arch/arm/include/asm/memory.h - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  *  arch/arm/include/asm/memory.h
  *
  *  Copyright (C) 2000-2002 Russell King
  *  modification for nommu, Hyok S. Choi, 2004
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  *  Note: this file should not be included by non-asm/.h files
  */
 #ifndef __ASM_ARM_MEMORY_H
 #define __ASM_ARM_MEMORY_H

 #include <linux/compiler.h>
 #include <linux/const.h>
 #include <linux/types.h>
 #include <linux/sizes.h>

 #ifdef CONFIG_NEED_MACH_MEMORY_H
 #include <mach/memory.h>
 #endif

 /*
  * Allow for constants defined here to be used from assembly code
  * by prepending the UL suffix only with actual C code compilation.
  */
 #define UL(x) _AC(x, UL)

 /* PAGE_OFFSET - the virtual address of the start of the kernel image */
 #define PAGE_OFFSET		UL(CONFIG_PAGE_OFFSET)

 #ifdef CONFIG_MMU

 /*
  * TASK_SIZE - the maximum size of a user space task.
  * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area
  */
 #define TASK_SIZE		(UL(CONFIG_PAGE_OFFSET) - UL(SZ_16M))
 #define TASK_UNMAPPED_BASE	ALIGN(TASK_SIZE / 3, SZ_16M)

 /*
  * The maximum size of a 26-bit user space task.
  */
 #define TASK_SIZE_26		(UL(1) << 26)

 /*
  * The module space lives between the addresses given by TASK_SIZE
  * and PAGE_OFFSET - it must be within 32MB of the kernel text.
  */
 #ifndef CONFIG_THUMB2_KERNEL
 #define MODULES_VADDR		(PAGE_OFFSET - SZ_16M)
 #else
 /* smaller range for Thumb-2 symbols relocation (2^24)*/
 #define MODULES_VADDR		(PAGE_OFFSET - SZ_8M)
 #endif

 #if TASK_SIZE > MODULES_VADDR
 #error Top of user space clashes with start of module space
 #endif

 /*
  * The highmem pkmap virtual space shares the end of the module area.
  */
 #ifdef CONFIG_HIGHMEM
 #define MODULES_END		(PAGE_OFFSET - PMD_SIZE)
 #else
 #define MODULES_END		(PAGE_OFFSET)
 #endif

 /*
  * The XIP kernel gets mapped at the bottom of the module vm area.
  * Since we use sections to map it, this macro replaces the physical address
  * with its virtual address while keeping offset from the base section.
  */
 #define XIP_VIRT_ADDR(physaddr)  (MODULES_VADDR + ((physaddr) & 0x000fffff))

 #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
 /*
  * Allow 16MB-aligned ioremap pages
  */
 #define IOREMAP_MAX_ORDER	24
 #endif

 #else /* CONFIG_MMU */

 /*
  * The limitation of user task size can grow up to the end of free ram region.
  * It is difficult to define and perhaps will never meet the original meaning
  * of this define that was meant to.
  * Fortunately, there is no reference for this in noMMU mode, for now.
  */
 #define TASK_SIZE		UL(0xffffffff)

 #ifndef TASK_UNMAPPED_BASE
 #define TASK_UNMAPPED_BASE	UL(0x00000000)
 #endif

 #ifndef END_MEM
 #define END_MEM     		(UL(CONFIG_DRAM_BASE) + CONFIG_DRAM_SIZE)
 #endif

 /*
  * The module can be at any place in ram in nommu mode.
  */
 #define MODULES_END		(END_MEM)
 #define MODULES_VADDR		PAGE_OFFSET

 #define XIP_VIRT_ADDR(physaddr)  (physaddr)

 #endif /* !CONFIG_MMU */

 /*
  * We fix the TCM memories max 32 KiB ITCM resp DTCM at these
  * locations
  */
 #ifdef CONFIG_HAVE_TCM
 #define ITCM_OFFSET	UL(0xfffe0000)
 #define DTCM_OFFSET	UL(0xfffe8000)
 #endif

 /*
  * Convert a page to/from a physical address
  */
 #define page_to_phys(page)	(__pfn_to_phys(page_to_pfn(page)))
 #define phys_to_page(phys)	(pfn_to_page(__phys_to_pfn(phys)))

