/* * 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> 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" ".section __ex_table,\"a\"\n" " .align 16\n" #ifdef CONFIG_X86_32 " .long 0b,2b\n" #else " .quad 0b,2b\n" #endif ".previous" : [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>");