1
/* BFD back-end for linux flavored i386 a.out binaries.
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Copyright 1992, 1993, 1994, 1995, 1996, 1997, 2001, 2002
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Free Software Foundation, Inc.
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This file is part of BFD, the Binary File Descriptor library.
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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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#define TARGET_PAGE_SIZE 4096
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#define ZMAGIC_DISK_BLOCK_SIZE 1024
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#define SEGMENT_SIZE TARGET_PAGE_SIZE
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#define TEXT_START_ADDR 0x0
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#define N_SHARED_LIB(x) 0
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#define BYTES_IN_WORD 4
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#define MACHTYPE_OK(mtype) ((mtype) == M_386 || (mtype) == M_UNKNOWN)
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#include "aout/aout64.h"
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#include "aout/stab_gnu.h"
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#include "libaout.h" /* BFD a.out internal data structures */
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#define DEFAULT_ARCH bfd_arch_i386
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/* Do not "beautify" the CONCAT* macro args. Traditional C will not
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remove whitespace added here, and thus will fail to concatenate
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#define MY(OP) CONCAT2 (i386linux_,OP)
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#define TARGETNAME "a.out-i386-linux"
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extern const bfd_target MY(vec);
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/* We always generate QMAGIC files in preference to ZMAGIC files. It
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would be possible to make this a linker option, if that ever
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static void MY_final_link_callback
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PARAMS ((bfd *, file_ptr *, file_ptr *, file_ptr *));
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static boolean i386linux_bfd_final_link
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PARAMS ((bfd *, struct bfd_link_info *));
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static boolean i386linux_write_object_contents PARAMS ((bfd *));
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i386linux_bfd_final_link (abfd, info)
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struct bfd_link_info *info;
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obj_aout_subformat (abfd) = q_magic_format;
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return NAME(aout,final_link) (abfd, info, MY_final_link_callback);
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#define MY_bfd_final_link i386linux_bfd_final_link
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/* Set the machine type correctly. */
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i386linux_write_object_contents (abfd)
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struct external_exec exec_bytes;
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struct internal_exec *execp = exec_hdr (abfd);
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N_SET_MACHTYPE (*execp, M_386);
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obj_reloc_entry_size (abfd) = RELOC_STD_SIZE;
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WRITE_HEADERS(abfd, execp);
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#define MY_write_object_contents i386linux_write_object_contents
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/* Code to link against Linux a.out shared libraries. */
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/* See if a symbol name is a reference to the global offset table. */
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#ifndef GOT_REF_PREFIX
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#define GOT_REF_PREFIX "__GOT_"
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#define IS_GOT_SYM(name) \
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(strncmp (name, GOT_REF_PREFIX, sizeof GOT_REF_PREFIX - 1) == 0)
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/* See if a symbol name is a reference to the procedure linkage table. */
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#ifndef PLT_REF_PREFIX
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#define PLT_REF_PREFIX "__PLT_"
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#define IS_PLT_SYM(name) \
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(strncmp (name, PLT_REF_PREFIX, sizeof PLT_REF_PREFIX - 1) == 0)
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/* This string is used to generate specialized error messages. */
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#define NEEDS_SHRLIB "__NEEDS_SHRLIB_"
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/* This special symbol is a set vector that contains a list of
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pointers to fixup tables. It will be present in any dynamicly
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linked file. The linker generated fixup table should also be added
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to the list, and it should always appear in the second slot (the
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first one is a dummy with a magic number that is defined in
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#ifndef SHARABLE_CONFLICTS
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#define SHARABLE_CONFLICTS "__SHARABLE_CONFLICTS__"
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/* We keep a list of fixups. The terminology is a bit strange, but
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each fixup contains two 32 bit numbers. A regular fixup contains
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an address and a pointer, and at runtime we should store the
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address at the location pointed to by the pointer. A builtin fixup
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contains two pointers, and we should read the address using one
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pointer and store it at the location pointed to by the other
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pointer. Builtin fixups come into play when we have duplicate
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__GOT__ symbols for the same variable. The builtin fixup will copy
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the GOT pointer from one over into the other. */
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struct linux_link_hash_entry *h;
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/* Nonzero if this is a jump instruction that needs to be fixed,
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zero if this is just a pointer */
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/* We don't need a special hash table entry structure, but we do need
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to keep some information between linker passes, so we use a special
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struct linux_link_hash_entry
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struct aout_link_hash_entry root;
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struct linux_link_hash_table
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struct aout_link_hash_table root;
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/* First dynamic object found in link. */
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/* Number of fixups. */
