// SPDX-License-Identifier: GPL-2.0-only
  /*
   * rodata_test.c: functional test for mark_rodata_ro function
   *
   * (C) Copyright 2008 Intel Corporation
   * Author: Arjan van de Ven <arjan@linux.intel.com>
   */
  #define pr_fmt(fmt) "rodata_test: " fmt
  
  #include <linux/rodata_test.h>
  #include <linux/uaccess.h>
  #include <asm/sections.h>
  
  static const int rodata_test_data = 0xC3;
  
  void rodata_test(void)
  {
  	unsigned long start, end;
  	int zero = 0;
  
  	/* test 1: read the value */
  	/* If this test fails, some previous testrun has clobbered the state */
  	if (!rodata_test_data) {
  		pr_err("test 1 fails (start data)
  ");
  		return;
  	}
  
  	/* test 2: write to the variable; this should fault */
  	if (!copy_to_kernel_nofault((void *)&rodata_test_data,
  				(void *)&zero, sizeof(zero))) {
  		pr_err("test data was not read only
  ");
  		return;
  	}
  
  	/* test 3: check the value hasn't changed */
  	if (rodata_test_data == zero) {
  		pr_err("test data was changed
  ");
  		return;
  	}
  
  	/* test 4: check if the rodata section is PAGE_SIZE aligned */
  	start = (unsigned long)__start_rodata;
  	end = (unsigned long)__end_rodata;
  	if (start & (PAGE_SIZE - 1)) {
  		pr_err("start of .rodata is not page size aligned
  ");
  		return;
  	}
  	if (end & (PAGE_SIZE - 1)) {
  		pr_err("end of .rodata is not page size aligned
  ");
  		return;
  	}
  
  	pr_info("all tests were successful
  ");
  }