From c09eee098bd347608cdccac0fc9f17000d255bb5 Mon Sep 17 00:00:00 2001
From: Mao Han <han_mao@linux.alibaba.com>
Date: Wed, 12 Oct 2022 22:25:06 +0800
Subject: [PATCH] Add mmap_rnd_bits routine for riscv64

Signed-off-by: Mao Han <han_mao@linux.alibaba.com>
Change-Id: Ide793f4365fee67f30e35302365c4a7a5ba1f021
---
 init/security.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/init/security.cpp b/init/security.cpp
index 0e9f6c2b4..2ecf6872d 100644
--- a/init/security.cpp
+++ b/init/security.cpp
@@ -116,6 +116,13 @@ Result<void> SetMmapRndBitsAction(const BuiltinArguments&) {
     if (SetMmapRndBitsMin(33, 24, false) && (!Has32BitAbi() || SetMmapRndBitsMin(16, 16, true))) {
         return {};
     }
+#elif defined(__riscv)
+    // TODO: sv48 and sv57 were both added to the kernel this year, so we
+    // probably just need some kernel fixes to enable higher ASLR randomization,
+    // but for now 24 is the maximum that the kernel supports.
+    if (SetMmapRndBitsMin(24, 18, false)) {
+        return {};
+    }
 #elif defined(__x86_64__)
     // x86_64 supports 28 - 32 rnd bits, but Android wants to ensure that the
     // theoretical maximum of 32 bits is always supported and used.