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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 commit056b9d8a76("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>
57 lines
1.4 KiB
C
57 lines
1.4 KiB
C
/*
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* rodata_test.c: functional test for mark_rodata_ro function
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*
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* (C) Copyright 2008 Intel Corporation
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* Author: Arjan van de Ven <arjan@linux.intel.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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*/
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#define pr_fmt(fmt) "rodata_test: " fmt
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#include <linux/uaccess.h>
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#include <asm/sections.h>
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static const int rodata_test_data = 0xC3;
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void rodata_test(void)
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{
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unsigned long start, end;
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int zero = 0;
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/* test 1: read the value */
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/* If this test fails, some previous testrun has clobbered the state */
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if (!rodata_test_data) {
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pr_err("test 1 fails (start data)\n");
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return;
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}
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/* test 2: write to the variable; this should fault */
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if (!probe_kernel_write((void *)&rodata_test_data,
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(void *)&zero, sizeof(zero))) {
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pr_err("test data was not read only\n");
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return;
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}
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/* test 3: check the value hasn't changed */
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if (rodata_test_data == zero) {
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pr_err("test data was changed\n");
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return;
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}
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/* test 4: check if the rodata section is PAGE_SIZE aligned */
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start = (unsigned long)__start_rodata;
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end = (unsigned long)__end_rodata;
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if (start & (PAGE_SIZE - 1)) {
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pr_err("start of .rodata is not page size aligned\n");
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return;
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}
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if (end & (PAGE_SIZE - 1)) {
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pr_err("end of .rodata is not page size aligned\n");
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return;
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}
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pr_info("all tests were successful\n");
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}
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