The linker tries to put the end of the last section in the relro
segment exactly on a page boundary, because the relro segment itself
must end on a page boundary. If for any reason this can't be done,
padding is inserted. Since the end of the relro segment is typically
between .got and .got.plt, padding effectively increases the size of
the GOT. This isn't nice for targets and code models with limited GOT
addressing.
The problem with the current code is that it doesn't cope very well
with aligned sections in the relro segment. When making .got aligned
to a 256 byte boundary for PowerPC64, I found that often the initial
alignment attempt failed and the fallback attempt to be less than
adequate. This is a particular problem for PowerPC64 since the
distance between .got and .plt affects the size of plt call stubs,
leading to "stubs don't match calculated size" errors.
So this rewrite takes a direct approach to calculating a new relro
base. Starting from the last section in the segment, we calculate
where it must start to position its end on the boundary, or as near as
possible considering alignment requirements. The new start then
becomes the goal for the previous section to end, and so on for all
sections. This of course ignores the possibility that user scripts
will place . = ALIGN(xxx); in the relro segment, or provide section
address expressions. In those cases we might fail, but the old code
probably did too, and a fallback is provided.
ld/
* ldexp.h (struct ldexp_control): Delete dataseg.min_base. Add
data_seg.relro_offset.
* ldexp.c (fold_binary <DATA_SEGMENT_ALIGN>): Don't set min_base.
(fold_binary <DATA_SEGMENT_RELRO_END>): Do set relro_offset.
* ldlang.c (lang_size_sections): Rewrite code adjusting relro
segment base to line up last section on page boundary.
ld/testsuite/
* ld-x86-64/pr18176.d: Update.
gold marks _init and _fini via symbol, ld marks them via section
(default scripts set .init and .fini section KEEP). This makes it
possible for people to write their own _init and not bother to put the
function into the right section.
PR ld/18223
* ldlang.c (lang_process): Add _init and _fini to gc_sym_list.
Adjusting the start of the relro segment in order to make it end
exactly on a page boundary runs into difficulties when sections in the
relro segment are aligned; Adjusting the start by (next_page - end)
sometimes results in more than that adjustment occurring at the end,
overrunning the page boundary. So when that occurs we try a new lower
start position by masking the adjusted start with the maximum section
alignment. However, we didn't consider that this masked start address
may in fact be before the initial relro base, which is silly since
that can only increase padding at the relro end.
I've also moved some calculations closer to where they are used, and
comments closer to the relevant statements.
* ldlang.c (lang_size_sections): When alignment of sections
results in relro base adjustment being too large, don't go lower
than the initial value.
* ldexp.c (fold_binary <DATA_SEGMENT_RELRO_END>): Comment.
* scripttempl/elf.sc (DATA_SEGMENT_ALIGN): Omit SEGMENT_SIZE
alignment when SEGMENT_SIZE is the same as MAXPAGESIZE.
LTO output objects have an STT_FILE symbol using the name of the file,
a temporary file. This results in executables that can't be exactly
reproduced, so the file name needs to be dropped. We don't want to
lose all file symbols when linking a mix of lto and non-lto objects as
a file symbol can be used to figure which source file generated a
given local symbol. So lto output objects need to be marked.
I chose to mark lto output objects with a new bfd flag. This flag is
also used to fix a bug in the link-once handling; An object being
loaded after "loading_lto_outputs" is set might be one extracted from
an archive to satisfy new references from lto objects, not an lto
object itself.
The new flag is copied from archive to elements, and the same done
for no_export. This fixes a bug in that --exclude-libs doesn't work
with thin archives. I'm not completely happy with this part of the
patch and may revist this to avoid the hack in
_bfd_look_for_bfd_in_cache.
PR ld/17973
include/
* bfdlink.h (struct bfd_link_info): Delete loading_lto_outputs.
bfd/
* bfd.c (struct bfd): Add lto_output.
* linker.c (_bfd_handle_already_linked): Explicitly test for
objects added by the lto plugin.
* opncls.c (_bfd_new_bfd_contained_in): Copy lto_output and
no_export flags from archive.
* archive.c (open_nested_file): New function, setting lto_output
and no_export, extracted from..
(find_nested_archive): ..here. Flip params. Rename from
_bfd_find_nested_archive.
