Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Lecopzer Chen <lecopzer.chen@mediatek.com>
To:     <andreyknvl@google.com>
CC:     <akpm@linux-foundation.org>, <aryabinin@virtuozzo.com>,
        <catalin.marinas@arm.com>, <dan.j.williams@intel.com>,
        <dvyukov@google.com>, <glider@google.com>,
        <kasan-dev@googlegroups.com>, <lecopzer.chen@mediatek.com>,
        <lecopzer@gmail.com>, <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-mediatek@lists.infradead.org>, <linux-mm@kvack.org>,
        <will@kernel.org>, <yj.chiang@mediatek.com>
Subject: Re: [PATCH 0/3] arm64: kasan: support CONFIG_KASAN_VMALLOC
Date:   Sat, 9 Jan 2021 15:34:23 +0800
Message-ID: <20210109073423.7304-1-lecopzer.chen@mediatek.com>
In-Reply-To: <CAAeHK+xaVvvMfd8LhPssYi+mjS-3OVsDaiNq2Li+J7JLF6k3Gg@mail.gmail.com>
References: <CAAeHK+xaVvvMfd8LhPssYi+mjS-3OVsDaiNq2Li+J7JLF6k3Gg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Hi Andrey,
>  
> On Sun, Jan 3, 2021 at 6:12 PM 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,
> > but not test for HW_TAG(I have no proper device), thus keep
> > HW_TAG and KASAN_VMALLOC mutual exclusion until confirming
> > the functionality.
> 
> Re this: it makes sense to introduce vmalloc support one step a time
> and add SW_TAGS support before taking on HW_TAGS. SW_TAGS doesn't
> require any special hardware. Working on SW_TAGS first will also allow
> dealing with potential conflicts between vmalloc and tags without
> having MTE in the picture as well. Just FYI, no need to include that
> in this change.

Thanks for the information and suggestion, so this serise I'll keep 
only for KASAN_GENERIC support :)


BRs,
Lecopzer