On Fri, Apr 10, 2015 at 1:22 PM, Andi Kleen <[email protected]> wrote: > > > >> I think that your __switch_to is buggy and that's why the selectors >> need to be zero. Is that the only issue? If so, let's fix the bug >> instead. > > I don't think there is a bug.
So what's the issue? If user code programs fs != 0 and fsbase != whatever is implied by fs and the GDT/LDT, what happens? There's already a minor buglet in that area without wrfsbase, but fixing it would be a big performance hit because we don't have rdfsbase and rdgsbase to read the state efficiently. (Specifically, if we have gs == 0, gsbase == 0, but *saved* gsbase != 0, then we corrupt gsbase on context switch.) But, with the new instructions, we can do it simply, efficiently, and correctly in all cases. Let's do so. --Andy > > -Andi > > -- > [email protected] -- Speaking for myself only -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
