Messages in this thread | | | Date | Sun, 17 Dec 2017 00:46:31 +0100 | From | Ingo Molnar <> | Subject | Re: [RFC GIT PULL] x86 Page Table Isolation (PTI) syscall entry code preparatory patches |
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Fri, Dec 15, 2017 at 5:58 PM, Ingo Molnar <mingo@kernel.org> wrote: > > > > These are the x86-64 low level entry code preparatory patches for the page table > > isolation patches - which are required for PTI, which addresses KASLR and similar > > information leaks. > > Ugh. > > Ok, I've read through this, and while I like most of it (I do like the > percpu syscall stack), I have this urge to wait until after rc4. With > the suspend/resume issues,
Yeah, so as a response to those breakages I recently started testing s2ram as a regular part of -tip testing, so every tree I send to you does s2ram fine on my (suspendable) testsystems. That's still not full coverage, but should be better than what we had.
> [...] we've had a horrible track record for 4.15 rc's so far, I'l like to not > pull another low-level x86 change just before an rc release and potentially make > it four for four broken rc's.
Yeah, I can understand that. I knew the weekend timing is awkward, but I tried to post it as soon as I felt it was ready and as soon upstream (x86) stability looked good.
> And I absolutely detest how that cherry-pick branch was done. I can > see why, but: > > - now we have those extra cherry-picks that I already have > > - and the merge commit isn't even a no-op! > > Dammit, if the point was to have a branch that worked for 4.14, I can > see that. But look at that merge (on the "other side"), and notice how > the end result is *not* identical to the parent. > > IOW, that > > 9a818d1a3235 Merge branch 'WIP.x86/pti.base' into x86/pti, to pick > up cherry-picked base tree and preparatory patches > > 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.
Thanks,
Ingo
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