Fix the ELF linker to not require an interpreter if no dynamic

objects were seen, even when linking PIC code.
	* libelf.h (ELF_LINK_HASH_NEEDS_PLT): Define.
	(struct elf_link_hash_table): Add field dynamic_sections_created.
	* elfcode.h (elf_link_record_dynamic_symbol): Create dynstr if it
	doesn't already exist.
	(elf_link_add_object_symbols): Create dynamic sections based on
	dynamic_sections_created field, not dynobj field.  Don't bother to
	set dynobj.
	(elf_link_create_dynamic_sections): If dynamic sections were
	already created, don't do anything.  If dynobj is already set, use
	it; otherwise, set it to the bfd argument.  Don't initialize
	dynsymcount.  Only create dynstr if it does not exist.  Set
	dynamic_sections_created to true.
	(NAME(bfd_elf,size_dynamic_sections)): Skip most of this function
	if no dynamic objects were seen.
	(elf_adjust_dynamic_symbol): If a symbol has the
	ELF_LINK_HASH_NEEDS_PLT flag set, let the backend adjust it.
	(elf_bfd_final_link): Change most decisions based on dynobj to
	check dynamic_sections_created instead.
	(elf_link_output_extsym): Only handle dynamic symbols if a dynamic
	object was seen.
	* elf.c (_bfd_elf_link_hash_table_init): Initialize new field
	dynamic_sections_created.  Set dynsymcount to 1, not 0.
	* elf32-i386.c (elf_i386_create_dynamic_sections): Call
	elf_i386_create_got_section rather than creating the .got and
	.got.plt sections.
	(elf_i386_create_got_section): New static function.
	(elf_i386_check_relocs): Just call elf_i386_create_got_section if
	a GOT table is needed, not bfd_elf32_link_create_dynamic_sections.
	Only create the .rel.got section, and only make space for a reloc,
	for a global symbol or when generating a shared object.  For a
	R_386_PLT32 reloc, just set the	ELF_LINK_HASH_NEEDS_PLT flag.
	(elf_i386_adjust_dynamic_symbol): Rework initial assertion to
	permit ELF_LINK_HASH_NEEDS_PLT non dynamic symbols.  Create a
	procedure linkage table entry for such symbols.  But, if no
	dynamic objects were seen, never create a PLT entry.
	(elf_i386_size_dynamic_sections): If no dynamic objects were seen,
	skip most of this function, and force the size of the .rel.got
	section to zero.
	(elf_i386_relocate_section): For a R_386_GOT32 reloc against a global
	symbol when no dynamic object was seen, initialize the contents of
	the .got section.  For a R_386_GOT32 against a local symbol, only
	create a R_386_RELATIVE reloc when generating a shared object.
	Treat a R_386_PLT32 reloc against a symbol for which we did not
	create a PLT entry as a R_386_PC32 reloc.
	(elf_i386_finish_dynamic_sections): Only fiddle with the dynamic
	entries and the PLT if we saw a dynamic object.
	* elf32-sparc.c (elf_sparc_howto_table): Fix R_SPARC_PC22 by
	setting rightshift to 10.  Fix R_SPARC_WPLT20 by setting
	rightshift to 2, size to 2, bitsize to 30, and dst_mask to
	0x3fffffff.
	(elf32_sparc_create_dynamic_sections): Don't set the size of the
	.plt section.  Call elf32_sparc_create_got_section rather than
	creating the .got section.
	(elf32_sparc_check_relocs): Call elf32_sparc_create_got_section if
	a GOT table is needed, not bfd_elf32_link_create_dynamic_sections.
	Only create the .rela.got section, and only make space for a
	reloc, for a global symbol or when generating a shared object.
	Set the alignment of the .rela.got section to 2.  For a
	R_SPARC_WPLT30 reloc, just set the ELF_LINK_HASH_NEEDS_PLT flag.
	(elf32_sparc_adjust_dynamic_symbol): Rework initial assertion to
	permit ELF_LINK_HASH_NEDS_PLT non dynamic symbols.  Create a
	procedure linkage table for such symbols.  But, if no dynamic
	objects were seen, never create a PLT entry.  Initialize the size
	of the .plt section.
