... and const. There's no reason to have the compiler copy anonymous
objects onto the stack. And there's also no reason to allow the arrays
to be modifiable.
It isn't needed anywhere except plugin.c. The typedef can disappear.
Also make a forward declaraion for ld_plugin_input_file in plugin.h
so that this header can be used without first including plugin-api.h.
bfd/
* plugin.h (struct ld_plugin_input_file): Forward declare.
(struct plugin_data_struct): Move to..
* plugin.c: ..here.
(add_symbols): Size plugin_data without using type.
* archive.c: Don't include plugin-api.h.
* elflink.c: Likewise.
* format.c: Likewise.
binutils/
* ar.c: Don't include plugin-api.h or ansidecl.h. Only
include plugin.h when BFD_SUPPORTS_PLUGINS.
* nm.c: Don't include plugin-api.h. Only include plugin.h
when BFD_SUPPORTS_PLUGINS.
* objcopy.c: Likewise.
ld/
* ldfile.c: Don't include plugin-api.h.
* ldmain.c: Likewise.
So far, SFrame sections were of type SHT_PROGBITS.
As per ELF specification, SHT_PROGBITS indicates that the section holds
information defined by the program, whose format and meaning are
determined solely by the program.
On the linker side, SHT_PROGBITS should be reserved for the simple "cat
contents after applying relocs" semantics.
Currently, the only way to know that a section contains SFrame stack
trace data is if consumer checks for section name. Such a check for
section name is not quite conformant to ELF principles.
Some of this was discussed here
https://sourceware.org/pipermail/binutils/2025-March/140181.html
With this change, the SFrame sections generated by gas, ld will have
section type set to SHT_GNU_SFRAME. The new section type is defined in
the SHT_LOOS/SHT_HIOS space. The SFrame parsing routine
_bfd_elf_parse_sframe () now admits sections only when the the section
type is SHT_GNU_SFRAME.
No special handling / validation is done at the moment for the case of
manual creation of SFrame sections via obj_elf_section (). Add function
level comments for now to add a note about this.
Although the default handling for (sh_type >= SHT_LOOS && sh_type <=
SHT_HIOS) is sufficient when SHT_GNU_SFRAME is in that range, it makes
sense to add it as a case of its own.
bfd/
* elf-sframe.c (_bfd_elf_parse_sframe): Check if section type is
SHT_GNU_SFRAME.
(_bfd_elf_set_section_sframe): Set SHT_GNU_SFRAME for output
SFrame section.
* elflink.c (obj_elf_section): Use section type for check
instead of section name.
* elfxx-x86.c: Set SHT_GNU_SFRAME for SFrame sections for
.plt* sections.
* elf.c (bfd_section_from_shdr): Add case for SHT_GNU_SFRAME.
binutils/
* readelf.c (get_os_specific_section_type_name): Add
SHT_GNU_SFRAME.
gas/
* NEWS: Announce emitted SFrame sections have SHT_GNU_SFRAME
set.
* config/obj-elf.c (obj_elf_attach_to_group): Add comments to
indicate no special handling for SFrame yet.
* dw2gencfi.c (cfi_finish): Set SHT_GNU_SFRAME for emitted
SFrame section.
ld/
* NEWS: Announce emitted SFrame sections have SHT_GNU_SFRAME
set.
gas/testsuite/
* gas/cfi-sframe/cfi-sframe.exp: Add new test.
* gas/cfi-sframe/cfi-sframe-common-1b.d: New test.
* gas/cfi-sframe/cfi-sframe-common-1b.s: New test.
include/
* elf/common.h (SHT_GNU_SFRAME): Add new section type for SFrame
stack trace information.
libsframe/doc/
* sframe-spec.texi: Add expected ELF section type.
commit 2707d55e53
Author: Michael Matz <matz@suse.de>
Date: Mon Mar 31 15:57:08 2025 +0200
skipped the LTO archive member even when the earlier item is also an
archive. Instead, skip the LTO archive member only if the earlier item
is a shared library.
bfd/
PR ld/32846
PR ld/32854
* elflink.c (elf_link_add_archive_symbols): Skip the LTO archive
member only if the earlier item is a shared library.
ld/
PR ld/32846
PR ld/32854
* testsuite/ld-plugin/lto.exp: Run ld/32846 test.
