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    SubjectRe: [PATCH?] uprobes: change uprobe_write_opcode() to modify the page directly
    On 12/04/2013 08:48 AM, Oleg Nesterov wrote:
    > On 12/04, H. Peter Anvin wrote:
    >>
    >> On 12/04/2013 03:11 AM, Oleg Nesterov wrote:
    >>>
    >>> It is still not clear to me if we can simply change a single byte on
    >>> x86 or not, but at least on powerpc we need to update 4 bytes. Perhaps
    >>> we can conditionalize these pte games later.
    >>>
    >>
    >> But 4 aligned bytes can be written as a single transaction.
    >
    > Ah yes, this is true.
    >

    That is why I talk about the atomic instruction word... most (but not
    *all*) architectures have a fundamental minimum unit of instructions
    which is aligned and can be atomically written. Typically this is 1, 2,
    or 4 bytes.

    -hpa



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