(_bfd_get_elt_at_filepos): Correct var typo. Use open_nested_file.
(_bfd_look_for_bfd_in_cache): Copy no_export.
* elflink.c (elf_link_add_object_symbols): Remove now unnecessary
my_archive->no_export test.
(elf_link_input_bfd): Drop existing lto_output STT_FILE syms.
Don't use the file name when adding lto_output STT_FILE sym.
* bfd-in2.h: Regenerate.
ld/
* ldlang.h (struct lang_input_statement_flags): Add lto_output.
* ldlang.c (lang_process): Don't set loading_lto_outputs.
* ldfile.c (ldfile_try_open_bfd): Transfer entry flags.lto_output
to bfd.
* plugin.c (add_input_file, add_input_library): Set flags.lto_output.
The changes to reorder sections for better relro protection on powerpc64,
3e2b0f31, 23283c1b, and 5ad18f16, run into a problem with xlc.
xlc -qdatalocal puts global variables into .toc, which means that .toc
must be writable. The simplest way to accomplish this is to edit the
linker script to remove .toc sections from .got on detecting xlc object
files.
bfd/
* elf64-ppc.h (struct ppc64_elf_params): Add "object_in_toc".
* elf64-ppc.c (ppc64_elf_add_symbol_hook): Assume that global symbols
in .toc indicate xlc compiled code that might require a rw .toc.
ld/
* emulparams/elf64ppc.sh (INITIAL_READWRITE_SECTIONS): Define.
* emultempl/ppc64elf.em (params): Init new field.
(ppc_after_open): New function.
(LDEMUL_AFTER_OPEN): Define.
* ldlang.c (lang_final): Whitespace fix.
ld/testsuite/
* ld-powerpc/tocvar.d, * ld-powerpc/tocvar.s: New test.
* ld-powerpc/tocnovar.d, * ld-powerpc/tocnovar.s: New test.
* ld-powerpc/powerpc.exp: Run tocvar and tocnovar.
This patch fixes PR 4643 by allowing symbols in the LENGTH and ORIGIN
fields of MEMORY regions. Previously, only constants and constant
expressions are allowed.
For the AVR target, this helps define memory constraints more
accurately (per device), without having to create a ton of device
specific linker scripts.
ld/
PR 4643
* ldexp.c (fold_name): Fold LENGTH only after
lang_first_phase_enum.
* ldgram.y (memory_spec): Don't evaluate ORIGIN and LENGTH
rightaway.
* ldlang.h (struct memory_region_struct): Add origin_exp and
length_exp fields.
* ldlang.c (lang_do_memory_regions): New.
(lang_memory_region_lookup): Initialize origin_exp and
length_exp fields.
(lang_process): Call lang_do_memory_regions.
ld/testsuite/
* ld-scripts/memory.t: Define new symbol tred.
* ld-scripts/memory_sym.t: New.
* ld-scripts/script.exp: Perform MEMORY with symbols test, and
conditionally check values of linker symbols.
When creating a linker mapfile (using -Map=MAPFILE), we previously would
always try to evaluate the expression from a PROVIDE statement.
However, this is not always safe, consider:
PROVIDE (foo = 0x10);
PROVIDE (bar = foo);
In this example, if neither 'foo' or 'bar' is needed, then while
generating the linker mapfile evaluating the expression for 'foo' is
harmless (just the value 0x10). However, evaluating the expression for
'bar' requires the symbol 'foo', which is undefined. This used to cause
a fatal error.
This patch changes the behaviour, so that when the destination of the
PROVIDE is not defined (that is the PROVIDE is not going to provide
anything) the expression is not evaluated, and instead a special string
is displayed to indicate that the linker is discarding the PROVIDE
statement.
This change not only fixes the spurious undefined symbol error, but also
means that a user can now tell if a PROVIDE statement has provided
anything by inspecting the linker mapfile, something that could not be
done before.
ld/ChangeLog:
* ldlang.c (print_assignment): Only evaluate the expression for a
PROVIDE'd assignment when the destination is being defined.
Display a special message for PROVIDE'd symbols that are not being
provided.
ld/testsuite/ChangeLog:
* ld-scripts/provide-4.d: New file.
* ld-scripts/provide-4-map.d: New file.
* ld-scripts/provide-4.t: New file.
