Linux Kernel Markers

Index: linux-2.6-lttng/arch/alpha/Kconfig
===================================================================
@@ -646,6 +646,8 @@ config SRM_ENV
 
 source "fs/Kconfig.binfmt"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "net/Kconfig"

Index: linux-2.6-lttng/arch/arm/Kconfig
===================================================================
@@ -1054,6 +1054,8 @@ source "drivers/rtc/Kconfig"
 
 source "drivers/dma/Kconfig"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "fs/Kconfig"

Index: linux-2.6-lttng/arch/cris/Kconfig
===================================================================
@@ -151,6 +151,8 @@ source "net/Kconfig"
 menu "Drivers for built-in interfaces"
 source arch/cris/arch-v10/drivers/Kconfig
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "drivers/base/Kconfig"

Index: linux-2.6-lttng/arch/frv/Kconfig
===================================================================
@@ -367,6 +367,8 @@ menu "Executable formats"
 
 source "fs/Kconfig.binfmt"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "net/Kconfig"

Index: linux-2.6-lttng/arch/h8300/Kconfig
===================================================================
@@ -219,6 +219,8 @@ source "drivers/hwmon/Kconfig"
 
 source "drivers/usb/Kconfig"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "fs/Kconfig"

Index: linux-2.6-lttng/arch/i386/Kconfig
===================================================================
@@ -1263,6 +1263,8 @@ config KPROBES
 	  for kernel debugging, non-intrusive instrumentation and testing.
 	  If in doubt, say "N".
 
+source "kernel/Kconfig.marker"
+
 endif # INSTRUMENTATION
 
 source "arch/i386/Kconfig.debug"

Index: linux-2.6-lttng/arch/ia64/Kconfig
===================================================================
@@ -536,6 +536,8 @@ source "drivers/pci/hotplug/Kconfig"
 
 source "drivers/pcmcia/Kconfig"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 endif

Index: linux-2.6-lttng/arch/m32r/Kconfig
===================================================================
@@ -418,6 +418,8 @@ menu "Executable file formats"
 
 source "fs/Kconfig.binfmt"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "net/Kconfig"

Index: linux-2.6-lttng/arch/m68k/Kconfig
===================================================================
@@ -679,6 +679,8 @@ config SERIAL_CONSOLE
 
 	  If unsure, say N.
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "fs/Kconfig"

Index: linux-2.6-lttng/arch/m68knommu/Kconfig
===================================================================
@@ -673,6 +673,8 @@ source "drivers/pcmcia/Kconfig"
 
 source "drivers/pci/hotplug/Kconfig"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 menu "Executable file formats"

Index: linux-2.6-lttng/arch/mips/Kconfig
===================================================================
@@ -1925,6 +1925,8 @@ menu "Power management options"
 
 source "kernel/power/Kconfig"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "net/Kconfig"

Index: linux-2.6-lttng/arch/parisc/Kconfig
===================================================================
@@ -259,6 +259,8 @@ menu "Executable file formats"
 
 source "fs/Kconfig.binfmt"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "net/Kconfig"

Index: linux-2.6-lttng/arch/powerpc/Kconfig
===================================================================
@@ -495,6 +495,8 @@ source "drivers/pcmcia/Kconfig"
 
 source "drivers/pci/hotplug/Kconfig"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 menu "Advanced setup"

Index: linux-2.6-lttng/arch/ppc/Kconfig
===================================================================
@@ -1449,6 +1449,8 @@ config SERIAL_SICC_CONSOLE
 	depends on SERIAL_SICC && UART0_TTYS1
 	default y
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "lib/Kconfig"

Index: linux-2.6-lttng/arch/s390/Kconfig
===================================================================
@@ -543,6 +543,8 @@ config KPROBES
 	  for kernel debugging, non-intrusive instrumentation and testing.
 	  If in doubt, say "N".
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "arch/s390/Kconfig.debug"

