The GNU coding standard says error messages should be of the form
program:sourcefile:lineno: message
or
program: message
and
"The string message should not begin with a capital letter when it
follows a program name and/or file name, because that isn’t the
beginning of a sentence. (The sentence conceptually starts at the
beginning of the line.) Also, it should not end with a period."
This patch does that for ppc, and removes some British spelling.
I've also switched some error output from using the linker callback
einfo to _bfd_error_handler, due to improved compilation time
argument checking now done for the latter function.
bfd/
* elf32-ppc.c: Standardize error/warning messages. Use
_bfd_error_handler rather than einfo when einfo features not used.
* elf64-ppc.c: Likewise.
ld/
* testsuite/ld-powerpc/attr-gnu-12-21.d: Update.
* testsuite/ld-powerpc/attr-gnu-4-12.d: Update.
* testsuite/ld-powerpc/attr-gnu-4-13.d: Update.
* testsuite/ld-powerpc/attr-gnu-4-21.d: Update.
* testsuite/ld-powerpc/attr-gnu-4-23.d: Update.
* testsuite/ld-powerpc/attr-gnu-4-31.d: Update.
* testsuite/ld-powerpc/attr-gnu-4-32.d: Update.
* testsuite/ld-powerpc/attr-gnu-8-23.d: Update.
This reverts most of commit 1be5d8d3bb.
Left in place are addition of --no-plt-align to some ppc32 ld tests
and the ld.texinfo --no-plt-thread-safe fix.
This fixes a "bug" in that nops emitted as part of code optimization
were being relocated. As it happens the relocation value was always
zero so the nop wasn't changed. Whew! I've also moved the use of
"howto" later since I was caught out in some recent code changes with
the howto not matching r_type.
* elf64-ppc.c (ppc64_elf_relocate_section): Don't relocate nops
emitted for toc sequence optimization. Set and use "howto" later.
bfdI would like to fix instances of the following warning, when building
with clang with no special CFLAGS other than -g3 -O0.
/home/emaisin/src/binutils-gdb/bfd/elflink.c:5425:45: error: performing pointer arithmetic on a null pointer has undefined behavior [-Werror,-Wnull-pointer-arithmetic]
return (struct elf_link_hash_entry *) 0 - 1;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^
Replacing those with "(struct elf_link_hash_entry *) -1" gets rid of the
warning. I wanted to check that it didn't change the resulting code, so
I tried to build this:
$ cat test.c
int *before()
{
return (int *) 0 - 1;
}
int *after()
{
return (int *) - 1;
}
$ gcc -c test.c -g
$ objdump -d test.o
test.o: file format elf64-x86-64
Disassembly of section .text:
0000000000000000 <before>:
0: 55 push %rbp
1: 48 89 e5 mov %rsp,%rbp
4: 48 c7 c0 fc ff ff ff mov $0xfffffffffffffffc,%rax
b: 5d pop %rbp
c: c3 retq
000000000000000d <after>:
d: 55 push %rbp
e: 48 89 e5 mov %rsp,%rbp
11: 48 c7 c0 ff ff ff ff mov $0xffffffffffffffff,%rax
18: 5d pop %rbp
19: c3 retq
This shows that the previous code doesn't actually return -1 as the
function documentation says, but the new one does, so it's kind of a
bugfix.
bfd * elf64-ppc.c (ppc64_elf_archive_symbol_lookup): Avoid pointer
arithmetic on NULL pointer.
* elflink.c (_bfd_elf_archive_symbol_lookup,
elf_link_add_archive_symbols): Likewise.
ld * ldexp.c (fold_name, exp_fold_tree_1): Avoid pointer arithmetic
on NULL pointer.
https://bugzilla.redhat.com/show_bug.cgi?id=1523457
I haven't analyzed this myself, I'm relying on Nick's excellent
analysis. What I believe is happening is that after some number of
stub sizing iterations, a long-branch stub needs to be converted to a
plt-branch, but either due to stub alignment or other stubs shrinking
in size, the stub group section size doesn't change.
That means we exit from ppc64_elf_size_stubs after sizing with an
incorrect layout, in fact the additional .branch_lt entry overlays
.got! Since .TOC. is normally set to .got + 0x8000 the stub sizing
code decides that entry is within +/-32k of the TOC pointer and so a
three insn stub is sufficient. When we come to build the stubs using
a correct non-overlaying layout, a four insn plt-branch stub is
generated and the stub group size doesn't match that calculated
earlier.
* elf64-ppc.c (ppc64_elf_size_stubs): Iterate sizing when
.branch_lt changes size.
Asking for ppc32 plt call stubs to be aligned at 32 byte boundaries
didn't quite work. For ld.bfd they were spaced 32 bytes apart, but
only started on a 16 byte boundary. ld.gold also didn't get it right.
Finding that bug made me check over the ppc64 plt stub alignment,
where I found that negative values for alignment (meaning align to
minimize boundary crossing) were not accepted. Since no one has
complained about that, I guess I could have removed the feature from
ld.bfd documentation, but I've opted instead to correct the code.
I've also added an optional alignment paramenter for ppc32
--plt-align, for some consistency with gold and ppc64 ld.bfd.
bfd/
* elf32-ppc.c (ppc_elf_create_glink): Correct alignment of .glink.
* elf64-ppc.c (ppc64_elf_size_stubs): Handle negative plt_stub_align.
(ppc64_elf_build_stubs): Likewise.
gold/
* powerpc.cc (param_plt_align): New function supplying default
--plt-align values. Use it..