 /*
  * PLAT_PHYS_OFFSET is the offset (from zero) of the start of physical
  * memory.  This is used for XIP and NoMMU kernels, and on platforms that don't
  * have CONFIG_ARM_PATCH_PHYS_VIRT. Assembly code must always use
  * PLAT_PHYS_OFFSET and not PHYS_OFFSET.
  */
 #define PLAT_PHYS_OFFSET	UL(CONFIG_PHYS_OFFSET)

 #ifdef CONFIG_XIP_KERNEL
 /*
  * When referencing data in RAM from the XIP region in a relative manner
  * with the MMU off, we need the relative offset between the two physical
  * addresses.  The macro below achieves this, which is:
  *    __pa(v_data) - __xip_pa(v_text)
  */
 #define PHYS_RELATIVE(v_data, v_text) \
 	(((v_data) - PAGE_OFFSET + PLAT_PHYS_OFFSET) - \
 	 ((v_text) - XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR) + \
           CONFIG_XIP_PHYS_ADDR))
 #else
 #define PHYS_RELATIVE(v_data, v_text) ((v_data) - (v_text))
 #endif

 #ifndef __ASSEMBLY__

 /*
  * Physical vs virtual RAM address space conversion.  These are
  * private definitions which should NOT be used outside memory.h
  * files.  Use virt_to_phys/phys_to_virt/__pa/__va instead.
  *
  * PFNs are used to describe any physical page; this means
  * PFN 0 == physical address 0.
  */
 #if defined(__virt_to_phys)
 #define PHYS_OFFSET	PLAT_PHYS_OFFSET
 #define PHYS_PFN_OFFSET	((unsigned long)(PHYS_OFFSET >> PAGE_SHIFT))

 #define virt_to_pfn(kaddr) (__pa(kaddr) >> PAGE_SHIFT)

 #elif defined(CONFIG_ARM_PATCH_PHYS_VIRT)

 /*
  * Constants used to force the right instruction encodings and shifts
  * so that all we need to do is modify the 8-bit constant field.
  */
 #define __PV_BITS_31_24	0x81000000
 #define __PV_BITS_7_0	0x81

 extern unsigned long __pv_phys_pfn_offset;
 extern u64 __pv_offset;
 extern void fixup_pv_table(const void *, unsigned long);
 extern const void *__pv_table_begin, *__pv_table_end;

 #define PHYS_OFFSET	((phys_addr_t)__pv_phys_pfn_offset << PAGE_SHIFT)
 #define PHYS_PFN_OFFSET	(__pv_phys_pfn_offset)

 #define virt_to_pfn(kaddr) \
 	((((unsigned long)(kaddr) - PAGE_OFFSET) >> PAGE_SHIFT) + \
 	 PHYS_PFN_OFFSET)

 #define __pv_stub(from,to,instr,type)			\
 	__asm__("@ __pv_stub\n"				\
 	"1:	" instr "	%0, %1, %2\n"		\
 	"	.pushsection .pv_table,\"a\"\n"		\
 	"	.long	1b\n"				\
 	"	.popsection\n"				\
 	: "=r" (to)					\
 	: "r" (from), "I" (type))

 #define __pv_stub_mov_hi(t)				\
 	__asm__ volatile("@ __pv_stub_mov\n"		\
 	"1:	mov	%R0, %1\n"			\
 	"	.pushsection .pv_table,\"a\"\n"		\
 	"	.long	1b\n"				\
 	"	.popsection\n"				\
 	: "=r" (t)					\
 	: "I" (__PV_BITS_7_0))

 #define __pv_add_carry_stub(x, y)			\
 	__asm__ volatile("@ __pv_add_carry_stub\n"	\
 	"1:	adds	%Q0, %1, %2\n"			\
 	"	adc	%R0, %R0, #0\n"			\
 	"	.pushsection .pv_table,\"a\"\n"		\
 	"	.long	1b\n"				\
 	"	.popsection\n"				\
 	: "+r" (y)					\
 	: "r" (x), "I" (__PV_BITS_31_24)		\
 	: "cc")

 static inline phys_addr_t __virt_to_phys(unsigned long x)
 {
 	phys_addr_t t;

 	if (sizeof(phys_addr_t) == 4) {
 		__pv_stub(x, t, "add", __PV_BITS_31_24);
 	} else {
 		__pv_stub_mov_hi(t);
 		__pv_add_carry_stub(x, t);
 	}
 	return t;
 }

 static inline unsigned long __phys_to_virt(phys_addr_t x)
 {
 	unsigned long t;

