| 1 | /* Read a symbol table in MIPS' format (Third-Eye). |
| 2 | |
| 3 | Copyright (C) 1986-2016 Free Software Foundation, Inc. |
| 4 | |
| 5 | Contributed by Alessandro Forin (af@cs.cmu.edu) at CMU. Major work |
| 6 | by Per Bothner, John Gilmore and Ian Lance Taylor at Cygnus Support. |
| 7 | |
| 8 | This file is part of GDB. |
| 9 | |
| 10 | This program is free software; you can redistribute it and/or modify |
| 11 | it under the terms of the GNU General Public License as published by |
| 12 | the Free Software Foundation; either version 3 of the License, or |
| 13 | (at your option) any later version. |
| 14 | |
| 15 | This program is distributed in the hope that it will be useful, |
| 16 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | GNU General Public License for more details. |
| 19 | |
| 20 | You should have received a copy of the GNU General Public License |
| 21 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 22 | |
| 23 | /* Read symbols from an ECOFF file. Most of the work is done in |
| 24 | mdebugread.c. */ |
| 25 | |
| 26 | #include "defs.h" |
| 27 | #include "bfd.h" |
| 28 | #include "symtab.h" |
| 29 | #include "objfiles.h" |
| 30 | #include "buildsym.h" |
| 31 | #include "stabsread.h" |
| 32 | |
| 33 | #include "coff/sym.h" |
| 34 | #include "coff/internal.h" |
| 35 | #include "coff/ecoff.h" |
| 36 | #include "libcoff.h" /* Private BFD COFF information. */ |
| 37 | #include "libecoff.h" /* Private BFD ECOFF information. */ |
| 38 | #include "elf/common.h" |
| 39 | #include "elf/internal.h" |
| 40 | #include "elf/mips.h" |
| 41 | |
| 42 | #include "psymtab.h" |
| 43 | |
| 44 | static void |
| 45 | read_alphacoff_dynamic_symtab (struct section_offsets *, |
| 46 | struct objfile *objfile); |
| 47 | |
| 48 | /* Initialize anything that needs initializing when a completely new |
| 49 | symbol file is specified (not just adding some symbols from another |
| 50 | file, e.g. a shared library). */ |
| 51 | |
| 52 | static void |
| 53 | mipscoff_new_init (struct objfile *ignore) |
| 54 | { |
| 55 | stabsread_new_init (); |
| 56 | buildsym_new_init (); |
| 57 | } |
| 58 | |
| 59 | /* Initialize to read a symbol file (nothing to do). */ |
| 60 | |
| 61 | static void |
| 62 | mipscoff_symfile_init (struct objfile *objfile) |
| 63 | { |
| 64 | } |
| 65 | |
| 66 | /* Read a symbol file from a file. */ |
| 67 | |
| 68 | static void |
| 69 | mipscoff_symfile_read (struct objfile *objfile, int symfile_flags) |
| 70 | { |
| 71 | bfd *abfd = objfile->obfd; |
| 72 | struct cleanup *back_to; |
| 73 | |
| 74 | init_minimal_symbol_collection (); |
| 75 | back_to = make_cleanup_discard_minimal_symbols (); |
| 76 | |
| 77 | /* Now that the executable file is positioned at symbol table, |
| 78 | process it and define symbols accordingly. */ |
| 79 | |
| 80 | if (!((*ecoff_backend (abfd)->debug_swap.read_debug_info) |
| 81 | (abfd, (asection *) NULL, &ecoff_data (abfd)->debug_info))) |
| 82 | error (_("Error reading symbol table: %s"), bfd_errmsg (bfd_get_error ())); |
| 83 | |
| 84 | mdebug_build_psymtabs (objfile, &ecoff_backend (abfd)->debug_swap, |
| 85 | &ecoff_data (abfd)->debug_info); |
