If you should somehow link non-pic objects into a PIE or shared
library, resulting in an object with DT_TEXTREL (text relocations)
set, and your executable or shared library also contains GNU indirect
functions, then you're in trouble. To apply dynamic relocations
ld.so will make the text segment writable. On most systems this will
make the text segment non-executable, which will then result in a
segfault when ld.so tries to run ifunc resolvers when applying
relocations against ifuncs.
This patch teaches PowerPC ld to detect the situation, and warn.
* elf64-ppc.c (struct ppc_link_hash_table): Add
local_ifunc_resolver and maybe_local_ifunc_resolver.
(ppc_build_one_stub): Set flags on emitting dynamic
relocation to ifunc.
(ppc64_elf_relocate_section): Likewise.
(ppc64_elf_finish_dynamic_symbol): Likewise.
(ppc64_elf_finish_dynamic_sections): Error on DT_TEXTREL with
local dynamic relocs to ifuncs.
* elf32-ppc.c (struct ppc_elf_link_hash_table): Add
local_ifunc_resolver and maybe_local_ifunc_resolver.
(ppc_elf_relocate_section): Set flag on emitting dynamic
relocation to ifuncs.
(ppc_elf_finish_dynamic_symbol): Likewise.
(ppc_elf_finish_dynamic_sections): Error on DT_TEXTREL with local
dynamic relocs to ifuncs.
ppc64_elf_relocate_section lacked a check which meant that it emitted
dynamic relocs against a hidden undefweak symbol for which no dynamic
relocs had been allocated.
PR 21224
PR 20519
* elf64-ppc.c (ppc64_elf_relocate_section): Add missing
dyn_relocs check.
In the last patch I said "The patch also fixes overflow checking".
In fact, there wasn't anything wrong with the previous code. So,
revert that change. The new checks are OK too, so this is just a
tidy.
* elf64-ppc.c (ppc64_elf_ha_reloc): Revert last change.
(ppc64_elf_relocate_section): Likewise.
A number of places in elf32-nios.c created dynamic sections but didn't
set the hash table dynobj. That meant we could have duplicate dynamic
sections connected to a number of bfds, so size_dynamic_sections
didn't properly discard or allocate contents.
Also, the entire set of dynamic sections was created in check_relocs
on seeing GOT relocs, when only .got related sections are needed,
probably done to hide segfaults later in finish_dynamic_sections.
The patch fixes these issues and makes the assembler emit errors when
nios2 lacks the necessary pc-relative relocs for subtraction
expressions, rather than silently generating bad code.
eg. ld-elf/merge. I've also tidied uses of elf32_nios2_hash_table and
elf_hash_table.
bfd/
PR 20995
* elf32-nios2.c (nios2_elf32_relocate_section): Use htab
rather than elf32_nios2_hash_table or elf_hash_table.
(create_got_section): Likewise.
(nios2_elf32_finish_dynamic_symbol): Likewise.
(nios2_elf32_adjust_dynamic_symbol): Likewise.
(nios2_elf32_size_dynamic_sections): Likewise.
(nios2_elf32_check_relocs): Delete dynobj, sgot, and srelgot
vars. Use htab equivalents directly instead. Don't create
all dynamic sections on needing just the GOT. Use a goto
rather than a fall-through with reloc test. Ensure
htab->dynobj is set when making dynamic sreloc section.
(nios2_elf32_finish_dynamic_sections): Delete dynobj, use htab
equivalent directly instead. Don't segfault on looking for
.dynamic when dynamic sections have not been created. Don't
segfault on .got.plt being discarded.
(nios2_elf32_size_dynamic_sections): Delete plt and got vars.
Don't set "relocs" on .rela.plt. Do handle .sbss. Delete
fixme and another not so relevant comment.
(nios2_elf_add_symbol_hook): Delete dynobj var. If not
already set, set hash table dynobj on creating .sbss.
gas/
* config/tc-nios2.h (TC_FORCE_RELOCATION_SUB_LOCAL): Define.
ld/
* testsuite/ld-elf/merge.d: xfail for nios.
