[PATCH] [RFC] tracehook: Hook in syscall tracing markers.

[Paul Mundt <lethal@linux-sh.org>]

At kernel summit, the idea that syscall tracing was generally desirable
for tracing was mentioned several times, as was the argument that kernel
developers aren't placing markers in meaningful locations. This is a
simple patch to try and do that for the syscall case.

Presently LTTng attempts to litter these trace markers all over the
architecture code, primarily to get around the fact that there was no
generic way to get at this information before. Now that platforms are
starting to do their syscall entry/exit notifiers through tracehook and
we have the asm/syscall.h interface, all of this information can be
generically abstracted.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

---

 include/linux/tracehook.h |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 6186a78..481ff45 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -49,6 +49,9 @@
 #include <linux/sched.h>
 #include <linux/ptrace.h>
 #include <linux/security.h>
+#include <linux/marker.h>
+#include <asm/syscall.h>
+
 struct linux_binprm;
 
 /**
@@ -112,6 +115,8 @@ static inline __must_check int tracehook_report_syscall_entry(
 	struct pt_regs *regs)
 {
 	ptrace_report_syscall(regs);
+	trace_mark(kernel_arch_syscall_entry, "syscall_id %ld ip #p%ld",
+		   syscall_get_nr(NULL, regs), instruction_pointer(regs));
 	return 0;
 }
 
@@ -135,6 +140,8 @@ static inline __must_check int tracehook_report_syscall_entry(
 static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)
 {
 	ptrace_report_syscall(regs);
+	trace_mark(kernel_arch_syscall_exit, "ret %ld",
+		   syscall_get_return_value(NULL, regs));
 }
 
 /**