Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4c7c4483 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Ingo Molnar
Browse files

x86/mm: Define virtual memory map for 5-level paging 



The first part of memory map (up to %esp fixup) simply scales existing
map for 4-level paging by factor of 9 -- number of bits addressed by
the additional page table level.

The rest of the map is unchanged.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170330080731.65421-4-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 361b4b58

Documentation/x86/x86_64/mm.txt

+30 −3
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ 
Virtual memory map with 4 level page tables:



0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm

hole caused by [48:63] sign extension

hole caused by [47:63] sign extension

ffff800000000000 - ffff87ffffffffff (=43 bits) guard hole, reserved for hypervisor

ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory

ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole
@@ -23,12 +23,39 @@ ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space (variable) 
ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls

ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole



Virtual memory map with 5 level page tables:



0000000000000000 - 00ffffffffffffff (=56 bits) user space, different per mm

hole caused by [56:63] sign extension

ff00000000000000 - ff0fffffffffffff (=52 bits) guard hole, reserved for hypervisor

ff10000000000000 - ff8fffffffffffff (=55 bits) direct mapping of all phys. memory

ff90000000000000 - ff91ffffffffffff (=49 bits) hole

ff92000000000000 - ffd1ffffffffffff (=54 bits) vmalloc/ioremap space

ffd2000000000000 - ffd3ffffffffffff (=49 bits) hole

ffd4000000000000 - ffd5ffffffffffff (=49 bits) virtual memory map (512TB)

... unused hole ...

ffd8000000000000 - fff7ffffffffffff (=53 bits) kasan shadow memory (8PB)

... unused hole ...

ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks

... unused hole ...

ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space

... unused hole ...

ffffffff80000000 - ffffffff9fffffff (=512 MB)  kernel text mapping, from phys 0

ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space

ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls

ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole



Architecture defines a 64-bit virtual address. Implementations can support

less. Currently supported are 48- and 57-bit virtual addresses. Bits 63

through to the most-significant implemented bit are set to either all ones

or all zero. This causes hole between user space and kernel addresses.



The direct mapping covers all memory in the system up to the highest

memory address (this means in some cases it can also include PCI memory

holes).



vmalloc space is lazily synchronized into the different PML4 pages of

the processes using the page fault handler, with init_level4_pgt as

vmalloc space is lazily synchronized into the different PML4/PML5 pages of

the processes using the page fault handler, with init_top_pgt as

reference.



Current X86-64 implementations support up to 46 bits of address space (64 TB),

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -291,6 +291,7 @@ config ARCH_SUPPORTS_DEBUG_PAGEALLOC 
config KASAN_SHADOW_OFFSET

	hex

	depends on KASAN

	default 0xdff8000000000000 if X86_5LEVEL

	default 0xdffffc0000000000



config HAVE_INTEL_TXT

arch/x86/include/asm/kasan.h

+6 −3
Original line number Diff line number Diff line
@@ -11,9 +11,12 @@ 
 * 'kernel address space start' >> KASAN_SHADOW_SCALE_SHIFT

 */

#define KASAN_SHADOW_START      (KASAN_SHADOW_OFFSET + \

					(0xffff800000000000ULL >> 3))

/* 47 bits for kernel address -> (47 - 3) bits for shadow */

#define KASAN_SHADOW_END        (KASAN_SHADOW_START + (1ULL << (47 - 3)))

					((-1UL << __VIRTUAL_MASK_SHIFT) >> 3))

/*

 * 47 bits for kernel address -> (47 - 3) bits for shadow

 * 56 bits for kernel address -> (56 - 3) bits for shadow

 */

#define KASAN_SHADOW_END        (KASAN_SHADOW_START + (1ULL << (__VIRTUAL_MASK_SHIFT - 3)))



#ifndef __ASSEMBLY__

arch/x86/include/asm/page_64_types.h

+10 −0
Original line number Diff line number Diff line
@@ -36,7 +36,12 @@ 
 * hypervisor to fit.  Choosing 16 slots here is arbitrary, but it's

 * what Xen requires.

 */

#ifdef CONFIG_X86_5LEVEL

#define __PAGE_OFFSET_BASE      _AC(0xff10000000000000, UL)

#else

#define __PAGE_OFFSET_BASE      _AC(0xffff880000000000, UL)

#endif



#ifdef CONFIG_RANDOMIZE_MEMORY

#define __PAGE_OFFSET           page_offset_base

#else
@@ -46,8 +51,13 @@ 
#define __START_KERNEL_map	_AC(0xffffffff80000000, UL)



/* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */

#ifdef CONFIG_X86_5LEVEL

#define __PHYSICAL_MASK_SHIFT	52

#define __VIRTUAL_MASK_SHIFT	56

#else

#define __PHYSICAL_MASK_SHIFT	46

#define __VIRTUAL_MASK_SHIFT	47

#endif



/*

 * Kernel image size is limited to 1GiB due to the fixmap living in the

arch/x86/include/asm/pgtable_64_types.h

+6 −0
Original line number Diff line number Diff line
@@ -56,9 +56,15 @@ typedef struct { pteval_t pte; } pte_t; 


/* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */

#define MAXMEM		_AC(__AC(1, UL) << MAX_PHYSMEM_BITS, UL)

#ifdef CONFIG_X86_5LEVEL

#define VMALLOC_SIZE_TB _AC(16384, UL)

#define __VMALLOC_BASE	_AC(0xff92000000000000, UL)

#define __VMEMMAP_BASE	_AC(0xffd4000000000000, UL)

#else

#define VMALLOC_SIZE_TB	_AC(32, UL)

#define __VMALLOC_BASE	_AC(0xffffc90000000000, UL)

#define __VMEMMAP_BASE	_AC(0xffffea0000000000, UL)

#endif

#ifdef CONFIG_RANDOMIZE_MEMORY

#define VMALLOC_START	vmalloc_base

#define VMEMMAP_START	vmemmap_base