From 31155bc03e35a8d2b2551bc2eea3da5791e1b776 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Thu, 18 Oct 2007 23:41:08 -0700 Subject: [PATCH] Linux Kernel Markers - Samples Module example showing how to use the Linux Kernel Markers. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mathieu Desnoyers Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/marker.h | 1 - samples/Kconfig | 5 ++ samples/Makefile | 3 + samples/markers/Makefile | 4 ++ samples/markers/marker-example.c | 54 ++++++++++++++++++ samples/markers/probe-example.c | 98 ++++++++++++++++++++++++++++++++ 6 files changed, 164 insertions(+), 1 deletion(-) create mode 100644 samples/Makefile create mode 100644 samples/markers/Makefile create mode 100644 samples/markers/marker-example.c create mode 100644 samples/markers/probe-example.c diff --git a/include/linux/marker.h b/include/linux/marker.h index 8038d89b835d..5f36cf946bcb 100644 --- a/include/linux/marker.h +++ b/include/linux/marker.h @@ -61,7 +61,6 @@ struct marker { __attribute__((section("__markers"), aligned(8))) = \ { __mstrtab_name_##name, __mstrtab_format_##name, \ 0, __mark_empty_function, NULL }; \ - asm volatile("" : : "i" (&__mark_##name)); \ __mark_check_format(format, ## args); \ if (unlikely(__mark_##name.state)) { \ preempt_disable(); \ diff --git a/samples/Kconfig b/samples/Kconfig index b46b4cf4382f..57bb2236952c 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -7,5 +7,10 @@ menuconfig SAMPLES if SAMPLES +config SAMPLE_MARKERS + tristate "Build markers examples -- loadable modules only" + depends on MARKERS && m + help + This build markers example modules. endif # SAMPLES diff --git a/samples/Makefile b/samples/Makefile new file mode 100644 index 000000000000..5a4f0b6bcbed --- /dev/null +++ b/samples/Makefile @@ -0,0 +1,3 @@ +# Makefile for Linux samples code + +obj-$(CONFIG_SAMPLES) += markers/ diff --git a/samples/markers/Makefile b/samples/markers/Makefile new file mode 100644 index 000000000000..6d7231265f0f --- /dev/null +++ b/samples/markers/Makefile @@ -0,0 +1,4 @@ +# builds the kprobes example kernel modules; +# then to use one (as root): insmod + +obj-$(CONFIG_SAMPLE_MARKERS) += probe-example.o marker-example.o diff --git a/samples/markers/marker-example.c b/samples/markers/marker-example.c new file mode 100644 index 000000000000..e787c6d16dd7 --- /dev/null +++ b/samples/markers/marker-example.c @@ -0,0 +1,54 @@ +/* marker-example.c + * + * Executes a marker when /proc/marker-example is opened. + * + * (C) Copyright 2007 Mathieu Desnoyers + * + * This file is released under the GPLv2. + * See the file COPYING for more details. + */ + +#include +#include +#include +#include + +struct proc_dir_entry *pentry_example; + +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("Marker example"); diff --git a/samples/markers/probe-example.c b/samples/markers/probe-example.c new file mode 100644 index 000000000000..238b2e384fc8 --- /dev/null +++ b/samples/markers/probe-example.c @@ -0,0 +1,98 @@ +/* probe-example.c + * + * Connects two functions to marker call sites. + * + * (C) Copyright 2007 Mathieu Desnoyers + * + * This file is released under the GPLv2. + * See the file COPYING for more details. + */ + +#include +#include +#include +#include +#include + +struct probe_data { + const char *name; + const char *format; + marker_probe_func *probe_func; +}; + +void probe_subsystem_event(const struct marker *mdata, void *private, + 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(KERN_DEBUG "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 marker *mdata, void *private, + 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(KERN_INFO "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"); -- 2.20.1