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Subject[RFC PATCH v4 09/12] __wr_after_init: rodata_test: refactor tests
Date
Refactor the test cases, in preparation for using them also for testing
__wr_after_init memory, when available.

Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com>

CC: Andy Lutomirski <luto@amacapital.net>
CC: Nadav Amit <nadav.amit@gmail.com>
CC: Matthew Wilcox <willy@infradead.org>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Kees Cook <keescook@chromium.org>
CC: Dave Hansen <dave.hansen@linux.intel.com>
CC: Mimi Zohar <zohar@linux.vnet.ibm.com>
CC: Thiago Jung Bauermann <bauerman@linux.ibm.com>
CC: Ahmed Soliman <ahmedsoliman@mena.vt.edu>
CC: linux-integrity@vger.kernel.org
CC: kernel-hardening@lists.openwall.com
CC: linux-mm@kvack.org
CC: linux-kernel@vger.kernel.org
---
mm/rodata_test.c | 48 ++++++++++++++++++++++++++++--------------------
1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/mm/rodata_test.c b/mm/rodata_test.c
index d908c8769b48..e1349520b436 100644
--- a/mm/rodata_test.c
+++ b/mm/rodata_test.c
@@ -14,44 +14,52 @@
#include <linux/uaccess.h>
#include <asm/sections.h>

-static const int rodata_test_data = 0xC3;
+#define INIT_TEST_VAL 0xC3

-void rodata_test(void)
+static const int rodata_test_data = INIT_TEST_VAL;
+
+static bool test_data(char *data_type, const int *data,
+ unsigned long start, unsigned long end)
{
- 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;
+ if (*data != INIT_TEST_VAL) {
+ pr_err("%s: test 1 fails (init data value)\n", data_type);
+ return false;
}

/* 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;
+ if (!probe_kernel_write((void *)data, (void *)&zero, sizeof(zero))) {
+ pr_err("%s: test data was not read only\n", data_type);
+ return false;
}

/* test 3: check the value hasn't changed */
- if (rodata_test_data == zero) {
- pr_err("test data was changed\n");
- return;
+ if (*data != INIT_TEST_VAL) {
+ pr_err("%s: test data was changed\n", data_type);
+ return false;
}

/* 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;
+ pr_err("%s: start of data is not page size aligned\n",
+ data_type);
+ return false;
}
if (end & (PAGE_SIZE - 1)) {
- pr_err("end of .rodata is not page size aligned\n");
- return;
+ pr_err("%s: end of data is not page size aligned\n",
+ data_type);
+ return false;
}
+ pr_info("%s tests were successful", data_type);
+ return true;
+}

- pr_info("all tests were successful\n");
+void rodata_test(void)
+{
+ test_data("rodata", &rodata_test_data,
+ (unsigned long)&__start_rodata,
+ (unsigned long)&__end_rodata);
}
--
2.19.1
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