Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <cover.1605046192.git.andreyknvl@google.com> <619cb0edad35d946c4796976c25bddb5b3eb0c56.1605046192.git.andreyknvl@google.com>
In-Reply-To: <619cb0edad35d946c4796976c25bddb5b3eb0c56.1605046192.git.andreyknvl@google.com>
From:   Alexander Potapenko <glider@google.com>
Date:   Wed, 11 Nov 2020 16:03:52 +0100
Message-ID: <CAG_fn=UKSp8shtYujRbM=8ndhLg_Ccdpk9eSfOeb=KpwNi7HBg@mail.gmail.com>
Subject: Re: [PATCH v9 17/44] kasan, arm64: move initialization message
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Marco Elver <elver@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> w=
rote:
>
> Software tag-based KASAN mode is fully initialized with kasan_init_tags()=
,
> while the generic mode only requires kasan_init(). Move the
> initialization message for tag-based mode into kasan_init_tags().
>
> Also fix pr_fmt() usage for KASAN code: generic.c doesn't need it as it
> doesn't use any printing functions; tag-based mode should use "kasan:"
> instead of KBUILD_MODNAME (which stands for file name).
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
> Change-Id: Iddca9764b30ff0fab1922f26ca9d4f39b6f22673
> ---
>  arch/arm64/include/asm/kasan.h |  9 +++------
>  arch/arm64/mm/kasan_init.c     | 13 +++++--------
>  mm/kasan/generic.c             |  2 --
>  mm/kasan/sw_tags.c             |  4 +++-
>  4 files changed, 11 insertions(+), 17 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kasan.h b/arch/arm64/include/asm/kasa=
n.h
> index f7ea70d02cab..0aaf9044cd6a 100644
> --- a/arch/arm64/include/asm/kasan.h
> +++ b/arch/arm64/include/asm/kasan.h
> @@ -12,14 +12,10 @@
>  #define arch_kasan_reset_tag(addr)     __tag_reset(addr)
>  #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)
>
> +void kasan_init(void);
> +
>  /*
>   * KASAN_SHADOW_START: beginning of the kernel virtual addresses.
>   * KASAN_SHADOW_END: KASAN_SHADOW_START + 1/N of kernel virtual addresse=
s,
> @@ -43,6 +39,7 @@ 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 5172799f831f..e35ce04beed1 100644
> --- a/arch/arm64/mm/kasan_init.c
> +++ b/arch/arm64/mm/kasan_init.c
> @@ -278,17 +278,14 @@ static void __init kasan_init_depth(void)
>         init_task.kasan_depth =3D 0;
>  }
>
> -#else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS) */
> -
> -static inline void __init kasan_init_shadow(void) { }
> -
> -static inline void __init kasan_init_depth(void) { }
> -
> -#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> -
>  void __init kasan_init(void)
>  {
>         kasan_init_shadow();
>         kasan_init_depth();
> +#if defined(CONFIG_KASAN_GENERIC)
> +       /* CONFIG_KASAN_SW_TAGS also requires kasan_init_tags(). */
>         pr_info("KernelAddressSanitizer initialized\n");
> +#endif
>  }

Cannot we have a single kasan_init() function that will call
tool-specific initialization functions and print the message at the
end?

> +
> +#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index e1af3b6c53b8..adb254df1b1d 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -9,8 +9,6 @@
>   *        Andrey Konovalov <andreyknvl@gmail.com>
>   */
>
> -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> -
>  #include <linux/export.h>
>  #include <linux/interrupt.h>
>  #include <linux/init.h>
> diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
> index b2638c2cd58a..d25f8641b7cd 100644
> --- a/mm/kasan/sw_tags.c
> +++ b/mm/kasan/sw_tags.c
> @@ -6,7 +6,7 @@
>   * Author: Andrey Konovalov <andreyknvl@google.com>
>   */
>
> -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +#define pr_fmt(fmt) "kasan: " fmt
>
>  #include <linux/export.h>
>  #include <linux/interrupt.h>
> @@ -41,6 +41,8 @@ void kasan_init_tags(void)
>
>         for_each_possible_cpu(cpu)
>                 per_cpu(prng_state, cpu) =3D (u32)get_cycles();
> +
> +       pr_info("KernelAddressSanitizer initialized\n");
>  }
>
>  /*
> --
> 2.29.2.222.g5d2a92d10f8-goog
>


--=20
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Stra=C3=9Fe, 33
80636 M=C3=BCnchen

Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg