arch/arm64/include/asm/memory.h - linux - Git at Google

 /*
  * Based on arch/arm/include/asm/memory.h
  *
  * Copyright (C) 2000-2002 Russell King
  * Copyright (C) 2012 ARM Ltd.
  *
  * 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.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
  * Note: this file should not be included by non-asm/.h files
  */
 #ifndef __ASM_MEMORY_H
 #define __ASM_MEMORY_H

 #include <linux/compiler.h>
 #include <linux/const.h>
 #include <linux/types.h>
 #include <asm/bug.h>
 #include <asm/page-def.h>
 #include <asm/sizes.h>

 /*
  * Size of the PCI I/O space. This must remain a power of two so that
  * IO_SPACE_LIMIT acts as a mask for the low bits of I/O addresses.
  */
 #define PCI_IO_SIZE		SZ_16M

 /*
  * VMEMMAP_SIZE - allows the whole linear region to be covered by
  *                a struct page array
  */
 #define VMEMMAP_SIZE (UL(1) << (VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT))

 /*
  * PAGE_OFFSET - the virtual address of the start of the linear map (top
  *		 (VA_BITS - 1))
  * KIMAGE_VADDR - the virtual address of the start of the kernel image
  * VA_BITS - the maximum number of bits for virtual addresses.
  * VA_START - the first kernel virtual address.
  */
 #define VA_BITS			(CONFIG_ARM64_VA_BITS)
 #define VA_START		(UL(0xffffffffffffffff) - \
 	(UL(1) << VA_BITS) + 1)
 #define PAGE_OFFSET		(UL(0xffffffffffffffff) - \
 	(UL(1) << (VA_BITS - 1)) + 1)
 #define KIMAGE_VADDR		(MODULES_END)
 #define BPF_JIT_REGION_START	(VA_START + KASAN_SHADOW_SIZE)
 #define BPF_JIT_REGION_SIZE	(SZ_128M)
 #define BPF_JIT_REGION_END	(BPF_JIT_REGION_START + BPF_JIT_REGION_SIZE)
 #define MODULES_END		(MODULES_VADDR + MODULES_VSIZE)
 #define MODULES_VADDR		(BPF_JIT_REGION_END)
 #define MODULES_VSIZE		(SZ_128M)
 #define VMEMMAP_START		(PAGE_OFFSET - VMEMMAP_SIZE)
 #define PCI_IO_END		(VMEMMAP_START - SZ_2M)
 #define PCI_IO_START		(PCI_IO_END - PCI_IO_SIZE)
 #define FIXADDR_TOP		(PCI_IO_START - SZ_2M)

 #define KERNEL_START      _text
 #define KERNEL_END        _end

 #ifdef CONFIG_ARM64_USER_VA_BITS_52
 #define MAX_USER_VA_BITS	52
 #else
 #define MAX_USER_VA_BITS	VA_BITS
 #endif

 /*
  * KASAN requires 1/8th of the kernel virtual address space for the shadow
  * region. KASAN can bloat the stack significantly, so double the (minimum)
  * stack size when KASAN is in use, and then double it again if KASAN_EXTRA is
  * on.
  */
 #ifdef CONFIG_KASAN
 #define KASAN_SHADOW_SCALE_SHIFT 3
 #define KASAN_SHADOW_SIZE	(UL(1) << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT))
 #ifdef CONFIG_KASAN_EXTRA
 #define KASAN_THREAD_SHIFT	2
 #else
 #define KASAN_THREAD_SHIFT	1
 #endif /* CONFIG_KASAN_EXTRA */
 #else
 #define KASAN_SHADOW_SIZE	(0)
 #define KASAN_THREAD_SHIFT	0
 #endif

 #define MIN_THREAD_SHIFT	(14 + KASAN_THREAD_SHIFT)

 /*
  * VMAP'd stacks are allocated at page granularity, so we must ensure that such
  * stacks are a multiple of page size.
  */
 #if defined(CONFIG_VMAP_STACK) && (MIN_THREAD_SHIFT < PAGE_SHIFT)
 #define THREAD_SHIFT		PAGE_SHIFT
 #else
 #define THREAD_SHIFT		MIN_THREAD_SHIFT
 #endif

 #if THREAD_SHIFT >= PAGE_SHIFT
 #define THREAD_SIZE_ORDER	(THREAD_SHIFT - PAGE_SHIFT)
 #endif

 #define THREAD_SIZE		(UL(1) << THREAD_SHIFT)

