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2024-07-12[LLD] Extend special OpenBSD support, but scope under ELFOSABI (#97122)John Ericson1-0/+2
- Add support for `.openbsd.mutable` (rebaser's note) adapted from: https://github.com/openbsd/src/commit/bd249b5664da50f0178adea78250a7a0d8ea6566 New auto-coalescing sections removed In the linkers, collect objects in section "openbsd.mutable" and place them into a page-aligned region in the bss, with the right markers for kernel/ld.so to identify the region and skip making it immutable. While here, fix readelf/objdump versions to show all of this. ok miod kettenis - Add support for `.openbsd.syscalls` (rebaser's note) adapted from: https://github.com/openbsd/src/commit/42a61acefa8b3288ff2163fb55e934a3fee39974 Collect .openbsd.syscalls sections into a new PT_OPENBSD_SYSCALLS segment. This will be used soon to pin system calls to designated call sites. ok deraadt@ - Scope OpenBSD special section handling under that ELFOSABI As a preexisting comment in `ELF/Writer.cpp` says: > section names shouldn't be significant in ELF in spirit. so scoping OSABI-specific magic name hacks to just the OSABI in question limits the degree to which we deviate from that "spirit" for all other OSABIs. OpenBSD in particular is very fast moving, having added a number of special sections, etc. in recent years. It is unclear how possible / reasonable it is for upstream to implement all these features in any event, but scoping like this at least mitigates the fallout for other OSABIs systems which wish to be more slow-moving. Co-authored-by: deraadt <deraadt@openbsd.org>
2024-06-24[ELF] Postpone more linker script errorsFangrui Song1-2/+3
Since `assignAddresses` is executed more than once, error reporting during `assignAddresses` would be duplicated. Generalize #66854 to cover more errors. Note: address-related errors exposed in one invocation might not be errors in another invocation. Pull Request: https://github.com/llvm/llvm-project/pull/96361
2024-03-25[ELF] Fix unnecessary inclusion of unreferenced provide symbolsParth Arora1-1/+12
Previously, linker was unnecessarily including a PROVIDE symbol which was referenced by another unused PROVIDE symbol. For example, if a linker script contained the below code and 'not_used_sym' provide symbol is not included, then linker was still unnecessarily including 'foo' PROVIDE symbol because it was referenced by 'not_used_sym'. This commit fixes this behavior. PROVIDE(not_used_sym = foo) PROVIDE(foo = 0x1000) This commit fixes this behavior by using dfs-like algorithm to find all the symbols referenced in provide expressions of included provide symbols. This commit also fixes the issue of unused section not being garbage-collected if a symbol of the section is referenced by an unused PROVIDE symbol. Closes #74771 Closes #84730 Co-authored-by: Fangrui Song <i@maskray.me>
2024-03-06[ELF] Reject error-prone meta characters in input section descriptionFangrui Song1-2/+12
The lexer is overly permissive. When parsing file patterns in an input section description and there is a missing `)`, we would accept many non-sensible tokens (e.g. `}`) as patterns, leading to confusion, e.g. `*(SORT_BY_ALIGNMENT(SORT_BY_NAME(.text*)) } PROVIDE_HIDDEN(__code_end = .)` (#81804). Ideally, the lexer should be stateful to report more errors like GNU ld and get rid of hacks like `ScriptLexer::maybeSplitExpr`, but that would require a large rewrite of the lexer. For now, just reject certain non-wildcard meta characters to detect common mistakes. Pull Request: https://github.com/llvm/llvm-project/pull/84130
2024-02-13[lld] Add target support for SystemZ (s390x) (#75643)Ulrich Weigand1-0/+1
This patch adds full support for linking SystemZ (ELF s390x) object files. Support should be generally complete: - All relocation types are supported. - Full shared library support (DYNAMIC, GOT, PLT, ifunc). - Relaxation of TLS and GOT relocations where appropriate. - Platform-specific test cases. In addition to new platform code and the obvious changes, there were a few additional changes to common code: - Add three new RelExpr members (R_GOTPLT_OFF, R_GOTPLT_PC, and R_PLT_GOTREL) needed to support certain s390x relocations. I chose not to use a platform-specific name since nothing in the definition of these relocs is actually platform-specific; it is well possible that other platforms will need the same. - A couple of tweaks to TLS relocation handling, as the particular semantics of the s390x versions differ slightly. See comments in the code. This was tested by building and testing >1500 Fedora packages, with only a handful of failures; as these also have issues when building with LLD on other architectures, they seem unrelated. Co-authored-by: Tulio Magno Quites Machado Filho <tuliom@redhat.com>
2024-01-22[ELF] Add internal InputFile (#78944)Fangrui Song1-1/+2
Based on https://reviews.llvm.org/D45375 . Introduce a new InputFile kind `InternalKind`, use it for * `ctx.internalFile`: for linker-defined symbols and some synthesized `Undefined` * `createInternalFile`: for symbol assignments and --defsym I picked "internal" instead of "synthetic" to avoid confusion with SyntheticSection. Currently a symbol's file is one of: nullptr, ObjKind, SharedKind, BitcodeKind, BinaryKind. Now it's non-null (I plan to add an `assert(file)` to Symbol::Symbol and change `toString(const InputFile *)` separately). Debugging and error reporting gets improved. The immediate user-facing difference is more descriptive "File" column in the --cref output. This patch may unlock further simplification. Currently each symbol assignment gets its own `createInternalFile(cmd->location)`. Two symbol assignments in a linker script do not share the same file. Making the file the same would be nice, but would require non trivial code.
