normally RELA relocs in BFD should not consider the contents of the
relocated place. The aarch64 psABI is even stricter, it specifies
(section 5.7.16) that all RELA relocs _must_ be idempotent.
Since the inception of the aarch64 BFD backend all the relocs have a
non-zero src_mask, and hence break this invariant. It's normally not
a very visible problem as one can see it only when the relocated place
already contains a non-zero value, which usually only happens sometimes
when using 'ld -r' (or as in the testcase when jumping through hoops to
generate the relocations). Or with alternative toolchains that do encode
stuff in the relocated places with the assumption that a relocation
to that place ignores whatever is there (as they can according to
the psABI).
Golang is such a toolchain and https://github.com/golang/go/issues/39927
is ultimately caused by this problem: the testcase testGCData failing
is caused by the garbage collection data-structure to describe a type
containing pointers to be wrong. It's wrong because a field that's
supposed to contain a file-relative offset (to some gcbits) has a
relocation applied and that relocation has an addend which also is
already part of the go-produced object file (so the addend is
implicitely applied twice).
bfd/
PR ld/30437
* elfnn-aarch64.c (elfNN_aarch64_howto_table): Clear src_mask
if all relocation descriptors.
ld/
* testsuite/ld-aarch64/rela-idempotent.s: New testcase.
* testsuite/ld-aarch64/rela-idempotent.d: New.
* testsuite/ld-aarch64/aarch64-elf.exp: Run it.
While only a secondary issue there, the testcase of PR gas/27212 exposes
an oversight in relocation handling: Just like e.g. Arm32, which has a
similar comment and a similar check, relocations against STN_UNDEF have
to be permitted to satisfy the ELF spec.
Insert two stubs in a BTI enabled binary when fixing long calls: The
first is near the call site and uses an indirect jump like before,
but it targets the second stub that is near the call target site and
uses a direct jump.
This is needed when a single stub breaks BTI compatibility.
The stub layout is kept fixed between sizing and building the stubs,
so the location of the second stub is known at build time, this may
introduce padding between stubs when those are relaxed. Stub layout
with BTI disabled is unchanged.
We already use C99's __func__ in places, use it more generally. This
patch doesn't change uses in the testsuite. I've also left one in
gold.h that is protected by GCC_VERSION < 4003. If any of the
remaining uses bothers anyone I invite patches.
bfd/
* bfd-in.h: Replace __FUNCTION__ with __func__.
* elf32-bfin.c: Likewise.
* elfnn-aarch64.c: Likewise.
* elfxx-sparc.c: Likewise.
* bfd-in2.h: Regenerate.
gas/
* config/tc-cris.c: Replace __FUNCTION__ with __func__.
* config/tc-m68hc11.c: Likewise.
* config/tc-msp430.c: Likewise.
gold/
* dwp.h: Replace __FUNCTION__ with __func__.
* gold.h: Likewise, except for use inside GCC_VERSION < 4003.
ld/
* emultempl/pe.em: Replace __FUNCTION__ with __func__.
* emultempl/pep.em: Likewise.
* pe-dll.c: Likewise.
The newer update-copyright.py fixes file encoding too, removing cr/lf
on binutils/bfdtest2.c and ld/testsuite/ld-cygwin/exe-export.exp, and
embedded cr in binutils/testsuite/binutils-all/ar.exp string match.
The warning about discarded sections in elf_link_input_bfd doesn't
belong there since the code is dealing with symbols. Multiple symbols
in a discarded section will result in multiple identical warnings
about the section. Move the warning to a new function in ldlang.c.
The patch also tidies the warning quoting of section and file names,
consistently using `%pA' and `%pB'. I'm no stickler for one style of
section and file name quoting, but they ought to be consistent within
a warning, eg. see the first one fixed in ldlang.c, and when a warning
is emitted for multiple targets they all ought to use exactly the same
format string to reduce translation work. elf64-ppc.c loses the
build_one_stub errors since we won't get there before hitting the
fatal errors in size_one_stub.
bfd/
* elflink.c (elf_link_input_bfd): Don't warn here about
discarded sections.
* elf32-arm.c (arm_build_one_stub): Use consistent style in
--enable-non-contiguous-regions error.
* elf32-csky.c (csky_build_one_stub): Likewise.
* elf32-hppa.c (hppa_build_one_stub): Likewise.
* elf32-m68hc11.c (m68hc11_elf_build_one_stub): Likewise.
* elf32-m68hc12.c (m68hc12_elf_build_one_stub): Likewise.
* elf32-metag.c (metag_build_one_stub): Likewise.
