LXR linux/mm/rodata

   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
  14static const int rodata_test_data = 0xC3;
  15
  16void 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