* ld-scripts/provide-5.d: New file.
* ld-scripts/provide-5.s: New file.
* ld-scripts/provide-5-map.d: New file.
* ld-scripts/provide-5.t: New file.
* ld-scripts/provide.exp: Run the provide-4.d and provide-5.d
tests.
Running lang_common before garbage collection means slightly less work
in garbage collection code, since common symbols should no longer
appear there. It does have the side effect of keeping linker script
symbols (at least those defined outside of sections) global too,
hence some testsuite churn.
bfd/
PR 17165
* elf-bfd.h (ELF_COMMON_DEF): Note that this might be true for
linker script assignments too.
* elflink.c (elf_gc_sweep_symbol): Don't drop ELF_COMMON_DEF syms.
(bfd_elf_gc_mark_dynamic_ref_symbol): Similarly.
ld/
PR 17165
* ldlang.c (lang_process): Run lang_common before lang_gc_sections.
ld/testsuite/
* ld-gc/pr14265.d,
* ld-cris/tls-gc-68.d,
* ld-cris/tls-gc-69.d,
* ld-cris/tls-gc-70.d,
* ld-cris/tls-gc-71.d,
* ld-cris/tls-gc-75.d,
* ld-cris/tls-gc-76.d,
* ld-cris/tls-gc-79.d,
* ld-mmix/bpo-10.d,
* ld-mmix/bpo-11.d: Update.
This moves support code for DEFINED to ldexp.c where it is used,
losing the lang_ prefix on identifiers. Two new functions are needed
to initialize and clean up to hash table, but other than that there
are no functional changes here.
* ldexp.c (struct definedness_hash_entry, definedness_table)
(definedness_newfunc, symbol_defined, update_definedness): Move
and rename from..
* ldlang.h (struct lang_definedness_hash_entry): ..here,..
* ldlang.c (lang_definedness_table, lang_definedness_newfunc)
(lang_symbol_defined, lang_update_definedness): ..and here.
* ldexp.c (ldexp_init, ldexp_finish): New functions, extracted from..
* ldlang.c (lang_init, lang_finish): ..here.
* ldexp.h (ldexp_init, ldexp_finish): Declare.
* ldlang.h (lang_symbol_defined, lang_update_definedness): Delete.
* ldmain.c (main): Call ldexp_init and ldexp_finish.
* ldlang.c (lang_add_input_file): If the first character in the
filename is '=', prepend the sysroot and force the context of that
input file to non-sysroot.
The "input_flags.sysrooted = 0" thing described in the comment is
covered by the testsuite part ("root-anchored =-prefixed script
inside"), but only observable for --with-sysroot configurations.
The idea here is to drop .eh_frame FDEs corresponding to dropped
comdat group sections or linkonce sections, but not perform changes in
encoding.
bfd/
PR 17467
* elf-eh-frame.c (ENSURE_NO_RELOCS): Don't stop at first NONE reloc.
(_bfd_elf_parse_eh_frame): When relocatable output, don't set
flags enabling conversion of CIEs and FDEs to use relative encoding.
(find_merged_cie): Similarly.
(_bfd_elf_write_section_eh_frame): Don't edit FDEs when
relocatable, except for CIE pointer.
* elflink.c (bfd_elf_reloc_symbol_deleted_p): Return true for
relocs against symbols in dropped comdat group sections.
(bfd_elf_discard_info): Do some eh_frame optimisation when
relocatable.
ld/
* ldlang.c (lang_add_section): Set up map_head.s and map_tail.s when
relocatable.
Presents .eh_frame input sections to the optimisation machinery in
elf-eh-frame.c in the order they are given by the linker script.
PR 16563
bfd/
* elflink.c (bfd_elf_discard_info): Process .eh_frame and .stab
in the order they are mapped to output sections.
ld/
* ldlang.c (map_head_is_link_order): Rename from
stripped_excluded_sections.
(lang_clear_os_map): New function, extracted from..
(strip_excluded_output_sections): ..here.
* ldlang.h (lang_clear_os_map): Declare.
* ldwrite.c (ldwrite): Call lang_clear_os_map.
* emultempl/sh64elf.em (sh64_elf_${EMULATION_NAME}_after_allocation):
Likewise.
