// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * test_kprobes.c - simple sanity test for *probes
   *
   * Copyright IBM Corp. 2008

   */

  #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
  ");
  	}

  	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
  ");
  	}

  	if (preh_val != (rand1 / div_factor)) {
  		handler_errors++;

  		pr_err("incorrect value in post_handler
  ");

  	}
  	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
  ", ret);

  		return ret;
  	}

  	ret = target(rand1);

  	unregister_kprobe(&kp);
  
  	if (preh_val == 0) {

  		pr_err("kprobe pre_handler not called
  ");

  		handler_errors++;
  	}
  
  	if (posth_val == 0) {

  		pr_err("kprobe post_handler not called
  ");

  		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
  ");

  	}
  	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
  ", ret);

  		return ret;
  	}
  
  	preh_val = 0;
  	posth_val = 0;
  	ret = target(rand1);
  
  	if (preh_val == 0) {

  		pr_err("kprobe pre_handler not called
  ");

  		handler_errors++;
  	}
  
  	if (posth_val == 0) {

  		pr_err("kprobe post_handler not called
  ");

  		handler_errors++;
  	}
  
  	preh_val = 0;
  	posth_val = 0;
  	ret = target2(rand1);
  
  	if (preh_val == 0) {

  		pr_err("kprobe pre_handler2 not called
  ");

  		handler_errors++;
  	}
  
  	if (posth_val == 0) {

  		pr_err("kprobe post_handler2 not called
  ");

  		handler_errors++;
  	}
  
  	unregister_kprobes(kps, 2);
  	return 0;
  
  }

  #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
  ");
  	}

  	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
  ");
  	}

  	if (ret != (rand1 / div_factor)) {
  		handler_errors++;

  		pr_err("incorrect value in kretprobe handler
  ");

  	}

  	if (krph_val == 0) {
  		handler_errors++;

  		pr_err("call to kretprobe entry handler failed
  ");

  	}

  	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
  ", ret);

  		return ret;
  	}

  	ret = target(rand1);

  	unregister_kretprobe(&rp);

  	if (krph_val != rand1) {

  		pr_err("kretprobe handler not called
  ");

  		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
  ");

  	}
  	if (krph_val == 0) {
  		handler_errors++;

  		pr_err("call to kretprobe entry handler failed
  ");

  	}
  
  	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
  ", ret);

  		return ret;
  	}
  
  	krph_val = 0;
  	ret = target(rand1);
  	if (krph_val != rand1) {

  		pr_err("kretprobe handler not called
  ");

  		handler_errors++;
  	}
  
  	krph_val = 0;
  	ret = target2(rand1);
  	if (krph_val != rand1) {

  		pr_err("kretprobe handler2 not called
  ");

  		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
  ");

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

  	ret = test_kprobes();
  	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
  ", errors, num_tests);

  	else if (handler_errors)

  		pr_err("BUG: %d error(s) running handlers
  ", handler_errors);

  	else

  		pr_info("passed successfully
  ");

  
  	return 0;
  }