 	/*
 	 * 'unsigned long' cast discard upper word when
 	 * phys_addr_t is 64 bit, and makes sure that inline
 	 * assembler expression receives 32 bit argument
 	 * in place where 'r' 32 bit operand is expected.
 	 */
 	__pv_stub((unsigned long) x, t, "sub", __PV_BITS_31_24);
 	return t;
 }

 #else

 #define PHYS_OFFSET	PLAT_PHYS_OFFSET
 #define PHYS_PFN_OFFSET	((unsigned long)(PHYS_OFFSET >> PAGE_SHIFT))

 static inline phys_addr_t __virt_to_phys(unsigned long x)
 {
 	return (phys_addr_t)x - PAGE_OFFSET + PHYS_OFFSET;
 }

 static inline unsigned long __phys_to_virt(phys_addr_t x)
 {
 	return x - PHYS_OFFSET + PAGE_OFFSET;
 }

 #define virt_to_pfn(kaddr) \
 	((((unsigned long)(kaddr) - PAGE_OFFSET) >> PAGE_SHIFT) + \
 	 PHYS_PFN_OFFSET)

 #endif

 /*
  * These are *only* valid on the kernel direct mapped RAM memory.
  * Note: Drivers should NOT use these.  They are the wrong
  * translation for translating DMA addresses.  Use the driver
  * DMA support - see dma-mapping.h.
  */
 #define virt_to_phys virt_to_phys
 static inline phys_addr_t virt_to_phys(const volatile void *x)
 {
 	return __virt_to_phys((unsigned long)(x));
 }

 #define phys_to_virt phys_to_virt
 static inline void *phys_to_virt(phys_addr_t x)
 {
 	return (void *)__phys_to_virt(x);
 }

 /*
  * Drivers should NOT use these either.
  */
 #define __pa(x)			__virt_to_phys((unsigned long)(x))
 #define __va(x)			((void *)__phys_to_virt((phys_addr_t)(x)))
 #define pfn_to_kaddr(pfn)	__va((phys_addr_t)(pfn) << PAGE_SHIFT)

 extern unsigned long (*arch_virt_to_idmap)(unsigned long x);

 /*
  * These are for systems that have a hardware interconnect supported alias of
  * physical memory for idmap purposes.  Most cases should leave these
  * untouched.  Note: this can only return addresses less than 4GiB.
  */
 static inline unsigned long __virt_to_idmap(unsigned long x)
 {
 	if (IS_ENABLED(CONFIG_MMU) && arch_virt_to_idmap)
 		return arch_virt_to_idmap(x);
 	else
 		return __virt_to_phys(x);
 }

 #define virt_to_idmap(x)	__virt_to_idmap((unsigned long)(x))

 /*
  * Virtual <-> DMA view memory address translations
  * Again, these are *only* valid on the kernel direct mapped RAM
  * memory.  Use of these is *deprecated* (and that doesn't mean
  * use the __ prefixed forms instead.)  See dma-mapping.h.
  */
 #ifndef __virt_to_bus
 #define __virt_to_bus	__virt_to_phys
 #define __bus_to_virt	__phys_to_virt
 #define __pfn_to_bus(x)	__pfn_to_phys(x)
 #define __bus_to_pfn(x)	__phys_to_pfn(x)
 #endif

 /*
  * Conversion between a struct page and a physical address.
  *
  *  page_to_pfn(page)	convert a struct page * to a PFN number
  *  pfn_to_page(pfn)	convert a _valid_ PFN number to struct page *
  *
  *  virt_to_page(k)	convert a _valid_ virtual address to struct page *
  *  virt_addr_valid(k)	indicates whether a virtual address is valid
  */
 #define ARCH_PFN_OFFSET		PHYS_PFN_OFFSET

 #define virt_to_page(kaddr)	pfn_to_page(virt_to_pfn(kaddr))
 #define virt_addr_valid(kaddr)	(((unsigned long)(kaddr) >= PAGE_OFFSET && (unsigned long)(kaddr) < (unsigned long)high_memory) \
 					&& pfn_valid(virt_to_pfn(kaddr)))

