1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Makes a tree bootable image for IBM Evaluation boards.
  4 * Basically, just take a zImage, skip the ELF header, and stuff
  5 * a 32 byte header on the front.
  6 *
  7 * We use htonl, which is a network macro, to make sure we're doing
  8 * The Right Thing on an LE machine.  It's non-obvious, but it should
  9 * work on anything BSD'ish.
 10 */
 11
 12#include <fcntl.h>
 13#include <stdio.h>
 14#include <stdlib.h>
 15#include <string.h>
 16#include <sys/stat.h>
 17#include <unistd.h>
 18#include <netinet/in.h>
 19#ifdef __sun__
 20#include <inttypes.h>
 21#else
 22#include <stdint.h>
 23#endif
 24
 25/* This gets tacked on the front of the image.  There are also a few
 26 * bytes allocated after the _start label used by the boot rom (see
 27 * head.S for details).
 28 */
 29typedef struct boot_block {
 30	uint32_t bb_magic;		/* 0x0052504F */
 31	uint32_t bb_dest;		/* Target address of the image */
 32	uint32_t bb_num_512blocks;	/* Size, rounded-up, in 512 byte blks */
 33	uint32_t bb_debug_flag;	/* Run debugger or image after load */
 34	uint32_t bb_entry_point;	/* The image address to start */
 35	uint32_t bb_checksum;	/* 32 bit checksum including header */
 36	uint32_t reserved[2];
 37} boot_block_t;
 38
 39#define IMGBLK	512
 40unsigned int	tmpbuf[IMGBLK / sizeof(unsigned int)];
 41
 42int main(int argc, char *argv[])
 43{
 44	int	in_fd, out_fd;
 45	int	nblks, i;
 46	unsigned int	cksum, *cp;
 47	struct	stat	st;
 48	boot_block_t	bt;
 49
 50	if (argc < 5) {
 51		fprintf(stderr, "usage: %s <zImage-file> <boot-image> <load address> <entry point>\n",argv[0]);
 52		exit(1);
 53	}
 54
 55	if (stat(argv[1], &st) < 0) {
 56		perror("stat");
 57		exit(2);
 58	}
 59
 60	nblks = (st.st_size + IMGBLK) / IMGBLK;
 61
 62	bt.bb_magic = htonl(0x0052504F);
 63
 64	/* If we have the optional entry point parameter, use it */
 65	bt.bb_dest = htonl(strtoul(argv[3], NULL, 0));
 66	bt.bb_entry_point = htonl(strtoul(argv[4], NULL, 0));
 67
 68	/* We know these from the linker command.
 69	 * ...and then move it up into memory a little more so the
 70	 * relocation can happen.
 71	 */
 72	bt.bb_num_512blocks = htonl(nblks);
 73	bt.bb_debug_flag = 0;
 74
 75	bt.bb_checksum = 0;
 76
 77	/* To be neat and tidy :-).
 78	*/
 79	bt.reserved[0] = 0;
 80	bt.reserved[1] = 0;
 81
 82	if ((in_fd = open(argv[1], O_RDONLY)) < 0) {
 83		perror("zImage open");
 84		exit(3);
 85	}
 86
 87	if ((out_fd = open(argv[2], (O_RDWR | O_CREAT | O_TRUNC), 0666)) < 0) {
 88		perror("bootfile open");
 89		exit(3);
 90	}
 91
 92	cksum = 0;
 93	cp = (void *)&bt;
 94	for (i = 0; i < sizeof(bt) / sizeof(unsigned int); i++)
 95		cksum += *cp++;
 96
 97	/* Assume zImage is an ELF file, and skip the 64K header.
 98	*/
 99	if (read(in_fd, tmpbuf, sizeof(tmpbuf)) != sizeof(tmpbuf)) {
100		fprintf(stderr, "%s is too small to be an ELF image\n",
101				argv[1]);
102		exit(4);
103	}
104
105	if (tmpbuf[0] != htonl(0x7f454c46)) {
106		fprintf(stderr, "%s is not an ELF image\n", argv[1]);
107		exit(4);
108	}
109
110	if (lseek(in_fd, (64 * 1024), SEEK_SET) < 0) {
111		fprintf(stderr, "%s failed to seek in ELF image\n", argv[1]);
112		exit(4);
113	}
114
115	nblks -= (64 * 1024) / IMGBLK;
116
117	/* And away we go......
118	*/
119	if (write(out_fd, &bt, sizeof(bt)) != sizeof(bt)) {
120		perror("boot-image write");
121		exit(5);
122	}
123
124	while (nblks-- > 0) {
125		if (read(in_fd, tmpbuf, sizeof(tmpbuf)) < 0) {
126			perror("zImage read");
127			exit(5);
128		}
129		cp = tmpbuf;
130		for (i = 0; i < sizeof(tmpbuf) / sizeof(unsigned int); i++)
131			cksum += *cp++;
132		if (write(out_fd, tmpbuf, sizeof(tmpbuf)) != sizeof(tmpbuf)) {
133			perror("boot-image write");
134			exit(5);
135		}
136	}
137
138	/* rewrite the header with the computed checksum.
139	*/
140	bt.bb_checksum = htonl(cksum);
141	if (lseek(out_fd, 0, SEEK_SET) < 0) {
142		perror("rewrite seek");
143		exit(1);
144	}
145	if (write(out_fd, &bt, sizeof(bt)) != sizeof(bt)) {
146		perror("boot-image rewrite");
147		exit(1);
148	}
149
150	exit(0);
151}