(Stub_table::plt_call_align): ..here, and..
(Output_data_glink::global_entry_align): ..here.
(Stub_table::stub_align): Correct 32-bit minimum alignment.
ld/
* emultempl/ppc32elf.em: Support optional --plt-align arg.
* emultempl/ppc64elf.em: Support negative --plt-align arg.
This is in preparation for the next patch adding Spectre variant 2
mitigation for PowerPC and PowerPC64. Besides tidying code involved
in stub output (to reduce the number of places where bctr is output),
the patch adds some user visible features:
1) PowerPC64 ELFv2 global entry stubs now are aligned under the
control of --plt-align, with a default alignment of 32 bytes.
2) PowerPC64 __glink_PLTresolve is no longer padded out with nops.
3) PowerPC32 PLT stubs are aligned under the control of --plt-align,
with the default alignment being 16 bytes as before.
4) The PowerPC32 branch/nop table emitted before __glink_PLTresolve
is now smaller in many cases. It was sized incorrectly when the
__tls_get_addr_opt stub was used, and unnecessarily included space
for local ifuncs.
bfd/
* elf32-ppc.c (GLINK_ENTRY_SIZE): Add parameters, handle
__tls_get_addr_opt, and alignment sizing.
(TLS_GET_ADDR_GLINK_SIZE): Delete.
(is_nonpic_glink_stub): Don't use GLINK_ENTRY_SIZE.
(ppc_elf_get_synthetic_symtab): Recognize stubs spaced at 4, 6,
or 8 insns.
(ppc_elf_link_hash_table_create): Init new ppc_elf_params field.
(allocate_dynrelocs): Use new GLINK_ENTRY_SIZE.
(ppc_elf_size_dynamic_sections): Likewise. Size branch table
by PLT reloc count.
(write_glink_stub): Handle __tls_get_addr_opt stub.
Pad out to size given by GLINK_ENTRY_SIZE.
(ppc_elf_relocate_section): Adjust write_glink_stub call.
(ppc_elf_finish_dynamic_symbol): Likewise.
(ppc_elf_finish_dynamic_sections): Write PLTresolve without using
insn array since so many need rewriting.
* elf32-ppc.h (struct ppc_elf_params): Add plt_stub_align.
* elf64-ppc.c (GLINK_PLTRESOLVE_SIZE): Rename from
GLINK_CALL_STUB_SIZE. Add htab param and evaluate to size without
nops. Adjust all uses.
(ppc64_elf_get_synthetic_symtab): Don't use GLINK_CALL_STUB_SIZE
in glink_vma calculation.
(struct ppc_link_hash_table): Add global_entry section pointer.
(create_linkage_sections): Create separate section for global
entry stubs.
(PPC_LO, PPC_HI, PPC_HA): Move earlier.
(size_global_entry_stubs): Handle sizing for aligned stubs.
(ppc64_elf_size_dynamic_sections): Handle global_entry alloc,
and don't stash end of glink branch table in rawsize.
(ppc_build_one_stub): Rewrite stub size calculations.
(build_global_entry_stubs): Use new section.
(ppc64_elf_build_stubs): Don't pad __glink_PLTresolve with nops.
Build lazy link stubs out to end of section. Build global entry
stubs in new section.
gold/
* options.h (plt_align): Support for PowerPC32 too.
* powerpc.cc (Stub_table::stub_align): Heed --plt-align for 32-bit.
(Stub_table::plt_call_size, branch_stub_size): Tidy.
(Stub_table::plt_call_align): Implement using stub_align.
(Output_data_glink::global_entry_align): New function.
(Output_data_glink::global_entry_off): New function.
(Output_data_glink::global_entry_address): Use global_entry_off.
(Output_data_glink::pltresolve_size): New function, replacing
pltresolve_size_ constant. Update all uses.
(Output_data_glink::add_global_entry): Align offset.
(Output_data_glink::set_final_data_size): Use global_entry_align.
(Stub_table::do_write): Don't pad __glink_PLTrelsolve with nops.
Tidy stub output. Use global_entry_off.
ld/
* emultempl/ppc32elf.em (params): Init new field.
(enum ppc32_opt): New enum to define OPTION_* values. Add
OPTION_PLT_ALIGN and OPTION_NO_PLT_ALIGN.
(PARSE_AND_LIST_LONGOPTS): Handle new options.
(PARSE_AND_LIST_ARGS_CASES): Likewise.
(PARSE_AND_LIST_OPTIONS): Likewise. Break up help output.
* emultempl/ppc64elf.em (ppc_add_stub_section): Init alignment
correctly for negative --plt-stub-align.
* testsuite/ld-powerpc/elfv2exe.d,
* testsuite/ld-powerpc/elfv2so.d,
* testsuite/ld-powerpc/relbrlt.d,
* testsuite/ld-powerpc/relbrlt.s,
* testsuite/ld-powerpc/tlsexe.d,
* testsuite/ld-powerpc/tlsexe.r,
* testsuite/ld-powerpc/tlsexe32.d,
* testsuite/ld-powerpc/tlsexe32.g,
* testsuite/ld-powerpc/tlsexe32.r,
* testsuite/ld-powerpc/tlsexetoc.d,
* testsuite/ld-powerpc/tlsexetoc.r,
* testsuite/ld-powerpc/tlsopt5_32.d,
* testsuite/ld-powerpc/tlsso.d,
* testsuite/ld-powerpc/tlstocso.d: Update for changed stub order.
