1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ 2 /* This file is derived from the GAS 2.1.4 assembler control file. 3 The GAS product is under the GNU General Public License, version 2 or later. 4 As such, this file is also under that license. 5 6 If the file format changes in the COFF object, this file should be 7 subsequently updated to reflect the changes. 8 9 The actual loader module only uses a few of these structures. The full 10 set is documented here because I received the full set. If you wish 11 more information about COFF, then O'Reilly has a very excellent book. 12 */ 13 14 #define E_SYMNMLEN 8 /* Number of characters in a symbol name */ 15 #define E_FILNMLEN 14 /* Number of characters in a file name */ 16 #define E_DIMNUM 4 /* Number of array dimensions in auxiliary entry */ 17 18 /* 19 * These defines are byte order independent. There is no alignment of fields 20 * permitted in the structures. Therefore they are declared as characters 21 * and the values loaded from the character positions. It also makes it 22 * nice to have it "endian" independent. 23 */ 24 25 /* Load a short int from the following tables with little-endian formats */ 26 #define COFF_SHORT_L(ps) ((short)(((unsigned short)((unsigned char)ps[1])<<8)|\ 27 ((unsigned short)((unsigned char)ps[0])))) 28 29 /* Load a long int from the following tables with little-endian formats */ 30 #define COFF_LONG_L(ps) (((long)(((unsigned long)((unsigned char)ps[3])<<24) |\ 31 ((unsigned long)((unsigned char)ps[2])<<16) |\ 32 ((unsigned long)((unsigned char)ps[1])<<8) |\ 33 ((unsigned long)((unsigned char)ps[0]))))) 34 35 /* Load a short int from the following tables with big-endian formats */ 36 #define COFF_SHORT_H(ps) ((short)(((unsigned short)((unsigned char)ps[0])<<8)|\ 37 ((unsigned short)((unsigned char)ps[1])))) 38 39 /* Load a long int from the following tables with big-endian formats */ 40 #define COFF_LONG_H(ps) (((long)(((unsigned long)((unsigned char)ps[0])<<24) |\ 41 ((unsigned long)((unsigned char)ps[1])<<16) |\ 42 ((unsigned long)((unsigned char)ps[2])<<8) |\ 43 ((unsigned long)((unsigned char)ps[3]))))) 44 45 /* These may be overridden later by brain dead implementations which generate 46 a big-endian header with little-endian data. In that case, generate a 47 replacement macro which tests a flag and uses either of the two above 48 as appropriate. */ 49 50 #define COFF_LONG(v) COFF_LONG_L(v) 51 #define COFF_SHORT(v) COFF_SHORT_L(v) 52 53 /*** coff information for Intel 386/486. */ 54 55 /********************** FILE HEADER **********************/ 56 57 struct COFF_filehdr { 58 char f_magic[2]; /* magic number */ 59 char f_nscns[2]; /* number of sections */ 60 char f_timdat[4]; /* time & date stamp */ 61 char f_symptr[4]; /* file pointer to symtab */ 62 char f_nsyms[4]; /* number of symtab entries */ 63 char f_opthdr[2]; /* sizeof(optional hdr) */ 64 char f_flags[2]; /* flags */ 65 }; 66 67 /* 68 * Bits for f_flags: 69 * 70 * F_RELFLG relocation info stripped from file 71 * F_EXEC file is executable (i.e. no unresolved external 72 * references) 73 * F_LNNO line numbers stripped from file 74 * F_LSYMS local symbols stripped from file 75 * F_MINMAL this is a minimal object file (".m") output of fextract 76 * F_UPDATE this is a fully bound update file, output of ogen 77 * F_SWABD this file has had its bytes swabbed (in names) 78 * F_AR16WR this file has the byte ordering of an AR16WR 79 * (e.g. 11/70) machine 80 * F_AR32WR this file has the byte ordering of an AR32WR machine 81 * (e.g. vax and iNTEL 386) 82 * F_AR32W this file has the byte ordering of an AR32W machine 83 * (e.g. 3b,maxi) 84 * F_PATCH file contains "patch" list in optional header 85 * F_NODF (minimal file only) no decision functions for 86 * replaced functions 87 */ 88 89 #define COFF_F_RELFLG 0000001 90 #define COFF_F_EXEC 0000002 91 #define COFF_F_LNNO 0000004 92 #define COFF_F_LSYMS 0000010 93 #define COFF_F_MINMAL 0000020 94 #define COFF_F_UPDATE 0000040 95 #define COFF_F_SWABD 0000100 96 #define COFF_F_AR16WR 0000200 97 #define COFF_F_AR32WR 0000400 98 #define COFF_F_AR32W 0001000 99 #define COFF_F_PATCH 