 /*
  * By aligning VMAP'd stacks to 2 * THREAD_SIZE, we can detect overflow by
  * checking sp & (1 << THREAD_SHIFT), which we can do cheaply in the entry
  * assembly.
  */
 #ifdef CONFIG_VMAP_STACK
 #define THREAD_ALIGN		(2 * THREAD_SIZE)
 #else
 #define THREAD_ALIGN		THREAD_SIZE
 #endif

 #define IRQ_STACK_SIZE		THREAD_SIZE

 #define OVERFLOW_STACK_SIZE	SZ_4K

 /*
  * Alignment of kernel segments (e.g. .text, .data).
  */
 #if defined(CONFIG_DEBUG_ALIGN_RODATA)
 /*
  *  4 KB granule:   1 level 2 entry
  * 16 KB granule: 128 level 3 entries, with contiguous bit
  * 64 KB granule:  32 level 3 entries, with contiguous bit
  */
 #define SEGMENT_ALIGN			SZ_2M
 #else
 /*
  *  4 KB granule:  16 level 3 entries, with contiguous bit
  * 16 KB granule:   4 level 3 entries, without contiguous bit
  * 64 KB granule:   1 level 3 entry
  */
 #define SEGMENT_ALIGN			SZ_64K
 #endif

 /*
  * Memory types available.
  */
 #define MT_DEVICE_nGnRnE	0
 #define MT_DEVICE_nGnRE		1
 #define MT_DEVICE_GRE		2
 #define MT_NORMAL_NC		3
 #define MT_NORMAL		4
 #define MT_NORMAL_WT		5

 /*
  * Memory types for Stage-2 translation
  */
 #define MT_S2_NORMAL		0xf
 #define MT_S2_DEVICE_nGnRE	0x1

 /*
  * Memory types for Stage-2 translation when ID_AA64MMFR2_EL1.FWB is 0001
  * Stage-2 enforces Normal-WB and Device-nGnRE
  */
 #define MT_S2_FWB_NORMAL	6
 #define MT_S2_FWB_DEVICE_nGnRE	1

 #ifdef CONFIG_ARM64_4K_PAGES
 #define IOREMAP_MAX_ORDER	(PUD_SHIFT)
 #else
 #define IOREMAP_MAX_ORDER	(PMD_SHIFT)
 #endif

 #ifdef CONFIG_BLK_DEV_INITRD
 #define __early_init_dt_declare_initrd(__start, __end)			\
 	do {								\
 		initrd_start = (__start);				\
 		initrd_end = (__end);					\
 	} while (0)
 #endif

 #ifndef __ASSEMBLY__

 #include <linux/bitops.h>
 #include <linux/mmdebug.h>

 extern s64			memstart_addr;
 /* PHYS_OFFSET - the physical address of the start of memory. */
 #define PHYS_OFFSET		({ VM_BUG_ON(memstart_addr & 1); memstart_addr; })

 /* the virtual base of the kernel image (minus TEXT_OFFSET) */
 extern u64			kimage_vaddr;

 /* the offset between the kernel virtual and physical mappings */
 extern u64			kimage_voffset;

 static inline unsigned long kaslr_offset(void)
 {
 	return kimage_vaddr - KIMAGE_VADDR;
 }

 /* the actual size of a user virtual address */
 extern u64			vabits_user;

 /*
  * Allow all memory at the discovery stage. We will clip it later.
  */
 #define MIN_MEMBLOCK_ADDR	0
 #define MAX_MEMBLOCK_ADDR	U64_MAX

 /*
  * PFNs are used to describe any physical page; this means
  * PFN 0 == physical address 0.
  *
  * This is the PFN of the first RAM page in the kernel
  * direct-mapped view.  We assume this is the first page
  * of RAM in the mem_map as well.
  */
 #define PHYS_PFN_OFFSET	(PHYS_OFFSET >> PAGE_SHIFT)

 /*
  * 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.
  */


 /*
  * The linear kernel range starts in the middle of the virtual adddress
  * space. Testing the top bit for the start of the region is a
  * sufficient check.
  */
 #define __is_lm_address(addr)	(!!((addr) & BIT(VA_BITS - 1)))

 #define __lm_to_phys(addr)	(((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
 #define __kimg_to_phys(addr)	((addr) - kimage_voffset)

 #define __virt_to_phys_nodebug(x) ({					\
 	phys_addr_t __x = (phys_addr_t)(x);				\
 	__is_lm_address(__x) ? __lm_to_phys(__x) :			\
 			       __kimg_to_phys(__x);			\
 })

 #define __pa_symbol_nodebug(x)	__kimg_to_phys((phys_addr_t)(x))

