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

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Message-ID: <CACT4Y+ZPUF8D7xB0PuDC+uqE5sY3=+rv-Fic2NsZX-ZWz+V0jg@mail.gmail.com>
Date:   Mon, 13 Mar 2017 08:25:42 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "x86@...nel.org" <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Andy Lutomirski <luto@...capital.net>,
        Michal Hocko <mhocko@...e.com>, linux-arch@...r.kernel.org,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: Re: [PATCH 19/26] x86/kasan: extend to support 5-level paging

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

+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
>