This came up because I was looking at ld/tmpdir/addpcis.o and noticed
the odd addends on REL16DX_HA. They ought to both be -4. The error
crept in due REL16DX_HA howto being pc-relative (as indeed it should
be), and code at gas/write.c:1001 after this comment
/* Make it pc-relative. If the back-end code has not
selected a pc-relative reloc, cancel the adjustment
we do later on all pc-relative relocs. */
*not* cancelling the pc-relative adjustment. So I've made a dummy
non-relative split reloc so that the generic code handles this, rather
than attempting to add hacks later in md_apply_fix which would not be
very robust. Having the new internal reloc also makes it easy to
support
addpcis rx,sym@ha
as an equivalent to
addpcis rx,(sym-0f)@ha
0:
The patch also fixes overflow checking, which must test whether the
addi will overflow too since @l relocs don't have any overflow check.
Lastly, since I was poking at md_apply_fix, I arranged to have the
generic gas/write.c code emit errors for subtraction expressions where
we lack reloc support.
include/
* elf/ppc64.h (R_PPC64_16DX_HA): New. Expand fake reloc comment.
* elf/ppc.h (R_PPC_16DX_HA): Likewise.
bfd/
* reloc.c (BFD_RELOC_PPC_16DX_HA): New.
* elf64-ppc.c (ppc64_elf_howto_raw <R_PPC64_16DX_HA>): New howto.
(ppc64_elf_reloc_type_lookup): Translate new bfd reloc.
(ppc64_elf_ha_reloc): Correct overflow test on REL16DX_HA.
(ppc64_elf_relocate_section): Likewise.
* elf32-ppc.c (ppc_elf_howto_raw <R_PPC_16DX_HA>): New howto.
(ppc_elf_reloc_type_lookup): Translate new bfd reloc.
(ppc_elf_check_relocs): Handle R_PPC_16DX_HA to pacify gcc.
* libbfd.h: Regenerate.
* bfd-in2.h: Regenerate.
gas/
* config/tc-ppc.c (md_assemble): Use BFD_RELOC_PPC_16DX_HA for addpcis.
(md_apply_fix): Remove fx_subsy check. Move code converting to
pcrel reloc earlier and handle BFD_RELOC_PPC_16DX_HA. Remove code
emiiting errors on seeing fx_pcrel set on unexpected relocs, as
that is done now by the generic code via..
* config/tc-ppc.h (TC_FORCE_RELOCATION_SUB_LOCAL): ..this. Define.
(TC_VALIDATE_FIX_SUB): Define.
ld/
* testsuite/ld-powerpc/addpcis.d: Define ext1 and ext2 at
limits of addpcis range.
I'd made this dynamic section read-only so a flag test distinguished
it from .dynbss, but like any other .data.rel.ro section it really
should be marked read-write. (It is read-only after relocation, not
before.) When using the standard linker scripts this usually doesn't
matter since the output section is among other read-write sections and
not page aligned. However, it might matter in the extraordinary case
of the dynamic section being the only .data.rel.ro section with the
output section just happening to be page aligned and a multiple of a
page in size. In that case the output section would be read-only, and
live it its own read-only PT_LOAD segment, which is incorrect.
* elflink.c (_bfd_elf_create_dynamic_sections): Don't make
dynamic .data.rel.ro read-only.
* elf32-arm.c (elf32_arm_finish_dynamic_symbol): Compare section
rather than section flags when deciding where copy reloc goes.
* elf32-cris.c (elf_cris_finish_dynamic_symbol): Likewise.
* elf32-hppa.c (elf32_hppa_finish_dynamic_symbol): Likewise.
* elf32-i386.c (elf_i386_finish_dynamic_symbol): Likewise.
* elf32-metag.c (elf_metag_finish_dynamic_symbol): Likewise.
* elf32-microblaze.c (microblaze_elf_finish_dynamic_symbol): Likewise.
* elf32-nios2.c (nios2_elf32_finish_dynamic_symbol): Likewise.
* elf32-or1k.c (or1k_elf_finish_dynamic_symbol): Likewise.
* elf32-ppc.c (ppc_elf_finish_dynamic_symbol): Likewise.
* elf32-s390.c (elf_s390_finish_dynamic_symbol): Likewise.
* elf32-tic6x.c (elf32_tic6x_finish_dynamic_symbol): Likewise.
* elf32-tilepro.c (tilepro_elf_finish_dynamic_symbol): Likewise.
* elf64-ppc.c (ppc64_elf_finish_dynamic_symbol): Likewise.
* elf64-s390.c (elf_s390_finish_dynamic_symbol): Likewise.
* elf64-x86-64.c (elf_x86_64_finish_dynamic_symbol): Likewise.