 #ifdef CONFIG_DEBUG_VIRTUAL
 extern phys_addr_t __virt_to_phys(unsigned long x);
 extern phys_addr_t __phys_addr_symbol(unsigned long x);
 #else
 #define __virt_to_phys(x)	__virt_to_phys_nodebug(x)
 #define __phys_addr_symbol(x)	__pa_symbol_nodebug(x)
 #endif

 #define __phys_to_virt(x)	((unsigned long)((x) - PHYS_OFFSET) | PAGE_OFFSET)
 #define __phys_to_kimg(x)	((unsigned long)((x) + kimage_voffset))

 /*
  * 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)))

 /*
  * 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 __pa_symbol(x)		__phys_addr_symbol(RELOC_HIDE((unsigned long)(x), 0))
 #define __pa_nodebug(x)		__virt_to_phys_nodebug((unsigned long)(x))
 #define __va(x)			((void *)__phys_to_virt((phys_addr_t)(x)))
 #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
 #define virt_to_pfn(x)      __phys_to_pfn(__virt_to_phys((unsigned long)(x)))
 #define sym_to_pfn(x)	    __phys_to_pfn(__pa_symbol(x))

 /*
  *  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		((unsigned long)PHYS_PFN_OFFSET)

 #ifndef CONFIG_SPARSEMEM_VMEMMAP
 #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
 #define _virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
 #else
 #define __virt_to_pgoff(kaddr)	(((u64)(kaddr) & ~PAGE_OFFSET) / PAGE_SIZE * sizeof(struct page))
 #define __page_to_voff(kaddr)	(((u64)(kaddr) & ~VMEMMAP_START) * PAGE_SIZE / sizeof(struct page))

 #define page_to_virt(page)	((void *)((__page_to_voff(page)) | PAGE_OFFSET))
 #define virt_to_page(vaddr)	((struct page *)((__virt_to_pgoff(vaddr)) | VMEMMAP_START))

 #define _virt_addr_valid(kaddr)	pfn_valid((((u64)(kaddr) & ~PAGE_OFFSET) \
 					   + PHYS_OFFSET) >> PAGE_SHIFT)
 #endif
 #endif

 #define _virt_addr_is_linear(kaddr)	(((u64)(kaddr)) >= PAGE_OFFSET)
 #define virt_addr_valid(kaddr)		(_virt_addr_is_linear(kaddr) && \
 					 _virt_addr_valid(kaddr))

 #include <asm-generic/memory_model.h>

 #endif
	/*
	* Based on arch/arm/include/asm/memory.h
	*
	* Copyright (C) 2000-2002 Russell King
	* Copyright (C) 2012 ARM Ltd.
	*
	* 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.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	*
	* Note: this file should not be included by non-asm/.h files
	*/
	#ifndef __ASM_MEMORY_H
	#define __ASM_MEMORY_H

	#include <linux/compiler.h>
	#include <linux/const.h>
	#include <linux/types.h>
	#include <asm/bug.h>
	#include <asm/page-def.h>
	#include <asm/sizes.h>

	/*
	* Size of the PCI I/O space. This must remain a power of two so that
	* IO_SPACE_LIMIT acts as a mask for the low bits of I/O addresses.
	*/
	#define PCI_IO_SIZE SZ_16M

	/*
	* VMEMMAP_SIZE - allows the whole linear region to be covered by
	* a struct page array
	*/
	#define VMEMMAP_SIZE (UL(1) << (VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT))

	/*
	* PAGE_OFFSET - the virtual address of the start of the linear map (top
	* (VA_BITS - 1))
	* KIMAGE_VADDR - the virtual address of the start of the kernel image
	* VA_BITS - the maximum number of bits for virtual addresses.
	* VA_START - the first kernel virtual address.
	*/
	#define VA_BITS (CONFIG_ARM64_VA_BITS)
	#define VA_START (UL(0xffffffffffffffff) - \
	(UL(1) << VA_BITS) + 1)
	#define PAGE_OFFSET (UL(0xffffffffffffffff) - \
	(UL(1) << (VA_BITS - 1)) + 1)
	#define KIMAGE_VADDR (MODULES_END)
	#define BPF_JIT_REGION_START (VA_START + KASAN_SHADOW_SIZE)
	#define BPF_JIT_REGION_SIZE (SZ_128M)
	#define BPF_JIT_REGION_END (BPF_JIT_REGION_START + BPF_JIT_REGION_SIZE)
	#define MODULES_END (MODULES_VADDR + MODULES_VSIZE)
	#define MODULES_VADDR (BPF_JIT_REGION_END)
	#define MODULES_VSIZE (SZ_128M)
	#define VMEMMAP_START (PAGE_OFFSET - VMEMMAP_SIZE)
	#define PCI_IO_END (VMEMMAP_START - SZ_2M)
	#define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE)
	#define FIXADDR_TOP (PCI_IO_START - SZ_2M)

