On Fri, 2020-03-06 at 05:27 +0530, 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 > 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. OK, I get this working on powerpc hash MMU as well, so this? diff --git a/Documentation/features/debug/debug-vm-pgtable/arch-support.txt b/Documentation/features/debug/debug-vm-pgtable/arch-support.txt index 64d0f9b15c49..c527d05c0459 100644 --- a/Documentation/features/debug/debug-vm-pgtable/arch-support.txt +++ b/Documentation/features/debug/debug-vm-pgtable/arch-support.txt @@ -22,8 +22,7 @@ | nios2: | TODO | | openrisc: | TODO | | parisc: | TODO | - | powerpc/32: | ok | - | powerpc/64: | TODO | + | powerpc: | ok | | riscv: | TODO | | s390: | ok | | sh: | TODO | diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 2e7eee523ba1..176930f40e07 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -116,7 +116,7 @@ config PPC # select ARCH_32BIT_OFF_T if PPC32 select ARCH_HAS_DEBUG_VIRTUAL - select ARCH_HAS_DEBUG_VM_PGTABLE if PPC32 + select ARCH_HAS_DEBUG_VM_PGTABLE select ARCH_HAS_DEVMEM_IS_ALLOWED select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_FORTIFY_SOURCE diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c index 96a91bda3a85..98990a515268 100644 --- a/mm/debug_vm_pgtable.c +++ b/mm/debug_vm_pgtable.c @@ -256,7 +256,8 @@ static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep, pte_t pte = READ_ONCE(*ptep); pte = __pte(pte_val(pte) | RANDOM_ORVALUE); - WRITE_ONCE(*ptep, pte); + set_pte_at(mm, vaddr, ptep, pte); + barrier(); pte_clear(mm, vaddr, ptep); pte = READ_ONCE(*ptep); WARN_ON(!pte_none(pte));
