Hi Matt, On Sat, Sep 5, 2026 at 9:29 PM Matt Turner <[email protected]> wrote: > > Add the page table check helpers needed for CONFIG_PAGE_TABLE_CHECK > and select ARCH_SUPPORTS_PAGE_TABLE_CHECK in Kconfig. > > Alpha does not support huge pages, so pmd_user_accessible_page() and > pud_user_accessible_page() always return false. pte_user_accessible_page() > checks for present PTEs with user read access (_PAGE_URE). > > Assisted-by: Claude:claude-opus-4-6 > Signed-off-by: Matt Turner <[email protected]> > > Update the helpers to the three-argument pxx_user_accessible_page(mm, > addr, pxx) signature introduced by commit cf8771ca4cdb ("mm/page_table_check: > Pass mm_struct to pxx_user_accessible_page()"), matching the other > architectures. > --- > arch/alpha/Kconfig | 1 + > arch/alpha/include/asm/pgtable.h | 19 +++++++++++++++++++ > 2 files changed, 20 insertions(+) > > diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig > index 1d28fa8d3b66..da4ec8399517 100644 > --- a/arch/alpha/Kconfig > +++ b/arch/alpha/Kconfig > @@ -19,6 +19,7 @@ config ALPHA > select ARCH_NO_SG_CHAIN > select ARCH_SUPPORTS_ATOMIC_RMW > select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 > + select ARCH_SUPPORTS_PAGE_TABLE_CHECK > select ARCH_USE_CMPXCHG_LOCKREF > select FORCE_PCI > select PCI_DOMAINS if PCI > diff --git a/arch/alpha/include/asm/pgtable.h > b/arch/alpha/include/asm/pgtable.h > index bdff33b505bc..6ebdd90f3035 100644 > --- a/arch/alpha/include/asm/pgtable.h > +++ b/arch/alpha/include/asm/pgtable.h > @@ -232,6 +232,25 @@ extern inline void pud_clear(pud_t * pudp) { > pud_val(*pudp) = 0; } > extern inline int pte_write(pte_t pte) { return !(pte_val(pte) & > _PAGE_FOW); } > extern inline int pte_dirty(pte_t pte) { return pte_val(pte) & > _PAGE_DIRTY; } > extern inline int pte_young(pte_t pte) { return pte_val(pte) & > _PAGE_ACCESSED; } > +extern inline int pte_user(pte_t pte) { return pte_val(pte) & > _PAGE_URE; } > + > +static inline bool pte_user_accessible_page(struct mm_struct *mm, > + unsigned long addr, pte_t pte) > +{ > + return pte_present(pte) && pte_user(pte); > +} > + > +static inline bool pmd_user_accessible_page(struct mm_struct *mm, > + unsigned long addr, pmd_t pmd) > +{ > + return false; > +} > + > +static inline bool pud_user_accessible_page(struct mm_struct *mm, > + unsigned long addr, pud_t pud) > +{ > + return false; > +} > > extern inline pte_t pte_wrprotect(pte_t pte) { pte_val(pte) |= _PAGE_FOW; > return pte; } > extern inline pte_t pte_mkclean(pte_t pte) { pte_val(pte) &= > ~(__DIRTY_BITS); return pte; } > Hi Matt,
I tested this on a two-CPU UP2000 with PAGE_TABLE_CHECK enabled and enforced. A userspace test exercised anonymous, private file-backed, and shared mappings, together with fork/COW, mprotect(), madvise(), PTE teardown, and refault. Single-process and concurrent CPU-pinned runs completed successfully, with no page-table-check warnings, BUGs, or oopses. Tested-by: Magnus Lindholm <[email protected]> Reviewed-by: Magnus Lindholm <[email protected]> Regards, Magnus
