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    SubjectRe: [PATCH AUTOSEL 5.19 54/64] ARM: 9202/1: kasan: support CONFIG_KASAN_VMALLOC
    On Sun, 14 Aug 2022 at 17:30, Sasha Levin <sashal@kernel.org> wrote:
    >
    > From: Lecopzer Chen <lecopzer.chen@mediatek.com>
    >
    > [ Upstream commit 565cbaad83d83e288927b96565211109bc984007 ]
    >
    > Simply make shadow of vmalloc area mapped on demand.
    >
    > Since the virtual address of vmalloc for Arm is also between
    > MODULE_VADDR and 0x100000000 (ZONE_HIGHMEM), which means the shadow
    > address has already included between KASAN_SHADOW_START and
    > KASAN_SHADOW_END.
    > Thus we need to change nothing for memory map of Arm.
    >
    > This can fix ARM_MODULE_PLTS with KASan, support KASan for higmem
    > and support CONFIG_VMAP_STACK with KASan.
    >
    > Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
    > Tested-by: Linus Walleij <linus.walleij@linaro.org>
    > Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
    > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
    > Signed-off-by: Sasha Levin <sashal@kernel.org>

    This patch does not belong in -stable. It has no fixes: or cc:stable
    tags, and the contents are completely inappropriate for backporting
    anywhere. In general, I think that no patch that touches arch/arm
    (with the exception of DTS updates, perhaps) should ever be backported
    unless proposed or acked by the maintainer.

    I know I shouldn't ask, but how were these patches build/boot tested?
    KAsan is very tricky to get right, especially on 32-bit ARM ...

    > ---
    > arch/arm/Kconfig | 1 +
    > arch/arm/mm/kasan_init.c | 6 +++++-
    > 2 files changed, 6 insertions(+), 1 deletion(-)
    >
    > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
    > index 7630ba9cb6cc..545d2d4a492b 100644
    > --- a/arch/arm/Kconfig
    > +++ b/arch/arm/Kconfig
    > @@ -75,6 +75,7 @@ config ARM
    > select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
    > select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
    > select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
    > + select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
    > select HAVE_ARCH_MMAP_RND_BITS if MMU
    > select HAVE_ARCH_PFN_VALID
    > select HAVE_ARCH_SECCOMP
    > diff --git a/arch/arm/mm/kasan_init.c b/arch/arm/mm/kasan_init.c
    > index 5ad0d6c56d56..29caee9c79ce 100644
    > --- a/arch/arm/mm/kasan_init.c
    > +++ b/arch/arm/mm/kasan_init.c
    > @@ -236,7 +236,11 @@ void __init kasan_init(void)
    >
    > clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
    >
    > - kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
    > + if (!IS_ENABLED(CONFIG_KASAN_VMALLOC))
    > + kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
    > + kasan_mem_to_shadow((void *)VMALLOC_END));
    > +
    > + kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_END),
    > kasan_mem_to_shadow((void *)-1UL) + 1);
    >
    > for_each_mem_range(i, &pa_start, &pa_end) {
    > --
    > 2.35.1
    >

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