arch/powerpc/boot/addnote.c

   1 /*
   2  * Program to hack in a PT_NOTE program header entry in an ELF file.
   3  * This is needed for OF on RS/6000s to load an image correctly.
   4  * Note that OF needs a program header entry for the note, not an
   5  * ELF section.
   6  *
   7  * Copyright 2000 Paul Mackerras.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation; either version
  12  * 2 of the License, or (at your option) any later version.
  13  *
  14  * Usage: addnote zImage
  15  */
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <fcntl.h>
  19 #include <unistd.h>
  20 #include <string.h>
  21
  22 /* CHRP note section */
  23 static const char arch[] = "PowerPC";
  24
  25 #define N_DESCR 6
  26 unsigned int descr[N_DESCR] = {
  27         0xffffffff,             /* real-mode = true */
  28         0x02000000,             /* real-base, i.e. where we expect OF to be */
  29         0xffffffff,             /* real-size */
  30         0xffffffff,             /* virt-base */
  31         0xffffffff,             /* virt-size */
  32         0x4000,                 /* load-base */
  33 };
  34
  35 /* RPA note section */
  36 static const char rpaname[] = "IBM,RPA-Client-Config";
  37
  38 /*
  39  * Note: setting ignore_my_client_config *should* mean that OF ignores
  40  * all the other fields, but there is a firmware bug which means that
  41  * it looks at the splpar field at least.  So these values need to be
  42  * reasonable.
  43  */
  44 #define N_RPA_DESCR     8
  45 unsigned int rpanote[N_RPA_DESCR] = {
  46         0,                      /* lparaffinity */
  47         64,                     /* min_rmo_size */
  48         0,                      /* min_rmo_percent */
  49         40,                     /* max_pft_size */
  50         1,                      /* splpar */
  51         -1,                     /* min_load */
  52         0,                      /* new_mem_def */
  53         1,                      /* ignore_my_client_config */
  54 };
  55
  56 #define ROUNDUP(len)    (((len) + 3) & ~3)
  57
  58 unsigned char buf[512];
  59
  60 #define GET_16BE(off)   ((buf[off] << 8) + (buf[(off)+1]))
  61 #define GET_32BE(off)   ((GET_16BE(off) << 16) + GET_16BE((off)+2))
  62
  63 #define PUT_16BE(off, v)        (buf[off] = ((v) >> 8) & 0xff, \
  64                                  buf[(off) + 1] = (v) & 0xff)
  65 #define PUT_32BE(off, v)        (PUT_16BE((off), (v) >> 16), \
  66                                  PUT_16BE((off) + 2, (v)))
  67
  68 /* Structure of an ELF file */
  69 #define E_IDENT         0       /* ELF header */
  70 #define E_PHOFF         28
  71 #define E_PHENTSIZE     42
  72 #define E_PHNUM         44
  73 #define E_HSIZE         52      /* size of ELF header */
  74
  75 #define EI_MAGIC        0       /* offsets in E_IDENT area */
  76 #define EI_CLASS        4
  77 #define EI_DATA         5
  78
  79 #define PH_TYPE         0       /* ELF program header */
  80 #define PH_OFFSET       4
  81 #define PH_FILESZ       16
  82 #define PH_HSIZE        32      /* size of program header */
  83
  84 #define PT_NOTE         4       /* Program header type = note */
  85
  86 #define ELFCLASS32      1
  87 #define ELFDATA2MSB     2
  88
  89 unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };
  90
  91 int
  92 main(int ac, char **av)
  93 {
  94         int fd, n, i;
  95         int ph, ps, np;
  96         int nnote, nnote2, ns;
  97
  98         if (ac != 2) {
  99                 fprintf(stderr, "Usage: %s elf-file\n", av[0]);
 100                 exit(1);
 101         }
 102         fd = open(av[1], O_RDWR);
 103         if (fd < 0) {
 104                 perror(av[1]);
