libthr: allow very early atfork registration

LSan wants to be able to register atfork handlers at __lsan_init time,
which can happen either at the first intercepted function call or in a
.preinit_ar

libthr: allow very early atfork registration

LSan wants to be able to register atfork handlers at __lsan_init time,
which can happen either at the first intercepted function call or in a
.preinit_array function. Both of these end up being very early in rtld
and executed with the bind lock held, which ends up causing problems
when we go to _libpthread_init().

Instead of requiring libpthread to be initialized, just insert the new
atfork handler straight into the list if it's not ready yet. The
critical section and locking should not be necessary if we're really
executing this early, as there won't be any threads to contend with.

Reviewed by: kib (earlier version), markj
Differential Revision: https://reviews.freebsd.org/D47349

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libthr: remove explicit sys/cdefs.h includes

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

libthr rtld locks: do not leak URWLOCK_READ_WAITERS into child

Since there is only the current thread in the child, no pending readers
exist. Clear the bit, since it confuses future attempts to acq

libthr rtld locks: do not leak URWLOCK_READ_WAITERS into child

Since there is only the current thread in the child, no pending readers
exist. Clear the bit, since it confuses future attempts to acquire
write ownership of the rtld locks, due to URWLOCK_PREFER_READERS flag.

To be future-proof, clear all state about pending writers and readers.

PR: 271490
Reported and tested by: KJ Tsanaktsidis <kj@kjtsanaktsidis.id.au>
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D40178

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libthr: wrap pdfork(2), same as fork(2).

Without wrapping, rtld services and malloc(3) are not guaranteed
to operate correctly in the forked child.

Reviewed by: markj
MFC after: 1 week
Sponsored by

libthr: wrap pdfork(2), same as fork(2).

Without wrapping, rtld services and malloc(3) are not guaranteed
to operate correctly in the forked child.

Reviewed by: markj
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D28088

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Avoid conflicts with libc symbols in libthr jump table.

In some corner cases of static linking and unexpected libraries order
on the linker command line, libc symbol might preempt the same libthr
sy

Avoid conflicts with libc symbols in libthr jump table.

In some corner cases of static linking and unexpected libraries order
on the linker command line, libc symbol might preempt the same libthr
symbol, in which case libthr jump table points back to libc causing
either infinite recursion or loop. Handle all of such symbols by
using private libthr names for them, ensuring that the right pointers
are installed into the table.

In collaboration with: arichardson
PR: 239475
Tested by: pho
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D21088

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Merge ^/head r343320 through r343570.

Untangle jemalloc and mutexes initialization.

The need to use libc malloc(3) from some places in libthr always
caused issues. For instance, per-thread key allocation was switched to
use plain mmap(

Untangle jemalloc and mutexes initialization.

The need to use libc malloc(3) from some places in libthr always
caused issues. For instance, per-thread key allocation was switched to
use plain mmap(2) to get storage, because some third party mallocs
used keys for implementation of calloc(3).

Even more important, libthr calls calloc(3) during initialization of
pthread mutexes, and jemalloc uses pthread mutexes. Jemalloc provides
some way to both postpone the initialization, and to make
initialization to use specialized allocator, but this is very fragile
and often breaks. See the referenced PR for another example.

Add the small malloc implementation used by rtld, to libthr. Use it in
thr_spec.c and for mutexes initialization. This avoids the issues with
mutual dependencies between malloc and libthr in principle. The
drawback is that some more allocations are not interceptable for
alternate malloc implementations. There should be not too much memory
use from this allocator, and the alternative, direct use of mmap(2) is
obviously worse.

PR: 235211
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D18988

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Merge ^/head r340918 through r341763.

Use _thr_isthreaded() and _thr_setthreaded() wrappers

...instead of directly using the global variable.

MFC after: 2 weeks
Sponsored by: Dell EMC Isilon

Merge ^/head r325999 through r326131.

General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier f

General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

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MFH

Sponsored by: The FreeBSD Foundation

Use __FBSDID() for .c files from lib/libthr/thread.

Sponsored by: The FreeBSD Foundation

MFH

Sponsored by: The FreeBSD Foundation

Lock pshared_lock shared around fork, to ensure that the COW snapshot
of the pshared hash in child is consistent and can be safely used.

Reported and tested by: "Oleg V. Nauman" <oleg@opentransfer.c

Lock pshared_lock shared around fork, to ensure that the COW snapshot
of the pshared hash in child is consistent and can be safely used.

Reported and tested by: "Oleg V. Nauman" <oleg@opentransfer.com>
Sponsored by: The FreeBSD Foundation

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MFH r289384-r293170

Sponsored by: The FreeBSD Foundation

Mfh r292839

Typo.

Merge sync of head

MFhead @ r277403

Reintegrate head: r274132-r277384

Sponsored by: The FreeBSD Foundation

Reintegrate head revisions r273096-r277147

Sponsored by: The FreeBSD Foundation

Fix known issues which blow up the process after dlopen("libthr.so")
(or loading a dso linked to libthr.so into process which was not
linked against threading library).

- Remove libthr interposers o

Fix known issues which blow up the process after dlopen("libthr.so")
(or loading a dso linked to libthr.so into process which was not
linked against threading library).

- Remove libthr interposers of the libc functions, including
__error(). Instead, functions calls are indirected through the
interposing table, similar to how pthread stubs in libc are already
done. Libc by default points either to syscall trampolines or to
existing libc implementations. On libthr load, libthr rewrites the
pointers to the cancellable implementations already in libthr. The
interposition table is separate from pthreads stubs indirection
table to not pull pthreads stubs into static binaries.

- Postpone the malloc(3) internal mutexes initialization until libthr
is loaded. This avoids recursion between calloc(3) and static
pthread_mutex_t initialization.

- Reinstall signal handlers with wrapper on libthr load. The
_rtld_is_dlopened(3) is used to avoid useless calls to sigaction(2)
when libthr is statically referenced from the main binary.

In the process, fix openat(2), swapcontext(2) and setcontext(2)
interposing. The libc symbols were exported at different versions
than libthr interposers. Export both libc and libthr versions from
libc now, with default set to the higher version from libthr.

Remove unused and disconnected swapcontext(3) userspace implementation
from libc/gen.

No objections from: deischen
Tested by: pho, antoine (exp-run) (previous versions)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

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Merge head from 7/28