 #endif

 #include <asm-generic/memory_model.h>

 #endif
	/*
	* arch/arm/include/asm/memory.h
	*
	* Copyright (C) 2000-2002 Russell King
	* modification for nommu, Hyok S. Choi, 2004
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* Note: this file should not be included by non-asm/.h files
	*/
	#ifndef __ASM_ARM_MEMORY_H
	#define __ASM_ARM_MEMORY_H

	#include <linux/compiler.h>
	#include <linux/const.h>
	#include <linux/types.h>
	#include <linux/sizes.h>

	#ifdef CONFIG_NEED_MACH_MEMORY_H
	#include <mach/memory.h>
	#endif

	/*
	* Allow for constants defined here to be used from assembly code
	* by prepending the UL suffix only with actual C code compilation.
	*/
	#define UL(x) _AC(x, UL)

	/* PAGE_OFFSET - the virtual address of the start of the kernel image */
	#define PAGE_OFFSET UL(CONFIG_PAGE_OFFSET)

	#ifdef CONFIG_MMU

	/*
	* TASK_SIZE - the maximum size of a user space task.
	* TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area
	*/
	#define TASK_SIZE (UL(CONFIG_PAGE_OFFSET) - UL(SZ_16M))
	#define TASK_UNMAPPED_BASE ALIGN(TASK_SIZE / 3, SZ_16M)

	/*
	* The maximum size of a 26-bit user space task.
	*/
	#define TASK_SIZE_26 (UL(1) << 26)

	/*
	* The module space lives between the addresses given by TASK_SIZE
	* and PAGE_OFFSET - it must be within 32MB of the kernel text.
	*/
	#ifndef CONFIG_THUMB2_KERNEL
	#define MODULES_VADDR (PAGE_OFFSET - SZ_16M)
	#else
	/* smaller range for Thumb-2 symbols relocation (2^24)*/
	#define MODULES_VADDR (PAGE_OFFSET - SZ_8M)
	#endif

	#if TASK_SIZE > MODULES_VADDR
	#error Top of user space clashes with start of module space
	#endif

	/*
	* The highmem pkmap virtual space shares the end of the module area.
	*/
	#ifdef CONFIG_HIGHMEM
	#define MODULES_END (PAGE_OFFSET - PMD_SIZE)
	#else
	#define MODULES_END (PAGE_OFFSET)
	#endif

	/*
	* The XIP kernel gets mapped at the bottom of the module vm area.
	* Since we use sections to map it, this macro replaces the physical address
	* with its virtual address while keeping offset from the base section.
	*/
	#define XIP_VIRT_ADDR(physaddr) (MODULES_VADDR + ((physaddr) & 0x000fffff))

	#if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
	/*
	* Allow 16MB-aligned ioremap pages
	*/
	#define IOREMAP_MAX_ORDER 24
	#endif

	#else /* CONFIG_MMU */

	/*
	* The limitation of user task size can grow up to the end of free ram region.
	* It is difficult to define and perhaps will never meet the original meaning
	* of this define that was meant to.
	* Fortunately, there is no reference for this in noMMU mode, for now.
	*/
	#define TASK_SIZE UL(0xffffffff)

	#ifndef TASK_UNMAPPED_BASE
	#define TASK_UNMAPPED_BASE UL(0x00000000)
	#endif

	#ifndef END_MEM
	#define END_MEM (UL(CONFIG_DRAM_BASE) + CONFIG_DRAM_SIZE)
	#endif

	/*
	* The module can be at any place in ram in nommu mode.
	*/
	#define MODULES_END (END_MEM)
	#define MODULES_VADDR PAGE_OFFSET

	#define XIP_VIRT_ADDR(physaddr) (physaddr)

	#endif /* !CONFIG_MMU */

	/*
	* We fix the TCM memories max 32 KiB ITCM resp DTCM at these
	* locations
	*/
	#ifdef CONFIG_HAVE_TCM
	#define ITCM_OFFSET UL(0xfffe0000)
	#define DTCM_OFFSET UL(0xfffe8000)
	#endif

