Previously, OffsetInBSS is -1 if it has no information about copy
relocation, 0 if it needs a copy relocation, and >0 if its offset
in BSS has been assigned. These flags were too subtle. This patch
adds a new flag, NeedsCopy, to carry information about whether
a shared symbol needs a copy relocation or not.
llvm-svn: 255865
The function was used only in Writer.cpp and did not depend on SymbolTable.
There is no reason to have that function in SymbolTable.cpp.
llvm-svn: 255850
List all sections removed by garbage collection. This option is only effective if garbage collection has been enabled via the `--gc-sections' option.
Differential revision: http://reviews.llvm.org/D15327
llvm-svn: 255235
"Ulrich Drepper, ELF Handling For Thread-Local Storage" (5.5 x86-x64 linker optimizations, http://www.akkadia.org/drepper/tls.pdf) shows how GD can be optimized to IE.
This patch implements the optimization.
Differential revision: http://reviews.llvm.org/D15000
llvm-svn: 254713
Combination of @tlsgd and @gottpoff at the same time leads to miss of R_X86_64_TPOFF64 dynamic relocation. Patch fixes that.
@tlsgd(%rip) - Allocate two contiguous entries in the GOT to hold a tls index
structure (for passing to tls get addr).
@gottpoff(%rip) - Allocate one GOT entry to hold a variable offset in initial TLS
block (relative to TLS block end, %fs:0).
The same situation can be observed for x86 (probably others too, not sure) with corresponding for that target relocations: @tlsgd, @gotntpoff.
Differential revision: http://reviews.llvm.org/D15105
llvm-svn: 254443
Fix was:
uint32_t getLocalTlsIndexVA() { return getVA() + LocalTlsIndexOff; }
=>
uint32_t getLocalTlsIndexVA() { return Base::getVA() + LocalTlsIndexOff; }
Both works for my MSVS.
Original commit message:
[ELF] - Refactor of tls_index implementation for tls local dynamic model.
Patch contains the next 2 changes:
1) static variable Out<ELFT>::LocalModuleTlsIndexOffset moved to Out<ELFT>::Got. At fact there is no meaning for it to be separated from GOT class because at each place of using it anyways needs to call GOT`s getVA(). Also it is impossible to have that offset and not have GOT.
2) addLocalModuleTlsIndex -> addLocalModelTlsIndex (word "Module" changed to "Model"). Not sure was it a mistype or not but I think that update is closer to Urlich terminology.
Differential revision: http://reviews.llvm.org/D15113
llvm-svn: 254433
It failed buildbot:
http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/3782/steps/build/logs/stdio
Target.cpp
In file included from /home/buildbot/Buildbot/Slave/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/llvm.src/tools/lld/ELF/Target.cpp:20:
/home/buildbot/Buildbot/Slave/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/llvm.src/tools/lld/ELF/OutputSections.h:136:42: error: use of undeclared identifier 'getVA'
uint32_t getLocalTlsIndexVA() { return getVA() + LocalTlsIndexOff; }
llvm-svn: 254432
Patch contains the next 2 changes:
1) static variable Out<ELFT>::LocalModuleTlsIndexOffset moved to Out<ELFT>::Got. At fact there is no meaning for it to be separated from GOT class because at each place of using it anyways needs to call GOT`s getVA(). Also it is impossible to have that offset and not have GOT.
2) addLocalModuleTlsIndex -> addLocalModelTlsIndex (word "Module" changed to "Model"). Not sure was it a mistype or not but I think that update is closer to Urlich terminology.
Differential revision: http://reviews.llvm.org/D15113
llvm-svn: 254428
Implements @tlsld (LD to LE) and @tlsgd (GD to LE) optimizations.
Patch does not implement the GD->IE case for @tlsgd.
Differential revision: http://reviews.llvm.org/D14870
llvm-svn: 254101
This patch implements next relocations:
R_386_TLS_LE - Negative offset relative to static TLS (GNU version).
R_386_TLS_LE_32 - Offset relative to static TLS block.
These ones are created when using next code sequences:
* @tpoff - The operator must be used to compute an immediate value. The linker will report
an error if the referenced variable is not defined or it is not code for the executable
itself. No GOT entry is created in this case.
* @ntpoff Calculate the negative offset of the variable it is added to relative to the static TLS block.
The operator must be used to compute an immediate value. The linker will report
an error if the referenced variable is not defined or it is not code for the executable
itself. No GOT entry is created in this case.
Information was found in Ulrich Drepper, ELF Handling For Thread-Local Storage, http://www.akkadia.org/drepper/tls.pdf, (6.2, p76)
Differential revision: http://reviews.llvm.org/D14930
llvm-svn: 254090
In the previous patch (r254003), I made the linker emit PT_GNU_STACK
unconditionally. But sometimes you want to have a control over the
presence of the segment. With this patch, you can omit the segment
by passing -z execstack option.
llvm-svn: 254039
Partial (-z relro) and full (-z relro, -z now) relro cases are implemented.
Partial relro:
The ELF sections are reordered so that the ELF internal data sections (.got, .dtors, etc.) precede the program's data sections (.data and .bss).
.got is readonly, .got.plt is still writeable.