When a shared library appears within --start-group/--end-group ld may
only discover a need for loading the library on the second or
subsequent pass over archive libraries, as more objects are extracted.
ld/
PR 17068
* ldlang.c (load_symbols): Always check flags.reload.
(open_input_bfds): Always reload --as-needed shared libraries,
not just when rescanning.
* ldlang.h (struct lang_input_statement_flags): Update reload comment.
* plugin.c (plugin_should_reload): Assume shared library arg.
* plugin.h (plugin_should_reload): Update comment.
ld/testsuite
* ld-elf/pr17068.s: New.
* ld-elf/pr17068a.s: New.
* ld-elf/pr17068b.s: New.
* ld-elf/pr17068c.s: New.
* ld-elf/pr17068d.s: New.
* ld-elf/pr17068e.s: New.
* ld-elf/pr17068ez.s: New.
* ld-elf/elf.exp: Run new test.
sys/param.h on recent versions of powerpc glibc ends up including
asm/elf.h via asm/sigcontex.h. asm/elf.h defines R_PPC_* and R_PPC64_*
macros, which clash with our include/elf/ppc.h and include/elf/ppc64.h.
It turns out that no current source uses LD_PATHMAX, so there is no
need for limits.h or sys/param.h, except for one occurrence of UINT_MAX.
I don't have a quarrel with limits.h, but it seems unnecessary just
for UINT_MAX.
* sysdep.h: Don't include limits.h and sys/param.h. Don't
include unistd.h twice.
(LD_PATHMAX): Don't define.
* ldlang.c (lang_common): Don't use UINT_MAX.
1) _SDA_BASE_ and _SDA2_BASE_ and defined automatically, in a similar
manner to the way _GLOBAL_OFFSET_TABLE_ is handled. It's a little
more complicated to remove the symbols because _SDA_BASE_ needs to
be there if either .sdata or .sbss is present, and similarly for
_SDA2_BASE.
2) The linker created .sdata and .sdata2 sections used for
R_PPC_EMB_SDAI16 and R_PPC_EMB_SDA2I16 pointers are created early.
Nowadays we strip unneeded sections from the output, so it isn't
necessary to delay creating the sections.
3) The output section for targets of various SDA relocs is now checked
as per the ABI(s). We previously allowed .sdata.foo and similar,
most likely because at some stage we were checking input sections.
Also, the patch fixes a long-standing bug in size_input_sections
that affects the values of symbols defined in stripped input
sections.
PR 16952
bfd/
* elf32-ppc.c (ppc_elf_create_linker_section): Move earlier.
Remove redundant setting of htab->elf.dynobj. Don't align.
Define .sdata symbols using _bfd_elf_define_linkage_sym.
(ppc_elf_create_glink): Call ppc_elf_create_linker_section.
(create_sdata_sym): Delete.
(elf_allocate_pointer_linker_section): Rename from
elf_create_pointer_linker_section. Align section.
(ppc_elf_check_relocs): Don't call ppc_elf_creat_linker_section
directly here, or create_sdata_sym. Set ref_regular on _SDA_BASE_
and _SDA2_BASE_.
(ppc_elf_size_dynamic_sections): Remove ATTRIBUTE_UNUSED on param.
Remove unnecessary tests on _SDA_BASE_ sym.
(maybe_strip_sdasym, ppc_elf_maybe_strip_sdata_syms): New functions.
(ppc_elf_relocate_section): Tighten SDA reloc symbol section checks.
* elf32-ppc.h (ppc_elf_set_sdata_syms): Delete.
(ppc_elf_maybe_strip_sdata_syms): Declare.
ld/
* emulparams/elf32ppccommon.sh (_SDA_BASE_, _SDA2_BASE_): Delete.
* emultempl/ppc32elf.em (ppc_before_allocation): Call
ppc_elf_maybe_strip_sdata_syms.
* ldlang.c (size_input_section): Correct output_offset value
for excluded input sections.
ld:
* ldlang.c (lang_finish): Don't call bfd_link_hash_table_free here.
(output_bfd_hash_table_free_fn): New variable.
(open_output): Save the _bfd_link_hash_table_free function for the
output_bfd into output_bfd_hash_table_free_fn.
* ldmain.c (ld_cleanup): If set, call output_bfd_hash_table_free_fn
on link_info.hash.
