Commit Graph

551 Commits

Author SHA1 Message Date
Fangrui Song
47cfe8f321 [ELF] Fix variable names in comments after VariableName -> variableName change
Also fix some typos.

llvm-svn: 366181
2019-07-16 05:50:45 +00:00
Rui Ueyama
136d27ab4d [Coding style change][lld] Rename variables for non-ELF ports
This patch does the same thing as r365595 to other subdirectories,
which completes the naming style change for the entire lld directory.

With this, the naming style conversion is complete for lld.

Differential Revision: https://reviews.llvm.org/D64473

llvm-svn: 365730
2019-07-11 05:40:30 +00:00
Rui Ueyama
3837f4273f [Coding style change] Rename variables so that they start with a lowercase letter
This patch is mechanically generated by clang-llvm-rename tool that I wrote
using Clang Refactoring Engine just for creating this patch. You can see the
source code of the tool at https://reviews.llvm.org/D64123. There's no manual
post-processing; you can generate the same patch by re-running the tool against
lld's code base.

Here is the main discussion thread to change the LLVM coding style:
https://lists.llvm.org/pipermail/llvm-dev/2019-February/130083.html
In the discussion thread, I proposed we use lld as a testbed for variable
naming scheme change, and this patch does that.

I chose to rename variables so that they are in camelCase, just because that
is a minimal change to make variables to start with a lowercase letter.

Note to downstream patch maintainers: if you are maintaining a downstream lld
repo, just rebasing ahead of this commit would cause massive merge conflicts
because this patch essentially changes every line in the lld subdirectory. But
there's a remedy.

clang-llvm-rename tool is a batch tool, so you can rename variables in your
downstream repo with the tool. Given that, here is how to rebase your repo to
a commit after the mass renaming:

1. rebase to the commit just before the mass variable renaming,
2. apply the tool to your downstream repo to mass-rename variables locally, and
3. rebase again to the head.

Most changes made by the tool should be identical for a downstream repo and
for the head, so at the step 3, almost all changes should be merged and
disappear. I'd expect that there would be some lines that you need to merge by
hand, but that shouldn't be too many.

Differential Revision: https://reviews.llvm.org/D64121

llvm-svn: 365595
2019-07-10 05:00:37 +00:00
Fangrui Song
5c4bbc2746 [ELF] Allow placing non-string SHF_MERGE sections with different alignments into the same MergeSyntheticSection
The difference from D63432/r365015 is that this patch does not place
SHF_STRINGS sections with different alignments into the same
MergeSyntheticSection. Doing that would:

(1) create unnecessary padding and thus waste space.
  Add a test tail-merge-string-align2.s to check no extra padding is created.
(2) make some input sections unaligned when tail merge (-O2) is enabled.
  The alignment of MergeTailAlignment::Builder was out of sync in D63432.
  MOVAPS on such unaligned strings can raise SIGSEGV.

This should fix PR42289: the Linux kernel has a use case that input
files have .rodata.cst32 sections with different alignments. The
expectation (and what ld.bfd and gold do) is that in the -r link, there
is only one .rodata.cst32 (SHF_MERGE sections with different alignments
can be combined), but lld currently creates one for each different
alignment.

The current merging strategy:

1) Group SHF_MERGE sections by (name, sh_flags, sh_entsize and
   sh_addralign). Merging is performed among a group, even if -O0 is specified.
2) Create one output section for each group. This is a special case in
   addInputSec().

This patch changes 1) to:

1) Group SHF_MERGE sections by (name, sh_flags, sh_entsize).
   Merging is performed among a group, even if -O0 is specified.

We will thus create just one .rodata.cst32 . This also improves merging
efficiency when sections with the same name but different alignments are
combined.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D64200

llvm-svn: 365139
2019-07-04 13:33:27 +00:00
Fangrui Song
b9bc9f67f5 Revert D63432 "[ELF] Allow placing SHF_MERGE sections with different alignments into the same MergeSyntheticSection"
This reverts r365015.

David Zarzycki reported this change broke stage2 and stage3 tests.  The
root cause is still not very clear, but I guess some SHF_MERGE sections
with the same name have different alignments. They were not merged
before but were merged after r365015.

