Re: [PATCH V12] mm/debug: Add tests validating architecture page table helpers

On 01/28/2020 06:57 AM, Anshuman Khandual wrote:

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
right after page_alloc_init_late().

This gets build and run when CONFIG_DEBUG_VM_PGTABLE is selected along with
CONFIG_VM_DEBUG. Architectures willing to subscribe this test also need to
select CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE which for now is limited to x86 and
arm64. Going forward, other architectures too can enable this after fixing
build or runtime problems (if any) with their page table helpers.

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 <akpm@linux-foundation.org>
Cc: Vlastimil Babka <redacted>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Thomas Gleixner <redacted>
Cc: Mike Rapoport <redacted>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Dan Williams <redacted>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Steven Price <Steven.Price@arm.com>
Cc: Ard Biesheuvel <redacted>
Cc: Masahiro Yamada <redacted>
Cc: Kees Cook <redacted>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sri Krishna chowdary <redacted>
Cc: Dave Hansen <redacted>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <redacted>
Cc: Martin Schwidefsky <redacted>
Cc: Heiko Carstens <redacted>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Vineet Gupta <redacted>
Cc: James Hogan <jhogan@kernel.org>
Cc: Paul Burton <redacted>
Cc: Ralf Baechle <redacted>
Cc: Kirill A. Shutemov <redacted>
Cc: Gerald Schaefer <redacted>
Cc: Christophe Leroy <redacted>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org

I should have included mailing lists for all missing platforms here.
Will add them in the patch next time around but for now just adding
them here explicitly so that hopefully in case some of them can build
and run the test successfully on respective platforms.

ALPHA:

+ linux-alpha@vger.kernel.org
+ Richard Henderson [off-list ref]
+ Ivan Kokshaysky [off-list ref]
+ Matt Turner [off-list ref]

C6X:

+ linux-c6x-dev@linux-c6x.org
+ Mark Salter [off-list ref]
+ Aurelien Jacquiot [off-list ref]

H8300:

+ uclinux-h8-devel@lists.sourceforge.jp
+ Yoshinori Sato [off-list ref]

HEXAGON:

+ linux-hexagon@vger.kernel.org
+ Brian Cain [off-list ref]

M68K:

+ linux-m68k@lists.linux-m68k.org
+ Geert Uytterhoeven [off-list ref]

MICROBLAZE:

+ Michal Simek [off-list ref]

RISCV:

+ linux-riscv@lists.infradead.org
+ Paul Walmsley [off-list ref]
+ Palmer Dabbelt [off-list ref]

UNICORE32:

+ Guan Xuetao [off-list ref]

XTENSA:

+ linux-xtensa@linux-xtensa.org
+ Chris Zankel [off-list ref]
+ Max Filippov [off-list ref]

Please feel free to add others if I have missed.