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authorAnanth N Mavinakayanahalli2008-03-04 16:28:38 -0600
committerLinus Torvalds2008-03-04 18:35:11 -0600
commit804defea1c020d5c52985685e56986f1a399acde (patch)
treedd91b81d272522ec8e5e482408734dd290fed152 /samples/kprobes
parent9edddaa200df18e08fe0cf21036e8ae467b1363c (diff)
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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=<func_name>' to determine execution time of func_name in nanoseconds. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'samples/kprobes')
-rw-r--r--samples/kprobes/Makefile5
-rw-r--r--samples/kprobes/jprobe_example.c68
-rw-r--r--samples/kprobes/kprobe_example.c91
-rw-r--r--samples/kprobes/kretprobe_example.c106
4 files changed, 270 insertions, 0 deletions
diff --git a/samples/kprobes/Makefile b/samples/kprobes/Makefile
new file mode 100644
index 00000000000..68739bc4fc6
--- /dev/null
+++ b/samples/kprobes/Makefile
@@ -0,0 +1,5 @@
1# builds the kprobes example kernel modules;
2# then to use one (as root): insmod <module_name.ko>
3
4obj-$(CONFIG_SAMPLE_KPROBES) += kprobe_example.o jprobe_example.o
5obj-$(CONFIG_SAMPLE_KRETPROBES) += kretprobe_example.o
diff --git a/samples/kprobes/jprobe_example.c b/samples/kprobes/jprobe_example.c
new file mode 100644
index 00000000000..b7541355b92
--- /dev/null
+++ b/samples/kprobes/jprobe_example.c
@@ -0,0 +1,68 @@
1/*
2 * Here's a sample kernel module showing the use of jprobes to dump
3 * the arguments of do_fork().
4 *
5 * For more information on theory of operation of jprobes, see
6 * Documentation/kprobes.txt
7 *
8 * Build and insert the kernel module as done in the kprobe example.
9 * You will see the trace data in /var/log/messages and on the
10 * console whenever do_fork() is invoked to create a new process.
11 * (Some messages may be suppressed if syslogd is configured to
12 * eliminate duplicate messages.)
13 */
14
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/kprobes.h>
18
19/*
20 * Jumper probe for do_fork.
21 * Mirror principle enables access to arguments of the probed routine
22 * from the probe handler.
23 */
24
25/* Proxy routine having the same arguments as actual do_fork() routine */
26static long jdo_fork(unsigned long clone_flags, unsigned long stack_start,
27 struct pt_regs *regs, unsigned long stack_size,
28 int __user *parent_tidptr, int __user *child_tidptr)
29{
30 printk(KERN_INFO "jprobe: clone_flags = 0x%lx, stack_size = 0x%lx,"
31 " regs = 0x%p\n",
32 clone_flags, stack_size, regs);
33
34 /* Always end with a call to jprobe_return(). */
35 jprobe_return();
36 return 0;
37}
38
39static struct jprobe my_jprobe = {
40 .entry = jdo_fork,
41 .kp = {
42 .symbol_name = "do_fork",
43 },
44};
45
46static int __init jprobe_init(void)
47{
48 int ret;
49
50 ret = register_jprobe(&my_jprobe);
51 if (ret < 0) {
52 printk(KERN_INFO "register_jprobe failed, returned %d\n", ret);
53 return -1;
54 }
55 printk(KERN_INFO "Planted jprobe at %p, handler addr %p\n",
56 my_jprobe.kp.addr, my_jprobe.entry);
57 return 0;
58}
59
60static void __exit jprobe_exit(void)
61{
62 unregister_jprobe(&my_jprobe);
63 printk(KERN_INFO "jprobe at %p unregistered\n", my_jprobe.kp.addr);
64}
65
66module_init(jprobe_init)
67module_exit(jprobe_exit)
68MODULE_LICENSE("GPL");
diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
new file mode 100644
index 00000000000..a681998a871
--- /dev/null
+++ b/samples/kprobes/kprobe_example.c
@@ -0,0 +1,91 @@
1/*
2 * NOTE: This example is works on x86 and powerpc.
3 * Here's a sample kernel module showing the use of kprobes to dump a
4 * stack trace and selected registers when do_fork() is called.
5 *
6 * For more information on theory of operation of kprobes, see
7 * Documentation/kprobes.txt
8 *
9 * You will see the trace data in /var/log/messages and on the console
10 * whenever do_fork() is invoked to create a new process.
11 */
12
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/kprobes.h>
16
17/* For each probe you need to allocate a kprobe structure */
18static struct kprobe kp = {
19 .symbol_name = "do_fork",
20};
21
22/* kprobe pre_handler: called just before the probed instruction is executed */
23static int handler_pre(struct kprobe *p, struct pt_regs *regs)
24{
25#ifdef CONFIG_X86
26 printk(KERN_INFO "pre_handler: p->addr = 0x%p, ip = %lx,"
27 " flags = 0x%lx\n",
28 p->addr, regs->ip, regs->flags);
29#endif
30#ifdef CONFIG_PPC
31 printk(KERN_INFO "pre_handler: p->addr = 0x%p, nip = 0x%lx,"
32 " msr = 0x%lx\n",
33 p->addr, regs->nip, regs->msr);
34#endif
35
36 /* A dump_stack() here will give a stack backtrace */
37 return 0;
38}
39
40/* kprobe post_handler: called after the probed instruction is executed */
41static void handler_post(struct kprobe *p, struct pt_regs *regs,
42 unsigned long flags)
43{
44#ifdef CONFIG_X86
45 printk(KERN_INFO "post_handler: p->addr = 0x%p, flags = 0x%lx\n",
46 p->addr, regs->flags);
47#endif
48#ifdef CONFIG_PPC
49 printk(KERN_INFO "post_handler: p->addr = 0x%p, msr = 0x%lx\n",
50 p->addr, regs->msr);
51#endif
52}
53
54/*
55 * fault_handler: this is called if an exception is generated for any
56 * instruction within the pre- or post-handler, or when Kprobes
57 * single-steps the probed instruction.
