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/*
* test_kprobes.c - simple sanity test for *probes
*
* Copyright IBM Corp. 2008
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it would be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU General Public License for more details.
*/

#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/random.h>

#define div_factor 3

static u32 rand1, preh_val, posth_val, jph_val;
static int errors, handler_errors, num_tests;

static noinline u32 kprobe_target(u32 value)
{
/*
* gcc ignores noinline on some architectures unless we stuff
* sufficient lard into the function. The get_kprobe() here is
* just for that.
*
* NOTE: We aren't concerned about the correctness of get_kprobe()
* here; hence, this call is neither under !preempt nor with the
* kprobe_mutex held. This is fine(tm)
*/
if (get_kprobe((void *)0xdeadbeef))
printk(KERN_INFO "Kprobe smoke test: probe on 0xdeadbeef!\n");

return (value / div_factor);
}

static int kp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
preh_val = (rand1 / div_factor);
return 0;
}

static void kp_post_handler(struct kprobe *p, struct pt_regs *regs,
unsigned long flags)
{
if (preh_val != (rand1 / div_factor)) {
handler_errors++;
printk(KERN_ERR "Kprobe smoke test failed: "
"incorrect value in post_handler\n");
}
posth_val = preh_val + div_factor;
}

static struct kprobe kp = {
.symbol_name = "kprobe_target",
.pre_handler = kp_pre_handler,
.post_handler = kp_post_handler
};

static int test_kprobe(void)
{
int ret;

ret = register_kprobe(&kp);
if (ret < 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"register_kprobe returned %d\n", ret);
return ret;
}

ret = kprobe_target(rand1);
unregister_kprobe(&kp);

if (preh_val == 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"kprobe pre_handler not called\n");
handler_errors++;
}

if (posth_val == 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"kprobe post_handler not called\n");
handler_errors++;
}

return 0;
}

static u32 j_kprobe_target(u32 value)
{
if (value != rand1) {
handler_errors++;
printk(KERN_ERR "Kprobe smoke test failed: "
"incorrect value in jprobe handler\n");
}

jph_val = rand1;
jprobe_return();
return 0;
}

static struct jprobe jp = {
.entry = j_kprobe_target,
.kp.symbol_name = "kprobe_target"
};

static int test_jprobe(void)
{
int ret;

ret = register_jprobe(&jp);
if (ret < 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"register_jprobe returned %d\n", ret);
return ret;
}

ret = kprobe_target(rand1);
unregister_jprobe(&jp);
if (jph_val == 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"jprobe handler not called\n");
handler_errors++;
}

return 0;
}

#ifdef CONFIG_KRETPROBES
static u32 krph_val;

static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
krph_val = (rand1 / div_factor);
return 0;
}

static int return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
unsigned long ret = regs_return_value(regs);

if (ret != (rand1 / div_factor)) {
handler_errors++;
printk(KERN_ERR "Kprobe smoke test failed: "
"incorrect value in kretprobe handler\n");
}
if (krph_val == 0) {
handler_errors++;
printk(KERN_ERR "Kprobe smoke test failed: "
"call to kretprobe entry handler failed\n");
}

krph_val = rand1;
return 0;
}

static struct kretprobe rp = {
.handler = return_handler,
.entry_handler = entry_handler,
.kp.symbol_name = "kprobe_target"
};

static int test_kretprobe(void)
{
int ret;

ret = register_kretprobe(&rp);
if (ret < 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"register_kretprobe returned %d\n", ret);
return ret;
}

ret = kprobe_target(rand1);
unregister_kretprobe(&rp);
if (krph_val != rand1) {
printk(KERN_ERR "Kprobe smoke test failed: "
"kretprobe handler not called\n");
handler_errors++;
}

return 0;
}
#endif /* CONFIG_KRETPROBES */

int init_test_probes(void)
{
int ret;

do {
rand1 = random32();
} while (rand1 <= div_factor);

printk(KERN_INFO "Kprobe smoke test started\n");
num_tests++;
ret = test_kprobe();
if (ret < 0)
errors++;

num_tests++;
ret = test_jprobe();
if (ret < 0)
errors++;

#ifdef CONFIG_KRETPROBES
num_tests++;
ret = test_kretprobe();
if (ret < 0)
errors++;
#endif /* CONFIG_KRETPROBES */

if (errors)
printk(KERN_ERR "BUG: Kprobe smoke test: %d out of "
"%d tests failed\n", errors, num_tests);
else if (handler_errors)
printk(KERN_ERR "BUG: Kprobe smoke test: %d error(s) "
"running handlers\n", handler_errors);
else
printk(KERN_INFO "Kprobe smoke test passed successfully\n");

return 0;
}
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