2024-01-08[ELF] OVERLAY: support optional start address and LMAFangrui Song1-9/+18
https://reviews.llvm.org/D44780 implemented rudimentary support for OVERLAY. The start address and `AT(ldaddr)` in `OVERLAY [start] : [NOCROSSREFS] [AT ( ldaddr )]` are not optional. In addition, there are two issues: * When the start address is `.`, subsequent sections don't share the address of the first overlay section. * When the first overlay section is empty and discardable, `p_paddr` is incorrectly zero. This is because a discarded section has a zero address, causing `prev->getLMA() + prev->size` where `prev` refers to the first section to evaluate to zero. This patch supports optional start address and LMA and fix the issues. Close #77265 Pull Request: https://github.com/llvm/llvm-project/pull/77272
2023-09-15[ELF] Correct a comment about ^=. NFCFangrui Song1-1/+1
GNU ld added ^= support in July 2023.
2023-09-14[ELF] Align the end of PT_GNU_RELRO associated PT_LOAD to a common-page-size ↵Fangrui Song1-9/+7
boundary (#66042) Close #57618: currently we align the end of PT_GNU_RELRO to a common-page-size boundary, but do not align the end of the associated PT_LOAD. This is benign when runtime_page_size >= common-page-size. However, when runtime_page_size < common-page-size, it is possible that `alignUp(end(PT_LOAD), page_size) < alignDown(end(PT_GNU_RELRO), page_size)`. In this case, rtld's mprotect call for PT_GNU_RELRO will apply to unmapped regions and lead to an error, e.g. ``` error while loading shared libraries: cannot apply additional memory protection after relocation: Cannot allocate memory ``` To fix the issue, add a padding section .relro_padding like mold, which is contained in the PT_GNU_RELRO segment and the associated PT_LOAD segment. The section also prevents strip from corrupting PT_LOAD program headers. .relro_padding has the largest `sortRank` among RELRO sections. Therefore, it is naturally placed at the end of `PT_GNU_RELRO` segment in the absence of `PHDRS`/`SECTIONS` commands. In the presence of `SECTIONS` commands, we place .relro_padding immediately before a symbol assignment using DATA_SEGMENT_RELRO_END (see also https://reviews.llvm.org/D124656), if present. DATA_SEGMENT_RELRO_END is changed to align to max-page-size instead of common-page-size. Some edge cases worth mentioning: * ppc64-toc-addis-nop.s: when PHDRS is present, do not append .relro_padding * avoid-empty-program-headers.s: when the only RELRO section is .tbss, it is not part of PT_LOAD segment, therefore we do not append .relro_padding. --- Close #65002: GNU ld from 2.39 onwards aligns the end of PT_GNU_RELRO to a max-page-size boundary (https://sourceware.org/PR28824) so that the last page is protected even if runtime_page_size > common-page-size. In my opinion, losing protection for the last page when the runtime page size is larger than common-page-size is not really an issue. Double mapping a page of up to max-common-page for the protection could cause undesired VM waste. Internally we had users complaining about 2MiB max-page-size applying to shared objects. Therefore, the end of .relro_padding is padded to a common-page-size boundary. Users who are really anxious can set common-page-size to match their runtime page size. --- 17 tests need updating as there are lots of change detectors.