Something that assumes address uniqueness of such mergeable data caused
the bug.

llvm-svn: 365048
2019-07-03 15:26:54 +00:00
Fangrui Song
347692e2de [ELF] Allow placing SHF_MERGE sections with different alignments into the same MergeSyntheticSection
This should fix PR42289: the Linux kernel has a use case that input
files have .rodata.cst32 sections with different alignments. The
expectation (and what ld.bfd and gold do) is that in the -r link, there
is only one .rodata.cst32 (SHF_MERGE sections with different alignments
can be combined), but lld currently creates one for each different
alignment.

The current merging strategy:

1) Group SHF_MERGE sections by (name, sh_flags, sh_entsize and
   sh_addralign). String merging is performed among a group, even if -O0 is specified.
2) Create one output section for each group. This is a special case in
   addInputSec().

This patch changes 1) to:

1) Group SHF_MERGE sections by (name, sh_flags, sh_entsize).
   String merging is performed among a group, even if -O0 is specified.

We will thus create just one .rodata.cst32 . This also improves merging
efficiency when sections with the same name but different alignments are
combined.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D63432

llvm-svn: 365015
2019-07-03 10:03:49 +00:00
Igor Kudrin
fd0ad4b24d [ELF] Do not produce DT_JMPREL and DT_PLTGOT if .rela.plt is empty.
If .rela.plt is mentioned in a linker script, it might be preserved
even if it is empty. In that case, LLD created DT_JMPREL and DT_PLTGOT
dynamic tags. When the tags exist, a dynamic loader writes values into
reserved slots in .got.plt to support lazy symbol resolution.
The problem is that, in fact, the linker has not reserved that space,
and the writing may occur into the memory allocated for something else.

Differential Revision: https://reviews.llvm.org/D63869

llvm-svn: 364639
2019-06-28 10:14:14 +00:00
Fangrui Song
5b4285d82d [ELF][RISCV] Create dummy .sdata for __global_pointer$ if .sdata does not exist
If .sdata is absent, linker synthesized __global_pointer$ gets a section index of SHN_ABS.
(ld.bfd has a similar issue: binutils PR24678)

Scrt1.o may use `lla gp, __global_pointer$` to reference the symbol PC
relatively. In -pie/-shared mode, lld complains if a PC relative
relocation references an absolute symbol (SHN_ABS) but ld.bfd doesn't:

    ld.lld: error: relocation R_RISCV_PCREL_HI20 cannot refer to lute symbol: __global_pointer$

Let the reference of __global_pointer$ to force creation of .sdata to
fix the problem. This is similar to _GLOBAL_OFFSET_TABLE_, which forces
creation of .got or .got.plt .

Also, change the visibility from STV_HIDDEN to STV_DEFAULT and don't
define the symbol for -shared. This matches ld.bfd, though I don't
understand why it uses STV_DEFAULT.

Reviewed By: ruiu, jrtc27

Differential Revision: https://reviews.llvm.org/D63132

llvm-svn: 363351
2019-06-14 02:14:53 +00:00
Peter Collingbourne
0282898586 ELF: Create synthetic sections for loadable partitions.
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
2019-06-07 17:57:58 +00:00
Peter Smith
e208208a31 [ELF][AArch64] Support for BTI and PAC
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
2019-06-07 13:00:17 +00:00
Fangrui Song
82442adfc0 [PPC32] Improve the 32-bit PowerPC port
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
2019-06-06 17:03:00 +00:00
Rui Ueyama
2057f8366a Read .note.gnu.property sections and emit a merged .note.gnu.property section.
This patch also adds `--require-cet` option for the sake of testing.
The actual feature for IBT-aware PLT is not included in this patch.

This is a part of https://reviews.llvm.org/D59780. Submitting this
first should make it easy to work with a related change
(https://reviews.llvm.org/D62609).

Differential Revision: https://reviews.llvm.org/D62853

llvm-svn: 362579
2019-06-05 03:04:46 +00:00
Fangrui Song
e98baf8631 [ELF] Delete GotEntrySize and GotPltEntrySize
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
2019-05-31 10:35:45 +00:00
Peter Collingbourne
ba2816be82 ELF: Add basic partition data structures and behaviours.
This change causes us to read partition specifications from partition
specification sections and split output sections into partitions according
to their reachability from partition entry points.