* testsuite/ld-plugin/pr32846a.c: New file.
* testsuite/ld-plugin/pr32846b.c: Likewise.
* testsuite/ld-plugin/pr32846c.c: Likewise.
* testsuite/ld-plugin/pr32846d.c: Likewise.
* testsuite/ld-plugin/pr32846e.c: Likewise.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
when a shared library defines 'foo@@FOO' (default version),
a static archive defines 'foo', the shared lib comes in front
of the archive and under effect of --as-needed, and the requesting
object file uses LTO, then the link editor was wrongly including
the definition from the static archive. It must use the one
from the shared lib, like in the non-LTO or the --no-as-needed case.
See the added testcase that would wrongly print "FAIL" before
this patch.
The problem stems from several connected problems:
(1) only the decorated symbol was entered into first_hash (the hash
table designed to handle definition order in the pre-LTO-plugin
phase of the symbol table walks)
(2) in the archive symbol walk only the undecorated name would be
looked up in first_hash (and hence not found due to (1))
(3) in the archive symbol walk first_hash would only be consulted
when the linker hash table had a defined symbol. In pre-LTO
phase shared lib symbols aren't entered into the linker symbol
table.
So: add also the undecorated name into first_hash when it stems from
a default version and consult first_hash in the archive walker also
for currently undefined symbols. If it has an entry which doesn't
point to the archive, then it comes from an earlier library (shared or
static), and so _this_ archive won't provide the definition.
- add obj_build_attributes to struct elf_backend_data similarly sframe.
- new function _bfd_elf_write_section_build_attributes encapsulating the
writing of the build attributes section into a function.
Some of these aren't relevant to the relro bug. Some are. They all
matter if early estimation of section layout needs to be good.
PR ld/32690
* elf32-bfin.c (bfin_adjust_dynamic_symbol),
* elf32-hppa.c (elf32_hppa_late_size_sections),
* elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol),
* elf32-nds32.c (nds32_elf_adjust_dynamic_symbol),
* elf64-ppc.c (size_global_entry_stubs),
* elflink.c (_bfd_elf_tls_setup),
* elfxx-mips.c (mips_elf_add_la25_intro),
(mips_elf_add_la25_trampoline),
(_bfd_mips_elf_adjust_dynamic_symbol),
* elfxx-x86.c (_bfd_x86_elf_late_size_sections): Use
bfd_link_align_section to ensure correct output section
alignment.
Commit 8d97c1a53f claimed to replace all einfo calls using %F with
a call to fatal. It did so only for the ld/ directory. This patch
adds a "fatal" to linker callbacks, and replaces those calls in bfd/
too.
This introduces a new function which should be used whenever the
linker needs to increase section alignment after mapping input to
output sections.
PR ld/32690
* linker.c (bfd_link_align_section): New function.
* elflink.c (_bfd_elf_adjust_dynamic_copy): Use it.
* bfd-in2.h: Regenerate.
Since at the function entry, there is
flags = bed->dynamic_sec_flags;
we can replace bed->dynamic_sec_flags with flags.
* elflink.c (_bfd_elf_create_got_section): Replace
bed->dynamic_sec_flags with flags.
(_bfd_elf_link_create_dynamic_sections): Likewise.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
u.compact.extries wasn't being freed anywhere. Free it when
destroying the linker hash table. Also free u.dwarf.aray there in
case errors result in the linker not getting to the slightly earlier
free in write_dwarf_eh_frame_hdr.
* elf-eh-frame.c (write_dwarf_eh_frame_hdr): Don't exit without
freeing u.dwarf.array.
* elflink.c (_bfd_elf_link_hash_table_free): Free u.compact.entries
and u.dwarf.array.
This arranges to free section relocs cached in elf_section_data. To
do that, some relocs stored there need to use bfd_malloc buffers
rather than bfd_alloc ones.
* elf.c (_bfd_elf_free_cached_info): Free relocs.
* elf32-ppc.c (ppc_elf_relax_section): Realloc relocs rather
than malloc, copy, free old.
* elf64-ppc.c (get_relocs): bfd_malloc relocs.
* elflink.c (_bfd_elf_link_info_read_relocs): Always
bfd_malloc relocs.
