arm64: pgtable: Warn unexpected pmdp_test_and_clear_young()

Young bit operation on PMD table entry is only supported if
FEAT_HAFT enabled system wide. Add a warning for notifying
the misbehaviour.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20241102104235.62560-6-yangyicong@huawei.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 5182feabd943f61a3019f0899b7dce5160586e83..160ca503c99f4efdca24509e96552cdbb761862a 100644 (file)
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1265,6 +1265,8 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
                                            unsigned long address,
                                            pmd_t *pmdp)
 {
+       /* Operation applies to PMD table entry only if FEAT_HAFT is enabled */
+       VM_WARN_ON(pmd_table(READ_ONCE(*pmdp)) && !system_supports_haft());
        return __ptep_test_and_clear_young(vma, address, (pte_t *)pmdp);
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */