1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * rodata_test.c: functional test for mark_rodata_ro function 4 * 5 * (C) Copyright 2008 Intel Corporation 6 * Author: Arjan van de Ven <arjan@linux.intel.com> 7 */ 8 #define pr_fmt(fmt) "rodata_test: " fmt 9 10 #include <linux/rodata_test.h> 11 #include <linux/uaccess.h> 12 #include <linux/mm.h> 13 #include <asm/sections.h> 14 15 #define TEST_VALUE 0xC3 16 static const int rodata_test_data = TEST_VALUE; 17 18 void rodata_test(void) 19 { 20 int zero = 0; 21 22 /* test 1: read the value */ 23 /* If this test fails, some previous testrun has clobbered the state */ 24 if (unlikely(READ_ONCE(rodata_test_data) != TEST_VALUE)) { 25 pr_err("test 1 fails (start data)\n"); 26 return; 27 } 28 29 /* test 2: write to the variable; this should fault */ 30 if (!copy_to_kernel_nofault((void *)&rodata_test_data, 31 (void *)&zero, sizeof(zero))) { 32 pr_err("test data was not read only\n"); 33 return; 34 } 35 36 /* test 3: check the value hasn't changed */ 37 if (unlikely(READ_ONCE(rodata_test_data) != TEST_VALUE)) { 38 pr_err("test data was changed\n"); 39 return; 40 } 41 42 /* test 4: check if the rodata section is PAGE_SIZE aligned */ 43 if (!PAGE_ALIGNED(__start_rodata)) { 44 pr_err("start of .rodata is not page size aligned\n"); 45 return; 46 } 47 if (!PAGE_ALIGNED(__end_rodata)) { 48 pr_err("end of .rodata is not page size aligned\n"); 49 return; 50 } 51 52 pr_info("all tests were successful\n"); 53 } 54