mem: get page table entries for vaddr

Add APIs to return the virtual addresses of
page table entries that map a given virtual address.

Signed-off-by: Daniele Ahmed <ahmeddan amazon c;0m >

include/arch/x86/pagetable.h

@@ -237,6 +237,33 @@ static inline pte_t *get_l1_table(const void *va) {
     return INVALID_PGENTRY(l1e) ? NULL : mfn_to_virt_kern(l1e->mfn);
 }
 
+/* Return the virtual address of the PT entry mapping this virtual address.
+ * The entry is assumed to be mapped
+ */
+static inline pgentry_t *get_pte(const void *va) {
+    pte_t *l1t = get_l1_table(va);
+    pte_t *l1e = l1_table_entry(l1t, va);
+    return &(l1e->entry);
+}
+
+/* Return the virtual address of the PD entry mapping this virtual address.
+ * The entry is assumed to be mapped
+ */
+static inline pgentry_t *get_pde(const void *va) {
+    pde_t *l2t = get_l2_table(va);
+    pde_t *l2e = l2_table_entry(l2t, va);
+    return &(l2e->entry);
+}
+
+/* Return the virtual address of the PDP entry mapping this virtual address.
+ * The entry is assumed to be mapped
+ */
+static inline pgentry_t *get_pdpe(const void *va) {
+    pdpe_t *l3t = get_l3_table(va);
+    pdpe_t *l3e = l3_table_entry(l3t, va);
+    return &(l3e->entry);
+}
+
 static inline void set_pgentry(pgentry_t *e, mfn_t mfn, unsigned long flags) {
     *e = pgentry_from_mfn(mfn, flags);
     barrier();