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    Subject[PATCH 0/3] PTI for x86-32 Fixes and Updates
    Date
    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(-)

    --
    2.7.4

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