v4.19.13 snapshot.
diff --git a/arch/x86/mm/pat_internal.h b/arch/x86/mm/pat_internal.h
new file mode 100644
index 0000000..eeb5cae
--- /dev/null
+++ b/arch/x86/mm/pat_internal.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PAT_INTERNAL_H_
+#define __PAT_INTERNAL_H_
+
+extern int pat_debug_enable;
+
+#define dprintk(fmt, arg...) \
+ do { if (pat_debug_enable) pr_info("x86/PAT: " fmt, ##arg); } while (0)
+
+struct memtype {
+ u64 start;
+ u64 end;
+ u64 subtree_max_end;
+ enum page_cache_mode type;
+ struct rb_node rb;
+};
+
+static inline char *cattr_name(enum page_cache_mode pcm)
+{
+ switch (pcm) {
+ case _PAGE_CACHE_MODE_UC: return "uncached";
+ case _PAGE_CACHE_MODE_UC_MINUS: return "uncached-minus";
+ case _PAGE_CACHE_MODE_WB: return "write-back";
+ case _PAGE_CACHE_MODE_WC: return "write-combining";
+ case _PAGE_CACHE_MODE_WT: return "write-through";
+ case _PAGE_CACHE_MODE_WP: return "write-protected";
+ default: return "broken";
+ }
+}
+
+#ifdef CONFIG_X86_PAT
+extern int rbt_memtype_check_insert(struct memtype *new,
+ enum page_cache_mode *new_type);
+extern struct memtype *rbt_memtype_erase(u64 start, u64 end);
+extern struct memtype *rbt_memtype_lookup(u64 addr);
+extern int rbt_memtype_copy_nth_element(struct memtype *out, loff_t pos);
+#else
+static inline int rbt_memtype_check_insert(struct memtype *new,
+ enum page_cache_mode *new_type)
+{ return 0; }
+static inline struct memtype *rbt_memtype_erase(u64 start, u64 end)
+{ return NULL; }
+static inline struct memtype *rbt_memtype_lookup(u64 addr)
+{ return NULL; }
+static inline int rbt_memtype_copy_nth_element(struct memtype *out, loff_t pos)
+{ return 0; }
+#endif
+
+#endif /* __PAT_INTERNAL_H_ */