linux-kernel - Re: [RFC GIT PULL] x86 Page Table Isolation (PTI) syscall entry code preparatory patches

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Message-ID: <20171217150220.nmgyvkbrkgvsu3zp@gmail.com>
Date:   Sun, 17 Dec 2017 16:02:21 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC GIT PULL] x86 Page Table Isolation (PTI) syscall entry code
 preparatory patches


* Ingo Molnar <mingo@...nel.org> wrote:

> > was supposed to be a synchronization point, but if you do
> > 
> >     git diff 9a818d1a3235..9a818d1a3235^
> > 
> > it isn't actually synchronized. It's *almost* synchronized, but not
> > quite. How did those cherry-picks that were already upstream end up
> > causing *changes* upstream? That's odd.
> > 
> > So there are some technical oddities in there.
> 
> Indeed, and I tried to make it a no-op merge, and it's _almost_ a no-op merge, 
> except these two commits:
> 
> One of the PTI namespace preparatory patches ended up in the 'base' tree:
> 
>   d78b637b29a2: drivers/misc/intel/pti: Rename the header file to free up the namespace
> 
> plus there's this cherry-pick from a very recent upstream kernel:
> 
>   c3bc8b53d54c: bpf: fix build issues on um due to mising bpf_perf_event.h
> 
> which was required for UML to build and be testable.
> 
> We can move both commits to a later stage in the tree to make the v4.14 base tree 
> an 'obvious' upstream-identical tree.
> 
> Will respin it all tomorrow.

So today I've respun it all, and I think it all got cleaner. I'm going to send you 
3 pull requests:

1) a 'preparatory tree' that is a single commit that frees up the PTI namespace

2) the 'v4.14 backport base tree' which is fully synchronized an should be a no-op 
   merge on your side. I also organized it a bit better with all cherry-picks in a 
   single linear range of commits, with clear notations.

3) the 'per CPU syscall tree', which will be a clean, linear series of commits 
   with no merge distractions whatsoever.

The first two you could pull today, with very low risk levels.

Thanks,

	Ingo