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    SubjectRe: Re: [RFC PATCH 4/6] uprobes/x86: Emulate rip-relative call's
    On Fri, Apr 11, 2014 at 5:03 AM, Masami Hiramatsu
    <masami.hiramatsu.pt@hitachi.com> wrote:
    > At least, if we can trust Intel SDM, it says that depends
    > on the operand-size (insn->opnd_bytes) and stack segment
    > descriptor. Please check the SDM vol.1 6.2.2 Stack Alignment
    > and vol.2a, 3.2 Instructions (A-M), CALL--Call Procedure.
    > But we'd better check it on x86-32.

    I am past trusting CPU manuals on this one:

    By now I verified on the real hardware that AMD and Intel CPUs
    handle this insn differently in 64-bit mode: Intel ignores 0x66 prefix.
    AMD treats this insn the same as in 32-bit mode: as 16-bit insn.

    (Should I submit a patch adding comment about it
    in x86-opcode-map.txt?)

    So there is no universally "correct" way to emulate it.

    We, theoretically, can decode it differently *depending
    on actual CPU(s) on the system*... do we really want
    to go *that* far? I guess not.

    --
    vda


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