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/* Number of builtin fixups. */
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size_t local_builtins;
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/* List of fixups. */
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struct fixup *fixup_list;
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static struct bfd_hash_entry *linux_link_hash_newfunc
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PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
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static struct bfd_link_hash_table *linux_link_hash_table_create
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static struct fixup *new_fixup
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PARAMS ((struct bfd_link_info *, struct linux_link_hash_entry *,
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static boolean linux_link_create_dynamic_sections
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PARAMS ((bfd *, struct bfd_link_info *));
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static boolean linux_add_one_symbol
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PARAMS ((struct bfd_link_info *, bfd *, const char *, flagword, asection *,
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bfd_vma, const char *, boolean, boolean,
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struct bfd_link_hash_entry **));
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static boolean linux_tally_symbols
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PARAMS ((struct linux_link_hash_entry *, PTR));
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static boolean linux_finish_dynamic_link
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PARAMS ((bfd *, struct bfd_link_info *));
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/* Routine to create an entry in an Linux link hash table. */
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static struct bfd_hash_entry *
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linux_link_hash_newfunc (entry, table, string)
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struct bfd_hash_entry *entry;
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struct bfd_hash_table *table;
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struct linux_link_hash_entry *ret = (struct linux_link_hash_entry *) entry;
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/* Allocate the structure if it has not already been allocated by a
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if (ret == (struct linux_link_hash_entry *) NULL)
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ret = ((struct linux_link_hash_entry *)
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bfd_hash_allocate (table, sizeof (struct linux_link_hash_entry)));
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return (struct bfd_hash_entry *) ret;
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/* Call the allocation method of the superclass. */
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ret = ((struct linux_link_hash_entry *)
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NAME(aout,link_hash_newfunc) ((struct bfd_hash_entry *) ret,
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/* Set local fields; there aren't any. */
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return (struct bfd_hash_entry *) ret;
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/* Create a Linux link hash table. */
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static struct bfd_link_hash_table *
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linux_link_hash_table_create (abfd)
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struct linux_link_hash_table *ret;
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bfd_size_type amt = sizeof (struct linux_link_hash_table);
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ret = (struct linux_link_hash_table *) bfd_alloc (abfd, amt);
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if (ret == (struct linux_link_hash_table *) NULL)
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return (struct bfd_link_hash_table *) NULL;
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if (! NAME(aout,link_hash_table_init) (&ret->root, abfd,
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linux_link_hash_newfunc))
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return (struct bfd_link_hash_table *) NULL;
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ret->fixup_count = 0;
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ret->local_builtins = 0;
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ret->fixup_list = NULL;
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return &ret->root.root;
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/* Look up an entry in a Linux link hash table. */
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#define linux_link_hash_lookup(table, string, create, copy, follow) \
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((struct linux_link_hash_entry *) \
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aout_link_hash_lookup (&(table)->root, (string), (create), (copy),\
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/* Traverse a Linux link hash table. */
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#define linux_link_hash_traverse(table, func, info) \
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(aout_link_hash_traverse \
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(boolean (*) PARAMS ((struct aout_link_hash_entry *, PTR))) (func), \
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/* Get the Linux link hash table from the info structure. This is
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#define linux_hash_table(p) ((struct linux_link_hash_table *) ((p)->hash))
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/* Store the information for a new fixup. */
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static struct fixup *
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new_fixup (info, h, value, builtin)
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struct bfd_link_info *info;
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struct linux_link_hash_entry *h;
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f = (struct fixup *) bfd_hash_allocate (&info->hash->table,
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sizeof (struct fixup));
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f->next = linux_hash_table (info)->fixup_list;
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linux_hash_table (info)->fixup_list = f;
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f->builtin = builtin;
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++linux_hash_table (info)->fixup_count;
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/* We come here once we realize that we are going to link to a shared
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library. We need to create a special section that contains the
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fixup table, and we ultimately need to add a pointer to this into
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the set vector for SHARABLE_CONFLICTS. At this point we do not
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know the size of the section, but that's OK - we just need to
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create it for now. */
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linux_link_create_dynamic_sections (abfd, info)
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struct bfd_link_info *info ATTRIBUTE_UNUSED;
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register asection *s;
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/* Note that we set the SEC_IN_MEMORY flag. */
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flags = SEC_ALLOC | SEC_LOAD | SEC_HAS_CONTENTS | SEC_IN_MEMORY;
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/* We choose to use the name ".linux-dynamic" for the fixup table.
