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