[Bug 53682] wineboot shows "user_check_not_lock BUG: holding USER lock" on aarch64 since wine-7.14

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=53682

--- Comment #17 from Kevin Puetz  ---
> there's a slight risk of clobbering the stack below sp at that point I believe

Yeah, I see no indications that wine uses sigaltstack outside of wineserver, so
there's at least the chance of an ill-timed signal coming in and smashing
things up if sp is *ever* pointed at syscall_frame rather than the actual
top-of-stack. If signals use the normal stack, you can't just use sp as scratch
register even in asm that will eventually put it back.