This modifies _bfd_elf_free_cached_info to unmap/free section
contents. To do that we need to *not* free sections where contents
are bfd_alloc'd or point to constant strings or somesuch. I've chosen
to implement this be adding another flag to struct bfd_section,
"alloced" to say the section contents can't be freed. Most of the
patch is about setting that flag in many places.
symtab_hdr.contents looks to be malloc'd memory, except in one case.
Change that one case to also be malloc'd and free when we are done.
* elf.c (swap_out_syms): bfd_malloc outbound_syms.
(_bfd_elf_free_cached_info): Free symtab_hdr.contents.
* elflink.c (init_reloc_cookie): Correct cache_size. locsyms
is an array of Elf_Internal_Sym.
Many targets leaked parts of the elf_link_hash_table. Fix that by
making _bfd_elf_link_hash_table_init set up hash_table_free correctly,
so that targets that extend elf_link_hash_table without adding
anything that needs freeing, will use _bfd_elf_link_hash_table_free.
* elflink.c (elf_link_add_object_symbols): Always free
nondeflt_vers. Don't return false without freeing.
(_bfd_elf_link_hash_table_init): Set hash_table_free here..
(_bfd_elf_link_hash_table_create): ..rather than here.
(elf_link_swap_symbols_out): Don't free strtab here..
(elf_link_add_object_symbols): ..do so here instead. Don't
omit freeing on some error return paths.
The set_loc array attached to eh-frame sec_info isn't freed, and is
used in _bfd_elf_eh_frame_section_offset. Rather than finding a
suitable late stage of linking past any b_e_e_f_s_o use, I decided
this might as well persist until the bfd is closed.
Some memory is freed in _bfd_elf_discard_section_eh_frame_hdr, but
the function isn't always called, so fix that too.
* elf-eh-frame.c (_bfd_elf_parse_eh_frame): bfd_alloc the
set_loc array.
(find_merged_cie): Use bfd_malloc rather than malloc.
(_bfd_elf_discard_section_eh_frame_hdr): Move condition under
which this function does anything except free memory from..
* elflink.c (bfd_elf_discard_info): ..here.
Change the mmap support added with commit 9ba56acee5 to always mmap
memory with PROT_READ | PROT_WRITE. Prior to that commit most file
contents were read into a buffer allocated with bfd_alloc or
bfd_malloc and thus the memory was read/write. Even after that commit
any section contents with relocations must be read/write to apply the
relocs. Making them all read/write is not a major change, and it
should not introduce any measurable linker slowdown for contents that
are not modified. More importantly, it removes a BFD behaviour
difference that only triggers when large files are involved.
PR 32266
PR 32109
* libbfd.c (bfd_mmap_local): Remove prot param. Always mmap
with PROT_READ | PROT_WRITE. Adjust all calls.
(_bfd_mmap_temporary): Rename from _bfd_mmap_readonly_temporary.
(_bfd_munmap_temporary): Rename from _bfd_munmap_readonly_temporary.
_bfd_mmap_persistent): Rename from _bfd_mmap_readonly_persistent.
(_bfd_generic_get_section_contents): Use PROT_READ | PROT_WRITE
regardless of relocs.
* libbfd-in.h: Update decls to suit. Make non-USE_MMAP variants
static inline functions.
* elflink.c: Update all uses of _bfd_mmap functions.
* elf.c: Likewise.
(bfd_elf_get_str_section): Revert commit 656f8fbaae.
* libbfd.h: Regenerate.
While for executables properly aligning sections within the file can be
quite relevant, the same is of pretty little importance for relocatable
object files. Avoid passing "true" into
_bfd_elf_assign_file_position_for_section() when dealing with object
files, but compensate minimally by applying log_file_align in such
cases as a cap to the alignment put in place.
Commit 68bbe11833 results in a lot of follow up work, much of which
likely is still to be done. (And yes, since this is all for corrupted
or fuzzed object files, a whole lot of work doesn't much benefit
anyone. It was a bad idea to put NULL in asymbol->name.) So I'm
changing the approach to instead put a unique empty string for symbols
with a corrupted st_name. An empty string won't require much work to
ensure nm, objcopy, objdump etc. won't crash, since these tools
already must work with unnamed local symbols.
