Re: [PATCH v2 0/4] arm64: kasan: support CONFIG_KASAN_VMALLOC

From: Ard Biesheuvel <ardb@kernel.org>
To: Lecopzer Chen <lecopzer@gmail.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Tyler Hicks <tyhicks@linux.microsoft.com>,
	Alexander Potapenko <glider@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Will Deacon <will@kernel.org>,
	yj.chiang@mediatek.com, kasan-dev <kasan-dev@googlegroups.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Guenter Roeck <linux@roeck-us.net>,
	Andrey Konovalov <andreyknvl@google.com>,
	Mark Brown <broonie@kernel.org>,
	linux-mediatek@lists.infradead.org,
	Dan Williams <dan.j.williams@intel.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH v2 0/4] arm64: kasan: support CONFIG_KASAN_VMALLOC
Date: Wed, 3 Feb 2021 19:31:04 +0100	[thread overview]
Message-ID: <CAMj1kXE3NHBt2YdQ4ESygRZUdUZbpD66rZ6wziPi8OAqfKvNJQ@mail.gmail.com> (raw)
In-Reply-To: <20210109103252.812517-1-lecopzer@gmail.com>

On Sat, 9 Jan 2021 at 11:33, Lecopzer Chen <lecopzer@gmail.com> wrote:
>
> Linux supports KAsan for VMALLOC since commit 3c5c3cfb9ef4da9
> ("kasan: support backing vmalloc space with real shadow memory")
>
> Acroding to how x86 ported it [1], they early allocated p4d and pgd,
> but in arm64 I just simulate how KAsan supports MODULES_VADDR in arm64
> by not to populate the vmalloc area except for kimg address.
>
> Test environment:
>     4G and 8G Qemu virt,
>     39-bit VA + 4k PAGE_SIZE with 3-level page table,
>     test by lib/test_kasan.ko and lib/test_kasan_module.ko
>
> It also works in Kaslr with CONFIG_RANDOMIZE_MODULE_REGION_FULL
> and randomize module region inside vmalloc area.
>
>
> [1]: commit 0609ae011deb41c ("x86/kasan: support KASAN_VMALLOC")
>
> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
> Acked-by: Andrey Konovalov <andreyknvl@google.com>
> Tested-by: Andrey Konovalov <andreyknvl@google.com>
>
>
> v2 -> v1
>         1. kasan_init.c tweak indent
>         2. change Kconfig depends only on HAVE_ARCH_KASAN
>         3. support randomized module region.
>
> v1:
> https://lore.kernel.org/lkml/20210103171137.153834-1-lecopzer@gmail.com/
>
> Lecopzer Chen (4):
>   arm64: kasan: don't populate vmalloc area for CONFIG_KASAN_VMALLOC
>   arm64: kasan: abstract _text and _end to KERNEL_START/END
>   arm64: Kconfig: support CONFIG_KASAN_VMALLOC
>   arm64: kaslr: support randomized module area with KASAN_VMALLOC
>

I failed to realize that VMAP_STACK and KASAN are currently mutually
exclusive on arm64, and that this series actually fixes that, which is
a big improvement, so it would make sense to call that out.

This builds and runs fine for me on a VM running under KVM.

Tested-by: Ard Biesheuvel <ardb@kernel.org>

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