x32 processes, with CONFIG_X86_X32 not set

From: Dave Jones
Date: Fri Mar 25 2016 - 11:48:45 EST

I had a trinity process get stuck last overnight.
The reason for it getting stuck is my bug (I think), but
there's an odd unrelated thing I noticed while debugging this..

$ strace -p 20966
strace: Process 20966 attached
strace: [ Process PID=20966 runs in x32 mode. ]

So I don't use that new-fangled x32 stuff.
I don't even have CONFIG_X86_X32 compiled in.

Is this strace getting confused, or did we somehow screw
up the syscall entry code ?