0002000 100 #define COFF_F_NODF 0002000 101 102 #define COFF_I386MAGIC 0x14c /* Linux's system */ 103 104 #if 0 /* Perhaps, someday, these formats may be used. */ 105 #define COFF_I386PTXMAGIC 0x154 106 #define COFF_I386AIXMAGIC 0x175 /* IBM's AIX system */ 107 #define COFF_I386BADMAG(x) ((COFF_SHORT((x).f_magic) != COFF_I386MAGIC) \ 108 && COFF_SHORT((x).f_magic) != COFF_I386PTXMAGIC \ 109 && COFF_SHORT((x).f_magic) != COFF_I386AIXMAGIC) 110 #else 111 #define COFF_I386BADMAG(x) (COFF_SHORT((x).f_magic) != COFF_I386MAGIC) 112 #endif 113 114 #define COFF_FILHDR struct COFF_filehdr 115 #define COFF_FILHSZ sizeof(COFF_FILHDR) 116 117 /********************** AOUT "OPTIONAL HEADER" **********************/ 118 119 /* Linux COFF must have this "optional" header. Standard COFF has no entry 120 location for the "entry" point. They normally would start with the first 121 location of the .text section. This is not a good idea for linux. So, 122 the use of this "optional" header is not optional. It is required. 123 124 Do not be tempted to assume that the size of the optional header is 125 a constant and simply index the next byte by the size of this structure. 126 Use the 'f_opthdr' field in the main coff header for the size of the 127 structure actually written to the file!! 128 */ 129 130 typedef struct 131 { 132 char magic[2]; /* type of file */ 133 char vstamp[2]; /* version stamp */ 134 char tsize[4]; /* text size in bytes, padded to FW bdry */ 135 char dsize[4]; /* initialized data " " */ 136 char bsize[4]; /* uninitialized data " " */ 137 char entry[4]; /* entry pt. */ 138 char text_start[4]; /* base of text used for this file */ 139 char data_start[4]; /* base of data used for this file */ 140 } 141 COFF_AOUTHDR; 142 143 #define COFF_AOUTSZ (sizeof(COFF_AOUTHDR)) 144 145 #define COFF_STMAGIC 0401 146 #define COFF_OMAGIC 0404 147 #define COFF_JMAGIC 0407 /* dirty text and data image, can't share */ 148 #define COFF_DMAGIC 0410 /* dirty text segment, data aligned */ 149 #define COFF_ZMAGIC 0413 /* The proper magic number for executables */ 150 #define COFF_SHMAGIC 0443 /* shared library header */ 151 152 /********************** SECTION HEADER **********************/ 153 154 struct COFF_scnhdr { 155 char s_name[8]; /* section name */ 156 char s_paddr[4]; /* physical address, aliased s_nlib */ 157 char s_vaddr[4]; /* virtual address */ 158 char s_size[4]; /* section size */ 159 char s_scnptr[4]; /* file ptr to raw data for section */ 160 char s_relptr[4]; /* file ptr to relocation */ 161 char s_lnnoptr[4]; /* file ptr to line numbers */ 162 char s_nreloc[2]; /* number of relocation entries */ 163 char s_nlnno[2]; /* number of line number entries */ 164 char s_flags[4]; /* flags */ 165 }; 166 167 #define COFF_SCNHDR struct COFF_scnhdr 168 #define COFF_SCNHSZ sizeof(COFF_SCNHDR) 169 170 /* 171 * names of "special" sections 172 */ 173 174 #define COFF_TEXT ".text" 175 #define COFF_DATA ".data" 176 #define COFF_BSS ".bss" 177 #define COFF_COMMENT ".comment" 178 #define COFF_LIB ".lib" 179 180 #define COFF_SECT_TEXT 0 /* Section for instruction code */ 181 #define COFF_SECT_DATA 1 /* Section for initialized globals */ 182 #define COFF_SECT_BSS 2 /* Section for un-initialized globals */ 183 #define COFF_SECT_REQD 3 /* Minimum number of sections for good file */ 184 185 #define COFF_STYP_REG 0x00 /* regular segment */ 186 #define COFF_STYP_DSECT 0x01 /* dummy segment */ 187 #define COFF_STYP_NOLOAD 0x02 /* no-load segment */ 188 #define COFF_STYP_GROUP 0x04 /* group segment */ 189 #define COFF_STYP_PAD 0x08 /* .pad segment */ 190 #define COFF_STYP_COPY 0x10 /* copy section */ 191 #define COFF_STYP_TEXT 0x20 /* .text segment */ 192 #define COFF_STYP_DATA 0x40 /* .data segment */ 193 #define COFF_STYP_BSS 0x80 /* .bss segment */ 194 #define COFF_STYP_INFO 0x200 /* .comment section */ 195 #define COFF_STYP_OVER 0x400 /* overlay section */ 196 #define COFF_STYP_LIB 0x800 /* library section */ 197 198 /* 199 * Shared libraries have the following section header in the data field for 200 * each library. 