	#define KERNEL_START _text
	#define KERNEL_END _end

	#ifdef CONFIG_ARM64_USER_VA_BITS_52
	#define MAX_USER_VA_BITS 52
	#else
	#define MAX_USER_VA_BITS VA_BITS
	#endif

	/*
	* KASAN requires 1/8th of the kernel virtual address space for the shadow
	* region. KASAN can bloat the stack significantly, so double the (minimum)
	* stack size when KASAN is in use, and then double it again if KASAN_EXTRA is
	* on.
	*/
	#ifdef CONFIG_KASAN
	#define KASAN_SHADOW_SCALE_SHIFT 3
	#define KASAN_SHADOW_SIZE (UL(1) << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT))
	#ifdef CONFIG_KASAN_EXTRA
	#define KASAN_THREAD_SHIFT 2
	#else
	#define KASAN_THREAD_SHIFT 1
	#endif /* CONFIG_KASAN_EXTRA */
	#else
	#define KASAN_SHADOW_SIZE (0)
	#define KASAN_THREAD_SHIFT 0
	#endif

	#define MIN_THREAD_SHIFT (14 + KASAN_THREAD_SHIFT)

	/*
	* VMAP'd stacks are allocated at page granularity, so we must ensure that such
	* stacks are a multiple of page size.
	*/
	#if defined(CONFIG_VMAP_STACK) && (MIN_THREAD_SHIFT < PAGE_SHIFT)
	#define THREAD_SHIFT PAGE_SHIFT
	#else
	#define THREAD_SHIFT MIN_THREAD_SHIFT
	#endif

	#if THREAD_SHIFT >= PAGE_SHIFT
	#define THREAD_SIZE_ORDER (THREAD_SHIFT - PAGE_SHIFT)
	#endif

	#define THREAD_SIZE (UL(1) << THREAD_SHIFT)

	/*
	* By aligning VMAP'd stacks to 2 * THREAD_SIZE, we can detect overflow by
	* checking sp & (1 << THREAD_SHIFT), which we can do cheaply in the entry
	* assembly.
	*/
	#ifdef CONFIG_VMAP_STACK
	#define THREAD_ALIGN (2 * THREAD_SIZE)
	#else
	#define THREAD_ALIGN THREAD_SIZE
	#endif

	#define IRQ_STACK_SIZE THREAD_SIZE

	#define OVERFLOW_STACK_SIZE SZ_4K

	/*
	* Alignment of kernel segments (e.g. .text, .data).
	*/
	#if defined(CONFIG_DEBUG_ALIGN_RODATA)
	/*
	* 4 KB granule: 1 level 2 entry
	* 16 KB granule: 128 level 3 entries, with contiguous bit
	* 64 KB granule: 32 level 3 entries, with contiguous bit
	*/
	#define SEGMENT_ALIGN SZ_2M
	#else
	/*
	* 4 KB granule: 16 level 3 entries, with contiguous bit
	* 16 KB granule: 4 level 3 entries, without contiguous bit
	* 64 KB granule: 1 level 3 entry
	*/
	#define SEGMENT_ALIGN SZ_64K
	#endif

	/*
	* Memory types available.
	*/
	#define MT_DEVICE_nGnRnE 0
	#define MT_DEVICE_nGnRE 1
	#define MT_DEVICE_GRE 2
	#define MT_NORMAL_NC 3
	#define MT_NORMAL 4
	#define MT_NORMAL_WT 5

	/*
	* Memory types for Stage-2 translation
	*/
	#define MT_S2_NORMAL 0xf
	#define MT_S2_DEVICE_nGnRE 0x1

	/*
	* Memory types for Stage-2 translation when ID_AA64MMFR2_EL1.FWB is 0001
	* Stage-2 enforces Normal-WB and Device-nGnRE
	*/
	#define MT_S2_FWB_NORMAL 6
	#define MT_S2_FWB_DEVICE_nGnRE 1

	#ifdef CONFIG_ARM64_4K_PAGES
	#define IOREMAP_MAX_ORDER (PUD_SHIFT)
	#else
	#define IOREMAP_MAX_ORDER (PMD_SHIFT)
	#endif