* elf32-nios2.c (nios2_build_one_stub): Likewise.
* elfnn-aarch64.c (aarch64_build_one_stub): Likewise.
* xcofflink.c (xcoff_build_one_stub): Likewise.
* elf64-ppc.c (ppc_size_one_stub): Likewise.
(ppc_build_one_stub): Delete dead code.
ld/
* ldlang.c (lang_add_section): Use consistent style in
--enable-non-contiguous-regions warnings.
(size_input_section): Likewise.
(warn_non_contiguous_discards): New function.
(lang_process): Call it.
* testsuite/ld-arm/non-contiguous-arm.d: Update.
* testsuite/ld-arm/non-contiguous-arm4.d: Update.
* testsuite/ld-arm/non-contiguous-arm7.d: Add
--enable-non-contiguous-regions-warnings.
* testsuite/ld-arm/non-contiguous-arm7.err: New.
* testsuite/ld-powerpc/non-contiguous-powerpc.d: Update.
* testsuite/ld-powerpc/non-contiguous-powerpc64.d: Update.
Always call elf_backend_output_arch_local_syms since only the backend
knows if elf_backend_output_arch_local_syms is needed when all symbols
are striped. elf_backend_output_arch_local_syms is defined only for
x86, ARM and AARCH64. On x86, elf_backend_output_arch_local_syms must
be called to handle local IFUNC symbols even if all symbols are striped.
Update ARM and AARCH64 to skip elf_backend_output_arch_local_syms when
symbols aren't needed.
bfd/
PR ld/29797
* elf32-arm.c (elf32_arm_output_arch_local_syms): Skip if symbols
aren't needed.
* elfnn-aarch64.c (elfNN_aarch64_output_arch_local_syms):
Likewise.
* elflink.c (bfd_elf_final_link): Always call
elf_backend_output_arch_local_syms if available.
ld/
PR ld/29797
* testsuite/ld-elf/linux-x86.exp: Run PR ld/29797 test.
* testsuite/ld-elf/pr29797.c: New file.
BFD_VMA_FMT can't be used in format strings that need to be
translated, because the translation won't work when the type of
bfd_vma differs from the machine used to compile .pot files. We've
known about this for a long time, but patches slip through review.
So just get rid of BFD_VMA_FMT, instead using the appropriate PRId64,
PRIu64, PRIx64 or PRIo64 and SCN variants for scanf. The patch is
mostly mechanical, the only thing requiring any thought is casts
needed to preserve PRId64 output from bfd_vma values, or to preserve
one of the unsigned output formats from bfd_signed_vma values.
In aarch64_tls_transition_without_check and elfNN_aarch64_tls_relax we
choose whether to perform a relaxation to an IE access model or an LE
access model based on whether the symbol itself is marked as local (i.e.
`h == NULL`).
This is problematic in two ways. The first is that sometimes a global
dynamic access can be relaxed to an initial exec access when creating a
shared library, and if that happens on a local symbol then we currently
relax it to a local exec access instead. This usually does not happen
since we only relax an access if aarch64_can_relax_tls returns true and
aarch64_can_relax_tls does not have the same problem. However, it can
happen when we have seen both an IE and GD access on the same symbol.
This case is exercised in the newly added testcase tls-relax-gd-ie-2.
The second problem is that deciding based on whether the symbol is local
misses the case when the symbol is global but is still non-interposable
and known to be located in the executable. This happens on all global
symbols in executables.
This case is exercised in the newly added testcase tls-relax-ie-le-4.
Here we adjust the condition we base our relaxation on so that we relax
to local-exec if we are creating an executable and the relevant symbol
we're accessing is stored inside that executable.
-- Updating tests for new relaxation criteria
Many of the tests added to check our relaxation to IE were implemented
by taking advantage of the fact that we did not relax a global symbol
defined in an executable.
Since a global symbol defined in an executable is still not
interposable, we know that a TLS version of such a symbol will be in the
main TLS block. This means that we can perform a stronger relaxation on
such symbols and relax their accesses to a local-exec access.
Hence we have to update all tests that relied on the older suboptimal
decision making.
The two cases when we still would want to relax a general dynamic access
to an initial exec one are:
1) When in a shared library and accessing a symbol which we have already
seen accessed with an initial exec access sequence.
2) When in an executable and accessing a symbol defined in a shared
library.
Both of these require shared library support, which means that these
tests are now only available on targets with that.
I have chosen to switch the existing testcases from a plain executable
to one dynamically linked to a shared object as that doesn't require
changing the testcases quite so much (just requires accessing a
different variable rather than requiring adding another code sequence).