Index: linux-2.6-lttng/arch/sh/Kconfig
===================================================================
@@ -723,6 +723,8 @@ depends on EXPERIMENTAL && SYS_SUPPORTS_
 
 source kernel/power/Kconfig
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "net/Kconfig"

Index: linux-2.6-lttng/arch/sh64/Kconfig
===================================================================
@@ -277,6 +277,8 @@ menu "Executable file formats"
 
 source "fs/Kconfig.binfmt"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "net/Kconfig"

Index: linux-2.6-lttng/arch/sparc/Kconfig
===================================================================
@@ -316,6 +316,8 @@ config UNIX98_PTY_COUNT
 	  When not in use, each additional set of 256 PTYs occupy
 	  approximately 8 KB of kernel memory on 32-bit architectures.
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "fs/Kconfig"

Index: linux-2.6-lttng/arch/sparc64/Kconfig
===================================================================
@@ -412,6 +412,8 @@ config SOLARIS_EMUL
 	  To compile this code as a module, choose M here: the
 	  module will be called solaris.
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 config SCHED_SMT

Index: linux-2.6-lttng/arch/um/Kconfig
===================================================================
@@ -253,6 +253,8 @@ config UML_REAL_TIME_CLOCK
 	  This could result in a noticeable lag.  If this is a problem, then
 	  disable this option.
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "init/Kconfig"

Index: linux-2.6-lttng/arch/v850/Kconfig
===================================================================
@@ -294,6 +294,8 @@ source "drivers/ide/Kconfig"
 
 source "drivers/scsi/Kconfig"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 #############################################################################

Index: linux-2.6-lttng/arch/x86_64/Kconfig
===================================================================
@@ -810,6 +810,8 @@ config SYSVIPC_COMPAT
 	depends on COMPAT && SYSVIPC
 	default y
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "net/Kconfig"

Index: linux-2.6-lttng/arch/xtensa/Kconfig
===================================================================
@@ -226,6 +226,8 @@ config KCORE_ELF
 
 source "fs/Kconfig.binfmt"
 
+source "kernel/Kconfig.marker"
+
 endmenu
 
 source "net/Kconfig"

Index: linux-2.6-lttng/kernel/Kconfig.marker
===================================================================
@@ -0,0 +1,7 @@
+# Code markers configuration
+
+config MARKERS
+	bool "Activate markers"
+	help
+	  Place an empty function call at each marker site. Can be
+	  dynamically changed for a probe function.

Index: linux-2.6-lttng/arch/avr32/Kconfig.debug
===================================================================
@@ -6,6 +6,9 @@ config TRACE_IRQFLAGS_SUPPORT
 
 source "lib/Kconfig.debug"
 
+menu "Instrumentation Support"
+	depends on EXPERIMENTAL
+
 config KPROBES
 	bool "Kprobes"
 	depends on DEBUG_KERNEL

@@ -16,4 +19,8 @@ config KPROBES
           for kernel debugging, non-intrusive instrumentation and testing.
           If in doubt, say "N".
 
+source "kernel/Kconfig.marker"
+
+endmenu
+
 endmenu

Index: linux-2.6-lttng/kernel/Makefile
===================================================================
@@ -60,6 +60,7 @@ obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
 obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
 obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
 obj-$(CONFIG_IMMEDIATE) += immediate.o
+obj-$(CONFIG_MARKERS) += marker.o
 
 ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <[email protected]>, the -fno-omit-frame-pointer is