	#ifdef CONFIG_BLK_DEV_INITRD
	#define __early_init_dt_declare_initrd(__start, __end) \
	do { \
	initrd_start = (__start); \
	initrd_end = (__end); \
	} while (0)
	#endif

	#ifndef __ASSEMBLY__

	#include <linux/bitops.h>
	#include <linux/mmdebug.h>

	extern s64 memstart_addr;
	/* PHYS_OFFSET - the physical address of the start of memory. */
	#define PHYS_OFFSET ({ VM_BUG_ON(memstart_addr & 1); memstart_addr; })

	/* the virtual base of the kernel image (minus TEXT_OFFSET) */
	extern u64 kimage_vaddr;

	/* the offset between the kernel virtual and physical mappings */
	extern u64 kimage_voffset;

	static inline unsigned long kaslr_offset(void)
	{
	return kimage_vaddr - KIMAGE_VADDR;
	}

	/* the actual size of a user virtual address */
	extern u64 vabits_user;

	/*
	* Allow all memory at the discovery stage. We will clip it later.
	*/
	#define MIN_MEMBLOCK_ADDR 0
	#define MAX_MEMBLOCK_ADDR U64_MAX

	/*
	* PFNs are used to describe any physical page; this means
	* PFN 0 == physical address 0.
	*
	* This is the PFN of the first RAM page in the kernel
	* direct-mapped view. We assume this is the first page
	* of RAM in the mem_map as well.
	*/
	#define PHYS_PFN_OFFSET (PHYS_OFFSET >> PAGE_SHIFT)

	/*
	* 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.
	*/


	/*
	* The linear kernel range starts in the middle of the virtual adddress
	* space. Testing the top bit for the start of the region is a
	* sufficient check.
	*/
	#define __is_lm_address(addr) (!!((addr) & BIT(VA_BITS - 1)))

	#define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
	#define __kimg_to_phys(addr) ((addr) - kimage_voffset)

	#define __virt_to_phys_nodebug(x) ({ \
	phys_addr_t __x = (phys_addr_t)(x); \
	__is_lm_address(__x) ? __lm_to_phys(__x) : \
	__kimg_to_phys(__x); \
	})

	#define __pa_symbol_nodebug(x) __kimg_to_phys((phys_addr_t)(x))

	#ifdef CONFIG_DEBUG_VIRTUAL
	extern phys_addr_t __virt_to_phys(unsigned long x);
	extern phys_addr_t __phys_addr_symbol(unsigned long x);
	#else
	#define __virt_to_phys(x) __virt_to_phys_nodebug(x)
	#define __phys_addr_symbol(x) __pa_symbol_nodebug(x)
	#endif

	#define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET) \| PAGE_OFFSET)
	#define __phys_to_kimg(x) ((unsigned long)((x) + kimage_voffset))

	/*
	* 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)))

	/*
	* 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 __pa_symbol(x) __phys_addr_symbol(RELOC_HIDE((unsigned long)(x), 0))
	#define __pa_nodebug(x) __virt_to_phys_nodebug((unsigned long)(x))
	#define __va(x) ((void *)__phys_to_virt((phys_addr_t)(x)))
	#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
	#define virt_to_pfn(x) __phys_to_pfn(__virt_to_phys((unsigned long)(x)))
	#define sym_to_pfn(x) __phys_to_pfn(__pa_symbol(x))

	/*
	* 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 ((unsigned long)PHYS_PFN_OFFSET)

	#ifndef CONFIG_SPARSEMEM_VMEMMAP
	#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
	#define _virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
	#else
	#define __virt_to_pgoff(kaddr) (((u64)(kaddr) & ~PAGE_OFFSET) / PAGE_SIZE * sizeof(struct page))
	#define __page_to_voff(kaddr) (((u64)(kaddr) & ~VMEMMAP_START) * PAGE_SIZE / sizeof(struct page))

	#define page_to_virt(page) ((void *)((__page_to_voff(page)) \| PAGE_OFFSET))
	#define virt_to_page(vaddr) ((struct page *)((__virt_to_pgoff(vaddr)) \| VMEMMAP_START))

	#define _virt_addr_valid(kaddr) pfn_valid((((u64)(kaddr) & ~PAGE_OFFSET) \
	+ PHYS_OFFSET) >> PAGE_SHIFT)
	#endif
	#endif

	#define _virt_addr_is_linear(kaddr) (((u64)(kaddr)) >= PAGE_OFFSET)
	#define virt_addr_valid(kaddr) (_virt_addr_is_linear(kaddr) && \
	_virt_addr_valid(kaddr))

	#include <asm-generic/memory_model.h>

	#endif