346168a2c6
extra info in the minimal symbol. (elf_symtab_read): The extra info is the size of an ELF object, which was kludged to us in the `udata' field of the BFD symbol. Gag me with a crowbar... (elf_symfile_read): Keep track of both the absolute load address, and the offset between load addr and symbols. Handle STABS as well as DWARF sections, passing the absolute load address to elfstab_build_psymtabs. * objfiles.c (free_objfile): Eliminate storage leaks. Contributed by <Peter.Schauer@regent.e-technik.tu-muenchen.dbp.de>. * symfile.c (symfile_bfd_open): Comment where name is freed. * symmisc.c (extend_psymbol_list): Comment where list is freed.
459 lines
14 KiB
C
459 lines
14 KiB
C
/* Read ELF (Executable and Linking Format) object files for GDB.
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Copyright 1991, 1992 Free Software Foundation, Inc.
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Written by Fred Fish at Cygnus Support.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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/************************************************************************
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* *
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* NOTICE *
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* *
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* This file is still under construction. When it is complete, this *
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* notice will be removed. Until then, direct any questions or changes *
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* to Fred Fish at Cygnus Support (fnf@cygnus.com) *
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* *
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* FIXME Still needs support for shared libraries. *
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* FIXME Still needs support for core files. *
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* FIXME The ".debug" and ".line" section names are hardwired. *
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* *
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************************************************************************/
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#include "defs.h"
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#include "elf/common.h"
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#include "elf/external.h"
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#include "elf/internal.h"
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#include "bfd.h"
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#include "symtab.h"
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#include "symfile.h"
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#include "objfiles.h"
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#include "buildsym.h"
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#define STREQ(a,b) (strcmp((a),(b))==0)
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struct elfinfo {
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unsigned int dboffset; /* Offset to dwarf debug section */
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unsigned int dbsize; /* Size of dwarf debug section */
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unsigned int lnoffset; /* Offset to dwarf line number section */
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unsigned int lnsize; /* Size of dwarf line number section */
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asection *stabsect; /* Section pointer for .stab section */
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asection *stabindexsect; /* Section pointer for .stab.index section */
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};
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static void
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elf_symfile_init PARAMS ((struct objfile *));
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static void
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elf_new_init PARAMS ((struct objfile *));
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static void
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elf_symfile_read PARAMS ((struct objfile *, CORE_ADDR, int));
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static void
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elf_symfile_finish PARAMS ((struct objfile *));
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static void
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elf_symtab_read PARAMS ((bfd *, CORE_ADDR, struct objfile *));
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static void
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record_minimal_symbol PARAMS ((char *, CORE_ADDR, enum minimal_symbol_type,
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struct objfile *));
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static void
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elf_locate_sections PARAMS ((bfd *, asection *, PTR));
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/* We are called once per section from elf_symfile_read. We
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need to examine each section we are passed, check to see
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if it is something we are interested in processing, and
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if so, stash away some access information for the section.
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For now we recognize the dwarf debug information sections and
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line number sections from matching their section names. The
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ELF definition is no real help here since it has no direct
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knowledge of DWARF (by design, so any debugging format can be
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used).
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We also recognize the ".stab" sections used by the Sun compilers
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released with Solaris 2.
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FIXME: The section names should not be hardwired strings. */
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static void
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elf_locate_sections (ignore_abfd, sectp, eip)
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bfd *ignore_abfd;
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asection *sectp;
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PTR eip;
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{
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register struct elfinfo *ei;
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ei = (struct elfinfo *) eip;
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if (STREQ (sectp -> name, ".debug"))
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{
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ei -> dboffset = sectp -> filepos;
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ei -> dbsize = bfd_get_section_size_before_reloc (sectp);
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}
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else if (STREQ (sectp -> name, ".line"))
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{
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ei -> lnoffset = sectp -> filepos;
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ei -> lnsize = bfd_get_section_size_before_reloc (sectp);
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}
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else if (STREQ (sectp -> name, ".stab"))
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{
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ei -> stabsect = sectp;
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}
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else if (STREQ (sectp -> name, ".stab.index"))
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{
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ei -> stabindexsect = sectp;
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}
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}
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#if 0 /* Currently unused */
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char *
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elf_interpreter (abfd)
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bfd *abfd;
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{
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sec_ptr interp_sec;
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unsigned size;
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char *interp = NULL;
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interp_sec = bfd_get_section_by_name (abfd, ".interp");
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if (interp_sec)
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{
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size = bfd_section_size (abfd, interp_sec);
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interp = alloca (size);
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if (bfd_get_section_contents (abfd, interp_sec, interp, (file_ptr)0,
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size))
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{
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interp = savestring (interp, size - 1);
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}
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else
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{
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interp = NULL;
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}
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}
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return (interp);
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}
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#endif
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/*
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LOCAL FUNCTION
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record_minimal_symbol -- add entry to minimal symbol table
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SYNOPSIS
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static void record_minimal_symbol (char *name, CORE_ADDR address)
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DESCRIPTION
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Given a pointer to the name of a symbol that should be added to the
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minimal symbol table and the address associated with that symbol, records
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this information for later use in building the minimal symbol table.
