link_elf_obj: Invoke fini callbacks

[markj]

Summary

This is required for KASAN: when a module is unloaded, poisoned regions
(e.g., pad areas between global variables) are left as such, so if they
are reused as KLDs are loaded, false positives can arise.

Reported by: pho
Sponsored by: The FreeBSD Foundation

[kib]

Is the same handling needed for link_elf.c?

[markj]

In D31339#706113, @kib wrote:

Is the same handling needed for link_elf.c?

Yes, I just didn't do it since I don't have a good way to test yet. I did not implement .init_array support there yet either. I'll revisit this for link_elf when KASAN is ported to arm64, if that's ok with you.

[kib]

In D31339#706279, @markj wrote:

In D31339#706113, @kib wrote:

Is the same handling needed for link_elf.c?

Yes, I just didn't do it since I don't have a good way to test yet. I did not implement .init_array support there yet either. I'll revisit this for link_elf when KASAN is ported to arm64, if that's ok with you.

Sure I do not consider doing it for link_elf.c right now as a requirement.