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PR 23715
* dwarf2.c (find_abstract_instance): Allow recursive invocations
of find_abstract_instance to override the name variable.
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Inserted offset in final section in the GOT entry of type DTSOFF soon to be
relocated by the dynamic loader.
bfd/
2018-09-06 Cupertino Miranda <cmiranda@synopsys.com>
* arc-got.h (relocate_fix_got_relocs_for_got_info): Changed. Take TLS
section alignment in consideration for this relocation.
* elf32-arc.c (FINAL_SECTSTART): Added this formula macro.
(ARC_TLS_DTPOFF) Updated reloc to use new created macro instead.
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This patch fixes glibc testcase in nptl/tls-align.
bfd/
2018-08-01 Cupertino Miranda <cmiranda@synopsys.com>
* arc-got.h (relocate_fix_got_relocs_for_got_info): Changed, fixed
TCB_SIZE offsize to include section alignment.
* elf32-arc.c (arc_special_overflow_checks): Likewise.
include/
2018-08-01 Cupertino Miranda <cmiranda@synopsys.com>
* arc-reloc.def (ARC_TLS_LE_32): Updated reloc formula.
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A change upstream reveiled this issue, triggering an assert when linking glibc.
bfd/
2018-03-01 Cupertino Miranda <cmiranda@synopsys.com>
* elf32-arc.c (elf_arc_check_relocs): Changed.
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Problem identified in the context of glibc with latest upstream binutils.
Dynamic symbol space was being reserved but, no actual information for the
symbol was being set. Data for the symbol was kept initialized with -1.
No easy test case was possible to be created.
bfd/
2018-03-01 Cupertino Miranda <cmiranda@synopsys.com>
* elf32-arc.c (elf_arc_check_relocs): Changed.
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bfd/
2018-03-01 Cupertino Miranda <cmiranda@synopsys.com>
* elf32-arc.c (elf_arc_finish_dynamic_symbol) Return FALSE in case
arc_htab is NULL.
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Change location where GOT information is collected for ARC target, avoiding
posible use conflicts of the previous .got field in the symbols hash_entry.
bfd/
2018-03-01 Cupertino Miranda <cmiranda@synopsys.com>
* arc-got.h (get_got_entry_list_for_symbol): Changed.
* ef32-arc.c (struct elf_arc_link_hash_entry): Moved and changed.
(elf_arc_link_hash_newfunc): Changed.
(arc_elf_link_hash_table_create): Removed old initializations.
(elf_arc_relocate_section, elf_arc_finish_dynamic_symbol): Changed.
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elfclass has been set to bed->s->elfclass earlier.
* elf-properties.c (_bfd_elf_link_setup_gnu_properties): Use
elfclass instead of bed->s->elfclass.
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bfd/
* elfnn-riscv.c (riscv_init_pcgp_relocs): Add explanatory comment.
(riscv_free_pcgp_relocs, riscv_record_pcgp_reloc): Likewise.
(riscv_find_pcgp_hi_reloc, riscv_reocrd_pcgp_lo_reloc): Likewise.
(riscv_find_pcgp_lo_reloc): Likewise.
(riscv_delete_pcgp_hi_reloc, riscv_use_pcgp_hi_reloc): Delete.
(riscv_delete_pcgp_lo_reloc): Likewise.
(_bfd_riscv_relax_pc): Don't call riscv_use_pcgp_hi_reloc. Replace
calls to riscv_delete_pcgp_lo_reloc and riscv_delete_pcgp_hi_reloc
with TRUE. Mark abfd arg as ATTRIBUTE_UNUSED.
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It is unused, removing it fixes this error when building with clang:
/home/emaisin/src/binutils-gdb/bfd/elf32-nds32.c:3172:1: error: unused function 'elf32_nds32_allocate_dynrelocs' [-Werror,-Wunused-function]
elf32_nds32_allocate_dynrelocs (struct bfd_link_info *info, asection *sreloc,
^
1 error generated.
gcc only reports the error if you remove "inline". I don't know if this
is actually a mistake and it should actually be used though.
gdb/ChangeLog:
* elf32-nds32.c (elf32_nds32_allocate_dynrelocs): Remove.
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bfd/
* elfnn-riscv.c (riscv_make_plt_header): New arg output_bfd. Change
return type to bfd_boolean. If EF_RISCV_RVE call _bfd_error_handler
and return FALSE. Return TRUE at end.
(riscv_make_plt_entry): Likewise.
