/*
 * 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.
 */

#define pr_fmt(fmt) "Kprobe smoke test: " fmt

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

#define div_factor 3

static u32 rand1, preh_val, posth_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)
{
        if (preemptible()) {
                handler_errors++;
                pr_err("pre-handler is preemptible\n");
        }
        preh_val = (rand1 / div_factor);
        return 0;
}

static void kp_post_handler(struct kprobe *p, struct pt_regs *regs,
                unsigned long flags)
{
        if (preemptible()) {
                handler_errors++;
                pr_err("post-handler is preemptible\n");
        }
        if (preh_val != (rand1 / div_factor)) {
                handler_errors++;
                pr_err("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) {
                pr_err("register_kprobe returned %d\n", ret);
                return ret;
        }

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

        if (preh_val == 0) {
                pr_err("kprobe pre_handler not called\n");
                handler_errors++;
        }

        if (posth_val == 0) {
                pr_err("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++;
                pr_err("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) {
                pr_err("register_kprobes returned %d\n", ret);
                return ret;
        }

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

        if (preh_val == 0) {
                pr_err("kprobe pre_handler not called\n");
                handler_errors++;
        }

        if (posth_val == 0) {
                pr_err("kprobe post_handler not called\n");
                handler_errors++;
        }

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

        if (preh_val == 0) {
                pr_err("kprobe pre_handler2 not called\n");
                handler_errors++;
        }

        if (posth_val == 0) {
                pr_err("kprobe post_handler2 not called\n");
                handler_errors++;
        }

        unregister_kprobes(kps, 2);
        return 0;

}

#if 0
static u32 jph_val;

static u32 j_kprobe_target(u32 value)
{
        if (preemptible()) {
                handler_errors++;
                pr_err("jprobe-handler is preemptible\n");
        }
        if (value != rand1) {
                handler_errors++;
                pr_err("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) {
                pr_err("register_jprobe returned %d\n", ret);
                return ret;
        }

        ret = target(rand1);
        unregister_jprobe(&jp);
        if (jph_val == 0) {
                pr_err("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) {
                pr_err("register_jprobes returned %d\n", ret);
                return ret;
        }

        jph_val = 0;
        ret = target(rand1);
        if (jph_val == 0) {
                pr_err("jprobe handler not called\n");
                handler_errors++;
        }

        jph_val = 0;
        ret = target2(rand1);
        if (jph_val == 0) {
                pr_err("jprobe handler2 not called\n");
                handler_errors++;
        }
        unregister_jprobes(jps, 2);

        return 0;
}
#else
#define test_jprobe() (0)
#define test_jprobes() (0)
#endif
#ifdef CONFIG_KRETPROBES
static u32 krph_val;

static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
        if (preemptible()) {
                handler_errors++;
                pr_err("kretprobe entry handler is preemptible\n");
        }
        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 (preemptible()) {
                handler_errors++;
                pr_err("kretprobe return handler is preemptible\n");
        }
        if (ret != (rand1 / div_factor)) {
                handler_errors++;
                pr_err("incorrect value in kretprobe handler\n");
        }
        if (krph_val == 0) {
                handler_errors++;
                pr_err("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) {
                pr_err("register_kretprobe returned %d\n", ret);
                return ret;
        }

        ret = target(rand1);
        unregister_kretprobe(&rp);
        if (krph_val != rand1) {
                pr_err("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++;
                pr_err("incorrect value in kretprobe handler2\n");
        }
        if (krph_val == 0) {
                handler_errors++;
                pr_err("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) {
                pr_err("register_kretprobe returned %d\n", ret);
                return ret;
        }

        krph_val = 0;
        ret = target(rand1);
        if (krph_val != rand1) {
                pr_err("kretprobe handler not called\n");
                handler_errors++;
        }

        krph_val = 0;
        ret = target2(rand1);
        if (krph_val != rand1) {
                pr_err("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 = prandom_u32();
        } while (rand1 <= div_factor);

        pr_info("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)
                pr_err("BUG: %d out of %d tests failed\n", errors, num_tests);
        else if (handler_errors)
                pr_err("BUG: %d error(s) running handlers\n", handler_errors);
        else
                pr_info("passed successfully\n");

        return 0;
}