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1/*
2 Simple utility to make a single-image install kernel with initial ramdisk
3 for Sparc tftpbooting without need to set up nfs.
4
5 Copyright (C) 1996,1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
6 Pete Zaitcev <zaitcev@yahoo.com> endian fixes for cross-compiles, 2000.
7 Copyright (C) 2011 Sam Ravnborg <sam@ravnborg.org>
8
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
13
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
22
23#include <dirent.h>
24#include <stdlib.h>
25#include <string.h>
26#include <unistd.h>
27#include <ctype.h>
28#include <errno.h>
29#include <fcntl.h>
30#include <stdio.h>
31
32#include <sys/types.h>
33#include <sys/stat.h>
34
35/*
36 * Note: run this on an a.out kernel (use elftoaout for it),
37 * as PROM looks for a.out image only.
38 */
39
40#define AOUT_TEXT_OFFSET 32
41
42static int is64bit = 0;
43
44/* align to power-of-two size */
45static int align(int n)
46{
47 if (is64bit)
48 return (n + 0x1fff) & ~0x1fff;
49 else
50 return (n + 0xfff) & ~0xfff;
51}
52
53/* read two bytes as big endian */
54static unsigned short ld2(char *p)
55{
56 return (p[0] << 8) | p[1];
57}
58
59/* save 4 bytes as big endian */
60static void st4(char *p, unsigned int x)
61{
62 p[0] = x >> 24;
63 p[1] = x >> 16;
64 p[2] = x >> 8;
65 p[3] = x;
66}
67
68static void die(const char *str)
69{
70 perror(str);
71 exit(1);
72}
73
74static void usage(void)
75{
76 /* fs_img.gz is an image of initial ramdisk. */
77 fprintf(stderr, "Usage: piggyback bits vmlinux.aout System.map fs_img.gz\n");
78 fprintf(stderr, "\tKernel image will be modified in place.\n");
79 exit(1);
80}
81
82static int start_line(const char *line)
83{
84 if (strcmp(line + 8, " T _start\n") == 0)
85 return 1;
86 else if (strcmp(line + 16, " T _start\n") == 0)
87 return 1;
88 return 0;
89}
90
91static int end_line(const char *line)
92{
93 if (strcmp(line + 8, " A _end\n") == 0)
94 return 1;
95 else if (strcmp (line + 16, " A _end\n") == 0)
96 return 1;
97 return 0;
98}
99
100/*
101 * Find address for start and end in System.map.
102 * The file looks like this:
103 * f0004000 T _start
104 * f0379f79 A _end
105 * 1234567890123456
106 * ^coloumn 1
107 * There is support for 64 bit addresses too.
108 *
109 * Return 0 if either start or end is not found
110 */
111static int get_start_end(const char *filename, unsigned int *start,
112 unsigned int *end)
113{
114 FILE *map;
115 char buffer[1024];
116
117 *start = 0;
118 *end = 0;
119 map = fopen(filename, "r");
120 if (!map)
121 die(filename);
122 while (fgets(buffer, 1024, map)) {
123 if (start_line(buffer))
124 *start = strtoul(buffer, NULL, 16);
125 else if (end_line(buffer))
126 *end = strtoul(buffer, NULL, 16);
127 }
128 fclose (map);
129
130 if (*start == 0 || *end == 0)
131 return 0;
132
133 return 1;
134}
135
136#define LOOKBACK (128 * 4)
137#define BUFSIZE 1024
138/*
139 * Find the HdrS entry from head_32/head_64.
140 * We check if it is at the beginning of the file (sparc64 case)
141 * and if not we search for it.
