tracing/ftrace: add the boot tracer

Add the boot/initcall tracer.

It's primary purpose is to be able to trace the initcalls.

It is intended to be used with scripts/bootgraph.pl after some small
improvements.

Note that it is not active after its init. To avoid tracing (and so
crashing) before the whole tracing engine init, you have to explicitly
call start_boot_trace() after do_pre_smp_initcalls() to enable it.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 5de9903645d5..91954eb6460f 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -5,6 +5,8 @@
 
 #include <linux/linkage.h>
 #include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/types.h>
 
 extern int ftrace_enabled;
 extern int
@@ -209,4 +211,21 @@ ftrace_init_module(unsigned long *start, unsigned long *end) { }
 #endif
 
 
+struct boot_trace {
+        pid_t                   caller;
+        initcall_t              func;
+        int                     result;
+        unsigned long long      duration;
+};
+
+#ifdef CONFIG_BOOT_TRACER
+extern void trace_boot(struct boot_trace *it);
+extern void start_boot_trace(void);
+#else
+static inline void trace_boot(struct boot_trace *it) { }
+static inline void start_boot_trace(void) { }
+#endif
+
+
+
 #endif /* _LINUX_FTRACE_H */