On Tue, Feb 18, 2025 at 9:17 AM Maciej Wieczor-Retman
<maciej.wieczor-retman@xxxxxxxxx> wrote:
>
> From: Samuel Holland <samuel.holland@xxxxxxxxxx>
>
> This allows stack tagging to be disabled at runtime by tagging all
> stack objects with the match-all tag. This is necessary on RISC-V,
> where a kernel with KASAN_SW_TAGS enabled is expected to boot on
> hardware without pointer masking support.
Same question, is this needed on x86?
>
> Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
> Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@xxxxxxxxx>
> ---
> mm/kasan/kasan.h | 2 ++
> mm/kasan/sw_tags.c | 9 +++++++++
> 2 files changed, 11 insertions(+)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 129178be5e64..2fb26f74dff9 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -636,6 +636,8 @@ void *__asan_memset(void *addr, int c, ssize_t len);
> void *__asan_memmove(void *dest, const void *src, ssize_t len);
> void *__asan_memcpy(void *dest, const void *src, ssize_t len);
>
> +u8 __hwasan_generate_tag(void);
> +
> void __hwasan_load1_noabort(void *);
> void __hwasan_store1_noabort(void *);
> void __hwasan_load2_noabort(void *);
> diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
> index b9382b5b6a37..94465a8a3640 100644
> --- a/mm/kasan/sw_tags.c
> +++ b/mm/kasan/sw_tags.c
> @@ -71,6 +71,15 @@ u8 kasan_random_tag(void)
> return (u8)(state % (KASAN_TAG_MAX + 1));
> }
>
> +u8 __hwasan_generate_tag(void)
> +{
> + if (!kasan_enabled())
> + return KASAN_TAG_KERNEL;
> +
> + return kasan_random_tag();
> +}
> +EXPORT_SYMBOL(__hwasan_generate_tag);
> +
> bool kasan_check_range(const void *addr, size_t size, bool write,
> unsigned long ret_ip)
> {
> --
> 2.47.1
>
