Rick Edgecombe [off-list ref] writes:

The x86 Control-flow Enforcement Technology (CET) feature includes a new
type of memory called shadow stack. This shadow stack memory has some
unusual properties, which requires some core mm changes to function
properly.

...

---
Hi Non-x86 Arch’s,

x86 has a feature that allows for the creation of a special type of
writable memory (shadow stack) that is only writable in limited specific
ways. Previously, changes were proposed to core MM code to teach it to
decide when to create normally writable memory or the special shadow stack
writable memory, but David Hildenbrand suggested[0] to change
pXX_mkwrite() to take a VMA, so awareness of shadow stack memory can be
moved into x86 code.

Since pXX_mkwrite() is defined in every arch, it requires some tree-wide
changes. So that is why you are seeing some patches out of a big x86
series pop up in your arch mailing list. There is no functional change.
After this refactor, the shadow stack series goes on to use the arch
helpers to push shadow stack memory details inside arch/x86.

...

---
 Documentation/mm/arch_pgtable_helpers.rst    |  9 ++++++---
 arch/alpha/include/asm/pgtable.h             |  6 +++++-
 arch/arc/include/asm/hugepage.h              |  2 +-
 arch/arc/include/asm/pgtable-bits-arcv2.h    |  7 ++++++-
 arch/arm/include/asm/pgtable-3level.h        |  7 ++++++-
 arch/arm/include/asm/pgtable.h               |  2 +-
 arch/arm64/include/asm/pgtable.h             |  4 ++--
 arch/csky/include/asm/pgtable.h              |  2 +-
 arch/hexagon/include/asm/pgtable.h           |  2 +-
 arch/ia64/include/asm/pgtable.h              |  2 +-
 arch/loongarch/include/asm/pgtable.h         |  4 ++--
 arch/m68k/include/asm/mcf_pgtable.h          |  2 +-
 arch/m68k/include/asm/motorola_pgtable.h     |  6 +++++-
 arch/m68k/include/asm/sun3_pgtable.h         |  6 +++++-
 arch/microblaze/include/asm/pgtable.h        |  2 +-
 arch/mips/include/asm/pgtable.h              |  6 +++---
 arch/nios2/include/asm/pgtable.h             |  2 +-
 arch/openrisc/include/asm/pgtable.h          |  2 +-
 arch/parisc/include/asm/pgtable.h            |  6 +++++-
 arch/powerpc/include/asm/book3s/32/pgtable.h |  2 +-
 arch/powerpc/include/asm/book3s/64/pgtable.h |  4 ++--
 arch/powerpc/include/asm/nohash/32/pgtable.h |  2 +-
 arch/powerpc/include/asm/nohash/32/pte-8xx.h |  2 +-
 arch/powerpc/include/asm/nohash/64/pgtable.h |  2 +-

Looks like you discovered the joys of ppc's at-least 5 different MMU
implementations, sorry :)

Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

cheers