Re: [Patch v2] x86/head/64: remove redundant check on level2_kernel_pgt's _PAGE_PRESENT bit

[Kirill A . Shutemov]

On Thu, May 23, 2024 at 08:37:52AM +0000, Wei Yang wrote:
> This patch tries to remove a redundant check on kernel code's PMD
> _PAGE_PRESENT attribute before fix up.

Tries? s/This patch tries to r/R/

> Current process looks like this:
> 
>     pmd in [0, _text)
>         unset _PAGE_PRESENT
>     pmd in [_text, _end]
>         if (_PAGE_PRESENT)
>             fix up delta
>     pmd in (_end, 512)
>         unset _PAGE_PRESENT
> 
> Since we have compiled in _PAGE_PRESENT in this page table, it is not
> necessary to check _PAGE_PRESENT again before fixing up delta

level2_kernel_pgt compiled with _PAGE_PRESENT set. The check is
redundant.


-- 
  Kiryl Shutsemau / Kirill A. Shutemov