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}
152