sanitizers: mark __elf_aux_vector as weak, to allow linking without libsys

After libsys was introduced, linking sanitized programs started failing
with:

# c++ -fsanitize=address main.cc
ld: error: undefined symbol: __elf_aux_vector
>>> referenced by sanitizer_linux_libcdep.cpp:950 (/usr/src/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp:950)
>>> sanitizer_linux_libcdep.o:(__sanitizer::ReExec()) in archive /usr/lib/clang/17/lib/freebsd/libclang_rt.asan-x86_64.a
c++: error: linker command failed with exit code 1 (use -v to see invocation)

Mark __elf_aux_vector as weak in the internal sanitizer declaration, so
the linker will accept it at link time. The dynamic linker will then
take care of the symbol at run time.

Suggestion by: brooks
PR: 276104, 277393
MFC after: 1 month

Merge llvm-project main llvmorg-18-init-16003-gfc5f51cf5af4

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-16003-gfc5f51cf5af4.

PR: 276104
MFC after: 1 month

Merge llvm-project main llvmorg-18-init-15088-gd14ee76181fb

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-15088-gd14ee76181fb.

PR: 276104
MFC after: 1 month

Merge llvm-project main llvmorg-17-init-19304-gd0b54bb50e51

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-17-init-19304-gd0b54bb50e51, the
last commit before the upstream release/17.x branch was created.

PR: 273753
MFC after: 1 month

compiler-rt: remove unnecessary include

This is to sync the code with upstream, see:
See https://github.com/llvm/llvm-project/pull/73439#discussion_r1406644942

Fixes: 4c9a0adad182
MFC after: 3 days

compiler-rt: avoid segfaults when re-exec'ing with ASLR

After 930a7c2ac67e ("compiler-rt: re-exec with ASLR disabled when
necessary") and 96fe7c8ab0f6 ("compiler-rt: support ReExec() on
FreeBSD"), binaries linked against the sanitizer libraries may segfault
due to procctl(2) being intercepted. Instead, the non-intercepted
internal_procctl() should be called.

Similarly, the ReExec() function that re-executes the binary after
turning off ASLR should not call elf_aux_info(3) and realpath(3), since
these will also be intercepted. Instead, loop directly over the elf aux
info vector to find the executable path, and avoid calling realpath(3)
since it is actually unwanted for this use case.

Fixes: 930a7c2ac67e, 96fe7c8ab0f6
MFC after: 3 days

Merge llvm-project release/16.x llvmorg-16.0.1-0-gcd89023f7979

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16.0.1-0-gcd89023f7979 (aka 16.0.1 release).

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-16-init-18548-gb0daacf58f41

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16-init-18548-gb0daacf58f41.

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-15-init-17485-ga3e38b4a206b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-17485-ga3e38b4a206b.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-15-init-15358-g53dc0f10787

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-15358-g53dc0f10787.

PR: 265425
MFC after: 2 weeks

Merge llvm-project release/14.x llvmorg-14.0.0-rc1-74-g4dc3cb8e3255

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14.0.0-rc1-74-g4dc3cb8e3255.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-17616-g024a1fab5c35

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-17616-g024a1fab5c35.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-13186-g0c553cc1af2e

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-13186-g0c553cc1af2e.

PR: 261742
MFC after: 2 weeks

compiler-rt: support ReExec() on FreeBSD

Based on getMainExecutable() in llvm/lib/Support/Unix/Path.inc.
This will need a little more work for an upstream change as it must
support older FreeBSD releases that lack elf_aux_info() / AT_EXEC_PATH.

No objection: dim
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33934

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/compiler-rt/dist up to its last change, and resolve conflicts.

Merge llvm-project main llvmorg-17-init-19304-gd0b54bb50e51

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-17-init-19304-gd0b54bb50e51, the
last commit before the upstream release/17.x branch was created.

PR: 273753
MFC after: 1 month

compiler-rt: remove unnecessary include

This is to sync the code with upstream, see:
See https://github.com/llvm/llvm-project/pull/73439#discussion_r1406644942

Fixes: 4c9a0adad182
MFC after: 3 days

compiler-rt: avoid segfaults when re-exec'ing with ASLR

After 930a7c2ac67e ("compiler-rt: re-exec with ASLR disabled when
necessary") and 96fe7c8ab0f6 ("compiler-rt: support ReExec() on
FreeBSD"), binaries linked against the sanitizer libraries may segfault
due to procctl(2) being intercepted. Instead, the non-intercepted
internal_procctl() should be called.

Similarly, the ReExec() function that re-executes the binary after
turning off ASLR should not call elf_aux_info(3) and realpath(3), since
these will also be intercepted. Instead, loop directly over the elf aux
info vector to find the executable path, and avoid calling realpath(3)
since it is actually unwanted for this use case.

Fixes: 930a7c2ac67e, 96fe7c8ab0f6
MFC after: 3 days

Merge llvm-project release/16.x llvmorg-16.0.1-0-gcd89023f7979

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16.0.1-0-gcd89023f7979 (aka 16.0.1 release).

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-16-init-18548-gb0daacf58f41

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16-init-18548-gb0daacf58f41.

