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/uaccess.h>
  11#include <asm/sections.h>
  12
  13static const int rodata_test_data = 0xC3;
  14
  15void rodata_test(void)
  16{
  17        unsigned long start, end;
  18        int zero = 0;
  19
  20        /* test 1: read the value */
  21        /* If this test fails, some previous testrun has clobbered the state */
  22        if (!rodata_test_data) {
  23                pr_err("test 1 fails (start data)\n");
  24                return;
  25        }
  26
  27        /* test 2: write to the variable; this should fault */
  28        if (!probe_kernel_write((void *)&rodata_test_data,
  29                                (void *)&zero, sizeof(zero))) {
  30                pr_err("test data was not read only\n");
  31                return;
  32        }
  33
  34        /* test 3: check the value hasn't changed */
  35        if (rodata_test_data == zero) {
  36                pr_err("test data was changed\n");
  37                return;
  38        }
  39
  40        /* test 4: check if the rodata section is PAGE_SIZE aligned */
  41        start = (unsigned long)__start_rodata;
  42        end = (unsigned long)__end_rodata;
  43        if (start & (PAGE_SIZE - 1)) {
  44                pr_err("start of .rodata is not page size aligned\n");
  45                return;
  46        }
  47        if (end & (PAGE_SIZE - 1)) {
  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