The tls-relax-all testcase was an outlier to the above approach, since
it included a general dynamic access to both a local and global symbol
and inspected for the difference accordingly.
The Linux kernel can dump memory tag segments to a core file, one segment
per mapped range. The format and documentation can be found in the Linux
kernel tree [1].
The following patch adjusts bfd and binutils so they can handle this new
segment type and display it accordingly. It also adds code required so GDB
can properly read/dump core file data containing memory tags.
Upon reading, each segment that contains memory tags gets mapped to a
section named "memtag". These sections will be used by GDB to lookup the tag
data. There can be multiple such sections with the same name, and they are not
numbered to simplify GDB's handling and lookup.
There is another patch for GDB that enables both reading
and dumping of memory tag segments.
Tested on aarch64-linux Ubuntu 20.04.
[1] Documentation/arm64/memory-tagging-extension.rst (Core Dump Support)
__attribute__((visibility("protected"))) void *foo() {
return (void *)foo;
}
gcc -fpic -shared -fuse-ld=bfd fails with the confusing diagnostic:
relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `foo' which may bind externally can not be used when making a shared object; recompile with -fPIC
Call _bfd_elf_symbol_refs_local_p with local_protected==true to suppress
the error. The new behavior matches gold and ld.lld.
Note: if some code tries to use direct access relocations to take the
address of foo (likely due to -fno-pic), the pointer equality will
break, but the error should be reported on the executable link, not on
the innocent shared object link. glibc 2.36 will give a warning at
relocation resolving time.
Follow-up to commit 90b7a5df15
("aarch64: Disallow copy relocations on protected data").
Commit 32f573bcb3 changed ld to produce
R_AARCH64_GLOB_DAT but that defeated the purpose of protected visibility
as an optimization. Restore the previous behavior (which matches
ld.lld) by defining elf_backend_extern_protected_data to 0.
If an executable has copy relocations for extern protected data, that
can only work if the shared object containing the definition is built
with assumptions (a) the compiler emits GOT-generating relocations (b)
the linker produces R_*_GLOB_DAT instead of R_*_RELATIVE. Otherwise the
shared object uses its own definition directly and the executable
accesses a stale copy. Note: the GOT relocations defeat the purpose of
protected visibility as an optimization, and it turns out this never
worked perfectly.
glibc 2.36 will warn on copy relocations on protected data. Let's
produce a warning at link time, matching ld.lld which has been used on
many aarch64 OSes.
Note: x86 requires GNU_PROPERTY_NO_COPY_ON_PROTECTED to have the error.
This is to largely due to GCC 5's "x86-64: Optimize access to globals in
PIE with copy reloc" which started to use direct access relocations for
external data symbols in -fpie mode.
GCC's aarch64 port does not have the change. Nowadays with most builds
switching to -fpie/-fpic, aarch64 mostly doesn't need to worry about
copy relocations. So for aarch64 we simply don't check
GNU_PROPERTY_NO_COPY_ON_PROTECTED.
The result of running etc/update-copyright.py --this-year, fixing all
the files whose mode is changed by the script, plus a build with
--enable-maintainer-mode --enable-cgen-maint=yes, then checking
out */po/*.pot which we don't update frequently.
The copy of cgen was with commit d1dd5fcc38ead reverted as that commit
breaks building of bfp opcodes files.
The idea of this patch is to make it easy to see which targets (just
sparc) have ELF_MINPAGESIZE != ELF_COMMONPAGESIZE.
* elf32-arm.c (ELF_MINPAGESIZE): Don't define.
* elf32-metag.c: Likewise.
* elfnn-aarch64.c: Likewise.
* elf64-x86-64.c: Likewise. Also don't redefine a bunch of other
macros for l1om elf64-target.h use that are unchanged from default.
We can't assume .dynamic is a multiple of ElfNN_External_Dyn, at least
not when presented with fuzzed object files.
* elfnn-aarch64.c (get_plt_type): Don't access past end of
improperly sized .dynamic.
bfd * elf.c (_bfd_elf_maybe_function_sym): Do not accept annobin
symbols as potential function symbols.
* elfnn-aarch64.c (elfNN_aarch64_maybe_function_sym): Likewise.
* elf64-ppc.c (ppc64_elf_maybe_function_sym): Likewise.
* elf32-arm.c (elf32_arm_maybe_function_sym): Likewise.
ld * testsuite/ld-elf/anno-sym.s: New test source file.
* testsuite/ld-elf/anno-sym.d: New test driver.
