tracing: Add syscall tracepoints

add two tracepoints in syscall exit and entry path, conditioned on
TIF_SYSCALL_FTRACE. Supports the syscall trace event code.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

include/trace/syscall.h

@@ -1,8 +1,28 @@
 #ifndef _TRACE_SYSCALL_H
 #define _TRACE_SYSCALL_H
 
+#include <linux/tracepoint.h>
+
 #include <asm/ptrace.h>
 
+
+extern void syscall_regfunc(void);
+extern void syscall_unregfunc(void);
+
+DECLARE_TRACE_WITH_CALLBACK(syscall_enter,
+	TP_PROTO(struct pt_regs *regs, long id),
+	TP_ARGS(regs, id),
+	syscall_regfunc,
+	syscall_unregfunc
+);
+
+DECLARE_TRACE_WITH_CALLBACK(syscall_exit,
+	TP_PROTO(struct pt_regs *regs, long ret),
+	TP_ARGS(regs, ret),
+	syscall_regfunc,
+	syscall_unregfunc
+);
+
 /*
  * A syscall entry in the ftrace syscalls array.
  *