Subversion Repositories or1k

/* Read ELF (Executable and Linking Format) object files for GDB.

   Copyright 1991, 92, 93, 94, 95, 96, 1998 Free Software Foundation, Inc.

   Written by Fred Fish at Cygnus Support.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 2 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 59 Temple Place - Suite 330,

   Boston, MA 02111-1307, USA.  */

#include "defs.h"

#include "bfd.h"

#include "gdb_string.h"

#include "elf-bfd.h"

#include "elf/mips.h"

#include "symtab.h"

#include "symfile.h"

#include "objfiles.h"

#include "buildsym.h"

#include "stabsread.h"

#include "gdb-stabs.h"

#include "complaints.h"

#include "demangle.h"

extern void _initialize_elfread PARAMS ((void));

/* The struct elfinfo is available only during ELF symbol table and

   psymtab reading.  It is destroyed at the completion of psymtab-reading.

   It's local to elf_symfile_read.  */

struct elfinfo

  {

    file_ptr dboffset;          /* Offset to dwarf debug section */

    unsigned int dbsize;        /* Size of dwarf debug section */

    file_ptr lnoffset;          /* Offset to dwarf line number section */

    unsigned int lnsize;        /* Size of dwarf line number section */

    asection *stabsect;         /* Section pointer for .stab section */

    asection *stabindexsect;    /* Section pointer for .stab.index section */

    asection *mdebugsect;       /* Section pointer for .mdebug section */

  };

/* Various things we might complain about... */

struct complaint section_info_complaint =

{"elf/stab section information %s without a preceding file symbol", 0, 0};

struct complaint section_info_dup_complaint =

{"duplicated elf/stab section information for %s", 0, 0};

struct complaint stab_info_mismatch_complaint =

{"elf/stab section information missing for %s", 0, 0};

struct complaint stab_info_questionable_complaint =

{"elf/stab section information questionable for %s", 0, 0};

static void

elf_symfile_init PARAMS ((struct objfile *));

static void

elf_new_init PARAMS ((struct objfile *));

static void

elf_symfile_read PARAMS ((struct objfile *, int));

static void

elf_symfile_finish PARAMS ((struct objfile *));

static void

elf_symtab_read PARAMS ((struct objfile *, int));

static void

free_elfinfo PARAMS ((void *));

static struct minimal_symbol *

  record_minimal_symbol_and_info PARAMS ((char *, CORE_ADDR,

                                          enum minimal_symbol_type, char *,

                                          asection * bfd_section,

                                          struct objfile *));

static void

elf_locate_sections PARAMS ((bfd *, asection *, void *));

/* We are called once per section from elf_symfile_read.  We

   need to examine each section we are passed, check to see

   if it is something we are interested in processing, and

   if so, stash away some access information for the section.

   For now we recognize the dwarf debug information sections and

   line number sections from matching their section names.  The

   ELF definition is no real help here since it has no direct

   knowledge of DWARF (by design, so any debugging format can be

   used).

   We also recognize the ".stab" sections used by the Sun compilers

   released with Solaris 2.

   FIXME: The section names should not be hardwired strings (what

   should they be?  I don't think most object file formats have enough

   section flags to specify what kind of debug section it is

   -kingdon).  */

static void

elf_locate_sections (ignore_abfd, sectp, eip)

     bfd *ignore_abfd;

     asection *sectp;

     PTR eip;

{

  register struct elfinfo *ei;

  ei = (struct elfinfo *) eip;

  if (STREQ (sectp->name, ".debug"))

    {

      ei->dboffset = sectp->filepos;

      ei->dbsize = bfd_get_section_size_before_reloc (sectp);

    }

  else if (STREQ (sectp->name, ".line"))

    {

      ei->lnoffset = sectp->filepos;

      ei->lnsize = bfd_get_section_size_before_reloc (sectp);

    }

  else if (STREQ (sectp->name, ".stab"))

    {

      ei->stabsect = sectp;

    }

  else if (STREQ (sectp->name, ".stab.index"))

    {

      ei->stabindexsect = sectp;

    }

  else if (STREQ (sectp->name, ".mdebug"))

    {

      ei->mdebugsect = sectp;

    }

}

#if 0                           /* Currently unused */

char *

elf_interpreter (abfd)

     bfd *abfd;

{

  sec_ptr interp_sec;

  unsigned size;

  char *interp = NULL;

  interp_sec = bfd_get_section_by_name (abfd, ".interp");

  if (interp_sec)

    {

      size = bfd_section_size (abfd, interp_sec);

      interp = alloca (size);

      if (bfd_get_section_contents (abfd, interp_sec, interp, (file_ptr) 0,

                                    size))