The unique empty string is called bfd_symbol_error_name. This patch
uses that name string for corrupted symbols in the ELF and COFF
backends. Such symbols are displayed by nm and objdump as the
translated string "<corrupt>", which is what the COFF backend used to
put directly into corrupted symbols.
ie. it's the way I should have written the original patch, plus a few
tides and cleanups I retained from the reverted patches.
Plus some tidies to swap_out_syms.
* elf.c (swap_out_syms): Handle NULL sym name. Use correct type
for return of _bfd_elf_strtab_add. Simplify.
* elflink.c (bfd_elf_match_symbols_in_sections): Handle NULL
sym name.
When plugin_object_p is called by elf_link_is_defined_archive_symbol to
check if a symbol in archive is a real definition, set archive member
plugin_format to bfd_plugin_yes_unused to avoid including the unused LTO
archive members in linker output. When plugin_object_p is called as
known used, call plugin claim_file if plugin_format is bfd_plugin_unknown
or bfd_plugin_yes_unused.
To get the proper support for archives with LTO common symbols with GCC,
the GCC fix for
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116361
is needed.
bfd/
PR ld/32083
* archures.c (bfd_arch_get_compatible): Treat bfd_plugin_yes_unused
the same as bfd_plugin_yes.
* elflink.c (elf_link_is_defined_archive_symbol): Likewise.
* bfd.c (bfd_plugin_format): Add bfd_plugin_yes_unused.
* plugin.c (try_claim): Try claim_file_v2 first.
* bfd-in2.h: Regenerated.
ld/
PR ld/32083
* plugin.c (plugin_call_claim_file): Add an argument to return
if LDPT_REGISTER_CLAIM_FILE_HOOK_V2 is used.
(plugin_object_p): When KNOWN_USED is false, we call plugin
claim_file if plugin_format is bfd_plugin_unknown and set
plugin_format to bfd_plugin_yes_unused on LTO object. When
KNOWN_USED is true, we call plugin claim_file if plugin_format
is bfd_plugin_unknown or bfd_plugin_yes_unused.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Never set non_ir_ref_regular for debug reference since references in
debug sections shouldn't impact LTO output.
* elflink.c (elf_link_add_object_symbols): Don't check strip for
references in debug sections when setting non_ir_ref_regular.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
The direct fix for this segfault is to test for a non-NULL bed in
_bfd_elf_link_keep_memory, but also there isn't much point in running
code for LTO if the output is binary.
PR 32067
* elflink.c (_bfd_elf_link_keep_memory): Test for non-NULL bed.
(elf_link_add_object_symbols): Don't run the loop setting
non_ir_ref_regular if the output hash table is not ELF.
There is no need to add a needed glibc version if the glibc base version
includes the needed glibc version.
PR ld/31966
* elflink.c (elf_link_add_glibc_verneed): Add glibc_minor_base.
Skip if the glibc base version includes the needed glibc version.
(_bfd_elf_link_add_glibc_version_dependency): Initialize
glibc_minor_base to INT_MAX and pass it to
elf_link_add_glibc_verneed.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
R_LARCH_ALIGN (psABI v2.30) requires a symbol index. The symbol is only
created at the first time to handle alignment directive. This means that
all other sections may use this symbol. If the section of this symbol is
discarded, there may be problems. Search it in its own section.
Remove elf_backend_data.is_rela_normal() function added at commit daeda14191.
Co-authored-by: Jinyang He <hejinyang@loongson.cn>
Reported-by: WANG Xuerui <git@xen0n.name>
Link: https://lore.kernel.org/loongarch/2abbb633-a10e-71cc-a5e1-4d9e39074066@loongson.cn/T/#t
Linker will resolve an undefined symbol only if it is referenced by
relocation. Unreferenced weak undefined symbols serve no purpose.
Weak undefined symbols appear in the dynamic symbol table only when they
are referenced by dynamic relocation. Mark symbols with relocation and
strip undefined weak symbols if they don't have relocation and aren't
in the dynamic symbol table.
bfd/
PR ld/31652
* elf-bfd.h (elf_link_hash_entry): Add has_reloc.
* elf-vxworks.c (elf_vxworks_emit_relocs): Set has_reloc.
* elflink.c (_bfd_elf_link_output_relocs): Likewise.
