LXR linux-old/arch/ppc64/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
  22char arch[] = "PowerPC";
  23
  24#define N_DESCR 6
  25unsigned int descr[N_DESCR] = {
  26        0xffffffff,             /* real-mode = true */
  27        0x00c00000,             /* real-base, i.e. where we expect OF to be */
  28        0xffffffff,             /* real-size */
  29        0xffffffff,             /* virt-base */
  30        0xffffffff,             /* virt-size */
  31        0x4000,                 /* load-base */
  32};
  33
  34unsigned char buf[512];
  35
  36#define GET_16BE(off)   ((buf[off] << 8) + (buf[(off)+1]))
  37#define GET_32BE(off)   ((GET_16BE(off) << 16) + GET_16BE((off)+2))
  38
  39#define PUT_16BE(off, v)        (buf[off] = ((v) >> 8) & 0xff, \
  40                                 buf[(off) + 1] = (v) & 0xff)
  41#define PUT_32BE(off, v)        (PUT_16BE((off), (v) >> 16), \
  42                                 PUT_16BE((off) + 2, (v)))
  43
  44/* Structure of an ELF file */
  45#define E_IDENT         0       /* ELF header */
  46#define E_PHOFF         28
  47#define E_PHENTSIZE     42
  48#define E_PHNUM         44
  49#define E_HSIZE         52      /* size of ELF header */
  50
  51#define EI_MAGIC        0       /* offsets in E_IDENT area */
  52#define EI_CLASS        4
  53#define EI_DATA         5
  54
  55#define PH_TYPE         0       /* ELF program header */
  56#define PH_OFFSET       4
  57#define PH_FILESZ       16
  58#define PH_HSIZE        32      /* size of program header */
  59
  60#define PT_NOTE         4       /* Program header type = note */
  61
  62#define ELFCLASS32      1
  63#define ELFDATA2MSB     2
  64
  65unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };
  66
  67int
  68main(int ac, char **av)
  69{
  70        int fd, n, i;
  71        int ph, ps, np;
  72        int nnote, ns;
  73
  74        if (ac != 2) {
  75                fprintf(stderr, "Usage: %s elf-file\n", av[0]);
  76                exit(1);
  77        }
  78        fd = open(av[1], O_RDWR);
  79        if (fd < 0) {
  80                perror(av[1]);
  81                exit(1);
  82        }
  83
  84        nnote = strlen(arch) + 1 + (N_DESCR + 3) * 4;
  85
  86        n = read(fd, buf, sizeof(buf));
  87        if (n < 0) {
  88                perror("read");
  89                exit(1);
  90        }
  91
  92        if (n < E_HSIZE || memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0)
  93                goto notelf;
  94
  95        if (buf[E_IDENT+EI_CLASS] != ELFCLASS32
  96            || buf[E_IDENT+EI_DATA] != ELFDATA2MSB) {
  97                fprintf(stderr, "%s is not a big-endian 32-bit ELF image\n",
  98                        av[1]);
  99                exit(1);
 100        }
 101
 102        ph = GET_32BE(E_PHOFF);
 103        ps = GET_16BE(E_PHENTSIZE);
 104        np = GET_16BE(E_PHNUM);
 105        if (ph < E_HSIZE || ps < PH_HSIZE || np < 1)
 106                goto notelf;
 107        if (ph + (np + 1) * ps + nnote > n)
 108                goto nospace;
 109
 110        for (i = 0; i < np; ++i) {
 111                if (GET_32BE(ph + PH_TYPE) == PT_NOTE) {
 112                        fprintf(stderr, "%s already has a note entry\n",
 113                                av[1]);
 114                        exit(0);
 115                }
 116                ph += ps;
 117        }
 118
 119        /* XXX check that the area we want to use is all zeroes */
 120        for (i = 0; i < ps + nnote; ++i)
 121                if (buf[ph + i] != 0)
 122                        goto nospace;
 123
 124        /* fill in the program header entry */
 125        ns = ph + ps;
 126        PUT_32BE(ph + PH_TYPE, PT_NOTE);
 127        PUT_32BE(ph + PH_OFFSET, ns);
 128        PUT_32BE(ph + PH_FILESZ, nnote);
 129
 130        /* fill in the note area we point to */
 131        /* XXX we should probably make this a proper section */
 132        PUT_32BE(ns, strlen(arch) + 1);
 133        PUT_32BE(ns + 4, N_DESCR * 4);
 134        PUT_32BE(ns + 8, 0x1275);
 135        strcpy(&buf[ns + 12], arch);
 136        ns += 12 + strlen(arch) + 1;
 137        for (i = 0; i < N_DESCR; ++i)
 138                PUT_32BE(ns + i * 4, descr[i]);
 139
 140        /* Update the number of program headers */
 141        PUT_16BE(E_PHNUM, np + 1);
 142
 143        /* write back */
 144        lseek(fd, (long) 0, SEEK_SET);
 145        i = write(fd, buf, n);
 146        if (i < 0) {
 147                perror("write");
 148                exit(1);
 149        }
 150        if (i < n) {
 151                fprintf(stderr, "%s: write truncated\n", av[1]);
 152                exit(1);
 153        }
 154
 155        exit(0);
 156
 157 notelf:
 158        fprintf(stderr, "%s does not appear to be an ELF file\n", av[0]);
 159        exit(1);
 160
 161 nospace:
 162        fprintf(stderr, "sorry, I can't find space in %s to put the note\n",
 163                av[0]);
 164        exit(1);
 165}
 166