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/*
* 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>
#include <asm/asm.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"
_ASM_EXTABLE(0b,2b)
: [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 fails (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 marking rodata as read-only");
MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
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