tracing/syscalls: Add fields format for exit events

Add "format" file for syscall exit events:

 # cat events/syscalls/sys_exit_open/format
 name: sys_exit_open
 ID: 344
 format:
         field:unsigned short common_type;       offset:0;       size:2;
         field:unsigned char common_flags;       offset:2;       size:1;
         field:unsigned char common_preempt_count;       offset:3;       size:1;
         field:int common_pid;   offset:4;       size:4;
         field:int common_tgid;  offset:8;       size:4;

         field:int nr;   offset:12;      size:4;
         field:unsigned long ret;        offset:16;      size:4;

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: <4A8BAF61.3060307@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/syscalls.h

@@ -189,7 +189,7 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
 		.system                 = "syscalls",			\
 		.event                  = &event_syscall_enter,		\
 		.raw_init		= init_enter_##sname,		\
-		.show_format		= ftrace_format_syscall,	\
+		.show_format		= syscall_enter_format,		\
 		.regfunc		= reg_event_syscall_enter,	\
 		.unregfunc		= unreg_event_syscall_enter,	\
 		.data			= "sys"#sname,			\
@@ -225,6 +225,7 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
 		.system                 = "syscalls",			\
 		.event                  = &event_syscall_exit,		\
 		.raw_init		= init_exit_##sname,		\
+		.show_format		= syscall_exit_format,		\
 		.regfunc		= reg_event_syscall_exit,	\
 		.unregfunc		= unreg_event_syscall_exit,	\
 		.data			= "sys"#sname,			\

include/trace/syscall.h

@@ -55,8 +55,10 @@ extern int reg_event_syscall_enter(void *ptr);
 extern void unreg_event_syscall_enter(void *ptr);
 extern int reg_event_syscall_exit(void *ptr);
 extern void unreg_event_syscall_exit(void *ptr);
-extern int
-ftrace_format_syscall(struct ftrace_event_call *call, struct trace_seq *s);
+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);
 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

kernel/trace/trace_syscalls.c

@@ -97,7 +97,7 @@ extern char *__bad_type_size(void);
 		__bad_type_size() :					\
 		#type, #name, offsetof(typeof(trace), name), sizeof(trace.name)
 
-int ftrace_format_syscall(struct ftrace_event_call *call, struct trace_seq *s)
+int syscall_enter_format(struct ftrace_event_call *call, struct trace_seq *s)
 {
 	int i;
 	int nr;
@@ -149,6 +149,22 @@ int ftrace_format_syscall(struct ftrace_event_call *call, struct trace_seq *s)
 	return ret;
 }
 
+int syscall_exit_format(struct ftrace_event_call *call, struct trace_seq *s)
+{
+	int ret;
+	struct syscall_trace_exit trace;
+
+	ret = trace_seq_printf(s,
+			       "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
+			       "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n",
+			       SYSCALL_FIELD(int, nr),
+			       SYSCALL_FIELD(unsigned long, ret));
+	if (!ret)
+		return 0;
+
+	return trace_seq_printf(s, "\nprint fmt: \"0x%%lx\", REC->ret\n");
+}
+
 void ftrace_syscall_enter(struct pt_regs *regs, long id)
 {
 	struct syscall_trace_enter *entry;