[RFCv2 PATCH 0/4] powerpc: KASAN for 64-bit Book3E

Daniel Axtens dja at axtens.net
Tue Mar 12 12:23:44 AEDT 2019

Building on the work of Christophe, Aneesh and Balbir, I've ported
KASAN to the e6500, a 64-bit Book3E processor which doesn't have a
hashed page table. It applies on top of Christophe's series, v9, plus
the proposed new version of patch 2.

It requires some changes to the KASAN core; we use the less ugly
outline readiness check patch proposed by Christophe.

The KASAN shadow area is mapped into vmemmap space:
0x8000 0400 0000 0000 to 0x8000 0600 0000 0000.
To do this we require that vmemmap be disabled. (This is the default
in the kernel config that QorIQ provides for the machine in their
SDK anyway - they use flat memory.)

Only outline instrumentation is supported and only KASAN_MINIMAL works.
Only the kernel linear mapping (0xc000...) is checked. The vmalloc and
ioremap areas (also in 0x800...) are all mapped to a zero page. As
with the Book3S hash series, this requires overriding the memory <->
shadow mapping.

Also, as with both previous 64-bit series, early instrumentation is not

KVM, kexec and xmon have not been tested.

Thanks to those who have done the heavy lifting over the past several years:
 - Christophe's 32 bit series: https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-February/185379.html
 - Aneesh's Book3S hash series: https://lwn.net/Articles/655642/
 - Balbir's Book3S radix series: https://patchwork.ozlabs.org/patch/795211/

While useful if you have an Book3E device, this is mostly intended as
a warm-up exercise for reviving Aneesh's series for book3s hash. I
expect that the changes to the KASAN core will be required for that
too, but I'll check against the book3s version before I send a non-RFC
version. Once I do that I'll revisit the vmemmap decision as well.

Changes from RFCv1:

 - Use Christophe's new version of outline readiness check
 - Rebase on top of Christophe's v9 + the proposed changes to
   string/memory functions


Daniel Axtens (4):
  kasan: do not open-code addr_has_shadow
  kasan: allow architectures to manage the memory-to-shadow mapping
  kasan: allow architectures to provide an outline readiness check
  powerpc: KASAN for 64bit Book3E

 arch/powerpc/Kconfig                         |  1 +
 arch/powerpc/Kconfig.debug                   |  2 +-
 arch/powerpc/include/asm/kasan.h             | 73 +++++++++++++++++++-
 arch/powerpc/mm/Makefile                     |  2 +
 arch/powerpc/mm/kasan/Makefile               |  1 +
 arch/powerpc/mm/kasan/kasan_init_book3e_64.c | 53 ++++++++++++++
 include/linux/kasan.h                        |  6 ++
 mm/kasan/generic.c                           |  6 +-
 mm/kasan/generic_report.c                    |  2 +-
 mm/kasan/kasan.h                             |  6 +-
 mm/kasan/report.c                            |  6 +-
 mm/kasan/tags.c                              |  3 +-
 12 files changed, 149 insertions(+), 12 deletions(-)
 create mode 100644 arch/powerpc/mm/kasan/kasan_init_book3e_64.c


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