(riscv_elf_finish_dynamic_symbol): Update call to riscv_make_plt_entry.
(riscv_elf_finish_dynamic_sections): Update call to
riscv_make_plt_header.
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bfd/
* elfnn-riscv.c (_bfd_riscv_relax_pc) <R_RISCV_PCREL_LO12_I>: New local
hi_sec_off which is symbol address with addend subtracted. Use in
riscv_find_pcgp_hi_reloc and riscv_record_pcgp_lo_reloc calls.
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bfd/
* elfnn-riscv.c (riscv_resolve_pcrel_lo_relocs): Add check for reloc
overflow with addend. Use reloc_dangerous instead of reloc_overflow.
Add strings for the two errors handled here.
(riscv_elf_relocate_section) In case R_RISCV_PCREL_LO12_I, rewrite
comment. Only give error with addend when used with section symbol.
In case bfd_reloc_dangerous, update error string.
ld/
* testsuite/ld-riscv-elf/ld-riscv-elf.exp: Run pcrel-lo-addend-2.
* testsuite/ld-riscv/elf/ld-riscv-elf/pcrel-lo-addend-2.d: New.
* testsuite/ld-riscv/elf/ld-riscv-elf/pcrel-lo-addend-2.s: New.
* testsuite/ld-riscv/elf/ld-riscv-elf/pcrel-lo-addend.d: Update name
and error string.
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When opening a BFD for update, as gdb --write does, modifications to
anything but the contents of sections is restricted.
Do not try to write back any ELF headers in this case.
bfd/ChangeLog
2018-09-24 Jozef Lawrynowicz <jozef.l@mittosystems.com>
PR gdb/20948
* elf.c (_bfd_elf_write_object_contents): Return from function
early if abfd->direction == both_direction.
gdb/testsuite/ChangeLog
2018-09-24 Jozef Lawrynowicz <jozef.l@mittosystems.com>
PR gdb/20948
* gdb.base/write_mem.exp: New test.
* gdb.base/write_mem.c: Likewise.
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The fls function already exists on macOS and FreeBSD (and probably others),
leading to this error:
/Users/simark/src/binutils-gdb/bfd/elf32-nds32.c:5074:1: error: static declaration of 'fls' follows non-static declaration
fls (register unsigned int x)
^
/usr/include/strings.h:87:6: note: previous declaration is here
int fls(int) __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);
^
Add a configure-time check for it, and only define it if the system doesn't
provide it.
bfd/ChangeLog:
* configure.ac: Check for fls.
* elf32-nds32.c (fls): Only define if !HAVE_FLS.
* config.in: Re-generate.
* configure: Re-generate.
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Remove duplicate `rs6000-*-aix5.[01]' and `rs6000-*-aix[5-9]*' target
configuration selectors meant to correspond to `powerpc64-*-aix5.[01]'
and `powerpc64-*-aix[5-9]*' respectively for the purpose of BFD target
vector selection in `config.bfd'.
These selectors were added with commit 9a9e2ca33263 ("rs6000 xcoff bfd
config"), <https://sourceware.org/ml/binutils/2010-12/msg00372.html>,
and have been dead right from the beginning, because they appear twice
each in the case statement, which means the earlier instance of each
takes precedence and the other one is ignored. Here ones that alias to
`powerpc-*-aix5.[01]' and `powerpc-*-aix[5-9]*' respectively immediately
above are used instead.
bfd/
* config.bfd <rs6000-*-aix5.[01], rs6000-*-aix[5-9]*>: Remove
duplicate `case' selectors.
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binutils on upstream!
We have not only removed all unsupported and obsolete code, but also supported lost of new features,
including better link-time relaxations and TLS implementations. Besides, the files generated by the
newly assembler and linker usually get higher performance and more optimized code size.
ld * emultempl/nds32elf.em (hyper_relax): New variable.
(nds32_elf_create_output_section_statements):
the parameters of bfd_elf32_nds32_set_target_option
(PARSE_AND_LIST_PROLOGUE, PARSE_AND_LIST_OPTIONS,
PARSE_AND_LIST_ARGS_CASES): Add new option --mhyper-relax.
* emultempl/nds32elf.em (nds32_elf_after_open): Updated.
* emultempl/nds32elf.em (tls_desc_trampoline): New variable.
* (nds32_elf_create_output_section_statements): Updated.
* (nds32_elf_after_parse): Disable relaxations when PIC is enable.
