test_kprobes.c

Go to the documentation of this file.

/*
 * 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 u32 (*target)(u32 value);
static u32 (*target2)(u32 value);

static noinline u32 kprobe_target(u32 value)
{
    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 = 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 noinline u32 kprobe_target2(u32 value)
{
    return (value / div_factor) + 1;
}

static int kp_pre_handler2(struct kprobe *p, struct pt_regs *regs)
{
    preh_val = (rand1 / div_factor) + 1;
    return 0;
}

static void kp_post_handler2(struct kprobe *p, struct pt_regs *regs,
        unsigned long flags)
{
    if (preh_val != (rand1 / div_factor) + 1) {
        handler_errors++;
        printk(KERN_ERR "Kprobe smoke test failed: "
                "incorrect value in post_handler2\n");
    }
    posth_val = preh_val + div_factor;
}

static struct kprobe kp2 = {
    .symbol_name = "kprobe_target2",
    .pre_handler = kp_pre_handler2,
    .post_handler = kp_post_handler2
};

static int test_kprobes(void)
{
    int ret;
    struct kprobe *kps[2] = {&kp, &kp2};

    /* addr and flags should be cleard for reusing kprobe. */
    kp.addr = NULL;
    kp.flags = 0;
    ret = register_kprobes(kps, 2);
    if (ret < 0) {
        printk(KERN_ERR "Kprobe smoke test failed: "
                "register_kprobes returned %d\n", ret);
        return ret;
    }

    preh_val = 0;
    posth_val = 0;
    ret = target(rand1);

    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++;
    }

    preh_val = 0;
    posth_val = 0;
    ret = target2(rand1);

    if (preh_val == 0) {
        printk(KERN_ERR "Kprobe smoke test failed: "
                "kprobe pre_handler2 not called\n");
        handler_errors++;
    }

    if (posth_val == 0) {
        printk(KERN_ERR "Kprobe smoke test failed: "
                "kprobe post_handler2 not called\n");
        handler_errors++;
    }

    unregister_kprobes(kps, 2);
    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 = 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;
}

static struct jprobe jp2 = {
    .entry          = j_kprobe_target,
    .kp.symbol_name = "kprobe_target2"
};

static int test_jprobes(void)
{
    int ret;
    struct jprobe *jps[2] = {&jp, &jp2};

    /* addr and flags should be cleard for reusing kprobe. */
    jp.kp.addr = NULL;
    jp.kp.flags = 0;
    ret = register_jprobes(jps, 2);
    if (ret < 0) {
        printk(KERN_ERR "Kprobe smoke test failed: "
                "register_jprobes returned %d\n", ret);
        return ret;
    }

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

    jph_val = 0;
    ret = target2(rand1);
    if (jph_val == 0) {
        printk(KERN_ERR "Kprobe smoke test failed: "
                "jprobe handler2 not called\n");
        handler_errors++;
    }
    unregister_jprobes(jps, 2);

    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 = 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;
}

static int return_handler2(struct kretprobe_instance *ri, struct pt_regs *regs)
{
    unsigned long ret = regs_return_value(regs);

    if (ret != (rand1 / div_factor) + 1) {
        handler_errors++;
        printk(KERN_ERR "Kprobe smoke test failed: "
                "incorrect value in kretprobe handler2\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 rp2 = {
    .handler    = return_handler2,
    .entry_handler  = entry_handler,
    .kp.symbol_name = "kprobe_target2"
};

static int test_kretprobes(void)
{
    int ret;
    struct kretprobe *rps[2] = {&rp, &rp2};

    /* addr and flags should be cleard for reusing kprobe. */
    rp.kp.addr = NULL;
    rp.kp.flags = 0;
    ret = register_kretprobes(rps, 2);
    if (ret < 0) {
        printk(KERN_ERR "Kprobe smoke test failed: "
                "register_kretprobe returned %d\n", ret);
        return ret;
    }

    krph_val = 0;
    ret = target(rand1);
    if (krph_val != rand1) {
        printk(KERN_ERR "Kprobe smoke test failed: "
                "kretprobe handler not called\n");
        handler_errors++;
    }

    krph_val = 0;
    ret = target2(rand1);
    if (krph_val != rand1) {
        printk(KERN_ERR "Kprobe smoke test failed: "
                "kretprobe handler2 not called\n");
        handler_errors++;
    }
    unregister_kretprobes(rps, 2);
    return 0;
}
#endif /* CONFIG_KRETPROBES */

int init_test_probes(void)
{
    int ret;

    target = kprobe_target;
    target2 = kprobe_target2;

    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_kprobes();
    if (ret < 0)
        errors++;

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

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

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

    num_tests++;
    ret = test_kretprobes();
    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;
}