Re: [BUG] x86 : i486 reporting to be vulnerable to Meltdown/Spectre_V1/Spectre_V2

[tedheadster]

On Tue, Feb 6, 2018 at 2:24 PM, tedheadster <tedheadster@xxxxxxxxx> wrote:
> On Tue, Feb 6, 2018 at 2:17 PM, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
>> On Tue, 2018-02-06 at 11:13 -0800, Guenter Roeck wrote:
>>> On Tue, Feb 06, 2018 at 07:10:27PM +0000, David Woodhouse wrote:
>>> >
>>> >
>>> >
>>> > On Tue, 2018-02-06 at 11:02 -0800, Greg Kroah-Hartman wrote:
>>> > >
>>> > > .
>>> > > >
>>> > > >
>>> > > > David
>>> > > >    I believe I got the patch(es) you mention in in the stable 4.15.1 kernel:
>>> > > >
>>> > > > Pull x86/pti updates from Thomas Gleixner: "Another set of melted
>>> > > > spectrum related changes"
>>> > > > (commit 6304672b7f0a5c010002e63a075160856dc4f88d).
>>> > > >
>>> > > > Unfortunately, the symptoms I reported remain on at least the i486 and i686.
>>> > > Can you try 4.15.2-rc1?  Or how about Linus's kernel tree now?  There
>>> > > was a lot of spectrum patches merged just this week that were not in
>>> > > 4.15.1.
>>> > No, for the 486 it *should* have worked. The interesting commit
>>> > is fec9434a12 ("x86/pti: Do not enable PTI on CPUs which are not
>>> > vulnerable to Meltdown") which is indeed pulled in with the merge
>>> > commit that Matthew mentions.
>>> >
>>> I disagree.
>>>
>>> $ git describe
>>> v4.15.1-61-g7ab5513e4cbc
>>> $ git log --oneline v4.15.1.. | grep Melt
>>> 3472b3689bab x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
>>
>> Ah right, for 4.15.1 perhaps yes. I was looking at Matthew's 'commit
>> 6304672b7f0a5c010002e63a075160856dc4f88d' which isn't in 4.15.1 at all;
>> that's the commit in Linus' tree where he pulled in the fix. So *that*
>> one should have had it.
>

Okay, I did a 'git pull' from Linus' tree and rebuilt. I _believe_ I
have the correct patches from this information:

localhost /usr/src/linux # git log | grep "Do not enable PTI on CPUs
which are not vulnerable to Meltdown"
    Fixes: fec9434a12f3 ("x86/pti: Do not enable PTI on CPUs which are
not vulnerable to Meltdown")
      x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
    x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown

localhost /usr/src/linux # git log | grep -A8
6304672b7f0a5c010002e63a075160856dc4f88d
commit 6304672b7f0a5c010002e63a075160856dc4f88d
Merge: 942633523cde 64e16720ea08
Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date:   Mon Jan 29 19:08:02 2018 -0800

    Merge branch 'x86-pti-for-linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

    Pull x86/pti updates from Thomas Gleixner:
     "Another set of melted spectrum related changes:


If that is correct (and I might be wrong), then I am up to date and I
am still getting the following in /proc/cpuinfo on my Pentium 4M i686:

bugs  : cpu_meltdown spectre_v1 spectre_v2

- Matthew