The AArch64 unconditional branch and branch and link instructions have a
maximum range of 128 Mib. This is usually enough for most programs but
there are cases when it isn't enough. This change adds support for range
extension thunks to AArch64. For pc-relative thunks we follow the small
code model and use ADRP, ADD, BR. This has a limit of 4 gigabytes.
Differential Revision: https://reviews.llvm.org/D39744
llvm-svn: 319307
The SHT_ARM_ATTRIBUTES section type is in the processor specific space
adding guard to make sure that it is only recognized when EMachine is
EM_ARM.
llvm-svn: 319304
This includes a fix to mark copy reloc aliases as used.
Original message:
[ELF] Do not keep symbols if they referenced only from discarded sections.
This patch also ensures that in case of "--as-needed" is used,
DT_NEEDED entries are not created if they are required only by
these eliminated symbols.
llvm-svn: 319215
lld assumes some ARM features that are not available in all Arm
processors. In particular:
- The blx instruction present for interworking.
- The movt/movw instructions are used in Thunks.
- The J1=1 J2=1 encoding of branch immediates to improve Thumb wide
branch range are assumed to be present.
This patch reads the ARM Attributes section to check for the
architecture the object file was compiled with. If none of the objects
have an architecture that supports either of these features a warning
will be given. This is most likely to affect armv6 as used in the first
Raspberry Pi.
Differential Revision: https://reviews.llvm.org/D36823
llvm-svn: 319169
Currently we mark every shared symbol as STB_WEAK.
That is a hack to make it easy to decide when a .so is needed or not
because of a reference to a given symbol.
That hack leaks when we create copy relocations as shown by the update
to relocation-copy-alias.s.
This patch stores the original binding when we first read a shared
symbol. We still have to update the binding to weak if we see a weak
undef, but I find the logic easier to read where it is now.
llvm-svn: 319127
When an undefined weak reference has a PLT entry we must generate a range
extension thunk for any B or BL that can't reach the PLT entry.
This change explicitly looks for whether a PLT entry exists rather than
assuming that weak references never need PLT entries unless Config->Shared
is in operation. This covers the case where we are linking an executable
with dynamic linking, hence a PLT entry will be needed for undefined weak
references. This case comes up in real programs over 32 Mb in size as there
is a B to a weak reference __gmon__start__ in the Arm crti.o for glibc.
Differential Revision: https://reviews.llvm.org/D40248
llvm-svn: 319020
This patch also ensures that in case of "--as-needed" is used,
DT_NEEDED entries are not created if they are required only by
these eliminated symbols.
Differential Revision: https://reviews.llvm.org/D38790
llvm-svn: 319008
LLD uses .bss.rel.ro for read-only copy relocations whereas the ld.bfd and
gold linkers use .data.rel.ro. In some linker scripts including ld.bfd's
internal linker script, the relro sections are placed sequentially assuming
.data.rel.ro is used. LLD's use of .bss.rel.ro means that the copy
relocations get matched into the .bss section causing the relro sections to
be non-contiguous.
This change checks for a .data.rel.ro OutputSection when a linker script
with the SECTIONS command is used. The section will match in the
.data.rel.ro output section and will maintain contiguous relro.
Differential Revision: https://reviews.llvm.org/D40365
Fixes PR35265
llvm-svn: 318940
When checking for contiguous relro sections we can skip over empty sections.
If there is an empty non-relro section in the middle of a contiguous block
of relro sections then it cannot be written to so it is safe to include in
PT_GNU_RELRO header. If there is a contiguous block of empty relro sections
then no PT_GNU_RELRO header is required for them.
Differential Revision: https://reviews.llvm.org/D40364
llvm-svn: 318924
If a linker script is used that names linker generated synthetic sections
it is possible that the OutputSections for which isRelroSection() is true
are not contiguous. When the relro sections are not contiguous we cannot
describe them with a single PT_GNU_RELRO PHDR. Unfortunately at least one
contemporary dynamic loader only supports one PT_GNU_RELRO PHDR so we
cannot output more than one of these PHDRs. As not including relro
sections in the PHDR will lead to security sensitive sections being
writeable we choose to give an error message instead.
Differential Revision: https://reviews.llvm.org/D40359
[ELF] Skip over empty sections when checking for contiguous relro
llvm-svn: 318920
The MIPS GOT section has a number of local entries based on the number of pages
needed for output sections referenced by GOT page relocations. The number is
recorded in the DT_MIPS_LOCAL_GOTNO dynamic section tag. However, the dynamic tag
is added before assignAddresses has been called, meaning that any section size used
to calculate the value will not include size modifications caused by, for example,
linker scripts and thunks.
This change moves the calculation of DT_MIPS_LOCAL_GOTNO until writeTo, by which
time the output section sizes have been finalized.
Reviewers: ruiu, rafael
Differential Revision: https://reviews.llvm.org/D39493
llvm-svn: 318828
Summary:
I noticed that the reproducers files I was getting from building CheriBSD
didn't work because the --sysroot option was not being rewritten. I've
updated the test to also verify that the rewritten path matches uses a
FileCheck capature instead of a {{.+}} regex
Reviewers: ruiu
Reviewed By: ruiu
Subscribers: llvm-commits, emaste
Differential Revision: https://reviews.llvm.org/D40125
llvm-svn: 318656
Summary:
This matches the behaviour of ld.bfd:
https://sourceware.org/binutils/docs/ld/Options.html#Options
If scriptfile does not exist in the current directory, ld looks for it in
the directories specified by any preceding '-L' options. Multiple '-T'
options accumulate.
Reviewers: ruiu, grimar
Reviewed By: ruiu, grimar
Subscribers: emaste, llvm-commits
Differential Revision: https://reviews.llvm.org/D40129
llvm-svn: 318655
Summary:
The bug triggers when the following conditions are met:
- A thunk is created in a given input section S
- A linker script is specified
- There is at least one matcher in the linker script .text section output
that does not match any of the sections in the input files, before the matcher
that matches section S.
The issue was found when linking the FreeBSD kernel for MIPS when built
with -fPIC. Patch by Alfredo Mazzinghi.
Reviewers: ruiu, psmith, atanasyan
Reviewed By: ruiu
Subscribers: peter.smith, emaste, sdardis, krytarowski, llvm-commits
Differential Revision: https://reviews.llvm.org/D40174
llvm-svn: 318653
It is private to llvm. Instead use llvm/Config/llvm-config.h and check
LLVM_ON_UNIX. That is the same guard that clang uses before including
unistd.h.
llvm-svn: 318558
Recently we teached LLD to report line numbers for duplicate variables
definitions, though currently LLD is unable to do that for case when
strings are not built in .debug_info, but stored in .debug_str instead.
That is because out LLDDwarfObj does not handle .debug_str yet.
Patch fixes that.
Differential revision: https://reviews.llvm.org/D39542
llvm-svn: 318519
This fixes PR35223.
Here I enabled SHF_MERGE section content merging for -r like
we do for regular linking.
Differential revision: https://reviews.llvm.org/D40026
llvm-svn: 318516
Previously our relocations we rewrote were broken for that case.
We emited incorrect addend and broken relocation info field
because did not produce section symbol for mergeable synthetic sections.
Differential revision: https://reviews.llvm.org/D40070
llvm-svn: 318394
An output section can include elements from two input sections with
different sh_entsize. When that happens the output section itself
should not have a sh_entsize.
llvm-svn: 318311
No difference in practice other than having sh_entsize in the output.
This should simplify the patch for handling SHF_MERGE in -r.
Based on a patch by George Rimar.
llvm-svn: 318306
Rafael Espindola