	(elf32_sparc_size_dynamic_sections): If no dynamic objects were
	seen, skip most of this function, and force the size of the
	.rela.got section to zero.  Strip empty reloc sections, and strip
	an empty .plt section.
	(elf32_sparc_relocate_section): For a GOT reloc against a global
	symbol when no dynamic object was seen, initialize the contents of
	the .got section.  For a GOT reloc against a local symbol, only
	create a R_SPARC_RELATIVE reloc when generating a shared object.
	Treat a R_SPARC_WPLT30 reloc against a symbol for which we did not
	create a PLT entry as a R_SPARC_WDISP30 reloc.
	(elf32_sparc_finish_dynamic_sections): Only fiddle with the
	dynamic entries and the PLT if we saw a dynamic object.
This commit is contained in:
Ian Lance Taylor
1994-10-21 22:00:18 +00:00
parent 6b55e5e3b9
commit 12662be4fe
5 changed files with 944 additions and 610 deletions

View File

@ -3868,21 +3868,36 @@ elf_link_add_archive_symbols (abfd, info)
/* Record a new dynamic symbol. We record the dynamic symbols as we
read the input files, since we need to have a list of all of them
before we can determine the final sizes of the output sections. */
before we can determine the final sizes of the output sections.
Note that we may actually call this function even though we are not
going to output any dynamic symbols; in some cases we know that a
symbol should be in the dynamic symbol table, but only if there is
one. */
INLINE boolean
boolean
elf_link_record_dynamic_symbol (info, h)
struct bfd_link_info *info;
struct elf_link_hash_entry *h;
{
if (h->dynindx == -1)
{
struct bfd_strtab_hash *dynstr;
h->dynindx = elf_hash_table (info)->dynsymcount;
++elf_hash_table (info)->dynsymcount;
h->dynstr_index =
(unsigned long) _bfd_stringtab_add (elf_hash_table (info)->dynstr,
h->root.root.string,
true, false);
dynstr = elf_hash_table (info)->dynstr;
if (dynstr == NULL)
{
/* Create a strtab to hold the dynamic symbol names. */
elf_hash_table (info)->dynstr = dynstr = elf_stringtab_init ();
if (dynstr == NULL)
return false;
}
h->dynstr_index = ((unsigned long)
_bfd_stringtab_add (dynstr, h->root.root.string,
true, false));
if (h->dynstr_index == (unsigned long) -1)
return false;
}
@ -3975,12 +3990,11 @@ elf_link_add_object_symbols (abfd, info)
format. FIXME: If there are no input BFD's of the same
format as the output, we can't make a shared library. */
if (info->shared
&& elf_hash_table (info)->dynobj == NULL
&& ! elf_hash_table (info)->dynamic_sections_created
&& abfd->xvec == info->hash->creator)
{
if (! elf_link_create_dynamic_sections (abfd, info))
goto error_return;
elf_hash_table (info)->dynobj = abfd;
}
}
else
@ -4065,14 +4079,11 @@ elf_link_add_object_symbols (abfd, info)
abfd->sections = NULL;
/* If this is the first dynamic object found in the link, create
the special sections required for dynamic linking. We need
to put them somewhere, and attaching them to the first
dynamic object is as good place as any. */
if (elf_hash_table (info)->dynobj == NULL)
the special sections required for dynamic linking. */
if (! elf_hash_table (info)->dynamic_sections_created)
{
if (! elf_link_create_dynamic_sections (abfd, info))
goto error_return;
elf_hash_table (info)->dynobj = abfd;
}
/* Add a DT_NEEDED entry for this dynamic object. */
@ -4464,11 +4475,11 @@ elf_link_add_object_symbols (abfd, info)
}
/* Create some sections which will be filled in with dynamic linking
information. The ABFD argument is an input file which is a dynamic
object. The dynamic sections take up virtual memory space when the
final executable is run, so we need to create them before addresses
are assigned to the output sections. We work out the actual
contents and size of these sections later. */
information. ABFD is an input file which requires dynamic sections
to be created. The dynamic sections take up virtual memory space