(elf_link_output_extsym): Strip undefined weak symbols if they
don't have relocation and aren't in the dynamic symbol table.
ld/
PR ld/31652
* testsuite/ld-elf/elf.exp: Run undefweak tests.
* testsuite/ld-elf/undefweak-1.rd: New file.
* testsuite/ld-elf/undefweak-1a.s: Likewise.
* testsuite/ld-elf/undefweak-1b.s: Likewise.
* testsuite/ld-x86-64/weakundef-1.nd: Likewise.
* testsuite/ld-x86-64/weakundef-1a.s: Likewise.
* testsuite/ld-x86-64/weakundef-1b.s: Likewise.
* testsuite/ld-x86-64/x86-64.exp: Run undefweak tests.
Also skip the archive if the symbol isn't referenced by a regular object.
bfd/
PR ld/31644
* elflink.c (elf_link_add_archive_symbols): Also skip the archive
if the symbol isn't referenced by a regular object.
ld/
PR ld/31644
* testsuite/ld-plugin/lto.exp: Run PR ld/31644 tests.
* testsuite/ld-plugin/pr31644a.c: New test.
* testsuite/ld-plugin/pr31644b.c: Likewise.
* testsuite/ld-plugin/pr31644c.c: Likewise.
Normally, the section contents is allocated by bfd_alloc which is freed
when the object is closed. But the .dynamic section contents is allocated
by bfd_realloc, which should be freed by calling free. Add a dynamic
field to elf_link_hash_table for the .dynamic section and free its
contents in _bfd_elf_link_hash_table_free.
* elf-bfd.h (elf_link_hash_table): Add dynamic.
* elflink.c (_bfd_elf_link_create_dynamic_sections): Set the
dynamic field in elf_link_hash_table.
(_bfd_elf_add_dynamic_entry): Use hash_table->dynamic.
(_bfd_elf_strip_zero_sized_dynamic_sections): Likewise.
(bfd_elf_add_dt_needed_tag): Likewise.
(elf_finalize_dynstr): Likewise.
(_bfd_elf_link_hash_table_free): Free htab->dynamic->contents.
(bfd_elf_final_link): Use htab->dynamic.
* elfxx-x86.c (_bfd_x86_elf_finish_dynamic_sections): Use
htab->elf.dynamic.
Seen running "LTO 1" under valgrind.
==1443263== Invalid read of size 1
==1443263== at 0x484CFE4: strcmp (vg_replace_strmem.c:939)
==1443263== by 0x56E16C: bfd_hash_lookup (hash.c:564)
==1443263== by 0x5A3C8F: elf_link_add_to_first_hash (elflink.c:4316)
==1443263== by 0x5AE60F: elf_link_add_object_symbols (elflink.c:5663)
==1443263== by 0x5B0672: bfd_elf_link_add_symbols (elflink.c:6333)
==1443263== by 0x41448F: load_symbols (ldlang.c:3129)
==1443263== by 0x4149D8: open_input_bfds (ldlang.c:3621)
==1443263== by 0x414968: open_input_bfds (ldlang.c:3569)
==1443263== by 0x4166A2: lang_process (ldlang.c:8162)
==1443263== by 0x4194D5: main (ldmain.c:504)
==1443263== Address 0x525e230 is 192 bytes inside a block of size 4,064 free'd
==1443263== at 0x484810F: free (vg_replace_malloc.c:974)
==1443263== by 0x8D4D87: objalloc_free_block (objalloc.c:248)
==1443263== by 0x5AEACC: elf_link_add_object_symbols (elflink.c:5790)
==1443263== by 0x5B0672: bfd_elf_link_add_symbols (elflink.c:6333)
==1443263== by 0x41448F: load_symbols (ldlang.c:3129)
==1443263== by 0x4149D8: open_input_bfds (ldlang.c:3621)
==1443263== by 0x414968: open_input_bfds (ldlang.c:3569)
==1443263== by 0x4166A2: lang_process (ldlang.c:8162)
==1443263== by 0x4194D5: main (ldmain.c:504)
PR ld/31482
PR ld/31489
* elflink.c (elf_link_add_to_first_hash): Add "copy" param.
(elf_link_add_object_symbols): Flag that name must be copied
when appending version string to symbol name.
