From da4486d93ab21ae2a719244a40ec897d94b62332 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <slankes@eonerc.rwth-aachen.de>
Date: Sun, 20 Nov 2016 00:48:22 +0100
Subject: [PATCH] add rdrand support

If available, HermitCore supports rdrand to generate random number.
LwIP uses this instruction to support DNSSec.
---
 hermit/arch/x86/include/asm/processor.h | 21 +++++++++++++++++++++
 hermit/arch/x86/kernel/processor.c      |  3 ++-
 hermit/lwip                             |  2 +-
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/hermit/arch/x86/include/asm/processor.h b/hermit/arch/x86/include/asm/processor.h
index 5b21f28c8..b8d672cc7 100644
--- a/hermit/arch/x86/include/asm/processor.h
+++ b/hermit/arch/x86/include/asm/processor.h
@@ -76,6 +76,7 @@ extern "C" {
 #define CPU_FEATURE_XSAVE			(1 << 26)
 #define CPU_FEATURE_OSXSAVE			(1 << 27)
 #define CPU_FEATURE_AVX				(1 << 28)
+#define CPU_FEATURE_RDRAND			(1 << 30)
 #define CPU_FEATURE_HYPERVISOR			(1 << 31)
 
 // CPUID.80000001H:EDX feature list
@@ -389,6 +390,10 @@ inline static uint32_t has_avx(void) {
 	return (cpu_info.feature2 & CPU_FEATURE_AVX);
 }
 
+inline static uint32_t has_rdrand(void) {
+	return (cpu_info.feature2 & CPU_FEATURE_RDRAND);
+}
+
 inline static uint32_t on_hypervisor(void) {
 	return (cpu_info.feature2 & CPU_FEATURE_HYPERVISOR);
 }
@@ -452,6 +457,22 @@ static inline void clts(void)
 	asm volatile("clts");
 }
 
+/** @brief Read a random number
+ *
+ *  Returns a hardware generated random value.
+ */
+inline static uint32_t rdrand(void)
+{
+	uint32_t val;
+	uint8_t rc;
+
+	do {
+		asm volatile("rdrand %0 ; setc %1" : "=r" (val), "=qm" (rc));
+	} while(rc == 0); // rc == 0: underflow
+
+	return val;
+}
+
 /** @brief Read out time stamp counter
  *
  * The rdtsc instruction puts a 64 bit time stamp value
diff --git a/hermit/arch/x86/kernel/processor.c b/hermit/arch/x86/kernel/processor.c
index 832d7b2ff..ac37161fd 100644
--- a/hermit/arch/x86/kernel/processor.c
+++ b/hermit/arch/x86/kernel/processor.c
@@ -554,7 +554,7 @@ int cpu_detection(void) {
 		a = b = c = d = 0;
                 cpuid(1, &a, &b, &cpu_info.feature2, &cpu_info.feature1);
 
-		LOG_INFO("CPU features: %s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
+		LOG_INFO("CPU features: %s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
 			has_sse() ? "SSE " : "",
 			has_sse2() ? "SSE2 " : "",
 			has_sse3() ? "SSE3 " : "",
@@ -562,6 +562,7 @@ int cpu_detection(void) {
 			has_sse4_2() ? "SSE4.2 " : "",
 			has_avx() ? "AVX " : "",
 			has_avx2() ? "AVX2 " : "",
+			has_rdrand() ? "RDRAND " : "",
 			has_fma() ? "FMA " : "",
 			has_movbe() ? "MOVBE " : "",
 			has_x2apic() ? "X2APIC " : "",
diff --git a/hermit/lwip b/hermit/lwip
index 594aea714..3dbc27233 160000
--- a/hermit/lwip
+++ b/hermit/lwip
@@ -1 +1 @@
-Subproject commit 594aea71498c7c11850186f9b7d85e95ee34ac68
+Subproject commit 3dbc272333882dd02029ef9c45bbcb4c59ee7a6d