when the final executable is run, so we need to create them before
addresses are assigned to the output sections. We work out the
actual contents and size of these sections later. */
boolean
elf_link_create_dynamic_sections (abfd, info)
@ -4480,6 +4491,15 @@ elf_link_create_dynamic_sections (abfd, info)
struct elf_link_hash_entry *h;
struct elf_backend_data *bed;
if (elf_hash_table (info)->dynamic_sections_created)
return true;
/* Make sure that all dynamic sections use the same input BFD. */
if (elf_hash_table (info)->dynobj == NULL)
elf_hash_table (info)->dynobj = abfd;
else
abfd = elf_hash_table (info)->dynobj;
/* Note that we set the SEC_IN_MEMORY flag for all of these
sections. */
flags = SEC_ALLOC | SEC_LOAD | SEC_HAS_CONTENTS | SEC_IN_MEMORY;
@ -4500,18 +4520,18 @@ elf_link_create_dynamic_sections (abfd, info)
|| ! bfd_set_section_alignment (abfd, s, LOG_FILE_ALIGN))
return false;
/* The first .dynsym symbol is a dummy. */
elf_hash_table (info)->dynsymcount = 1;
s = bfd_make_section (abfd, ".dynstr");
if (s == NULL
|| ! bfd_set_section_flags (abfd, s, flags | SEC_READONLY))
return false;
/* Create a strtab to hold the dynamic symbol names. */
elf_hash_table (info)->dynstr = elf_stringtab_init ();
if (elf_hash_table (info)->dynstr == NULL)
return false;
{
elf_hash_table (info)->dynstr = elf_stringtab_init ();
if (elf_hash_table (info)->dynstr == NULL)
return false;
}
s = bfd_make_section (abfd, ".dynamic");
if (s == NULL
@ -4550,7 +4570,12 @@ elf_link_create_dynamic_sections (abfd, info)
backend set the right flags. The backend will normally create
the .got and .plt sections. */
bed = get_elf_backend_data (abfd);
return (*bed->elf_backend_create_dynamic_sections) (abfd, info);
if (! (*bed->elf_backend_create_dynamic_sections) (abfd, info))
return false;
elf_hash_table (info)->dynamic_sections_created = true;
return true;
}
/* Add an entry to the .dynamic table. */
@ -4777,7 +4802,6 @@ NAME(bfd_elf,size_dynamic_sections) (output_bfd, soname, rpath, info,
asection **sinterpptr;
{
bfd *dynobj;
size_t dynsymcount;
asection *s;
Elf_Internal_Sym isym;
size_t i;
@ -4787,127 +4811,138 @@ NAME(bfd_elf,size_dynamic_sections) (output_bfd, soname, rpath, info,
*sinterpptr = NULL;
dynobj = elf_hash_table (info)->dynobj;
dynsymcount = elf_hash_table (info)->dynsymcount;
/* If there were no dynamic objects in the link, there is nothing to
do here. */
if (dynobj == NULL)
return true;
*sinterpptr = bfd_get_section_by_name (dynobj, ".interp");
BFD_ASSERT (*sinterpptr != NULL || info->shared);
/* Set the size of the .dynsym and .hash sections. We counted the
number of dynamic symbols in elf_link_add_object_symbols. We
will build the contents of .dynsym and .hash when we build the
final symbol table, because until then we do not know the correct
value to give the symbols. We built the .dynstr section as we
went along in elf_link_add_object_symbols. */
s = bfd_get_section_by_name (dynobj, ".dynsym");
BFD_ASSERT (s != NULL);
s->_raw_size = dynsymcount * sizeof (Elf_External_Sym);
s->contents = (bfd_byte *) bfd_alloc (output_bfd, s->_raw_size);
if (s->contents == NULL && s->_raw_size != 0)
if (elf_hash_table (info)->dynamic_sections_created)
{
bfd_set_error (bfd_error_no_memory);
return false;
}
size_t dynsymcount;
bfd_size_type strsize;
/* The first entry in .dynsym is a dummy symbol. */
isym.st_value = 0;
isym.st_size = 0;
isym.st_name = 0;
isym.st_info = 0;
isym.st_other = 0;
isym.st_shndx = 0;
elf_swap_symbol_out (output_bfd, &isym,
(Elf_External_Sym *) s->contents);
*sinterpptr = bfd_get_section_by_name (dynobj, ".interp");
BFD_ASSERT (*sinterpptr != NULL || info->shared);
for (i = 0; elf_buckets[i] != 0; i++)
{
bucketcount = elf_buckets[i];
if (dynsymcount < elf_buckets[i + 1])
break;
}
/* Set the size of the .dynsym and .hash sections. We counted
the number of dynamic symbols in elf_link_add_object_symbols.
