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SubjectRe: [PATCH] powerpc/32: disable KASAN with pages bigger than 16k
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Le 28/05/2020 à 12:17, Christophe Leroy a écrit :
> Mapping of early shadow area is implemented by using a single static
> page table having all entries pointing to the same early shadow page.
> The shadow area must therefore occupy full PGD entries.
>
> The shadow area has a size of 128Mbytes starting at 0xf8000000.
> With 4k pages, a PGD entry is 4Mbytes
> With 16k pages, a PGD entry is 64Mbytes
> With 64k pages, a PGD entry is 256Mbytes which is too big.

That's for 32k pages that a PGD is 256Mbytes.

With 64k pages, a PGD entry is 1Gbytes which is too big.

Michael, can you fix the commit log ?

Thanks
Christophe

>
> Until we rework the early shadow mapping, disable KASAN when the
> page size is too big.
>
> Reported-by: kbuild test robot <lkp@intel.com>
> Fixes: 2edb16efc899 ("powerpc/32: Add KASAN support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
> arch/powerpc/Kconfig | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 1dfa59126fcf..066b36bf9efa 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -169,8 +169,8 @@ config PPC
> select HAVE_ARCH_AUDITSYSCALL
> select HAVE_ARCH_HUGE_VMAP if PPC_BOOK3S_64 && PPC_RADIX_MMU
> select HAVE_ARCH_JUMP_LABEL
> - select HAVE_ARCH_KASAN if PPC32
> - select HAVE_ARCH_KASAN_VMALLOC if PPC32
> + select HAVE_ARCH_KASAN if PPC32 && PPC_PAGE_SHIFT <= 14
> + select HAVE_ARCH_KASAN_VMALLOC if PPC32 && PPC_PAGE_SHIFT <= 14
> select HAVE_ARCH_KGDB
> select HAVE_ARCH_MMAP_RND_BITS
> select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
>

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