[PATCH v2 07/15] riscv/mm: preserve Svnapot leaf-size semantics for page-table consumers

[Yunhui Cui]

Svnapot keeps a folded 64KB mapping encoded in the page table, while the
public PTE helpers may expose a logical per-page sub-PTE view to generic
MM users. That logical view is suitable for leaf-style PTE consumers, but
it must not change the effective leaf size reported for the mapping.

Use the original page-table entry for leaf-size queries, so page-table
consumers continue to observe the Svnapot leaf size instead of incorrectly
treating a folded mapping as PAGE_SIZE entries.

Signed-off-by: Yunhui Cui <cuiyunhui at bytedance.com>
---
 arch/riscv/include/asm/pgtable.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index da7ffea0dcd98..e4b9c05014c00 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -580,6 +580,17 @@ static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
 					napot_cont_size(napot_cont_order(pte)) :\
 					PAGE_SIZE)
 
+#define __ptep_leaf_size __ptep_leaf_size
+static inline unsigned long __ptep_leaf_size(pmd_t pmd, pte_t *ptep, pte_t pte)
+{
+	pte_t raw_pte = READ_ONCE(*ptep);
+
+	if (pte_present_napot(raw_pte))
+		return pte_leaf_size(raw_pte);
+
+	return PAGE_SIZE;
+}
+
 void __napotpte_try_fold(struct mm_struct *mm, unsigned long addr,
 			 pte_t *ptep, pte_t pte);
 void __napotpte_try_unfold(struct mm_struct *mm, unsigned long addr,
-- 
2.39.5