tracing/syscalls: core infrastructure for syscalls tracing, enhancements

Impact: new feature

This adds the generic support for syscalls tracing. This is
currently exploited through a devoted tracer but other tracing
engines can use it. (They just have to play with
{start,stop}_ftrace_syscalls() and use the display callbacks
unless they want to override them.)

The syscalls prototypes definitions are abused here to steal
some metadata informations:

- syscall name, param types, param names, number of params

The syscall addr is not directly saved during this definition
because we don't know if its prototype is available in the
namespace. But we don't really need it. The arch has just to
build a function able to resolve the syscall number to its
metadata struct.

The current tracer prints the syscall names, parameters names
and values (and their types optionally). Currently the value is
a raw hex but higher level values diplaying is on my TODO list.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1236955332-10133-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 17 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3d49daae47dc..d80ca0d464d9 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -194,6 +194,19 @@ struct kmemtrace_free_entry {
 	const void *ptr;
 };
 
+struct syscall_trace_enter {
+	struct trace_entry	ent;
+	int			nr;
+	unsigned long		args[];
+};
+
+struct syscall_trace_exit {
+	struct trace_entry	ent;
+	int			nr;
+	unsigned long		ret;
+};
+
+
 /*
  * trace_flag_type is an enumeration that holds different
  * states when a trace occurs. These are:
@@ -306,6 +319,10 @@ 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);				\
 		__ftrace_bad_type();					\
 	} while (0)