[PATCH v2 1/5] gpu: nova-core: use checked arithmetic in FWSEC firmware parsing

[Joel Fernandes]

On 1/28/2026 7:36 PM, Alexandre Courbot wrote:
> On Thu Jan 29, 2026 at 9:20 AM JST, Danilo Krummrich wrote:
>> On Wed Jan 28, 2026 at 4:14 PM CET, Joel Fernandes wrote:
>>> On 1/28/2026 5:53 AM, Danilo Krummrich wrote:
>>>> On Mon Jan 26, 2026 at 9:23 PM CET, Joel Fernandes wrote:
>>>>> @@ -267,7 +264,12 @@ fn new_fwsec(dev: &Device<device::Bound>, bios: &Vbios, cmd: FwsecCommand) -> Re
>>>>>           let ucode = bios.fwsec_image().ucode(&desc)?;
>>>>>           let mut dma_object = DmaObject::from_data(dev, ucode)?;
>>>>>   
>>>>> -        let hdr_offset = usize::from_safe_cast(desc.imem_load_size() + desc.interface_offset());
>>>>> +        // Compute hdr_offset = imem_load_size + interface_offset.
>>>>
>>>> I do get the idea behind those comments, but are we sure that's really a good
>>>> idea? How do we ensure to keep them up to date in case we have to change the
>>>> code?
>>>>
>>>> If we really want this, I'd at least chose a common syntax, e.g.
>>>>
>>>> 	// CALC: `imem_load_size + interface_offset`
>>>>
>>>> without the variable name the resulting value is assigned to.
>>>>
>>>> But I'd rather prefer to just drop those comments.
>>> The idea of adding these comments was to improve readability. However, I 
>>> can drop them in the v3, that's fine with me.
>>
>> Yeah, that's why I wrote "I get the idea". :) But as I write above, I'm
>> concerned about the comments getting outdated or inconsistent over time.
>>
>> Besides that, it more seems like something your favorite editor should help with
>> instead.
>>
>>> Do you want me to wait for additional comments on this series, or should 
>>> I make the update and repost it?  Thanks,
>>
>> As mentioned, I tend to think we should just drop them, but I'm happy to hear
>> some more opinions on this if any.
> 
> For safety I would keep something like the 
> 
>   // CALC: `imem_load_size + interface_offset`
> 
> you suggested. From simple operations yes, the code would be obvious,
> but there are also more involved computations where order matters and it
> is good to have a reference. These shouldn't change often anyway, and
> the `CALC:` header catches the attention of anyone who would update
> them, similarly to a `SAFETY:` comment.
> 
> If Joel agrees, I will amend the comments accordingly in my staging
> branch.

This approach sounds good to me. I am of the opinion, this "pseudocode comment"
should not change as long as the actual code's changes does not cause arithmetic
changes.

Whatever we decide, thanks for fixing it up Alex.

--
Joel Fernandes