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    SubjectRe: [PATCH v4 10/10] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule
    [Sorry, possible resend.]

    On 5/31/11, Ingo Molnar <> wrote:
    > * Ingo Molnar <> wrote:
    >> [...] solution that filters the caller RIP at the generic syscall
    >> entry point and checks RCX against the 'expected' SYSCALL
    >> instruction address, which is the (per task) vdso-address +
    >> constant-offset.
    > Note that this solution would allow the vsyscall page to be
    > 'filtered' to the 3 allowed system calls rather efficiently, via a
    > second level check.
    > This second check does not affect the fastpath, and it could be put
    > behind a CONFIG_COMPAT_VSYSCALL deprecation define once glibc does
    > not put vsyscall references anywhere - but we could even keep it
    > around forever, as this way it's defanged permanently.

    Are you thinking about the 32-bit vDSO? I think that 64-bit code puts
    syscalls instructions all over the place.

    How is this better than v2 of my series, stopping after the int cc fallback?


    > Thanks,
    > Ingo

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