| 86 | |
| 87 | /* Add alpha coff dynamic symbols. */ |
| 88 | |
| 89 | read_alphacoff_dynamic_symtab (objfile->section_offsets, objfile); |
| 90 | |
| 91 | /* Install any minimal symbols that have been collected as the current |
| 92 | minimal symbols for this objfile. */ |
| 93 | |
| 94 | install_minimal_symbols (objfile); |
| 95 | do_cleanups (back_to); |
| 96 | } |
| 97 | |
| 98 | /* Perform any local cleanups required when we are done with a |
| 99 | particular objfile. */ |
| 100 | |
| 101 | static void |
| 102 | mipscoff_symfile_finish (struct objfile *objfile) |
| 103 | { |
| 104 | } |
| 105 | |
| 106 | /* Alpha OSF/1 encapsulates the dynamic symbols in ELF format in a |
| 107 | standard COFF section. The ELF format for the symbols differs from |
| 108 | the format defined in elf/external.h. It seems that a normal ELF |
| 109 | 32-bit format is used, and the representation only changes because |
| 110 | longs are 64-bit on the alpha. In addition, the handling of |
| 111 | text/data section indices for symbols is different from the ELF |
| 112 | ABI. As the BFD linker currently does not support dynamic linking |
| 113 | on the alpha, there seems to be no reason to pollute BFD with |
| 114 | another mixture of object file formats for now. */ |
| 115 | |
| 116 | /* Format of an alpha external ELF symbol. */ |
| 117 | |
| 118 | typedef struct |
| 119 | { |
| 120 | unsigned char st_name[4]; /* Symbol name, index in string table. */ |
| 121 | unsigned char st_pad[4]; /* Pad to long word boundary. */ |
| 122 | unsigned char st_value[8]; /* Value of the symbol. */ |
| 123 | unsigned char st_size[4]; /* Associated symbol size. */ |
| 124 | unsigned char st_info[1]; /* Type and binding attributes. */ |
| 125 | unsigned char st_other[1]; /* No defined meaning, 0. */ |
| 126 | unsigned char st_shndx[2]; /* Associated section index. */ |
| 127 | } Elfalpha_External_Sym; |
| 128 | |
| 129 | /* Format of an alpha external ELF dynamic info structure. */ |
| 130 | |
| 131 | typedef struct |
| 132 | { |
| 133 | unsigned char d_tag[4]; /* Tag. */ |
| 134 | unsigned char d_pad[4]; /* Pad to long word boundary. */ |
| 135 | union |
| 136 | { |
| 137 | unsigned char d_ptr[8]; /* Pointer value. */ |
| 138 | unsigned char d_val[4]; /* Integer value. */ |
| 139 | } |
| 140 | d_un; |
| 141 | } Elfalpha_External_Dyn; |
| 142 | |
| 143 | /* Struct to obtain the section pointers for alpha dynamic symbol info. */ |
| 144 | |
| 145 | struct alphacoff_dynsecinfo |
| 146 | { |
| 147 | asection *sym_sect; /* Section pointer for .dynsym section. */ |
| 148 | asection *str_sect; /* Section pointer for .dynstr section. */ |
| 149 | asection *dyninfo_sect; /* Section pointer for .dynamic section. */ |
| 150 | asection *got_sect; /* Section pointer for .got section. */ |
| 151 | }; |
| 152 | |
| 153 | /* We are called once per section from read_alphacoff_dynamic_symtab. |
| 154 | We need to examine each section we are passed, check to see if it |
| 155 | is something we are interested in processing, and if so, stash away |
| 156 | some access information for the section. */ |
| 157 | |
| 158 | static void |
