arm64: MMU definitions

		     Memory Layout on AArch64 Linux

		     ==============================

Author: Catalin Marinas <catalin.marinas@arm.com>

Date  : 20 February 2012

This document describes the virtual memory layout used by the AArch64

Linux kernel. The architecture allows up to 4 levels of translation

tables with a 4KB page size and up to 3 levels with a 64KB page size.

AArch64 Linux uses 3 levels of translation tables with the 4KB page

configuration, allowing 39-bit (512GB) virtual addresses for both user

and kernel. With 64KB pages, only 2 levels of translation tables are

used but the memory layout is the same.

User addresses have bits 63:39 set to 0 while the kernel addresses have

the same bits set to 1. TTBRx selection is given by bit 63 of the

virtual address. The swapper_pg_dir contains only kernel (global)

mappings while the user pgd contains only user (non-global) mappings.

The swapper_pgd_dir address is written to TTBR1 and never written to

TTBR0.

AArch64 Linux memory layout:

Start			End			Size		Use

-----------------------------------------------------------------------

0000000000000000	0000007fffffffff	 512GB		user

ffffff8000000000	ffffffbbfffcffff	~240GB		vmalloc

ffffffbbfffd0000	ffffffbcfffdffff	  64KB		[guard page]

ffffffbbfffe0000	ffffffbcfffeffff	  64KB		PCI I/O space

ffffffbbffff0000	ffffffbcffffffff	  64KB		[guard page]

ffffffbc00000000	ffffffbdffffffff	   8GB		vmemmap

ffffffbe00000000	ffffffbffbffffff	  ~8GB		[guard, future vmmemap]

ffffffbffc000000	ffffffbfffffffff	  64MB		modules

ffffffc000000000	ffffffffffffffff	 256GB		memory

Translation table lookup with 4KB pages:

+--------+--------+--------+--------+--------+--------+--------+--------+

|63    56|55    48|47    40|39    32|31    24|23    16|15     8|7      0|

+--------+--------+--------+--------+--------+--------+--------+--------+

 |                 |         |         |         |         |

 |                 |         |         |         |         v

 |                 |         |         |         |   [11:0]  in-page offset

 |                 |         |         |         +-> [20:12] L3 index

 |                 |         |         +-----------> [29:21] L2 index

 |                 |         +---------------------> [38:30] L1 index

 |                 +-------------------------------> [47:39] L0 index (not used)

 +-------------------------------------------------> [63] TTBR0/1

Translation table lookup with 64KB pages:

+--------+--------+--------+--------+--------+--------+--------+--------+

|63    56|55    48|47    40|39    32|31    24|23    16|15     8|7      0|

+--------+--------+--------+--------+--------+--------+--------+--------+

 |                 |    |               |              |

 |                 |    |               |              v

 |                 |    |               |            [15:0]  in-page offset

 |                 |    |               +----------> [28:16] L3 index

 |                 |    +--------------------------> [41:29] L2 index (only 38:29 used)

 |                 +-------------------------------> [47:42] L1 index (not used)

 +-------------------------------------------------> [63] TTBR0/1

/*

 * 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/sizes.h>

/*

 * 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.

 * VA_BITS - the maximum number of bits for virtual addresses.

 * TASK_SIZE - the maximum size of a user space task.

 * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.

 * The module space lives between the addresses given by TASK_SIZE

 * and PAGE_OFFSET - it must be within 128MB of the kernel text.

 */

#define PAGE_OFFSET		UL(0xffffffc000000000)

#define MODULES_END		(PAGE_OFFSET)

#define MODULES_VADDR		(MODULES_END - SZ_64M)

#define VA_BITS			(39)

#define TASK_SIZE_64		(UL(1) << VA_BITS)

#ifdef CONFIG_COMPAT

#define TASK_SIZE_32		UL(0x100000000)

#define TASK_SIZE		(test_thread_flag(TIF_32BIT) ? \

				TASK_SIZE_32 : TASK_SIZE_64)

#else

#define TASK_SIZE		TASK_SIZE_64

#endif /* CONFIG_COMPAT */

#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 4))

#if TASK_SIZE_64 > MODULES_VADDR

#error Top of 64-bit user space clashes with start of module space

#endif

/*

 * 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.

