Messages in this thread |  | | Date | Wed, 04 Dec 2013 08:54:31 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH?] uprobes: change uprobe_write_opcode() to modify the page directly |
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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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