We will build the contents of .dynsym and .hash when we build
the final symbol table, because until then we do not know the
correct value to give the symbols. We built the .dynstr
section as we went along in elf_link_add_object_symbols. */
dynsymcount = elf_hash_table (info)->dynsymcount;
s = bfd_get_section_by_name (dynobj, ".dynsym");
BFD_ASSERT (s != NULL);
s->_raw_size = dynsymcount * sizeof (Elf_External_Sym);
s->contents = (bfd_byte *) bfd_alloc (output_bfd, s->_raw_size);
if (s->contents == NULL && s->_raw_size != 0)
{
bfd_set_error (bfd_error_no_memory);
return false;
}
s = bfd_get_section_by_name (dynobj, ".hash");
BFD_ASSERT (s != NULL);
s->_raw_size = (2 + bucketcount + dynsymcount) * (ARCH_SIZE / 8);
s->contents = (bfd_byte *) bfd_alloc (output_bfd, s->_raw_size);
if (s->contents == NULL)
{
bfd_set_error (bfd_error_no_memory);
return false;
}
memset (s->contents, 0, s->_raw_size);
/* The first entry in .dynsym is a dummy symbol. */
isym.st_value = 0;
isym.st_size = 0;
isym.st_name = 0;
isym.st_info = 0;
isym.st_other = 0;
isym.st_shndx = 0;
elf_swap_symbol_out (output_bfd, &isym,
(Elf_External_Sym *) s->contents);
put_word (output_bfd, bucketcount, s->contents);
put_word (output_bfd, dynsymcount, s->contents + (ARCH_SIZE / 8));
for (i = 0; elf_buckets[i] != 0; i++)
{
bucketcount = elf_buckets[i];
if (dynsymcount < elf_buckets[i + 1])
break;
}
elf_hash_table (info)->bucketcount = bucketcount;
s = bfd_get_section_by_name (dynobj, ".hash");
BFD_ASSERT (s != NULL);
s->_raw_size = (2 + bucketcount + dynsymcount) * (ARCH_SIZE / 8);
s->contents = (bfd_byte *) bfd_alloc (output_bfd, s->_raw_size);
if (s->contents == NULL)
{
bfd_set_error (bfd_error_no_memory);
return false;
}
memset (s->contents, 0, s->_raw_size);
if (soname != NULL)
{
bfd_size_type indx;
put_word (output_bfd, bucketcount, s->contents);
put_word (output_bfd, dynsymcount, s->contents + (ARCH_SIZE / 8));
indx = _bfd_stringtab_add (elf_hash_table (info)->dynstr, soname,
true, true);
if (indx == (bfd_size_type) -1
|| ! elf_add_dynamic_entry (info, DT_SONAME, indx))
return false;
}
elf_hash_table (info)->bucketcount = bucketcount;
if (rpath != NULL)
{
bfd_size_type indx;
if (soname != NULL)
{
bfd_size_type indx;
indx = _bfd_stringtab_add (elf_hash_table (info)->dynstr, rpath,
true, true);
if (indx == (bfd_size_type) -1
|| ! elf_add_dynamic_entry (info, DT_RPATH, indx))
indx = _bfd_stringtab_add (elf_hash_table (info)->dynstr, soname,
true, true);
if (indx == (bfd_size_type) -1
|| ! elf_add_dynamic_entry (info, DT_SONAME, indx))
return false;
}
if (rpath != NULL)
{
bfd_size_type indx;
indx = _bfd_stringtab_add (elf_hash_table (info)->dynstr, rpath,
true, true);
if (indx == (bfd_size_type) -1
|| ! elf_add_dynamic_entry (info, DT_RPATH, indx))
return false;
}
s = bfd_get_section_by_name (dynobj, ".dynstr");
BFD_ASSERT (s != NULL);
s->_raw_size = _bfd_stringtab_size (elf_hash_table (info)->dynstr);
/* Find all symbols which were defined in a dynamic object and make
the backend pick a reasonable value for them. */
elf_link_hash_traverse (elf_hash_table (info),
