The R_MIPS_GPREL16 / R_MIPS_GPREL32 relocations use the following
expressions for calculations:
```
local symbol: S + A + GP0 - GP
global symbol: S + A - GP
GP - Represents the final gp value, i.e. _gp symbol
GP0 - Represents the gp value used to create the relocatable object
```
The GP0 value is taken from the .reginfo data section defined by an object
file. To implement that I keep a reference to `MipsReginfoInputSection`
in the `ObjectFile` class. This reference is used by the
`ObjectFile::getMipsGp0` method to return the GP0 value.
Differential Revision: http://reviews.llvm.org/D15760
llvm-svn: 256416
The file crtbeginT.o has relocations pointing to the start of an empty
.eh_frame that is known to be the first in the link. It does that to
identify the start of the output .eh_frame. Handle this special case.
Differential revision: http://reviews.llvm.org/D15610
llvm-svn: 256414
In FreeBSD, rtld expects .ctors containing -1 (0xffffffff), and a
.ctors section containing the correct bits is provided to the linker as
input (/usr/lib/crtbegin.o).
Contents of section .ctors:
0000 ffffffff ffffffff ........
This section is not stripped even if not referenced or empty, also in
gold or ld.bfd. It would be nice to strip it when not needed but
since existing object files rely on that we can't do better to keep it
around.
Differential Revision: http://reviews.llvm.org/D15767
llvm-svn: 256373
Before this patch sections that go after relro sequence were placed at
the same memory page with relro ones. It caused segmentation fault on
freebsd.
Fixes PR25790.
Patch by George Rimar with some tweaks by myself.
llvm-svn: 256334
The patch adds support for R_MIPS_PC16, R_MIPS_PC19_S2, R_MIPS_PC21_S2,
R_MIPS_PC26_S2, R_MIPS_PCHI16, R_MIPS_PCLO16 relocations handling.
llvm-svn: 256172
This patch changes sequence of applying relocations, moving tls optimized relocation handling code before code for other locals.
Without that change relocation @GOTTPOFF against local symbol caused runtime error ("unrecognized reloc ...").
That change also should fix other tls optimized relocations, but I did not check them, that's a field for another patch.
R_X86_64_GOTTPOFF relocations against locals can be found when linking against libc.a(malloc.o):
000000000036 000600000016 R_X86_64_GOTTPOFF 0000000000000000 libc_tsd_MALLOC - 4
000000000131 000600000016 R_X86_64_GOTTPOFF 0000000000000000 libc_tsd_MALLOC - 4
Differential revision: http://reviews.llvm.org/D15581
llvm-svn: 256145
This relocation is similar to R_*_RELATIVE except that the value used in this relocation is the program address returned by the function, which takes no arguments, at the address of
the result of the corresponding R_*_RELATIVE relocation as specified in the processor-specific ABI. The purpose of this relocation to avoid name lookup for locally defined STT_GNU_IFUNC symbols at load-time.
More info can be found in ifunc.txt from https://sites.google.com/site/x32abi/documents.
Differential revision: http://reviews.llvm.org/D15235
llvm-svn: 256144
R_386_GOTOFF is calculated as S + A - GOT, where:
S - Represents the value of the symbol whose index resides in the relocation entry.
A - Represents the addend used to compute the value of the relocatable field.
GOT - Represents the address of the global offset table.
Differential revision: http://reviews.llvm.org/D15383
llvm-svn: 256143
MIPS .reginfo section provides information on the registers used by
the code in the object file. Linker should collect this information and
write .reginfo section in the output file. This section contains a union
of used registers masks taken from input .reginfo sections and final
value of the `_gp` symbol.
For details see the "Register Information" section in Chapter 4 in the
following document:
ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
The patch implements .reginfo sections handling with a couple missed
features: a) it does not put output .reginfo section into the separate
REGINFO segment; b) it does not merge `ri_cprmask` masks from input
section. These features will be implemented later.
