On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote:
>
> This is a preparatory commit for the upcoming addition of a new hardware
> tag-based (MTE-based) KASAN mode.
>
> Hardware tag-based KASAN won't be using shadow memory. Only initialize
> it when one of the software KASAN modes are enabled.
>
> No functional changes for software modes.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
> ---
> Change-Id: I055e0651369b14d3e54cdaa8c48e6329b2e8952d
> ---
> arch/arm64/include/asm/kasan.h | 8 ++++++--
> arch/arm64/mm/kasan_init.c | 15 ++++++++++++++-
> 2 files changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kasan.h b/arch/arm64/include/asm/kasan.h
> index b0dc4abc3589..f7ea70d02cab 100644
> --- a/arch/arm64/include/asm/kasan.h
> +++ b/arch/arm64/include/asm/kasan.h
> @@ -13,6 +13,12 @@
> #define arch_kasan_get_tag(addr) __tag_get(addr)
>
> #ifdef CONFIG_KASAN
> +void kasan_init(void);
> +#else
> +static inline void kasan_init(void) { }
> +#endif
> +
> +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
>
> /*
> * KASAN_SHADOW_START: beginning of the kernel virtual addresses.
> @@ -33,12 +39,10 @@
> #define _KASAN_SHADOW_START(va) (KASAN_SHADOW_END - (1UL << ((va) - KASAN_SHADOW_SCALE_SHIFT)))
> #define KASAN_SHADOW_START _KASAN_SHADOW_START(vabits_actual)
>
> -void kasan_init(void);
> void kasan_copy_shadow(pgd_t *pgdir);
> asmlinkage void kasan_early_init(void);
>
> #else
> -static inline void kasan_init(void) { }
> static inline void kasan_copy_shadow(pgd_t *pgdir) { }
> #endif
>
> diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
> index b24e43d20667..ffeb80d5aa8d 100644
> --- a/arch/arm64/mm/kasan_init.c
> +++ b/arch/arm64/mm/kasan_init.c
> @@ -21,6 +21,8 @@
> #include <asm/sections.h>
> #include <asm/tlbflush.h>
>
> +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
> +
> static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
>
> /*
> @@ -208,7 +210,7 @@ static void __init clear_pgds(unsigned long start,
> set_pgd(pgd_offset_k(start), __pgd(0));
> }
>
> -void __init kasan_init(void)
> +static void __init kasan_init_shadow(void)
> {
> u64 kimg_shadow_start, kimg_shadow_end;
> u64 mod_shadow_start, mod_shadow_end;
> @@ -269,6 +271,17 @@ void __init kasan_init(void)
>
> memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
> cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
> +}
> +
> +#else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS) */
> +
> +static inline void __init kasan_init_shadow(void) { }
> +
> +#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> +
> +void __init kasan_init(void)
> +{
> + kasan_init_shadow();
>
> /* At this point kasan is fully initialized. Enable error messages */
> init_task.kasan_depth = 0;
> --
> 2.29.2.222.g5d2a92d10f8-goog
>
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
