On Mon, Jan 27, 2014 at 4:22 PM, H. Peter Anvin <h...@zytor.com> wrote: > On 01/27/2014 02:46 PM, Andy Lutomirski wrote: >> >> I think that sysret for sigreturn is probably not very interesting. >> On the other hand, sysret for #PF might be a huge win, despite being >> even scarier. >> > > SYSRET for #PF or other exceptions is a nonstarter; register state is > live at that point.
I mean sysret-via-trampoline for #PF. It's scary, it probably has issues with ptrace and interrupts that hit while the trampoline is still running, and it could break anything that writes past the red zone, but I think it could work. No, I don't particularly want to implement (and debug) such a beast. (I will continue cursing Intel -- why can't we have a fast way to return to 64-bit userspace with complete control of all non-segment registers? sysret is *almost* the right thing.) --Andy > > -hpa > > -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
