Building binaries as PIE allows the executable itself to be loaded at a
random address when ASLR is enabled (not just its shared libraries).
With this change PIE objects have a .pieo extension and INTERNALLIB
libraries libXXX_pie.a.
MK_PIE is disabled for some kerberos5 tools, Clang, and Subversion, as
they explicitly reference .a libraries in their Makefiles. These can
be addressed on an individual basis later. MK_PIE is also disabled for
rtld-elf because it is already position-independent using bespoke
Makefile rules.
Currently only dynamically linked binaries will be built as PIE.
Discussed with: dim
Reviewed by: kib
MFC after: 1 month
Relnotes: Yes
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D18423
Some options come from static constructors in LLVM libraries and are
automatically added to llvm's usage output. They're not really supposed
to be llvm-objdump options.
Reported by: Fangrui Song in LLVM review D54864
Sponsored by: The FreeBSD Foundation
Some options appear in llvm-objdump's usage information as a side effect
of its option parsing implementation and are not actually llvm-objdump
options. Reported in LLVM review https://reviews.llvm.org/D54864.
Reported by: Fangrui Song
Sponsored by: The FreeBSD Foundation
Based on llvm-objdump's online documentation and usage information.
This serves as a starting point; additional detail and cleanup still
required.
Also being submitted upstream in LLVM review D54864. I expect to use
this bespoke copy while we have LLVM 6.0 or 7.0 in FreeBSD; when we
update to LLVM 8.0 it should be upstream and we will switch to it.
PR: 233437
Reviewed by: bcr (man formatting)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D18309
llvm-profdata is used with llvm-cov for code coverage (although llvm-cov
can also operate independently in a gcov-compatible mode).
Although llvm-profdata can be used independently of llvm-cov it makes
sense to group these under one option.
Also handle these in OptionalObsoleteFiles.inc while here.
Sponsored by: The FreeBSD Foundation
llvm-cov provides a gcov-compatible interface when invoked as gcov.
Reviewed by: dim, markj
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17923
The current kernel ifunc implementation creates a PLT entry for each
ifunc definition. ifunc calls therefore consist of a call to the
PLT entry followed by an indirect jump. The jump target is written
during boot when the kernel linker resolves R_[*]_IRELATIVE relocations.
This implementation is defined by requirements for userland code, where
text relocations are avoided. This requirement is not present for the
kernel, so the implementation has avoidable overhead (namely, an extra
indirect jump per call).
Address this for now by adding a special option to the static linker
to inhibit PLT creation for ifuncs. Instead, relocations to ifunc call
sites are passed through to the output file, so the kernel linker can
enumerate such call sites and apply PC-relative relocations directly
to the text section. Thus the overhead of an ifunc call becomes exactly
the same as that of an ordinary function call. This option is only for
use by the kernel and will not work for regular programs.
The final form of this optimization is up for debate; for now, this
change is simple and static enough to be acceptable as an interim
solution.
Reviewed by: emaste
Discussed with: arichardson, dim
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D16748
LLD_BOOTSTRAP (build) is independent of LLD_IS_LD (installed) so they
should not be based on each other.
This is related to upcoming WITH_SYSTEM_LINKER work.
Reviewed by: emaste
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D15836
Introduce WITH_/WITHOUT_LLVM_COV to match GCC's WITH_/WITHOUT_GCOV.
It is intended to provide a superset of the interface and functionality
of gcov.
It is enabled by default when building Clang, similarly to gcov and GCC.
This change moves one file in libllvm to be compiled unconditionally.
Previously it was included only when WITH_CLANG_EXTRAS was set, but the
complexity of a new special case for (CLANG_EXTRAS | LLVM_COV) is not
worth avoiding a tiny increase in build time.
Reviewed by: dim, imp
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D142645
Upstream lld has no man page. Introduce a basic one for FreeBSD based on
ld.lld --help, with a brief introduction and additional detail for some
options.
We'll continue refining this in FreeBSD, and then submit it upstream once
the first round of edits are complete.
Submitted by: krion, Arshan Khanifar, emaste, bjk
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D13813
- Include debug symbols in static libraries. This permits binaries
to include debug symbols for functions obtained from static libraries.
- Permit the C/C++ compiler flags added for MK_DEBUG_FILES to be
overridden by setting DEBUG_FILES_CFLAGS. Use this to limit the debug
information for llvm libraries and binaries.
Reviewed by: emaste
Sponsored by: DARPA / AFRL
Differential Revision: https://reviews.freebsd.org/D12025
