arm64: MMU definitions

The virtual memory layout is described in
Documentation/arm64/memory.txt. This patch adds the MMU definitions for
the 4KB and 64KB translation table configurations. The SECTION_SIZE is
2MB with 4KB page and 512MB with 64KB page configuration.

PHYS_OFFSET is calculated at run-time and stored in a variable (no
run-time code patching at this stage).

On the current implementation, both user and kernel address spaces are
512G (39-bit) each with a maximum of 256G for the RAM linear mapping.
Linux uses 3 levels of translation tables with the 4K page configuration
and 2 levels with the 64K configuration. Extending the memory space
beyond 39-bit with the 4K pages or 42-bit with 64K pages requires an
additional level of translation tables.

The SPARSEMEM configuration is global to all AArch64 platforms and
allows for 1GB sections with SPARSEMEM_VMEMMAP enabled by default.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

Documentation/arm64/memory.txt

@@ -0,0 +1,73 @@
+		     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

arch/arm64/include/asm/memory.h

@@ -0,0 +1,144 @@
+/*
+ * 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

arch/arm64/include/asm/mmu.h

@@ -0,0 +1,30 @@
+/*
+ * 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

arch/arm64/include/asm/pgtable-2level-hwdef.h

@@ -0,0 +1,43 @@
+/*
+ * 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

arch/arm64/include/asm/pgtable-2level-types.h

@@ -0,0 +1,60 @@
+/*
+ * 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 */