From cd389833d4d11c53b5ea07985e24d34a5ca5df68 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Holz?= <sholz8530@gmail.com>
Date: Thu, 22 Feb 2024 20:02:19 +0100
Subject: [PATCH] Kernel/riscv64: Use TimeManagement as an entropy source for
 now

Better entropy will require us to parse the riscv,isa devicetree
property and then use the Zkr extension, if present.
---
 Kernel/Security/Random.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Kernel/Security/Random.cpp b/Kernel/Security/Random.cpp
index b785dadb922..d4b02c27c40 100644
--- a/Kernel/Security/Random.cpp
+++ b/Kernel/Security/Random.cpp
@@ -77,6 +77,15 @@ UNMAP_AFTER_INIT KernelRng::KernelRng()
             current_time += 0x40b2u;
         }
     }
+#elif ARCH(RISCV64)
+    // Fallback to TimeManagement as entropy
+    dmesgln("KernelRng: Using bad entropy source TimeManagement");
+    auto current_time = static_cast<u64>(TimeManagement::now().milliseconds_since_epoch());
+    for (size_t i = 0; i < pool_count * reseed_threshold; ++i) {
+        add_random_event(current_time, i % 32);
+        current_time *= 0x574au;
+        current_time += 0x40b2u;
+    }
 #else
     dmesgln("KernelRng: No entropy source available!");
 #endif