1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 Simple utility to make a single-image install kernel with initial ramdisk
4 for Sparc tftpbooting without need to set up nfs.
5
6 Copyright (C) 1996,1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
7 Pete Zaitcev <zaitcev@yahoo.com> endian fixes for cross-compiles, 2000.
8 Copyright (C) 2011 Sam Ravnborg <sam@ravnborg.org>
9
10 */
11
12 #include <dirent.h>
13 #include <stdlib.h>
14 #include <string.h>
15 #include <unistd.h>
16 #include <ctype.h>
17 #include <errno.h>
18 #include <fcntl.h>
19 #include <stdio.h>
20
21 #include <sys/types.h>
22 #include <sys/stat.h>
23
24 /*
25 * Note: run this on an a.out kernel (use elftoaout for it),
26 * as PROM looks for a.out image only.
27 */
28
29 #define AOUT_TEXT_OFFSET 32
30
31 static int is64bit = 0;
32
33 /* align to power-of-two size */
34 static int align(int n)
35 {
36 if (is64bit)
37 return (n + 0x1fff) & ~0x1fff;
38 else
39 return (n + 0xfff) & ~0xfff;
40 }
41
42 /* read two bytes as big endian */
43 static unsigned short ld2(char *p)
44 {
45 return (p[0] << 8) | p[1];
46 }
47
48 /* save 4 bytes as big endian */
49 static void st4(char *p, unsigned int x)
50 {
51 p[0] = x >> 24;
52 p[1] = x >> 16;
53 p[2] = x >> 8;
54 p[3] = x;
55 }
56
57 static void die(const char *str)
58 {
59 perror(str);
60 exit(1);
61 }
62
63 static void usage(void)
64 {
65 /* fs_img.gz is an image of initial ramdisk. */
66 fprintf(stderr, "Usage: piggyback bits vmlinux.aout System.map fs_img.gz\n");
67 fprintf(stderr, "\tKernel image will be modified in place.\n");
68 exit(1);
69 }
70
71 static int start_line(const char *line)
72 {
73 if (strcmp(line + 10, " _start\n") == 0)
74 return 1;
75 else if (strcmp(line + 18, " _start\n") == 0)
76 return 1;
77 return 0;
78 }
79
80 static int end_line(const char *line)
81 {
82 if (strcmp(line + 10, " _end\n") == 0)
83 return 1;
84 else if (strcmp (line + 18, " _end\n") == 0)
85 return 1;
86 return 0;
87 }
88
89 /*
90 * Find address for start and end in System.map.
91 * The file looks like this:
92 * f0004000 ... _start
93 * f0379f79 ... _end
94 * 1234567890123456
95 * ^coloumn 1
96 * There is support for 64 bit addresses too.
97 *
98 * Return 0 if either start or end is not found
99 */
100 static int get_start_end(const char *filename, unsigned int *start,
101 unsigned int *end)
102 {
103 FILE *map;
104 char buffer[1024];
105
106 *start = 0;
107 *end = 0;
108 map = fopen(filename, "r");
109 if (!map)
110 die(filename);
111 while (fgets(buffer, 1024, map)) {
112 if (start_line(buffer))
113 *start = strtoul(buffer, NULL, 16);
114 else if (end_line(buffer))
115 *end = strtoul(buffer, NULL, 16);
116 }
117 fclose (map);
118
119 if (*start == 0 || *end == 0)
120 return 0;
121
122 return 1;
123 }
124
125 #define LOOKBACK (128 * 4)
126 #define BUFSIZE 1024
127 /*
128 * Find the HdrS entry from head_32/head_64.
129 * We check if it is at the beginning of the file (sparc64 case)
130 * and if not we search for it.
