Re: [PATCH v3 1/4] riscv: implement user_access_begin() and families

[Cyril Bur]

On 15/3/2025 12:28 am, Alexandre Ghiti wrote:
> Hi Cyril,
>
>
> There is a bunch of checkpatch errors to fix, see https:// 
> gist.github.com/linux-riscv-bot/98f23fd1b04d6da7c23c6cb18245a158
>
> Why isn't there an implementation for unsafe_copy_from_user()? Let's 
> take the following example:
>
> user_access_begin()
> unsafe_copy_from_user()
> unsafe_get_user() <==== This one will fail since unsafe_copy_from_user() 
> -> raw_copy_from_user() -> __asm_vector_usercopy() which enables and 
> disables the SUM bit.
> user_access_end()
>
> Another thing is that with this patch, we lose the vectorized user 
> access functions, can you fix that too?

I've just been looking at doing that. I think teasing out an 'unsafe' 
style vectorised version and shoehorning it into this patch will be too 
much.

Would it be possible for me to do this as a separate series? I'm 
motivated to have this happen - we have a vector unit, we'll definitely 
want to use it.

I will add that a 'standard' copy_to_user() would still find its way to 
calling raw_copy_to_user() and so could be vectorised if all other 
criteria are met.

Thanks,

Cyril

> Thanks,
>
> Alex