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 <asm/sections.h> 13 14 static const int rodata_test_data = 0xC3; 15 rodata_test(void)16 void rodata_test(void) 17 { 18 unsigned long start, end; 19 int zero = 0; 20 21 /* test 1: read the value */ 22 /* If this test fails, some previous testrun has clobbered the state */ 23 if (!rodata_test_data) { 24 pr_err("test 1 fails (start data)\n"); 25 return; 26 } 27 28 /* test 2: write to the variable; this should fault */ 29 if (!copy_to_kernel_nofault((void *)&rodata_test_data, 30 (void *)&zero, sizeof(zero))) { 31 pr_err("test data was not read only\n"); 32 return; 33 } 34 35 /* test 3: check the value hasn't changed */ 36 if (rodata_test_data == zero) { 37 pr_err("test data was changed\n"); 38 return; 39 } 40 41 /* test 4: check if the rodata section is PAGE_SIZE aligned */ 42 start = (unsigned long)__start_rodata; 43 end = (unsigned long)__end_rodata; 44 if (start & (PAGE_SIZE - 1)) { 45 pr_err("start of .rodata is not page size aligned\n"); 46 return; 47 } 48 if (end & (PAGE_SIZE - 1)) { 49 pr_err("end of .rodata is not page size aligned\n"); 50 return; 51 } 52 53 pr_info("all tests were successful\n"); 54 } 55