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s = bfd_make_section (abfd, ".linux-dynamic");
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|| ! bfd_set_section_flags (abfd, s, flags)
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|| ! bfd_set_section_alignment (abfd, s, 2))
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/* Function to add a single symbol to the linker hash table. This is
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a wrapper around _bfd_generic_link_add_one_symbol which handles the
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tweaking needed for dynamic linking support. */
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linux_add_one_symbol (info, abfd, name, flags, section, value, string,
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copy, collect, hashp)
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struct bfd_link_info *info;
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struct bfd_link_hash_entry **hashp;
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struct linux_link_hash_entry *h;
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/* Look up and see if we already have this symbol in the hash table.
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If we do, and the defining entry is from a shared library, we
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need to create the dynamic sections.
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FIXME: What if abfd->xvec != info->hash->creator? We may want to
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be able to link Linux a.out and ELF objects together, but serious
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confusion is possible. */
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if (! info->relocateable
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&& linux_hash_table (info)->dynobj == NULL
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&& strcmp (name, SHARABLE_CONFLICTS) == 0
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&& (flags & BSF_CONSTRUCTOR) != 0
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&& abfd->xvec == info->hash->creator)
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if (! linux_link_create_dynamic_sections (abfd, info))
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linux_hash_table (info)->dynobj = abfd;
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if (bfd_is_abs_section (section)
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&& abfd->xvec == info->hash->creator)
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h = linux_link_hash_lookup (linux_hash_table (info), name, false,
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&& (h->root.root.type == bfd_link_hash_defined
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|| h->root.root.type == bfd_link_hash_defweak))
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*hashp = (struct bfd_link_hash_entry *) h;
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f = new_fixup (info, h, value, ! IS_PLT_SYM (name));
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f->jump = IS_PLT_SYM (name);
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/* Do the usual procedure for adding a symbol. */
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if (! _bfd_generic_link_add_one_symbol (info, abfd, name, flags, section,
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value, string, copy, collect,
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/* Insert a pointer to our table in the set vector. The dynamic
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linker requires this information */
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/* Here we do our special thing to add the pointer to the
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dynamic section in the SHARABLE_CONFLICTS set vector. */
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s = bfd_get_section_by_name (linux_hash_table (info)->dynobj,
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BFD_ASSERT (s != NULL);
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if (! (_bfd_generic_link_add_one_symbol
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(info, linux_hash_table (info)->dynobj, SHARABLE_CONFLICTS,
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BSF_GLOBAL | BSF_CONSTRUCTOR, s, (bfd_vma) 0, NULL,
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false, false, NULL)))
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/* We will crawl the hash table and come here for every global symbol.
421
We will examine each entry and see if there are indications that we
422
need to add a fixup. There are two possible cases - one is where
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you have duplicate definitions of PLT or GOT symbols - these will
424
have already been caught and added as "builtin" fixups. If we find
425
that the corresponding non PLT/GOT symbol is also present, we
426
convert it to a regular fixup instead.
