linux-kernel - Re: [PATCH v9 4/6] kasan: Document support on 32-bit powerpc

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Message-ID: <421d8685-afef-eaa8-5207-280d951be594@csgroup.eu>
Date:   Tue, 1 Dec 2020 17:56:29 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Daniel Axtens <dja@...ens.net>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org,
        kasan-dev@...glegroups.com, christophe.leroy@....fr,
        aneesh.kumar@...ux.ibm.com, bsingharora@...il.com
Subject: Re: [PATCH v9 4/6] kasan: Document support on 32-bit powerpc



Le 01/12/2020 à 17:16, Daniel Axtens a écrit :
> KASAN is supported on 32-bit powerpc and the docs should reflect this.
> 
> Document s390 support while we're at it.
> 
> Suggested-by: Christophe Leroy <christophe.leroy@....fr>
> Reviewed-by: Christophe Leroy <christophe.leroy@....fr>

My new address is <christophe.leroy@...roup.eu>

> Signed-off-by: Daniel Axtens <dja@...ens.net>
> ---
>   Documentation/dev-tools/kasan.rst |  7 +++++--
>   Documentation/powerpc/kasan.txt   | 12 ++++++++++++
>   2 files changed, 17 insertions(+), 2 deletions(-)
>   create mode 100644 Documentation/powerpc/kasan.txt
> 
> diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
> index 2b68addaadcd..eaf868094a8e 100644
> --- a/Documentation/dev-tools/kasan.rst
> +++ b/Documentation/dev-tools/kasan.rst
> @@ -19,7 +19,8 @@ out-of-bounds accesses for global variables is only supported since Clang 11.
>   Tag-based KASAN is only supported in Clang.
>   
>   Currently generic KASAN is supported for the x86_64, arm64, xtensa, s390 and
> -riscv architectures, and tag-based KASAN is supported only for arm64.
> +riscv architectures. It is also supported on 32-bit powerpc kernels. Tag-based
> +KASAN is supported only on arm64.
>   
>   Usage
>   -----
> @@ -255,7 +256,9 @@ CONFIG_KASAN_VMALLOC
>   ~~~~~~~~~~~~~~~~~~~~
>   
>   With ``CONFIG_KASAN_VMALLOC``, KASAN can cover vmalloc space at the
> -cost of greater memory usage. Currently this is only supported on x86.
> +cost of greater memory usage. Currently this supported on x86, s390
> +and 32-bit powerpc. It is optional, except on 32-bit powerpc kernels
> +with module support, where it is required.
>   
>   This works by hooking into vmalloc and vmap, and dynamically
>   allocating real shadow memory to back the mappings.
> diff --git a/Documentation/powerpc/kasan.txt b/Documentation/powerpc/kasan.txt
> new file mode 100644
> index 000000000000..26bb0e8bb18c
> --- /dev/null
> +++ b/Documentation/powerpc/kasan.txt
> @@ -0,0 +1,12 @@
> +KASAN is supported on powerpc on 32-bit only.
> +
> +32 bit support
> +==============
> +
> +KASAN is supported on both hash and nohash MMUs on 32-bit.
> +
> +The shadow area sits at the top of the kernel virtual memory space above the
> +fixmap area and occupies one eighth of the total kernel virtual memory space.
> +
> +Instrumentation of the vmalloc area is optional, unless built with modules,
> +in which case it is required.
>