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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>
This commit is contained in:
Catalin Marinas 2013-10-23 16:50:07 +01:00
parent 122e2fa0d3
commit 847264fb7e
4 changed files with 37 additions and 7 deletions
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27
Documentation/arm64/memory.txt
View File

@ -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:
+--------+--------+--------+--------+--------+--------+--------+--------+

11
arch/arm64/include/asm/memory.h
View File

@ -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

4
arch/arm64/include/asm/pgtable-2level-hwdef.h
View File

@ -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.

2
arch/arm64/include/asm/pgtable.h
View File

@ -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))