Index: linux-2.6-lttng/Documentation/marker.txt
===================================================================
@@ -0,0 +1,257 @@
+ 	             Using the Linux Kernel Markers
+
+			    Mathieu Desnoyers
+
+
+This document introduces Linux Kernel Markers and their use. It provides
+examples of how to insert markers in the kernel and connect probe functions to
+them and provides some examples of probe functions.
+
+
+* Purpose of markers
+
+A marker placed in your code provides a hook to call a function (probe) that
+you can provide at runtime. A marker can be "on" (a probe is connected to it) or
+"off" (no probe is attached). When a marker is "off" it has no effect, except
+for adding a tiny time penality (checking a condition for a branch) and space
+penality (adding a few bytes for the function call at the end of the
+instrumented function and adds a data structure in a separate section). The
+immediate values are used to minimize the impact on data cache, encoding the
+condition in the instruction stream. When a marker is "on", the function you
+provide is called each time the marker is executed, in the execution context of
+the caller. When the function provided ends its execution, it returns to the
+caller (continuing from the marker site).
+
+You can put markers at important locations in the code. Markers are
+lightweight hooks that can pass an arbitrary number of parameters,
+described in a printk-like format string, to the attached probe function.
+
+They can be used for tracing and performance accounting.
+
+
+* Usage
+
+In order to use the macro trace_mark, you should include linux/marker.h.
+
+#include <linux/marker.h>
+
+Add, in your code :
+
+trace_mark(subsystem_event, "%d %s", someint, somestring);
+Where :
+- subsystem_event is an identifier unique to your event
+    - subsystem is the name of your subsystem.
+    - event is the name of the event to mark.
+- "%d %s" is the formatted string for the serializer.
+- someint is an integer.
+- somestring is a char pointer.
+
+Connecting a function (probe) to a marker is done by providing a probe (function
+to call) for the specific marker through marker_probe_register() and can be
+activated by calling marker_arm(). Marker deactivation can be done by calling
+marker_disarm() as many times as marker_arm() has been called. Removing a probe
+is done through marker_probe_unregister(); it will disarm the probe and make
+sure there is no caller left using the probe when it returns. Probe removal is
+preempt-safe because preemption is disabled around the probe call. See the
+"Probe example" section below for a sample probe module.
+
+The marker mechanism supports inserting multiple instances of the same marker.
+Markers can be put in inline functions, inlined static functions, and
+unrolled loops.
+
+The naming scheme "subsystem_event" is suggested here as a convention intended
+to limit collisions. Marker names are global to the kernel: they are considered
+as being the same whether they are in the core kernel image or in modules.
+Conflicting format strings for markers with the same name will cause the markers
+to be detected to have a different format string not to be armed and will output
+a printk warning which identifies the inconsistency:
+
+"Format mismatch for probe probe_name (format), marker (format)"
+
+
+* Optimization for a given architecture
+
+One can implement optimized markers for a given architecture by replacing
+asm-$ARCH/marker.h.
+
+To force use of a non-optimized version of the markers, _trace_mark() should be
+used. It takes the same parameters as the normal markers, but it does not use
+the immediate values based on code patching.
+
+
+* Probe example
+
+You can build the kernel modules, probe-example.ko and marker-example.ko,
+using the following Makefile:
+------------------------------ CUT -------------------------------------
+obj-m := probe-example.o marker-example.o
+KDIR := /lib/modules/$(shell uname -r)/build
+PWD := $(shell pwd)
+default:
+	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
+clean:
+	rm -f *.mod.c *.ko *.o
+------------------------------ CUT -------------------------------------
+/* probe-example.c
+ *
+ * Connects two functions to marker call sites.
+ *
+ * (C) Copyright 2007 Mathieu Desnoyers <[email protected]>
+ *
+ * This file is released under the GPLv2.
+ * See the file COPYING for more details.
