linux/mm/rodata_test.c
Christophe Leroy a872eb2131 mm: fix RODATA_TEST failure "rodata_test: test data was not read only"
On powerpc, RODATA_TEST fails with message the following messages:

  Freeing unused kernel memory: 528K
  rodata_test: test data was not read only

This is because GCC allocates it to .data section:

  c0695034 g     O .data	00000004 rodata_test_data

Since commit 056b9d8a76 ("mm: remove rodata_test_data export, add
pr_fmt"), rodata_test_data is used only inside rodata_test.c By
declaring it static, it gets properly allocated into .rodata section
instead of .data:

  c04df710 l     O .rodata	00000004 rodata_test_data

Fixes: 056b9d8a76 ("mm: remove rodata_test_data export, add pr_fmt")
Link: http://lkml.kernel.org/r/20170921093729.1080368AC1@po15668-vm-win7.idsi0.si.c-s.fr
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jinbum Park <jinb.park7@gmail.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-10-03 17:54:24 -07:00

58 lines
1.4 KiB
C

/*
* rodata_test.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.
*/
#define pr_fmt(fmt) "rodata_test: " fmt
#include <linux/uaccess.h>
#include <asm/sections.h>
static const int rodata_test_data = 0xC3;
void rodata_test(void)
{
unsigned long start, end;
int zero = 0;
/* test 1: read the value */
/* If this test fails, some previous testrun has clobbered the state */
if (!rodata_test_data) {
pr_err("test 1 fails (start data)\n");
return;
}
/* test 2: write to the variable; this should fault */
if (!probe_kernel_write((void *)&rodata_test_data,
(void *)&zero, sizeof(zero))) {
pr_err("test data was not read only\n");
return;
}
/* test 3: check the value hasn't changed */
if (rodata_test_data == zero) {
pr_err("test data was changed\n");
return;
}
/* test 4: check if the rodata section is PAGE_SIZE aligned */
start = (unsigned long)__start_rodata;
end = (unsigned long)__end_rodata;
if (start & (PAGE_SIZE - 1)) {
pr_err("start of .rodata is not page size aligned\n");
return;
}
if (end & (PAGE_SIZE - 1)) {
pr_err("end of .rodata is not page size aligned\n");
return;
}
pr_info("all tests were successful\n");
}