| 159 | alphacoff_locate_sections (bfd *ignore_abfd, asection *sectp, void *sip) |
| 160 | { |
| 161 | struct alphacoff_dynsecinfo *si; |
| 162 | |
| 163 | si = (struct alphacoff_dynsecinfo *) sip; |
| 164 | |
| 165 | if (strcmp (sectp->name, ".dynsym") == 0) |
| 166 | si->sym_sect = sectp; |
| 167 | else if (strcmp (sectp->name, ".dynstr") == 0) |
| 168 | si->str_sect = sectp; |
| 169 | else if (strcmp (sectp->name, ".dynamic") == 0) |
| 170 | si->dyninfo_sect = sectp; |
| 171 | else if (strcmp (sectp->name, ".got") == 0) |
| 172 | si->got_sect = sectp; |
| 173 | } |
| 174 | |
| 175 | /* Scan an alpha dynamic symbol table for symbols of interest and add |
| 176 | them to the minimal symbol table. */ |
| 177 | |
| 178 | static void |
| 179 | read_alphacoff_dynamic_symtab (struct section_offsets *section_offsets, |
| 180 | struct objfile *objfile) |
| 181 | { |
| 182 | bfd *abfd = objfile->obfd; |
| 183 | struct alphacoff_dynsecinfo si; |
| 184 | char *sym_secptr; |
| 185 | char *str_secptr; |
| 186 | char *dyninfo_secptr; |
| 187 | char *got_secptr; |
| 188 | bfd_size_type sym_secsize; |
| 189 | bfd_size_type str_secsize; |
| 190 | bfd_size_type dyninfo_secsize; |
| 191 | bfd_size_type got_secsize; |
| 192 | int sym_count; |
| 193 | int i; |
| 194 | int stripped; |
| 195 | Elfalpha_External_Sym *x_symp; |
| 196 | char *dyninfo_p; |
| 197 | char *dyninfo_end; |
| 198 | int got_entry_size = 8; |
| 199 | int dt_mips_local_gotno = -1; |
| 200 | int dt_mips_gotsym = -1; |
| 201 | struct cleanup *cleanups; |
| 202 | |
| 203 | /* We currently only know how to handle alpha dynamic symbols. */ |
| 204 | if (bfd_get_arch (abfd) != bfd_arch_alpha) |
| 205 | return; |
| 206 | |
| 207 | /* Locate the dynamic symbols sections and read them in. */ |
| 208 | memset ((char *) &si, 0, sizeof (si)); |
| 209 | bfd_map_over_sections (abfd, alphacoff_locate_sections, (void *) & si); |
| 210 | if (si.sym_sect == NULL || si.str_sect == NULL |
| 211 | || si.dyninfo_sect == NULL || si.got_sect == NULL) |
| 212 | return; |
| 213 | |
| 214 | sym_secsize = bfd_get_section_size (si.sym_sect); |
| 215 | str_secsize = bfd_get_section_size (si.str_sect); |
| 216 | dyninfo_secsize = bfd_get_section_size (si.dyninfo_sect); |
| 217 | got_secsize = bfd_get_section_size (si.got_sect); |
| 218 | sym_secptr = (char *) xmalloc (sym_secsize); |
| 219 | cleanups = make_cleanup (xfree, sym_secptr); |
| 220 | str_secptr = (char *) xmalloc (str_secsize); |
| 221 | make_cleanup (xfree, str_secptr); |
| 222 | dyninfo_secptr = (char *) xmalloc (dyninfo_secsize); |
| 223 | make_cleanup (xfree, dyninfo_secptr); |
| 224 | got_secptr = (char *) xmalloc (got_secsize); |
| 225 | make_cleanup (xfree, got_secptr); |
| 226 | |
| 227 | if (!bfd_get_section_contents (abfd, si.sym_sect, sym_secptr, |
| 228 | (file_ptr) 0, sym_secsize)) |
| 229 | { |
| 230 | do_cleanups (cleanups); |
| 231 | return; |
| 232 | } |
| 233 | if (!bfd_get_section_contents (abfd, si.str_sect, str_secptr, |
| 234 | (file_ptr) 0, str_secsize)) |
| 235 | { |
| 236 | do_cleanups (cleanups); |
| 237 | return; |
| 238 | } |
| 239 | if (!bfd_get_section_contents (abfd, si.dyninfo_sect, dyninfo_secptr, |