PowerPC64 has its own mark_dynamic_ref, which needs the same change as
made by d664fd41e1 to the generic ELF version. Some other targets
discard more than just .data, so allow for that too in expected ld
messages.
bfd/
PR ld/22649
* elf64-ppc.c (ppc64_elf_gc_mark_dynamic_ref): Ignore dynamic
references on forced local symbols.
ld/
PR ld/22649
* testsuite/ld-elf/pr22649.msg: Allow other messages.
* testsuite/ld-elf/shared.exp: Check that --gc-sections is
supported before running ld/22649 tests.
Past tense is wrong for a comment before some action.
* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Comment tidy.
* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Likewise.
* elfnn-aarch64.c (elfNN_aarch64_adjust_dynamic_symbol): Likewise.
In early October, HJ Lu added support for a number of targets to "Dump
dynamic relocation in read-only section with minfo". This extends
that support to more targets, displays the symbol involved, and splits
the existing function that sets TEXTREL into a "readonly_dynrelocs"
and "maybe_set_textrel" function. I'll need "readonly_dynrelocs" if I
ever get around to fixing "pr22374 function pointer initialization"
fails.
am33_2.0, arc, bfin, hppa64, mn10300, and nios2 fail to mark a binary
needing text relocations with DT_TEXTREL. That's not good. xtensa also
fails to do so but complains about "dangerous relocation: dynamic
relocation in read-only section" so I reckon that is fine and have
marked the test as an xfail. The other targets need maintainer
attention.
Curiously, the map file dump wasn't added for x86, so the map test
currently fail on x86. It also fails on alpha, am33_2.0, arc, bfin,
hppa64, ia64, m68k, mips, mn10300, nios2, score and vax. cris
complains with "tmpdir/textrel.o, section .rodata: relocation
R_CRIS_32 should not be used in a shared object; recompile with -fPIC"
so I've marked it as an xfail.
bfd/
* elf32-hppa.c (maybe_set_textrel): Print symbol for map file output.
* elf32-ppc.c (maybe_set_textrel): Likewise.
* elf64-ppc.c (maybe_set_textrel): Likewise.
* elf32-arm.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing..
(elf32_arm_readonly_dynrelocs): ..this.
* elf32-lm32.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elf32-m32r.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elf32-metag.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elf32-nds32.c: Delete unnecessary forward declarations.
(readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elf32-or1k.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elf32-s390.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elf32-sh.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elf32-tic6x.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing..
(elf32_tic6x_readonly_dynrelocs): ..this.
* elf32-tilepro.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elf64-s390.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elfnn-aarch64.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing..
(aarch64_readonly_readonly_dynrelocs): ..this.
* elfnn-riscv.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elfxx-sparc.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
* elfxx-tilegx.c (readonly_dynrelocs): New function.
(maybe_set_textrel): New function, replacing old version of..
(readonly_dynrelocs): ..this.
ld/
* testsuite/ld-elf/shared.exp: Run new textrel tests.
* testsuite/ld-elf/textrel.map: New file.
* testsuite/ld-elf/textrel.rd: New file.
* testsuite/ld-elf/textrel.s: New file.
* testsuite/ld-elf/textrel.warn: New file.
This cleans up yet more craziness with non_got_ref.
PR 22533
* elf32-hppa.c (elf32_hppa_copy_indirect_symbol): Don't do anything
special with non_got_ref for weak aliases.
(elf32_hppa_check_relocs): Tweak setting of non_got_ref.
(elf32_hppa_adjust_dynamic_symbol): When initialising weak aliases,
don't uselessly copy non_got_ref. Clear dyn_relocs instead if
strong symbol is allocated in dynbss. Tidy comments.
(elf32_hppa_relocate_section): Comment fix.
* elf32-ppc.c (ppc_elf_copy_indirect_symbol): Don't do anything
special with non_got_ref for weak aliases.
(ppc_elf_adjust_dynamic_symbol): When initialising weak aliases,
don't uselessly copy non_got_ref. Clear dyn_relocs instead if
strong symbol is allocated in dynbss. Tidy comments.
* elf64-ppc.c (ppc64_elf_copy_indirect_symbol): Don't do anything
special with non_got_ref for weak aliases.
(ppc64_elf_adjust_dynamic_symbol): When initialising weak aliases,
don't uselessly copy non_got_ref. Clear dyn_relocs instead if
strong symbol is allocated in dynbss. Tidy comments.
Now that u.alias is circular, weakref just duplicates its function.
Also, function symbols shouldn't be on the alias list so there is no
need to use alias_readonly_dynrelocs with them.
* elf64-ppc.c (struct ppc_link_hash_entry): Delete weakref field.
(ppc64_elf_copy_indirect_symbol): Don't set weakref.
(alias_readonly_dynrelocs): Use u.alias rather than weakref.
(ppc64_elf_adjust_dynamic_symbol): Don't use
alias_readonly_dynrelocs for function symbols.
This makes the elf_link_hash_entry weakdef field, currently used to
point from a weak symbol to a strong alias, a circular list so that
all aliases can be found from any of them. A new flag, is_weakalias,
distinguishes the weak symbol from a strong alias, and is used in all
places where we currently test u.weakdef != NULL.
With the original u.weakdef handling it was possible to have two or
more weak symbols pointing via u.weakdef to a strong definition.
Obviously that situation can't map to a circular list; One or more of
the weak symbols must point at another weak alias rather than the
strong definition. To handle that, I've added an accessor function to
return the strong definition.
