Re: [PATCH 5.15 00/78] 5.15.55-rc1 review

Paolo Bonzini
2022-07-15T11:35:32Z

On 7/14/22 20:16, Linus Torvalds wrote:
> Oh, btw, how bad would it be to just do
>
> #define FASTOP_SIZE 16
> static_assert(FASTOP_SIZE >= FASTOP_LENGTH)

Yeah, for 32 I might have some (probably irrational) qualms, but 16 is
not worth the trouble.

Given 3 bytes for ENDBR, 5 for the return thunk and 1 for the straight
line speculation INT3, there are 7 bytes left and only 4 are currently
used (for instructions encoded as "66 0f xx xx"). So FASTOP_SIZE at
SETCC_ALIGN can indeed be 16 unconditionally.

Paolo