tracing/syscalls: Add filtering support

Add filtering support for syscall events:

 # echo 'mode == 0666' > events/syscalls/sys_enter_open
 # echo 'ret == 0' > events/syscalls/sys_exit_open
 # echo 1 > events/syscalls/sys_enter_open
 # echo 1 > events/syscalls/sys_exit_open
 # cat trace
 ...
   modprobe-3084 [001] 117.463140: sys_open(filename: 917d3e8, flags: 0, mode: 1b6)
   modprobe-3084 [001] 117.463176: sys_open -> 0x0
       less-3086 [001] 117.510455: sys_open(filename: 9c6bdb8, flags: 8000, mode: 1b6)
   sendmail-2574 [001] 122.145840: sys_open(filename: b807a365, flags: 0, mode: 1b6)
 ...

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A8BAFCB.1040006@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 21 insertions, 7 deletions

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 427cbae47f84..df5b085c4150 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -140,8 +140,9 @@ extern int filter_current_check_discard(struct ftrace_event_call *call,
                                         void *rec,
                                         struct ring_buffer_event *event);
 
-extern int trace_define_field(struct ftrace_event_call *call, char *type,
-                              char *name, int offset, int size, int is_signed);
+extern int trace_define_field(struct ftrace_event_call *call,
+                              const char *type, const char *name,
+                              int offset, int size, int is_signed);
 extern int trace_define_common_fields(struct ftrace_event_call *call);
 
 #define is_signed_type(type)    (((type)(-1)) < 0)
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 8d57f77794ee..f124c8995555 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -190,6 +190,7 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
                 .event                  = &event_syscall_enter,         \
                 .raw_init               = init_enter_##sname,           \
                 .show_format            = syscall_enter_format,         \
+                .define_fields          = syscall_enter_define_fields,  \
                 .regfunc                = reg_event_syscall_enter,      \
                 .unregfunc              = unreg_event_syscall_enter,    \
                 .data                   = "sys"#sname,                  \
@@ -226,6 +227,7 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
                 .event                  = &event_syscall_exit,          \
                 .raw_init               = init_exit_##sname,            \
                 .show_format            = syscall_exit_format,          \
+                .define_fields          = syscall_exit_define_fields,   \
                 .regfunc                = reg_event_syscall_exit,       \
                 .unregfunc              = unreg_event_syscall_exit,     \
                 .data                   = "sys"#sname,                  \
@@ -233,6 +235,8 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
         }
 
 #define SYSCALL_METADATA(sname, nb)                             \
+        SYSCALL_TRACE_ENTER_EVENT(sname);                       \
+        SYSCALL_TRACE_EXIT_EVENT(sname);                        \
         static const struct syscall_metadata __used             \
           __attribute__((__aligned__(4)))                       \
           __attribute__((section("__syscalls_metadata")))       \
@@ -241,20 +245,22 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
                 .nb_args        = nb,                           \
                 .types          = types_##sname,                \
                 .args           = args_##sname,                 \
-        };                                                      \
-        SYSCALL_TRACE_ENTER_EVENT(sname);                       \
-        SYSCALL_TRACE_EXIT_EVENT(sname);
+                .enter_event    = &event_enter_##sname,         \
+                .exit_event     = &event_exit_##sname,          \
+        };
 
 #define SYSCALL_DEFINE0(sname)                                  \
+        SYSCALL_TRACE_ENTER_EVENT(_##sname);                    \
+        SYSCALL_TRACE_EXIT_EVENT(_##sname);                     \
         static const struct syscall_metadata __used             \
           __attribute__((__aligned__(4)))                       \
           __attribute__((section("__syscalls_metadata")))       \
           __syscall_meta_##sname = {                            \
                 .name           = "sys_"#sname,                 \
                 .nb_args        = 0,                            \
+                .enter_event    = &event_enter__##sname,        \
+                .exit_event     = &event_exit__##sname,         \
         };                                                      \
-        SYSCALL_TRACE_ENTER_EVENT(_##sname);                    \
-        SYSCALL_TRACE_EXIT_EVENT(_##sname);                     \
         asmlinkage long sys_##sname(void)
 #else
 #define SYSCALL_DEFINE0(name)      asmlinkage long sys_##name(void)
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 5ce85d75d31b..9661dd406b93 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -34,6 +34,8 @@ DECLARE_TRACE_WITH_CALLBACK(syscall_exit,
  * @args: list of args as strings (args[i] matches types[i])
  * @enter_id: associated ftrace enter event id
  * @exit_id: associated ftrace exit event id
+ * @enter_event: associated syscall_enter trace event
+ * @exit_event: associated syscall_exit trace event
  */
 struct syscall_metadata {
         const char      *name;
@@ -42,6 +44,9 @@ struct syscall_metadata {
         const char      **args;
         int             enter_id;
         int             exit_id;
+
+        struct ftrace_event_call *enter_event;
+        struct ftrace_event_call *exit_event;
 };
 
 #ifdef CONFIG_FTRACE_SYSCALLS
@@ -59,6 +64,8 @@ extern int syscall_enter_format(struct ftrace_event_call *call,
                                 struct trace_seq *s);
 extern int syscall_exit_format(struct ftrace_event_call *call,
                                 struct trace_seq *s);
+extern int syscall_enter_define_fields(struct ftrace_event_call *call);
+extern int syscall_exit_define_fields(struct ftrace_event_call *call);
 enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags);
 enum print_line_t print_syscall_exit(struct trace_iterator *iter, int flags);
 #endif