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This function is called via linux_link_hash_traverse. */
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linux_tally_symbols (h, data)
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struct linux_link_hash_entry *h;
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struct bfd_link_info *info = (struct bfd_link_info *) data;
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struct fixup *f, *f1;
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struct linux_link_hash_entry *h1, *h2;
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if (h->root.root.type == bfd_link_hash_warning)
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h = (struct linux_link_hash_entry *) h->root.root.u.i.link;
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if (h->root.root.type == bfd_link_hash_undefined
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&& strncmp (h->root.root.root.string, NEEDS_SHRLIB,
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sizeof NEEDS_SHRLIB - 1) == 0)
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name = h->root.root.root.string + sizeof NEEDS_SHRLIB - 1;
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p = strrchr (name, '_');
455
alloc = (char *) bfd_malloc ((bfd_size_type) strlen (name) + 1);
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if (p == NULL || alloc == NULL)
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(*_bfd_error_handler) (_("Output file requires shared library `%s'\n"),
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strcpy (alloc, name);
463
p = strrchr (alloc, '_');
465
(*_bfd_error_handler)
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(_("Output file requires shared library `%s.so.%s'\n"),
474
/* If this symbol is not a PLT/GOT, we do not even need to look at it */
475
is_plt = IS_PLT_SYM (h->root.root.root.string);
477
if (is_plt || IS_GOT_SYM (h->root.root.root.string))
479
/* Look up this symbol twice. Once just as a regular lookup,
480
and then again following all of the indirect links until we
481
reach a real symbol. */
482
h1 = linux_link_hash_lookup (linux_hash_table (info),
483
(h->root.root.root.string
484
+ sizeof PLT_REF_PREFIX - 1),
486
/* h2 does not follow indirect symbols. */
487
h2 = linux_link_hash_lookup (linux_hash_table (info),
488
(h->root.root.root.string
489
+ sizeof PLT_REF_PREFIX - 1),
490
false, false, false);
492
/* The real symbol must exist but if it is also an ABS symbol,
493
there is no need to have a fixup. This is because they both
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came from the same library. If on the other hand, we had to
495
use an indirect symbol to get to the real symbol, we add the
496
fixup anyway, since there are cases where these symbols come
497
from different shared libraries */
499
&& (((h1->root.root.type == bfd_link_hash_defined
500
|| h1->root.root.type == bfd_link_hash_defweak)
501
&& ! bfd_is_abs_section (h1->root.root.u.def.section))
502
|| h2->root.root.type == bfd_link_hash_indirect))
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/* See if there is a "builtin" fixup already present
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involving this symbol. If so, convert it to a regular
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fixup. In the end, this relaxes some of the requirements
507
about the order of performing fixups. */
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for (f1 = linux_hash_table (info)->fixup_list;
513
if ((f1->h != h && f1->h != h1)
514
|| (! f1->builtin && ! f1->jump))
519
&& bfd_is_abs_section (h->root.root.u.def.section))
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f = new_fixup (info, h1, f1->h->root.root.u.def.value, 0);
530
&& bfd_is_abs_section (h->root.root.u.def.section))
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f = new_fixup (info, h1, h->root.root.u.def.value, 0);
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/* FIXME: No way to return error. */
542
/* Quick and dirty way of stripping these symbols from the
544
if (bfd_is_abs_section (h->root.root.u.def.section))
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h->root.written = true;
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/* This is called to set the size of the .linux-dynamic section is.
