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    SubjectRe: [PATCH v8 3/8] seccomp: add system call filtering using BPF
    On 02/16/2012 06:16 PM, Andrew Lutomirski wrote:
    >
    > Is there really no syscall that cares about endianness?
    >
    > Even if it ends up working, forcing syscall arguments to have a
    > particular endianness seems like a bad decision, especially if anyone
    > ever wants to make a 64-bit BPF implementation. (Or if any
    > architecture adds 128-bit syscall arguments to a future syscall
    > namespace or whatever it's called. x86-64 has 128-bit xmm
    > registers...)
    >

    Not to mention that the reshuffling code will add totally unnecessary
    cost to the normal operation. Either way, Indan has it backwards ... it
    *is* one field, the fact that two operations is needed to access it is a
    function of the underlying byte code, and even if the byte code can't
    support it, a JIT could merge adjacent operations if 64-bit operations
    are possible -- or we could (and arguably should) add 64-bit opcodes in
    the future for efficiency.

    -hpa

    --
    H. Peter Anvin, Intel Open Source Technology Center
    I work for Intel. I don't speak on their behalf.



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