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*/
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static void
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record_minimal_symbol (name, address, ms_type, objfile)
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char *name;
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CORE_ADDR address;
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enum minimal_symbol_type ms_type;
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struct objfile *objfile;
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{
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name = obsavestring (name, strlen (name), &objfile -> symbol_obstack);
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prim_record_minimal_symbol (name, address, ms_type);
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}
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static void
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record_minimal_symbol_and_info (name, address, ms_type, info, objfile)
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char *name;
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CORE_ADDR address;
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enum minimal_symbol_type ms_type;
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char *info; /* FIXME, is this really char *? */
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struct objfile *objfile;
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{
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name = obsavestring (name, strlen (name), &objfile -> symbol_obstack);
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prim_record_minimal_symbol_and_info (name, address, ms_type, info);
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}
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/*
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LOCAL FUNCTION
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elf_symtab_read -- read the symbol table of an ELF file
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SYNOPSIS
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void elf_symtab_read (bfd *abfd, CORE_ADDR addr,
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struct objfile *objfile)
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DESCRIPTION
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Given an open bfd, a base address to relocate symbols to, and a
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flag that specifies whether or not this bfd is for an executable
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or not (may be shared library for example), add all the global
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function and data symbols to the minimal symbol table.
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*/
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static void
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elf_symtab_read (abfd, addr, objfile)
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bfd *abfd;
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CORE_ADDR addr;
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struct objfile *objfile;
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{
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unsigned int storage_needed;
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asymbol *sym;
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asymbol **symbol_table;
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unsigned int number_of_symbols;
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unsigned int i;
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struct cleanup *back_to;
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CORE_ADDR symaddr;
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enum minimal_symbol_type ms_type;
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storage_needed = get_symtab_upper_bound (abfd);
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if (storage_needed > 0)
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{
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symbol_table = (asymbol **) xmalloc (storage_needed);
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back_to = make_cleanup (free, symbol_table);
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number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
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for (i = 0; i < number_of_symbols; i++)
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{
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sym = *symbol_table++;
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/* Select global/weak symbols that are defined in a specific section.
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Note that bfd now puts abs symbols in their own section, so
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all symbols we are interested in will have a section. */
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if ((sym -> flags & (BSF_GLOBAL | BSF_WEAK))
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&& (sym -> section != NULL))
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{
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symaddr = sym -> value;
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/* Relocate all non-absolute symbols by base address. */
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if (sym -> section != &bfd_abs_section)
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{
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symaddr += addr;
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}
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/* For non-absolute symbols, use the type of the section
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they are relative to, to intuit text/data. Bfd provides
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no way of figuring this out for absolute symbols. */
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if (sym -> section -> flags & SEC_CODE)
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{
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ms_type = mst_text;
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}
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else if (sym -> section -> flags & SEC_DATA)
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{
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ms_type = mst_data;
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}
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else
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{
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ms_type = mst_unknown;
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}
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/* Pass symbol size field in via BFD. FIXME!!! */
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record_minimal_symbol_and_info ((char *) sym -> name,
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symaddr, ms_type, sym->udata, objfile);
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}
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}
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do_cleanups (back_to);
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}
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}
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/* Scan and build partial symbols for a symbol file.
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We have been initialized by a call to elf_symfile_init, which
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currently does nothing.
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ADDR is the address relative to which the symbols in it are (e.g.
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the base address of the text segment).
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MAINLINE is true if we are reading the main symbol
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table (as opposed to a shared lib or dynamically loaded file).
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This function only does the minimum work necessary for letting the
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user "name" things symbolically; it does not read the entire symtab.
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Instead, it reads the external and static symbols and puts them in partial
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symbol tables. When more extensive information is requested of a
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file, the corresponding partial symbol table is mutated into a full
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fledged symbol table by going back and reading the symbols
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for real.
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We look for sections with specific names, to tell us what debug
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format to look for: FIXME!!!
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dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
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elfstab_build_psymtabs() handles STABS symbols.
