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176 lines
4.1 KiB
176 lines
4.1 KiB
20 years ago
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/*
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* Program to hack in a PT_NOTE program header entry in an ELF file.
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* This is needed for OF on RS/6000s to load an image correctly.
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* Note that OF needs a program header entry for the note, not an
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* ELF section.
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*
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* Copyright 2000 Paul Mackerras.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Usage: addnote zImage
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <string.h>
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char arch[] = "PowerPC";
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#define N_DESCR 6
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unsigned int descr[N_DESCR] = {
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#if 1
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/* values for IBM RS/6000 machines */
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0xffffffff, /* real-mode = true */
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0x00c00000, /* real-base, i.e. where we expect OF to be */
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0xffffffff, /* real-size */
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0xffffffff, /* virt-base */
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0xffffffff, /* virt-size */
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0x4000, /* load-base */
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#else
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/* values for longtrail CHRP */
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0, /* real-mode = false */
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0xffffffff, /* real-base */
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0xffffffff, /* real-size */
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0xffffffff, /* virt-base */
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0xffffffff, /* virt-size */
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0x00600000, /* load-base */
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#endif
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};
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unsigned char buf[512];
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#define GET_16BE(off) ((buf[off] << 8) + (buf[(off)+1]))
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#define GET_32BE(off) ((GET_16BE(off) << 16) + GET_16BE((off)+2))
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#define PUT_16BE(off, v) (buf[off] = ((v) >> 8) & 0xff, \
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buf[(off) + 1] = (v) & 0xff)
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#define PUT_32BE(off, v) (PUT_16BE((off), (v) >> 16), \
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PUT_16BE((off) + 2, (v)))
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/* Structure of an ELF file */
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#define E_IDENT 0 /* ELF header */
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#define E_PHOFF 28
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#define E_PHENTSIZE 42
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#define E_PHNUM 44
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#define E_HSIZE 52 /* size of ELF header */
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#define EI_MAGIC 0 /* offsets in E_IDENT area */
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#define EI_CLASS 4
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#define EI_DATA 5
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#define PH_TYPE 0 /* ELF program header */
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#define PH_OFFSET 4
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#define PH_FILESZ 16
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#define PH_HSIZE 32 /* size of program header */
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#define PT_NOTE 4 /* Program header type = note */
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#define ELFCLASS32 1
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#define ELFDATA2MSB 2
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unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };
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int main(int ac, char **av)
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{
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int fd, n, i;
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int ph, ps, np;
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int nnote, ns;
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if (ac != 2) {
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fprintf(stderr, "Usage: %s elf-file\n", av[0]);
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exit(1);
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}
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fd = open(av[1], O_RDWR);
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if (fd < 0) {
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perror(av[1]);
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exit(1);
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}
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nnote = strlen(arch) + 1 + (N_DESCR + 3) * 4;
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n = read(fd, buf, sizeof(buf));
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if (n < 0) {
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perror("read");
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exit(1);
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}
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if (n < E_HSIZE || memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0)
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goto notelf;
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if (buf[E_IDENT+EI_CLASS] != ELFCLASS32
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|| buf[E_IDENT+EI_DATA] != ELFDATA2MSB) {
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fprintf(stderr, "%s is not a big-endian 32-bit ELF image\n",
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av[1]);
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exit(1);
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}
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ph = GET_32BE(E_PHOFF);
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ps = GET_16BE(E_PHENTSIZE);
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np = GET_16BE(E_PHNUM);
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if (ph < E_HSIZE || ps < PH_HSIZE || np < 1)
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goto notelf;
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if (ph + (np + 1) * ps + nnote > n)
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goto nospace;
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for (i = 0; i < np; ++i) {
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if (GET_32BE(ph + PH_TYPE) == PT_NOTE) {
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fprintf(stderr, "%s already has a note entry\n",
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av[1]);
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exit(0);
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}
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ph += ps;
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}
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/* XXX check that the area we want to use is all zeroes */
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for (i = 0; i < ps + nnote; ++i)
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if (buf[ph + i] != 0)
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goto nospace;
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/* fill in the program header entry */
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ns = ph + ps;
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PUT_32BE(ph + PH_TYPE, PT_NOTE);
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PUT_32BE(ph + PH_OFFSET, ns);
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PUT_32BE(ph + PH_FILESZ, nnote);
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/* fill in the note area we point to */
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/* XXX we should probably make this a proper section */
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PUT_32BE(ns, strlen(arch) + 1);
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PUT_32BE(ns + 4, N_DESCR * 4);
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PUT_32BE(ns + 8, 0x1275);
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strcpy(&buf[ns + 12], arch);
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ns += 12 + strlen(arch) + 1;
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for (i = 0; i < N_DESCR; ++i)
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PUT_32BE(ns + i * 4, descr[i]);
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/* Update the number of program headers */
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PUT_16BE(E_PHNUM, np + 1);
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/* write back */
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lseek(fd, (long) 0, SEEK_SET);
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i = write(fd, buf, n);
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if (i < 0) {
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perror("write");
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exit(1);
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}
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if (i < n) {
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fprintf(stderr, "%s: write truncated\n", av[1]);
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exit(1);
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}
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exit(0);
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notelf:
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fprintf(stderr, "%s does not appear to be an ELF file\n", av[0]);
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exit(1);
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nospace:
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fprintf(stderr, "sorry, I can't find space in %s to put the note\n",
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av[0]);
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exit(1);
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}
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