From 7a64bdbbcf14023370b90b22de73c2f61a6f84ac Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Sun, 4 Apr 2021 00:11:00 +0200
Subject: Implemented basic user program ASLR

---
 libs/libc/random.c | 48 +++++++++++++++++++-----------------------------
 1 file changed, 19 insertions(+), 29 deletions(-)

(limited to 'libs/libc/random.c')

diff --git a/libs/libc/random.c b/libs/libc/random.c
index 6296407..983357f 100644
--- a/libs/libc/random.c
+++ b/libs/libc/random.c
@@ -15,46 +15,36 @@ void srand(u32 seed)
 	g_seed = seed;
 }
 
-u32 rdrand(void)
+static u32 default_rand(void)
 {
-#ifdef KERNEL
-	if (!(cpu_features.ecx & CPUID_FEAT_ECX_RDRND))
-		return rand();
-
-	u32 rd;
-	__asm__ volatile("1:\n"
-			 "rdrand %0\n"
-			 "jnc 1b\n"
-			 : "=r"(rd));
-	return rd;
-#else
-	return rand();
-#endif
+	g_seed = g_seed * 1103515245 + 12345;
+	return (g_seed >> 16) & 0x7FFF;
 }
 
-u32 rdseed(void)
+u32 rand(void)
 {
 #ifdef KERNEL
-	if (!(cpu_extended_features.ebx & CPUID_EXT_FEAT_EBX_RDSEED))
-		return rand();
-
 	u32 rd;
-	__asm__ volatile("1:\n"
-			 "rdseed %0\n"
-			 "jnc 1b\n"
-			 : "=r"(rd));
+	if (cpu_extended_features.ebx & CPUID_EXT_FEAT_EBX_RDSEED) {
+		__asm__ volatile("1:\n"
+				 "rdseed %0\n"
+				 "jnc 1b\n"
+				 : "=r"(rd));
+	} else if (cpu_features.ecx & CPUID_FEAT_ECX_RDRND) {
+		__asm__ volatile("1:\n"
+				 "rdrand %0\n"
+				 "jnc 1b\n"
+				 : "=r"(rd));
+	} else {
+		rd = default_rand();
+	}
+
 	return rd;
 #else
-	return rand();
+	return default_rand();
 #endif
 }
 
-u32 rand(void)
-{
-	g_seed = g_seed * 1103515245 + 12345;
-	return (g_seed >> 16) & 0x7FFF;
-}
-
 char *randstr(u32 size)
 {
 	if (!size)
-- 
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