Remove unused code that's confusing when using cscope/opengrok.

When _SOFT_FLOAT is defined, don't save or restore user FP context.
(note: still needs some mk rules tweaking for MKSOFTFLOAT=yes to pass
-msoft-float to asm builds).

Remove a comment made obsolete by the previous commit.

branches: 1.3.4;
Don't need to set the MSR field here; _INITCONTEXT_U_MD() takes care
of that where necessary.

Merge the nathanw_sa branch.

branches: 1.1.2;
file _context_u.S was initially added on branch nathanw_sa.

Remove unused code that's confusing when using cscope/opengrok.

Remove the PTHREAD_SA option. If M:N threads is reimplemented it's
better off done with a seperate library.

Remove possible race condition in upcall recycling.

Adapt to structure name changes.

Remove PT_SLEEPUC and add PT_TRAPUC.

Add _REG_foo to ppc mcontext and use them instead of constants.

Merge the nathanw_sa branch.

branches: 1.1.2;
file genassym.cf was initially added on branch nathanw_sa.

Revert previous:
http://mail-index.netbsd.org/source-changes/2020/02/20/msg114173.html

Comment turned out to be wrong, and KASSERT fires for oea.

XXX
Need to revisit shortly...

libpthread sets initial value of MSR for lwp's. However, appropriate
value differs b/w oea/booke/ibm4xx, and there's no way to obtain it
from userland. Therefore, this initial value should be corrected by
cpu_setmcontext().

- Comment this in libpthread
- Add KASSERT in cpu_mcontext_validate()

branches: 1.7.44; 1.7.46;
make pthread__sp unsigned long.

branches: 1.6.2;
Remove unused code that's confusing when using cscope/opengrok.

Remove leading __ from __(const|inline|signed|volatile) -- it is obsolete.

Add ucontext conversion macros for an "extra" register set.

Add _REG_foo to ppc mcontext and use them instead of constants.

Merge the nathanw_sa branch.

branches: 1.1.2;
file pthread_md.h was initially added on branch nathanw_sa.

Remove the PTHREAD_SA option. If M:N threads is reimplemented it's
better off done with a seperate library.

remove unreferenced temporary label

Fix a comment to say "Edit" instead of "Exit".

Remove possible race condition in upcall recycling.

Adapt to pt_trapuc: change STACK_SWITCH to check for a value in pt_trapuc
and use it preferentially to a value in pt_uc, clearing it once on the new
stack. Move stores into pt_uc back to before the stack switch; storing
after the stack switch opened a one-instruction race condition where an upcall
that had just started a chain could be preempted again, and would bomb when
restarted due to its pt_uc not yet having been updated. Now that pt_trapuc
is what the upcall code writes to, it is safe to store to pt_uc before
switching stacks.

Remove obsolete pt_sleepuc code.

Oops, reordering the PT_STATE/PT_SWITCHTOUC/PT_SWITCHTO assembly
killed a live value too soon. Fix by using a different register for
the PT_STATE immediate.

Update the switch_return point name in the static case.

Two fixes:
* In switch-away cases, write PT_SWITCHTO last (after PT_SWITCHTOUC), so
that pthread__resolve_locks() doesn't see an empty SWITCHTOUC value. This
also permits pthread__resolve_locks() to use the presence of PT_SWITCHTO
as a sign that the thread has done all of its necessary chain work.

* Make the return-point of pthread__switch global and visible, so that its
address can be compared to the PC of a thread, again as a sign that its
chain-work is done.

(other architectures in progress, after they get the *previous* asm fix...)

Fix typo in comment.

Merge the nathanw_sa branch.

branches: 1.1.2;
file pthread_switch.S was initially added on branch nathanw_sa.