* (PARSE_AND_LIST_PROLOGUE, PARSE_AND_LIST_OPTIONS,
PARSE_AND_LIST_ARGS_CASES): Add new option --m[no-]tlsdesc-trampoline.
include * elf/nds32.h: Remove the unused target features.
* dis-asm.h (disassemble_init_nds32): Declared.
* elf/nds32.h (E_NDS32_NULL): Removed.
(E_NDS32_HAS_DSP_INST, E_NDS32_HAS_ZOL): New.
* opcode/nds32.h: Ident.
(N32_SUB6, INSN_LW): New macros.
(enum n32_opcodes): Updated.
* elf/nds32.h: Doc fixes.
* elf/nds32.h: Add R_NDS32_LSI.
* elf/nds32.h: Add new relocations for TLS.
gas * config/tc-nds32.c: Remove the unused target features.
(nds32_relax_relocs, md_pseudo_table, nds32_elf_record_fixup_exp,
nds32_set_elf_flags_by_insn, nds32_insert_relax_entry,
nds32_apply_fix): Likewise.
(nds32_no_ex9_begin): Removed.
* config/tc-nds32.c (add_mapping_symbol_for_align,
make_mapping_symbol, add_mapping_symbol): New functions.
* config/tc-nds32.h (enum mstate): New.
(nds32_segment_info_type): Likewise.
* configure.ac (--enable-dsp-ext, --enable-zol-ext): New options.
* config.in: Regenerated.
* configure: Regenerated.
* config/tc-nds32.c (nds32_dx_regs):
Set the value according to the configuration.
(nds32_perf_ext, nds32_perf_ext2, nds32_string_ext, nds32_audio_ext):
Likewise.
(nds32_dsp_ext): New variable. Set the value according to the
configuration.
(nds32_zol_ext): Likewise.
(asm_desc, nds32_pseudo_opcode_table): Make them static.
(nds32_set_elf_flags_by_insn): Updated.
(nds32_check_insn_available): Updated.
(nds32_str_tolower): New function.
* config/tc-nds32.c (relax_table): Updated.
(md_begin): Updated.
(md_assemble): Use XNEW macro to allocate space for `insn.info',
and then remember to free it.
(md_section_align): Cast (-1) to ValueT.
(nds32_get_align): Cast (~0U) to addressT.
(nds32_relax_branch_instructions): Updated.
(md_convert_frag): Add new local variable `final_r_type'.
(invalid_prev_frag): Add new bfd_boolean parameter `relax'.
All callers changed.
* config/tc-nds32.c (struct nds32_relocs_pattern): Add `insn' field.
(struct nds32_hint_map): Add `option_list' field.
(struct suffix_name, suffix_table): Remove the unused `pic' field.
(do_pseudo_b, do_pseudo_bal): Remove the suffix checking.
(do_pseudo_la_internal, do_pseudo_pushpopm): Indent.
(relax_hint_bias, relax_hint_id_current): New static variables.
(reset_bias, relax_hint_begin): New variables.
(nds_itoa): New function.
(CLEAN_REG, GET_OPCODE): New macros.
(struct relax_hint_id): New.
(nds32_relax_hint): For .relax_hint directive, we can use `begin'
and `end' to mark the relax pattern without giving exactly id number.
(nds32_elf_append_relax_relocs): Handle the case that the .relax_hint
directives are attached to pseudo instruction.
(nds32_elf_save_pseudo_pattern): Change the second parameter from
instruction's opcode to byte code.
(nds32_elf_build_relax_relation): Add new bfd_boolean parameter
`pseudo_hint'.
(nds32_lookup_pseudo_opcode): Fix the overflow issue.
(enum nds32_insn_type): Add N32_RELAX_ALU1 and N32_RELAX_16BIT.
(nds32_elf_record_fixup_exp, relax_ls_table, hint_map,
nds32_find_reloc_table, nds32_match_hint_insn, nds32_parse_name):
Updated.
* config/tc-nds32.h (MAX_RELAX_NUM): Extend it to 6.
(enum nds32_relax_hint_type): Merge NDS32_RELAX_HINT_LA and
NDS32_RELAX_HINT_LS into NDS32_RELAX_HINT_LALS. Add
NDS32_RELAX_HINT_LA_PLT, NDS32_RELAX_HINT_LA_GOT and
NDS32_RELAX_HINT_LA_GOTOFF.
* config/tc-nds32.h (relax_ls_table): Add floating load/store
to gp relax pattern.