2023-09-11[ELF] Respect orders of symbol assignments and DEFINED (#65866)Fangrui Song1-6/+11
Fix #64600: the currently implementation is minimal (see https://reviews.llvm.org/D83758), and an assignment like `__TEXT_REGION_ORIGIN__ = DEFINED(__TEXT_REGION_ORIGIN__) ? __TEXT_REGION_ORIGIN__ : 0;` (used by avr-ld[1]) leads to a value of zero (default value in `declareSymbol`), which is unexpected. Assign orders to symbol assignments and references so that for a script-defined symbol, the `DEFINED` results match users' expectation. I am unclear about GNU ld's exact behavior, but this hopefully matches its behavior in the majority of cases. [1]: https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=ld/scripttempl/avr.sc
2023-07-25[lld][ELF] Support LoongArchWANG Xuerui1-0/+2
This adds support for the LoongArch ELF psABI v2.00 [1] relocation model to LLD. The deprecated stack-machine-based psABI v1 relocs are not supported. The code is tested by successfully bootstrapping a Gentoo/LoongArch stage3, complete with common GNU userland tools and both the LLVM and GNU toolchains (GNU toolchain is present only for building glibc, LLVM+Clang+LLD are used for the rest). Large programs like QEMU are tested to work as well. [1]: https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html Reviewed By: MaskRay, SixWeining Differential Revision: https://reviews.llvm.org/D138135
2023-07-15[ELF] Support operator ^ and ^=Fangrui Song1-8/+19
GNU ld added ^ support in July 2023 and it looks like ^= is in plan as well. For now, we don't support `a^=0` (^= without a preceding space).
2023-07-05[ELF] Remove one unneeded unquote from D124266Fangrui Song1-1/+1
This one is unneeded after commit d60ef9338deb734541ff1c9d0771807815d5d9e6 (2023-02-03).
2023-07-05[lld/elf] support quote usage in section namesRoger Pau Monne1-5/+5
Section names used in ELF linker scripts can be quoted, but such quotes must not be propagated to the binary ELF section names. As such strip the quotes from the section names when processing them, and also strip them from linker script functions that take section names as parameters. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D124266
2023-06-15[ELF] << >>: make RHS less than 64Fangrui Song1-4/+4
The left/right shift linker script operators may trigger UB. E.g. in linkerscript/end-overflow-check.test, the initial REGION1__PADDED_SR_SHIFT is uint64_t(-3), cause the following expression to trigger an out-of-range shift in a ubsan build of lld. REGION1__PADDED_SR_SIZE = MAX(1 << REGION1__PADDED_SR_SHIFT, 32); Protect such UBs by making RHS less than 64.
2023-06-05[lld] StringRef::{starts,ends}with => {starts,ends}_with. NFCFangrui Song1-12/+12
The latter form is now preferred to be similar to C++20 starts_with. This replacement also removes one function call when startswith is not inlined.
2023-05-16Migrate {starts,ends}with_insensitive to {starts,ends}_with_insensitive (NFC)Kazu Hirata1-4/+4
This patch migrates uses of StringRef::{starts,ends}with_insensitive to StringRef::{starts,ends}_with_insensitive so that we can use names similar to those used in std::string_view. Note that the llvm/ directory has migrated in commit 6c3ea866e93003e16fc55d3b5cedd3bc371d1fde. I'll post a separate patch to deprecate StringRef::{starts,ends}with_insensitive. Differential Revision: https://reviews.llvm.org/D150506
2023-05-15[LLD][ELF] Add missing program header parsing to OVERLAYPeter Smith1-0/+1
In D72756 the change to add INPUT_SECTION_FLAGS inadvertantly removed the line to parse the program header assignment information for OutputSections within an OVERLAY. This change adds back the missing line and adds a test for it. Differential Revision: https://reviews.llvm.org/D150445