* testsuite/ld-elf/anno-sym.l: New test error output.
* elf32-arm.c (elf32_arm_print_private_bfd_data): Prefix hex value
of private flags with 0x.
* elfnn-aarch64.c (elfNN_aarch64_print_private_bfd_data): Likewise.
The fix in 7e05773767 introduced a PLT
for conditional jumps when the target symbol is undefined. This is
incorrect because conditional branch relocations are not allowed to
clobber IP0/IP1 and hence, should not result in a dynamic relocation.
Revert that change and in its place, issue an error when the target
symbol is undefined.
bfd/
2020-09-10 Siddhesh Poyarekar <siddesh.poyarekar@arm.com>
* elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Revert
changes in 7e05773767. Set
error for undefined symbol in BFD_RELOC_AARCH64_BRANCH19 and
BFD_RELOC_AARCH64_TSTBR14 relocations.
ld/
2020-09-10 Siddhesh Poyarekar <siddesh.poyarekar@arm.com>
* testsuite/ld-aarch64/emit-relocs-560.d: Expect error instead
of valid output.
bfd * elfnn-aarch64.c (_bfd_aarch64_erratum_835769_scan): Only sort
the data map if there are entries in it.
(_bfd_aarch64_erratum_843419_scan): Likewise.
opcodes * aarch64-dis.c (get_sym_code_type): Return FALSE for non-ELF
symbols.
On aarch64 the first PLT entry is 32 bytes, subsequent entries
are 16 bytes by default but can be 24 bytes with BTI or with
PAC-PLT.
sh_entsize of .plt was set to the PLT entry size, so in some
cases sh_size % sh_entsize != 0, which breaks some tools.
Note that PLT0 (and the TLSDESC stub code which is also in the
PLT) were historically not padded up to meet the sh_size
requirement, but to ensure that PLT stub code is aligned on
cache lines. Similar layout is present on other targets too
which just happens to make sh_size a multiple of sh_entsize and
it is not expected that sh_entsize of .plt is used for anything.
This patch sets sh_entsize of .plt to 0: the section does not
hold a table of fixed-size entries so other values are not
conforming in principle to the ELF spec.
bfd/ChangeLog:
PR ld/26312
* elfnn-aarch64.c (elfNN_aarch64_init_small_plt0_entry): Set sh_entsize
to 0.
(elfNN_aarch64_finish_dynamic_sections): Remove sh_entsize setting.
Add ifunc_resolvers to elf_link_hash_table and use it for both x86 and
ppc64. Before glibc commit b5c45e837, DT_TEXTREL is incompatible with
IFUNC resolvers. Set ifunc_resolvers if there are IFUNC resolvers and
issue a warning for IFUNC resolvers with DT_TEXTREL.
bfd/
PR ld/18801
* elf-bfd.h (elf_link_hash_table): Add ifunc_resolvers.
(_bfd_elf_allocate_ifunc_dyn_relocs): Remove the
bfd_boolean * argument. Set ifunc_resolvers if there are IFUNC
resolvers.
* elf-ifunc.c (_bfd_elf_allocate_ifunc_dyn_relocs): Updated.
Set ifunc_resolvers if there are FUNC resolvers.
* elf64-ppc.c (ppc_link_hash_table): Remove local_ifunc_resolver.
(build_global_entry_stubs_and_plt): Replace local_ifunc_resolver
with elf.ifunc_resolvers.
(write_plt_relocs_for_local_syms): Likewise.
(ppc64_elf_relocate_section): Likewise.
(ppc64_elf_finish_dynamic_sections): Likewise.
* elfnn-aarch64.c (elfNN_aarch64_allocate_ifunc_dynrelocs):
Updated.
* elfxx-x86.c (elf_x86_allocate_dynrelocs): Likewise.
(_bfd_x86_elf_size_dynamic_sections): Check elf.ifunc_resolvers
instead of readonly_dynrelocs_against_ifunc.
* elfxx-x86.h (elf_x86_link_hash_table): Remove
readonly_dynrelocs_against_ifunc.
ld/
PR ld/18801
* testsuite/ld-i386/i386.exp: Run ifunc-textrel-1a,
ifunc-textrel-1b, ifunc-textrel-2a and ifunc-textrel-2b.
* testsuite/ld-x86-64/x86-64.exp: Likewise.
* testsuite/ld-i386/ifunc-textrel-1a.d: Likewise.
* testsuite/ld-i386/ifunc-textrel-1b.d: Likewise.
* testsuite/ld-i386/ifunc-textrel-2a.d: Likewise.
