This is a linker-only solution to the incompatibility between shared
library protected visibility variables and using .dynbss and copy
relocs for non-PIC access to shared library variables.
bfd/
* elf32-ppc.c (struct ppc_elf_link_hash_entry): Add has_addr16_ha
and has_addr16_lo. Make has_sda_refs a bitfield.
(ppc_elf_check_relocs): Set new flags.
(ppc_elf_link_hash_table_create): Update default_params.
(ppc_elf_adjust_dynamic_symbol): Clear protected_def in cases
where we won't be making .dynbss entries or editing code. Set
params->pic_fixup when we'll edit code for protected var access.
(allocate_dynrelocs): Allocate got entry for edited code and
discard dyn_relocs.
(struct ppc_elf_relax_info): Add picfixup_size.
(ppc_elf_relax_section): Rename struct one_fixup to struct
one_branch_fixup. Rename fixups to branch_fixups. Size space for
pic fixups.
(ppc_elf_relocate_section): Edit non-PIC accessing protected
visibility variables to PIC. Don't emit dyn_relocs for code
we've edited.
* elf32-ppc.h (struct ppc_elf_params): Add pic_fixup.
ld/
* emultempl/ppc32elf.em: Handle --no-pic-fixup.
(params): Init new field.
(ppc_before_allocation): Enable relaxation for pic_fixup.
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.
I got the ppc476 workaround wrong. bctr (and bctrl) as the last
instruction in a page can hit the icache bug if the preceding mtctr
insn is close by, and the destination is in the first few instructions
on the next page. This scenario can occur with code generated by gcc
to implement switch statements, or in code generated to call by
function pointer.
To prevent the bctr problem it is also necessary to remove other
instructions that otherwise would be safe.
bfd/
* elf32-ppc.c (ppc_elf_relocate_section): Remove bctr from list
of safe ppc476 insns at end of page. Also remove non-branch insns.
Expand comments.
ld/
* emultempl/ppc32elf.em (no_zero_padding, ppc_finish): New functions.
(LDEMUL_FINISH): Define.
5446cbdf82 broke powerpc-lynxos,
powerpc-netware, powerpc-windiss and powerpc-vxworks.
bfd/
* elf32-ppc.c (ppc_elf_link_hash_table_create): Provide default
params for targets that don't use ppc32elf.em.
ld/
* emulparams/elf32ppcvxworks.sh: Source plt_unwind.sh and
use ppc32elf.em.
* emultempl/ppc32elf.em (ppc_after_open): Don't compile for
vxworks.
(LDEMUL_AFTER_OPEN): Don't set for vxworks.
(PARSE_AND_LIST_LONGOPTS, PARSE_AND_LIST_OPTIONS): Exclude
-secure-plt, -bss-plt and -sdata-got when vxworks.
This fixes the glaring error that the ppc476 workaround wasn't
actually enabled for ld -r, and adjusts relocations to match moved
code.
bfd/
* elf32-ppc.c (ppc_elf_relocate_section): Move relocs on insns
patched for ppc476 workaround. Reapply branch taken/not taken
relocs.
ld/
* emultempl/ppc32elf.em (ppc_after_open_output): Really enable
ppc476 workaround for ld -r.
The Linux kernel builds modules using ld -r. These might need the
ppc476 workaround, so enable it for ld -r if sections have sufficient
alignment to tell location within a page.
bfd/
* elf32-ppc.c (ppc_elf_relax_section): Enable ppc476 workaround
for ld -r, when code sections are sufficiently aligned.
* elf32-ppc.h (struct ppc_elf_params): Delete pagesize. Add
pagesize_p2.
ld/
* emultempl/ppc32elf.em (pagesize): New static var.
(ppc_after_open_output): Set params.pagesize_p2 from pagesize.
(PARSE_AND_LIST_ARGS_CASES): Adjust to use pagesize.
This implements a work-around for an icache bug on 476 that can cause
execution of stale instructions when control falls through from one
page to the next. The idea is to prevent such fall-through by
replacing the last instruction on a page with a branch to a patch
area containing the instruction, then branch to the next page.
The patch also fixes a number of bugs in the existing support for long
branch trampolines.
bfd/
* elf32-ppc.c (struct ppc_elf_link_hash_table): Add params.
Delete emit_stub_syms, no_tls_get_addr_opt. Update all uses.
(ppc_elf_link_params): New function.
(ppc_elf_create_glink): Align .glink to 64 bytes for ppc476
workaround.
(ppc_elf_select_plt_layout): Remove plt_style and emit_stub_syms
parameters. Use htab->params instead.
(ppc_elf_tls_setup): Remove no_tls_get_addr_opt parameter.
(ppc_elf_size_dynamic_sections): Align __glink_PLTresolve to
64 bytes for ppc476 workaround.
(struct ppc_elf_relax_info): New.
