Re: [PATCH 19/26] x86/kasan: extend to support 5-level paging

[Dmitry Vyukov]

On Mon, Mar 13, 2017 at 6:50 AM, Kirill A. Shutemov
<kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
> This patch bring support for non-folded additional page table level.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx

+Andrey Ryabinin

> ---
>  arch/x86/mm/kasan_init_64.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
> index 733f8ba6a01f..bcabc56e0dc4 100644
> --- a/arch/x86/mm/kasan_init_64.c
> +++ b/arch/x86/mm/kasan_init_64.c
> @@ -50,8 +50,18 @@ static void __init kasan_map_early_shadow(pgd_t *pgd)
>         unsigned long end = KASAN_SHADOW_END;
>
>         for (i = pgd_index(start); start < end; i++) {
> -               pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud)
> -                               | _KERNPG_TABLE);
> +               switch (CONFIG_PGTABLE_LEVELS) {
> +               case 4:
> +                       pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud) |
> +                                       _KERNPG_TABLE);
> +                       break;
> +               case 5:
> +                       pgd[i] = __pgd(__pa_nodebug(kasan_zero_p4d) |
> +                                       _KERNPG_TABLE);
> +                       break;
> +               default:
> +                       BUILD_BUG();
> +               }
>                 start += PGDIR_SIZE;
>         }
>  }
> @@ -79,6 +89,7 @@ void __init kasan_early_init(void)
>         pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL;
>         pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
>         pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
> +       p4dval_t p4d_val = __pa_nodebug(kasan_zero_pud) | _KERNPG_TABLE;
>
>         for (i = 0; i < PTRS_PER_PTE; i++)
>                 kasan_zero_pte[i] = __pte(pte_val);
> @@ -89,6 +100,9 @@ void __init kasan_early_init(void)
>         for (i = 0; i < PTRS_PER_PUD; i++)
>                 kasan_zero_pud[i] = __pud(pud_val);
>
> +       for (i = 0; CONFIG_PGTABLE_LEVELS >= 5 && i < PTRS_PER_P4D; i++)
> +               kasan_zero_p4d[i] = __p4d(p4d_val);
> +
>         kasan_map_early_shadow(early_level4_pgt);
>         kasan_map_early_shadow(init_level4_pgt);
>  }
> --
> 2.11.0
>