Re: [PATCH v4 5/7] mm/x86: arch_check_zapped_pud()

Thomas Gleixner
2024-08-07T22:28:48Z

On Wed, Aug 07 2024 at 15:48, Peter Xu wrote:

> Subject: mm/x86: arch_check_zapped_pud()

Is not a proper subject line. It clearly lacks a verb.

Subject: mm/x86: Implement arch_check_zapped_pud()

> Introduce arch_check_zapped_pud() to sanity check shadow stack on PUD zaps.
> It has the same logic of the PMD helper.

s/of/as/

> +
> +void arch_check_zapped_pud(struct vm_area_struct *vma, pud_t pud)
> +{
> + /* See note in arch_check_zapped_pte() */
> + VM_WARN_ON_ONCE(!(vma->vm_flags & VM_SHADOW_STACK) &&
> + pud_shstk(pud));

Please get rid of the line break. You have 100 characters.

> +}
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 2a6a3cccfc36..2289e9f7aa1b 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -447,6 +447,13 @@ static inline void arch_check_zapped_pmd(struct vm_area_struct *vma,
> }
> #endif
>
> +#ifndef arch_check_zapped_pud
> +static inline void arch_check_zapped_pud(struct vm_area_struct *vma,
> + pud_t pud)
> +{

Ditto..

> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 0024266dea0a..81c5da0708ed 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c

Why is a mm change burried in a patch which is named mm/x86?

It's clearly documented that core changes with the generic fallback come
in one patch and the architecture override in a separate one afterwards.

Do we write documentation just for the sake of writing it?

Thanks,

tglx