Full relro:
Supports all the features of partial RELRO, .got.plt is also readonly.
Differential revision: http://reviews.llvm.org/D14218
llvm-svn: 253967
With this patch, lld creates PT_GNU_STACK segments only when all input
files have .note.GNU-stack sections. This is in line with other linkers
with a minor difference (we don't care about .note.GNU-stack rwx bits as
you can always remove .note.GNU-stack sections instead of setting x bit.)
At least, NetBSD loader does not understand PT_GNU_STACK segments and
reject any executables that have the section. This patch makes lld
compatible with such operating systems.
llvm-svn: 253797
PT_GNU_STACK is a entry in the elf file format which contains the access rights (read, write, execute) of the stack,
it is always generated now. By default stack is not executable in this implementation.
-z execstack can be used to make executable.
Differential revision: http://reviews.llvm.org/D14571
llvm-svn: 253145
This sections can be protected with relro after resolving relocations by dynamic linker.
Differential revision: http://reviews.llvm.org/D14567
llvm-svn: 253018
The MIPS target requires specific dynamic section entries to be defined.
* DT_MIPS_RLD_VERSION and DT_MIPS_FLAGS store predefined values.
* DT_MIPS_BASE_ADDRESS holds base VA.
* DT_MIPS_LOCAL_GOTNO holds the number of local GOT entries.
* DT_MIPS_SYMTABNO holds the number of .dynsym entries.
* DT_MIPS_GOTSYM holds the index of the .dynsym entry
which corresponds to the first entry of the global part of GOT.
* DT_MIPS_RLD_MAP holds the address of the reserved space in the data segment.
* DT_MIPS_PLTGOT points to the .got.plt section if it exists.
* DT_PLTGOT holds the address of the GOT section.
See "Dynamic Section" in Chapter 5 in the following document for detailed
description: ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
Differential revision: http://reviews.llvm.org/D14450
llvm-svn: 252857
This adds support for:
* Uniquing CIEs
* Dropping FDEs that point to dropped sections
It drops 657 488 bytes from the .eh_frame of a Release+Asserts clang.
The link time impact is smallish. Linking clang with a Release+Asserts
lld goes from 0.488064805 seconds to 0.504763060 seconds (1.034 X slower).
llvm-svn: 252790
GNU as can give it type SHT_PROGBITS or SHT_X86_64_UNWIND depending on
teh construct.
MC gives it type SHT_X86_64_UNWIND.
The linker has to canonicalize to one or the other so that there is only
one .eh_frame in the end.
llvm-svn: 252757
leaq symbol@tlsld(%rip), %rdi
call __tls_get_addr@plt
symbol@tlsld (R_X86_64_TLSLD) instructs the linker to generate a tls_index entry (two GOT slots) in the GOT for the entire module (shared object or executable) with an offset of 0. The symbol for this GOT entry doesn't matter (as long as it's either local to the module or null), and gold doesn't put a symbol in the dynamic R_X86_64_DTPMOD64 relocation for the GOT entry.
All other platforms defined in http://www.akkadia.org/drepper/tls.pdf except for Itanium use a similar model where global and local dynamic GOT entries take up 2 contiguous GOT slots, so we can handle this in a unified manner if we don't care about Itanium.
While scanning relocations we need to identify local dynamic relocations and generate a single tls_index entry in the GOT for the module and store the address of it somewhere so we can later statically resolve the offset for R_X86_64_TLSLD relocations. We also need to generate a R_X86_64_DTPMOD64 relocation in the RelaDyn relocation section.
This implementation is a bit hacky. It side steps the issue of GotSection and RelocationSection only handling SymbolBody entries by relying on a specific relocation type. The alternative to this seemed to be completely rewriting how GotSection and RelocationSection work, or using a different hacky signaling method.
llvm-svn: 252682
This is cleaner than computing relocations as if we had done it.
While at it, keep a single Phdr variable instead of multiple fields of it.
llvm-svn: 252352
This patch implements R_MIPS_GOT16 relocation for global symbols in order to
generate some entries in GOT. Only reserved and global entries are supported
for now. For the detailed description about GOT in MIPS, see "Global Offset
Table" in Chapter 5 in the followin document:
ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
In addition, the platform specific symbol "_gp" is added, see "Global Data
Symbols" in Chapter 6 in the aforementioned document.
Differential revision: http://reviews.llvm.org/D14211
llvm-svn: 252275
For x86-64 the initial executable TLS block is placed directly before the
thread specific data register so compilers can directly access it via
R_X86_64_TPOFF32. Generate the correct (negative) offset for this case.
llvm-svn: 252131
This does not support TPOFF32 relocations to local symbols as the address calculations are separate. Support for this will be a separate patch.
llvm-svn: 251998
This is a case where there is inconsistency among ELF linkers:
* The spec says nothing special about empty sections.
* BFD ld removes them.
* Gold handles them like regular sections.
We were outputting them but sometimes ignoring them. This would create
odd looking outputs where a rw section could be in a ro segment for example.
The bfd way of doing things is also strange for the case where a symbol
points to the empty section.
Now we match gold and what seems to be the intention of the spec.
llvm-svn: 251988
Rui Ueyama