This works like /include, but is not fatal if the requested symbol
wasn't found. This allows implementing the GNU ld option -u.
Differential Revision: https://reviews.llvm.org/D62976
llvm-svn: 362881
I've change the variable names used in PPC64.cpp from "Instr" to "Insn"
because "Insn" is a more common abbreviation for "instruction".
While changing PPC64.cpp relocateOne(), make R_PPC64_ADDR16_LO{_DS}
slightly more efficient by saving a read and a write for the TocOptimize
case.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D63043
llvm-svn: 362867
Summary:
When handling exports from the command line or from .def files, the
linker does a "fuzzy" string lookup to allow finding mangled symbols.
However, when the symbol is re-exported under a new name, the linker has
to transfer the decorations from the exported symbol over to the new
name. This is implemented by taking the mangled symbol that was found in
the object and replacing the original symbol name with the export name.
Before this patch, LLD implemented the fuzzy search by adding an
undefined symbol with the unmangled name, and then during symbol
resolution, checking if similar mangled symbols had been added after the
last round of symbol resolution. If so, LLD makes the original symbol a
weak alias of the mangled symbol. Later, to get the original symbol
name, LLD would look through the weak alias and forward it on to the
import library writer, which copies the symbol decorations. This
approach doesn't work when bar is itself a weak alias, as is the case in
asan. It's especially bad when the aliasee of bar contains the string
"bar", consider "bar_default". In this case, we would end up exporting
the symbol "foo_default" when we should've exported just "foo".
To fix this, don't look through weak aliases to find the mangled name.
Save the mangled name earlier during fuzzy symbol lookup.
Fixes PR42074
Reviewers: mstorsjo, ruiu
Subscribers: thakis, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62984
llvm-svn: 362849
We create several types of synthetic sections for loadable partitions, including:
- The dynamic symbol table. This allows code outside of the loadable partitions
to find entry points with dlsym.
- Creating a dynamic symbol table also requires the creation of several other
synthetic sections for the partition, such as the dynamic table and hash table
sections.
- The partition's ELF header is represented as a synthetic section in the
combined output file, and will be used by llvm-objcopy to extract partitions.
Differential Revision: https://reviews.llvm.org/D62350
llvm-svn: 362819
Branch Target Identification (BTI) and Pointer Authentication (PAC) are
architecture features introduced in v8.5a and 8.3a respectively. The new
instructions have been added in the hint space so that binaries take
advantage of support where it exists yet still run on older hardware. The
impact of each feature is:
BTI: For executable pages that have been guarded, all indirect branches
must have a destination that is a BTI instruction of the appropriate type.
For the static linker, this means that PLT entries must have a "BTI c" as
the first instruction in the sequence. BTI is an all or nothing
property for a link unit, any indirect branch not landing on a valid
destination will cause a Branch Target Exception.
PAC: The dynamic loader encodes with PACIA the address of the destination
that the PLT entry will load from the .plt.got, placing the result in a
subset of the top-bits that are not valid virtual addresses. The PLT entry
may authenticate these top-bits using the AUTIA instruction before
branching to the destination. Use of PAC in PLT sequences is a contract
between the dynamic loader and the static linker, it is independent of
whether the relocatable objects use PAC.
BTI and PAC are independent features that can be combined. So we can have
several combinations of PLT:
- Standard with no BTI or PAC
- BTI PLT with "BTI c" as first instruction.
- PAC PLT with "AUTIA1716" before the indirect branch to X17.
- BTIPAC PLT with "BTI c" as first instruction and "AUTIA1716" before the
first indirect branch to X17.
The use of BTI and PAC in relocatable object files are encoded by feature
bits in the .note.gnu.property section in a similar way to Intel CET. There
is one AArch64 specific program property GNU_PROPERTY_AARCH64_FEATURE_1_AND
and two target feature bits defined:
- GNU_PROPERTY_AARCH64_FEATURE_1_BTI
-- All executable sections are compatible with BTI.
- GNU_PROPERTY_AARCH64_FEATURE_1_PAC
-- All executable sections have return address signing enabled.
Due to the properties of FEATURE_1_AND the static linker can tell when all
input relocatable objects have the BTI and PAC feature bits set. The static
linker uses this to enable the appropriate PLT sequence.
Neither -> standard PLT
GNU_PROPERTY_AARCH64_FEATURE_1_BTI -> BTI PLT
GNU_PROPERTY_AARCH64_FEATURE_1_PAC -> PAC PLT
Both properties -> BTIPAC PLT
In addition to the .note.gnu.properties there are two new command line
options:
--force-bti : Act as if all relocatable inputs had
GNU_PROPERTY_AARCH64_FEATURE_1_BTI and warn for every relocatable object
that does not.
