From 37f49e37ab4cb5d0bc4c60eb5c6d4dd57db767bb Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 10 May 2024 07:44:59 +0000
Subject: [PATCH] gmac get mac form eeprom

---
 kernel/arch/x86/kernel/cpu/rdrand.c |   37 ++++++++++++++++++++++---------------
 1 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/kernel/arch/x86/kernel/cpu/rdrand.c b/kernel/arch/x86/kernel/cpu/rdrand.c
index cfa97ff..c4be620 100644
--- a/kernel/arch/x86/kernel/cpu/rdrand.c
+++ b/kernel/arch/x86/kernel/cpu/rdrand.c
@@ -1,23 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * This file is part of the Linux kernel.
  *
  * Copyright (c) 2011, Intel Corporation
  * Authors: Fenghua Yu <fenghua.yu@intel.com>,
  *          H. Peter Anvin <hpa@linux.intel.com>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
- *
  */
 
 #include <asm/processor.h>
@@ -42,7 +29,8 @@
 #ifdef CONFIG_ARCH_RANDOM
 void x86_init_rdrand(struct cpuinfo_x86 *c)
 {
-	unsigned long tmp;
+	unsigned int changed = 0;
+	unsigned long tmp, prev;
 	int i;
 
 	if (!cpu_has(c, X86_FEATURE_RDRAND))
@@ -55,5 +43,24 @@
 			return;
 		}
 	}
+
+	/*
+	 * Stupid sanity-check whether RDRAND does *actually* generate
+	 * some at least random-looking data.
+	 */
+	prev = tmp;
+	for (i = 0; i < SANITY_CHECK_LOOPS; i++) {
+		if (rdrand_long(&tmp)) {
+			if (prev != tmp)
+				changed++;
+
+			prev = tmp;
+		}
+	}
+
+	if (WARN_ON_ONCE(!changed))
+		pr_emerg(
+"RDRAND gives funky smelling output, might consider not using it by booting with \"nordrand\"");
+
 }
 #endif

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