* elf-bfd.h (struct elf_link_hash_entry): Add is_weakalias.
Rename u.weakdef to u.alias and update comment.
(weakdef): New static inline function.
* elflink.c (bfd_elf_record_link_assignment) Test is_weakalias
rather than u.weakdef != NULL, and use weakdef function.
(_bfd_elf_adjust_dynamic_symbol): Likewise.
(_bfd_elf_fix_symbol_flags): Likewise. Clear is_weakalias on
all aliases if def has been overridden in a regular object, not
u.weakdef.
(elf_link_add_object_symbols): Delete new_weakdef flag. Test
is_weakalias and use weakdef. Set is_weakalias and circular
u.alias. Update comments.
(_bfd_elf_gc_mark_rsec): Test is_weakalias rather than
u.weakdef != NULL and use weakdef function.
* elf-m10300.c (_bfd_mn10300_elf_adjust_dynamic_symbol): Test
is_weakalias rather than u.weakdef != NULL and use weakdef
function. Assert that def is strong defined.
* elf32-arc.c (elf_arc_adjust_dynamic_symbol): Likewise.
* elf32-arm.c (elf32_arm_adjust_dynamic_symbol): Likewise.
* elf32-bfin.c (elf32_bfinfdpic_adjust_dynamic_symbol): Likewise.
(bfin_adjust_dynamic_symbol): Likewise.
* elf32-cr16.c (_bfd_cr16_elf_adjust_dynamic_symbol): Likewise.
* elf32-cris.c (elf_cris_adjust_dynamic_symbol): Likewise.
* elf32-frv.c (elf32_frvfdpic_adjust_dynamic_symbol): Likewise.
* elf32-hppa.c (elf32_hppa_adjust_dynamic_symbol): Likewise.
* elf32-i370.c (i370_elf_adjust_dynamic_symbol): Likewise.
* elf32-lm32.c (lm32_elf_adjust_dynamic_symbol): Likewise.
* elf32-m32r.c (m32r_elf_adjust_dynamic_symbol): Likewise.
* elf32-m68k.c (elf_m68k_adjust_dynamic_symbol): Likewise.
* elf32-metag.c (elf_metag_adjust_dynamic_symbol): Likewise.
* elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol): Likewise.
* elf32-nds32.c (nds32_elf_adjust_dynamic_symbol): Likewise.
* elf32-nios2.c (nios2_elf32_adjust_dynamic_symbol): Likewise.
* elf32-or1k.c (or1k_elf_adjust_dynamic_symbol): Likewise.
* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Likewise.
* elf32-s390.c (elf_s390_adjust_dynamic_symbol): Likewise.
* elf32-score.c (s3_bfd_score_elf_adjust_dynamic_symbol): Likewise.
* elf32-score7.c (s7_bfd_score_elf_adjust_dynamic_symbol): Likewise.
* elf32-sh.c (sh_elf_adjust_dynamic_symbol): Likewise.
* elf32-tic6x.c (elf32_tic6x_adjust_dynamic_symbol): Likewise.
* elf32-tilepro.c (tilepro_elf_gc_mark_hook): Likewise.
(tilepro_elf_adjust_dynamic_symbol): Likewise.
* elf32-vax.c (elf_vax_adjust_dynamic_symbol): Likewise.
* elf32-xtensa.c (elf_xtensa_adjust_dynamic_symbol): Likewise.
* elf64-alpha.c (elf64_alpha_adjust_dynamic_symbol): Likewise.
* elf64-hppa.c (elf64_hppa_adjust_dynamic_symbol): Likewise.
* elf64-ia64-vms.c (elf64_ia64_adjust_dynamic_symbol): Likewise.
* elf64-ppc.c (ppc64_elf_gc_mark_hook): Likewise.
(ppc64_elf_adjust_dynamic_symbol): Likewise.
* elf64-s390.c (elf_s390_adjust_dynamic_symbol): Likewise.
* elf64-sh64.c (sh64_elf64_adjust_dynamic_symbol): Likewise.
* elfnn-aarch64.c (elfNN_aarch64_adjust_dynamic_symbol): Likewise.
* elfnn-ia64.c (elfNN_ia64_adjust_dynamic_symbol): Likewise.
* elfnn-riscv.c (riscv_elf_adjust_dynamic_symbol): Likewise.
* elfxx-mips.c (_bfd_mips_elf_adjust_dynamic_symbol): Likewise.
* elfxx-sparc.c (_bfd_sparc_elf_gc_mark_hook): Likewise.
(_bfd_sparc_elf_adjust_dynamic_symbol): Likewise.
* elfxx-tilegx.c (tilegx_elf_gc_mark_hook): Likewise.
(tilegx_elf_adjust_dynamic_symbol): Likewise.
* elfxx-x86.c (_bfd_x86_elf_adjust_dynamic_symbol): Likewise.
The fix for the PR is to not use input_section->output_section->owner
to get to the output bfd, but use the output bfd directly since it is
available nowadays in struct bfd_link_info.
I thought it worth warning when non-empty dynamic sections are
discarded too, which meant a tweak to one of the ld tests to avoid the
warning.
bfd/
PR 22431
* elf64-ppc.c (ppc64_elf_size_dynamic_sections): Warn on discarding
non-empty dynamic section.
(ppc_build_one_stub): Take elf_gp from output bfd, not output
section owner.
(ppc_size_one_stub, ppc64_elf_next_toc_section): Likewise.
ld/
* testsuite/ld-elf/note-3.t: Don't discard .got.
