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