diff options
Diffstat (limited to 'binutils-2.25/bfd/i386linux.c')
| -rw-r--r-- | binutils-2.25/bfd/i386linux.c | 735 |
1 files changed, 735 insertions, 0 deletions
diff --git a/binutils-2.25/bfd/i386linux.c b/binutils-2.25/bfd/i386linux.c new file mode 100644 index 00000000..65ae5c9c --- /dev/null +++ b/binutils-2.25/bfd/i386linux.c @@ -0,0 +1,735 @@ +/* BFD back-end for linux flavored i386 a.out binaries. + Copyright 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2001, 2002, 2003, + 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 + Free Software Foundation, Inc. + + This file is part of BFD, the Binary File Descriptor library. + + 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 3 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., 51 Franklin Street - Fifth Floor, Boston, + MA 02110-1301, USA. */ + +#define TARGET_PAGE_SIZE 4096 +#define ZMAGIC_DISK_BLOCK_SIZE 1024 +#define SEGMENT_SIZE TARGET_PAGE_SIZE +#define TEXT_START_ADDR 0x0 + +#define MACHTYPE_OK(mtype) ((mtype) == M_386 || (mtype) == M_UNKNOWN) + +#include "sysdep.h" +#include "bfd.h" +#include "libbfd.h" +#include "aout/aout64.h" +#include "aout/stab_gnu.h" +#include "aout/ar.h" +#include "libaout.h" /* BFD a.out internal data structures */ + +#define DEFAULT_ARCH bfd_arch_i386 + +/* Do not "beautify" the CONCAT* macro args. Traditional C will not + remove whitespace added here, and thus will fail to concatenate + the tokens. */ +#define MY(OP) CONCAT2 (i386linux_,OP) +#define TARGETNAME "a.out-i386-linux" + +extern const bfd_target MY(vec); + +/* We always generate QMAGIC files in preference to ZMAGIC files. It + would be possible to make this a linker option, if that ever + becomes important. */ + +static void MY_final_link_callback + (bfd *, file_ptr *, file_ptr *, file_ptr *); +static bfd_boolean i386linux_bfd_final_link + (bfd *, struct bfd_link_info *); +static bfd_boolean i386linux_write_object_contents (bfd *); + +static bfd_boolean +i386linux_bfd_final_link (bfd *abfd, struct bfd_link_info *info) +{ + obj_aout_subformat (abfd) = q_magic_format; + return NAME(aout,final_link) (abfd, info, MY_final_link_callback); +} + +#define MY_bfd_final_link i386linux_bfd_final_link + +/* Set the machine type correctly. */ + +static bfd_boolean +i386linux_write_object_contents (bfd *abfd) +{ + struct external_exec exec_bytes; + struct internal_exec *execp = exec_hdr (abfd); + + N_SET_MACHTYPE (*execp, M_386); + + obj_reloc_entry_size (abfd) = RELOC_STD_SIZE; + + WRITE_HEADERS(abfd, execp); + + return TRUE; +} + +#define MY_write_object_contents i386linux_write_object_contents + +/* Code to link against Linux a.out shared libraries. */ + +/* See if a symbol name is a reference to the global offset table. */ + +#ifndef GOT_REF_PREFIX +#define GOT_REF_PREFIX "__GOT_" +#endif + +#define IS_GOT_SYM(name) (CONST_STRNEQ (name, GOT_REF_PREFIX)) + +/* See if a symbol name is a reference to the procedure linkage table. */ + +#ifndef PLT_REF_PREFIX +#define PLT_REF_PREFIX "__PLT_" +#endif + +#define IS_PLT_SYM(name) (CONST_STRNEQ (name, PLT_REF_PREFIX)) + +/* This string is used to generate specialized error messages. */ + +#ifndef NEEDS_SHRLIB +#define NEEDS_SHRLIB "__NEEDS_SHRLIB_" +#endif + +/* This special symbol is a set vector that contains a list of + pointers to fixup tables. It will be present in any dynamically + linked file. The linker generated fixup table should also be added + to the list, and it should always appear in the second slot (the + first one is a dummy with a magic number that is defined in + crt0.o). */ + +#ifndef SHARABLE_CONFLICTS +#define SHARABLE_CONFLICTS "__SHARABLE_CONFLICTS__" +#endif + +/* We keep a list of fixups. The terminology is a bit strange, but + each fixup contains two 32 bit numbers. A regular fixup contains + an address and a pointer, and at runtime we should store the + address at the location pointed to by the pointer. A builtin fixup + contains two pointers, and we should read the address using one + pointer and store it at the location pointed to by the other + pointer. Builtin fixups come into play when we have duplicate + __GOT__ symbols for the same variable. The builtin fixup will copy + the GOT pointer