There is code in bfd/elf-eh-frame.c and ld/emultempl/elf32.em that
checks for the presence of eh_frame info by testing for a section
named .eh_frame sized more than 8 bytes. The size test is to exclude
a zero terminator. A similar check in elf64-ppc.c wrongly just tested
for non-zero size before creating the linker generated .eh_frame
describing plt call and other linkage stubs. The intention was to not
generate that info unless there was some user .eh_frame. (No user
.eh_frame implies the user doesn't care about exception handling.)
Because the test in elf64-ppc.c was wrong, ld generated the stub
.eh_frame just on finding a zero .eh_frame terminator in crtend.o, but
didn't generate the corresponding .eh_frame_hdr.
* elf64-ppc.c (ppc64_elf_size_stubs): Correct test for user
.eh_frame info.
This patch was aimed at a FIXME in elf32-hppa.c, the ludicrous and
confusing fact that non_got_ref after adjust_dynamic_relocs in that
backend means precisely the inverse of what it means before
adjust_dynamic_relocs. Before, when non_got_ref is set it means there
are dynamic relocs, after, if non_got_ref is clear it means "keep
dynamic relocs" and later, "has dynamic relocs". There is a reason
why it was done that way.. Some symbols that may have dynamic
relocations pre-allocated in check_relocs turn out to not be dynamic,
and then are not seen by the backend adjust_dynamic_symbols. We want
those symbols to lose their dynamic relocs when non-pic, so it's handy
that non_got_ref means the opposite after adjust_dynamic_relocs. But
it's really confusing.
Most other targets, like ppc32, don't always set non_got_ref on
non-GOT references that have dynamic relocations. This is because the
primary purpose of non_got_ref before adjust_dynamic_relocs is to flag
symbols that might need to be copied to .dynbss, and there are
relocation types that may require dyn_relocs but clearly cannot have
symbols copied into .dynbss, for example, TLS relocations.
Why do we need a flag after adjust_dynamic_relocs to say "keep
dynamic relocations"? Well, you can discard most unwanted dyn_relocs
in the backend adjust_dynamic_relocs, and for those symbols that
aren't seen by the backend adjust_dynamic_relocs, in
allocate_dynrelocs based on a flag set by adjust_dynamic relocs,
dynamic_adjusted. That doesn't solve all our difficulties though.
relocate_section needs to know whether a symbol has dyn_relocs, and
many targets transfer dyn_relocs to a weakdef if the symbol has one.
The transfer means relocate_section can't test dyn_relocs itself and
the weakdef field has been overwritten by that time. So non_got_ref
is used to flag "this symbol has dynamic relocations" for
relocate_section.
Confused still? Well, let's hope the comments I've added help clarify
things.. The patch also fixes a case where we might wrongly emit
dynamic relocations in an executable for common and undefined symbols.
* elf32-hppa.c (elf32_hppa_adjust_dynamic_symbol): Set non_got_ref
to keep dyn_relocs, clear to discard. Comment.
(allocate_dynrelocs): Always clear non_got_ref when clearing
dyn_relocs in non-pic case. Invert non_got_ref test. Also test
dynamic_adjusted and ELF_COMMON_DEF_P. Move code deleting
dyn_relocs on undefined syms to handle for non-pic too.
(elf32_hppa_relocate_section): Simplify test for non-pic dyn relocs.
* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Set non_got_ref
to keep dyn_relocs, clear to discard. Comment.
(allocate_dynrelocs): Always clear non_got_ref when clearing
dyn_relocs in non-pic case. Invert non_got_ref test. Also test
dynamic_adjusted and ELF_COMMON_DEF_P. Move code deleting
dyn_relocs on undefined syms to handle for non-pic too.
(ppc_elf_relocate_section): Simplify test for non-pic dyn relocs.
* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Discard
dyn_relocs here. Don't bother setting non_got_ref. Comment.
(allocate_dynrelocs): Delete special handling of non-pic ELFv2
ifuncs. Move code deleting dyn_relocs on undefined symbols to
handle for non-pic too. Don't test non_got_ref. Do test
dynamic_adjusted and ELF_COMMON_DEF_P.
This patch removes unnecessary GOT IE TLS relocations in PIEs. Useful
with --no-tls-optimize, or with an enormous TLS segment. With the
default --tls-optimize in effect IE code sequences will be edited to
LE under the same circumstances we can remove the GOT reloc.
* elf32-ppc.c (got_entries_needed, got_relocs_needed): New functions.
(allocate_dynrelocs, ppc_elf_size_dynamic_sections): Use them here.
(ppc_elf_relocate_section): Don't output a dynamic relocation
for IE GOT entries in an executable.
* elf64-ppc.c (allocate_got): Trim unnecessary TPREL relocs.
(ppc64_elf_size_dynamic_sections): Likewise.
(ppc64_elf_relocate_section): Likewise.
PowerPC64 lacked the mapfile textrel warning on finding dynamic relocs
in read-only sections. This patch adds it, and tidies the
readonly_dynrelocs interface. PowerPC doesn't need a SEC_ALLOC test
because !SEC_ALLOC sections are excluded by check_relocs so will never
have dyn_relocs.
* elf32-ppc.c (readonly_dynrelocs): Delete info param. Update all
callers. Don't bother with SEC_ALLOC test. Return section pointer.
Move minfo call to..
(maybe_set_textrel): ..here.
* elf64-ppc.c (readonly_dynrelocs): Return section pointer.
