[PATCH 09/12] add support traceopint ids

[Jason Baron <jbaron@redhat.com>]

This patch associates an id with each syscall trace event, so that we can
identify each syscall trace event using the 'perf' tool.

Signed-off-by: Jason Baron <jbaron@redhat.com>

---
 arch/x86/kernel/ftrace.c      |   10 ++++++++++
 include/linux/syscalls.h      |   22 ++++++++++++++++++----
 include/trace/syscall.h       |    8 ++++++++
 kernel/trace/trace.h          |    6 ------
 kernel/trace/trace_syscalls.c |   26 ++++++++++++++++----------
 5 files changed, 52 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 0d93d40..3cff121 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -516,6 +516,16 @@ int syscall_name_to_nr(char *name)
 	return -1;
 }
 
+void set_syscall_enter_id(int num, int id)
+{
+	syscalls_metadata[num]->enter_id = id;
+}
+
+void set_syscall_exit_id(int num, int id)
+{
+	syscalls_metadata[num]->exit_id = id;
+}
+
 static int __init arch_init_ftrace_syscalls(void)
 {
 	int i;
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 5e5b4d3..ce4b01c 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -116,13 +116,20 @@ struct perf_counter_attr;
 
 #define SYSCALL_TRACE_ENTER_EVENT(sname)				\
 	static struct ftrace_event_call event_enter_##sname;		\
+	struct trace_event enter_syscall_print_##sname = {		\
+		.trace                  = print_syscall_enter,		\
+	};								\
 	static int init_enter_##sname(void)				\
 	{								\
-		int num;						\
+		int num, id;						\
 		num = syscall_name_to_nr("sys"#sname);			\
 		if (num < 0)						\
 			return -ENOSYS;					\
-		register_ftrace_event(&event_syscall_enter);		\
+		id = register_ftrace_event(&enter_syscall_print_##sname);\
+		if (!id)						\
+			return -ENODEV;					\
+		event_enter_##sname.id = id;				\
+		set_syscall_enter_id(num, id);				\
 		INIT_LIST_HEAD(&event_enter_##sname.fields);		\
 		init_preds(&event_enter_##sname);			\
 		return 0;						\
@@ -142,13 +149,20 @@ struct perf_counter_attr;
 
 #define SYSCALL_TRACE_EXIT_EVENT(sname)					\
 	static struct ftrace_event_call event_exit_##sname;		\
+	struct trace_event exit_syscall_print_##sname = {		\
+		.trace                  = print_syscall_exit,		\
+	};								\
 	static int init_exit_##sname(void)				\
 	{								\
-		int num;						\
+		int num, id;						\
 		num = syscall_name_to_nr("sys"#sname);			\
 		if (num < 0)						\
 			return -ENOSYS;					\
-		register_ftrace_event(&event_syscall_exit);		\
+		id = register_ftrace_event(&exit_syscall_print_##sname);\
+		if (!id)						\
+			return -ENODEV;					\
+		event_exit_##sname.id = id;				\
+		set_syscall_exit_id(num, id);				\
 		INIT_LIST_HEAD(&event_exit_##sname.fields);		\
 		init_preds(&event_exit_##sname);			\
 		return 0;						\
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 73fb8b4..df62840 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -32,23 +32,31 @@ DECLARE_TRACE_WITH_CALLBACK(syscall_exit,
  * @nb_args: number of parameters it takes
  * @types: list of types as strings
  * @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
  */
 struct syscall_metadata {
 	const char	*name;
 	int		nb_args;
 	const char	**types;
 	const char	**args;
+	int		enter_id;
+	int		exit_id;
 };
 
 #ifdef CONFIG_FTRACE_SYSCALLS
 extern struct syscall_metadata *syscall_nr_to_meta(int nr);
 extern int syscall_name_to_nr(char *name);
+void set_syscall_enter_id(int num, int id);
+void set_syscall_exit_id(int num, int id);
 extern struct trace_event event_syscall_enter;
 extern struct trace_event event_syscall_exit;
 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);
+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
 
 #endif /* _TRACE_SYSCALL_H */
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 44308f3..606073c 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -38,8 +38,6 @@ enum trace_type {
 	TRACE_GRAPH_ENT,
 	TRACE_USER_STACK,
 	TRACE_HW_BRANCHES,
-	TRACE_SYSCALL_ENTER,
-	TRACE_SYSCALL_EXIT,
 	TRACE_KMEM_ALLOC,
 	TRACE_KMEM_FREE,
 	TRACE_POWER,
@@ -334,10 +332,6 @@ extern void __ftrace_bad_type(void);
 			  TRACE_KMEM_ALLOC);	\
 		IF_ASSIGN(var, ent, struct kmemtrace_free_entry,	\
 			  TRACE_KMEM_FREE);	\
-		IF_ASSIGN(var, ent, struct syscall_trace_enter,		\
-			  TRACE_SYSCALL_ENTER);				\
-		IF_ASSIGN(var, ent, struct syscall_trace_exit,		\
-			  TRACE_SYSCALL_EXIT);				\
 		IF_ASSIGN(var, ent, struct ksym_trace_entry, TRACE_KSYM);\
 		__ftrace_bad_type();					\
 	} while (0)
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index c7ae25e..e58a9c1 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -36,14 +36,18 @@ print_syscall_enter(struct trace_iterator *iter, int flags)
 	struct syscall_metadata *entry;
 	int i, ret, syscall;
 
-	trace_assign_type(trace, ent);
-
+	trace = (typeof(trace))ent;
 	syscall = trace->nr;
-
 	entry = syscall_nr_to_meta(syscall);
+
 	if (!entry)
 		goto end;
 
+	if (entry->enter_id != ent->type) {
+		WARN_ON_ONCE(1);
+		goto end;
+	}
+
 	ret = trace_seq_printf(s, "%s(", entry->name);
 	if (!ret)
 		return TRACE_TYPE_PARTIAL_LINE;
@@ -78,16 +82,20 @@ print_syscall_exit(struct trace_iterator *iter, int flags)
 	struct syscall_metadata *entry;
 	int ret;
 
-	trace_assign_type(trace, ent);
-
+	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_id != 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)
@@ -114,7 +122,7 @@ void ftrace_syscall_enter(struct pt_regs *regs, long id)
 
 	size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
 
-	event = trace_current_buffer_lock_reserve(TRACE_SYSCALL_ENTER, size,
+	event = trace_current_buffer_lock_reserve(sys_data->enter_id, size,
 							0, 0);
 	if (!event)
 		return;
@@ -142,7 +150,7 @@ void ftrace_syscall_exit(struct pt_regs *regs, long ret)
 	if (!sys_data)
 		return;
 
-	event = trace_current_buffer_lock_reserve(TRACE_SYSCALL_EXIT,
+	event = trace_current_buffer_lock_reserve(sys_data->exit_id,
 				sizeof(*entry), 0, 0);
 	if (!event)
 		return;
@@ -239,10 +247,8 @@ void unreg_event_syscall_exit(void *ptr)
 
 struct trace_event event_syscall_enter = {
 	.trace			= print_syscall_enter,
-	.type			= TRACE_SYSCALL_ENTER
 };
 
 struct trace_event event_syscall_exit = {
 	.trace			= print_syscall_exit,
-	.type			= TRACE_SYSCALL_EXIT
 };
-- 
1.6.2.5