+ */
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/marker.h>
+#include <asm/atomic.h>
+
+struct probe_data {
+	const char *name;
+	const char *format;
+	marker_probe_func *probe_func;
+};
+
+void probe_subsystem_event(const struct __mark_marker *mdata,
+		const char *format, ...)
+{
+	va_list ap;
+	/* Declare args */
+	unsigned int value;
+	const char *mystr;
+
+	/* Assign args */
+	va_start(ap, format);
+	value = va_arg(ap, typeof(value));
+	mystr = va_arg(ap, typeof(mystr));
+
+	/* Call printk */
+	printk("Value %u, string %s\n", value, mystr);
+
+	/* or count, check rights, serialize data in a buffer */
+
+	va_end(ap);
+}
+
+atomic_t eventb_count = ATOMIC_INIT(0);
+
+void probe_subsystem_eventb(const struct __mark_marker *mdata,
+	const char *format, ...)
+{
+	/* Increment counter */
+	atomic_inc(&eventb_count);
+}
+
+static struct probe_data probe_array[] =
+{
+	{	.name = "subsystem_event",
+		.format = "%d %s",
+		.probe_func = probe_subsystem_event },
+	{	.name = "subsystem_eventb",
+		.format = MARK_NOARGS,
+		.probe_func = probe_subsystem_eventb },
+};
+
+static int __init probe_init(void)
+{
+	int result;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(probe_array); i++) {
+		result = marker_probe_register(probe_array[i].name,
+				probe_array[i].format,
+				probe_array[i].probe_func, &probe_array[i]);
+		if (result)
+			printk(KERN_INFO "Unable to register probe %s\n",
+				probe_array[i].name);
+		result = marker_arm(probe_array[i].name);
+		if (result)
+			printk(KERN_INFO "Unable to arm probe %s\n",
+				probe_array[i].name);
+	}
+	return 0;
+}
+
+static void __exit probe_fini(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(probe_array); i++) {
+		marker_probe_unregister(probe_array[i].name);
+	}
+	printk("Number of event b : %u\n", atomic_read(&eventb_count));
+}
+
+module_init(probe_init);
+module_exit(probe_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("SUBSYSTEM Probe");
+------------------------------ CUT -------------------------------------
+/* marker-example.c
+ *
+ * Executes a marker when /proc/marker-example is opened.
+ *
+ * (C) Copyright 2007 Mathieu Desnoyers <[email protected]>
+ *
+ * This file is released under the GPLv2.
+ * See the file COPYING for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/marker.h>
+#include <linux/sched.h>
+#include <linux/proc_fs.h>
+
+struct proc_dir_entry *pentry_example = NULL;
+
+static int my_open(struct inode *inode, struct file *file)
+{
+	int i;
+
+	trace_mark(subsystem_event, "%d %s", 123, "example string");
+	for (i=0; i<10; i++) {
+		trace_mark(subsystem_eventb, MARK_NOARGS);
+	}
+	return -EPERM;
+}
+
+static struct file_operations mark_ops = {
+	.open = my_open,
+};
+
+static int example_init(void)
+{
+	printk(KERN_ALERT "example init\n");
+	pentry_example = create_proc_entry("marker-example", 0444, NULL);
+	if (pentry_example)
+		pentry_example->proc_fops = &mark_ops;
+	else
+		return -EPERM;
+	return 0;
+}
+
+static void example_exit(void)
+{
+	printk(KERN_ALERT "example exit\n");
+	remove_proc_entry("marker-example", NULL);
+}
+
+module_init(example_init)
+module_exit(example_exit)
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit example");
+------------------------------ CUT -------------------------------------
+Sequence of operations : (as root)
+make
+insmod marker-example.ko (insmod order is not important)
+insmod probe-example.ko
+cat /proc/marker-example (returns an expected error)
+rmmod marker-example probe-example
+dmesg
+------------------------------ CUT -------------------------------------

Index: linux-2.6-lttng/block/Kconfig
===================================================================
@@ -32,6 +32,7 @@ config BLK_DEV_IO_TRACE
 	depends on SYSFS
 	select RELAY
 	select DEBUG_FS
+	select MARKERS
 	help
 	  Say Y here, if you want to be able to trace the block layer actions
 	  on a given queue. Tracing allows you to see any traffic happening

Index: linux-2.6/arch/powerpc/platforms/cell/spufs/Makefile
===================================================================
@@ -4,6 +4,8 @@ obj-$(CONFIG_SPU_FS) += spufs.o
 spufs-y += inode.o file.o context.o syscalls.o coredump.o
 spufs-y += sched.o backing_ops.o hw_ops.o run.o gang.o
 
+obj-m += sputrace.o
+
 # Rules to build switch.o with the help of SPU tool chain
 SPU_CROSS	:= spu-
 SPU_CC		:= $(SPU_CROSS)gcc