        {

          interp = savestring (interp, size - 1);

        }

      else

        {

          interp = NULL;

        }

    }

  return (interp);

}

#endif

static struct minimal_symbol *

record_minimal_symbol_and_info (name, address, ms_type, info, bfd_section,

                                objfile)

     char *name;

     CORE_ADDR address;

     enum minimal_symbol_type ms_type;

     char *info;                /* FIXME, is this really char *? */

     asection *bfd_section;

     struct objfile *objfile;

{

  int section;

  /* Guess the section from the type.  This is likely to be wrong in

     some cases.  */

  switch (ms_type)

    {

    case mst_text:

    case mst_file_text:

      section = SECT_OFF_TEXT;

#ifdef SMASH_TEXT_ADDRESS

      SMASH_TEXT_ADDRESS (address);

#endif

      break;

    case mst_data:

    case mst_file_data:

      section = SECT_OFF_DATA;

      break;

    case mst_bss:

    case mst_file_bss:

      section = SECT_OFF_BSS;

      break;

    default:

      section = -1;

      break;

    }

  return prim_record_minimal_symbol_and_info

    (name, address, ms_type, info, section, bfd_section, objfile);

}

/*

   LOCAL FUNCTION

   elf_symtab_read -- read the symbol table of an ELF file

   SYNOPSIS

   void elf_symtab_read (struct objfile *objfile, int dynamic)

   DESCRIPTION

   Given an objfile and a flag that specifies whether or not the objfile

   is for an executable or not (may be shared library for example), add

   all the global function and data symbols to the minimal symbol table.

   In stabs-in-ELF, as implemented by Sun, there are some local symbols

   defined in the ELF symbol table, which can be used to locate

   the beginnings of sections from each ".o" file that was linked to

   form the executable objfile.  We gather any such info and record it

   in data structures hung off the objfile's private data.

 */

static void

elf_symtab_read (objfile, dynamic)

     struct objfile *objfile;

     int dynamic;

{

  long storage_needed;

  asymbol *sym;

  asymbol **symbol_table;

  long number_of_symbols;

  long i;

  int index;

  struct cleanup *back_to;

  CORE_ADDR symaddr;

  CORE_ADDR offset;

  enum minimal_symbol_type ms_type;

  /* If sectinfo is nonNULL, it contains section info that should end up

     filed in the objfile.  */

  struct stab_section_info *sectinfo = NULL;

  /* If filesym is nonzero, it points to a file symbol, but we haven't

     seen any section info for it yet.  */

  asymbol *filesym = 0;

#ifdef SOFUN_ADDRESS_MAYBE_MISSING

  /* Name of filesym, as saved on the symbol_obstack.  */

  char *filesymname = obsavestring ("", 0, &objfile->symbol_obstack);

#endif

  struct dbx_symfile_info *dbx = objfile->sym_stab_info;

  unsigned long size;

  int stripped = (bfd_get_symcount (objfile->obfd) == 0);

  if (dynamic)

    {

      storage_needed = bfd_get_dynamic_symtab_upper_bound (objfile->obfd);

      /* Nothing to be done if there is no dynamic symtab.  */

      if (storage_needed < 0)

        return;

    }

  else

    {

      storage_needed = bfd_get_symtab_upper_bound (objfile->obfd);

      if (storage_needed < 0)

        error ("Can't read symbols from %s: %s", bfd_get_filename (objfile->obfd),

               bfd_errmsg (bfd_get_error ()));

    }

  if (storage_needed > 0)

    {

      symbol_table = (asymbol **) xmalloc (storage_needed);

      back_to = make_cleanup (free, symbol_table);

      if (dynamic)

        number_of_symbols = bfd_canonicalize_dynamic_symtab (objfile->obfd,

                                                             symbol_table);

      else

        number_of_symbols = bfd_canonicalize_symtab (objfile->obfd, symbol_table);

      if (number_of_symbols < 0)

        error ("Can't read symbols from %s: %s", bfd_get_filename (objfile->obfd),

               bfd_errmsg (bfd_get_error ()));

      /* FIXME: Should use section specific offset, not SECT_OFF_TEXT. */

      offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT);

      for (i = 0; i < number_of_symbols; i++)

        {

          sym = symbol_table[i];

          if (sym->name == NULL || *sym->name == '\0')

            {

              /* Skip names that don't exist (shouldn't happen), or names

                 that are null strings (may happen). */

              continue;

            }

          if (dynamic

              && sym->section == &bfd_und_section

              && (sym->flags & BSF_FUNCTION))

            {

              struct minimal_symbol *msym;

              /* Symbol is a reference to a function defined in

                 a shared library.

