On 2026-06-28 21:43, Matthew Wilcox wrote:
> On Sun, Jun 28, 2026 at 07:09:37PM -0700, H. Peter Anvin wrote:
>>
>>> 2) `enter` is not rare since we can take part in the instruction.
>>
>> This sentence doesn't parse.
>
> They mean that we can jump into the middle of an instruction, and it is
> not rare to see a 'c8' byte in the instruction stream.
>
OK, I see the point now. The main difference is that ENTER doesn't require a
REX prefix, whereas ADD/SUB/LEA do (otherwise it truncates RSP and everything
immediately dies as a result of SMAP violations [you are welcome].)
This means that an offending bit combination is far less common.
-hpa
