Reorganise the entropy device so that high-yield entropy sources

can more easily be used INSTEAD OF the hard-working Yarrow.
The only hardware source used at this point is the one inside
the VIA C3 Nehemiah (Stepping 3 and above) CPU. More sources will
be added in due course. Contributions welcome!

1 files changed, 66 insertions, 0 deletions

diff --git a/sys/dev/random/nehemiah.c b/sys/dev/random/nehemiah.c
new file mode 100644
index 0000000..e496828
--- /dev/null
+++ b/sys/dev/random/nehemiah.c
@@ -0,0 +1,66 @@
+/*-
+ * Copyright (c) 2004 Mark R V Murray
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer
+ *    in this position and unchanged.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/selinfo.h>
+
+#include <dev/random/randomdev.h>
+
+static int random_nehemiah_read(void *, int);
+
+struct random_systat random_nehemiah = {
+	.ident = "Hardware, VIA Nehemiah",
+	.init = (random_init_func_t *)random_null_func,
+	.deinit = (random_deinit_func_t *)random_null_func,
+	.read = random_nehemiah_read,
+	.write = (random_write_func_t *)random_null_func,
+	.reseed = (random_reseed_func_t *)random_null_func,
+	.seeded = 1,
+};
+
+/* ARGSUSED */
+static int
+random_nehemiah_read(void *buf, int c)
+{
+#if (defined(__GNUC__) || defined(__INTEL_COMPILER)) && defined(__i386__)
+	int count = c;
+	int rate = 0;
+
+	/* VIA C3 Nehemiah "rep; xstore" */
+	__asm __volatile("rep; .byte 0x0f, 0xa7, 0xc0"
+				: "+D" (buf), "+c" (count), "=d" (rate)
+				:
+				: "memory");
+#endif
+	return (c);
+}