On Sat, 9 Jan 2021 at 11:33, Lecopzer Chen [off-list ref] 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 <redacted>
Acked-by: Andrey Konovalov <redacted>
Tested-by: Andrey Konovalov <redacted>


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/ (local)

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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