(hint_map, nds32_find_reloc_table): Likewise.
* configure.ac: Define NDS32_LINUX_TOOLCHAIN.
* configure: Regenerated.
* config.in: Regenerated.
* config/tc-nds32.h (enum nds32_ramp): Updated.
(enum nds32_relax_hint_type): Likewise.
* config/tc-nds32.c: Include "errno.h" and "limits.h".
(relax_ls_table): Add TLS relax patterns.
(nds32_elf_append_relax_relocs): Attach BFD_RELOC_NDS32_GROUP on
each instructions of TLS patterns.
(nds32_elf_record_fixup_exp): Updated.
(nds32_apply_fix): Likewise.
(suffix_table): Add TLSDESC suffix.
binutils* testsuite/binutils-all/objcopy.exp: Set the unsupported reloc number
from 215 to 255 for NDS32.
bfd * elf32-nds32.c (nds32_elf_relax_loadstore):
Remove the unused target features.
(bfd_elf32_nds32_set_target_option): Remove the unused parameters.
(nds32_elf_relax_piclo12, nds32_elf_relax_letlslo12,
nds32_elf_relax_letlsadd, nds32_elf_relax_letlsls,
nds32_elf_relax_pltgot_suff, nds32_elf_relax_got_suff
nds32_elf_relax_gotoff_suff, calculate_plt_memory_address,
calculate_plt_offset, calculate_got_memory_address,
nds32_elf_check_dup_relocs): Removed.
All callers changed.
* elf32-nds32.h: Remove the unused macros and defines.
(elf_nds32_link_hash_table): Remove the unused variable.
(bfd_elf32_nds32_set_target_option): Update prototype.
(nds32_elf_ex9_init): Removed.
* elf32-nds32.c (nds32_convert_32_to_16): Updated.
* elf32-nds32.c (HOWTO2, HOWTO3): Define new HOWTO macros
to initialize array nds32_elf_howto_table in any order
without lots of EMPTY_HOWTO.
(nds32_reloc_map): Updated.
* reloc.c: Add BFD_RELOC_NDS32_LSI.
* bfd-in2.h: Regenerated.
* bfd/libbfd.h: Regenerated.
* elf32-nds32.c (nds32_elf_relax_howto_table): Add R_NDS32_LSI.
(nds32_reloc_map): Likewise.
(nds32_elf_relax_flsi): New function.
(nds32_elf_relax_section): Support floating load/store relaxation.
* elf32-nds32.c (NDS32_GUARD_SEC_P, elf32_nds32_local_gp_offset):
New macro.
(struct elf_nds32_link_hash_entry): New `offset_to_gp' field.
(struct elf_nds32_obj_tdata): New `offset_to_gp' and `hdr_size' fields.
(elf32_nds32_allocate_local_sym_info, nds32_elf_relax_guard,
nds32_elf_is_target_special_symbol, nds32_elf_maybe_function_sym):
New functions.
(nds32_info_to_howto_rel): Add BFD_ASSERT.
(bfd_elf32_bfd_reloc_type_table_lookup, nds32_elf_link_hash_newfunc,
nds32_elf_link_hash_table_create, nds32_elf_relocate_section,
nds32_elf_relax_loadstore, nds32_elf_relax_lo12, nds32_relax_adjust_label,
bfd_elf32_nds32_set_target_option, nds32_fag_mark_relax): Updated.
(nds32_elf_final_sda_base): Improve it to find the better gp value.
(insert_nds32_elf_blank): Must consider `len' when inserting blanks.
* elf32-nds32.h (bfd_elf32_nds32_set_target_option): Update prototype.
(struct elf_nds32_link_hash_table): Add new variable `hyper_relax'.
* elf32-nds32.c (elf32_nds32_allocate_dynrelocs): New function.
(create_got_section): Likewise.
(allocate_dynrelocs, nds32_elf_size_dynamic_sections,
nds32_elf_relocate_section, nds32_elf_finish_dynamic_symbol): Updated.
(nds32_elf_check_relocs): Fix the issue that the shared library may
has TEXTREL entry in the dynamic section.
(nds32_elf_create_dynamic_sections): Enable to call readonly_dynrelocs
since the TEXTREL issue is fixed in the nds32_elf_check_relocs.
(nds32_elf_finish_dynamic_sections): Update and add DT_RELASZ
dynamic entry.
(calculate_offset): Remove the unused parameter `pic_ext_target' and
related codes.
All callers changed.
