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    Subject[PATCH 5.4 234/261] powerpc/32: Disable KASAN with pages bigger than 16k
    Date
    From: Christophe Leroy <christophe.leroy@csgroup.eu>

    commit 888468ce725a4cd56d72dc7e5096078f7a9251a0 upstream.

    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 128MB starting at 0xf8000000.
    With 4k pages, a PGD entry is 4MB
    With 16k pages, a PGD entry is 64MB
    With 64k pages, a PGD entry is 1GB which is too big.

    Until we rework the early shadow mapping, disable KASAN when the page
    size is too big.

    Fixes: 2edb16efc899 ("powerpc/32: Add KASAN support")
    Cc: stable@vger.kernel.org # v5.2+
    Reported-by: kbuild test robot <lkp@intel.com>
    Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/7195fcde7314ccbf7a081b356084a69d421b10d4.1590660977.git.christophe.leroy@csgroup.eu
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/powerpc/Kconfig | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/arch/powerpc/Kconfig
    +++ b/arch/powerpc/Kconfig
    @@ -171,7 +171,7 @@ 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 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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