[PATCH] Linux Kernel Markers

Mathieu Desnoyers
2006-09-18T23:45:07Z

Hello,

Following this huge discussion thread, I tried to come with a marker mechanism
(which is something everyone seems to agree that is a necessity) that would be
useful to each kind of tracing (dynamic and static) (concerned projects :
SystemTAP, LKET, LKST, LTTng) and even combinations of those. Religious
considerations aside, I really think that this kind of generic markup is
necessary to fill *everybody*'s need. If I forgot about a specific genericity
aspect, please tell me.

I take for agreed that both static and dynamic tracing are useful for different
needs and that a full markup must support both and combinations, letting the
user or the distribution choose.

If you like it, please add the right menuconfig lines in arch/*/Kconfig and a
NOPS macro in include/asm-*/marker.h.

Comments are, as always, welcome.

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@polymtl.ca>
+ *
+ * September 2006
+ */
+
+#define JPROBE_TARGET \
+ __asm__ ( GENERIC_NOP5 )
--- /dev/null
+++ b/include/linux/marker.h
@@ -0,0 +1,77 @@
+/*****************************************************************************
+ * 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, "Event happened %d %s", someint, somestring);
+ * Where :
+ * - Subsystem is the name of your subsystem.
+ * - event is the name of the event to mark.
+ * - "Event happened %d %s" is the formatted string for printk.
+ * - someint is an integer.
+ * - somestring is a char *.
+ *
+ * Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ *
+ * September 2006
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+
+#include <asm/marker.h>
+
+#define MARK_SYM(event) \
+ __asm__ ( "__mark_" KBUILD_BASENAME "_" #event ":" )
+
+#define MARK_INACTIVE(event, format, args...)
+
+#define MARK_PRINT(event, format, args...) printk(format, ##args);
+
+#define MARK_FPROBE(event, format, args...) fprobe_##event(args);
+
+#define MARK_KPROBE(event, format, args...) MARK_SYM(event);
+
+#define MARK_JPROBE(event, format, args...) \
+ do { \
+ 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
+
+
--- /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 y
+ help
+ Activate markers that cannot be instrumented dynamically. They will
+ generate function calls to each function-style probe.
+
+endmenu

--- END ---

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