lkml.org 
[lkml]   [2018]   [Jan]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v3 3/3] x86/retpoline: Convert generic specific retpolines to use RETPOLINE_GENERIC
    Date
    From
    On Wed, 2018-01-10 at 08:23 -0600, Tom Lendacky wrote:
    > On 1/10/2018 7:15 AM, Woodhouse, David wrote:
    > > On Tue, 2018-01-09 at 18:28 -0800, Andi Kleen wrote:
    > >> From: Andi Kleen <ak@linux.intel.com>
    > >>
    > >> X86_FEATURE_RETPOLINE has been renamed to X86_FEATURE_RETPOLINE_GENERIC.
    > >> Convert the sequences using it.
    > > 
    > > AMD documentation says they need the RSB fill too, so these should stay
    > > under X86_FEATURE_RETPOLINE I think.
    >
    > AMD processors don't fall back to the indirect predictor on an underflow
    > so this isn't needed on AMD if it is purely for underflow prevention.

    It isn't purely for underflow protection. This is needed (see the AMD
    doc) for protecting against RSB entries that actually point to
    userspace addresses. It's only not needed if we have SMEP.[unhandled content-type:application/x-pkcs7-signature]
    \
     
     \ /
      Last update: 2018-01-14 23:21    [W:4.216 / U:0.108 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site