(ppc_elf_relax_section): Exclude linker created sections and
those too small to hold one instruction. Don't add another
branch around trampolines on later relax passes. Don't
generate trampolines for undefined symbols when !relocatable,
nor for plugin symbols. Allocate space for ppc476 workaround
patch area. Free fixups on error return path.
(ppc_elf_relocate_section): Handle ppc476 workaround patching.
* elf32-ppc.h (struct ppc_elf_params): New.
(ppc_elf_select_plt_layout, ppc_elf_tls_setup): Update prototype.
(ppc_elf_link_params): Declare.
* section.c (SEC_INFO_TYPE_TARGET): Define.
* bfd-in2.h: Regenerate.
ld/
* emultempl/ppc32elf.em (no_tls_get_addr_opt, emit_stub_syms)
plt_style): Delete. Adjust all refs to instead use..
(params): ..this. New variable.
(ppc_after_open_output): New function. Tweak params and pass to
ppc_elf_link_params.
(ppc_after_open): Adjust ppc_elf_select_plt_layout call.
(ppc_before_allocation): Adjust ppc_elf_tls_setup call. Enable
relaxation for ppc476 workaround.
(PARSE_AND_LIST_*): Add --{no-,}ppc476-workaround support.
(LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS): Define.
* ld.h (struct args_type): Rename 'relax' field to
'disable_target_specific_optimizations' and turn it into a
tri-state variable.
(RELAXATION_DISABLED_BY_DEFAULT): New macro.
(RELAXATION_DISABLED_BY_USER): New macro.
(RELAXATION_ENABLED): New macro.
(DISABLE_RELAXATION): New macro.
(ENABLE_RELAXATION): New macro.
* lexsup (enum option_values): Add OPTION_NO_RELAX.
(struct ld_options): Add --no-relax.
(parse_args): Handle OPTION_NO_RELAX. Use DISABLE_RELAXATION and
ENABLE_RELAXATION macros.
* ldlang.c (lang_relax_sections): Use RELAXATION_ENABLED macro.
(lang_process): Likewise.
* ldmain.c (main): Initialise
disable_target_specific_optimizations field.
(multiple_definition): Use RELAXATION_ENABLED macro.
* ld.texinfo: Document new command line option.
* emultempl/alphaelf.em: Remove --no-relax option.
(before_allocation): Test RELAXATION_DISABLED_BY_USER macro.
Use ENABLE_RELAXATION macro.
* emultempl/avrelf.em: (after_allocation): Test RELAXATION_ENABLED
macro.
* emultempl/cr16elf.em: Remove --no-relax option.
(before_allocation): Test RELAXATION_DISABLED_BY_USER macro.
Use ENABLE_RELAXATION macro.
* emultempl/crxelf.em: Remove --no-relax option.
(before_allocation): Test RELAXATION_DISABLED_BY_USER macro.
Use ENABLE_RELAXATION macro.
* emultempl/mmix-elfnmmo.em: (before_allocation): Use
ENABLE_RELAXATION macro.
* emultempl/needrelax.em: (before_allocation): Use
ENABLE_RELAXATION macro.
* emultempl/ppc32elf.em: (before_allocation): Test
RELAXATION_DISABLED_BY_DEFAULT macro. Use
ENABLE_RELAXATION macro.
* emultempl/sh64elf.em: (before_allocation): Test
RELAXATION_ENABLED macro. Use DISABLE_RELAXATION macro.
* emultempl/xtensaelf.em: Remove --no-relax option.
(before_allocation): Test RELAXATION_ENABLED macro.
Use ENABLE_RELAXATION macro.
* elf32-ppc.c (struct elf_linker_section): Remove sym_hash and
sym_offset. Add name, bss_name, sym_name, sym_val.
(struct ppc_elf_link_hash_table): Remove sdata and sdata2 pointers.
Add sdata array of elf_linker_section_t.
(ppc_elf_link_hash_table_create): Set name, sym_name, and bss_name.
(enum elf_linker_section_enum): Delete.
(ppc_elf_create_linker_section): Rewrite. Don't create syms here.
(ppc_elf_check_relocs): Delay ppc_elf_create_linker_section until
the special sections are needed. Adjust htab->sdata refs.
Ensure dynobj is set in sreloc code.
(ppc_elf_size_dynamic_sections): Strip sdata sections.
(ppc_elf_set_sdata_syms): New function.
(elf_finish_pointer_linker_section): Use 0x8000 for sym_offset.
(ppc_elf_relocate_section): Adjust references to htab->sdata. Use
sym_val instead of sym_hash.
* elf32-ppc.h (ppc_elf_set_sdata_syms): Declare.
ld/
* emultempl/ppc32elf.em (gld${EMULATION_NAME}_after_allocation): New
function.
(LDEMUL_AFTER_ALLOCATION): Define.
