Add a tool to split Intel microcode into one file per Platform Id

Intel now releases microcode updates in files named after
<family>-<model>-<stepping>.  In some cases a single file may include
microcode for multiple Platform Ids for the same family, model, and
stepping.  Our current microcode update tooling (/usr/sbin/cpucontrol)
only processes the first microcode update in the file.

This tool splits combined files into individual files with one microcode
update each, named as
<family>-<model>-<stepping>.<platform_id_mask>.

Adding this to tools/ for experimentation and testing.  In the future
we'll want to have cpucontrol or other tooling work directly with the
Intel-provided microcode files.

Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D15433

tools/tools/intel-ucode-split/Makefile

@@ -0,0 +1,6 @@
+# $FreeBSD$
+
+PROG=	intel-ucode-split
+MAN=
+
+.include <bsd.prog.mk>

tools/tools/intel-ucode-split/intel-ucode-split.c

@@ -0,0 +1,169 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (C) 2018 The FreeBSD Foundation.
+ *
+ * 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.
+ * 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <err.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static const size_t bufsize = 65536;
+
+/* SDM vol 3 9.11.1 Intel microcode header. */
+struct microcode_update_header {
+	uint32_t header_version;
+	uint32_t update_revision;
+	uint32_t date;			/* BCD mmddyyyy */
+	uint32_t processor_signature;
+	uint32_t checksum;		/* Over update data and header */
+	uint32_t loader_revision;
+	uint32_t processor_flags;
+	uint32_t data_size;
+	uint32_t total_size;
+	uint32_t reserved[3];
+};
+
+/*
+ * SDM vol 2A CPUID EAX = 01h Returns Model, Family, Stepping Information.
+ * 9 chars including the NUL terminator will be written to buf.
+ */
+
+static char *
+format_signature(char *buf, uint32_t signature)
+{
+	unsigned family, model, stepping;
+
+	family = (signature & 0xf00) >> 8;
+	model = (signature & 0xf0) >> 4;
+	stepping = signature & 0xf;
+	if (family == 0x06 || family == 0x0f)
+		model += (signature & 0xf0000) >> 12;
+	if (family == 0x0f)
+		family += (signature & 0xff00000) >> 20;
+	sprintf(buf, "%02x-%02x-%02x", family, model, stepping);
+	return (buf);
+}
+
+static void
+dump_header(const struct microcode_update_header *hdr)
+{
+	char buf[16];
+
+	printf("version\t\t0x%x\n", hdr->header_version);
+	printf("revision\t0x%x\n", hdr->update_revision);
+	printf("date\t\t0x%x\t%04x-%02x-%02x\n", hdr->date,
+	    hdr->date & 0xffff, (hdr->date & 0xff000000) >> 24,
+	    (hdr->date & 0xff0000) >> 16);
+	printf("signature\t0x%x\t\t%s\n", hdr->processor_signature,
+	    format_signature(buf, hdr->processor_signature));
+	printf("checksum\t0x%x\n", hdr->checksum);
+	printf("loader revision\t0x%x\n", hdr->loader_revision);
+	printf("processor flags\t0x%x\n", hdr->processor_flags);
+	printf("datasize\t0x%x\t\t0x%x\n", hdr->data_size,
+	    hdr->data_size != 0 ? hdr->data_size : 2000);
+	printf("size\t\t0x%x\t\t0x%x\n", hdr->total_size,
+	    hdr->total_size != 0 ? hdr->total_size : 2048);
+}
+
+static void
+usage(void)
+{
+
+	printf("ucode-split microcode_file\n");
+	exit(1);
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct microcode_update_header hdr;
+	char output_file[128];
+	char *buf;
+	size_t len, resid;
+	ssize_t rv;
+	int ifd, ofd;
+
+	if (argc != 2)
+		usage();
+
+	ifd = open(argv[1], O_RDONLY);
+	if (ifd < 0)
+		err(1, "open");
+
+	buf = malloc(bufsize);
+	if (buf == NULL)
+		err(1, "malloc");
+
+	for (;;) {
+		/* Read header. */
+		rv = read(ifd, &hdr, sizeof(hdr));
+		if (rv < 0) {
+			err(1, "read");
+		} else if (rv == 0) {
+			break;
+		} else if (rv < (ssize_t)sizeof(hdr)) {
+			errx(1, "invalid microcode header");
+		}
+
+		dump_header(&hdr);
+
+		format_signature(output_file, hdr.processor_signature);
+		sprintf(output_file + strlen(output_file), ".%02x",
+		    hdr.processor_flags & 0xff);
+		ofd = open(output_file, O_WRONLY | O_CREAT | O_TRUNC, 0600);
+		if (ofd < 0)
+			err(1, "open");
+
+		/* Write header. */
+		rv = write(ofd, &hdr, sizeof(hdr));
+		if (rv < (ssize_t)sizeof(hdr))
+			err(1, "write");
+
+		/* Copy data. */
+		resid = (hdr.total_size != 0 ? hdr.total_size : 2048) -
+		    sizeof(hdr);
+		if (resid > 1 << 24) /* Arbitrary chosen maximum size. */
+			errx(1, "header total_size too large");
+		while (resid > 0) {
+			len = resid < bufsize ? resid : bufsize;
+			rv = read(ifd, buf, len);
+			if (rv < 0)
+				err(1, "read");
+			else if (rv < (ssize_t)len)
+				errx(1, "truncated microcode data");
+			if (write(ofd, buf, len) < (ssize_t)len)
+				err(1, "write");
+			resid -= len;
+		}
+		printf("written to %s\n\n", output_file);
+		close(ofd);
+	}
+}