552
It is called by the Linux linker emulation before_allocation
553
routine. We have finished reading all of the input files, and now
554
we just scan the hash tables to find out how many additional fixups
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bfd_i386linux_size_dynamic_sections (output_bfd, info)
560
struct bfd_link_info *info;
565
if (output_bfd->xvec != &MY(vec))
568
/* First find the fixups... */
569
linux_link_hash_traverse (linux_hash_table (info),
573
/* If there are builtin fixups, leave room for a marker. This is
574
used by the dynamic linker so that it knows that all that follow
575
are builtin fixups instead of regular fixups. */
576
for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
580
++linux_hash_table (info)->fixup_count;
581
++linux_hash_table (info)->local_builtins;
586
if (linux_hash_table (info)->dynobj == NULL)
588
if (linux_hash_table (info)->fixup_count > 0)
593
/* Allocate memory for our fixup table. We will fill it in later. */
594
s = bfd_get_section_by_name (linux_hash_table (info)->dynobj,
598
s->_raw_size = linux_hash_table (info)->fixup_count + 1;
600
s->contents = (bfd_byte *) bfd_zalloc (output_bfd, s->_raw_size);
601
if (s->contents == NULL)
608
/* We come here once we are ready to actually write the fixup table to
609
the output file. Scan the fixup tables and so forth and generate
610
the stuff we need. */
613
linux_finish_dynamic_link (output_bfd, info)
615
struct bfd_link_info *info;
617
asection *s, *os, *is;
618
bfd_byte *fixup_table;
619
struct linux_link_hash_entry *h;
621
unsigned int new_addr;
623
unsigned int fixups_written;
625
if (linux_hash_table (info)->dynobj == NULL)
628
s = bfd_get_section_by_name (linux_hash_table (info)->dynobj,
630
BFD_ASSERT (s != NULL);
631
os = s->output_section;
634
#ifdef LINUX_LINK_DEBUG
635
printf ("Fixup table file offset: %x VMA: %x\n",
636
os->filepos + s->output_offset,
637
os->vma + s->output_offset);
640
fixup_table = s->contents;
641
bfd_put_32 (output_bfd,
642
(bfd_vma) linux_hash_table (info)->fixup_count, fixup_table);
645
/* Fill in fixup table. */
646
for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
651
if (f->h->root.root.type != bfd_link_hash_defined
652
&& f->h->root.root.type != bfd_link_hash_defweak)
654
(*_bfd_error_handler)
655
(_("Symbol %s not defined for fixups\n"),
656
f->h->root.root.root.string);
660
is = f->h->root.root.u.def.section;
661
section_offset = is->output_section->vma + is->output_offset;
662
new_addr = f->h->root.root.u.def.value + section_offset;
664
#ifdef LINUX_LINK_DEBUG
665
printf ("Fixup(%d) %s: %x %x\n",f->jump, f->h->root.root.string,
671
/* Relative address */
672
new_addr = new_addr - (f->value + 5);
673
bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
675
bfd_put_32 (output_bfd, f->value + 1, fixup_table);
680
bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
682
bfd_put_32 (output_bfd, f->value, fixup_table);
688
if (linux_hash_table (info)->local_builtins != 0)
690
/* Special marker so we know to switch to the other type of fixup */
691
bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
693
bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
696
for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
701
if (f->h->root.root.type != bfd_link_hash_defined
702
&& f->h->root.root.type != bfd_link_hash_defweak)
704
(*_bfd_error_handler)
705
(_("Symbol %s not defined for fixups\n"),
706
f->h->root.root.root.string);
710
is = f->h->root.root.u.def.section;
711
section_offset = is->output_section->vma + is->output_offset;
712
new_addr = f->h->root.root.u.def.value + section_offset;
714
#ifdef LINUX_LINK_DEBUG
715
printf ("Fixup(B) %s: %x %x\n", f->h->root.root.string,
719
bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
721
bfd_put_32 (output_bfd, f->value, fixup_table);
727
if (linux_hash_table (info)->fixup_count != fixups_written)
729
(*_bfd_error_handler) (_("Warning: fixup count mismatch\n"));
730
while (linux_hash_table (info)->fixup_count > fixups_written)
732
bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
734
bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
740
h = linux_link_hash_lookup (linux_hash_table (info),
741
"__BUILTIN_FIXUPS__",
742
false, false, false);
745
&& (h->root.root.type == bfd_link_hash_defined
746
|| h->root.root.type == bfd_link_hash_defweak))
748
is = h->root.root.u.def.section;
749
section_offset = is->output_section->vma + is->output_offset;
750
new_addr = h->root.root.u.def.value + section_offset;
752
#ifdef LINUX_LINK_DEBUG
753
printf ("Builtin fixup table at %x\n", new_addr);
756
bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
759
bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
761
if (bfd_seek (output_bfd, (file_ptr) (os->filepos + s->output_offset),
765
if (bfd_bwrite ((PTR) s->contents, s->_raw_size, output_bfd) != s->_raw_size)
771
#define MY_bfd_link_hash_table_create linux_link_hash_table_create
772
#define MY_add_one_symbol linux_add_one_symbol
773
#define MY_finish_dynamic_link linux_finish_dynamic_link
775
#define MY_zmagic_contiguous 1
777
#include "aout-target.h"
added
removed
binutils/bfd/i386linux.c
