[lkml]   [2008]   [May]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [RFC] x86: xsave/xrstor support, ucontext_t extensions
    H. Peter Anvin wrote:
    > Andi Kleen wrote:
    >>> Ok. CPU folks are planning to make some of the bytes at the end of
    >>> fxsave
    >>> image, SW usable.
    >> Are they always zeroed in earlier CPUs though? If not that wouldn't
    >> work 100% reliably because whatever cookie you put in could have been
    >> there before by chance.
    >> I don't see anything in the SDM guaranteeing zeroing.
    > I'm pretty sure they weren't zeroed by the CPUs. If they weren't zeroed
    > *by the kernel*, there might have been an information leak.

    I don't think there is one. We never copy fxsave completely out of the
    kernel. x86-64 does FXSAVE directly in/out user space, but the
    only leak is what there was before.


     \ /
      Last update: 2008-05-20 17:07    [W:0.021 / U:0.168 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site