Differential Revision: http://reviews.llvm.org/D15669
llvm-svn: 256119
The patch configure ELF header flags for MIPS target. For now the flags
are hard coded. In fact they depends on ELF flags of input object files
and selected emulation.
Differential Revision: http://reviews.llvm.org/D15575
llvm-svn: 256089
The assembly at the top of this file contained more relocations than
the YAML. I regenerated it so that we'd have complete relocation testing.
Also added detailed explanations of the relocations in the file so that
future people don't have to try decode them when something goes wrong.
llvm-svn: 256064
@indntpoff is similar to @gotntpoff, but for use in position dependent code. While @gotntpoff resolves to GOT slot address relative to the
start of the GOT in the movl or addl instructions, @indntpoff resolves to the
absolute GOT slot address. ("ELF Handling For Thread-Local Storage", Ulrich Drepper).
Differential revision: http://reviews.llvm.org/D15494
llvm-svn: 255884
negDelta32 is only ever implicitly generated as the FDE->CIE reference.
We therefore don't emit a relocation for it in the object file in -r mode.
The value we write in to the FDE location therefore needs to point to the
final target address of the CIE, and not the inAtomAddress as it was currently
doing.
llvm-svn: 255835
The `_gp_disp` is a magic symbol designates offset between start of
function and gp pointer into GOT. Only `R_MIPS_HI16` and `R_MIPS_LO16`
relocations are permitted with `_gp_disp`. The patch adds the `_gp_disp`
as an ignored symbol and adjusts symbol value before call the `relocateOne`
for `R_MIPS_HI16/LO16` relocations.
Differential Revision: http://reviews.llvm.org/D15480
llvm-svn: 255768
The `R_MIPS_JALR` is a relocation generated by gcc and gas. This
relocation points to the `jalr` instruction which might be optimized and
converted to the `b` instruction under some conditions.
Now we just ignore this relocation and keep instructions unchanged.
llvm-svn: 255453
If we don't filter these out we can end up, generating bogus paths, for example:
/home/user/lld/build/bin -> /home/user/home/user/lld/build/bin/lld/build/bin.
llvm-svn: 255378
It is reasonable to specify an entry point for shared objects - for
example, for the FreeBSD rtld ld-elf.so.1.
Unlike GNU ld we leave the entry address as 0 if -shared is specified
without -e.
Differential Revision: http://reviews.llvm.org/D15454
llvm-svn: 255349
R_X86_64_SIZE64/R_X86_64_SIZE32 relocations were introduced in 0.98v of "System V Application Binary Interface x86-64" (http://www.x86-64.org/documentation/abi.pdf).
Calculation for them is Z + A, where:
Z - Represents the size of the symbol whose index resides in the relocation entry.
A - Represents the addend used to compute the value of the relocatable field.
Differential revision: http://reviews.llvm.org/D15335
llvm-svn: 255332
When llvm-lit prints a failure, you'll see something like 'lld *command*' However, you can't then take this, paste it in to a terminal and run it, because it's not got the absolute path of lld.
llvm and clang's lit.cfg files contain lists of commands to look for which are substituted by their full paths. So now you'd see something like '*build dir*/bin/lld *command*'.
This patch adds the same capability to lld's lit.cfg
Reviewed by Rafael Espíndola
llvm-svn: 255283
The delta64 relocation is represented as the pair ARM64_RELOC_SUBTRACTOR and ARM64_RELOC_UNSIGNED.
Those should always have the same offset, so this adds a check and tests to ensure this is the case.
Also updated the error printing in this case to shows both relocs when erroring on pair.
llvm-svn: 255274
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
If R_386_PLT32 relocation is applied against symbol that can not be preempted then it can be resolved statically.
Patch implements it for x86 target.