| 240 | (file_ptr) 0, dyninfo_secsize)) |
| 241 | { |
| 242 | do_cleanups (cleanups); |
| 243 | return; |
| 244 | } |
| 245 | if (!bfd_get_section_contents (abfd, si.got_sect, got_secptr, |
| 246 | (file_ptr) 0, got_secsize)) |
| 247 | { |
| 248 | do_cleanups (cleanups); |
| 249 | return; |
| 250 | } |
| 251 | |
| 252 | /* Find the number of local GOT entries and the index for the |
| 253 | first dynamic symbol in the GOT. */ |
| 254 | for (dyninfo_p = dyninfo_secptr, dyninfo_end = dyninfo_p + dyninfo_secsize; |
| 255 | dyninfo_p < dyninfo_end; |
| 256 | dyninfo_p += sizeof (Elfalpha_External_Dyn)) |
| 257 | { |
| 258 | Elfalpha_External_Dyn *x_dynp = (Elfalpha_External_Dyn *) dyninfo_p; |
| 259 | long dyn_tag; |
| 260 | |
| 261 | dyn_tag = bfd_h_get_32 (abfd, (bfd_byte *) x_dynp->d_tag); |
| 262 | if (dyn_tag == DT_NULL) |
| 263 | break; |
| 264 | else if (dyn_tag == DT_MIPS_LOCAL_GOTNO) |
| 265 | { |
| 266 | if (dt_mips_local_gotno < 0) |
| 267 | dt_mips_local_gotno |
| 268 | = bfd_h_get_32 (abfd, (bfd_byte *) x_dynp->d_un.d_val); |
| 269 | } |
| 270 | else if (dyn_tag == DT_MIPS_GOTSYM) |
| 271 | { |
| 272 | if (dt_mips_gotsym < 0) |
| 273 | dt_mips_gotsym |
| 274 | = bfd_h_get_32 (abfd, (bfd_byte *) x_dynp->d_un.d_val); |
| 275 | } |
| 276 | } |
| 277 | if (dt_mips_local_gotno < 0 || dt_mips_gotsym < 0) |
| 278 | { |
| 279 | do_cleanups (cleanups); |
| 280 | return; |
| 281 | } |
| 282 | |
| 283 | /* Scan all dynamic symbols and enter them into the minimal symbol |
| 284 | table if appropriate. */ |
| 285 | sym_count = sym_secsize / sizeof (Elfalpha_External_Sym); |
| 286 | stripped = (bfd_get_symcount (abfd) == 0); |
| 287 | |
| 288 | /* Skip first symbol, which is a null dummy. */ |
| 289 | for (i = 1, x_symp = (Elfalpha_External_Sym *) sym_secptr + 1; |
| 290 | i < sym_count; |
| 291 | i++, x_symp++) |
| 292 | { |
| 293 | unsigned long strx; |
| 294 | char *name; |
| 295 | bfd_vma sym_value; |
| 296 | unsigned char sym_info; |
| 297 | unsigned int sym_shndx; |
| 298 | int isglobal; |
| 299 | enum minimal_symbol_type ms_type; |
| 300 | |
| 301 | strx = bfd_h_get_32 (abfd, (bfd_byte *) x_symp->st_name); |
| 302 | if (strx >= str_secsize) |
| 303 | continue; |
| 304 | name = str_secptr + strx; |
| 305 | if (*name == '\0' || *name == '.') |
| 306 | continue; |
| 307 | |
| 308 | sym_value = bfd_h_get_64 (abfd, (bfd_byte *) x_symp->st_value); |
| 309 | sym_info = bfd_h_get_8 (abfd, (bfd_byte *) x_symp->st_info); |
| 310 | sym_shndx = bfd_h_get_16 (abfd, (bfd_byte *) x_symp->st_shndx); |
| 311 | if (sym_shndx >= (SHN_LORESERVE & 0xffff)) |
| 312 | sym_shndx += SHN_LORESERVE - (SHN_LORESERVE & 0xffff); |
| 313 | isglobal = (ELF_ST_BIND (sym_info) == STB_GLOBAL); |
| 314 | |
| 315 | if (sym_shndx == SHN_UNDEF) |
| 316 | { |
| 317 | /* Handle undefined functions which are defined in a shared |
| 318 | library. */ |
| 319 | if (ELF_ST_TYPE (sym_info) != STT_FUNC |
| 320 | || ELF_ST_BIND (sym_info) != STB_GLOBAL) |
| 321 | continue; |
| 322 | |
| 323 | ms_type = mst_solib_trampoline; |
| 324 | |
| 325 | /* If sym_value is nonzero, it points to the shared library |
| 326 | trampoline entry, which is what we are looking for. |