                 If its value is non zero then it is usually the address

                 of the corresponding entry in the procedure linkage table,

                 plus the desired section offset.

                 If its value is zero then the dynamic linker has to resolve

                 the symbol. We are unable to find any meaningful address

                 for this symbol in the executable file, so we skip it.  */

              symaddr = sym->value;

              if (symaddr == 0)

                continue;

              symaddr += offset;

              msym = record_minimal_symbol_and_info

                ((char *) sym->name, symaddr,

                 mst_solib_trampoline, NULL, sym->section, objfile);

#ifdef SOFUN_ADDRESS_MAYBE_MISSING

              if (msym != NULL)

                msym->filename = filesymname;

#endif

              continue;

            }

          /* If it is a nonstripped executable, do not enter dynamic

             symbols, as the dynamic symbol table is usually a subset

             of the main symbol table.  */

          if (dynamic && !stripped)

            continue;

          if (sym->flags & BSF_FILE)

            {

              /* STT_FILE debugging symbol that helps stabs-in-elf debugging.

                 Chain any old one onto the objfile; remember new sym.  */

              if (sectinfo != NULL)

                {

                  sectinfo->next = dbx->stab_section_info;

                  dbx->stab_section_info = sectinfo;

                  sectinfo = NULL;

                }

              filesym = sym;

#ifdef SOFUN_ADDRESS_MAYBE_MISSING

              filesymname =

                obsavestring ((char *) filesym->name, strlen (filesym->name),

                              &objfile->symbol_obstack);

#endif

            }

          else if (sym->flags & (BSF_GLOBAL | BSF_LOCAL | BSF_WEAK))

            {

              struct minimal_symbol *msym;

              /* Select global/local/weak symbols.  Note that bfd puts abs

                 symbols in their own section, so all symbols we are

                 interested in will have a section. */

              /* Bfd symbols are section relative. */

              symaddr = sym->value + sym->section->vma;

              /* Relocate all non-absolute symbols by the section offset.  */

              if (sym->section != &bfd_abs_section)

                {

                  symaddr += offset;

                }

              /* For non-absolute symbols, use the type of the section

                 they are relative to, to intuit text/data.  Bfd provides

                 no way of figuring this out for absolute symbols. */

              if (sym->section == &bfd_abs_section)

                {

                  /* This is a hack to get the minimal symbol type

                     right for Irix 5, which has absolute addresses

                     with special section indices for dynamic symbols. */

                  unsigned short shndx =

                  ((elf_symbol_type *) sym)->internal_elf_sym.st_shndx;

                  switch (shndx)

                    {

                    case SHN_MIPS_TEXT:

                      ms_type = mst_text;

                      break;

                    case SHN_MIPS_DATA:

                      ms_type = mst_data;

                      break;

                    case SHN_MIPS_ACOMMON:

                      ms_type = mst_bss;

                      break;

                    default:

                      ms_type = mst_abs;

                    }

                  /* If it is an Irix dynamic symbol, skip section name

                     symbols, relocate all others by section offset. */

                  if (ms_type != mst_abs)

                    {

                      if (sym->name[0] == '.')

                        continue;

                      symaddr += offset;

                    }

                }

              else if (sym->section->flags & SEC_CODE)

                {

                  if (sym->flags & BSF_GLOBAL)

                    {

                      ms_type = mst_text;

                    }

                  else if ((sym->name[0] == '.' && sym->name[1] == 'L')

                           || ((sym->flags & BSF_LOCAL)

                               && sym->name[0] == '$'

                               && sym->name[1] == 'L'))

                    /* Looks like a compiler-generated label.  Skip it.

                       The assembler should be skipping these (to keep

                       executables small), but apparently with gcc on the

                       delta m88k SVR4, it loses.  So to have us check too

                       should be harmless (but I encourage people to fix this

                       in the assembler instead of adding checks here).  */

                    continue;

#ifdef HARRIS_TARGET

                  else if (sym->name[0] == '.' && sym->name[1] == '.')

