Re: [patch] i386: remove IOPL check on task switch

Andi Kleen
2006-11-04T20:02:25Z

> Ok, checking shows Linus put it back to stop NT leakage.

It is also needed to stop AC leakage

> This is
> correct, but unlikely. Would be nice to avoid it unless absolutely
> necessary. Perhaps xor eflags old and new and only set_system_eflags()
> if non-ALU bits have changed.

If it's worth it...

If it's worth for the context switch i think it would make
more sense to do it for the normal restore_flags() etc. which are much
more common (and could be actually handled in most cases with test + jump + sti)

-Andi