2023-03-29[lld][ARM][2/3]Big Endian support - Word invariant supportSimi Pallipurath1-0/+1
Changes: - Adding BE32 big endian Support for Arm. - Replace the writele and readle with their endian-aware versions. - Adding test cases for the big-endian be32 arm configuration. Patch by: Milosz Plichta. This patch merges all the changes from this patch https://reviews.llvm.org/D140203 as well. Reviewed By: peter.smith, MaskRay Differential Revision: https://reviews.llvm.org/D140202
2023-03-07[ELF] Add REVERSE input section description keywordJustin Cady1-0/+1
The `REVERSE` keyword is described here: https://sourceware.org/bugzilla/show_bug.cgi?id=27565 It complements `SORT` by allowing the order of input sections to be reversed. This is particularly useful for order-dependent sections such as .init_array, where `REVERSE` can be used to either detect static initialization order fiasco issues or as a mechanism to maintain .ctors element order while transitioning to the modern .init_array. Such a transition is described here: https://discourse.llvm.org/t/is-it-possible-to-manually-specify-init-array-order/68649 Differential Revision: https://reviews.llvm.org/D145381
2023-02-03[ELF] Support quoted output section namesFangrui Song1-1/+2
Similar to e7a7ad134fe182aad190cb3ebc441164470e92f5 and 2bf06d9345caeb26520be8e830c092683bbdf0f7 for other linker script syntax. Close https://github.com/llvm/llvm-project/issues/60496
2022-12-02[lld] Use std::nullopt instead of None (NFC)Kazu Hirata1-1/+1
This patch mechanically replaces None with std::nullopt where the compiler would warn if None were deprecated. The intent is to reduce the amount of manual work required in migrating from Optional to std::optional. This is part of an effort to migrate from llvm::Optional to std::optional: https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
2022-12-02Use CTAD on llvm::SaveAndRestoreJan Svoboda1-4/+4
Reviewed By: dblaikie Differential Revision: https://reviews.llvm.org/D139229
2022-12-01[lld][NFC] rename ELF alignment into addralignGuillaume Chatelet1-1/+1
2022-11-26[ELF] Change most llvm::Optional to std::optionalFangrui Song1-15/+15
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
2022-10-01[ELF] Move driver into ctx and remove indirection. NFCFangrui Song1-9/+9
This removes one global variable and removes GOT and unique_ptr indirection.
2022-10-01[ELF] Remove symtab indirection. NFCFangrui Song1-1/+1
Add LLVM_LIBRARY_VISIBILITY to remove unneeded GOT and unique_ptr indirection.
2022-07-24[ELF] Optimize some non-constant alignTo with alignToPowerOf2. NFCFangrui Song1-3/+4
My x86-64 lld executable is 2KiB smaller. .eh_frame writing gets faster as there were lots of divisions.
2022-06-25[ELF] Improve compound assignment testsFangrui Song1-2/+1
Also use strchr instead of is_contained.
2022-06-25[ELF] Support -= *= /= <<= >>= &= |= in symbol assignmentsFangrui Song1-5/+35
2022-06-25[ELF] Fix assertion failure when PROVIDE/HIDDEN/PROVIDE_HIDDEN does not have =Fangrui Song1-1/+8
2022-06-25[ELF] Allow an expression to follow = in a symbol assignmentFangrui Song1-4/+13
GNU ld doesn't require whitespace before =. Match it.
2022-06-25[ELF] Fix precedence of ? when there are 2 or more operators on the left ↵Fangrui Song1-2/+3
hand side For 1 != 1 <= 1 ? 1 : 2, the current code incorrectly considers that ? has a higher precedence than != (minPrec). Also, add a test for right associativity.
2022-06-25[ELF] Fix precedence of == and != in expressionsFangrui Song1-8/+9
In GNU ld, the == and != operators have lower precedence than < > <= >=. This behavior matches C.