* testsuite/ld-i386/ifunc-textrel-2b.d: Likewise.
* testsuite/ld-x86-64/ifunc-textrel-1.s: Likewise.
* testsuite/ld-x86-64/ifunc-textrel-1a.d: Likewise.
* testsuite/ld-x86-64/ifunc-textrel-1b.d: Likewise.
* testsuite/ld-x86-64/ifunc-textrel-2.s: Likewise.
* testsuite/ld-x86-64/ifunc-textrel-2a.d: Likewise.
* testsuite/ld-x86-64/ifunc-textrel-2b.d: Likewise.
* testsuite/ld-i386/pr18801a.d: Expect warning for IFUNC
resolvers.
* testsuite/ld-i386/pr18801b.d: Likewise.
* estsuite/ld-x86-64/pr18801a.d: Likewise.
* estsuite/ld-x86-64/pr18801b.d: Likewise.
All ELF backends with TLS descriptor support have
/* The offset into splt of the PLT entry for the TLS descriptor
resolver. Special values are 0, if not necessary (or not found
to be necessary yet), and -1 if needed but not determined
yet. */
bfd_vma tlsdesc_plt;
/* The GOT offset for the lazy trampoline. Communicated to the
loader via DT_TLSDESC_GOT. The magic value (bfd_vma) -1
indicates an offset is not allocated. */
bfd_vma tlsdesc_got;
in symbol hash entry. Move tlsdesc_plt/tlsdesc_got to elf_link_hash_entry
to reduce code duplication.
* elf-bfd.h (elf_link_hash_entry): Add tlsdesc_plt and
tlsdesc_got.
* elf32-arm.c (elf32_arm_link_hash_table): Remove tlsdesc_plt
and dt_tlsdesc_got.
(elf32_arm_size_dynamic_sections): Updated. Clear
root.tlsdesc_plt for DF_BIND_NOW.
(elf32_arm_finish_dynamic_sections): Updated.
(elf32_arm_output_arch_local_syms): Likewise.
* elf32-nds32.c (nds32_elf_size_dynamic_sections): Updated.
Clear root.tlsdesc_plt for DF_BIND_NOW.
(nds32_elf_finish_dynamic_sections): Updated.
* elf32-nds32.h (elf_nds32_link_hash_table): Remove
dt_tlsdesc_plt and dt_tlsdesc_got.
* elf64-x86-64.c (elf_x86_64_finish_dynamic_sections): Updated.
* elfnn-aarch64.c (elf_aarch64_link_hash_table): Remove
tlsdesc_plt and dt_tlsdesc_got.
(elfNN_aarch64_allocate_dynrelocs): Updated.
(elfNN_aarch64_finish_dynamic_sections): Likewise.
(elfNN_aarch64_size_dynamic_sections): Updated. Clear
root.tlsdesc_plt for DF_BIND_NOW. Don't check DF_BIND_NOW
twice.
* elfxx-x86.c (elf_x86_allocate_dynrelocs): Updated.
(_bfd_x86_elf_size_dynamic_sections): Likewise.
(_bfd_x86_elf_finish_dynamic_sections): Likewise.
* elfxx-x86.h (elf_x86_link_hash_table): Remove tlsdesc_plt and
tlsdesc_got.
The linker silently writes out a conditional branch to 0 if the
target symbol in R_AARCH64_CONDBR19 or R_AARCH64_TSTBR14 relocations is
undefined. Emit a PLT instead so that behaviour is the same for these
relocations as the llvm linker.
The special behaviour for undefined weak symbols, where conditional
branches to such symbols result in a branch unto themselves, has been
retained. This is because the weak-undefined.s test explicitly checks
for that, leading me to conclude that it's expected behaviour.
bfd * elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Club
BFD_RELOC_AARCH64_BRANCH19 and BFD_RELOC_AARCH64_TSTBR14
cases with BFD_RELOC_AARCH64_JUMP26.
(elfNN_aarch64_check_relocs): Likewise.
ld * testsuite/ld-aarch64/aarch64-elf.exp: New test
emit-relocs-560.
* testsuite/ld-aarch64/emit-relocs-560.d: New file.
* testsuite/ld-aarch64/emit-relocs-560.s: New file.
PR ld/25665
* bfd/elfnn-aarch64.c (group_sections): Copy implementation
from elf32-arm.c.
* testsuite/ld-aarch64/aarch64-elf.exp: Add new test.
* testsuite/ld-aarch64/farcall-group.s: New large group test.
* testsuite/ld-aarch64/farcall-group.d: Likewise.
