Variables defined in shared libraries are copied into an executable's
.bss section when code in the executable is non-PIC and thus would
require dynamic text relocations to access the variable directly in
the shared library. Recent x86 toolchains also copy variables into
the executable to gain a small speed improvement.
The problem is that if the variable was originally read-only, the copy
in .bss is writable, potentially opening a security hole. This patch
cures that problem by putting the copy in a section that becomes
read-only after ld.so relocation, provided -z relro is in force.
The patch also fixes a microblaze linker segfault on attempting to
use dynamic bss variables.
bfd/
PR ld/20995
* elf-bfd.h (struct elf_link_hash_table): Add sdynrelro and
sreldynrelro.
(struct elf_backend_data): Add want_dynrelro.
* elfxx-target.h (elf_backend_want_dynrelro): Define.
(elfNN_bed): Update initializer.
* elflink.c (_bfd_elf_create_dynamic_sections): Create
sdynrelro and sreldynrelro sections.
* elf32-arm.c (elf32_arm_adjust_dynamic_symbol): Place variables
copied into the executable from read-only sections into sdynrelro.
(elf32_arm_size_dynamic_sections): Handle sdynrelro.
(elf32_arm_finish_dynamic_symbol): Select sreldynrelro for
dynamic relocs in sdynrelro.
(elf_backend_want_dynrelro): Define.
* elf32-hppa.c (elf32_hppa_adjust_dynamic_symbol)
(elf32_hppa_size_dynamic_sections, elf32_hppa_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-i386.c (elf_i386_adjust_dynamic_symbol)
(elf_i386_size_dynamic_sections, elf_i386_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-metag.c (elf_metag_adjust_dynamic_symbol)
(elf_metag_size_dynamic_sections, elf_metag_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol)
(microblaze_elf_size_dynamic_sections)
(microblaze_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-nios2.c (nios2_elf32_finish_dynamic_symbol)
(nios2_elf32_adjust_dynamic_symbol)
(nios2_elf32_size_dynamic_sections)
(elf_backend_want_dynrelro): As above.
* elf32-or1k.c (or1k_elf_finish_dynamic_symbol)
(or1k_elf_adjust_dynamic_symbol, or1k_elf_size_dynamic_sections)
(elf_backend_want_dynrelro): As above.
* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol)
(ppc_elf_size_dynamic_sections, ppc_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-s390.c (elf_s390_adjust_dynamic_symbol)
(elf_s390_size_dynamic_sections, elf_s390_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-tic6x.c (elf32_tic6x_adjust_dynamic_symbol)
(elf32_tic6x_size_dynamic_sections)
(elf32_tic6x_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-tilepro.c (tilepro_elf_adjust_dynamic_symbol)
(tilepro_elf_size_dynamic_sections)
(tilepro_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol)
(ppc64_elf_size_dynamic_sections, ppc64_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf64-s390.c (elf_s390_adjust_dynamic_symbol)
(elf_s390_size_dynamic_sections, elf_s390_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf64-x86-64.c (elf_x86_64_adjust_dynamic_symbol)
(elf_x86_64_size_dynamic_sections)
(elf_x86_64_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elfnn-aarch64.c (elfNN_aarch64_adjust_dynamic_symbol)
(elfNN_aarch64_size_dynamic_sections)
(elfNN_aarch64_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elfnn-riscv.c (riscv_elf_adjust_dynamic_symbol)
(riscv_elf_size_dynamic_sections, riscv_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elfxx-mips.c (_bfd_mips_elf_adjust_dynamic_symbol)
(_bfd_mips_elf_size_dynamic_sections)
(_bfd_mips_vxworks_finish_dynamic_symbol): As above.
* elfxx-sparc.c (_bfd_sparc_elf_adjust_dynamic_symbol)
(_bfd_sparc_elf_size_dynamic_sections)
(_bfd_sparc_elf_finish_dynamic_symbol): As above.
* elfxx-tilegx.c (tilegx_elf_adjust_dynamic_symbol)
(tilegx_elf_size_dynamic_sections)
(tilegx_elf_finish_dynamic_symbol): As above.
* elf32-mips.c (elf_backend_want_dynrelro): Define.