--pac-plt : Act as if all relocatable inputs had
GNU_PROPERTY_AARCH64_FEATURE_1_PAC. As PAC is a contract between the loader
and static linker no warning is given if it is not present in an input.
Two processor specific dynamic tags are used to communicate that a non
standard PLT sequence is being used.
DTI_AARCH64_BTI_PLT and DTI_AARCH64_BTI_PAC.
Differential Revision: https://reviews.llvm.org/D62609
llvm-svn: 362793
It was added by D46654 but is actually never used.
R_PPC64_CALL_PLT (was: R_PPC_CALL_PLT) is a static link-time constant.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62994
llvm-svn: 362788
When a function is excluded via comdat we shouldn't add it to the
final list of init functions.
Differential Revision: https://reviews.llvm.org/D62983
llvm-svn: 362769
Many -static/-no-pie/-shared/-pie applications linked against glibc or musl
should work with this patch. This also helps FreeBSD PowerPC64 to migrate
their lib32 (PR40888).
* Fix default image base and max page size.
* Support new-style Secure PLT (see below). Old-style BSS PLT is not
implemented, so it is not suitable for FreeBSD rtld now because it doesn't
support Secure PLT yet.
* Support more initial relocation types:
R_PPC_ADDR32, R_PPC_REL16*, R_PPC_LOCAL24PC, R_PPC_PLTREL24, and R_PPC_GOT16.
The addend of R_PPC_PLTREL24 is special: it decides the call stub PLT type
but it should be ignored for the computation of target symbol VA.
* Support GNU ifunc
* Support .glink used for lazy PLT resolution in glibc
* Add a new thunk type: PPC32PltCallStub that is similar to PPC64PltCallStub.
It is used by R_PPC_REL24 and R_PPC_PLTREL24.
A PLT stub used in -fPIE/-fPIC usually loads an address relative to
.got2+0x8000 (-fpie/-fpic code uses _GLOBAL_OFFSET_TABLE_ relative
addresses).
Two .got2 sections in two object files have different addresses, thus a PLT stub
can't be shared by two object files. To handle this incompatibility,
change the parameters of Thunk::isCompatibleWith to
`const InputSection &, const Relocation &`.
PowerPC psABI specified an old-style .plt (BSS PLT) that is both
writable and executable. Linkers don't make separate RW- and RWE segments,
which causes all initially writable memory (think .data) executable.
This is a big security concern so a new PLT scheme (secure PLT) was developed to
address the security issue.
TLS will be implemented in D62940.
glibc older than ~2012 requires .rela.dyn to include .rela.plt, it can
not handle the DT_RELA+DT_RELASZ == DT_JMPREL case correctly. A hack
(not included in this patch) in LinkerScript.cpp addOrphanSections() to
work around the issue:
if (Config->EMachine == EM_PPC) {
// Older glibc assumes .rela.dyn includes .rela.plt
Add(In.RelaDyn);
if (In.RelaPlt->isLive() && !In.RelaPlt->Parent)
In.RelaDyn->getParent()->addSection(In.RelaPlt);
}
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62464
llvm-svn: 362721
We were not previously testing the comdat exclusion in bitcode objects
because we were linking two copies of the .bc file and the
`linkonce_odr` linkage type was removing the duplicate `_start` at
the LTO stage.
Now we link an bitcode and non-bitcode version both of which contains a
copy of _start. We link them in both orders, which means this test will
fail if comdat exclusion is not working correctly in bitcode parsing.
Differential Revision: https://reviews.llvm.org/D62923
llvm-svn: 362650
With r362638, llc doesn't support -relocation-model=pic with non-Emscripten
triples. Update these tests in lld which use -relocation-model=pic to also
use Emscripten triples.
llvm-svn: 362645
Any symbols defined in the LTO object are by definition the ones we
want in the final output so we skip the comdat group checking in those
cases.
This change makes the ELF code more explicit about this and means
that wasm and ELF do this in the same way.
Differential Revision: https://reviews.llvm.org/D62884
llvm-svn: 362625
Although many relocatable objects will have a single
GNU_PROPERTY_X86_FEATURE_1_AND in the .note.gnu.property section it is
permissible to have more than one, and there are tests in ld.bfd that use
it. The behavior that ld.bfd follows is to set the feature bit for a
relocatable object if any of the GNU_PROPERTY_X86_FEATURE_1_AND
have the feature bit set.