(elf_backend_dtrel_excludes_plt): Disable it temporarily since it
will cause some errors for our test cases.
* elf32-nds32.c (nds32_elf_merge_private_bfd_data): Allow to link the
generic object.
* reloc.c: Add TLS relocations.
* libbfd.h: Regenerated.
* bfd-in2.h: Regenerated.
* elf32-nds32.h (struct section_id_list_t): New.
(elf32_nds32_lookup_section_id, elf32_nds32_check_relax_group,
elf32_nds32_unify_relax_group, nds32_elf_unify_tls_model):
New prototypes.
(elf32_nds32_compute_jump_table_size, elf32_nds32_local_tlsdesc_gotent):
New macro.
(nds32_insertion_sort, bfd_elf32_nds32_set_target_option,
elf_nds32_link_hash_table): Updated.
* elf32-nds32.c (enum elf_nds32_tls_type): New.
(struct elf32_nds32_relax_group_t, struct relax_group_list_t): New.
(elf32_nds32_add_dynreloc, patch_tls_desc_to_ie, get_tls_type,
fls, ones32, list_insert, list_insert_sibling, dump_chain,
elf32_nds32_check_relax_group, elf32_nds32_lookup_section_id,
elf32_nds32_unify_relax_group, nds32_elf_unify_tls_model): New functions.
(elf_nds32_obj_tdata): Add new fields.
(elf32_nds32_relax_group_ptr, nds32_elf_local_tlsdesc_gotent): New macros.
(nds32_elf_howto_table): Add TLS relocations.
(nds32_reloc_map): Likewise.
(nds32_elf_copy_indirect_symbol, nds32_elf_size_dynamic_sections,
nds32_elf_finish_dynamic_symbol, elf32_nds32_allocate_local_sym_info,
nds32_elf_relocate_section, bfd_elf32_nds32_set_target_option,
nds32_elf_check_relocs, allocate_dynrelocs): Updated.
(nds32_elf_relax_section): Call nds32_elf_unify_tls_model.
(dtpoff_base): Rename it to `gottpof' and then update it.
opcodes * nds32-asm.c (operand_fields): Remove the unused fields.
(nds32_opcodes): Remove the unused instructions.
* nds32-dis.c (nds32_ex9_info): Removed.
(nds32_parse_opcode): Updated.
(print_insn_nds32): Likewise.
* nds32-asm.c (config.h, stdlib.h, string.h): New includes.
(LEX_SET_FIELD, LEX_GET_FIELD): Update defines.
(nds32_asm_init, build_operand_hash_table, build_keyword_hash_table,
build_opcode_hash_table): New functions.
(nds32_keyword_table, nds32_keyword_count_table, nds32_field_table,
nds32_opcode_table): New.
(hw_ktabs): Declare it to a pointer rather than an array.
(build_hash_table): Removed.
* nds32-asm.h (enum): Add SYN_INPUT, SYN_OUTPUT, SYN_LOPT,
SYN_ROPT and upadte HW_GPR and HW_INT.
* nds32-dis.c (keywords): Remove const.
(match_field): New function.
(nds32_parse_opcode): Updated.
* disassemble.c (disassemble_init_for_target):
Add disassemble_init_nds32.
* nds32-dis.c (eum map_type): New.
(nds32_private_data): Likewise.
(get_mapping_symbol_type, is_mapping_symbol, nds32_symbol_is_valid,
nds32_add_opcode_hash_table, disassemble_init_nds32): New functions.
(print_insn_nds32): Updated.
* nds32-asm.c (parse_aext_reg): Add new parameter.
(parse_re, parse_re2, parse_aext_reg): Only reduced registers
are allowed to use.
All callers changed.
* nds32-asm.c (keyword_usr, keyword_sr): Updated.
(operand_fields): Add new fields.
(nds32_opcodes): Add new instructions.
(keyword_aridxi_mx): New keyword.
* nds32-asm.h (enum): Add NASM_ATTR_DSP_ISAEXT, HW_AEXT_ARIDXI_MX
and NASM_ATTR_ZOL.
(ALU2_1, ALU2_2, ALU2_3): New macros.
* nds32-dis.c (nds32_filter_unknown_insn): Updated.
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PR 23685
* peXXigen.c (pe_print_edata): Correct export address table
overflow checks. Check dataoff against section size too.
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Fixes the bugs exposed by the testcases in the PR, plus two more bugs
I noticed when looking at _bfd_stab_section_find_nearest_line.
