diff --git a/lib/asm-generic/memory_areas.h b/lib/asm-generic/memory_areas.h
index 927baa7..3074afe 100644
--- a/lib/asm-generic/memory_areas.h
+++ b/lib/asm-generic/memory_areas.h
@@ -1,11 +1,10 @@
-#ifndef MEMORY_AREAS_H
-#define MEMORY_AREAS_H
+#ifndef __ASM_GENERIC_MEMORY_AREAS_H__
+#define __ASM_GENERIC_MEMORY_AREAS_H__
 
 #define AREA_NORMAL_PFN 0
 #define AREA_NORMAL_NUMBER 0
-#define AREA_NORMAL 1
+#define AREA_NORMAL (1 << AREA_NORMAL_NUMBER)
 
-#define AREA_ANY -1
-#define AREA_ANY_NUMBER 0xff
+#define MAX_AREAS 1
 
 #endif
diff --git a/lib/arm/asm/memory_areas.h b/lib/arm/asm/memory_areas.h
index 927baa7..c723310 100644
--- a/lib/arm/asm/memory_areas.h
+++ b/lib/arm/asm/memory_areas.h
@@ -1,11 +1,6 @@
-#ifndef MEMORY_AREAS_H
-#define MEMORY_AREAS_H
+#ifndef _ASMARM_MEMORY_AREAS_H_
+#define _ASMARM_MEMORY_AREAS_H_
 
-#define AREA_NORMAL_PFN 0
-#define AREA_NORMAL_NUMBER 0
-#define AREA_NORMAL 1
-
-#define AREA_ANY -1
-#define AREA_ANY_NUMBER 0xff
+#include <asm-generic/memory_areas.h>
 
 #endif
diff --git a/lib/arm64/asm/memory_areas.h b/lib/arm64/asm/memory_areas.h
index 927baa7..18e8ca8 100644
--- a/lib/arm64/asm/memory_areas.h
+++ b/lib/arm64/asm/memory_areas.h
@@ -1,11 +1,6 @@
-#ifndef MEMORY_AREAS_H
-#define MEMORY_AREAS_H
+#ifndef _ASMARM64_MEMORY_AREAS_H_
+#define _ASMARM64_MEMORY_AREAS_H_
 
-#define AREA_NORMAL_PFN 0
-#define AREA_NORMAL_NUMBER 0
-#define AREA_NORMAL 1
-
-#define AREA_ANY -1
-#define AREA_ANY_NUMBER 0xff
+#include <asm-generic/memory_areas.h>
 
 #endif
diff --git a/lib/powerpc/asm/memory_areas.h b/lib/powerpc/asm/memory_areas.h
index 927baa7..76d1738 100644
--- a/lib/powerpc/asm/memory_areas.h
+++ b/lib/powerpc/asm/memory_areas.h
@@ -1,11 +1,6 @@
-#ifndef MEMORY_AREAS_H
-#define MEMORY_AREAS_H
+#ifndef _ASMPOWERPC_MEMORY_AREAS_H_
+#define _ASMPOWERPC_MEMORY_AREAS_H_
 
-#define AREA_NORMAL_PFN 0
-#define AREA_NORMAL_NUMBER 0
-#define AREA_NORMAL 1
-
-#define AREA_ANY -1
-#define AREA_ANY_NUMBER 0xff
+#include <asm-generic/memory_areas.h>
 
 #endif
diff --git a/lib/ppc64/asm/memory_areas.h b/lib/ppc64/asm/memory_areas.h
index 927baa7..b9fd46b 100644
--- a/lib/ppc64/asm/memory_areas.h
+++ b/lib/ppc64/asm/memory_areas.h
@@ -1,11 +1,6 @@
-#ifndef MEMORY_AREAS_H
-#define MEMORY_AREAS_H
+#ifndef _ASMPPC64_MEMORY_AREAS_H_
+#define _ASMPPC64_MEMORY_AREAS_H_
 
-#define AREA_NORMAL_PFN 0
-#define AREA_NORMAL_NUMBER 0
-#define AREA_NORMAL 1
-
-#define AREA_ANY -1
-#define AREA_ANY_NUMBER 0xff
+#include <asm-generic/memory_areas.h>
 
 #endif
diff --git a/lib/s390x/asm/memory_areas.h b/lib/s390x/asm/memory_areas.h
index 4856a27..827bfb3 100644
--- a/lib/s390x/asm/memory_areas.h
+++ b/lib/s390x/asm/memory_areas.h
@@ -1,16 +1,15 @@
-#ifndef MEMORY_AREAS_H
-#define MEMORY_AREAS_H
+#ifndef _ASMS390X_MEMORY_AREAS_H_
+#define _ASMS390X_MEMORY_AREAS_H_
 