This is only the first step towards a full implementation of partitions. Later
changes will add additional synthetic sections to each partition so that
they can be loaded independently.

Differential Revision: https://reviews.llvm.org/D60353

llvm-svn: 361925
2019-05-29 03:55:20 +00:00
Fangrui Song
055906e1e5 [ELF] -z combreloc: sort dynamic relocations by (!is_relative,symbol_index,r_offset)
We currently sort dynamic relocations by (!is_relative,symbol_index).
Add r_offset as the third key. This makes `readelf -r` debugging easier
(relocations to the same symbol are ordered by r_offset).

Refactor the test combreloc.s (renamed from combrelocs.s) to check
R_X86_64_RELATIVE, and delete --expand-relocs.

The difference from the reverted D61477 is that we keep !is_relative as
the first key. In local dynamic TLS model, DTPMOD (e.g.
R_ARM_TLS_DTPMOD32 R_X86_64_DTPMOD and R_PPC{,64}_DTPMOD) may use 0 as
the symbol index.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D62141

llvm-svn: 361164
2019-05-20 15:25:01 +00:00
Dmitri Gribenko
a2fbe2bcda Revert "[ELF] -z combreloc: sort dynamic relocations by (symbol_index,r_offset)"
This reverts commit r361125.  This linker change breaks shared libraries
in some subtle way on x86_64.  (Specifically, gold segfaults when
loading the LLVMgold.so plugin linked with lldb with this patch.)

llvm-svn: 361150
2019-05-20 13:05:55 +00:00
Fangrui Song
9f1a6de631 [ELF] -z combreloc: sort dynamic relocations by (symbol_index,r_offset)
Fixes PR41692.

We currently sort dynamic relocations by (!is_relative,symbol_index).
Change it to (symbol_index,r_offset). We still place relative
relocations first because R_*_RELATIVE are the only dynamic relocations
with 0 symbol index (except on MIPS, which doesn't use DT_REL[A]COUNT
anyway).

This makes `readelf -r` debugging easier (relocations to the same symbol
are ordered by r_offset).

Refactor the test combreloc.s (renamed from combrelocs.s) to check
R_X86_64_RELATIVE, and delete --expand-relocs.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D61477

llvm-svn: 361125
2019-05-20 07:22:55 +00:00
Fangrui Song
ed4dbe6326 [ELF] --gdb-index: fix SIGSEGV when a DWARFAddressRange has invalid SectionIndex
See D61891: llvm had a bug that might create invalid (DW_AT_low_pc,DW_AT_high_pc) pairs or range list entries due to missing DW_AT_addr_base.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D61889

llvm-svn: 360679
2019-05-14 14:41:20 +00:00
Fangrui Song
32c0ebe615 Use llvm::stable_sort
Make some small adjustment while touching the code: make parameters
const, use less_first(), etc.

Differential Revision: https://reviews.llvm.org/D60989

llvm-svn: 358943
2019-04-23 02:42:06 +00:00
Fangrui Song
957c356ffe [ELF] Place SectionPiece::{Live,Hash} bit fields together
Summary:
We access Live and OutputOff (which may share the same memory location)
concurrently in 2 parallelForEachN loops. Separating them avoids subtle
data races like D41884/PR35788. This patch places Live and Hash
together.

2 reasons this is appealing:

1) Hash is immutable. Live is almost read-only - only written once in MarkLive.cpp where
   Hash is not accessed
2) we already discard low bits of Hash to decide ShardID. It doesn't
   matter much if we make 32-bit Hash to 31-bit.

   For a huge internal clang -O3 executable (1.6GiB),
   `Strings` in StringTableBuilder::finalizeStringTable contains at most 310253 elements.
   The expected number of pair-wise collisions 2^(-31) * C(310253,2) ~= 22.41 is too small to have a negative impact on performance.
   Actually, my benchmark shows there is actually a minor performance improvement.