* ldlang.h (output_bfd_hash_table_free_fn): Declare.
ld/testsuite:
* ld-mmix/wrap1.d, ld-mmix/wrap1a.s, ld-mmix/wrap1b.s,
ld-mmix/wrap1c.s, ld-mmix/wrap2.d, ld-mmix/wrap3.d,
ld-mmix/wrap3a.s, ld-mmix/wrap3b.s, ld-mmix/wrap4.d: New
tests.
When aligning input sections, we are supposed to take the fill pattern
from a FILL statement, if there is one in the output section statement.
ld/
* ldlang.c (lang_size_sections_1 <lang_input_section_enum>): Use
current "fill", not "output_section_statement->fill".
ld/testsuite/
* ld-scripts/fill.d, * ld-scripts/fill.t, * ld-scripts/fill_0.s,
* ld-scripts/fill_1.s, * ld-scripts/fill_2.s: New test.
* ld-scripts/data.exp: Run it.
For libraries without a soname, -l:libfoo.so set DT_NEEDED to the search
dir plus filename, while gold and -lfoo just use the filename. This
patch fixes the inconsistency.
* ldlang.h (full_name_provided): New input flag.
* ldlang.c (new_afile): Don't use lang_input_file_is_search_file_enum
for -l:namespec. Instead use lang_input_file_is_l_enum with
full_name_provided flag.
* ldlfile.c (ldfile_open_file_search): Don't complete lib name if
full_name_provided flag is set.
* emultempl/elf32.em (gld${EMULATION_NAME}_open_dynamic_archive):
Handle full_name_provided libraries. Tidy EXTRA_SHLIB_EXTENSION
support. Set DT_NEEDED for -l:namespec as namespec.
* emultempl/aix.em (ppc_after_open_output): Handle full_name_provided.
* emultempl/linux.em (gld${EMULATION_NAME}_open_dynamic_archive):
Don't handle full_name_provided libraries.
* emultempl/pe.em (gld${EMULATION_NAME}_open_dynamic_archive): Ditto.
* emultempl/pep.em (gld${EMULATION_NAME}_open_dynamic_archive): Ditto.
* emultempl/vms.em (gld${EMULATION_NAME}_open_dynamic_archive): Ditto.
Ensures TLS orphans are placed adjacent to existing TLS sections,
and fixes places where the output_section_statement flags (which might
not be set) were tested when bfd_section flags were available.
* ldlang.c (lang_output_section_find_by_flags): Be careful to
test look->bfd_section->flags if available rather than
look->flags. Separate SEC_THREAD_LOCAL handling from
SEC_READONLY loop, and rewrite.
Adds a section for --as-needed libraries to a linker map file, similar
to what we do for archive libraries.
bfd/
* elflink.c (elf_link_add_object_symbols): Call minfo for --as-needed.
ld/
* ldlang.c (asneeded_list_head, asneeded_list_tail): New vars.
(lang_init): Initialise them.
(lang_print_asneeded): New function.
(lang_process): Call lang_print_asneeded.
* ldlang.h (struct asneeded_minfo): New.
(asneeded_list_tail): Declare.
* ldmain.c (add_archive_element): Improve archive map heading.
* ldmisc.c (minfo): Stash --as-needed info.
Modifies ld machinery tracking linker script assignments to notice all
assignments, not just those symbols mentioned in DEFINED().
ld/
PR ld/14962
* ldlang.h (struct lang_definedness_hash_entry): Add by_object and
by_script. Make iteration a single bit field.
(lang_track_definedness, lang_symbol_definition_iteration): Delete.
(lang_symbol_defined): Declare.
* ldlang.c (lang_statement_iteration): Expand comment a little.
(lang_init <lang_definedness_table>): Make it bigger.
(lang_track_definedness, lang_symbol_definition): Delete.
(lang_definedness_newfunc): Update.
(lang_symbol_defined): New function.
(lang_update_definedness): Create entries here. Do track whether
script definition of symbol is valid, even when also defined in
an object file.
* ldexp.c (fold_name <DEFINED>): Update.
(fold_name <NAME>): Allow self-assignment for absolute symbols
defined in a linker script.
ld/testsuite/
* ld-scripts/pr14962-2.d,
* ld-scripts/pr14962-2.t: New test.