elf_adjust_dynamic_symbol,
(PTR) info);
/* Add some entries to the .dynamic section. We fill in some of the
values later, in elf_bfd_final_link, but we must add the entries
now so that we know the final size of the .dynamic section. */
if (bfd_get_section_by_name (output_bfd, ".init") != NULL)
{
if (! elf_add_dynamic_entry (info, DT_INIT, 0))
return false;
}
if (bfd_get_section_by_name (output_bfd, ".fini") != NULL)
{
if (! elf_add_dynamic_entry (info, DT_FINI, 0))
return false;
}
strsize = _bfd_stringtab_size (elf_hash_table (info)->dynstr);
if (! elf_add_dynamic_entry (info, DT_HASH, 0)
|| ! elf_add_dynamic_entry (info, DT_STRTAB, 0)
|| ! elf_add_dynamic_entry (info, DT_SYMTAB, 0)
|| ! elf_add_dynamic_entry (info, DT_STRSZ, strsize)
|| ! elf_add_dynamic_entry (info, DT_SYMENT,
sizeof (Elf_External_Sym)))
return false;
}
s = bfd_get_section_by_name (dynobj, ".dynstr");
BFD_ASSERT (s != NULL);
s->_raw_size = _bfd_stringtab_size (elf_hash_table (info)->dynstr);
/* Find all symbols which were defined in a dynamic object and make
the backend pick a reasonable value for them. */
elf_link_hash_traverse (elf_hash_table (info),
elf_adjust_dynamic_symbol,
(PTR) info);
/* Add some entries to the .dynamic section. We fill in some of the
values later, in elf_bfd_final_link, but we must add the entries
now so that we know the final size of the .dynamic section. */
if (bfd_get_section_by_name (output_bfd, ".init") != NULL)
{
if (! elf_add_dynamic_entry (info, DT_INIT, 0))
return false;
}
if (bfd_get_section_by_name (output_bfd, ".fini") != NULL)
{
if (! elf_add_dynamic_entry (info, DT_FINI, 0))
return false;
}
if (! elf_add_dynamic_entry (info, DT_HASH, 0)
|| ! elf_add_dynamic_entry (info, DT_STRTAB, 0)
|| ! elf_add_dynamic_entry (info, DT_SYMTAB, 0)
|| ! elf_add_dynamic_entry (info, DT_STRSZ,
_bfd_stringtab_size (elf_hash_table (info)
->dynstr))
|| ! elf_add_dynamic_entry (info, DT_SYMENT,
sizeof (Elf_External_Sym)))
return false;
/* The backend must work out the sizes of all the other dynamic
sections. */
bed = get_elf_backend_data (output_bfd);
if (! (*bed->elf_backend_size_dynamic_sections) (output_bfd, info))
return false;
return elf_add_dynamic_entry (info, DT_NULL, 0);
if (elf_hash_table (info)->dynamic_sections_created)
{
if (! elf_add_dynamic_entry (info, DT_NULL, 0))
return false;
}
return true;
}
/* Make the backend pick a good value for a dynamic symbol. This is
@ -4923,13 +4958,15 @@ elf_adjust_dynamic_symbol (h, data)
bfd *dynobj;
struct elf_backend_data *bed;
/* If this symbol is not defined by a dynamic object, or is not
referenced by a regular object, ignore it. FIXME: Do we need to
worry about symbols which are defined by one dynamic object and
referenced by another one? */
if ((h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) != 0
|| (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_DYNAMIC) == 0
|| (h->elf_link_hash_flags & ELF_LINK_HASH_REF_REGULAR) == 0)
/* If this symbol does not require a PLT entry, and it is not
defined by a dynamic object, or is not referenced by a regular