Differential Revision: https://reviews.llvm.org/D60765

llvm-svn: 358645
2019-04-18 07:46:09 +00:00
Peter Collingbourne
97d25e068f ELF: Move build id computation to Writer. NFCI.
With partitions, each partition should have the same build id. This means
that the build id needs to be only computed once, otherwise we will end up
with different build ids in each partition as a result of the file contents
changing. This change moves the computation of the build id into Writer so
that it only happens once.

Differential Revision: https://reviews.llvm.org/D60342

llvm-svn: 358536
2019-04-16 22:45:14 +00:00
Fangrui Song
abc068fc59 [ELF] Fix typo: .symtab_shndxr -> .symtab_shndx
The typo was introduced to llvm MC in rL204769 (fixed in rL358247) and then to lld.

Also, for relocatable-many-sections.s, the size of .symtab changed at some point and the formula needs update.

llvm-svn: 358248
2019-04-12 02:20:52 +00:00
Peter Collingbourne
d3e207057f ELF: Move verneed tracking data structures out of VersionNeedSection.
For partitions I intend to use the same set of version indexes in
each partition for simplicity. Since each partition will need its own
VersionNeedSection this will require moving the verneed tracking out of
VersionNeedSection. The way I've done this is to move most of the tracking
into SharedFile. What will eventually become the per-partition tracking
still lives in VersionNeedSection.

As a bonus the code gets a little simpler and more consistent with how we
handle verdef.

Differential Revision: https://reviews.llvm.org/D60307

llvm-svn: 357926
2019-04-08 17:48:05 +00:00
Peter Collingbourne
cc1618e668 ELF: De-template SharedFile. NFCI.
Differential Revision: https://reviews.llvm.org/D60305

llvm-svn: 357925
2019-04-08 17:35:55 +00:00
Peter Collingbourne
a9e847238e ELF: Perform per-section .ARM.exidx processing during combineEhFrameSections(). NFCI.
And rename the function to combineEhSections(). This makes the processing
of .ARM.exidx even more similar to .eh_frame and means that we can avoid an
additional loop over InputSections.

Differential Revision: https://reviews.llvm.org/D60026

llvm-svn: 357417
2019-04-01 18:01:18 +00:00
Fangrui Song
d83fb24533 [ELF] Rename SyntheticSection::empty to more appropriate isNeeded() with opposite meaning
Summary:
Some synthetic sections can be empty while still being needed, thus they
can't be removed by removeUnusedSyntheticSections(). Rename this member
function to more appropriate isNeeded() with the opposite meaning.

No functional change intended.

Reviewers: ruiu, espindola

Reviewed By: ruiu

Subscribers: jhenderson, grimar, emaste, arichardson, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59982

llvm-svn: 357377
2019-04-01 08:16:08 +00:00
Rui Ueyama
68b9f45fee Replace typedef A B with using B = A. NFC.
I did this using Perl.

Differential Revision: https://reviews.llvm.org/D60003

llvm-svn: 357372
2019-04-01 00:11:24 +00:00
Peter Smith
3ce9af9370 [ELF][ARM] Recommit Redesign of .ARM.exidx handling to use a SyntheticSection
Recommit r356666 with fixes for buildbot failure, as well as handling for
--emit-relocs, which we decide not to emit any relocation sections as the
table is already position independent and an offline tool can deduce the
relocations.

Instead of creating extra Synthetic .ARM.exidx sections to account for
gaps in the table, create a single .ARM.exidx SyntheticSection that can
derive the contents of the gaps from a sorted list of the executable
InputSections. This has the benefit of moving the ARM specific code for
SyntheticSections in SHF_LINK_ORDER processing and the table merging code
into the ARM specific SyntheticSection. This also makes it easier to create
EXIDX_CANTUNWIND table entries for executable InputSections that don't
have an associated .ARM.exidx section.

Fixes pr40277

Differential Revision: https://reviews.llvm.org/D59216

llvm-svn: 357160
2019-03-28 11:10:20 +00:00
Fangrui Song
210949a221 [ELF] Change GOT*_FROM_END (relative to end(.got)) to GOTPLT* (start(.got.plt))
Summary:
This should address remaining issues discussed in PR36555.