* elf64-mips.c (elf_backend_want_dynrelro): Define.
* elf32-sparc.c (elf_backend_want_dynrelro): Define.
* elf64-sparc.c (elf_backend_want_dynrelro): Define.
* elf32-tilegx.c (elf_backend_want_dynrelro): Define.
* elf64-tilegx.c (elf_backend_want_dynrelro): Define.
* elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol): Tidy.
(microblaze_elf_size_dynamic_sections): Handle sdynbss.
* elf32-nios2.c (nios2_elf32_size_dynamic_sections): Make use
of linker shortcuts to dynamic sections rather than comparing
names. Correctly set "got" flag.
ld/
PR ld/20995
* testsuite/ld-arm/farcall-mixed-app-v5.d: Update to suit changed
stub hash table traversal caused by section id increment. Accept
the previous output too.
* testsuite/ld-arm/farcall-mixed-app.d: Likewise.
* testsuite/ld-arm/farcall-mixed-lib-v4t.d: Likewise.
* testsuite/ld-arm/farcall-mixed-lib.d: Likewise.
* testsuite/ld-elf/pr20995a.s, * testsuite/ld-elf/pr20995b.s,
* testsuite/ld-elf/pr20995.r: New test.
* testsuite/ld-elf/elf.exp: Run it.
With this change all gas and most ld tests pass when configured for
arm-linux. It doesn't look like these configurations have been
tested in a long time but this attempts to stem the bit-rot slightly.
gas/testsuite/ChangeLog:
2014-07-10 Will Newton <will.newton@linaro.org>
* gas/arm/bl-local-2.d: Only enable the test on EABI and
NaCl configurations.
* gas/arm/bl-local-v4t.d: Likewise.
* gas/arm/blx-local.d: Likewise.
* gas/arm/branch-reloc.d: Likewise.
ld/testsuite/ChangeLog:
2014-07-10 Will Newton <will.newton@linaro.org>
* ld-arm/arm-elf.exp (armelftests_nonacl): Move Cortex-A8 fix
tests, IFUNC tests and other EABI requiring tests to...
(armeabitests_nonacl): ...here.
* ld-arm/arm-app-abs32.d: Loosen regex for architecture type
to allow test to pass on configurations without an attributes
section.
* ld-arm/arm-app.d: Likewise.
* ld-arm/arm-lib-plt32.d: Likewise.
* ld-arm/arm-lib.d: Likewise.
* ld-arm/arm-static-app.d: Likewise.
* ld-arm/armthumb-lib.d: Likewise.
* ld-arm/cortex-a8-far.d: Likewise.
* ld-arm/farcall-mixed-app.d: Likewise.
* ld-arm/farcall-mixed-lib-v4t.d: Likewise.
* ld-arm/farcall-mixed-lib.d: Likewise.
* ld-arm/mixed-app-v5.d: Likewise.
* ld-arm/mixed-app.d: Likewise.
* ld-arm/mixed-lib.d: Likewise.
* ld-arm/tls-app.d: Likewise.
* ld-arm/tls-descrelax-be32.d: Likewise.
* ld-arm/tls-descrelax.d: Likewise.
* ld-arm/tls-descseq.d: Likewise.
* ld-arm/tls-gdesc-got.d: Likewise.
* ld-arm/tls-gdesc.d: Likewise.
* ld-arm/tls-gdierelax.d: Likewise.
* ld-arm/tls-gdierelax2.d: Likewise.
* ld-arm/tls-gdlerelax.d: Likewise.
* ld-arm/tls-lib-loc.d: Likewise.
* ld-arm/tls-lib.d: Likewise.
* ld-arm/tls-thumb1.d: Likewise.
Alan Modra <amodra@gmail.com>
bfd/
* elf32-arm.c (a8_erratum_fix): Add st_type field to record the
destination mode of the a8 stub.
(elf32_arm_link_hash_table): Add top_id field.
(elf32_arm_link_hash_table_create): Initialize top_id.
(arm_type_of_stub): Update prototype, st_type can now be updated
by this function. Actual destination address in case of PLT is
computed here, to help factorizing code.
(elf32_arm_stub_name): Update prototype, use stub_type additional
parameter to build stub name.