58 */
59static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
60{
61 printk(KERN_INFO "fault_handler: p->addr = 0x%p, trap #%dn",
62 p->addr, trapnr);
63 /* Return 0 because we don't handle the fault. */
64 return 0;
65}
66
67static int __init kprobe_init(void)
68{
69 int ret;
70 kp.pre_handler = handler_pre;
71 kp.post_handler = handler_post;
72 kp.fault_handler = handler_fault;
73
74 ret = register_kprobe(&kp);
75 if (ret < 0) {
76 printk(KERN_INFO "register_kprobe failed, returned %d\n", ret);
77 return ret;
78 }
79 printk(KERN_INFO "Planted kprobe at %p\n", kp.addr);
80 return 0;
81}
82
83static void __exit kprobe_exit(void)
84{
85 unregister_kprobe(&kp);
86 printk(KERN_INFO "kprobe at %p unregistered\n", kp.addr);
87}
88
89module_init(kprobe_init)
90module_exit(kprobe_exit)
91MODULE_LICENSE("GPL");
diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
new file mode 100644
index 00000000000..4e764b317d6
--- /dev/null
+++ b/samples/kprobes/kretprobe_example.c
@@ -0,0 +1,106 @@
1/*
2 * kretprobe_example.c
3 *
4 * Here's a sample kernel module showing the use of return probes to
5 * report the return value and total time taken for probed function
6 * to run.
7 *
8 * usage: insmod kretprobe_example.ko func=<func_name>
9 *
10 * If no func_name is specified, do_fork is instrumented
11 *
12 * For more information on theory of operation of kretprobes, see
13 * Documentation/kprobes.txt
14 *
15 * Build and insert the kernel module as done in the kprobe example.
16 * You will see the trace data in /var/log/messages and on the console
17 * whenever the probed function returns. (Some messages may be suppressed
18 * if syslogd is configured to eliminate duplicate messages.)
19 */
20
21#include <linux/kernel.h>
22#include <linux/module.h>
23#include <linux/kprobes.h>
24#include <linux/ktime.h>
25#include <linux/limits.h>
26
27static char func_name[NAME_MAX] = "do_fork";
28module_param_string(func, func_name, NAME_MAX, S_IRUGO);
29MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
30 " function's execution time");
31
32/* per-instance private data */
33struct my_data {
34 ktime_t entry_stamp;
35};
36
37/* Here we use the entry_hanlder to timestamp function entry */
38static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
39{
40 struct my_data *data;
41
42 if (!current->mm)
43 return 1; /* Skip kernel threads */
44
45 data = (struct my_data *)ri->data;
46 data->entry_stamp = ktime_get();
47 return 0;
48}
49
50/*
51 * Return-probe handler: Log the return value and duration. Duration may turn
52 * out to be zero consistently, depending upon the granularity of time
53 * accounting on the platform.
54 */
55static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
56{
57 int retval = regs_return_value(regs);
58 struct my_data *data = (struct my_data *)ri->data;
59 s64 delta;
60 ktime_t now;
61
62 now = ktime_get();
63 delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
64 printk(KERN_INFO "%s returned %d and took %lld ns to execute\n",
65 func_name, retval, (long long)delta);
66 return 0;
67}
68
69static struct kretprobe my_kretprobe = {
70 .handler = ret_handler,
71 .entry_handler = entry_handler,
72 .data_size = sizeof(struct my_data),
73 /* Probe up to 20 instances concurrently. */
74 .maxactive = 20,
75};
76
77static int __init kretprobe_init(void)
78{
79 int ret;
80
81 my_kretprobe.kp.symbol_name = func_name;
82 ret = register_kretprobe(&my_kretprobe);
83 if (ret < 0) {
84 printk(KERN_INFO "register_kretprobe failed, returned %d\n",
85 ret);
86 return -1;
87 }
88 printk(KERN_INFO "Planted return probe at %s: %p\n",
89 my_kretprobe.kp.symbol_name, my_kretprobe.kp.addr);
90 return 0;
91}
92
93static void __exit kretprobe_exit(void)
94{
95 unregister_kretprobe(&my_kretprobe);
96 printk(KERN_INFO "kretprobe at %p unregistered\n",
97 my_kretprobe.kp.addr);
98
99 /* nmissed > 0 suggests that maxactive was set too low. */
100 printk(KERN_INFO "Missed probing %d instances of %s\n",
101 my_kretprobe.nmissed, my_kretprobe.kp.symbol_name);
102}
103
104module_init(kretprobe_init)
105module_exit(kretprobe_exit)
106MODULE_LICENSE("GPL");