Currently R_GOT*_FROM_END are exclusively used by x86 and x86_64 to
express relocations types relative to the GOT base. We have
_GLOBAL_OFFSET_TABLE_ (GOT base) = start(.got.plt) but end(.got) !=
start(.got.plt)

This can have problems when _GLOBAL_OFFSET_TABLE_ is used as a symbol, e.g.
glibc dl_machine_dynamic assumes _GLOBAL_OFFSET_TABLE_ is start(.got.plt),
which is not true.

  extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden;
  return _GLOBAL_OFFSET_TABLE_[0]; // R_X86_64_GOTPC32

In this patch, we

* Change all GOT*_FROM_END to GOTPLT* to fix the problem.
* Add HasGotPltOffRel to denote whether .got.plt should be kept even if
  the section is empty.
* Simplify GotSection::empty and GotPltSection::empty by setting
  HasGotOffRel and HasGotPltOffRel according to GlobalOffsetTable early.

The change of R_386_GOTPC makes X86::writePltHeader simpler as we don't
have to compute the offset start(.got.plt) - Ebx (it is constant 0).

We still diverge from ld.bfd (at least in most cases) and gold in that
.got.plt and .got are not adjacent, but the advantage doing that is
unclear.

Reviewers: ruiu, sivachandra, espindola

Subscribers: emaste, mehdi_amini, arichardson, dexonsmith, jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59594

llvm-svn: 356968
2019-03-25 23:46:19 +00:00
Rui Ueyama
d2e0ed7755 Simplify PltSection.
Previously, `Entries` contains pairs of symbols and their indices.
The indices are always 0, x, 2x, 3x, ..., where x is the size of
relocation entry. We didn't have to store that values because we can
compute them when we consume them.

llvm-svn: 356812
2019-03-22 21:17:25 +00:00
Peter Smith
54dab70bb7 [ELF][ARM] Revert Redesign of .ARM.exidx handling to use a SyntheticSection
There is a reproducible buildbot failure (segfault) on the 2 stage
clang-cmake-armv8-lld bot. Reverting while I investigate.

Differential Revision: https://reviews.llvm.org/D59216

llvm-svn: 356684
2019-03-21 17:17:54 +00:00
Peter Smith
d3511a214e [ELF][ARM] Redesign of .ARM.exidx handling to use a SyntheticSection
Instead of creating extra Synthetic .ARM.exidx sections to account for
gaps in the table, create a single .ARM.exidx SyntheticSection that can
derive the contents of the gaps from a sorted list of the executable
InputSections. This has the benefit of moving the ARM specific code for
SyntheticSections in SHF_LINK_ORDER processing and the table merging code
into the ARM specific SyntheticSection. This also makes it easier to create
EXIDX_CANTUNWIND table entries for executable InputSections that don't
have an associated .ARM.exidx section.

Fixes pr40277

Differential Revision: https://reviews.llvm.org/D59216

llvm-svn: 356666
2019-03-21 14:06:40 +00:00
Fangrui Song
1092fc9057 [ELF] Allow sh_entsize to be unrelated to sh_addralign and not a power of 2
Summary:
This implements Rui Ueyama's idea in PR39044.
I've checked that ld.bfd and gold do not have the power-of-2 requirement
and do not require sh_entsize to be a multiple of sh_align.

Now on the updated test merge-entsize.s, all the 3 linkers happily
create .rodata that is not 3-byte aligned.

This has a use case in Linux arch/x86/crypto/sha512-avx2-asm.S
It uses sh_entsize of 640, which is not a power of 2.
See https://github.com/ClangBuiltLinux/linux/issues/417

Reviewers: ruiu, espindola

Reviewed By: ruiu

Subscribers: nickdesaulniers, E5ten, emaste, arichardson, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59478

llvm-svn: 356428
2019-03-18 23:49:18 +00:00
Peter Collingbourne
8a28673a2e ELF: Don't add .dynamic strings to .dynstr early.
This does not appear to be necessary because StringTableSection does not
need to be finalized, which also means that we can remove the call to
finalizeSynthetic on .dynstr.