from one over into the other. */ + +struct fixup +{ + struct fixup *next; + struct linux_link_hash_entry *h; + bfd_vma value; + + /* Nonzero if this is a jump instruction that needs to be fixed, + zero if this is just a pointer */ + char jump; + + char builtin; +}; + +/* We don't need a special hash table entry structure, but we do need + to keep some information between linker passes, so we use a special + hash table. */ + +struct linux_link_hash_entry +{ + struct aout_link_hash_entry root; +}; + +struct linux_link_hash_table +{ + struct aout_link_hash_table root; + + /* First dynamic object found in link. */ + bfd *dynobj; + + /* Number of fixups. */ + size_t fixup_count; + + /* Number of builtin fixups. */ + size_t local_builtins; + + /* List of fixups. */ + struct fixup *fixup_list; +}; + +/* Routine to create an entry in an Linux link hash table. */ + +static struct bfd_hash_entry * +linux_link_hash_newfunc (struct bfd_hash_entry *entry, + struct bfd_hash_table *table, + const char *string) +{ + struct linux_link_hash_entry *ret = (struct linux_link_hash_entry *) entry; + + /* Allocate the structure if it has not already been allocated by a + subclass. */ + if (ret == (struct linux_link_hash_entry *) NULL) + ret = ((struct linux_link_hash_entry *) + bfd_hash_allocate (table, sizeof (struct linux_link_hash_entry))); + if (ret == NULL) + return (struct bfd_hash_entry *) ret; + + /* Call the allocation method of the superclass. */ + ret = ((struct linux_link_hash_entry *) + NAME(aout,link_hash_newfunc) ((struct bfd_hash_entry *) ret, + table, string)); + if (ret != NULL) + { + /* Set local fields; there aren't any. */ + } + + return (struct bfd_hash_entry *) ret; +} + +/* Create a Linux link hash table. */ + +static struct bfd_link_hash_table * +linux_link_hash_table_create (bfd *abfd) +{ + struct linux_link_hash_table *ret; + bfd_size_type amt = sizeof (struct linux_link_hash_table); + + ret = (struct linux_link_hash_table *) bfd_zmalloc (amt); + if (ret == (struct linux_link_hash_table *) NULL) + return (struct bfd_link_hash_table *) NULL; + if (!NAME(aout,link_hash_table_init) (&ret->root, abfd, + linux_link_hash_newfunc, + sizeof (struct linux_link_hash_entry))) + { + free (ret); + return (struct bfd_link_hash_table *) NULL; + } + + return &ret->root.root; +} + +/* Look up an entry in a Linux link hash table. */ + +#define linux_link_hash_lookup(table, string, create, copy, follow) \ + ((struct linux_link_hash_entry *) \ + aout_link_hash_lookup (&(table)->root, (string), (create), (copy),\ + (follow))) + +/* Traverse a Linux link hash table. */ + +#define linux_link_hash_traverse(table, func, info) \ + (aout_link_hash_traverse \ + (&(table)->root, \ + (bfd_boolean (*) (struct aout_link_hash_entry *, void *)) (func), \ + (info))) + +/* Get the Linux link hash table from the info structure. This is + just a cast. */ + +#define linux_hash_table(p) ((struct linux_link_hash_table *) ((p)->hash)) + +/* Store the information for a new fixup. */ + +static struct fixup * +new_fixup (struct bfd_link_info *info, + struct linux_link_hash_entry *h, + bfd_vma value, + int builtin) +{ + struct fixup *f; + + f = (struct fixup *) bfd_hash_allocate (&info->hash->table, + sizeof (struct fixup)); + if (f == NULL) + return f; + f->next = linux_hash_table (info)->fixup_list; + linux_hash_table (info)->fixup_list = f; + f->h = h; + f->value = value; + f->builtin = builtin; + f->jump = 0; + ++linux_hash_table (info)->fixup_count; + return f; +} + +/* We come here once we realize that we are going to link to a shared + library. We need to create a special section that contains the + fixup table, and we ultimately need to add a pointer to this into + the set vector for SHARABLE_CONFLICTS. At this point we do not + know the size of the section, but that's OK - we just need to + create it for now. */ + +static bfd_boolean +linux_link_create_dynamic_sections (bfd *abfd, + struct bfd_link_info *info ATTRIBUTE_UNUSED) +{ + flagword flags; + asection *s; + + /* Note that we set the SEC_IN_MEMORY flag. */ + flags = SEC_ALLOC | SEC_LOAD | SEC_HAS_CONTENTS | SEC_IN_MEMORY; + + /* We choose to use the name ".linux-dynamic" for the fixup table. + Why