(elf32_arm_get_stub_entry): Update prototype, use stub_type
additional parameter to build stub entry.
(arm_build_one_stub): Use bfd_put_16/bfd_put_32 instead of
put_thumb_insn/put_arm_insn as BE8 encoding is now handled later.
Call elf32_arm_final_link_relocate to process all in-stub
relocations.
(elf32_arm_setup_section_lists): Update top_id.
(cortex_a8_erratum_scan): Record stub destination mode.
(elf32_arm_size_stubs): Update call to arm_type_of_stub according
to new prototype.
(elf32_arm_final_link_relocate): Enable processing of in-stub
REL32 relocations. Rely on arm_type_of_stub to detect if a stub is
needed, enabling code factorization.
(elf32_arm_final_link): Process stub sections.
(elf32_arm_output_map_sym): Add entry to code/data map.
ld/testsuite/
* ld-arm/arm-elf.exp: Change .text start address for
farcall-thumb-arm tests. Add v4t variant for farcall-mixed-lib
test.
* ld-arm/farcall-mixed-lib-v4t.d: New test.
* ld-arm/farcall-mixed-lib1.s: Don't force armv5t.
* ld-arm/farcall-mixed-lib2.s: Likewise.
* ld-arm/arm-call.d: Update expected results.
* ld-arm/cortex-a8-far.d: Likewise.
* ld-arm/farcall-group-size2.d: Likewise.
* ld-arm/farcall-group.d: Likewise.
* ld-arm/farcall-mix.d: Likewise.
* ld-arm/farcall-mix2.d: Likewise.
* ld-arm/farcall-mixed-app-v5.d: Likewise.
* ld-arm/farcall-mixed-app.d: Likewise.
* ld-arm/farcall-mixed-lib.d: Likewise.
* ld-arm/farcall-thumb-arm.d: Likewise.
* ld-arm/farcall-thumb-arm-blx.d: Likewise.
* ld-arm/farcall-thumb-arm-pic-veneer.d: Likewise.
* ld-arm/farcall-thumb-arm-blx-pic-veneer.d: Likewise.
* ld-arm/farcall-thumb-arm.s: Update test. Add a new call to
potentially generate different types of stubs.
* arm-dis.c (coprocessor): Print the LDC and STC versions of the
LFM and SFM instructions as comments,.
Improve consistency of formatting for instructions displayed as
comments and decimal values displayed with their hexadecimal
equivalents.
Formatting tidy ups.
Updated expected disassembler regexps.
* arm-dis.c (enum opcode_sentinels): New: Used to mark the
boundary between variaant and generic coprocessor instuctions.
(coprocessor): Use it.
Fix architecture version of MCRR and MRRC instructions.
(arm_opcdes): Fix patterns for STRB and STRH instructions.
(print_insn_coprocessor): Check architecture and extension masks.
Print a hexadecimal version of any decimal constant that is
outside of the range of -16 to +32.
(print_arm_address): Add a return value of the offset used in the
adress, if it is worth printing a hexadecimal version of it.
(print_insn_neon): Print a hexadecimal version of any decimal
constant that is outside of the range of -16 to +32.
(print_insn_arm): Likewise.
(print_insn_thumb16): Likewise.
(print_insn_thumb32): Likewise.
PR 10297
* arm-dis.c (UNDEFINED_INSTRUCTION): New macro for a description
of an undefined instruction.
(arm_opcodes): Use it.
(thumb_opcod): Use it.
(thumb32_opc): Use it.
Update expected disassembly regrexps in GAS and LD testsuites.
bfd/
* elf32-arm.c (elf32_arm_size_stubs): Use PLT address as
destination for defined dynamic symbols when deciding whether to
insert a stub or not.
(allocate_dynrelocs): Make sure functions are not marked as Thumb
when actually accessed through a PLT, even when generating a
shared lib.
ld/testsuite:
* ld-arm/farcall-mixed-app.s: Add new references to check more
modes switching.
* ld-arm/farcall-mixed-lib1.s: Likewise.
* ld-arm/farcall-mixed-app-v5.d: Update expected result.
* farcall-mixed-app.d: Likewise.
* ld-arm/farcall-mixed-lib.d: Likewise.
Alan Modra