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    SubjectRe: [PATCH RFC 3/4] x86/pti: don't mark the user PGD with _PAGE_NX.
    On Mon, Jan 08, 2018 at 09:23:49AM -0800, Dave Hansen wrote:
    > On 01/08/2018 09:17 AM, Willy Tarreau wrote:
    > >> I think the prctl() should apply to an entire process, not to a thread.
    > >
    > > As I mentionned in another mail, I didn't know how to do it, even less
    > > how to do it fast enough so that we didn't add more cycles to the syscall
    > > code.
    >
    > You can _implement_ it with a task thread if you want. Just spray it
    > across all threads at the prctl()-time instead of a single thread.
    > It'll take a wee bit of locking.
    >
    > I just don't think the API should apply to a single thread.

    It is surprisingly hard to find all tasks that share an mm. Finding all
    threads in a threadgroup is easy, but we have CLONE_THREAD and CLONE_VM
    as separate bits.

    In any case, aside from that, setting this remotely is indeed
    'intersting'.

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