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 } 206