PR 23686
* dwarf2.c (read_section): Error when attempting to malloc
"(bfd_size_type) -1".
* syms.c (_bfd_stab_section_find_nearest_line): Bounds check
function_name. Bounds check reloc address. Formatting. Ensure
.stabstr zero terminated.
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invalid section size.
PR 23657
* elfcode.h (elf_swap_shdr_in): Generate a warning message if an
ELF section has contents and size larger than the file size.
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When dereferencing a GOT slot with lgrl or lg we rewrite this using
larl to get rid of the extra memory access. However, we cannot do
this for:
- symbols marked for absolute addressing
- symbols at odd addresses (larl can handle only even addresses)
Fixed with the attached patch.
bfd/ChangeLog:
2018-09-17 Andreas Krebbel <krebbel@linux.ibm.com>
* elf64-s390.c (elf_s390_relocate_section): Prevent rewriting of
GOT accesses with larl for ABS or misaligned symbols.
ld/ChangeLog:
2018-09-17 Andreas Krebbel <krebbel@linux.ibm.com>
* testsuite/ld-s390/gotreloc-1.s: Add tests for ABS and misaligned
symbol. Move variables into data section. Make bar 8 bytes wide.
* testsuite/ld-s390/gotreloc-1.ver: Make misaligned_sym resolve locally.
* testsuite/ld-s390/gotreloc_31-1.dd: Adjust patterns.
* testsuite/ld-s390/gotreloc_64-norelro-1.dd: Likewise.
* testsuite/ld-s390/gotreloc_64-relro-1.dd: Likewise.
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* bfd/elf32-s12z.c (bfd_elf32_bfd_reloc_name_lookup): Remove diagnostic printf
(artifact from debugging)
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Thanks to Alan Modra for this hint.
* bfd/elf32-s12z.c (elf_s12z_howto_table): set all src_mask members to zero.
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We have an issue in the MIPS backend, with the handling of undefined
hidden and internal weak symbols. References to such symbols are
supposed to resolve to 0 according to the ELF gABI[1]:
"Unresolved weak symbols have a zero value."
and the 64-bit MIPS psABI[2]:
"If a symbol with one of these [hidden or internal] attributes has no
definition within the executable/DSO being linked, then it must be
resolved to allocated space if common, resolved to zero if weak, or an
error reported otherwise."
however if a GOT relocation is used, then a local GOT entry is created
and used to satisfy the reference. Such an entry is then (in DSO and
PIE binaries) subject to the usual load-time relocation, which means a
non-zero value will be returned if the base address is non-zero. This
will defeat the usual run-time sequence like:
void a (void) __attribute__ ((visibility ("hidden"), weak));
void
x (void)
{
if (a)
a ();
}
This can be reproduced with this simple code:
$ cat libtest.c
extern int a __attribute__ ((visibility ("hidden"), weak));
int *
x (void)
{
return &a;
}
$ cat test.c
int *x (void);
int
main (void)
{
printf ("a: %p\n", x ());
return 0;
}
$ gcc -shared -fPIC -o libtest.so libtest.c
$ gcc -o test test.c -Wl,-rpath,$(pwd) libtest.so
$ ./test
a: 0x77184000
$
The usual approach targets take is making all the steps required to
assign a GOT entry for the symbol referred, and then leave its contents
at zero with no dynamic relocation attached, therefore ensuring that the
value does not change at load time. However this is not going to work
with the implicitly relocated GOT the MIPS psABI specifies[3]:
"The dynamic linker relocates the global offset table by first adding
the difference between the base where the shared object is loaded and
the value of the dynamic tag DT_MIPS_BASE_ADDRESS to all local global
offset table entries."
and we cannot therefore use the local GOT part.
And we cannot offhand use the global part either, as the symbol would
then have to be exported and possibly wrongly preempt symbols in other
modules involved in the dynamic load, because as per the ELF gABI[1] we
are not allowed to enter a hidden or internal symbol into the dynamic
symbol table (and then use its associated GOT entry):
"A hidden symbol contained in a relocatable object must be either
removed or converted to STB_LOCAL binding by the link-editor when the
relocatable object is included in an executable file or shared object."
and:
"An internal symbol contained in a relocatable object must be either
removed or converted to STB_LOCAL binding by the link-editor when the
relocatable object is included in an executable file or shared object."
So we have to choose something else.