(maybe_set_textrel): Call minfo to print textrel warning to map file.
We don't need a PLT entry when function pointer initialization in a
read/write section is the only reference to a given function symbol.
This patch prevents the unnecessary PLT entry, and ensures no dynamic
relocs are emitted when UNDEFWEAK_NO_DYNAMIC_RELOC says so.
bfd/
PR 22374
* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Don't create a plt
entry when just a dynamic reloc can serve. Ensure no dynamic
relocations when UNDEFWEAK_NO_DYNAMIC_RELOC by setting non_got_ref.
Expand and move the non_got_ref comment.
* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Likewise.
ld/
* testsuite/ld-powerpc/ambiguousv2.d: Remove FIXME.
polyml produces object files with the wrong OS/ABI for hppa-linux.
This, along with the fact that elf32-hppa.c is using the strictest
backend relocs_compatible, results in wrong merging of ELF symbols.
So, remove the relocs_compatible check in _bfd_elf_merge_symbol.
_bfd_elf_merge_symbol is only called nowadays from within blocks
protected by is_elf_hash_table, so "we are doing an ELF link" as the
removed comment says, is true.
Also relax relocs_compatible for hppa and powerpc. relocs_compatible
is used for more than just merging symbols, as the name suggests.
This allows objects that are in fact reasonably compatible to be
linked.
PR 22300
* elflink.c (_bfd_elf_merge_symbol): Remove relocs_compatible check.
* elf32-hppa.c (elf_backend_relocs_compatible): Define.
* elf32-ppc.c (elf_backend_relocs_compatible): Define.
* elf64-ppc.c (elf_backend_relocs_compatible): Define.
Move UNDEFWEAK_NO_DYNAMIC_RELOC to elf-bfd.h so that it can be used by
other ELF linker backends.
* elf32-ppc.c (UNDEFWEAK_NO_DYNAMIC_RELOC): Moved to ...
* elf-bfd.h (UNDEFWEAK_NO_DYNAMIC_RELOC): Here.
* elf64-ppc.c (UNDEFWEAK_NO_DYNAMIC_RELOC): Removed.
check_relocs was setting up some data used by the --gc-sections
gc_mark_hook. If we change ld to run check_relocs after gc_sections
that data needs to be set up elsewhere. Done by this patch in the
backend check_directives function (ppc64_elf_before_check_relocs).
* elf64-ppc.c (ppc64_elf_before_check_relocs): Set sec_type for
.opd whenever .opd is present and non-zero size. Move code
setting abiversion to/from output file earlier. Only set
u.opd.func_sec when --gc-sections. Read relocs and set up
u.opd.func_sec values here..
(ppc64_elf_check_relocs): ..rather than here. Simplify opd
section tests.
(ppc64_elf_edit_opd): Don't set sec_type for .opd here.
After the PR 21411 fix, the linker generated .eh_frame for ppc64 glink
can be edited by the generic code. The sequence of events goes
something like:
1) Some object file adds .eh_frame aligned to 8, making the output
.eh_frame aligned to at least 8, so linker generated .eh_frame FDE
is padded to an 8 byte boundary.
2) All .eh_frame past the glink .eh_frame is garbage collected.
3) Generic code detects that last FDE (the glink .eh_frame) doesn't
need to be padded to an 8 byte boundary, reducing size from 88 to
84.
4) elf64-ppc.c check fails.
PR 21441
* elf64-ppc.c (ppc64_elf_build_stubs): Don't check glink_eh_frame
size.
This changes the PowerPC64 --plt-align option to perform the usual
alignment of code as suggested by its name, as well as the previous
behaviour of padding so as to reduce boundary crossing. The old
behaviour is had by using a negative parameter.
The default is also changed to align plt stub code by default to 32
byte boundaries, the point being to get better bctr branch prediction
on power8 and power9 hardware.
bfd/
* elf64-ppp.c (plt_stub_pad): Handle positive and negative
plt_stub_align.
ld/
* ld.texinfo (--plt-align): Describe new behaviour of option.
* emultempl/ppc64elf.em (params): Default plt_stub_align to 5.
* testsuite/ld-powerpc/powerpc.exp: Pass --no-plt-align for
selected tests.
* testsuite/ld-powerpc/relbrlt.d: Pass --no-plt-align.
* testsuite/ld-powerpc/elfv2so.d: Adjust expected output.
In the TLS GD/LD to LE optimization, ld replaces a sequence like
addi 3,2,x@got@tlsgd R_PPC64_GOT_TLSGD16 x
bl __tls_get_addr(x@tlsgd) R_PPC64_TLSGD x
R_PPC64_REL24 __tls_get_addr
nop
with
addis 3,13,x@tprel@ha R_PPC64_TPREL16_HA x
addi 3,3,x@tprel@l R_PPC64_TPREL16_LO x
nop
When the tprel offset is small, this can be further optimized to
nop
addi 3,13,x@tprel
nop
bfd/
* elf64-ppc.c (struct ppc_link_hash_table): Add do_tls_opt.
(ppc64_elf_tls_optimize): Set it.
(ppc64_elf_relocate_section): Nop addis on TPREL16_HA, and convert
insn on TPREL16_LO and TPREL16_LO_DS relocs to use r13 when
addis would add zero.
* elf32-ppc.c (struct ppc_elf_link_hash_table): Add do_tls_opt.
(ppc_elf_tls_optimize): Set it.
