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
relocateOne is a function to apply a relocation. Previously, that
function took a pointer to Elf_Rel or Elf_Rela in addition to other
information that can be derived from the relocation entry. This patch
simplifies the parameter list. The new parameters, P or SA, are used
in the ELF spec to describe each relocation. These names make
relocateOne look like a mechanical, direct translation of the ELF spec.
llvm-svn: 251090
These classes are partially written, so almost all features
are FIXMEs. We do not want to add new FIXMEs to the classes
when we add new features to other non-stub classes.
llvm-svn: 250947
Target has supportsLazyRelocations() method which can switch lazy relocations on/off (currently all targets are OFF except x64 which is ON). So no any other targets are affected now.
Differential Revision: http://reviews.llvm.org/D13856?id=37726
llvm-svn: 250808
Instead of specifically creating .plt entries for weak undef symbols, mirror
the logic in r250584, and use canBePreempted to determine is a REL24 relocation
needs a .plt entry. This might cause relocateOne to be called for a weak undef
symbol, with a REL24 relocation, but ignore this as a special case (this will
cause SA == 0, which won't happen under any other circumstance).
llvm-svn: 250597
There is sometimes no need to generate relocation via PLT.
Example - when symbol is not undefined and we are not creating shared library. Then we can create relative relocation instead of referencing and creating PLT records.
Differential Revision: http://reviews.llvm.org/D13835
llvm-svn: 250584
R_PPC64_TOC does not have an associated symbol, but does have a non-zero VA
that target-specific code must compute using some non-trivial rule. We
handled this as a special case in PPC64TargetInfo::relocateOne, where
we knew to write this special address, but that did not work when creating shared
libraries. The special TOC address needs to be the subject of a
R_PPC64_RELATIVE relocation, and so we also need to know how to encode this
special address in the addend of that relocation.
Thus, some target-specific logic is necessary when creating R_PPC64_RELATIVE as
well. To solve this problem, we teach getLocalRelTarget to handle R_PPC64_TOC
as a special case. This allows us to remove the special case in
PPC64TargetInfo::relocateOne (simplifying code there), and naturally allows the
existing logic to do the right thing when creating associated R_PPC64_RELATIVE
relocations for shared libraries.
llvm-svn: 250555
When I initially implemented PPC64TargetInfo::isRelRelative, I included a fixed
set of relative relocations, and made the default false. In retrospect, this
seems unwise in two respects: First, most PPC64 relocations are relative
(either to the base address, the TOC, etc.). Second, most relocation targets
are not appropriate for R_PPC64_RELATIVE (which writes a 64-bit absolute
address). Thus, back off, and include only those relocations for which we test
(or soon will), and are obviously appropriate for R_PPC64_RELATIVE.
llvm-svn: 250540
Unfortunately, the check was not as dead as I had thought, and adjusting the
starting VA again exposed the problem. We end up trying to relocate the bl
(using a 24-bit relative offset) to a symbol address of zero, and in general,
that does not fit.
Thus, reverting for now, and adding a test case.
llvm-svn: 250423
When a relocation points to a SHF_MERGE section, the addend has special meaning.
It should be used to find what in the section the relocation points to. It
should not be added to the output position.
Centralizing it means that the above rule will be implemented once, not once
per target.
llvm-svn: 250421
After some additional post-commit (post-revert) discussion and research, this
reverts, in part, r250205, so the ABI-recommended starting address can be used
on PPC64 (as is done by other linkers).
Also, this addresses the FIXME in ELF/Writer.cpp by making VAStart a
target-dependent property.
llvm-svn: 250378
- Make the `MipsTargetInfo` template class with `ELFType` argument. Use
the argument to select an appropriate relocation type and read/write
routines.
- Add template function `add32` to add-and-write relocation value in
both big and little endian cases. Keep the `add32le` to reduce code
changes.
Differential Revision: http://reviews.llvm.org/D13723
llvm-svn: 250297
This has turned out to be unnecessary, and while some ability to set VAStart
will be needed at some point, this is not clearly the right direction.
llvm-svn: 250205
What was done:
1) .got.plt section is created for functions that requires PLT. .got.plt has 3 predefined empty entries now that are required for dynamic linker.
Also other new items created are configured to have correct jump to PLT[N].
2) PLT section now has PLT[0] entry, also others ones are configured to support PLT->GOT(.got.plt) calls.
3) Implemented .rel[a].plt sections (based on patch http://reviews.llvm.org/D13569).
4) Fixed plt relocations types (based on patch http://reviews.llvm.org/D13589).
NOTES:
The .plt.got zero entry is still empty now. According to ELF specification it should hold the address of the dynamic structure, referenced with the symbol
_DYNAMIC. The _DYNAMIC entry points to the .dynamic section which contains information used by the ELF interpreter to setup the binary.
Differential Revision: http://reviews.llvm.org/D13651
llvm-svn: 250169
Now all Target<Arch> classes are used only in Target.cpp.
We can put them in an anonymous namespace. In order to avoid
merge conflict with other people's patches, I'll do that later.
llvm-svn: 250168
Under PPC64 ELF v1 ABI, the symbols associated with each function name don't
point directly to the code in the .text section (or similar), but rather to a
function descriptor structure in a special data section named .opd. The
elements in the .opd structure include a pointer to the actual code, and a the
relevant TOC base value. Both of these are themselves set by relocations.
When we have a local call, we need the relevant relocation to refer directly to
the target code, not to the function-descriptor in the .opd section. Only when
we have a .plt stub do we care about the address of the .opd function
descriptor itself.
So we make a few changes here:
1. Always write .opd first, so that its relocated data values are available
for later use when writing the text sections. Record a pointer to the .opd
structure, and its corresponding buffer.
2. When processing a relative branch relocation under ppc64, if the
destination points into the .opd section, read the code pointer out of the
function descriptor structure and use that instead.
This this, I can link, and run, a dynamically-compiled "hello world"
application on big-Endian PPC64/Linux (ELF v1 ABI) using lld.
llvm-svn: 250122