Our choice is further limited by the need for the reference associated
with the GOT relocation to stay within the signed 16-bit limit from the
GOT pointer base register, while being compliant with the ELF gABI and
the MIPS psABI. However as Alan Modra has observed[4] one possibility
is to edit (relax) the code such that the GOT reference is removed
altogether.
Based on these observations then modify MIPS BFD linker backend code to:
1. Interpret code associated with GOT relocations and relax the usual LW
or LD instructions into a corresponding immediate load operation that
places the value of 0 in the intended register, while leaving the GOT
entry allocated and initialized as usually.
2. Leave any other instructions associated with GOT relocations in place
and instead redirect the reference to a global GOT entry associated
with a special `__gnu_absolute_zero' symbol created for this purpose,
whose value is 0, SHN_ABS section marks it absolute, binding is
global and export class protected, ensuring that the locally provided
value is always used at load time, and that the value is not
relocated by the dynamic loader.
3. Adjust any high-part GOT relocation used, typically associated with
a LUI instruction, accordingly, so that run-time consistency is
maintained, either by resolving to the original entry if the
instruction associated with the corresponding low-part GOT relocation
has been relaxed to an immediate load (in which case the value loaded
with LUI will be overwritten), or by also redirecting the reference
to `__gnu_absolute_zero' to complete the GOT access sequence if that
symbol has been used.
4. Add a target `elf_backend_hide_symbol' hook, for the three MIPS ABIs,
which prevents the `__gnu_absolute_zero' symbol from being forced
local, to ensure that the redirection works and the symbol remains
global/protected with existing linker scripts unchanged.
5. Observing the issue with handling SHN_ABS symbols in the GNU dynamic
loader, covered by glibc PR 19818, set the EI_ABIVERSION field in the
ELF file header produced to 4 (ABI_ABSOLUTE) if `__gnu_absolute_zero'
symbol has been produced and the target configured indicates the GNU
operating system, so that broken versions of the GNU dynamic loader
gracefully reject the file in loading rather than going astray. Keep
EI_ABIVERSION at the original value for other operating systems or if
no `__gnu_absolute_zero' symbol has been made.
The name of the special `__gnu_absolute_zero' has no meaning other than
how a human reader can interpret it, as it is ignored in dynamic loading
in the handling of the scenarios concerned. This is because the symbol
resolves locally, and it's only the symbol's attributes that matter so
that the associated GOT entry remains unchanged at load time.
Therefore the name is somewhat arbitrary, observing however the need to
use the name space reserved for the system so that it does not conflict
with a possible user symbol, and hence the leading underscore, and also
the `gnu' infix to denote a GNU feature. Other implementations wishing
to address the problem in a similar way may choose a different name and
have the solution still work, possibly with a mixture of modules used in
a dynamic having symbols of different names provided, which will however
not interact with each other due to the protected export class.
The symbol can be referred explicitly, however the name is an internal
implementation detail rather than a part of the ABI, and therefore no
specific semantics is guaranteed.
One limitation of this change is that if `__gnu_absolute_zero' has been
already defined, then we do not wipe the old definition and all kinds of
odd behavior can result. This is however like with other symbols we
internally define, such as `_GLOBAL_OFFSET_TABLE_' or `__rld_map', and
therefore left as a possible future enhancement.
As an optimization the relaxation of LW and LD instructions to a load of
immediate zero is always made, even SVR4 PIC code for code that will end
up in a regular (non-PIE) executable, because there is a cache advantage
with the avoidance of a load from the GOT, even if it is otherwise
guaranteed to remain zero. It does not reliably happen though, due to a
symbol exportation issue affecting executables, covered by PR ld/21805.
One existing test case needs to be updated, as it triggers relaxation
introduced with this change and consequently linker output does not
match expectations anymore. As we want to keep the original issue
covered with the test case modify it then to use the LWL instruction in
place of LW, and adjust the output expected accordingly.
References:
[1] "System V Application Binary Interface - DRAFT - 19 October 2010",
The SCO Group, Section "Symbol Table",
<http://www.sco.com/developers/gabi/2012-12-31/ch4.symtab.html>
[2] "64-bit ELF Object File Specification, Draft Version 2.5", MIPS
Technologies / Silicon Graphics Computer Systems, Order Number
007-4658-001, Section 2.5 "Symbol Table", p. 22,
<http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf>
[3] "SYSTEM V APPLICATION BINARY INTERFACE, MIPS RISC Processor
Supplement, 3rd Edition", Section "Global Offset Table", p. 5-10,
<http://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf>
[4] "Undo dynamic symbol state after regular object sym type mismatch",
<https://sourceware.org/ml/binutils/2017-07/msg00265.html>
bfd/
PR ld/21375
* elfxx-mips.h (_bfd_mips_elf_hide_symbol): New prototype.