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-15-init-17485-ga3e38b4a206b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-17485-ga3e38b4a206b.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-15-init-15358-g53dc0f10787

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-15358-g53dc0f10787.

PR: 265425
MFC after: 2 weeks

Merge llvm-project release/14.x llvmorg-14.0.0-rc1-74-g4dc3cb8e3255

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14.0.0-rc1-74-g4dc3cb8e3255.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-17616-g024a1fab5c35

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-17616-g024a1fab5c35.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-13186-g0c553cc1af2e

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-13186-g0c553cc1af2e.

PR: 261742
MFC after: 2 weeks

compiler-rt: support ReExec() on FreeBSD

Based on getMainExecutable() in llvm/lib/Support/Unix/Path.inc.
This will need a little more work for an upstream change as it must
support older FreeBSD releases that lack elf_aux_info() / AT_EXEC_PATH.

No objection: dim
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33934

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/compiler-rt/dist up to its last change, and resolve conflicts.

compiler-rt: remove unnecessary include

This is to sync the code with upstream, see:
See https://github.com/llvm/llvm-project/pull/73439#discussion_r1406644942

Fixes: 4c9a0adad182
MFC after: 3 days

compiler-rt: avoid segfaults when re-exec'ing with ASLR

After 930a7c2ac67e ("compiler-rt: re-exec with ASLR disabled when
necessary") and 96fe7c8ab0f6 ("compiler-rt: support ReExec() on
FreeBSD"), binaries linked against the sanitizer libraries may segfault
due to procctl(2) being intercepted. Instead, the non-intercepted
internal_procctl() should be called.

Similarly, the ReExec() function that re-executes the binary after
turning off ASLR should not call elf_aux_info(3) and realpath(3), since
these will also be intercepted. Instead, loop directly over the elf aux
info vector to find the executable path, and avoid calling realpath(3)
since it is actually unwanted for this use case.

Fixes: 930a7c2ac67e, 96fe7c8ab0f6
MFC after: 3 days

Merge llvm-project release/16.x llvmorg-16.0.1-0-gcd89023f7979

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16.0.1-0-gcd89023f7979 (aka 16.0.1 release).

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-16-init-18548-gb0daacf58f41

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16-init-18548-gb0daacf58f41.

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-15-init-17485-ga3e38b4a206b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-17485-ga3e38b4a206b.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-15-init-15358-g53dc0f10787

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-15358-g53dc0f10787.

PR: 265425
MFC after: 2 weeks

Merge llvm-project release/14.x llvmorg-14.0.0-rc1-74-g4dc3cb8e3255

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14.0.0-rc1-74-g4dc3cb8e3255.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-17616-g024a1fab5c35

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-17616-g024a1fab5c35.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-13186-g0c553cc1af2e

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-13186-g0c553cc1af2e.

PR: 261742
MFC after: 2 weeks

compiler-rt: support ReExec() on FreeBSD

Based on getMainExecutable() in llvm/lib/Support/Unix/Path.inc.
This will need a little more work for an upstream change as it must
support older FreeBSD releases that lack elf_aux_info() / AT_EXEC_PATH.

No objection: dim
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33934

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/compiler-rt/dist up to its last change, and resolve conflicts.

Merge llvm-project main llvmorg-15-init-17485-ga3e38b4a206b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-17485-ga3e38b4a206b.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-15-init-15358-g53dc0f10787

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-15358-g53dc0f10787.

PR: 265425
MFC after: 2 weeks

Merge llvm-project release/14.x llvmorg-14.0.0-rc1-74-g4dc3cb8e3255

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14.0.0-rc1-74-g4dc3cb8e3255.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-17616-g024a1fab5c35

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-17616-g024a1fab5c35.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-13186-g0c553cc1af2e

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-13186-g0c553cc1af2e.

PR: 261742
MFC after: 2 weeks

compiler-rt: support ReExec() on FreeBSD

Based on getMainExecutable() in llvm/lib/Support/Unix/Path.inc.
This will need a little more work for an upstream change as it must
support older FreeBSD releases that lack elf_aux_info() / AT_EXEC_PATH.

No objection: dim
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33934

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/compiler-rt/dist up to its last change, and resolve conflicts.

Merge llvm-project release/14.x llvmorg-14.0.0-rc1-74-g4dc3cb8e3255

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14.0.0-rc1-74-g4dc3cb8e3255.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-17616-g024a1fab5c35

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-17616-g024a1fab5c35.

PR: 261742
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-13186-g0c553cc1af2e

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-13186-g0c553cc1af2e.

PR: 261742
MFC after: 2 weeks

compiler-rt: support ReExec() on FreeBSD

Based on getMainExecutable() in llvm/lib/Support/Unix/Path.inc.
This will need a little more work for an upstream change as it must
support older FreeBSD releases that lack elf_aux_info() / AT_EXEC_PATH.

No objection: dim
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33934

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/compiler-rt/dist up to its last change, and resolve conflicts.

compiler-rt: support ReExec() on FreeBSD

Based on getMainExecutable() in llvm/lib/Support/Unix/Path.inc.
This will need a little more work for an upstream change as it must
support older FreeBSD releases that lack elf_aux_info() / AT_EXEC_PATH.

No objection: dim
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33934

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/compiler-rt/dist up to its last change, and resolve conflicts.