not? */ + s = bfd_make_section_with_flags (abfd, ".linux-dynamic", flags); + if (s == NULL + || ! bfd_set_section_alignment (abfd, s, 2)) + return FALSE; + s->size = 0; + s->contents = 0; + + return TRUE; +} + +/* Function to add a single symbol to the linker hash table. This is + a wrapper around _bfd_generic_link_add_one_symbol which handles the + tweaking needed for dynamic linking support. */ + +static bfd_boolean +linux_add_one_symbol (struct bfd_link_info *info, + bfd *abfd, + const char *name, + flagword flags, + asection *section, + bfd_vma value, + const char *string, + bfd_boolean copy, + bfd_boolean collect, + struct bfd_link_hash_entry **hashp) +{ + struct linux_link_hash_entry *h; + bfd_boolean insert; + + /* Look up and see if we already have this symbol in the hash table. + If we do, and the defining entry is from a shared library, we + need to create the dynamic sections. + + FIXME: What if abfd->xvec != info->output_bfd->xvec? We may + want to be able to link Linux a.out and ELF objects together, + but serious confusion is possible. */ + + insert = FALSE; + + if (! info->relocatable + && linux_hash_table (info)->dynobj == NULL + && strcmp (name, SHARABLE_CONFLICTS) == 0 + && (flags & BSF_CONSTRUCTOR) != 0 + && abfd->xvec == info->output_bfd->xvec) + { + if (! linux_link_create_dynamic_sections (abfd, info)) + return FALSE; + linux_hash_table (info)->dynobj = abfd; + insert = TRUE; + } + + if (bfd_is_abs_section (section) + && abfd->xvec == info->output_bfd->xvec) + { + h = linux_link_hash_lookup (linux_hash_table (info), name, FALSE, + FALSE, FALSE); + if (h != NULL + && (h->root.root.type == bfd_link_hash_defined + || h->root.root.type == bfd_link_hash_defweak)) + { + struct fixup *f; + + if (hashp != NULL) + *hashp = (struct bfd_link_hash_entry *) h; + + f = new_fixup (info, h, value, ! IS_PLT_SYM (name)); + if (f == NULL) + return FALSE; + f->jump = IS_PLT_SYM (name); + + return TRUE; + } + } + + /* Do the usual procedure for adding a symbol. */ + if (! _bfd_generic_link_add_one_symbol (info, abfd, name, flags, section, + value, string, copy, collect, + hashp)) + return FALSE; + + /* Insert a pointer to our table in the set vector. The dynamic + linker requires this information */ + if (insert) + { + asection *s; + + /* Here we do our special thing to add the pointer to the + dynamic section in the SHARABLE_CONFLICTS set vector. */ + s = bfd_get_section_by_name (linux_hash_table (info)->dynobj, + ".linux-dynamic"); + BFD_ASSERT (s != NULL); + + if (! (_bfd_generic_link_add_one_symbol + (info, linux_hash_table (info)->dynobj, SHARABLE_CONFLICTS, + BSF_GLOBAL | BSF_CONSTRUCTOR, s, (bfd_vma) 0, NULL, + FALSE, FALSE, NULL))) + return FALSE; + } + + return TRUE; +} + +/* We will crawl the hash table and come here for every global symbol. + We will examine each entry and see if there are indications that we + need to add a fixup. There are two possible cases - one is where + you have duplicate definitions of PLT or GOT symbols - these will + have already been caught and added as "builtin" fixups. If we find + that the corresponding non PLT/GOT symbol is also present, we + convert it to a regular fixup instead. + + This function is called via linux_link_hash_traverse. */ + +static bfd_boolean +linux_tally_symbols (struct linux_link_hash_entry *h, void * data) +{ + struct bfd_link_info *info = (struct bfd_link_info *) data; + struct fixup *f, *f1; + int is_plt; + struct linux_link_hash_entry *h1, *h2; + bfd_boolean exists; + + if (h->root.root.type == bfd_link_hash_undefined + && CONST_STRNEQ (h->root.root.root.string, NEEDS_SHRLIB)) + { + const char *name; + char *p; + char *alloc = NULL; + + name = h->root.root.root.string + sizeof NEEDS_SHRLIB - 1; + p = strrchr (name, '_'); + if (p != NULL) + alloc = (char *) bfd_malloc ((bfd_size_type) strlen (name) + 1); + + if (p == NULL || alloc == NULL) + (*_bfd_error_handler) (_("Output file requires shared library `%s'\n"), + name); + else + { + strcpy (alloc, name); + p = strrchr (alloc, '_'); + *p++ = '\0'; + (*_bfd_error_handler) + (_("Output file requires shared library `%s.so.