From 48fae4a971b8978d352918e2825e1c0e3c5706fd Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Sun, 18 Sep 2022 15:22:43 +0200
Subject: [PATCH] Cache RDSEED and RDRAND presence

---
 kernel/src/rand/Init.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/src/rand/Init.cpp b/kernel/src/rand/Init.cpp
index 65dc9531..d91d7d91 100644
--- a/kernel/src/rand/Init.cpp
+++ b/kernel/src/rand/Init.cpp
@@ -10,6 +10,8 @@
 static uint64_t state = 0xf5026f5ae96319e9;
 
 extern "C" int _test_rdseed();
+static bool has_rdrand = false;
+static bool has_rdseed = false;
 
 static uint64_t rdtsc()
 {
@@ -37,6 +39,9 @@ void Mersenne::init()
 {
     kdbgln("Preparing random number generator");
 
+    has_rdrand = CPU::has_feature(CPU::Features::RDRAND);
+    has_rdseed = _test_rdseed();
+
     state ^= (0x45fe1024UL + MOON_MAJOR) * (MOON_MINOR ^ 200UL);
 
     state ^= 0xe0e4f5332ea75b;
@@ -54,9 +59,9 @@ void Mersenne::reseed()
 {
     state ^= rdtsc();
 
-    if (CPU::has_feature(CPU::Features::RDRAND)) { state ^= rdrand(); }
+    if (has_rdrand) { state ^= rdrand(); }
 
-    if (_test_rdseed()) { state ^= rdseed(); }
+    if (has_rdseed) { state ^= rdseed(); }
 
     state ^= rdtsc();