Hi Andrew.

Attached patch works around the corruption
of the high word of the ESP register, which
is the official bug of x86 CPUs. The bug
triggers only when the one is using the
16bit stack segment.
Patch helps running many apps under dosemu,
and, according to the comments found in
Wine sources, also helps Wine.

The patch defines the per-CPU 16bit stacks,
and every time the process that uses 16bit
stack, returns to the userspace, we switch
to our 16bit stack and preload the high word
of ESP.
This also closes the "informational leak",
which is that the user process is not
supposed to know the kernel's ESP value.

Can this please be applied?

Acked-by: Linus Torvalds <torvalds@osdl.org>
|Signed-off-by: Stas Sergeev <stsp@aknet.ru>|