2022-06-25[ELF] Support quoted name in the TARGET commandFangrui Song1-1/+1
2022-06-25[ELF] Support quoted symbol in the ENTRY commandFangrui Song1-1/+1
This matches GNU ld and matches other places we unquote the symbol name. Fixes #56208
2022-05-18[lld][ELF] Support BFD name elf32-avrBen Shi1-0/+1
Reviewed By: MaskRay differential Revision: https://reviews.llvm.org/D125544
2022-05-13[ELF] Disallow input section description without a filenameFangrui Song1-0/+2
GNU ld does not allow `.foo : { (*foo) }`, but we may recognize it as three input section descriptions: file "(" with any section name, file "*foo" with any section name, file ")" with any section name. Disallow the error-prone usage. Reviewed By: peter.smith Differential Revision: https://reviews.llvm.org/D125523
2022-05-04[ELF] Support custom sections between DATA_SEGMENT_ALIGN and ↵Fangrui Song1-0/+15
DATA_SEGMENT_RELRO_END We currently hard code RELRO sections. When a custom section is between DATA_SEGMENT_ALIGN and DATA_SEGMENT_RELRO_END, we may report a spurious `error: section: ... is not contiguous with other relro sections`. GNU ld makes such sections RELRO. glibc recently switched to default --with-default-link=no. This configuration places `__libc_atexit` and others between DATA_SEGMENT_ALIGN and DATA_SEGMENT_RELRO_END. This patch allows such a ld.bfd --verbose linker script to be fed into lld. Reviewed By: peter.smith Differential Revision: https://reviews.llvm.org/D124656
2022-03-08[ELF] Don't use multiple inheritance for OutputSection. NFCFangrui Song1-41/+40
Add an OutputDesc class inheriting from SectionCommand. An OutputDesc wraps an OutputSection. This change allows InputSection::getParent to be inlined. Differential Revision: https://reviews.llvm.org/D120650
2022-02-28[ELF] Change some non-null pointer parameters to references. NFCFangrui Song1-14/+14
To decrease difference for D120650. Also, rename some `OutputSection *sec` (and `cmd`) to the more common `osec`.
2022-02-23[ELF] Don't rely on Symbols.h's transitive inclusion of InputFiles.h. NFCFangrui Song1-0/+1
2022-02-17[ELF] Support (TYPE=<value>) to customize the output section typeFangrui Song1-5/+35
The current output section type allows to set the ELF section type to SHT_PROGBITS or SHT_NOLOAD. This patch allows an arbitrary section value to be specified. Some common SHT_* literal names are supported as well. ``` SECTIONS { note (TYPE=SHT_NOTE) : { BYTE(8) *(note) } init_array ( TYPE=14 ) : { QUAD(14) } fini_array (TYPE = SHT_FINI_ARRAY) : { QUAD(15) } } ``` When `sh_type` is specified, it is an error if an input section has a different type. Our syntax is compatible with GNU ld 2.39 (https://sourceware.org/bugzilla/show_bug.cgi?id=28841). Reviewed By: peter.smith Differential Revision: https://reviews.llvm.org/D118840
2022-02-07[ELF] Clean up headers. NFCFangrui Song1-2/+1
2022-01-20Re-land [LLD] Remove global state in lldCommonAlexandre Ganea1-4/+4
Move all variables at file-scope or function-static-scope into a hosting structure (lld::CommonLinkerContext) that lives at lldMain()-scope. Drivers will inherit from this structure and add their own global state, in the same way as for the existing COFFLinkerContext. See discussion in https://lists.llvm.org/pipermail/llvm-dev/2021-June/151184.html The previous land f860fe362282ed69b9d4503a20e5d20b9a041189 caused issues in https://lab.llvm.org/buildbot/#/builders/123/builds/8383, fixed by 22ee510dac9440a74b2e5b3fe3ff13ccdbf55af3. Differential Revision: https://reviews.llvm.org/D108850
2022-01-16Revert [LLD] Remove global state in lldCommonAlexandre Ganea1-4/+4
It seems to be causing issues on https://lab.llvm.org/buildbot/#/builders/123/builds/8383
2022-01-16[LLD] Remove global state in lldCommonAlexandre Ganea1-4/+4
Move all variables at file-scope or function-static-scope into a hosting structure (lld::CommonLinkerContext) that lives at lldMain()-scope. Drivers will inherit from this structure and add their own global state, in the same way as for the existing COFFLinkerContext. See discussion in https://lists.llvm.org/pipermail/llvm-dev/2021-June/151184.html Differential Revision: https://reviews.llvm.org/D108850
2021-12-26[ELF] ScriptParser: change std::vector to SmallVectorFangrui Song1-23/+23
2021-12-26[ELF] LinkerScript/OutputSection: change other std::vector members to ↵Fangrui Song1-4/+4
SmallVector 11+KiB smaller .text with both libc++ and libstdc++ builds.
2021-11-25[ELF] Rename BaseCommand to SectionCommand. NFCFangrui Song1-8/+8
BaseCommand was picked when PHDRS/INSERT/etc were not implemented. Rename it to SectionCommand to match `sectionCommands` and make it clear that the commands are used in SECTIONS (except a special case for SymbolAssignment). Also, improve naming of some BaseCommand variables (base -> cmd).
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