Re: [PATCH 0/3] arm64: kasan: support CONFIG_KASAN_VMALLOC

[Lecopzer Chen <lecopzer.chen@mediatek.com>]

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