Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 59 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/rdrand.c b/arch/x86/kernel/cpu/rdrand.c
new file mode 100644
index 000000000..cfa97ff67
--- /dev/null
+++ b/arch/x86/kernel/cpu/rdrand.c
@@ -0,0 +1,59 @@
+/*
+ * 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>
+#include <asm/archrandom.h>
+#include <asm/sections.h>
+
+static int __init x86_rdrand_setup(char *s)
+{
+	setup_clear_cpu_cap(X86_FEATURE_RDRAND);
+	setup_clear_cpu_cap(X86_FEATURE_RDSEED);
+	return 1;
+}
+__setup("nordrand", x86_rdrand_setup);
+
+/*
+ * RDRAND has Built-In-Self-Test (BIST) that runs on every invocation.
+ * Run the instruction a few times as a sanity check.
+ * If it fails, it is simple to disable RDRAND here.
+ */
+#define SANITY_CHECK_LOOPS 8
+
+#ifdef CONFIG_ARCH_RANDOM
+void x86_init_rdrand(struct cpuinfo_x86 *c)
+{
+	unsigned long tmp;
+	int i;
+
+	if (!cpu_has(c, X86_FEATURE_RDRAND))
+		return;
+
+	for (i = 0; i < SANITY_CHECK_LOOPS; i++) {
+		if (!rdrand_long(&tmp)) {
+			clear_cpu_cap(c, X86_FEATURE_RDRAND);
+			pr_warn_once("rdrand: disabled\n");
+			return;
+		}
+	}
+}
+#endif