 105                 exit(1);
 106         }
 107
 108         nnote = 12 + ROUNDUP(strlen(arch) + 1) + sizeof(descr);
 109         nnote2 = 12 + ROUNDUP(strlen(rpaname) + 1) + sizeof(rpanote);
 110
 111         n = read(fd, buf, sizeof(buf));
 112         if (n < 0) {
 113                 perror("read");
 114                 exit(1);
 115         }
 116
 117         if (n < E_HSIZE || memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0)
 118                 goto notelf;
 119
 120         if (buf[E_IDENT+EI_CLASS] != ELFCLASS32
 121             || buf[E_IDENT+EI_DATA] != ELFDATA2MSB) {
 122                 fprintf(stderr, "%s is not a big-endian 32-bit ELF image\n",
 123                         av[1]);
 124                 exit(1);
 125         }
 126
 127         ph = GET_32BE(E_PHOFF);
 128         ps = GET_16BE(E_PHENTSIZE);
 129         np = GET_16BE(E_PHNUM);
 130         if (ph < E_HSIZE || ps < PH_HSIZE || np < 1)
 131                 goto notelf;
 132         if (ph + (np + 2) * ps + nnote + nnote2 > n)
 133                 goto nospace;
 134
 135         for (i = 0; i < np; ++i) {
 136                 if (GET_32BE(ph + PH_TYPE) == PT_NOTE) {
 137                         fprintf(stderr, "%s already has a note entry\n",
 138                                 av[1]);
 139                         exit(0);
 140                 }
 141                 ph += ps;
 142         }
 143
 144         /* XXX check that the area we want to use is all zeroes */
 145         for (i = 0; i < 2 * ps + nnote + nnote2; ++i)
 146                 if (buf[ph + i] != 0)
 147                         goto nospace;
 148
 149         /* fill in the program header entry */
 150         ns = ph + 2 * ps;
 151         PUT_32BE(ph + PH_TYPE, PT_NOTE);
 152         PUT_32BE(ph + PH_OFFSET, ns);
 153         PUT_32BE(ph + PH_FILESZ, nnote);
 154
 155         /* fill in the note area we point to */
 156         /* XXX we should probably make this a proper section */
 157         PUT_32BE(ns, strlen(arch) + 1);
 158         PUT_32BE(ns + 4, N_DESCR * 4);
 159         PUT_32BE(ns + 8, 0x1275);
 160         strcpy((char *) &buf[ns + 12], arch);
 161         ns += 12 + strlen(arch) + 1;
 162         for (i = 0; i < N_DESCR; ++i, ns += 4)
 163                 PUT_32BE(ns, descr[i]);
 164
 165         /* fill in the second program header entry and the RPA note area */
 166         ph += ps;
 167         PUT_32BE(ph + PH_TYPE, PT_NOTE);
 168         PUT_32BE(ph + PH_OFFSET, ns);
 169         PUT_32BE(ph + PH_FILESZ, nnote2);
 170
 171         /* fill in the note area we point to */
 172         PUT_32BE(ns, strlen(rpaname) + 1);
 173         PUT_32BE(ns + 4, sizeof(rpanote));
 174         PUT_32BE(ns + 8, 0x12759999);
 175         strcpy((char *) &buf[ns + 12], rpaname);
 176         ns += 12 + ROUNDUP(strlen(rpaname) + 1);
 177         for (i = 0; i < N_RPA_DESCR; ++i, ns += 4)
 178                 PUT_32BE(ns, rpanote[i]);
 179
 180         /* Update the number of program headers */
 181         PUT_16BE(E_PHNUM, np + 2);
 182
 183         /* write back */
 184         lseek(fd, (long) 0, SEEK_SET);
 185         i = write(fd, buf, n);
 186         if (i < 0) {
 187                 perror("write");
 188                 exit(1);
 189         }
 190         if (i < n) {
 191                 fprintf(stderr, "%s: write truncated\n", av[1]);
 192                 exit(1);
 193         }
 194
 195         exit(0);
 196
 197  notelf:
 198         fprintf(stderr, "%s does not appear to be an ELF file\n", av[1]);
 199         exit(1);
 200
 201  nospace:
 202         fprintf(stderr, "sorry, I can't find space in %s to put the note\n",
 203                 av[1]);
 204         exit(1);
 205 }