131 * When we search do so in steps of 4 as HdrS is on a 4-byte aligned
132 * address (it is on same alignment as sparc instructions)
133 * Return the offset to the HdrS entry (as off_t)
134 */
135 static off_t get_hdrs_offset(int kernelfd, const char *filename)
136 {
137 char buffer[BUFSIZE];
138 off_t offset;
139 int i;
140
141 if (lseek(kernelfd, 0, SEEK_SET) < 0)
142 die("lseek");
143 if (read(kernelfd, buffer, BUFSIZE) != BUFSIZE)
144 die(filename);
145
146 if (buffer[40] == 'H' && buffer[41] == 'd' &&
147 buffer[42] == 'r' && buffer[43] == 'S') {
148 return 40;
149 } else {
150 /* Find the gokernel label */
151 /* Decode offset from branch instruction */
152 offset = ld2(buffer + AOUT_TEXT_OFFSET + 2) << 2;
153 /* Go back 512 bytes so we do not miss HdrS */
154 offset -= LOOKBACK;
155 /* skip a.out header */
156 offset += AOUT_TEXT_OFFSET;
157 if (offset < 0) {
158 errno = -EINVAL;
159 die("Calculated a negative offset, probably elftoaout generated an invalid image. Did you use a recent elftoaout ?");
160 }
161 if (lseek(kernelfd, offset, SEEK_SET) < 0)
162 die("lseek");
163 if (read(kernelfd, buffer, BUFSIZE) != BUFSIZE)
164 die(filename);
165
166 for (i = 0; i < LOOKBACK; i += 4) {
167 if (buffer[i + 0] == 'H' && buffer[i + 1] == 'd' &&
168 buffer[i + 2] == 'r' && buffer[i + 3] == 'S') {
169 return offset + i;
170 }
171 }
172 }
173 fprintf (stderr, "Couldn't find headers signature in %s\n", filename);
174 exit(1);
175 }
176
177 int main(int argc,char **argv)
178 {
179 static char aout_magic[] = { 0x01, 0x03, 0x01, 0x07 };
180 char buffer[1024];
181 unsigned int i, start, end;
182 off_t offset;
183 struct stat s;
184 int image, tail;
185
186 if (argc != 5)
187 usage();
188 if (strcmp(argv[1], "64") == 0)
189 is64bit = 1;
190 if (stat (argv[4], &s) < 0)
191 die(argv[4]);
192
193 if (!get_start_end(argv[3], &start, &end)) {
194 fprintf(stderr, "Could not determine start and end from %s\n",
195 argv[3]);
196 exit(1);
197 }
198 if ((image = open(argv[2], O_RDWR)) < 0)
199 die(argv[2]);
200 if (read(image, buffer, 512) != 512)
201 die(argv[2]);
202 if (memcmp(buffer, aout_magic, 4) != 0) {
203 fprintf (stderr, "Not a.out. Don't blame me.\n");
204 exit(1);
205 }
206 /*
207 * We need to fill in values for
208 * sparc_ramdisk_image + sparc_ramdisk_size
209 * To locate these symbols search for the "HdrS" text which appear
210 * in the image a little before the gokernel symbol.
211 * See definition of these in init_32.S
212 */
213
214 offset = get_hdrs_offset(image, argv[2]);
215 /* skip HdrS + LINUX_VERSION_CODE + HdrS version */
216 offset += 10;
217
218 if (lseek(image, offset, 0) < 0)
219 die("lseek");
220
221 /*
222 * root_flags = 0
223 * root_dev = 1 (RAMDISK_MAJOR)
224 * ram_flags = 0
225 * sparc_ramdisk_image = "PAGE aligned address after _end")
226 * sparc_ramdisk_size = size of image
227 */
228 st4(buffer, 0);
229 st4(buffer + 4, 0x01000000);
230 st4(buffer + 8, align(end + 32));
231 st4(buffer + 12, s.st_size);
232
233 if (write(image, buffer + 2, 14) != 14)
234 die(argv[2]);
235
236 /* For sparc64 update a_text and clear a_data + a_bss */
237 if (is64bit)
238 {
239 if (lseek(image, 4, 0) < 0)
240 die("lseek");
241 /* a_text */
242 st4(buffer, align(end + 32 + 8191) - (start & ~0x3fffffUL) +
243 s.st_size);
244 /* a_data */
245 st4(buffer + 4, 0);
246 /* a_bss */
247 st4(buffer + 8, 0);
248 if (write(image, buffer, 12) != 12)
249 die(argv[2]);
250 }
251
252 /* seek page aligned boundary in the image file and add boot image */
253 if (lseek(image, AOUT_TEXT_OFFSET - start + align(end + 32), 0) < 0)
254 die("lseek");
255 if ((tail = open(argv[4], O_RDONLY)) < 0)
256 die(argv[4]);
257 while ((i = read(tail, buffer, 1024)) > 0)
258 if (write(image, buffer, i) != i)
259 die(argv[2]);
260 if (close(image) < 0)
261 die("close");
262 if (close(tail) < 0)
263 die("close");
264 return 0;
265 }
266
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.