* elfnn-aarch64.c (elfNN_aarch64_finish_dynamic_symbol): Likewise.
* elfnn-riscv.c (riscv_elf_finish_dynamic_symbol): Likewise.
* elfxx-mips.c (_bfd_mips_vxworks_finish_dynamic_symbol): Likewise.
* elfxx-sparc.c (_bfd_sparc_elf_finish_dynamic_symbol): Likewise.
* elfxx-tilegx.c (tilegx_elf_finish_dynamic_symbol): Likewise.
Interpret the `jalr $0, $25' instruction encoding with an R_MIPS_JALR
relocation attached as an alias to `jr $25' and convert the jump to an
equivalent branch where possible, consequently covering the MIPSr6
architecture for the purpose of this optimization too.
bfd/
* elfxx-mips.c (mips_elf_perform_relocation): Also handle the
`jalr $0, $25' instruction encoding.
gas/
* testsuite/gas/mips/jalr4.s: Add `jalr $0, $25' instructions.
* testsuite/gas/mips/jalr4.d: Adjust accordingly. Remove MIPSr6
encoding patterns.
* testsuite/gas/mips/jalr4-n64.d: Likewise.
* testsuite/gas/mips/mipsr6@jalr4.d: New test.
* testsuite/gas/mips/mipsr6@jalr4-n32.d: New test.
* testsuite/gas/mips/mipsr6@jalr4-n64.d: New test.
ld/
* testsuite/ld-mips-elf/jalr4.dd: Adjust for `jalr $0, $25'
instructions.
* testsuite/ld-mips-elf/jalr4-r6.dd: New test.
* testsuite/ld-mips-elf/mips-elf.exp: Run the new test.
PR ld/21180
* elf32-microblaze.c (microblaze_elf_finish_dynamic_symbol): Avoid
generating a seg-fault when encountering a symbol that has been
deleted by garbage collection.
This patch fixes a number of issues in the ARC backend.
- The ARC size_dynamic_sections was trashing dynamic section contents,
in particular the .gnu.version_d contents. Those versions
definitions are therefore lost so they do not drain from the strtab,
resulting in assertion failures.
- The code attempting to set DT_TEXTREL was completely bogus.
- The ARC finish_dynamic_sections would segfault on trying to set
sh_entsize for .rela.plt if that section had been discarded.
- arc_create_dynamic_sections wouldn't have ever created dynamics
sections, which was just as well since the places it was called were
way too late to create dynamic sections. Its usefulness then
devolved down to finding just one dynamic section. All the others
packaged into a struct were unused.
- .interp wasn't set for PIEs.
* elf32-arc.c (struct dynamic_sections): Delete.
(enum dyn_section_types): Delete.
(dyn_section_names): Delete.
(arc_create_dynamic_sections): Delete.
(elf_arc_finish_dynamic_sections): Don't call the above. Don't
segfault on discarded .rela.plt section.
(elf_arc_size_dynamic_sections): Formatting. Don't call
arc_create_dynamic_sections. Don't allocate memory for sections
handled by the generic linker. Correct code finding relocs in
read-only sections. Set SEC_EXCLUDE on zero size .got,
.got.plt, and .dynbss sections. Do set .interp for pies.
bfd/ChangeLog:
2017-02-24 Andrew Waterman <andrew@sifive.com>
* elfnn-riscv.c (GP_NAME): New macro.
(riscv_global_pointer_value): Use it.
(_bfd_riscv_relax_lui): If symbol and global pointer are in same
output section, consider only that section's alignment.
Remove separate original NewABI JALR relocation handling, introduced
with commit d06471104a ("relax jalr $t9 [R_MIPS_JALR symbol] to bal
symbol"), <https://sourceware.org/ml/binutils/2003-03/msg00394.html>,
and only used by LD with the `--relax' option specified, and rely solely
on `mips_elf_perform_relocation' code, which has been introduced with
commit 1367d393bb ("On the RM9000 convert jal to bal if in range"),
<https://www.sourceware.org/ml/binutils/2004-12/msg00088.html> and since
made more complete, across all the three ABIs.
Also remove the `--relax' option, now irrelevant, from the tests added
with the former commit.
bfd/
* elfxx-mips.h (_bfd_mips_relax_section): Remove prototype.
* elfxx-mips.c (_bfd_mips_relax_section): Remove function.
* elf64-mips.c (bfd_elf64_bfd_relax_section): Remove macro.