Differential revision: http://reviews.llvm.org/D15376
llvm-svn: 255233
Implement the TLS relocation optimization for 32-bit x86 that is described in
"ELF Handling For Thread-Local Storage" by Ulrich Drepper, chapter 5,
"IA-32 Linker Optimizations". Specifically, this patch implements these
optimizations: LD->LE, GD->IE, GD->LD, and IE->LE.
Differential revision: http://reviews.llvm.org/D15292
llvm-svn: 255103
The gcc_except_tab was generating these references to point to the typeinfo in the data section.
gcc_except_tab also had the DW_EH_PE_indirect flag set which means that at runtime we are going
to dereference this entry as if it is in the GOT.
Reviewed by Nick Kledzik in http://reviews.llvm.org/D15360.
llvm-svn: 255085
All relocations, which cannot be handled by the dynamic linker,
cause a linking error "rebuild with -fPIC".
Differential revision: http://reviews.llvm.org/D15193
llvm-svn: 254840
"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
If a section symbol is not external, that COMDAT section should never
be merge with other sections in other compilation unit. Previously,
we didn't take visibility into account.
Note that COMDAT sections with non-external visibility makes sense
because they can be removed by dead-stripping.
Fixes https://llvm.org/bugs/show_bug.cgi?id=25686
llvm-svn: 254578
Main aim of the patch to introduce basic support for TLS access models for x86 target.
Models using @tlsgd, @tlsldm and @gotntpoff are implemented.
Differential revision: http://reviews.llvm.org/D15060
llvm-svn: 254500
Some MIPS relocations including `R_MIPS_HI16/R_MIPS_LO16` use combined
addends. Such addend is calculated using addends of both paired relocations.
Each `R_MIPS_HI16` relocation is paired with the next `R_MIPS_LO16`
relocation. ABI requires to compute such combined addend in case of REL
relocation record format only.
For details see p. 4-17 at
ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
This patch implements lookup of the next paired relocation suing new
`InputSectionBase::findPairedRelocLocation` method. The primary
disadvantage of this approach is that we put MIPS specific logic into
the common code. The next disadvantage is that we lookup `R_MIPS_LO16`
for each `R_MIPS_HI16` relocation, while in fact multiple `R_MIPS_HI16`
might be paired with the single `R_MIPS_LO16`. From the other side
this way allows us to keep `MipsTargetInfo` class stateless and implement
later relocation handling in parallel.
This patch does not support `R_MIPS_HI16/R_MIPS_LO16` relocations against
`_gp_disp` symbol. In that case the relocations use a special formula for
the calculation. That will be implemented later.
Differential Revision: http://reviews.llvm.org/D15112
llvm-svn: 254461
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
ABI specifies the allowed range for these relocations as 2^(n-1) <= X < 2^n.
The patch fixes checks and introduces precise tests for these relocations.
Differential revision: http://reviews.llvm.org/D14957
llvm-svn: 254146
In case a sysroot prefix is configured, and the filename starts with
the '/' character, and the script being processed was located inside
the sysroot prefix, the file's name will be looked for in the sysroot
prefix. Otherwise, the linker falls to the common lookup scheme.
It is slightly modified version of the commit r254031. The problem of
the initial commit was in the `is_absolute` call. On Windows 'C:\' is
absolute path but we do not need to find it under sysroot. In this patch
linker looks up a path under sysroot only if the paths starts with '/'
character.
llvm-svn: 254135
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
Patch implements lazy relocations for x86.
One of features of x86 is that executable files and shared object files have separate procedure linkage tables. So patch implements both cases.
Detailed information about instructions used can be found in http://docs.oracle.com/cd/E19620-01/805-3050/chapter6-1235/index.html (search: x86: Procedure Linkage Table).
Differential revision: http://reviews.llvm.org/D14955
llvm-svn: 254098
R_MIPS_CALL16 relocation provides the same result as R_MIPS_GOT16
relocation but does not need to check the result on overflow.
Differential Revision: http://reviews.llvm.org/D14916
llvm-svn: 254092
Simon Atanasyan