arch/sparc/boot/piggyback.c

   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
  42 static int is64bit = 0;
  43
  44 /* align to power-of-two size */
  45 static 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 */
  54 static unsigned short ld2(char *p)
  55 {
  56         return (p[0] << 8) | p[1];
  57 }
  58
  59 /* save 4 bytes as big endian */
  60 static 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
  68 static void die(const char *str)
  69 {
  70         perror(str);
  71         exit(1);
  72 }
  73
  74 static 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
  82 static 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
  91 static 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  */
 111 static 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  */
 146 static 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
 184 int 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 }