[PATCH 0/3] PTI for x86-32 Fixes and Updates

[Joerg Roedel <joro@8bytes.org>]

Hi,

here are 3 patches which update the PTI-x86-32 patches recently merged
into the tip-tree. The patches are ordered by importance:

	Patch 1: Very important, it fixes a vmalloc-fault in NMI context
		 when PTI is enabled. This is pretty unlikely to hit
		 when starting perf on an idle machine, which is why I
		 didn't find it earlier in my testing. I always started
		 'perf top' first :/ But when I start 'perf top' last
		 when the kernel-compile already runs, it hits almost
		 immediatly.

	Patch 2: Fix the 'from-kernel-check' in SWITCH_TO_KERNEL_STACK
	         to also take VM86 into account. This is not strictly
		 necessary because the slow-path also works for VM86
		 mode but it is not how the code was intended to work.
		 And it breaks when Patch 3 is applied on-top.

	Patch 3: Implement the reduced copying in the paranoid
		 entry/exit path as suggested by Andy Lutomirski while
		 reviewing version 7 of the original patches.

I have the x86/tip branch with these patches on-top running my test for
6h now, with no issues so far. So for now it looks like there are no
scheduling points or irq-enabled sections reached from the paranoid
entry/exit paths and we always return to the entry-stack we came from.

I keep the test running over the weekend at least.

Please review.

[ If Patch 1 looks good to the maintainers I suggest applying it soon,
  before too many linux-next testers run into this issue. It is actually
  the reason why I send out the patches _now_ and didn't wait until next
  week when the other two patches got more testing from my side. ]

Thanks,

	Joerg

Joerg Roedel (3):
  perf/core: Make sure the ring-buffer is mapped in all page-tables
  x86/entry/32: Check for VM86 mode in slow-path check
  x86/entry/32: Copy only ptregs on paranoid entry/exit path

 arch/x86/entry/entry_32.S   | 82 ++++++++++++++++++++++++++-------------------
 kernel/events/ring_buffer.c | 10 ++++++
 2 files changed, 58 insertions(+), 34 deletions(-)

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2.7.4