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 */
29 typedef 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
40 unsigned int tmpbuf[IMGBLK / sizeof(unsigned int)];
41
42 int 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
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