(_bfd_mips_elf_linker_flags): Update prototype.
* elf32-mips.c (elf_backend_hide_symbol): New macro.
* elf64-mips.c (elf_backend_hide_symbol): Likewise.
* elfn32-mips.c (elf_backend_hide_symbol): Likewise.
* elfxx-mips.c (mips_elf_link_hash_table): Add
`use_absolute_zero' and `gnu_target' members.
(mips_elf_record_global_got_symbol): Call
`_bfd_mips_elf_hide_symbol' rather than
`_bfd_elf_link_hash_hide_symbol'.
(mips_use_local_got_p): Return FALSE if the symbol is absolute.
(mips_elf_obtain_contents): Reorder function.
(mips_elf_nullify_got_load): New function.
(mips_elf_calculate_relocation): Add `contents' parameter.
Nullify GOT loads or if it is not possible, then redirect GOT
relocations to the `__gnu_absolute_zero' symbol, for references
that are supposed to resolve to zero.
(mips_elf_define_absolute_zero): New function.
(_bfd_mips_elf_check_relocs): Prepare for arrangements made in
`mips_elf_calculate_relocation' for references made via the GOT
that are supposed to resolve to zero.
(_bfd_mips_elf_hide_symbol): New function.
(_bfd_mips_elf_linker_flags): Add the `gnu_target' parameter,
set the `gnu_target' member of the MIPS hash table.
(MIPS_LIBC_ABI_ABSOLUTE): New enumeration constant.
(_bfd_mips_post_process_headers): Use it.
ld/
PR ld/21375
* emultempl/mipself.em: Set `gnu_target' according to ${target}.
(mips_create_output_section_statements): Update call to
`_bfd_mips_elf_linker_flags'.
* testsuite/ld-mips-elf/pr21334.s: Use LWL rather than LW.
* testsuite/ld-mips-elf/pr21334.dd: Update accordingly.
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Move code used to store the contents of a relocated field in output into
a separate function, `mips_elf_store_contents', complementing existing
`mips_elf_obtain_contents'.
bfd/
* elfxx-mips.c (mips_elf_store_contents): New function...
(mips_elf_perform_relocation): ... factored out from here.
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Define DIFF_EXPR_OK to Support PC relative diff relocation,
and add CKCORE_PCREL32 relocation process
bfd/
* elf32-csky.c (csky_elf_howto_table): Fill special_function of
R_CKCORE_PCREL32.
(csky_elf_relocate_section): Add R_CKCORE_PCREL32 process.
gas/
* config/tc-csky.c (md_apply_fix): Transmit
BFD_RELOC_32_PCREL to BFD_RELOC_CKCORE_PCREL32.
(tc_gen_reloc): Trasmit BFD_RELOC_CKCORE_ADDR32 to
BFD_RELOC_CKCORE_PCREL32 while pc-relative.
* config/tc-csky.h (DIFF_EXPR_OK): Define to enable PC relative
diff relocs.
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dwarf2.c code reasonably assumes that debug info is local to a file,
an assumption now violated by gcc, resulting in "DWARF error: invalid
abstract instance DIE ref" or wrong details when attempting to print
linker error messages with file, function and line reported.
This is because find_abstract_instance is only prepared to handle
DW_FORM_ref_addr when the .debug_info section referenced is in the
current file. When that isn't the case, relocations to access another
file's .debug_info will typically be against a symbol defined at the
start of that .debug_info section, plus an addend. Since the dwarf2.c
code only considers the current file's debug info, that symbol will be
undefined, resolving to zero. In effect the ref_addr will wrongly
resolve to the current file's .debug_info.
This patch avoids the problem by treating relocations in debug
sections against undefined symbols in a similar manner to the way
relocations against symbols defined in discarded sections are
resolved. They result in a zero value (except in .debug_ranges)
regardless of the addend.
PR 23425
* reloc.c (bfd_generic_get_relocated_section_contents): Zero reloc
fields in debug sections when reloc is against an undefined symbol
and called from bfd_simple_get_relocated_section_contents or
similar.
* dwarf2.c (find_abstract_instance): Return true for zero offset
DW_FORM_ref_addr without returning values.
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