| 327 | |
| 328 | If sym_value is zero, then we have to get the GOT entry |
| 329 | for the symbol. |
| 330 | |
| 331 | If the GOT entry is nonzero, it represents the quickstart |
| 332 | address of the function and we use that as the symbol |
| 333 | value. |
| 334 | |
| 335 | If the GOT entry is zero, the function address has to be |
| 336 | resolved by the runtime loader before the executable is |
| 337 | started. We are unable to find any meaningful address |
| 338 | for these functions in the executable file, so we skip |
| 339 | them. */ |
| 340 | if (sym_value == 0) |
| 341 | { |
| 342 | int got_entry_offset = |
| 343 | (i - dt_mips_gotsym + dt_mips_local_gotno) * got_entry_size; |
| 344 | |
| 345 | if (got_entry_offset < 0 || got_entry_offset >= got_secsize) |
| 346 | continue; |
| 347 | sym_value = |
| 348 | bfd_h_get_64 (abfd, |
| 349 | (bfd_byte *) (got_secptr + got_entry_offset)); |
| 350 | if (sym_value == 0) |
| 351 | continue; |
| 352 | } |
| 353 | } |
| 354 | else |
| 355 | { |
| 356 | /* Symbols defined in the executable itself. We only care |
| 357 | about them if this is a stripped executable, otherwise |
| 358 | they have been retrieved from the normal symbol table |
| 359 | already. */ |
| 360 | if (!stripped) |
| 361 | continue; |
| 362 | |
| 363 | if (sym_shndx == SHN_MIPS_TEXT) |
| 364 | { |
| 365 | if (isglobal) |
| 366 | ms_type = mst_text; |
| 367 | else |
| 368 | ms_type = mst_file_text; |
| 369 | } |
| 370 | else if (sym_shndx == SHN_MIPS_DATA) |
| 371 | { |
| 372 | if (isglobal) |
| 373 | ms_type = mst_data; |
| 374 | else |
| 375 | ms_type = mst_file_data; |
| 376 | } |
| 377 | else if (sym_shndx == SHN_MIPS_ACOMMON) |
| 378 | { |
| 379 | if (isglobal) |
| 380 | ms_type = mst_bss; |
| 381 | else |
| 382 | ms_type = mst_file_bss; |
| 383 | } |
| 384 | else if (sym_shndx == SHN_ABS) |
| 385 | { |
| 386 | ms_type = mst_abs; |
| 387 | } |
| 388 | else |
| 389 | { |
| 390 | continue; |
| 391 | } |
| 392 | } |
| 393 | |
| 394 | prim_record_minimal_symbol (name, sym_value, ms_type, objfile); |
| 395 | } |
| 396 | |
| 397 | do_cleanups (cleanups); |
| 398 | } |
| 399 | |
| 400 | /* Initialization. */ |
| 401 | |
| 402 | static const struct sym_fns ecoff_sym_fns = |
| 403 | { |
| 404 | mipscoff_new_init, /* init anything gbl to entire symtab */ |
| 405 | mipscoff_symfile_init, /* read initial info, setup for sym_read() */ |
| 406 | mipscoff_symfile_read, /* read a symbol file into symtab */ |
| 407 | NULL, /* sym_read_psymbols */ |
| 408 | mipscoff_symfile_finish, /* finished with file, cleanup */ |
| 409 | default_symfile_offsets, /* dummy FIXME til implem sym reloc */ |
| 410 | default_symfile_segments, /* Get segment information from a file. */ |
| 411 | NULL, |
| 412 | default_symfile_relocate, /* Relocate a debug section. */ |
| 413 | NULL, /* sym_probe_fns */ |
| 414 | &psym_functions |
| 415 | }; |
| 416 | |
| 417 | /* Provide a prototype to silence -Wmissing-prototypes. */ |
| 418 | void _initialize_mipsread (void); |
| 419 | |
| 420 | void |
| 421 | _initialize_mipsread (void) |
| 422 | { |
| 423 | add_symtab_fns (bfd_target_ecoff_flavour, &ecoff_sym_fns); |
| 424 | } |