[PATCH v2 13/22] alpha: add ARCH_SUPPORTS_PAGE_TABLE_CHECK support
From: Matt Turner <mattst88@gmail.com>
Date: 2026-09-05 19:29:56
Also in:
linux-alpha, linux-hardening, lkml
Subsystem:
alpha port, the rest · Maintainers:
Richard Henderson, Matt Turner, Magnus Lindholm, Linus Torvalds
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 <mattst88@gmail.com>
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; }
--
2.54.0