Differential Revision: https://reviews.llvm.org/D62862
llvm-svn: 362591
The age field is only there to say how many times an OBJ or a PDB was incrementally linked. It shouldn't be used to validate the link between the OBJ and the PDB.
Differential Revision: https://reviews.llvm.org/D62837
llvm-svn: 362572
Summary:
Make `wasm-ld --verbose` show data section start virtual address and name
as well, instead of just showing the size. This makes it much easier to
track which global variable is in which address when used in conjunction
with `--no-merge-data-sections`.
Patch by Guanzhong Chen
Reviewers: tlively, aheejin, sbc100, ruiu
Reviewed By: sbc100, ruiu
Subscribers: ruiu, dschuff, jgravelle-google, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62834
llvm-svn: 362548
Summary:
With -r or --emit-relocs, we warn `STT_SECTION symbol should be defined`
on relocations to discarded section symbol. This was added as an error
in rLLD319404, but was not so effective before D61583 (it turned the
error to a warning).
Relocations from .eh_frame .debug* .zdebug* .gcc_except_table to
discarded .text are very common and somewhat expected. Don't warn/error
on them. As a reference, ld.bfd has a similar logic in
_bfd_elf_default_action_discarded() to allow these cases.
Delete invalid-undef-section-symbol.test because what it intended to
check is now covered by the updated comdat-discarded-reloc.s
Delete relocatable-eh-frame.s because we allow relocations from
.eh_frame as a special case now.
Reviewers: grimar, phosek, ruiu, espindola
Reviewed By: ruiu
Subscribers: emaste, arichardson, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62840
llvm-svn: 362497
We currently (ab)use the Live bit on output sections to track whether
the section has ever had an input section added to it, and then later
use it during orphan placement. This will conflict with one of my upcoming
partition-related changes that will assign all output sections to a partition
(thus marking them as live) so that they can be added to the correct segment
by the code that creates program headers.
Instead of using the Live bit for this purpose, create a new flag and
start using it to track the property explicitly.
Differential Revision: https://reviews.llvm.org/D62348
llvm-svn: 362444
Summary:
- Fixes inline call frame line table display in windbg.
- Improve llvm-pdbutil to dump extra file ids.
- Warn on unknown subsections so we don't have this kind of bug in the
future.
Reviewers: inglorion, akhuang, aganea
Subscribers: eraman, zturner, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62701
llvm-svn: 362429
We need to have all input files ready before doing debuginfo type merging.
This patch is moving the late PDB type server discovery much earlier in the process, when the explicit inputs (OBJs, LIBs) are loaded.
The short term goal is to parallelize type merging.
Differential Revision: https://reviews.llvm.org/D60095
llvm-svn: 362393
The following abstract relocation types (RelExpr) are PPC64 ELFv2 ABI specific,
not used by PPC32. So rename them to prevent confusion when the PPC32 port is improved.
* R_PPC_CALL R_PPC_CALL_PLT:
R_PPC_CALL_PLT represents R_PPC64_REL14 and R_PPC64_REL24.
If the function is not preemptable, R_PPC_CALL_PLT can be optimized to R_PPC_CALL:
the formula adjusts the symbol VA from the global entry point to the local entry point.
* R_PPC_TOC: represents R_PPC64_TOC. We don't have a test. Add one to ppc64-relocs.s
Rename it to R_PPC64_TOCBASE because `@tocbase` is the assembly form.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62800
llvm-svn: 362359
In ELF v2 ABI, R_PPC64_GOT_DTPREL16* are not relaxed.
This family of relocation types are used for variables outside of 2GiB
of the TLS block. 2 instructions cannot materialize a DTPREL offset that
is not 32-bit.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62737
llvm-svn: 362357
Fixes the remaining issue of PR41673 after D61186: with `/DISCARD/ { ... } :NONE`,
we may create an output section named `/DISCARD/`.
Note, if an input section is named `/DISCARD/`, ld.bfd discards it but
lld keeps it. It is probably not worth copying this behavior as it is unrealistic.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62768
llvm-svn: 362356
(1) {gcc,clang} -fuse-ld=bfd -pie -fPIE -nostdlib a.c => .interp created
(2) {gcc,clang} -fuse-ld=lld -pie -fPIE -nostdlib a.c => .interp not created
(3) {gcc,clang} -fuse-ld=lld -pie -fPIE -nostdlib a.c a.so => .interp created
The inconsistency of (2) is due to the condition `!Config->SharedFiles.empty()`.