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Note that ELF files have a "minimal" symbol table, which looks a lot
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like a COFF symbol table, but has only the minimal information necessary
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for linking. We process this also, and use the information to
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build gdb's minimal symbol table. This gives us some minimal debugging
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capability even for files compiled without -g. */
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static void
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elf_symfile_read (objfile, addr, mainline)
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struct objfile *objfile;
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CORE_ADDR addr;
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int mainline;
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{
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bfd *abfd = objfile->obfd;
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struct elfinfo ei;
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struct cleanup *back_to;
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asection *text_sect;
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CORE_ADDR offset;
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init_minimal_symbol_collection ();
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back_to = make_cleanup (discard_minimal_symbols, 0);
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/* Compute the amount to relocate all symbols by. The value passed in
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as ADDR is typically either the actual address of the text section,
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or a user specified address. By subtracting off the actual address
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of the text section, we can compute the relocation amount. */
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text_sect = bfd_get_section_by_name (objfile -> obfd, ".text");
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offset = addr - bfd_section_vma (objfile -> obfd, text_sect);
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/* Process the normal ELF symbol table first. */
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elf_symtab_read (abfd, offset, objfile);
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/* Now process debugging information, which is contained in
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special ELF sections. We first have to find them... */
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(void) memset ((char *) &ei, 0, sizeof (ei));
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bfd_map_over_sections (abfd, elf_locate_sections, (PTR) &ei);
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if (ei.dboffset && ei.lnoffset)
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{
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/* DWARF sections */
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dwarf_build_psymtabs (fileno ((FILE *)(abfd -> iostream)),
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bfd_get_filename (abfd),
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offset, mainline,
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ei.dboffset, ei.dbsize,
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ei.lnoffset, ei.lnsize, objfile);
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}
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if (ei.stabsect)
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{
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/* STABS sections */
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/* FIXME: Sun didn't really know how to implement this well.
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They made .stab sections that don't point to the .stabstr
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section with the sh_link field. BFD doesn't make string table
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sections visible to the caller. So we have to search the
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ELF section table, not the BFD section table, for the string
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table. */
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Elf_Internal_Shdr *elf_sect = bfd_elf_find_section (abfd, ".stabstr");
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if (elf_sect)
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elfstab_build_psymtabs (objfile,
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addr, /* We really pass the text seg addr, not the offset, here. */
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mainline,
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ei.stabsect->filepos, /* .stab offset */
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bfd_get_section_size_before_reloc (ei.stabsect),/* .stab size */
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elf_sect->sh_offset, /* .stabstr offset */
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elf_sect->sh_size); /* .stabstr size */
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}
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if (!have_partial_symbols ())
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{
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wrap_here ("");
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printf_filtered ("(no debugging symbols found)...");
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wrap_here ("");
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}
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/* Install any minimal symbols that have been collected as the current
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minimal symbols for this objfile. */
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install_minimal_symbols (objfile);
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do_cleanups (back_to);
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}
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/* Initialize anything that needs initializing when a completely new symbol
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file is specified (not just adding some symbols from another file, e.g. a
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shared library).
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We reinitialize buildsym, since we may be reading stabs from an ELF file. */
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static void
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elf_new_init (ignore)
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struct objfile *ignore;
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{
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buildsym_new_init ();
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}
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/* Perform any local cleanups required when we are done with a particular
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objfile. I.E, we are in the process of discarding all symbol information
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for an objfile, freeing up all memory held for it, and unlinking the
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objfile struct from the global list of known objfiles. */
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static void
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elf_symfile_finish (objfile)
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struct objfile *objfile;
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{
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if (objfile -> sym_private != NULL)
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{
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mfree (objfile -> md, objfile -> sym_private);
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}
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}
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/* ELF specific initialization routine for reading symbols.
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It is passed a pointer to a struct sym_fns which contains, among other
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things, the BFD for the file whose symbols are being read, and a slot for
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a pointer to "private data" which we can fill with goodies.
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For now at least, we have nothing in particular to do, so this function is
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just a stub. */
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static void
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elf_symfile_init (ignore)
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struct objfile *ignore;
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{
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}
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/* Register that we are able to handle ELF object file formats and DWARF
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debugging formats.
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Unlike other object file formats, where the debugging information format
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is implied by the object file format, the ELF object file format and the
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DWARF debugging information format are two distinct, and potentially
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separate entities. I.E. it is perfectly possible to have ELF objects
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with debugging formats other than DWARF. And it is conceivable that the
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DWARF debugging format might be used with another object file format,
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like COFF, by simply using COFF's custom section feature.
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GDB, and to a lesser extent BFD, should support the notion of separate
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object file formats and debugging information formats. For now, we just
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use "elf" in the same sense as "a.out" or "coff", to imply both the ELF
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object file format and the DWARF debugging format. */
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static struct sym_fns elf_sym_fns =
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{
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"elf", /* sym_name: name or name prefix of BFD target type */
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3, /* sym_namelen: number of significant sym_name chars */
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elf_new_init, /* sym_new_init: init anything gbl to entire symtab */
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elf_symfile_init, /* sym_init: read initial info, setup for sym_read() */
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elf_symfile_read, /* sym_read: read a symbol file into symtab */
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elf_symfile_finish, /* sym_finish: finished with file, cleanup */
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NULL /* next: pointer to next struct sym_fns */
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};
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void
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_initialize_elfread ()
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{
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add_symtab_fns (&elf_sym_fns);
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}
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