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x86: add testcases for RODATA and NX protections/attributes

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Latest update; I now have 4 NX tests, but 2 fail so they're #if 0'd.
I also cleaned up the NX test code quite a bit, and got rid of the ugly
exception table sorting stuff.

From: Arjan van de Ven <arjan@linux.intel.com>

This patch adds testcases for the CONFIG_DEBUG_RODATA configuration option
as well as the NX CPU feature/mappings. Both testcases can move to tests/
once that patch gets merged into mainline.
(I'm half considering moving the rodata test into mm/init.c but I'll
wait with that until init.c is unified)

As part of this I had to fix a not-quite-right alignment in the vmlinux.lds.h
for the RODATA sections, which lead to 1 page less being marked read only.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Arjan van de Ven
2008-01-30 13:34:08 +01:00
committed by Ingo Molnar
parent adafdf6a4e
commit edeed30589
6 changed files with 276 additions and 0 deletions
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86
arch/x86/kernel/test_rodata.c Normal file
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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/sections.h>
extern int rodata_test_data;
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"
".section __ex_table,\"a\"\n"
" .align 16\n"
#ifdef CONFIG_X86_32
" .long 0b,2b\n"
#else
" .quad 0b,2b\n"
#endif
".previous"
: [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 failes (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 the DEBUG_RODATA infrastructure");
MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");