x86, mm: Merge alloc_low_page between 64bit and 32bit

They are almost same except 64 bit need to handle after_bootmem case.

Add mm_internal.h to make that alloc_low_page() only to be accessible
from arch/x86/mm/init*.c
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1353123563-3103-25-git-send-email-yinghai@kernel.orgSigned-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/mm/init.c

@@ -17,10 +17,44 @@
 #include <asm/proto.h>
 #include <asm/dma.h>		/* for MAX_DMA_PFN */
 
+#include "mm_internal.h"
+
 unsigned long __initdata pgt_buf_start;
 unsigned long __meminitdata pgt_buf_end;
 unsigned long __meminitdata pgt_buf_top;
 
+__ref void *alloc_low_page(void)
+{
+	unsigned long pfn;
+	void *adr;
+
+#ifdef CONFIG_X86_64
+	if (after_bootmem) {
+		adr = (void *)get_zeroed_page(GFP_ATOMIC | __GFP_NOTRACK);
+
+		return adr;
+	}
+#endif
+
+	if ((pgt_buf_end + 1) >= pgt_buf_top) {
+		unsigned long ret;
+		if (min_pfn_mapped >= max_pfn_mapped)
+			panic("alloc_low_page: ran out of memory");
+		ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT,
+					max_pfn_mapped << PAGE_SHIFT,
+					PAGE_SIZE, PAGE_SIZE);
+		if (!ret)
+			panic("alloc_low_page: can not alloc memory");
+		memblock_reserve(ret, PAGE_SIZE);
+		pfn = ret >> PAGE_SHIFT;
+	} else
+		pfn = pgt_buf_end++;
+
+	adr = __va(pfn * PAGE_SIZE);
+	clear_page(adr);
+	return adr;
+}
+
 /* need 4 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */
 #define INIT_PGT_BUF_SIZE	(5 * PAGE_SIZE)
 RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE);

arch/x86/mm/init_32.c

@@ -53,36 +53,14 @@
 #include <asm/page_types.h>
 #include <asm/init.h>
 
+#include "mm_internal.h"
+
 unsigned long highstart_pfn, highend_pfn;
 
 static noinline int do_test_wp_bit(void);
 
 bool __read_mostly __vmalloc_start_set = false;
 
-static __init void *alloc_low_page(void)
-{
-	unsigned long pfn;
-	void *adr;
-
-	if ((pgt_buf_end + 1) >= pgt_buf_top) {
-		unsigned long ret;
-		if (min_pfn_mapped >= max_pfn_mapped)
-			panic("alloc_low_page: ran out of memory");
-		ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT,
-					max_pfn_mapped << PAGE_SHIFT,
-					PAGE_SIZE, PAGE_SIZE);
-		if (!ret)
-			panic("alloc_low_page: can not alloc memory");
-		memblock_reserve(ret, PAGE_SIZE);
-		pfn = ret >> PAGE_SHIFT;
-	} else
-		pfn = pgt_buf_end++;
-
-	adr = __va(pfn * PAGE_SIZE);
-	clear_page(adr);
-	return adr;
-}
-
 /*
  * Creates a middle page table and puts a pointer to it in the
  * given global directory entry. This only returns the gd entry

arch/x86/mm/init_64.c

@@ -54,6 +54,8 @@
 #include <asm/uv/uv.h>
 #include <asm/setup.h>
 
+#include "mm_internal.h"
+
 static int __init parse_direct_gbpages_off(char *arg)
 {
 	direct_gbpages = 0;
@@ -314,36 +316,6 @@ void __init cleanup_highmap(void)
 	}
 }
 
-static __ref void *alloc_low_page(void)
-{
-	unsigned long pfn;
-	void *adr;
-
-	if (after_bootmem) {
-		adr = (void *)get_zeroed_page(GFP_ATOMIC | __GFP_NOTRACK);
-
-		return adr;
-	}
-
-	if ((pgt_buf_end + 1) >= pgt_buf_top) {
-		unsigned long ret;
-		if (min_pfn_mapped >= max_pfn_mapped)
-			panic("alloc_low_page: ran out of memory");
-		ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT,
-					max_pfn_mapped << PAGE_SHIFT,
-					PAGE_SIZE, PAGE_SIZE);
-		if (!ret)
-			panic("alloc_low_page: can not alloc memory");
-		memblock_reserve(ret, PAGE_SIZE);
-		pfn = ret >> PAGE_SHIFT;
-	} else
-		pfn = pgt_buf_end++;
-
-	adr = __va(pfn * PAGE_SIZE);
-	clear_page(adr);
-	return adr;
-}
-
 static unsigned long __meminit
 phys_pte_init(pte_t *pte_page, unsigned long addr, unsigned long end,
 	      pgprot_t prot)

arch/x86/mm/mm_internal.h

+#ifndef __X86_MM_INTERNAL_H
+#define __X86_MM_INTERNAL_H
+
+void *alloc_low_page(void);
+
+#endif	/* __X86_MM_INTERNAL_H */