(ppc_elf_relocate_section): Nop addis on TPREL16_HA, and convert
insn on TPREL16_LO relocs to use r2 when addis would add zero.
gold/
* powerpc.cc (Target_powerpc::Relocate::relocate): Nop addis on
TPREL16_HA, and convert insn on TPREL16_LO and TPREL16_LO_DS
relocs to use r2/r13 when addis would add zero.
ld/
* testsuite/ld-powerpc/tls.s: Add calls with tls markers.
* testsuite/ld-powerpc/tls32.s: Likewise.
* testsuite/ld-powerpc/powerpc.exp: Run tls marker tests.
* testsuite/ld-powerpc/tls.d: Adjust for TPREL16_HA/LO optimization.
* testsuite/ld-powerpc/tlsexe.d: Likewise.
* testsuite/ld-powerpc/tlsexetoc.d: Likewise.
* testsuite/ld-powerpc/tlsld.d: Likewise.
* testsuite/ld-powerpc/tlsmark.d: Likewise.
* testsuite/ld-powerpc/tlsopt4.d: Likewise.
* testsuite/ld-powerpc/tlstoc.d: Likewise.
There isn't a good reason for ld.bfd to behave differently from gold
in the code generated by TLS GD/LD to LE optimization.
bfd/
* elf64-ppc.c (ppc64_elf_relocate_section): When optimizing
__tls_get_addr call sequences to LE, don't move the addi down
to the nop. Replace the bl with addi and leave the nop alone.
ld/
* testsuite/ld-powerpc/tls.d: Update.
* testsuite/ld-powerpc/tlsexe.d: Update.
* testsuite/ld-powerpc/tlsexetoc.d: Update.
* testsuite/ld-powerpc/tlsld.d: Update.
* testsuite/ld-powerpc/tlsmark.d: Update.
* testsuite/ld-powerpc/tlsopt4.d: Update.
* testsuite/ld-powerpc/tlstoc.d: Update.
Tidy how these are handled in PIEs.
* elf32-ppc.c (must_be_dyn_reloc): Use bfd_link_dll. Comment.
(ppc_elf_check_relocs): Only set DF_STATIC_TLS in shared libs.
(ppc_elf_relocate_section): Comment fix.
* elf64-ppc.c (must_be_dyn_reloc): Use bfd_link_dll. Comment.
(ppc64_elf_check_relocs): Only set DF_STATIC_TLS in shared libs.
Support dynamic relocs for TPREL16 when non-pic too.
(dec_dynrel_count): Adjust TPREL16 handling as per check_relocs.
(ppc64_elf_relocate_section): Support dynamic relocs for TPREL16
when non-pic too.
..if they have dynamic relocs. An undefined symbol in a PIC object
that finds no definition ought to become dynamic in order to support
--allow-shlib-undefined, but there is nothing in the generic ELF
linker code to do this if the reference isn't via the GOT or PLT. (An
initialized function pointer is an example.) So it falls to backend
code to ensure the symbol is made dynamic.
PR 21988
* elf64-ppc.c (ensure_undef_dynamic): Rename from
ensure_undefweak_dynamic. Handle undefined too.
* elf32-ppc.c (ensure_undef_dynamic): Likewise.
* elf32-hppa.c (ensure_undef_dynamic): Likewise.
(allocate_dynrelocs): Discard undefined non-default visibility
relocs first. Make undefined syms dynamic. Tidy goto.
This makes ld warn about --plt-localentry if a version of glibc
without the necessary ld.so checks is detected, and revises the
documentation.
bfd/
* elf64-ppc.c (ppc64_elf_tls_setup): Warn on --plt-localentry
without ld.so checks.
gold/
* powerpc.cc (Target_powerpc::scan_relocs): Warn on --plt-localentry
without ld.so checks.
ld/
* ld.texinfo (plt-localentry): Revise.
The big comment in ppc64_elf_tls_setup says why. I've also added some
code to the bfd linker that catches the -lpthread -lc symbol
differences and disable generation of optimized call stubs even when
--plt-localentry is activated. Gold doesn't yet have that.
PR 21847
bfd/
* elf64-ppc.c (struct ppc_link_hash_entry): Add non_zero_localentry.
(ppc64_elf_merge_symbol): Set non_zero_localentry.
(is_elfv2_localentry0): Test non_zero_localentry.
(ppc64_elf_tls_setup): Default to --no-plt-localentry.
gold/
* powerpc.cc (Target_powerpc::scan_relocs): Default to
--no-plt-localentry.
ld/
* ld.texinfo (plt-localentry): Document.
Since the __tls_get_addr_opt stub saves LR and makes a call, eh_frame
info should be generated to describe how to unwind through the stub.
The patch also changes the way the backend iterates over stubs, from
looking at all sections in stub_bfd to which all dynamic sections are
attached as well, to iterating over the group list, which gets just
the stub sections. Most binaries will have just one or two stub
groups, so this is a little faster.
bfd/
* elf64-ppc.c (struct map_stub): Add tls_get_addr_opt_bctrl.
(stub_eh_frame_size): New function.
(ppc_size_one_stub): Set group tls_get_addr_opt_bctrl.
(group_sections): Init group tls_get_addr_opt_bctrl.
(ppc64_elf_size_stubs): Update sizing and initialization of
.eh_frame. Iteration over stubs via group list.
(ppc64_elf_build_stubs): Iterate over stubs via group list.
(ppc64_elf_finish_dynamic_sections): Update finalization of
.eh_frame.
ld/
* testsuite/ld-powerpc/tlsopt5.s: Add cfi.