-#define AREA_NORMAL_PFN BIT(31-12)
+#define AREA_NORMAL_PFN (1 << 19)
 #define AREA_NORMAL_NUMBER 0
-#define AREA_NORMAL 1
+#define AREA_NORMAL (1 << AREA_NORMAL_NUMBER)
 
 #define AREA_LOW_PFN 0
 #define AREA_LOW_NUMBER 1
-#define AREA_LOW 2
+#define AREA_LOW (1 << AREA_LOW_NUMBER)
 
-#define AREA_ANY -1
-#define AREA_ANY_NUMBER 0xff
+#define MAX_AREAS 2
 
 #define AREA_DMA31 AREA_LOW
 
diff --git a/lib/x86/asm/memory_areas.h b/lib/x86/asm/memory_areas.h
index 952f5bd..e84016f 100644
--- a/lib/x86/asm/memory_areas.h
+++ b/lib/x86/asm/memory_areas.h
@@ -1,21 +1,26 @@
-#ifndef MEMORY_AREAS_H
-#define MEMORY_AREAS_H
+#ifndef _ASM_X86_MEMORY_AREAS_H_
+#define _ASM_X86_MEMORY_AREAS_H_
 
 #define AREA_NORMAL_PFN BIT(36-12)
 #define AREA_NORMAL_NUMBER 0
-#define AREA_NORMAL 1
+#define AREA_NORMAL (1 << AREA_NORMAL_NUMBER)
 
-#define AREA_PAE_HIGH_PFN BIT(32-12)
-#define AREA_PAE_HIGH_NUMBER 1
-#define AREA_PAE_HIGH 2
+#define AREA_HIGH_PFN BIT(32-12)
+#define AREA_HIGH_NUMBER 1
+#define AREA_HIGH (1 << AREA_HIGH_NUMBER)
 
-#define AREA_LOW_PFN 0
+#define AREA_LOW_PFN BIT(24-12)
 #define AREA_LOW_NUMBER 2
-#define AREA_LOW 4
+#define AREA_LOW (1 << AREA_LOW_NUMBER)
 
-#define AREA_PAE (AREA_PAE | AREA_LOW)
+#define AREA_LOWEST_PFN 0
+#define AREA_LOWEST_NUMBER 3
+#define AREA_LOWEST (1 << AREA_LOWEST_NUMBER)
 
-#define AREA_ANY -1
-#define AREA_ANY_NUMBER 0xff
+#define MAX_AREAS 4
+
+#define AREA_DMA24 AREA_LOWEST
+#define AREA_DMA32 (AREA_LOWEST | AREA_LOW)
+#define AREA_PAE36 (AREA_LOWEST | AREA_LOW | AREA_HIGH)
 
 #endif
diff --git a/lib/alloc_page.h b/lib/alloc_page.h
index 816ff5d..b6aace5 100644
--- a/lib/alloc_page.h
+++ b/lib/alloc_page.h
@@ -10,6 +10,9 @@
 
 #include <asm/memory_areas.h>
 
+#define AREA_ANY -1
+#define AREA_ANY_NUMBER 0xff
+
 /* Returns true if the page allocator has been initialized */
 bool page_alloc_initialized(void);
 
diff --git a/lib/alloc_page.c b/lib/alloc_page.c
index 685ab1e..ed0ff02 100644
--- a/lib/alloc_page.c
+++ b/lib/alloc_page.c
@@ -19,8 +19,6 @@
 #define NLISTS ((BITS_PER_LONG) - (PAGE_SHIFT))
 #define PFN(x) ((uintptr_t)(x) >> PAGE_SHIFT)
 
-#define MAX_AREAS	6
-
 #define ORDER_MASK	0x3f
 #define ALLOC_MASK	0x40
 #define SPECIAL_MASK	0x80
@@ -509,7 +507,7 @@ void page_alloc_init_area(u8 n, uintptr_t base_pfn, uintptr_t top_pfn)
 		return;
 	}
 #ifdef AREA_HIGH_PFN
-	__page_alloc_init_area(AREA_HIGH_NUMBER, AREA_HIGH_PFN), base_pfn, &top_pfn);
+	__page_alloc_init_area(AREA_HIGH_NUMBER, AREA_HIGH_PFN, base_pfn, &top_pfn);
 #endif
 	__page_alloc_init_area(AREA_NORMAL_NUMBER, AREA_NORMAL_PFN, base_pfn, &top_pfn);
 #ifdef AREA_LOW_PFN
