The real question is if we care that sysret and iter don't match. On 32 bits the situation is even more complex.
On June 26, 2014 1:00:22 PM PDT, Andy Lutomirski <[email protected]> wrote: >On Thu, Jun 26, 2014 at 12:59 PM, Andy Lutomirski <[email protected]> >wrote: >> On Thu, Jun 26, 2014 at 12:56 PM, Andi Kleen <[email protected]> >wrote: >>>> show RCX == RIP even under strace. >>> >>> If you think it's really worth the extra instruction? >> >> Hard to say. That extra instruction only happens on slow paths, so I >> suspect the slowdown is negligible. On the other hand, having >syscall >> show a blatant difference in behavior between traced and untraced >> processes seems unfortunate. >> >>> >>> It's not wrong, but it's not clear if it's useful. > >Also, if anyone ever wants to add some code to switch back from iret >to sysret when sysret will work, this is a prerequisite. Otherwise >sysret will never match iret. (I'm not immediately planning on doing >this, but I can imagine workloads (e.g. UML) for which it would be a >big improvement.) > >--Andy -- Sent from my mobile phone. Please pardon brevity and lack of formatting. -- 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/