* testsuite/ld-powerpc/tlsopt5.d: Update.
* testsuite/ld-powerpc/tlsopt5.wf: New file.
* testsuite/ld-powerpc/powerpc.exp: Perform new tlsopt5 test.
My PPC64_OPT_LOCALENTRY patch of June 1, git commit f378ab099d, and
the later gold change, git commit 7ee7ff7015, added an insn in
__glink_PLTresolve which needs a corresponding adjustment in the
eh_frame info for asynchronous exceptions to unwind correctly.
It would have been OK for both ABIs to use +5 for the advance before
restore of LR, since we can put the DW_CFA_restore_extended on any
insn after the actual restore and before the r12/r0 copy is clobbered,
but it's slightly better to delay as much as possible. There are
then more addresses where fewer CFA program insns are executed.
bfd/
* elf64-ppc.c (ppc64_elf_size_stubs): Correct advance to
restore of LR.
gold/
* powerpc.cc (glink_eh_frame_fde_64v2): Correct advance to
restore of LR.
(glink_eh_frame_fde_64v1): Advance to restore of LR at latest
possible insn.
My 2017-01-24 patch (commit f0158f44) wrongly applied an optimization
of GOT entries for the __tls_get_addr_opt stub, to shared libraries.
When the TLS segment layout is known, as it is for the executable and
shared libraries loaded at initial program start, powerpc supports a
__tls_get_addr optimization. On the first call to __tls_get_addr for
a given __tls_index GOT entry, the DTPMOD word is set to zero and the
DTPREL word to the thread pointer offset to the thread variable. This
allows the __tls_get_addr_opt stub to return that value immediately
without making a call into glibc for any subsequent __tls_get_addr
calls using that __tls_index GOT entry.
That's all fine, but I thought I'd be clever and when the thread
variable is local, set up the GOT entry as if __tls_get_addr had
already been called. Which is good only for the executable, since ld
cannot know the TLS layout for shared libraries.
Of course, if this only applies to executables there isn't much point
to the optimization. Normally, GD and LD code in an executable will
be converted to IE or LE, losing the __tls_get_addr call. So the only
time it will trigger is with --no-tls-optimize. Thus, revert all
support.
* elf64-ppc.c (ppc64_elf_relocate_section): Don't optimize
__tls_index GOT entries when using __tls_get_addr_opt stub.
* elf32-ppc.c (ppc_elf_relocate_section): Likewise.
These don't need a following nop. Also, a localentry:0 plt call
marked with an R_PPC64_TOCSAVE reloc should ignore the tocsave.
There's no need to save r2 in the prologue for such calls.
* elf64-ppc.c (ppc64_elf_size_stubs): Test for localentry:0 plt
calls before tocsave calls.
(ppc64_elf_relocate_section): Allow localentry:0 plt calls without
following nop.
ELFv2 functions with localentry:0 are those with a single entry point,
ie. global entry == local entry, and that have no requirement on r2 or
r12, and guarantee r2 is unchanged on return. Such an external
function can be called via the PLT without saving r2 or restoring it
on return, avoiding a common load-hit-store for small functions. The
optimization is attractive. The TOC pointer load-hit-store is a major
reason why calls to small functions that need no register saves, or
with shrink-wrap, no register saves on a fast path, are slow on
powerpc64le.
To be safe, this optimization needs ld.so support to check that the
run-time matches link-time function implementation. If a function
in a shared library with st_other localentry non-zero is called
without saving and restoring r2, r2 will be trashed on return, leading
to segfaults. For that reason the optimization does not happen for
weak functions since a weak definition is a fairly solid hint that the
function will likely be overridden. I'm also not enabling the
optimization by default unless glibc-2.26 is detected, which should
have the ld.so checks implemented.
bfd/
* elf64-ppc.c (struct ppc_link_hash_table): Add has_plt_localentry0.
(ppc64_elf_merge_symbol_attribute): Merge localentry bits from
dynamic objects.
(is_elfv2_localentry0): New function.
(ppc64_elf_tls_setup): Default params->plt_localentry0.
(plt_stub_size): Adjust size for tls_get_addr_opt stub.
(build_tls_get_addr_stub): Use a simpler stub when r2 is not saved.
(ppc64_elf_size_stubs): Leave stub_type as ppc_stub_plt_call for
optimized localentry:0 stubs.
(ppc64_elf_build_stubs): Save r2 in ELFv2 __glink_PLTresolve.
(ppc64_elf_relocate_section): Leave nop unchanged for optimized
localentry:0 stubs.
(ppc64_elf_finish_dynamic_sections): Set PPC64_OPT_LOCALENTRY in
DT_PPC64_OPT.
* elf64-ppc.h (struct ppc64_elf_params): Add plt_localentry0.
include/
* elf/ppc64.h (PPC64_OPT_LOCALENTRY): Define.
ld/
* emultempl/ppc64elf.em (params): Init plt_localentry0 field.
(enum ppc64_opt): New, replacing OPTION_* defines. Add
OPTION_PLT_LOCALENTRY, and OPTION_NO_PLT_LOCALENTRY.
(PARSE_AND_LIST_*): Support --plt-localentry and --no-plt-localentry.
* testsuite/ld-powerpc/elfv2so.d: Update.
* testsuite/ld-powerpc/powerpc.exp (TLS opt 5): Use --no-plt-localentry.
* testsuite/ld-powerpc/tlsopt5.d: Update.
Nick Clifton
Alan Modra
Simon Marchi
H.J. Lu
Yuri Chornovian