[PATCH] Linux Kernel Markers 0.2 for Linux 2.6.17

[Mathieu Desnoyers]

Good afternoon,

Following some very interesting ideas from Martin that shows that even
static function calls and inlined functions can be used in interesting
ways with markers to deploy dynamic tracers with easy access to local
function variables, I send this slightly improved version of Linux Kernel
Markers.

It has the same capabilities as the previous one and additionnaly checks
for string format consistency in every kernel configuration. The idea
behind this is to be told be the compiler as soon as a marker is broken.

These last emails convince me even more that a markup mechanism must
interface with every kind of instrumentation hooking we can think about,
both dynamic and static.

Mathieu

--- BEGIN ---

--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -1082,6 +1082,8 @@ config KPROBES
 	  for kernel debugging, non-intrusive instrumentation and testing.
 	  If in doubt, say "N".
 
+source "kernel/Kconfig.marker"
+
 source "ltt/Kconfig"
 
 endmenu
--- /dev/null
+++ b/include/asm-i386/marker.h
@@ -0,0 +1,12 @@
+/*****************************************************************************
+ * marker.h
+ *
+ * Code markup for dynamic and static tracing. i386 support.
+ *
+ * Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
+ *
+ * September 2006
+ */
+
+#define JPROBE_TARGET \
+	__asm__ ( GENERIC_NOP5 )
--- /dev/null
+++ b/include/linux/marker.h
@@ -0,0 +1,93 @@
+/*****************************************************************************
+ * marker.h
+ *
+ * Code markup for dynamic and static tracing.
+ *
+ * Use either :
+ * MARK
+ * MARK_NOPRINT (will never call printk)
+ * MARK_STATIC (not dynamically instrumentable, will never call printk)
+ *
+ * Example :
+ *
+ * MARK(subsystem_event, "%d %s", someint, somestring);
+ * Where :
+ * - Subsystem is the name of your subsystem.
+ * - event is the name of the event to mark.
+ * - "%d %s" is the formatted string for printk.
+ * - someint is an integer.
+ * - somestring is a char *.
+ * - subsystem_event must be unique thorough the kernel!
+ *
+ * Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
+ *
+ * September 2006
+ */
+
+#include <asm/marker.h>
+
+#define MARK_SYM(event) \
+	__asm__ ( "__mark_" #event ":" )
+
+#define MARK_INACTIVE(event, format, args...) \
+	__mark_check_format(format, ## args)
+
+#define MARK_PRINT(event, format, args...) \
+	do { \
+		__mark_check_format(format, ## args); \
+		printk(#event ": " format, ## args); \
+	} while(0)
+
+#define MARK_FPROBE(event, format, args...) \
+	do { \
+		__mark_check_format(format, ## args); \
+		fprobe_##event(args); \
+	} while(0)
+
+#define MARK_KPROBE(event, format, args...) \
+	do { \
+		__mark_check_format(format, ## args); \
+		MARK_SYM(event); \
+	} while(0)
+
+#define MARK_JPROBE(event, format, args...) \
+	do { \
+		__mark_check_format(format, ## args); \
+		MARK_SYM(event); \
+		JPROBE_TARGET; \
+	} while(0)
+
+/* Menu configured markers */
+#ifndef CONFIG_MARK
+#define MARK	MARK_INACTIVE
+#elif defined(CONFIG_MARK_PRINT)
+#define MARK	MARK_PRINT
+#elif defined(CONFIG_MARK_FPROBE)
+#define MARK	MARK_FPROBE
+#elif defined(CONFIG_MARK_KPROBE)
+#define MARK	MARK_KPROBE
+#elif defined(CONFIG_MARK_JPROBE)
+#define MARK	MARK_JPROBE
+#endif
+
+#ifndef CONFIG_MARK_NOPRINT
+#define MARK_NOPRINT	MARK_INACTIVE
+#elif defined(CONFIG_MARK_NOPRINT_FPROBE)
+#define MARK_NOPRINT	MARK_FPROBE
+#elif defined(CONFIG_MARK_NOPRINT_KPROBE)
+#define MARK_NOPRINT	MARK_KPROBE
+#elif defined(CONFIG_MARK_NOPRINT_JPROBE)
+#define MARK_NOPRINT	MARK_JPROBE
+#endif
+
+#ifndef CONFIG_MARK_STATIC
+#define MARK_STATIC	MARK_INACTIVE
+#else
+#define MARK_STATIC	MARK_FPROBE
+#endif
+
+static inline void __mark_check_format(const char *fmt, ...)
+	__attribute__ ((format (printf, 1, 2)));
+void __mark_check_format(const char *fmt, ...) {  }
+
+
--- /dev/null
+++ b/kernel/Kconfig.marker
@@ -0,0 +1,75 @@
+# Code markers configuration
+
+menu "Marker configuration"
+
+
+config MARK
+	bool "Enable MARK code markers"
+	default y
+	help
+	  Activate markers that can call printk or can be instrumented
+	  dynamically.
+
+choice
+	prompt "MARK code marker behavior"
+	default MARK_KPROBE
+	depends on MARK
+	help
+	  Configuration of markers that can call printk or can be
+	  instrumented dynamically.
+
+config MARK_KPROBE
+	bool "KPROBE"
+	---help---
+	Change markers for a symbol "__mark_modulename_event".
+config MARK_JPROBE
+	bool "JPROBE"
+	---help---
+	Change markers for a symbol "__mark_modulename_event"
+	and create a target for a high speed dynamic probe.
+config MARK_FPROBE
+	bool "FPROBE"
+	---help---
+	Change markers for a function call.
+config MARK_PRINT
+	bool "PRINT"
+	---help---
+	Call printk from the marker.
+endchoice
+
+config MARK_NOPRINT
+	bool "Enable MARK_NOPRINT code markers"
+	default y
+	help
+	  Activate markers that cannot call printk.
+ 
+choice
+	prompt "MARK_NOPRINT code marker behavior"
+	default MARK_NOPRINT_KPROBE
+	depends on MARK_NOPRINT
+	help
+	  Configuration of markers that cannot call printk.
+
+config MARK_NOPRINT_KPROBE
+	bool "KPROBE"
+	---help---
+	Change markers for a symbol "__mark_modulename_event".
+config MARK_NOPRINT_JPROBE
+	bool "JPROBE"
+	---help---
+	Change markers for a symbol "__mark_modulename_event"
+	and create a target for a high speed dynamic probe.
+config MARK_NOPRINT_FPROBE
+	bool "FPROBE"
+	---help---
+	Change markers for a function call.
+endchoice
+
+config MARK_STATIC
+	bool "Enable MARK_STATIC code markers"
+	default n
+	help
+	  Activate markers that cannot be instrumented dynamically. They will
+	  generate function calls to each function-style probe.
+
+endmenu

--- END ---

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