[PATCH 3/6] rodata_test: refactor tests

[Igor Stoppa <igor.stoppa@gmail.com>]

Refactor the test cases, in preparation for using them also for testing
__wr_after_init memory.

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: 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..3c1e515ca9b1 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;
 	}
+	return true;
+}
 
-	pr_info("all tests were successful\n");
+void rodata_test(void)
+{
+	if (test_data("rodata", &rodata_test_data,
+		      (unsigned long)&__start_rodata,
+		      (unsigned long)&__end_rodata))
+		pr_info("all tests were successful\n");
 }
-- 
2.19.1