AMD Steppe Eagle: Add 32-bit Fletcher's Checksum computation

The AMD Platform Security Processor (PSP) requires a Fletcher's
Checksum at the end of the PSP directory.  This code implements
a Fletcher's Checksum by reading bytes from stdin and writes the
bytes back to stdout with a checksum inserted into the byte stream
at the appropriate offset.

This utility is used on PSP binaries during coreboot build.

Include a runtime debug option such that the command:

	fletcher --print <file.bin >file_with_cksum.bin

will print out the computed checksum value for debugging.  The
compile-time debug option is retained that allows -DDEBUG to
be added to the compilation line.  This option has the same
effect as "--print".

Change-Id: I506a479d8204ca4f8267d53aa152ac4b473dbc75
Signed-off-by: Bruce Griffith <Bruce.Griffith@se-eng.com>
Reviewed-on: http://review.coreboot.org/6676
Reviewed-by: WANG Siyuan <wangsiyuanbuaa@gmail.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Zheng Bao <zheng.bao@amd.com>

1 files changed, 128 insertions, 0 deletions

diff --git a/util/fletcher/fletcher.c b/util/fletcher/fletcher.c
new file mode 100644
index 0000000000..3147d50376
--- /dev/null
+++ b/util/fletcher/fletcher.c
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 1998-2006 The TCPDUMP project
+ *               2014      Sage Electronic Engineering, LLC
+ * All Rights Reserved
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that: (1) source code
+ * distributions retain the above copyright notice and this paragraph
+ * in its entirety, and (2) distributions including binary code include
+ * the above copyright notice and this paragraph in its entirety in
+ * the documentation or other materials provided with the distribution.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND
+ * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
+ * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE.
+ *
+ * Original code by Hannes Gredler <hannes@juniper.net>
+ * Rewritten for Fletcher32 by Bruce Griffith <Bruce.Griffith@se-eng.com>
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <string.h>
+
+#define MAX_PSP_DIRECTORY_SIZE 512
+
+typedef unsigned int uint32_t;
+typedef unsigned char uint8_t;
+typedef unsigned short uint16_t;
+
+/*
+ * Creates the OSI Fletcher checksum. See 8473-1, Appendix C, section C.3.
+ * The checksum field of the passed PDU does not need to be reset to zero.
+ *
+ * The "Fletcher Checksum" was proposed in a paper by John G. Fletcher of
+ * Lawrence Livermore Labs.  The Fletcher Checksum was proposed as an
+ * alternative to cyclical redundancy checks because it provides error-
+ * detection properties similar to cyclical redundancy checks but at the
+ * cost of a simple summation technique.  Its characteristics were first
+ * published in IEEE Transactions on Communications in January 1982.  One
+ * version has been adopted by ISO for use in the class-4 transport layer
+ * of the network protocol.
+ *
+ * This program expects:
+ *    stdin:    The input file to compute a checksum for.  The input file
+ *              not be longer than 256 bytes.
+ *    stdout:   Copied from the input file with the Fletcher's Checksum
+ *              inserted 8 bytes after the beginning of the file.
+ *    stderr:   Used to print out error messages.
+ */
+
+uint32_t fletcher32 (const uint16_t *pptr, int length)
+{
+
+	uint32_t c0;
+	uint32_t c1;
+	uint32_t checksum;
+	int index;
+
+	c0 = 0xFFFF;
+	c1 = 0xFFFF;
+
+	for (index = 0; index < length; index++) {
+		/*
+		* Ignore the contents of the checksum field.
+		*/
+		c0 += *(pptr++);
+		c1 += c0;
+		if ((index % 360) == 0) {
+			c0 = (c0 & 0xFFFF) + (c0 >> 16);	// Sum0 modulo 65535 + the overflow
+			c1 = (c1 & 0xFFFF) + (c1 >> 16);	// Sum1 modulo 65535 + the overflow
+		}
+
+	}
+
+	c0 = (c0 & 0xFFFF) + (c0 >> 16);	// Sum0 modulo 65535 + the overflow
+	c1 = (c1 & 0xFFFF) + (c1 >> 16);	// Sum1 modulo 65535 + the overflow
+	checksum = (c1 << 16) | c0;
+
+	return checksum;
+}
+
+int main(int argc, char **argv)
+{
+	uint32_t checksum = 0xFFFFFFFF;
+	struct stat filestat = {};
+	int retcode = EINVAL;
+	size_t filesize = 0;
+	char debugoption[] = "--print";
+
+	uint16_t buffer[MAX_PSP_DIRECTORY_SIZE / sizeof(uint16_t)];
+
+	retcode = fstat(fileno(stdin), &filestat);
+	filesize = filestat.st_size;
+	if (retcode < 0) {
+		perror("FLETCHER32");
+		return errno;
+	} else if (!((12 < filesize) && (filesize <= sizeof(buffer)))) {
+		fprintf(stderr, "FLETCHER32: input file is not valid for this program.\n");
+		return EINVAL;
+	}
+	retcode = read(fileno(stdin), (void *)buffer, filesize);
+	if (retcode < 0) {
+		perror("FLETCHER32");
+		return errno;
+	}
+
+	checksum = fletcher32(&buffer[2], filesize/2 - 2);
+	*((uint32_t *)& buffer[2]) = checksum;
+#ifndef DEBUG
+	if ((argc == 2) && !strncmp(argv[1], debugoption, sizeof(debugoption+1))) {
+#endif
+		fprintf(stderr, "Fletcher's Checksum: %x\n", checksum);
+#ifndef DEBUG
+	}
+#endif
+
+	retcode = write(fileno(stdout), buffer, filesize);
+	if (retcode < 0) {
+		perror("FLETCHER32");
+		return errno;
+	}
+
+	return 0;
+}