text: /*
   * test_rodata.c: functional test for mark_rodata_ro function
   *
   * (C) Copyright 2008 Intel Corporation
   * Author: Arjan van de Ven <arjan@linux.intel.com>
   *
   * 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; version 2
   * of the License.
   */
  #include <linux/module.h>
  #include <asm/cacheflush.h>
  #include <asm/sections.h>
  #include <asm/asm.h>
  
  int rodata_test(void)
  {
  	unsigned long result;
  	unsigned long start, end;
  
  	/* test 1: read the value */
  	/* If this test fails, some previous testrun has clobbered the state */
  	if (!rodata_test_data) {
  		printk(KERN_ERR "rodata_test: test 1 fails (start data)\n");
  		return -ENODEV;
  	}
  
  	/* test 2: write to the variable; this should fault */
  	/*
  	 * If this test fails, we managed to overwrite the data
  	 *
  	 * This is written in assembly to be able to catch the
  	 * exception that is supposed to happen in the correct
  	 * case
  	 */
  
  	result = 1;
  	asm volatile(
  		"0:	mov %[zero],(%[rodata_test])\n"
  		"	mov %[zero], %[rslt]\n"
  		"1:\n"
  		".section .fixup,\"ax\"\n"
  		"2:	jmp 1b\n"
  		".previous\n"
  		_ASM_EXTABLE(0b,2b)
  		: [rslt] "=r" (result)
  		: [rodata_test] "r" (&rodata_test_data), [zero] "r" (0UL)
  	);
  
  
  	if (!result) {
  		printk(KERN_ERR "rodata_test: test data was not read only\n");
  		return -ENODEV;
  	}
  
  	/* test 3: check the value hasn't changed */
  	/* If this test fails, we managed to overwrite the data */
  	if (!rodata_test_data) {
  		printk(KERN_ERR "rodata_test: Test 3 failes (end data)\n");
  		return -ENODEV;
  	}
  	/* test 4: check if the rodata section is 4Kb aligned */
  	start = (unsigned long)__start_rodata;
  	end = (unsigned long)__end_rodata;
  	if (start & (PAGE_SIZE - 1)) {
  		printk(KERN_ERR "rodata_test: .rodata is not 4k aligned\n");
  		return -ENODEV;
  	}
  	if (end & (PAGE_SIZE - 1)) {
  		printk(KERN_ERR "rodata_test: .rodata end is not 4k aligned\n");
  		return -ENODEV;
  	}
  
  	return 0;
  }
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Testcase for the DEBUG_RODATA infrastructure");
  MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
  