	/*
	* Convert a page to/from a physical address
	*/
	#define page_to_phys(page) (__pfn_to_phys(page_to_pfn(page)))
	#define phys_to_page(phys) (pfn_to_page(__phys_to_pfn(phys)))

	/*
	* PLAT_PHYS_OFFSET is the offset (from zero) of the start of physical
	* memory. This is used for XIP and NoMMU kernels, and on platforms that don't
	* have CONFIG_ARM_PATCH_PHYS_VIRT. Assembly code must always use
	* PLAT_PHYS_OFFSET and not PHYS_OFFSET.
	*/
	#define PLAT_PHYS_OFFSET UL(CONFIG_PHYS_OFFSET)

	#ifdef CONFIG_XIP_KERNEL
	/*
	* When referencing data in RAM from the XIP region in a relative manner
	* with the MMU off, we need the relative offset between the two physical
	* addresses. The macro below achieves this, which is:
	* __pa(v_data) - __xip_pa(v_text)
	*/
	#define PHYS_RELATIVE(v_data, v_text) \
	(((v_data) - PAGE_OFFSET + PLAT_PHYS_OFFSET) - \
	((v_text) - XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR) + \
	CONFIG_XIP_PHYS_ADDR))
	#else
	#define PHYS_RELATIVE(v_data, v_text) ((v_data) - (v_text))
	#endif

	#ifndef __ASSEMBLY__

	/*
	* Physical vs virtual RAM address space conversion. These are
	* private definitions which should NOT be used outside memory.h
	* files. Use virt_to_phys/phys_to_virt/__pa/__va instead.
	*
	* PFNs are used to describe any physical page; this means
	* PFN 0 == physical address 0.
	*/
	#if defined(__virt_to_phys)
	#define PHYS_OFFSET PLAT_PHYS_OFFSET
	#define PHYS_PFN_OFFSET ((unsigned long)(PHYS_OFFSET >> PAGE_SHIFT))

	#define virt_to_pfn(kaddr) (__pa(kaddr) >> PAGE_SHIFT)

	#elif defined(CONFIG_ARM_PATCH_PHYS_VIRT)

	/*
	* Constants used to force the right instruction encodings and shifts
	* so that all we need to do is modify the 8-bit constant field.
	*/
	#define __PV_BITS_31_24 0x81000000
	#define __PV_BITS_7_0 0x81

	extern unsigned long __pv_phys_pfn_offset;
	extern u64 __pv_offset;
	extern void fixup_pv_table(const void *, unsigned long);
	extern const void __pv_table_begin, __pv_table_end;

	#define PHYS_OFFSET ((phys_addr_t)__pv_phys_pfn_offset << PAGE_SHIFT)
	#define PHYS_PFN_OFFSET (__pv_phys_pfn_offset)

	#define virt_to_pfn(kaddr) \
	((((unsigned long)(kaddr) - PAGE_OFFSET) >> PAGE_SHIFT) + \
	PHYS_PFN_OFFSET)

	#define __pv_stub(from,to,instr,type) \
	__asm__("@ __pv_stub\n" \
	"1: " instr " %0, %1, %2\n" \
	" .pushsection .pv_table,\"a\"\n" \
	" .long 1b\n" \
	" .popsection\n" \
	: "=r" (to) \
	: "r" (from), "I" (type))

	#define __pv_stub_mov_hi(t) \
	__asm__ volatile("@ __pv_stub_mov\n" \
	"1: mov %R0, %1\n" \
	" .pushsection .pv_table,\"a\"\n" \
	" .long 1b\n" \
	" .popsection\n" \
	: "=r" (t) \
	: "I" (__PV_BITS_7_0))

	#define __pv_add_carry_stub(x, y) \
	__asm__ volatile("@ __pv_add_carry_stub\n" \
	"1: adds %Q0, %1, %2\n" \
	" adc %R0, %R0, #0\n" \
	" .pushsection .pv_table,\"a\"\n" \
	" .long 1b\n" \
	" .popsection\n" \
	: "+r" (y) \
	: "r" (x), "I" (__PV_BITS_31_24) \
	: "cc")

	static inline phys_addr_t __virt_to_phys(unsigned long x)
	{
	phys_addr_t t;

	if (sizeof(phys_addr_t) == 4) {
	__pv_stub(x, t, "add", __PV_BITS_31_24);
	} else {
	__pv_stub_mov_hi(t);
	__pv_add_carry_stub(x, t);
	}
	return t;
	}

	static inline unsigned long __phys_to_virt(phys_addr_t x)
	{
	unsigned long t;

