arm64: Use 42-bit address space with 64K pages

This patch expands the VA_BITS to 42 when the 64K page configuration is
enabled allowing 2TB kernel linear mapping. Linux still uses 2 levels of
page tables in this configuration with pgd now being a full page.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/Documentation/arm64/memory.txt b/Documentation/arm64/memory.txt
index f28899d..5e054bf 100644 (file)
--- a/Documentation/arm64/memory.txt
+++ b/Documentation/arm64/memory.txt
@@ -21,7 +21,7 @@ The swapper_pgd_dir address is written to TTBR1 and never written to
 TTBR0.
 
 
-AArch64 Linux memory layout:
+AArch64 Linux memory layout with 4KB pages:
 
 Start                  End                     Size            Use
 -----------------------------------------------------------------------
@@ -46,6 +46,31 @@ ffffffbffc000000     ffffffbfffffffff          64MB          modules
 ffffffc000000000       ffffffffffffffff         256GB          kernel logical memory map
 
 
+AArch64 Linux memory layout with 64KB pages:
+
+Start                  End                     Size            Use
+-----------------------------------------------------------------------
+0000000000000000       000003ffffffffff           4TB          user
+
+fffffc0000000000       fffffdfbfffeffff          ~2TB          vmalloc
+
+fffffdfbffff0000       fffffdfbffffffff          64KB          [guard page]
+
+fffffdfc00000000       fffffdfdffffffff           8GB          vmemmap
+
+fffffdfe00000000       fffffdfffbbfffff          ~8GB          [guard, future vmmemap]
+
+fffffdfffbc00000       fffffdfffbdfffff           2MB          earlyprintk device
+
+fffffdfffbe00000       fffffdfffbe0ffff          64KB          PCI I/O space
+
+fffffdfffbe10000       fffffdfffbffffff          ~2MB          [guard]
+
+fffffdfffc000000       fffffdffffffffff          64MB          modules
+
+fffffe0000000000       ffffffffffffffff           2TB          kernel logical memory map
+
+
 Translation table lookup with 4KB pages:
 
 +--------+--------+--------+--------+--------+--------+--------+--------+

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 20925bc..3776217 100644 (file)
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -33,18 +33,23 @@
 #define UL(x) _AC(x, UL)
 
 /*
- * PAGE_OFFSET - the virtual address of the start of the kernel image.
+ * PAGE_OFFSET - the virtual address of the start of the kernel image (top
+ *              (VA_BITS - 1))
  * 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)
+#ifdef CONFIG_ARM64_64K_PAGES
+#define VA_BITS                        (42)
+#else
+#define VA_BITS                        (39)
+#endif
+#define PAGE_OFFSET            (UL(0xffffffffffffffff) << (VA_BITS - 1))
 #define MODULES_END            (PAGE_OFFSET)
 #define MODULES_VADDR          (MODULES_END - SZ_64M)
 #define EARLYCON_IOBASE                (MODULES_VADDR - SZ_4M)
-#define VA_BITS                        (39)
 #define TASK_SIZE_64           (UL(1) << VA_BITS)
 
 #ifdef CONFIG_COMPAT

diff --git a/arch/arm64/include/asm/pgtable-2level-hwdef.h b/arch/arm64/include/asm/pgtable-2level-hwdef.h
index 0a8ed3f..2593b49 100644 (file)
--- a/arch/arm64/include/asm/pgtable-2level-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-2level-hwdef.h
@@ -21,10 +21,10 @@
  * 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.
+ * 4TB in the 64KB page configuration.
  */
 #define PTRS_PER_PTE           8192
-#define PTRS_PER_PGD           1024
+#define PTRS_PER_PGD           8192
 
 /*
  * PGDIR_SHIFT determines the size a top-level page table entry can map.

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index f0bebc5..17bd3af 100644 (file)
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -33,7 +33,7 @@
 /*
  * VMALLOC and SPARSEMEM_VMEMMAP ranges.
  */
-#define VMALLOC_START          UL(0xffffff8000000000)
+#define VMALLOC_START          (UL(0xffffffffffffffff) << VA_BITS)
 #define VMALLOC_END            (PAGE_OFFSET - UL(0x400000000) - SZ_64K)
 
 #define vmemmap                        ((struct page *)(VMALLOC_END + SZ_64K))