                    {

                      /* Looks like a Harris compiler generated label for the

                         purpose of marking instructions that are relevant to

                         DWARF dies.  The assembler can't get rid of these

                         because they are relocatable addresses that the

                         linker needs to resolve. */

                      continue;

                    }

#endif

                  else

                    {

                      ms_type = mst_file_text;

                    }

                }

              else if (sym->section->flags & SEC_ALLOC)

                {

                  if (sym->flags & BSF_GLOBAL)

                    {

                      if (sym->section->flags & SEC_LOAD)

                        {

                          ms_type = mst_data;

                        }

                      else

                        {

                          ms_type = mst_bss;

                        }

                    }

                  else if (sym->flags & BSF_LOCAL)

                    {

                      /* Named Local variable in a Data section.  Check its

                         name for stabs-in-elf.  The STREQ macro checks the

                         first character inline, so we only actually do a

                         strcmp function call on names that start with 'B'

                         or 'D' */

                      index = SECT_OFF_MAX;

                      if (STREQ ("Bbss.bss", sym->name))

                        {

                          index = SECT_OFF_BSS;

                        }

                      else if (STREQ ("Ddata.data", sym->name))

                        {

                          index = SECT_OFF_DATA;

                        }

                      else if (STREQ ("Drodata.rodata", sym->name))

                        {

                          index = SECT_OFF_RODATA;

                        }

                      if (index != SECT_OFF_MAX)

                        {

                          /* Found a special local symbol.  Allocate a

                             sectinfo, if needed, and fill it in.  */

                          if (sectinfo == NULL)

                            {

                              sectinfo = (struct stab_section_info *)

                                xmmalloc (objfile->md, sizeof (*sectinfo));

                              memset ((PTR) sectinfo, 0, sizeof (*sectinfo));

                              if (filesym == NULL)

                                {

                                  complain (&section_info_complaint,

                                            sym->name);

                                }

                              else

                                {

                                  sectinfo->filename =

                                    (char *) filesym->name;

                                }

                            }

                          if (sectinfo->sections[index] != 0)

                            {

                              complain (&section_info_dup_complaint,

                                        sectinfo->filename);

                            }

                          /* Bfd symbols are section relative. */

                          symaddr = sym->value + sym->section->vma;

                          /* Relocate non-absolute symbols by the section offset. */

                          if (sym->section != &bfd_abs_section)

                            {

                              symaddr += offset;

                            }

                          sectinfo->sections[index] = symaddr;

                          /* The special local symbols don't go in the

                             minimal symbol table, so ignore this one. */

                          continue;

                        }

                      /* Not a special stabs-in-elf symbol, do regular

                         symbol processing. */

                      if (sym->section->flags & SEC_LOAD)

                        {

                          ms_type = mst_file_data;

                        }

                      else

                        {

                          ms_type = mst_file_bss;

                        }

                    }

                  else

                    {

                      ms_type = mst_unknown;

                    }

                }

              else

                {

                  /* FIXME:  Solaris2 shared libraries include lots of

                     odd "absolute" and "undefined" symbols, that play

                     hob with actions like finding what function the PC

                     is in.  Ignore them if they aren't text, data, or bss.  */

                  /* ms_type = mst_unknown; */

                  continue;     /* Skip this symbol. */

                }

              /* Pass symbol size field in via BFD.  FIXME!!!  */

              size = ((elf_symbol_type *) sym)->internal_elf_sym.st_size;

              msym = record_minimal_symbol_and_info

                ((char *) sym->name, symaddr,

                 ms_type, (PTR) size, sym->section, objfile);

#ifdef SOFUN_ADDRESS_MAYBE_MISSING

              if (msym != NULL)

                msym->filename = filesymname;

#endif

#ifdef ELF_MAKE_MSYMBOL_SPECIAL

              ELF_MAKE_MSYMBOL_SPECIAL (sym, msym);

#endif

            }

        }

      do_cleanups (back_to);

    }

}

/* Scan and build partial symbols for a symbol file.

   We have been initialized by a call to elf_symfile_init, which

   currently does nothing.

   SECTION_OFFSETS is a set of offsets to apply to relocate the symbols

   in each section.  We simplify it down to a single offset for all

   symbols.  FIXME.

   MAINLINE is true if we are reading the main symbol

   table (as opposed to a shared lib or dynamically loaded file).

   This function only does the minimum work necessary for letting the

   user "name" things symbolically; it does not read the entire symtab.

   Instead, it reads the external and static symbols and puts them in partial

   symbol tables.  When more extensive information is requested of a

   file, the corresponding partial symbol table is mutated into a full

   fledged symbol table by going back and reading the symbols

   for real.

   We look for sections with specific names, to tell us what debug

   format to look for:  FIXME!!!

   dwarf_build_psymtabs() builds psymtabs for DWARF symbols;

   elfstab_build_psymtabs() handles STABS symbols;

   mdebug_build_psymtabs() handles ECOFF debugging information.

