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

From: Ingo Molnar
Date: Sun Dec 17 2017 - 10:02:32 EST

* Ingo Molnar <mingo@xxxxxxxxxx> 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.