From 804defea1c020d5c52985685e56986f1a399acde Mon Sep 17 00:00:00 2001 From: Ananth N Mavinakayanahalli Date: Tue, 4 Mar 2008 14:28:38 -0800 Subject: Kprobes: move kprobe examples to samples/ Move kprobes examples from Documentation/kprobes.txt to under samples/. Patch originally by Randy Dunlap. o Updated the patch to apply on 2.6.25-rc3 o Modified examples code to build on multiple architectures. Currently, the kprobe and jprobe examples code works for x86 and powerpc o Cleaned up unneeded #includes o Cleaned up Kconfig per Sam Ravnborg's suggestions to fix build break on archs that don't have kretprobes o Implemented suggestions by Mathieu Desnoyers on CONFIG_KRETPROBES o Included Andrew Morton's cleanup based on x86-git o Modified kretprobe_example to act as a arch-agnostic module to determine routine execution times: Use 'modprobe kretprobe_example func=' to determine execution time of func_name in nanoseconds. Signed-off-by: Randy Dunlap Signed-off-by: Ananth N Mavinakayanahalli Acked-by: Mathieu Desnoyers Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- samples/kprobes/jprobe_example.c | 68 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 samples/kprobes/jprobe_example.c (limited to 'samples/kprobes/jprobe_example.c') diff --git a/samples/kprobes/jprobe_example.c b/samples/kprobes/jprobe_example.c new file mode 100644 index 000000000000..b7541355b92b --- /dev/null +++ b/samples/kprobes/jprobe_example.c @@ -0,0 +1,68 @@ +/* + * Here's a sample kernel module showing the use of jprobes to dump + * the arguments of do_fork(). + * + * For more information on theory of operation of jprobes, see + * Documentation/kprobes.txt + * + * Build and insert the kernel module as done in the kprobe example. + * You will see the trace data in /var/log/messages and on the + * console whenever do_fork() is invoked to create a new process. + * (Some messages may be suppressed if syslogd is configured to + * eliminate duplicate messages.) + */ + +#include +#include +#include + +/* + * Jumper probe for do_fork. + * Mirror principle enables access to arguments of the probed routine + * from the probe handler. + */ + +/* Proxy routine having the same arguments as actual do_fork() routine */ +static long jdo_fork(unsigned long clone_flags, unsigned long stack_start, + struct pt_regs *regs, unsigned long stack_size, + int __user *parent_tidptr, int __user *child_tidptr) +{ + printk(KERN_INFO "jprobe: clone_flags = 0x%lx, stack_size = 0x%lx," + " regs = 0x%p\n", + clone_flags, stack_size, regs); + + /* Always end with a call to jprobe_return(). */ + jprobe_return(); + return 0; +} + +static struct jprobe my_jprobe = { + .entry = jdo_fork, + .kp = { + .symbol_name = "do_fork", + }, +}; + +static int __init jprobe_init(void) +{ + int ret; + + ret = register_jprobe(&my_jprobe); + if (ret < 0) { + printk(KERN_INFO "register_jprobe failed, returned %d\n", ret); + return -1; + } + printk(KERN_INFO "Planted jprobe at %p, handler addr %p\n", + my_jprobe.kp.addr, my_jprobe.entry); + return 0; +} + +static void __exit jprobe_exit(void) +{ + unregister_jprobe(&my_jprobe); + printk(KERN_INFO "jprobe at %p unregistered\n", my_jprobe.kp.addr); +} + +module_init(jprobe_init) +module_exit(jprobe_exit) +MODULE_LICENSE("GPL"); -- cgit