	/*
	* 'unsigned long' cast discard upper word when
	* phys_addr_t is 64 bit, and makes sure that inline
	* assembler expression receives 32 bit argument
	* in place where 'r' 32 bit operand is expected.
	*/
	__pv_stub((unsigned long) x, t, "sub", __PV_BITS_31_24);
	return t;
	}

	#else

	#define PHYS_OFFSET PLAT_PHYS_OFFSET
	#define PHYS_PFN_OFFSET ((unsigned long)(PHYS_OFFSET >> PAGE_SHIFT))

	static inline phys_addr_t __virt_to_phys(unsigned long x)
	{
	return (phys_addr_t)x - PAGE_OFFSET + PHYS_OFFSET;
	}

	static inline unsigned long __phys_to_virt(phys_addr_t x)
	{
	return x - PHYS_OFFSET + PAGE_OFFSET;
	}

	#define virt_to_pfn(kaddr) \
	((((unsigned long)(kaddr) - PAGE_OFFSET) >> PAGE_SHIFT) + \
	PHYS_PFN_OFFSET)

	#endif

	/*
	* These are only valid on the kernel direct mapped RAM memory.
	* Note: Drivers should NOT use these. They are the wrong
	* translation for translating DMA addresses. Use the driver
	* DMA support - see dma-mapping.h.
	*/
	#define virt_to_phys virt_to_phys
	static inline phys_addr_t virt_to_phys(const volatile void *x)
	{
	return __virt_to_phys((unsigned long)(x));
	}

	#define phys_to_virt phys_to_virt
	static inline void *phys_to_virt(phys_addr_t x)
	{
	return (void *)__phys_to_virt(x);
	}

	/*
	* Drivers should NOT use these either.
	*/
	#define __pa(x) __virt_to_phys((unsigned long)(x))
	#define __va(x) ((void *)__phys_to_virt((phys_addr_t)(x)))
	#define pfn_to_kaddr(pfn) __va((phys_addr_t)(pfn) << PAGE_SHIFT)

	extern unsigned long (*arch_virt_to_idmap)(unsigned long x);

	/*
	* These are for systems that have a hardware interconnect supported alias of
	* physical memory for idmap purposes. Most cases should leave these
	* untouched. Note: this can only return addresses less than 4GiB.
	*/
	static inline unsigned long __virt_to_idmap(unsigned long x)
	{
	if (IS_ENABLED(CONFIG_MMU) && arch_virt_to_idmap)
	return arch_virt_to_idmap(x);
	else
	return __virt_to_phys(x);
	}

	#define virt_to_idmap(x) __virt_to_idmap((unsigned long)(x))

	/*
	* Virtual <-> DMA view memory address translations
	* Again, these are only valid on the kernel direct mapped RAM
	* memory. Use of these is deprecated (and that doesn't mean
	* use the __ prefixed forms instead.) See dma-mapping.h.
	*/
	#ifndef __virt_to_bus
	#define __virt_to_bus __virt_to_phys
	#define __bus_to_virt __phys_to_virt
	#define __pfn_to_bus(x) __pfn_to_phys(x)
	#define __bus_to_pfn(x) __phys_to_pfn(x)
	#endif

	/*
	* Conversion between a struct page and a physical address.
	*
	* page_to_pfn(page) convert a struct page * to a PFN number
	* pfn_to_page(pfn) convert a _valid_ PFN number to struct page *
	*
	* virt_to_page(k) convert a _valid_ virtual address to struct page *
	* virt_addr_valid(k) indicates whether a virtual address is valid
	*/
	#define ARCH_PFN_OFFSET PHYS_PFN_OFFSET

	#define virt_to_page(kaddr) pfn_to_page(virt_to_pfn(kaddr))
	#define virt_addr_valid(kaddr) (((unsigned long)(kaddr) >= PAGE_OFFSET && (unsigned long)(kaddr) < (unsigned long)high_memory) \
	&& pfn_valid(virt_to_pfn(kaddr)))

	#endif

	#include <asm-generic/memory_model.h>

	#endif