https://bugs.winehq.org/show_bug.cgi?id=51996
--- Comment #3 from Jinoh Kang jinoh.kang.kr@gmail.com --- (In reply to Zebediah Figura from comment #2)
(In reply to Jinoh Kang from comment #1)
IMHO a dedicated signal handler on SIGUSR2 to restore full context (used in NtContinue etc.) seems excessive to me. Is there any state on AArch64 that cannot be restored in user mode and may only be modified kernel side?
Yes. As far as we're aware, it's impossible to restore the *whole* context simultaneously, without using privileged instructions like ERET. You need to scratch a register to set the instruction pointer.
Thank you for explaining. Looks like it, and also the stack pointer. Thankfully FPU has nothing to do with this.
Any chance we would be using sigreturn() directly, though? On select known platforms with stable syscall ABI, of course.