1 files changed, 38 insertions, 0 deletions
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
new file mode 100644
index 0000000000..94a269cd1f
--- /dev/null
+++ b/arch/arm64/kernel/kaslr.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016 Linaro Ltd <ard.biesheuvel@linaro.org>
+ */
+
+#include <linux/cache.h>
+#include <linux/init.h>
+#include <linux/printk.h>
+
+#include <asm/cpufeature.h>
+#include <asm/memory.h>
+
+u16 __initdata memstart_offset_seed;
+
+bool __ro_after_init __kaslr_is_enabled = false;
+
+void __init kaslr_init(void)
+{
+	if (cpuid_feature_extract_unsigned_field(arm64_sw_feature_override.val &
+						 arm64_sw_feature_override.mask,
+						 ARM64_SW_FEATURE_OVERRIDE_NOKASLR)) {
+		pr_info("KASLR disabled on command line\n");
+		return;
+	}
+
+	/*
+	 * The KASLR offset modulo MIN_KIMG_ALIGN is taken from the physical
+	 * placement of the image rather than from the seed, so a displacement
+	 * of less than MIN_KIMG_ALIGN means that no seed was provided.
+	 */
+	if (kaslr_offset() < MIN_KIMG_ALIGN) {
+		pr_warn("KASLR disabled due to lack of seed\n");
+		return;
+	}
+
+	pr_info("KASLR enabled\n");
+	__kaslr_is_enabled = true;
+}