v4.19.13 snapshot.
diff --git a/mm/rodata_test.c b/mm/rodata_test.c
new file mode 100644
index 0000000..d908c87
--- /dev/null
+++ b/mm/rodata_test.c
@@ -0,0 +1,57 @@
+/*
+ * 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");
+}