%s'\n"), + alloc, p); + free (alloc); + } + + abort (); + } + + /* If this symbol is not a PLT/GOT, we do not even need to look at it */ + is_plt = IS_PLT_SYM (h->root.root.root.string); + + if (is_plt || IS_GOT_SYM (h->root.root.root.string)) + { + /* Look up this symbol twice. Once just as a regular lookup, + and then again following all of the indirect links until we + reach a real symbol. */ + h1 = linux_link_hash_lookup (linux_hash_table (info), + (h->root.root.root.string + + sizeof PLT_REF_PREFIX - 1), + FALSE, FALSE, TRUE); + /* h2 does not follow indirect symbols. */ + h2 = linux_link_hash_lookup (linux_hash_table (info), + (h->root.root.root.string + + sizeof PLT_REF_PREFIX - 1), + FALSE, FALSE, FALSE); + + /* The real symbol must exist but if it is also an ABS symbol, + there is no need to have a fixup. This is because they both + came from the same library. If on the other hand, we had to + use an indirect symbol to get to the real symbol, we add the + fixup anyway, since there are cases where these symbols come + from different shared libraries */ + if (h1 != NULL + && (((h1->root.root.type == bfd_link_hash_defined + || h1->root.root.type == bfd_link_hash_defweak) + && ! bfd_is_abs_section (h1->root.root.u.def.section)) + || h2->root.root.type == bfd_link_hash_indirect)) + { + /* See if there is a "builtin" fixup already present + involving this symbol. If so, convert it to a regular + fixup. In the end, this relaxes some of the requirements + about the order of performing fixups. */ + exists = FALSE; + for (f1 = linux_hash_table (info)->fixup_list; + f1 != NULL; + f1 = f1->next) + { + if ((f1->h != h && f1->h != h1) + || (! f1->builtin && ! f1->jump)) + continue; + if (f1->h == h1) + exists = TRUE; + if (! exists + && bfd_is_abs_section (h->root.root.u.def.section)) + { + f = new_fixup (info, h1, f1->h->root.root.u.def.value, 0); + f->jump = is_plt; + } + f1->h = h1; + f1->jump = is_plt; + f1->builtin = 0; + exists = TRUE; + } + if (! exists + && bfd_is_abs_section (h->root.root.u.def.section)) + { + f = new_fixup (info, h1, h->root.root.u.def.value, 0); + if (f == NULL) + { + /* FIXME: No way to return error. */ + abort (); + } + f->jump = is_plt; + } + } + + /* Quick and dirty way of stripping these symbols from the + symtab. */ + if (bfd_is_abs_section (h->root.root.u.def.section)) + h->root.written = TRUE; + } + + return TRUE; +} + +/* This is called to set the size of the .linux-dynamic section is. + It is called by the Linux linker emulation before_allocation + routine. We have finished reading all of the input files, and now + we just scan the hash tables to find out how many additional fixups + are required. */ + +bfd_boolean +bfd_i386linux_size_dynamic_sections (bfd *output_bfd, + struct bfd_link_info *info) +{ + struct fixup *f; + asection *s; + + if (output_bfd->xvec != &MY(vec)) + return TRUE; + + /* First find the fixups... */ + linux_link_hash_traverse (linux_hash_table (info), + linux_tally_symbols, + info); + + /* If there are builtin fixups, leave room for a marker. This is + used by the dynamic linker so that it knows that all that follow + are builtin fixups instead of regular fixups. */ + for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next) + { + if (f->builtin) + { + ++linux_hash_table (info)->fixup_count; + ++linux_hash_table (info)->local_builtins; + break; + } + } + + if (linux_hash_table (info)->dynobj == NULL) + { + if (linux_hash_table (info)->fixup_count > 0) + abort (); + return TRUE; + } + + /* Allocate memory for our fixup table. We will fill it in later. */ + s = bfd_get_section_by_name (linux_hash_table (info)->dynobj, + ".linux-dynamic"); + if (s != NULL) + { + s->size = linux_hash_table (info)->fixup_count + 1; + s->size *= 8; + s->contents = (bfd_byte *) bfd_zalloc (output_bfd, s->size); + if (s->contents == NULL) + return FALSE; + } + + return TRUE; +} + +/* We come here once we are ready to actually write the fixup table to + the output file. Scan the fixup tables and so forth and generate + the stuff we need. */ + +static bfd_boolean +linux_finish_dynamic_link (bfd *output_bfd, + struct bfd_link_info *info) +{ + asection *s, *os, *is; + bfd_byte *fixup_table; + struct linux_link_hash_entry *h; + struct fixup *f; + unsigned int new_addr; + int