Add elf_link_first_hash_entry and use it for first_hash. Free first_hash
before freeing the main hash table.
PR ld/31482
PR ld/31489
* elf-bfd.h (elf_link_hash_table): Change first_hash to
bfd_hash_table.
* elflink.c (elf_link_first_hash_entry): New.
(elf_link_first_hash_newfunc): Likewise.
(elf_link_add_to_first_hash): Updated.
(elf_link_add_object_symbols): Initialize first_hash with
elf_link_first_hash_newfunc.
(elf_link_add_object_symbols): Updated.
(elf_link_add_archive_symbols): Likewise.
(_bfd_elf_link_hash_table_free): Free first_hash before freeing
the main hash table.
GCC doesn't put builtin function symbol references, which are defined in
the shared C library, in the IR symbol table. When linker rescans shared
objects and archives for newly added symbol references generated from the
IR inputs, it skips definitions of the builtin functions in shared
objects and archives.
Add first_hash to elf_link_hash_table to track unreferenced definitions
defined first in shared objects and archives. Always use them to resolve
any references.
bfd/
PR ld/31482
PR ld/31489
* elf-bfd.h (elf_link_hash_table): Add first_hash.
* elflink.c (elf_link_add_to_first_hash): New function.
(elf_link_add_object_symbols): Initialize first_hash for an IR
input. Always use the first definition in shared object. Add
the first unreferenced dynamic definition to first_hash.
(_bfd_elf_archive_symbol_lookup): Add the first unreferenced
definition to first_hash..
(elf_link_add_archive_symbols): Use the symbol definition in
archive if symbol is defined first in this archive.
(_bfd_elf_link_hash_table_free): Also free first_hash.
ld/
PR ld/31482
PR ld/31489
* testsuite/ld-plugin/lto.exp: Add PR ld/31482 and PR ld/31489
tests.
* testsuite/ld-elf/pr31482a-no-lto.c: New file.
* testsuite/ld-elf/pr31482b-no-lto.c: Likewise.
* testsuite/ld-elf/pr31482c-no-lto.c: Likewise.
* testsuite/ld-elf/pr31482d-no-lto.c: Likewise.
* testsuite/ld-plugin/pass1.out: Likewise.
* testsuite/ld-plugin/pr31482a.c: Likewise.
* testsuite/ld-plugin/pr31482b.c: Likewise.
* testsuite/ld-plugin/pr31482c.c: Likewise.
Commit c6291d749a introduced a number of errors, found by clang.
elf.c:456:7: error: variable 'alloc_ext_size' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (_bfd_mul_overflow (symcount, extsym_size, &amt))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
elf.c:464:7: error: variable 'alloc_extshndx_size' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (bfd_seek (ibfd, pos, SEEK_SET) != 0
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
elflink.c:2837:11: error: variable 'alloc1_size' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (internal_relocs == NULL)
^~~~~~~~~~~~~~~~~~~~~~~
elflink.c:12595:16: error: variable 'ext_size' set but not used [-Werror,-Wunused-but-set-variable]
size_t ext_size = 0;
* elf.c (bfd_elf_get_elf_syms): Fix use of uninitialised variables.
* elflink.c (_bfd_elf_link_info_read_relocs): Likewise.
(bfd_elf_final_link): Fix set but not used warning.
To copy input section contents, add _bfd_elf_link_mmap_section_contents
and _bfd_elf_link_munmap_section_contents to mmap in the input sections.
* elf-bfd.h (_bfd_elf_link_mmap_section_contents): New.
(_bfd_elf_link_munmap_section_contents): Likewise.
* elf.c (elf_mmap_section_contents): New.
(_bfd_elf_mmap_section_contents): Use it.
(_bfd_elf_link_mmap_section_contents): New.
(_bfd_elf_link_munmap_section_contents): Likewise.
* elflink.c (elf_link_input_bfd): Call
_bfd_elf_link_mmap_section_contents instead of
bfd_get_full_section_contents. Call
_bfd_elf_link_munmap_section_contents to munmap the section
contents.
(bfd_elf_final_link): When mmap is used, initialize
max_contents_size to _bfd_minimum_mmap_size and increase it
for compressed or linker created sections or sections whose
rawsize != size.
