abort2: Generate a core dump

[jhb]

Summary

Call sigexit rather than exit1 so that a core is generated.

If running the SIGABRT handler is desired, this would need to use
kern_psignal() instead. In that case a userspace wrapper in libc
would be needed to force an exit if the handler doesn't exit. Given
that abort2(2)'s intended use case is when userland is in a
sufficiently bad state such that it can't safely call syslog(3) before
abort(3), a userspace abort2(3) wrapper in libc might be dubious.

[olce]

This change is a clear improvement (core dumped on SIGABRT), so IMHO should go in regardless of the "executing the SIGABRT handler" refinement.

sys/kern/kern_exit.c

831–832

sigexit() doesn't return (as exit1()), so the call to PROC_UNLOCK() is unnecesary, as well as the return.

I would remove them. I don't know for sure if there are still relevant compilers that would issue a warning or even an error about the function not containing a return statement at end, but I can say it's not a problem for clang 16.

[jhb]

Remove dead code

[emaste]

OK