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: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Jungseok Lee <jungseoklee85@gmail.com>

diff --git a/Documentation/arm64/memory.txt b/Documentation/arm64/memory.txt
index 8845d08..344e85c 100644 (file)
--- a/Documentation/arm64/memory.txt
+++ b/Documentation/arm64/memory.txt
@@ -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.
 

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 8cdb7f3..f4615ba 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -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
 

diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index 2502754..7a3f462 100644 (file)
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -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>

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index a6db505..0bce493 100644 (file)
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -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