object, ignore it. FIXME: Do we need to worry about symbols
which are defined by one dynamic object and referenced by another
one? */
if ((h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_PLT) == 0
&& ((h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) != 0
|| (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_DYNAMIC) == 0
|| (h->elf_link_hash_flags & ELF_LINK_HASH_REF_REGULAR) == 0))
return true;
/* If we've already adjusted this symbol, don't do it again. This
@ -5069,6 +5106,7 @@ elf_bfd_final_link (abfd, info)
bfd *abfd;
struct bfd_link_info *info;
{
boolean dynamic;
bfd *dynobj;
struct elf_final_link_info finfo;
register asection *o;
@ -5088,6 +5126,7 @@ elf_bfd_final_link (abfd, info)
if (info->shared)
abfd->flags |= DYNAMIC;
dynamic = elf_hash_table (info)->dynamic_sections_created;
dynobj = elf_hash_table (info)->dynobj;
finfo.info = info;
@ -5095,7 +5134,7 @@ elf_bfd_final_link (abfd, info)
finfo.symstrtab = elf_stringtab_init ();
if (finfo.symstrtab == NULL)
return false;
if (dynobj == NULL)
if (! dynamic)
{
finfo.dynsym_sec = NULL;
finfo.hash_sec = NULL;
@ -5415,7 +5454,7 @@ elf_bfd_final_link (abfd, info)
/* The sh_info field records the index of the first non local
symbol. */
symtab_hdr->sh_info = abfd->symcount;
if (dynobj != NULL)
if (dynamic)
elf_section_data (finfo.dynsym_sec->output_section)->this_hdr.sh_info = 1;
/* We get the global symbols from the hash table. */
@ -5500,9 +5539,9 @@ elf_bfd_final_link (abfd, info)
o->reloc_count = 0;
}
/* If we are linking against a dynamic object, finish up the dynamic
linking information. */
if (dynobj != NULL)
/* If we are linking against a dynamic object, or generating a
shared library, finish up the dynamic linking information. */
if (dynamic)
{
Elf_External_Dyn *dyncon, *dynconend;
@ -5577,13 +5616,18 @@ elf_bfd_final_link (abfd, info)
break;
}
}
}
/* If we have created any dynamic sections, then output them. */
if (dynobj != NULL)
{
if (! (*bed->elf_backend_finish_dynamic_sections) (abfd, info))
goto error_return;
for (o = dynobj->sections; o != NULL; o = o->next)
{
if ((o->flags & SEC_HAS_CONTENTS) == 0)
if ((o->flags & SEC_HAS_CONTENTS) == 0
|| o->_raw_size == 0)
continue;
if ((o->flags & SEC_IN_MEMORY) == 0)
{
@ -5859,7 +5903,8 @@ elf_link_output_extsym (h, data)
/* If this symbol should be put in the .dynsym section, then put it
there now. We have already know the symbol index. We also fill
in the entry in the .hash section. */
if (h->dynindx != -1)
if (h->dynindx != -1
&& elf_hash_table (finfo->info)->dynamic_sections_created)
{
struct elf_backend_data *bed;
size_t bucketcount;
@ -5885,7 +5930,8 @@ elf_link_output_extsym (h, data)
+ h->dynindx));
bucketcount = elf_hash_table (finfo->info)->bucketcount;
bucket = bfd_elf_hash ((const unsigned char *) h->root.root.string) % bucketcount;
bucket = (bfd_elf_hash ((const unsigned char *) h->root.root.string)
% bucketcount);
bucketpos = ((bfd_byte *) finfo->hash_sec->contents
+ (bucket + 2) * (ARCH_SIZE / 8));
chain = get_word (finfo->output_bfd, bucketpos);