+               return;
+
+       /* We can probably do that at build time */
+       size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
+       size -= sizeof(u32);
+
+       /*
+        * Impossible, but be paranoid with the future
+        * How to put this check outside runtime?
+        */
+       if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
+               "exit event has grown above perf buffer size"))
+               return;
+
+       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);
+
+       head = this_cpu_ptr(sys_data->exit_event->perf_events);
+       perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
+}
+
+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;
+}
 
-       ret = register_ftrace_event(&syscall_exit_event);
-       if (!ret) {
-               printk(KERN_WARNING "event %d failed to register\n",
-                      syscall_exit_event.type);
-               WARN_ON_ONCE(1);
+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)
+{
+       switch (type) {
+       case TRACE_REG_REGISTER:
+               return reg_event_syscall_enter(event);
+       case TRACE_REG_UNREGISTER:
+               unreg_event_syscall_enter(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;
+#endif
        }
+       return 0;
+}
+
+static int syscall_exit_register(struct ftrace_event_call *event,
+                                enum trace_reg type)
+{
+       switch (type) {
+       case TRACE_REG_REGISTER:
+               return reg_event_syscall_exit(event);
+       case TRACE_REG_UNREGISTER:
+               unreg_event_syscall_exit(event);
+               return 0;
 
-       return register_tracer(&syscall_tracer);
+#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;
+#endif
+       }
+       return 0;
 }
-device_initcall(register_ftrace_syscalls);