To make lld behave more like ld.bfd, we could change the condition to:
Config->HasDynSymTab && !Config->DynamicLinker.empty() && Script->needsInterpSection();
However, that would bring another inconsistency as can be observed with:
(4) {gcc,clang} -fuse-ld=bfd -no-pie -nostdlib a.c => .interp not created
So instead, use `!Config->DynamicLinker.empty() && Script->needsInterpSection()`,
which is both simple and consistent in these cases.
The inconsistency of (4) likely originated from ld.bfd and gold's choice to have a default --dynamic-linker.
Their condition to create .interp is ANDed with (not -shared).
Since lld doesn't have a default --dynamic-linker,
compiler drivers (gcc/clang) don't pass --dynamic-linker for -shared,
and direct ld users are not supposed to specify --dynamic-linker for -shared,
we do not need the condition !Config->Shared.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62765
llvm-svn: 362355
Delete aarch64-got.s because it is covered by aarch64-tls-iele.s
Merge got-aarch64.s into aarch64-fpic-got.s by adding disassembly to the latter
Create aarch64-gnu-ifunc-nonpreemptable to unify aarch64-gnu-ifunc3.s (position-dependent executable) and aarch64-gnu-ifunc-address-pie.s (PIE)
Rename aarch64-got-reloc.s to aarch64-got-weak-undef.s
Add --no-show-raw-insn to llvm-objdump -d RUN lines
Add -pie test to arch64-tls-iele.s
Delete aarch64-tls-pie.s: it is covered by arch64-tls-iele.s and aarch64-tls-le.s
Rename aarch64-copy2.s to aarch64-nopic-plt.s: "copy2" gives false impression that the test is related to copy relocation
llvm-svn: 362294
GotEntrySize and GotPltEntrySize were added in D22288. Later, with
the introduction of wordsize() (then Config->Wordsize), they become
redundant, because there is no target that sets GotEntrySize or
GotPltEntrySize to a number different from Config->Wordsize.
Reviewed By: grimar, ruiu
Differential Revision: https://reviews.llvm.org/D62727
llvm-svn: 362220
Symbols relative to discarded comdat sections are Undefined instead of
Defined now (after D59649 and D61583). The `== &InputSection::Discarded`
test becomes dead. I cannot find a test related to this behavior.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62725
llvm-svn: 362218
The test (the only test that checks getLinkerScriptLocation()) deleted
by r358652 can be restored by replacing R_X86_64_PLT32 with
R_X86_64_PC32, and changing -pie to -shared (preemptable). Then, the
symbol will not be a link-time constant and a -fPIC error will be
issued.
llvm-svn: 362207
Summary:
Add the names of the input files responsible for each error to the
messages.
Reviewers: sbc100, azakai
Subscribers: dschuff, jgravelle-google, aheejin, sunfish, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62704
llvm-svn: 362162
Summary:
This updates all places in documentation that refer to "Mac OS X", "OS X", etc.
to instead use the modern name "macOS" when no specific version number is
mentioned.
If a specific version is mentioned, this attempts to use the OS name at the time
of that version:
* Mac OS X for 10.0 - 10.7
* OS X for 10.8 - 10.11
* macOS for 10.12 - present
Reviewers: JDevlieghere
Subscribers: mgorny, christof, arphaman, cfe-commits, lldb-commits, libcxx-commits, llvm-commits
Tags: #clang, #lldb, #libc, #llvm
Differential Revision: https://reviews.llvm.org/D62654
llvm-svn: 362113
This is a leftover from r325379.
The intention of this test was to check in a non-pic link, R_X86_64_PC32
to a STT_FUNC created a PLT. However, after the llvm-mc change in
r325569, this code path is no longer exercised. Use the r325379 trick to
keep testing R_X86_64_PC32.
llvm-svn: 362095
For the Local Dynamic case of TLSDESC, _TLS_MODULE_BASE_ is defined as a
special TLS symbol that makes:
1) Without relaxation: it produces a dynamic TLSDESC relocation that
computes 0. Adding @dtpoff to access a TLS symbol.
2) With LD->LE relaxation: _TLS_MODULE_BASE_@tpoff = 0 (lowest address in
the TLS block). Adding @tpoff to access a TLS symbol.
For 1), this saves dynamic relocations and GOT slots as otherwise
(General Dynamic) we would create an R_X86_64_TLSDESC and reserve two
GOT slots for each symbol.
Add ElfSym::TlsModuleBase and change the signature of getTlsTpOffset()
to special case _TLS_MODULE_BASE_.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D62577
llvm-svn: 362078
This data structure is only needed temporarily while symbols are being
created.
This is a followup on rL361678.
Differential Revision: https://reviews.llvm.org/D62548
llvm-svn: 361977
