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mm/debug: add tests validating architecture page table helpers

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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
via late_initcall().

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 powerpc 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.

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.

[anshuman.khandual@arm.com: v17]
  Link: http://lkml.kernel.org/r/1587436495-22033-3-git-send-email-anshuman.khandual@arm.com
[anshuman.khandual@arm.com: v18]
  Link: http://lkml.kernel.org/r/1588564865-31160-3-git-send-email-anshuman.khandual@arm.com
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>	[s390]
Tested-by: Christophe Leroy <christophe.leroy@c-s.fr>	[ppc32]
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Link: http://lkml.kernel.org/r/1583919272-24178-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Anshuman Khandual
2020-06-04 16:47:15 -07:00
committed by Linus Torvalds
parent 8898ad58a0
commit 399145f9eb
9 changed files with 444 additions and 0 deletions
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22
lib/Kconfig.debug
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@@ -658,6 +658,12 @@ config SCHED_STACK_END_CHECK
data corruption or a sporadic crash at a later stage once the region
is examined. The runtime overhead introduced is minimal.
config ARCH_HAS_DEBUG_VM_PGTABLE
bool
help
An architecture should select this when it can successfully
build and run DEBUG_VM_PGTABLE.
config DEBUG_VM
bool "Debug VM"
depends on DEBUG_KERNEL
@@ -693,6 +699,22 @@ config DEBUG_VM_PGFLAGS
If unsure, say N.
config DEBUG_VM_PGTABLE
bool "Debug arch page table for semantics compliance"
depends on MMU
depends on ARCH_HAS_DEBUG_VM_PGTABLE
default y if DEBUG_VM
help
This option provides a debug method which can be used to test
architecture page table helper functions on various platforms in
verifying if they comply with expected generic MM semantics. This
will help architecture code in making sure that any changes or
new additions of these helpers still conform to expected
semantics of the generic MM. Platforms will have to opt in for
this through ARCH_HAS_DEBUG_VM_PGTABLE.
If unsure, say N.
config ARCH_HAS_DEBUG_VIRTUAL
bool