Differential Revision: https://reviews.llvm.org/D59240

llvm-svn: 355977
2019-03-12 20:58:34 +00:00
Peter Collingbourne
5ee9abd4c8 ELF: De-template OutputSection::finalize() and MipsGotSection::build(). NFCI.
Differential Revision: https://reviews.llvm.org/D58810

llvm-svn: 355479
2019-03-06 03:07:57 +00:00
Peter Collingbourne
704dfd6e28 ELF: Extract a non-ELFT base class for VersionNeedSection.
We're going to need a separate VersionNeedSection for each partition, and
the partition data structure won't be templated.

With this the VersionTableSection class no longer needs ELFT, so detemplate it.

Differential Revision: https://reviews.llvm.org/D58808

llvm-svn: 355478
2019-03-06 03:07:48 +00:00
Peter Collingbourne
7fb9eabda5 ELF: Write .eh_frame_hdr explicitly after writing .eh_frame.
This lets us remove the special case from Writer::writeSections(), and also
fixes a bug where .eh_frame_hdr isn't necessarily written in the correct
order if a linker script moves .eh_frame and .eh_frame_hdr into the same
output section.

Differential Revision: https://reviews.llvm.org/D58795

llvm-svn: 355153
2019-02-28 23:11:35 +00:00
Peter Collingbourne
f9232b0c00 ELF: Remove dead code. NFCI.
RelocationBaseSection is not used in -r links, so Config->Relocatable will
always be false.

Differential Revision: https://reviews.llvm.org/D58489

llvm-svn: 354607
2019-02-21 18:53:58 +00:00
Simon Atanasyan
fae2a509fa [MIPS] Handle cross-mode (regular <-> microMIPS) jumps
The patch solves two tasks:

1. MIPS ABI allows to mix regular and microMIPS code and perform
cross-mode jumps. Linker needs to detect such cases and replace
jump/branch instructions by their cross-mode equivalents.

2. Other tools like dunamic linkers need to recognize cases when dynamic
table entries, e_entry field of an ELF header etc point to microMIPS
symbol. Linker should provide such information.

The first task is implemented in the `MIPS<ELFT>::relocateOne()` method.
New routine `fixupCrossModeJump` detects ISA mode change, checks and
replaces an instruction.

The main problem is how to recognize that relocation target is microMIPS
symbol. For absolute and section symbols compiler or assembler set the
less-significant bit of the symbol's value or sum of the symbol's value
and addend. And this bit signals to linker about microMIPS code. For
global symbols compiler cannot do the same trick because other tools like,
for example, disassembler wants to know an actual position of the symbol.
So compiler sets STO_MIPS_MICROMIPS flag in the `st_other` field.

In `MIPS<ELFT>::relocateOne()` method we have a symbol's value only and
cannot access any symbol's attributes. To pass type of the symbol
(regular/microMIPS) to that routine as well as other places where we
write a symbol value as-is (.dynamic section, `Elf_Ehdr::e_entry` field
etc) we set when necessary a less-significant bit in the `getSymVA`
function.

Differential revision: https://reviews.llvm.org/D40147

llvm-svn: 354311
2019-02-19 10:36:58 +00:00
Rui Ueyama
9efdd7ac5e [PPC64] Preserve LocalEntry when linking
On PowerPC64, it is necessary to keep the LocalEntry bits in st_other,
especially when -r is used. Otherwise, when the resulting object is used
in a posterior linking, LocalEntry info will be unavailable and
functions may be called through the wrong entrypoint.

Patch by Leandro Lupori.

Differential Revision: https://reviews.llvm.org/D56782

llvm-svn: 354184
2019-02-15 23:11:18 +00:00
Peter Collingbourne
8331f61a51 ELF: Allow GOT relocs pointing to non-preemptable ifunc to resolve to an IRELATIVE where possible.
Non-GOT non-PLT relocations to non-preemptible ifuncs result in the
creation of a canonical PLT, which now takes the identity of the IFUNC
in the symbol table. This (a) ensures address consistency inside and
outside the module, and (b) fixes a bug where some of these relocations
end up pointing to the resolver.

Fixes (at least) PR40474 and PR40501.

