so does thread cancelation works? according to Linux arch/arm64/kernel/vdso/sugreturn.s comments it should not,
as 'gdb, libgcc and libunwind rely on being able to identify the sigreturn instruction sequence to unwind from signal handler'
also see comment about misterious nop instruction. really weird piece of Linux

on all other Linuxulators I do not use sv_sigcode_base,
but I see that we can do some here, e.g. sv_sigcode is not used anymore so we do not need to initialize it and so..
I propose to do it as everywhere in Linuxulator, then make the same changes everywhere so that there is no need to test separately. ugh..

Turns out I can fail even at copy/pasting :-D

Should be fixed now.

Tbh we could just drop both sv_sigcode_base and sv_sigcode; we don't need them, do we?

yes, Linuxulator does not uses it, but sysctl_kern_proc_sigtramp() uses, I think what we can fix here

signo should be converted to the Linux signo

siginfo too, by siginfo_to_lsiginfo()