This adds tests which will validate architecture page table helpers and
other accessors in their compliance with expected generic MM semantics.
This will help various architectures in validating changes to existing
page table helpers or addition of new ones.
This test covers basic page table entry transformations including but not
limited to old, young, dirty, clean, write, write protect etc at various
level along with populating intermediate entries with next page table page
and validating them.
Test page table pages are allocated from system memory with required size
and alignments. The mapped pfns at page table levels are derived from a
real pfn representing a valid kernel text symbol. This test gets called
inside kernel_init() right after async_synchronize_full().
This test gets built and run when CONFIG_DEBUG_VM_PGTABLE is selected. Any
architecture, which is willing to subscribe this test will need to select
ARCH_HAS_DEBUG_VM_PGTABLE. For now this is limited to arc, arm64, x86, s390
and ppc32 platforms where the test is known to build and run successfully.
Going forward, other architectures too can subscribe the test after fixing
any build or runtime problems with their page table helpers. Meanwhile for
better platform coverage, the test can also be enabled with CONFIG_EXPERT
even without ARCH_HAS_DEBUG_VM_PGTABLE.
Folks interested in making sure that a given platform's page table helpers
conform to expected generic MM semantics should enable the above config
which will just trigger this test during boot. Any non conformity here will
be reported as an warning which would need to be fixed. This test will help
catch any changes to the agreed upon semantics expected from generic MM and
enable platforms to accommodate it thereafter.
Cc: Andrew Morton
Cc: Vlastimil Babka
Cc: Greg Kroah-Hartman
Cc: Thomas Gleixner
Cc: Mike Rapoport
Cc: Jason Gunthorpe
Cc: Dan Williams
Cc: Peter Zijlstra
Cc: Michal Hocko
Cc: Mark Rutland
Cc: Mark Brown
Cc: Steven Price
Cc: Ard Biesheuvel
Cc: Masahiro Yamada
Cc: Kees Cook
Cc: Tetsuo Handa
Cc: Matthew Wilcox
Cc: Dave Hansen
Cc: Russell King - ARM Linux
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Martin Schwidefsky
Cc: Heiko Carstens
Cc: "David S. Miller"
Cc: Vineet Gupta
Cc: James Hogan
Cc: Paul Burton
Cc: Ralf Baechle
Cc: Kirill A. Shutemov
Cc: Gerald Schaefer
Cc: Christophe Leroy
Cc: Ingo Molnar
Cc: Richard Henderson
Cc: Ivan Kokshaysky
Cc: Matt Turner
Cc: Mark Salter
Cc: Aurelien Jacquiot
Cc: Yoshinori Sato
Cc: Brian Cain
Cc: Geert Uytterhoeven
Cc: Michal Simek
Cc: Paul Walmsley
Cc: Palmer Dabbelt
Cc: Guan Xuetao
Cc: Chris Zankel
Cc: Max Filippov
Cc: Qian Cai
Cc: linux-al...@vger.kernel.org
Cc: linux-c6x-...@linux-c6x.org
Cc: uclinux-h8-de...@lists.sourceforge.jp
Cc: linux-hexa...@vger.kernel.org
Cc: linux-m...@lists.linux-m68k.org
Cc: linux-ri...@lists.infradead.org
Cc: linux-xte...@linux-xtensa.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-m...@vger.kernel.org
Cc: linux-arm-ker...@lists.infradead.org
Cc: linux-i...@vger.kernel.org
Cc: linuxppc-...@lists.ozlabs.org
Cc: linux-s...@vger.kernel.org
Cc: linux...@vger.kernel.org
Cc: sparcli...@vger.kernel.org
Cc: x...@kernel.org
Cc: linux-ker...@vger.kernel.org
Suggested-by: Catalin Marinas
Reviewed-by: Ingo Molnar
Tested-by: Gerald Schaefer # s390
Tested-by: Christophe Leroy# ppc32
Signed-off-by: Andrew Morton
Signed-off-by: Christophe Leroy
Signed-off-by: Anshuman Khandual
---
This adds a test validation for architecture exported page table helpers.
Patch adds basic transformation tests at various levels of the page table.
This test was originally suggested by Catalin during arm64 THP migration
RFC discussion earlier. Going forward it can include more specific tests
with respect to various generic MM functions like THP, HugeTLB etc and
platform specific tests.
https://lore.kernel.org/linux-mm/20190628102003.ga56...@arrakis.emea.arm.com/
Needs to be applied on linux V5.5
Changes in V13:
- Subscribed s390 platform and updated debug-vm-pgtable/arch-support.txt per
Gerald
- Dropped keyword 'extern' from debug_vm_pgtable() declaration per Christophe
- Moved debug_vm_pgtable() declarations to per Christophe
- Moved debug_vm_pgtable() call site into kernel_init() per Christophe
- Changed CONFIG_DEBUG_VM_PGTABLE rules per Christophe
- Updated commit to include new supported platforms and changed config selection
Changes in V12:
(https://patchwork.kernel.org/project/linux-mm/list/?series=233905)
- Replaced __mmdrop() with mmdrop()
- Enable ARCH_HAS_DEBUG_VM_PGTABLE on X86 for non CONFIG_X86_PAE platforms as
the
test procedure interfere with pre-allocated PMDs attached to the PGD resulting
in runtime failures with VM_BUG_ON()
Changes in V11:
(https://patchwork.kernel.org/project/linux-mm/list/?series=221135)
- Rebased the patch on V5.4
Changes in V10:
(https://patchwork.kernel.org/project/linux-mm/list/?series=205529)
- Always enable DEBUG_VM_PG