section_offset; + unsigned int fixups_written; + + if (linux_hash_table (info)->dynobj == NULL) + return TRUE; + + s = bfd_get_section_by_name (linux_hash_table (info)->dynobj, + ".linux-dynamic"); + BFD_ASSERT (s != NULL); + os = s->output_section; + fixups_written = 0; + +#ifdef LINUX_LINK_DEBUG + printf ("Fixup table file offset: %x VMA: %x\n", + os->filepos + s->output_offset, + os->vma + s->output_offset); +#endif + + fixup_table = s->contents; + bfd_put_32 (output_bfd, + (bfd_vma) linux_hash_table (info)->fixup_count, fixup_table); + fixup_table += 4; + + /* Fill in fixup table. */ + for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next) + { + if (f->builtin) + continue; + + if (f->h->root.root.type != bfd_link_hash_defined + && f->h->root.root.type != bfd_link_hash_defweak) + { + (*_bfd_error_handler) + (_("Symbol %s not defined for fixups\n"), + f->h->root.root.root.string); + continue; + } + + is = f->h->root.root.u.def.section; + section_offset = is->output_section->vma + is->output_offset; + new_addr = f->h->root.root.u.def.value + section_offset; + +#ifdef LINUX_LINK_DEBUG + printf ("Fixup(%d) %s: %x %x\n",f->jump, f->h->root.root.string, + new_addr, f->value); +#endif + + if (f->jump) + { + /* Relative address */ + new_addr = new_addr - (f->value + 5); + bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table); + fixup_table += 4; + bfd_put_32 (output_bfd, f->value + 1, fixup_table); + fixup_table += 4; + } + else + { + bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table); + fixup_table += 4; + bfd_put_32 (output_bfd, f->value, fixup_table); + fixup_table += 4; + } + ++fixups_written; + } + + if (linux_hash_table (info)->local_builtins != 0) + { + /* Special marker so we know to switch to the other type of fixup */ + bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table); + fixup_table += 4; + bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table); + fixup_table += 4; + ++fixups_written; + for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next) + { + if (! f->builtin) + continue; + + if (f->h->root.root.type != bfd_link_hash_defined + && f->h->root.root.type != bfd_link_hash_defweak) + { + (*_bfd_error_handler) + (_("Symbol %s not defined for fixups\n"), + f->h->root.root.root.string); + continue; + } + + is = f->h->root.root.u.def.section; + section_offset = is->output_section->vma + is->output_offset; + new_addr = f->h->root.root.u.def.value + section_offset; + +#ifdef LINUX_LINK_DEBUG + printf ("Fixup(B) %s: %x %x\n", f->h->root.root.string, + new_addr, f->value); +#endif + + bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table); + fixup_table += 4; + bfd_put_32 (output_bfd, f->value, fixup_table); + fixup_table += 4; + ++fixups_written; + } + } + + if (linux_hash_table (info)->fixup_count != fixups_written) + { + (*_bfd_error_handler) (_("Warning: fixup count mismatch\n")); + while (linux_hash_table (info)->fixup_count > fixups_written) + { + bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table); + fixup_table += 4; + bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table); + fixup_table += 4; + ++fixups_written; + } + } + + h = linux_link_hash_lookup (linux_hash_table (info), + "__BUILTIN_FIXUPS__", + FALSE, FALSE, FALSE); + + if (h != NULL + && (h->root.root.type == bfd_link_hash_defined + || h->root.root.type == bfd_link_hash_defweak)) + { + is = h->root.root.u.def.section; + section_offset = is->output_section->vma + is->output_offset; + new_addr = h->root.root.u.def.value + section_offset; + +#ifdef LINUX_LINK_DEBUG + printf ("Builtin fixup table at %x\n", new_addr); +#endif + + bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table); + } + else + bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table); + + if (bfd_seek (output_bfd, (file_ptr) (os->filepos + s->output_offset), + SEEK_SET) != 0) + return FALSE; + + if (bfd_bwrite (s->contents, s->size, output_bfd) != s->size) + return FALSE; + + return TRUE; +} + +#define MY_bfd_link_hash_table_create linux_link_hash_table_create +#define MY_add_one_symbol linux_add_one_symbol +#define MY_finish_dynamic_link linux_finish_dynamic_link + +#define MY_zmagic_contiguous 1 + +#include "aout-target.h" |