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-rw-r--r--arch/x86/mm/pageattr.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index dfaf2e0f5f8f..536ea2fb6e33 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -384,6 +384,26 @@ static pte_t *_lookup_address_cpa(struct cpa_data *cpa, unsigned long address,
}
/*
+ * Lookup the PMD entry for a virtual address. Return a pointer to the entry
+ * or NULL if not present.
+ */
+pmd_t *lookup_pmd_address(unsigned long address)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+
+ pgd = pgd_offset_k(address);
+ if (pgd_none(*pgd))
+ return NULL;
+
+ pud = pud_offset(pgd, address);
+ if (pud_none(*pud) || pud_large(*pud) || !pud_present(*pud))
+ return NULL;
+
+ return pmd_offset(pud, address);
+}
+
+/*
* This is necessary because __pa() does not work on some
* kinds of memory, like vmalloc() or the alloc_remap()
* areas on 32-bit NUMA systems. The percpu areas can