root/kernel/test_kprobes.c

DEFINITIONS

1. kprobe_target
2. kp_pre_handler
3. kp_post_handler
4. test_kprobe
5. j_kprobe_target
6. test_jprobe
7. entry_handler
8. return_handler
9. test_kretprobe
10. init_test_probes

/*
 * 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;
}