* elfn32-mips.c (bfd_elf32_bfd_relax_section): Likewise.
ld/
* testsuite/ld-mips-elf/relax-jalr-n32.d: Remove `--relax'
option.
* testsuite/ld-mips-elf/relax-jalr-n32-shared.d: Likewise.
* testsuite/ld-mips-elf/relax-jalr-n64.d: Likewise.
* testsuite/ld-mips-elf/relax-jalr-n64-shared.d: Likewise.
Discard R_MIPS_JALR and R_MICROMIPS_JALR relocations associated with
jumps that cannot be converted to an equivalent branch right away in
`mips_elf_calculate_relocation' rather than letting them through to
`mips_elf_perform_relocation'. This includes cross-mode jumps which
need to flip the ISA bit or jumps to a misaligned location that cannot
be encoded with a branch, in addition to preemptible symbol references
already handled.
Cross-mode jumps are actually already rejected as the conversion is made
in `mips_elf_perform_relocation', so in this case this change only saves
some processing. Jumps to a misaligned location are however converted,
with bits causing misalignment lost, making resulting code functionally
different even if the lone effect is avoiding an address error exception
with an instruction fetch at the jump destination requested.
Add test cases suitable, also including GAS verification to confirm that
the JALR relocations explicitly requested have indeed been output in the
intermediate objects used.
bfd/
* elfxx-mips.c (mips_elf_calculate_relocation) <R_MIPS_JALR>
<R_MICROMIPS_JALR>: Discard relocation if `cross_mode_jump_p'
or misaligned.
gas/
* testsuite/gas/mips/jalr4.d: New test.
* testsuite/gas/mips/jalr4-n32.d: New test.
* testsuite/gas/mips/jalr4-n64.d: New test.
* testsuite/gas/mips/jalr4.s: New test source.
* testsuite/gas/mips/mips.exp: Run the new tests.
ld/
* testsuite/ld-mips-elf/jalr4.dd: New test.
* testsuite/ld-mips-elf/mips-elf.exp: Run the new test.
PR 20744
bfd/
* elf32-ppc.c (ppc_elf_howto_raw): Correct dst_mask on all VLE
16D relocations.
(ppc_elf_vle_split16): Correct field mask and shift for 16D relocs.
(ppc_elf_relocate_section): Correct calculation for VLE SDAREL
relocs.
ld/
* testsuite/ld-powerpc/vle-reloc-2.s: Use r6 for last insn of
each group.
* testsuite/ld-powerpc/vle-reloc-2.d: Update for above change
and sdarel reloc fix.
Complement commit b531344c34 ("PR ld/20828: Reorder the symbol sweep
stage of section GC") and commit 81ff47b3a5 ("PR ld/20828: Fix linker
script symbols wrongly forced local with section GC") and move symbol
version processing ahead of the symbol sweep stage of section GC, all in
`bfd_elf_size_dynamic_sections', so that version symbols created stay in
the global scope and are not output as local symbols to the dynamic
symbol table in the presence of corresponding symbol definitions pulled
from a DSO involved in a link.
Consolidate the whole of symbol version processing into a single block
from all parts scattered across the function and rearranging the local
variables used as necessary, however leaving the setting of dynamic
entries associated with the DT_VERDEF, DT_VERDEFNUM, DT_VERNEED and
DT_VERNEEDNUM tags and the SEC_EXCLUDE flag for unused `.gnu.version'
section in the original places.
With the rearrangement of code blocks `Elf_Internal_Verneed *t' would
shadow the previous definition of `struct bfd_elf_version_tree *t', so
rename the former variable to `vn'.
bfd/
PR ld/20828
* elflink.c (bfd_elf_size_dynamic_sections): Move symbol version
processing ahead of the call to `elf_gc_sweep_symbol'.
ld/
PR ld/20828
* testsuite/ld-elf/pr20828-d.sd: New test.
* testsuite/ld-elf/pr20828-e.sd: New test.
* testsuite/ld-elf/pr20828-v.od: New test.
* testsuite/ld-elf/pr20828-v.ver: New test version script.
* testsuite/ld-elf/pr20828-v.ld: New test linker script.
* testsuite/ld-elf/pr20828.ld: Add `.gnu.version' and
`.gnu.version_d'.
* testsuite/ld-elf/shared.exp: Run the new tests.
GDB Administrator
Alan Modra
Nick Clifton
Sam Thursfield
Maciej W. Rozycki
Andrew Waterman