201 */ 202 203 struct COFF_slib { 204 char sl_entsz[4]; /* Size of this entry */ 205 char sl_pathndx[4]; /* size of the header field */ 206 }; 207 208 #define COFF_SLIBHD struct COFF_slib 209 #define COFF_SLIBSZ sizeof(COFF_SLIBHD) 210 211 /********************** LINE NUMBERS **********************/ 212 213 /* 1 line number entry for every "breakpointable" source line in a section. 214 * Line numbers are grouped on a per function basis; first entry in a function 215 * grouping will have l_lnno = 0 and in place of physical address will be the 216 * symbol table index of the function name. 217 */ 218 219 struct COFF_lineno { 220 union { 221 char l_symndx[4]; /* function name symbol index, iff l_lnno == 0*/ 222 char l_paddr[4]; /* (physical) address of line number */ 223 } l_addr; 224 char l_lnno[2]; /* line number */ 225 }; 226 227 #define COFF_LINENO struct COFF_lineno 228 #define COFF_LINESZ 6 229 230 /********************** SYMBOLS **********************/ 231 232 #define COFF_E_SYMNMLEN 8 /* # characters in a short symbol name */ 233 #define COFF_E_FILNMLEN 14 /* # characters in a file name */ 234 #define COFF_E_DIMNUM 4 /* # array dimensions in auxiliary entry */ 235 236 /* 237 * All symbols and sections have the following definition 238 */ 239 240 struct COFF_syment 241 { 242 union { 243 char e_name[E_SYMNMLEN]; /* Symbol name (first 8 characters) */ 244 struct { 245 char e_zeroes[4]; /* Leading zeros */ 246 char e_offset[4]; /* Offset if this is a header section */ 247 } e; 248 } e; 249 250 char e_value[4]; /* Value (address) of the segment */ 251 char e_scnum[2]; /* Section number */ 252 char e_type[2]; /* Type of section */ 253 char e_sclass[1]; /* Loader class */ 254 char e_numaux[1]; /* Number of auxiliary entries which follow */ 255 }; 256 257 #define COFF_N_BTMASK (0xf) /* Mask for important class bits */ 258 #define COFF_N_TMASK (0x30) /* Mask for important type bits */ 259 #define COFF_N_BTSHFT (4) /* # bits to shift class field */ 260 #define COFF_N_TSHIFT (2) /* # bits to shift type field */ 261 262 /* 263 * Auxiliary entries because the main table is too limiting. 264 */ 265 266 union COFF_auxent { 267 268 /* 269 * Debugger information 270 */ 271 272 struct { 273 char x_tagndx[4]; /* str, un, or enum tag indx */ 274 union { 275 struct { 276 char x_lnno[2]; /* declaration line number */ 277 char x_size[2]; /* str/union/array size */ 278 } x_lnsz; 279 char x_fsize[4]; /* size of function */ 280 } x_misc; 281 282 union { 283 struct { /* if ISFCN, tag, or .bb */ 284 char x_lnnoptr[4]; /* ptr to fcn line # */ 285 char x_endndx[4]; /* entry ndx past block end */ 286 } x_fcn; 287 288 struct { /* if ISARY, up to 4 dimen. */ 289 char x_dimen[E_DIMNUM][2]; 290 } x_ary; 291 } x_fcnary; 292 293 char x_tvndx[2]; /* tv index */ 294 } x_sym; 295 296 /* 297 * Source file names (debugger information) 298 */ 299 300 union { 301 char x_fname[E_FILNMLEN]; 302 struct { 303 char x_zeroes[4]; 304 char x_offset[4]; 305 } x_n; 306 } x_file; 307 308 /* 309 * Section information 310 */ 311 312 struct { 313 char x_scnlen[4]; /* section length */ 314 char x_nreloc[2]; /* # relocation entries */ 315 char x_nlinno[2]; /* # line numbers */ 316 } x_scn; 317 318 /* 319 * Transfer vector (branch table) 320 */ 321 322 struct { 323 char x_tvfill[4]; /* tv fill value */ 324 char x_tvlen[2]; /* length of .tv */ 325 char x_tvran[2][2]; /* tv range */ 326 } x_tv; /* info about .tv section (in auxent of symbol .tv)) */ 327 }; 328 329 #define COFF_SYMENT struct COFF_syment 330 #define COFF_SYMESZ 18 331 #define COFF_AUXENT union COFF_auxent 332 #define COFF_AUXESZ 18 333 334 #define COFF_ETEXT "etext" 335 336 /********************** RELOCATION DIRECTIVES **********************/ 337 338 struct COFF_reloc { 339 char r_vaddr[4]; /* Virtual address of item */ 340 char r_symndx[4]; /* Symbol index in the symtab */ 341 char r_type[2]; /* Relocation type */ 342 }; 343 344 #define COFF_RELOC struct COFF_reloc 345 #define COFF_RELSZ 10 346 347 #define COFF_DEF_DATA_SECTION_ALIGNMENT 4 348 #define COFF_DEF_BSS_SECTION_ALIGNMENT 4 349 #define COFF_DEF_TEXT_SECTION_ALIGNMENT 4 350 351 /* For new sections we haven't heard of before */ 352 #define COFF_DEF_SECTION_ALIGNMENT 4 353
