# Re: \[PATCH\] x86/paravirt: use %rip-relative addressing in hook calls

- From: Juergen Gross via Virtualization \<hidden\>
- Date: 2022-01-10 13:26:28 
- List: virtualization
- Page: https://ratatoskr.run/virtualization/2022/01/15818655
- Thread: https://ratatoskr.run/virtualization/2021/09/15818264/t.md

```text
On 23.11.21 10:52, Juergen Gross via Virtualization wrote:
> On 23.11.21 10:29, Jan Beulich wrote:
>> On 05.10.2021 09:43, Juergen Gross wrote:
>>> On 30.09.21 14:40, Jan Beulich via Virtualization wrote:
>>>> While using a plain (constant) address works, its use needlessly invokes
>>>> a SIB addressing mode, making every call site one byte larger than
>>>> necessary. Instead of using an "i" constraint with address-of operator
>>>> and a 'c' operand modifier, simply use an ordinary "m" constraint, which
>>>> the 64-bit compiler will translate to %rip-relative addressing. This way
>>>> we also tell the compiler the truth about operand usage - the memory
>>>> location gets actually read, after all.
>>>>
>>>> 32-bit code generation is unaffected by the change.
>>>>
>>>> Signed-off-by: Jan Beulich <redacted>
>>>
>>> Reviewed-by: Juergen Gross <jgross@suse.com>
>>
>> Thanks. I notice this wasn't part of your 5.16-rc1 pull request, nor
>> did it make it into Linus'es tree via any other route. May I ask what
>> the plans here are?
>
> I CC-ed you on the related mail I sent to the x86 maintainers:
>
> "Re: Which tree for paravirt related patches?" on Nov 4th, and Thomas
> Gleixner promised to look at your patch. Adding him to this response
> again in order to remind him.

Thomas, another ping. Didn't you want to take this patch more than a
month ago? Cc-ing the other x86 maintainers, too.


Juergen
```