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Commit 383c2799 authored by Catalin Marinas's avatar Catalin Marinas
Browse files

arm64: Add support for 48-bit VA space with 64KB page configuration 



This patch allows support for 3 levels of page tables with 64KB page
configuration allowing 48-bit VA space. The pgd is no longer a full
PAGE_SIZE (PTRS_PER_PGD is 64) and (swapper|idmap)_pg_dir are not fully
populated (pgd_alloc falls back to kzalloc).

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Tested-by: default avatarJungseok Lee <jungseoklee85@gmail.com>
parent 7078db46

Documentation/arm64/memory.txt

+8 −0
Original line number Diff line number Diff line
@@ -45,6 +45,14 @@ Start End Size Use 
fffffc0000000000	ffffffffffffffff	   4TB		kernel





AArch64 Linux memory layout with 64KB pages + 3 levels:



Start			End			Size		Use

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

0000000000000000	0000ffffffffffff	 256TB		user

ffff000000000000	ffffffffffffffff	 256TB		kernel





For details of the virtual kernel memory layout please see the kernel

booting log.

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -210,6 +210,7 @@ config ARM64_VA_BITS 
config ARM64_PGTABLE_LEVELS

	int

	default 2 if ARM64_64K_PAGES && ARM64_VA_BITS_42

	default 3 if ARM64_64K_PAGES && ARM64_VA_BITS_48

	default 3 if ARM64_4K_PAGES && ARM64_VA_BITS_39

	default 4 if ARM64_4K_PAGES && ARM64_VA_BITS_48

arch/arm64/include/asm/page.h

+9 −7
Original line number Diff line number Diff line
@@ -34,17 +34,19 @@ 
/*

 * The idmap and swapper page tables need some space reserved in the kernel

 * image. Both require pgd, pud (4 levels only) and pmd tables to (section)

 * map the kernel. The swapper also maps the FDT (see __create_page_tables for

 * more information).

 * map the kernel. With the 64K page configuration, swapper and idmap need to

 * map to pte level. The swapper also maps the FDT (see __create_page_tables

 * for more information).

 */

#if CONFIG_ARM64_PGTABLE_LEVELS == 4

#define SWAPPER_DIR_SIZE	(3 * PAGE_SIZE)

#define IDMAP_DIR_SIZE		(3 * PAGE_SIZE)

#ifdef CONFIG_ARM64_64K_PAGES

#define SWAPPER_PGTABLE_LEVELS	(CONFIG_ARM64_PGTABLE_LEVELS)

#else

#define SWAPPER_DIR_SIZE	(2 * PAGE_SIZE)

#define IDMAP_DIR_SIZE		(2 * PAGE_SIZE)

#define SWAPPER_PGTABLE_LEVELS	(CONFIG_ARM64_PGTABLE_LEVELS - 1)

#endif



#define SWAPPER_DIR_SIZE	(SWAPPER_PGTABLE_LEVELS * PAGE_SIZE)

#define IDMAP_DIR_SIZE		(SWAPPER_DIR_SIZE)



#ifndef __ASSEMBLY__



#include <asm/pgtable-types.h>

arch/arm64/kernel/head.S

+4 −2
Original line number Diff line number Diff line
@@ -55,9 +55,11 @@ 
#ifdef CONFIG_ARM64_64K_PAGES

#define BLOCK_SHIFT	PAGE_SHIFT

#define BLOCK_SIZE	PAGE_SIZE

#define TABLE_SHIFT	PMD_SHIFT

#else

#define BLOCK_SHIFT	SECTION_SHIFT

#define BLOCK_SIZE	SECTION_SIZE

#define TABLE_SHIFT	PUD_SHIFT

#endif



#define KERNEL_START	KERNEL_RAM_VADDR
@@ -505,8 +507,8 @@ ENDPROC(__calc_phys_offset) 
 */

	.macro	create_pgd_entry, tbl, virt, tmp1, tmp2

	create_table_entry \tbl, \virt, PGDIR_SHIFT, PTRS_PER_PGD, \tmp1, \tmp2

#if CONFIG_ARM64_PGTABLE_LEVELS == 4

	create_table_entry \tbl, \virt, PUD_SHIFT, PTRS_PER_PUD, \tmp1, \tmp2

#if SWAPPER_PGTABLE_LEVELS == 3

	create_table_entry \tbl, \virt, TABLE_SHIFT, PTRS_PER_PTE, \tmp1, \tmp2

#endif

	.endm