142 * When we search do so in steps of 4 as HdrS is on a 4-byte aligned
143 * address (it is on same alignment as sparc instructions)
144 * Return the offset to the HdrS entry (as off_t)
145 */
146static off_t get_hdrs_offset(int kernelfd, const char *filename)
147{
148 char buffer[BUFSIZE];
149 off_t offset;
150 int i;
151
152 if (lseek(kernelfd, 0, SEEK_SET) < 0)
153 die("lseek");
154 if (read(kernelfd, buffer, BUFSIZE) != BUFSIZE)
155 die(filename);
156
157 if (buffer[40] == 'H' && buffer[41] == 'd' &&
158 buffer[42] == 'r' && buffer[43] == 'S') {
159 return 40;
160 } else {
161 /* Find the gokernel label */
162 /* Decode offset from branch instruction */
163 offset = ld2(buffer + AOUT_TEXT_OFFSET + 2) << 2;
164 /* Go back 512 bytes so we do not miss HdrS */
165 offset -= LOOKBACK;
166 /* skip a.out header */
167 offset += AOUT_TEXT_OFFSET;
168 if (lseek(kernelfd, offset, SEEK_SET) < 0)
169 die("lseek");
170 if (read(kernelfd, buffer, BUFSIZE) != BUFSIZE)
171 die(filename);
172
173 for (i = 0; i < LOOKBACK; i += 4) {
174 if (buffer[i + 0] == 'H' && buffer[i + 1] == 'd' &&
175 buffer[i + 2] == 'r' && buffer[i + 3] == 'S') {
176 return offset + i;
177 }
178 }
179 }
180 fprintf (stderr, "Couldn't find headers signature in %s\n", filename);
181 exit(1);
182}
183
184int main(int argc,char **argv)
185{
186 static char aout_magic[] = { 0x01, 0x03, 0x01, 0x07 };
187 char buffer[1024];
188 unsigned int i, start, end;
189 off_t offset;
190 struct stat s;
191 int image, tail;
192
193 if (argc != 5)
194 usage();
195 if (strcmp(argv[1], "64") == 0)
196 is64bit = 1;
197 if (stat (argv[4], &s) < 0)
198 die(argv[4]);
199
200 if (!get_start_end(argv[3], &start, &end)) {
201 fprintf(stderr, "Could not determine start and end from %s\n",
202 argv[3]);
203 exit(1);
204 }
205 if ((image = open(argv[2], O_RDWR)) < 0)
206 die(argv[2]);
207 if (read(image, buffer, 512) != 512)
208 die(argv[2]);
209 if (memcmp(buffer, aout_magic, 4) != 0) {
210 fprintf (stderr, "Not a.out. Don't blame me.\n");
211 exit(1);
212 }
213 /*
214 * We need to fill in values for
215 * sparc_ramdisk_image + sparc_ramdisk_size
216 * To locate these symbols search for the "HdrS" text which appear
217 * in the image a little before the gokernel symbol.
218 * See definition of these in init_32.S
219 */
220
221 offset = get_hdrs_offset(image, argv[2]);
222 /* skip HdrS + LINUX_VERSION_CODE + HdrS version */
223 offset += 10;
224
225 if (lseek(image, offset, 0) < 0)
226 die("lseek");
227
228 /*
229 * root_flags = 0
230 * root_dev = 1 (RAMDISK_MAJOR)
231 * ram_flags = 0
232 * sparc_ramdisk_image = "PAGE aligned address after _end")
233 * sparc_ramdisk_size = size of image
234 */
235 st4(buffer, 0);
236 st4(buffer + 4, 0x01000000);
237 st4(buffer + 8, align(end + 32));
238 st4(buffer + 12, s.st_size);
239
240 if (write(image, buffer + 2, 14) != 14)
241 die(argv[2]);
242
243 /* For sparc64 update a_text and clear a_data + a_bss */
244 if (is64bit)
245 {
246 if (lseek(image, 4, 0) < 0)
247 die("lseek");
248 /* a_text */
249 st4(buffer, align(end + 32 + 8191) - (start & ~0x3fffffUL) +
250 s.st_size);
251 /* a_data */
252 st4(buffer + 4, 0);
253 /* a_bss */
254 st4(buffer + 8, 0);
255 if (write(image, buffer, 12) != 12)
256 die(argv[2]);
257 }
258
259 /* seek page aligned boundary in the image file and add boot image */
260 if (lseek(image, AOUT_TEXT_OFFSET - start + align(end + 32), 0) < 0)
261 die("lseek");
262 if ((tail = open(argv[4], O_RDONLY)) < 0)
263 die(argv[4]);
264 while ((i = read(tail, buffer, 1024)) > 0)
265 if (write(image, buffer, i) != i)
266 die(argv[2]);
267 if (close(image) < 0)
268 die("close");
269 if (close(tail) < 0)
270 die("close");
271 return 0;
272}