linux-kernel - Re: [PATCH v3] kasan: add kasan mode messages when kasan init

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Date:   Fri, 22 Oct 2021 14:28:59 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Kuan-Ying Lee <Kuan-Ying.Lee@...iatek.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Marco Elver <elver@...gle.com>
Cc:     chinwen.chang@...iatek.com, yee.lee@...iatek.com,
        nicholas.tang@...iatek.com, kasan-dev@...glegroups.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v3] kasan: add kasan mode messages when kasan init

On 20.10.21 11:48, Kuan-Ying Lee wrote:
> There are multiple kasan modes. It makes sense that we add some messages
> to know which kasan mode is when booting up. see [1].

s/is/is active/ ?

Looks reasonable to me

Reviewed-by: David Hildenbrand <david@...hat.com>

> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=212195 [1]
> Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@...iatek.com>
> ---
> v3:
>  - Rebase to linux-next
>  - Move kasan_mode_info() into hw_tags.c
> v2:
>  - Rebase to linux-next
>  - HW-tag based mode need to consider asymm mode
>  - Thanks Marco's suggestion
> 
>  arch/arm64/mm/kasan_init.c |  2 +-
>  mm/kasan/hw_tags.c         | 14 +++++++++++++-
>  mm/kasan/sw_tags.c         |  2 +-
>  3 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
> index 5b996ca4d996..6f5a6fe8edd7 100644
> --- a/arch/arm64/mm/kasan_init.c
> +++ b/arch/arm64/mm/kasan_init.c
> @@ -309,7 +309,7 @@ void __init kasan_init(void)
>  	kasan_init_depth();
>  #if defined(CONFIG_KASAN_GENERIC)
>  	/* CONFIG_KASAN_SW_TAGS also requires kasan_init_sw_tags(). */
> -	pr_info("KernelAddressSanitizer initialized\n");
> +	pr_info("KernelAddressSanitizer initialized (generic)\n");
>  #endif
>  }
>  
> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> index dc892119e88f..7355cb534e4f 100644
> --- a/mm/kasan/hw_tags.c
> +++ b/mm/kasan/hw_tags.c
> @@ -106,6 +106,16 @@ static int __init early_kasan_flag_stacktrace(char *arg)
>  }
>  early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
>  
> +static inline const char *kasan_mode_info(void)
> +{
> +	if (kasan_mode == KASAN_MODE_ASYNC)
> +		return "async";
> +	else if (kasan_mode == KASAN_MODE_ASYMM)
> +		return "asymm";
> +	else
> +		return "sync";
> +}
> +
>  /* kasan_init_hw_tags_cpu() is called for each CPU. */
>  void kasan_init_hw_tags_cpu(void)
>  {
> @@ -177,7 +187,9 @@ void __init kasan_init_hw_tags(void)
>  		break;
>  	}
>  
> -	pr_info("KernelAddressSanitizer initialized\n");
> +	pr_info("KernelAddressSanitizer initialized (hw-tags, mode=%s, stacktrace=%s)\n",
> +		kasan_mode_info(),
> +		kasan_stack_collection_enabled() ? "on" : "off");
>  }
>  
>  void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
> diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
> index bd3f540feb47..77f13f391b57 100644
> --- a/mm/kasan/sw_tags.c
> +++ b/mm/kasan/sw_tags.c
> @@ -42,7 +42,7 @@ void __init kasan_init_sw_tags(void)
>  	for_each_possible_cpu(cpu)
>  		per_cpu(prng_state, cpu) = (u32)get_cycles();
>  
> -	pr_info("KernelAddressSanitizer initialized\n");
> +	pr_info("KernelAddressSanitizer initialized (sw-tags)\n");
>  }
>  
>  /*
> 


-- 
Thanks,

David / dhildenb