Differential Revision: https://reviews.llvm.org/D57371

llvm-svn: 353981
2019-02-13 21:49:55 +00:00
Rui Ueyama
1b11e9e8a4 Remove a small header that is used only by one file. NFC.
llvm-svn: 353331
2019-02-06 19:28:23 +00:00
George Rimar
ae54e58b90 Recommit r353293 "[LLD][ELF] - Set DF_STATIC_TLS flag for i386 target."
With the following changes:
1) Compilation fix:
std::atomic<bool> HasStaticTlsModel = false; ->
std::atomic<bool> HasStaticTlsModel{false};

2) Adjusted the comment in code.

Initial commit message:

DF_STATIC_TLS flag indicates that the shared object or executable
contains code using a static thread-local storage scheme.

Patch checks if IE/LE relocations were used to check if the code uses
a static model. If so it sets the DF_STATIC_TLS flag.

Differential revision: https://reviews.llvm.org/D57749
----
Modified : /lld/trunk/ELF/Arch/X86.cpp
Modified : /lld/trunk/ELF/Config.h
Modified : /lld/trunk/ELF/SyntheticSections.cpp
Added : /lld/trunk/test/ELF/Inputs/i386-static-tls-model1.s
Added : /lld/trunk/test/ELF/Inputs/i386-static-tls-model2.s
Added : /lld/trunk/test/ELF/Inputs/i386-static-tls-model3.s
Added : /lld/trunk/test/ELF/Inputs/i386-static-tls-model4.s
Added : /lld/trunk/test/ELF/i386-static-tls-model.s
Modified : /lld/trunk/test/ELF/i386-tls-ie-shared.s
Modified : /lld/trunk/test/ELF/tls-dynamic-i686.s
Modified : /lld/trunk/test/ELF/tls-opt-iele-i686-nopic.s

llvm-svn: 353299
2019-02-06 14:43:30 +00:00
George Rimar
52fafcb919 Revert r353293 "[LLD][ELF] - Set DF_STATIC_TLS flag for i386 target."
It broke BB:
http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/43450
http://lab.llvm.org:8011/builders/lld-x86_64-freebsd/builds/27891

Error is:
tools/lld/ELF/Config.h:84:41: error: copying member subobject of type
'std::atomic<bool>' invokes deleted constructor std::atomic<bool> HasStaticTlsModel = false;

llvm-svn: 353297
2019-02-06 13:53:32 +00:00
George Rimar
da60ad220b [LLD][ELF] - Set DF_STATIC_TLS flag for i386 target.
DF_STATIC_TLS flag indicates that the shared object or executable
contains code using a static thread-local storage scheme.

Patch checks if IE/LE relocations were used to check if the code uses
a static model. If so it sets the DF_STATIC_TLS flag.

Differential revision: https://reviews.llvm.org/D57749

llvm-svn: 353293
2019-02-06 13:38:10 +00:00
Peter Collingbourne
ff35dbac47 ELF: Set sh_info on RelaIplt to point to the IgotPlt output section.
Previously we were setting it to the GotPlt output section, which is
incorrect on ARM where this section is in .got. In static binaries
this can lead to sh_info being set to -1 (because there is no .got.plt)
which results in various tools rejecting the output file.

Differential Revision: https://reviews.llvm.org/D57274

llvm-svn: 352413
2019-01-28 19:29:41 +00:00
Chandler Carruth
2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Mandeep Singh Grang
f9d76dc354 [lld] Use range-based llvm::sort
llvm-svn: 351612
2019-01-18 23:41:34 +00:00
Rui Ueyama
56c5343e5a Use error() instead of fatal() to report an invalid address range.
In this patch we also use toString() to stringize a section.

llvm-svn: 350070
2018-12-26 19:15:04 +00:00
David Blaikie
059b1c5e01 gdb-index: Handle errors when parsing ranges
When parsing CU ranges for gdb-index, handle the error (now propagated
up though the API lld is calling here - previously the error was
printed within the libDebugInfo API, not allowing lld to format or
handle the message at all) - including information about the object and
archive name, as well as failing the link.

llvm-svn: 349979
2018-12-22 00:31:05 +00:00