On Thu, Jan 21, 2021 at 06:44:14PM +0100, Andrey Konovalov wrote:

On Sat, Jan 9, 2021 at 11:33 AM Lecopzer Chen [off-list ref] wrote:

quoted

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

 arch/arm64/Kconfig         |  1 +
 arch/arm64/kernel/kaslr.c  | 18 ++++++++++--------
 arch/arm64/kernel/module.c | 16 +++++++++-------
 arch/arm64/mm/kasan_init.c | 29 +++++++++++++++++++++--------
 4 files changed, 41 insertions(+), 23 deletions(-)

--
2.25.1

Hi Will,

Could you PTAL at the arm64 changes?

Sorry, wanted to get to this today but I ran out of time in the end. On the
list for next week!

Will

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