 */

#define __virt_to_phys(x)	(((phys_addr_t)(x) - PAGE_OFFSET + PHYS_OFFSET))

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

/*

 * Convert a physical address to a Page Frame Number and back

 */

#define	__phys_to_pfn(paddr)	((unsigned long)((paddr) >> PAGE_SHIFT))

#define	__pfn_to_phys(pfn)	((phys_addr_t)(pfn) << PAGE_SHIFT)

/*

 * 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)))

/*

 * 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

#ifndef __ASSEMBLY__

extern phys_addr_t		memstart_addr;

/* PHYS_OFFSET - the physical address of the start of memory. */

#define PHYS_OFFSET		({ memstart_addr; })

/*

 * 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)

/*

 * Note: Drivers should NOT use these.  They are the wrong

 * translation for translating DMA addresses.  Use the driver

 * DMA support - see dma-mapping.h.

 */

static inline phys_addr_t virt_to_phys(const volatile void *x)

{

	return __virt_to_phys((unsigned long)(x));

}

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((pfn) << PAGE_SHIFT)

/*

 *  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(__pa(kaddr) >> PAGE_SHIFT)

#define	virt_addr_valid(kaddr)	(((void *)(kaddr) >= (void *)PAGE_OFFSET) && \

				 ((void *)(kaddr) < (void *)high_memory))

#endif

#include <asm-generic/memory_model.h>

#endif

/*

 * 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/>.

 */

#ifndef __ASM_MMU_H

#define __ASM_MMU_H

typedef struct {

	unsigned int id;

	raw_spinlock_t id_lock;

	void *vdso;

} mm_context_t;

#define ASID(mm)	((mm)->context.id & 0xffff)

extern void paging_init(void);

extern void setup_mm_for_reboot(void);

#endif

/*

 * 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/>.

 */

#ifndef __ASM_PGTABLE_2LEVEL_HWDEF_H

#define __ASM_PGTABLE_2LEVEL_HWDEF_H

/*

 * With LPAE and 64KB pages, there are 2 levels of page tables. Each level has

 * 8192 entries of 8 bytes each, occupying a 64KB page. Levels 0 and 1 are not

 * used. The 2nd level table (PGD for Linux) can cover a range of 4TB, each

 * entry representing 512MB. The user and kernel address spaces are limited to

 * 512GB and therefore we only use 1024 entries in the PGD.

 */

#define PTRS_PER_PTE		8192

#define PTRS_PER_PGD		1024

/*

 * PGDIR_SHIFT determines the size a top-level page table entry can map.

 */

#define PGDIR_SHIFT		29

#define PGDIR_SIZE		(_AC(1, UL) << PGDIR_SHIFT)

#define PGDIR_MASK		(~(PGDIR_SIZE-1))

/*

 * section address mask and size definitions.

 */

#define SECTION_SHIFT		29

#define SECTION_SIZE		(_AC(1, UL) << SECTION_SHIFT)

#define SECTION_MASK		(~(SECTION_SIZE-1))

#endif

/*

 * 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/>.

 */

#ifndef __ASM_PGTABLE_2LEVEL_TYPES_H

#define __ASM_PGTABLE_2LEVEL_TYPES_H

typedef u64 pteval_t;

typedef u64 pgdval_t;

typedef pgdval_t pmdval_t;

#undef STRICT_MM_TYPECHECKS

#ifdef STRICT_MM_TYPECHECKS

/*

 * These are used to make use of C type-checking..

 */

typedef struct { pteval_t pte; } pte_t;

typedef struct { pgdval_t pgd; } pgd_t;

typedef struct { pteval_t pgprot; } pgprot_t;

#define pte_val(x)      ((x).pte)

#define pgd_val(x)	((x).pgd)

#define pgprot_val(x)   ((x).pgprot)

#define __pte(x)        ((pte_t) { (x) } )

#define __pgd(x)	((pgd_t) { (x) } )

#define __pgprot(x)     ((pgprot_t) { (x) } )

#else	/* !STRICT_MM_TYPECHECKS */

typedef pteval_t pte_t;

typedef pgdval_t pgd_t;

typedef pteval_t pgprot_t;

#define pte_val(x)	(x)

#define pgd_val(x)	(x)

#define pgprot_val(x)	(x)

#define __pte(x)	(x)

#define __pgd(x)	(x)

#define __pgprot(x)	(x)

#endif	/* STRICT_MM_TYPECHECKS */

#include <asm-generic/pgtable-nopmd.h>

#endif	/* __ASM_PGTABLE_2LEVEL_TYPES_H */