   Note that ELF files have a "minimal" symbol table, which looks a lot

   like a COFF symbol table, but has only the minimal information necessary

   for linking.  We process this also, and use the information to

   build gdb's minimal symbol table.  This gives us some minimal debugging

   capability even for files compiled without -g.  */

static void

elf_symfile_read (objfile, mainline)

     struct objfile *objfile;

     int mainline;

{

  bfd *abfd = objfile->obfd;

  struct elfinfo ei;

  struct cleanup *back_to;

  CORE_ADDR offset;

  init_minimal_symbol_collection ();

  back_to = make_cleanup ((make_cleanup_func) discard_minimal_symbols, 0);

  memset ((char *) &ei, 0, sizeof (ei));

  /* Allocate struct to keep track of the symfile */

  objfile->sym_stab_info = (struct dbx_symfile_info *)

    xmmalloc (objfile->md, sizeof (struct dbx_symfile_info));

  memset ((char *) objfile->sym_stab_info, 0, sizeof (struct dbx_symfile_info));

  make_cleanup (free_elfinfo, (PTR) objfile);

  /* Process the normal ELF symbol table first.  This may write some

     chain of info into the dbx_symfile_info in objfile->sym_stab_info,

     which can later be used by elfstab_offset_sections.  */

  elf_symtab_read (objfile, 0);

  /* Add the dynamic symbols.  */

  elf_symtab_read (objfile, 1);

  /* Now process debugging information, which is contained in

     special ELF sections. */

  /* If we are reinitializing, or if we have never loaded syms yet,

     set table to empty.  MAINLINE is cleared so that *_read_psymtab

     functions do not all also re-initialize the psymbol table. */

  if (mainline)

    {

      init_psymbol_list (objfile, 0);

      mainline = 0;

    }

  /* We first have to find them... */

  bfd_map_over_sections (abfd, elf_locate_sections, (PTR) & ei);

  /* ELF debugging information is inserted into the psymtab in the

     order of least informative first - most informative last.  Since

     the psymtab table is searched `most recent insertion first' this

     increases the probability that more detailed debug information

     for a section is found.

     For instance, an object file might contain both .mdebug (XCOFF)

     and .debug_info (DWARF2) sections then .mdebug is inserted first

     (searched last) and DWARF2 is inserted last (searched first).  If

     we don't do this then the XCOFF info is found first - for code in

     an included file XCOFF info is useless. */

  if (ei.mdebugsect)

    {

      const struct ecoff_debug_swap *swap;

      /* .mdebug section, presumably holding ECOFF debugging

         information.  */

      swap = get_elf_backend_data (abfd)->elf_backend_ecoff_debug_swap;

      if (swap)

        elfmdebug_build_psymtabs (objfile, swap, ei.mdebugsect);

    }

  if (ei.stabsect)

    {

      asection *str_sect;

      /* Stab sections have an associated string table that looks like

         a separate section.  */

      str_sect = bfd_get_section_by_name (abfd, ".stabstr");

      /* FIXME should probably warn about a stab section without a stabstr.  */

      if (str_sect)

        elfstab_build_psymtabs (objfile,

                                mainline,

                                ei.stabsect->filepos,

                                bfd_section_size (abfd, ei.stabsect),

                                str_sect->filepos,

                                bfd_section_size (abfd, str_sect));

    }

  if (dwarf2_has_info (abfd))

    {

      /* DWARF 2 sections */

      dwarf2_build_psymtabs (objfile, mainline);

    }

  else if (ei.dboffset && ei.lnoffset)

    {

      /* DWARF sections */

      dwarf_build_psymtabs (objfile,

                            mainline,

                            ei.dboffset, ei.dbsize,

                            ei.lnoffset, ei.lnsize);

    }

  /* Install any minimal symbols that have been collected as the current

     minimal symbols for this objfile. */

  install_minimal_symbols (objfile);

  do_cleanups (back_to);

}

/* This cleans up the objfile's sym_stab_info pointer, and the chain of

   stab_section_info's, that might be dangling from it.  */

static void

free_elfinfo (objp)

     PTR objp;

{

  struct objfile *objfile = (struct objfile *) objp;

  struct dbx_symfile_info *dbxinfo = objfile->sym_stab_info;

  struct stab_section_info *ssi, *nssi;

  ssi = dbxinfo->stab_section_info;

  while (ssi)

    {

      nssi = ssi->next;

      mfree (objfile->md, ssi);

      ssi = nssi;

    }

  dbxinfo->stab_section_info = 0;        /* Just say No mo info about this.  */

}

/* Initialize anything that needs initializing when a completely new symbol

   file is specified (not just adding some symbols from another file, e.g. a

   shared library).

   We reinitialize buildsym, since we may be reading stabs from an ELF file.  */

static void

elf_new_init (ignore)

     struct objfile *ignore;

{

  stabsread_new_init ();

  buildsym_new_init ();