* ld-scripts/expr.exp: Run it.
Tie output section statements to their associated output section via
output section userdata. This allows us to avoid hash lookups which
are slower and fail when multiple output sections have the same name.
* ldlang.h (lang_output_section_get): Define.
* ldlang.c (lang_output_section_get): Likewise.
(init_os): Set the output_section userdata to the output
section statement.
* emultempl/hppaelf.em: Use lang_output_section_get instead of
lang_output_section_find where applicable.
* emultempl/aarch64elf.em: Likewise.
* emultempl/aix.em: Likewise.
* emultempl/armelf.em: Likewise.
* emultempl/m68hc1xelf.em: Likewise.
* emultempl/metagelf.em: Likewise.
* emultempl/mipself.em: Likewise.
* emultempl/ppc64elf.em: Likewise.
* emultempl/spuelf.em: Likewise.
A long time ago ld made use of userdata to tie an output section to
its lang_input_statement_struct object file. Some time later Joern
made map file printing of symbols at lot faster, using userdata on
input sections. That complicated allocation of userdata, and when the
output section use disappeared a year later, the code wasn't properly
cleaned up. This patch does that cleanup, and also tidies the symbol
printing code to not allocate userdata where it won't be needed. We
don't print symbols defined in the absolute section or in output
sections.
* ld.h (fat_section_userdata_type, get_userdata): Move to..
* ldlang.h (input_section_userdata_type, get_userdata): ..here.
* ldlang.c (init_map_userdata): Delete. Fold into..
(sort_def_symbol): ..here. Don't attach input section userdata
to output sections or global bfd sections.
(lang_map): Don't pre-allocate input section userdata.
(init_os): Don't allocate userdata for output sections.
(print_all_symbols): Update.
This patch fixes 2 GNU_RELRO segment bugs:
1. lang_size_sections didn't properly align base to the maximum
alignment power of sections between DATA_SEGMENT_ALIGN and
DATA_SEGMENT_RELRO_END.
2. ld failed to adjust LOAD segment to generate GNU_RELRO segment
when LOAD segment doesn't fit GNU_RELRO segment. This is
https://sourceware.org/bugzilla/show_bug.cgi?id=14207
We "fixed" ld by not generating GNU_RELRO segment. This patch
adjusts LOAD segment to generate GNU_RELRO segment. It fixes
PR ld/16322 and at the same time it also fixes PR binutils/16323
since now we can adjust LOAD segment if it is too small.
bfd/
PR ld/14207
PR ld/16322
PR binutils/16323
* elf.c (_bfd_elf_map_sections_to_segments): Don't check section
size for PT_GNU_RELRO segment.
(assign_file_positions_for_load_sections): If PT_LOAD segment
doesn't fit PT_GNU_RELRO segment, adjust its p_filesz and p_memsz.
ld/
PR ld/14207
PR ld/16322
PR binutils/16323
* ldlang.c (lang_size_sections): Properly align RELRO base.
ld/testsuite/
PR ld/14207
PR ld/16322
PR binutils/16323
* ld-elf/pr16322.d: New file.
* ld-elf/pr16322.s: Likewise.
* ld-x86-64/pr14207.d: Expect PT_GNU_RELRO segment.
ld/
* ldlang.c (lang_size_sections_1): When given an lma_region align
LMA as per VMA only if lma_region is the same as region.
ld/testsuite/
* ld-scripts/rgn-at6.s, * ld-scripts/rgn-at6.t, * ld-scripts/rgn-at6.d,
* ld-scripts/rgn-at7.t, * ld-scripts/rgn-at7.d: New tests.
* ldexp.h (struct ldexp_control): Add "assign_name".
* ldexp.c (fold_name <NAME>): Compare and clear assign_name on match.
(exp_fold_tree_1): Remove existing code testing for self assignment.
Instead set and test expld.assign_name.
* ldlang.c (scan_for_self_assignment): Delete.
(print_assignment): Instead set and test expld.assign_name.
* ld.h (ld_config_type): New flag member separate_code.
* emultempl/elf32.em
(gld${EMULATION_NAME}_before_parse): Set it based on $SEPARATE_CODE.
* ldlang.c (ldlang_override_segment_assignment): If it's set, then
always return TRUE when SEC_CODE differs between the sections.
