Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | |
| 2 | <previous description obsolete, deleted> |
| 3 | |
| 4 | Virtual memory map with 4 level page tables: |
| 5 | |
Randy Dunlap | 57d3077 | 2007-02-13 13:26:23 +0100 | [diff] [blame] | 6 | 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | hole caused by [48:63] sign extension |
Dave Hansen | beb9147 | 2014-09-18 12:56:06 -0700 | [diff] [blame] | 8 | ffff800000000000 - ffff87ffffffffff (=43 bits) guard hole, reserved for hypervisor |
H. Peter Anvin | 2feceef | 2009-05-05 19:07:07 -0700 | [diff] [blame] | 9 | ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory |
Rik van Riel | c898faf | 2009-05-05 17:28:56 -0400 | [diff] [blame] | 10 | ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole |
| 11 | ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space |
| 12 | ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole |
| 13 | ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | ... unused hole ... |
Lorenzo Stoakes | 9d9cce7 | 2016-08-23 09:00:45 +0100 | [diff] [blame] | 15 | ffffec0000000000 - fffffbffffffffff (=44 bits) kasan shadow memory (16TB) |
Andrey Ryabinin | ef7f0d6 | 2015-02-13 14:39:25 -0800 | [diff] [blame] | 16 | ... unused hole ... |
H. Peter Anvin | 3891a04 | 2014-04-29 16:46:09 -0700 | [diff] [blame] | 17 | ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks |
| 18 | ... unused hole ... |
Lorenzo Stoakes | 9d9cce7 | 2016-08-23 09:00:45 +0100 | [diff] [blame] | 19 | ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space |
Matt Fleming | ff3d0a1 | 2015-11-27 21:09:35 +0000 | [diff] [blame] | 20 | ... unused hole ... |
Lorenzo Stoakes | 9d9cce7 | 2016-08-23 09:00:45 +0100 | [diff] [blame] | 21 | ffffffff80000000 - ffffffff9fffffff (=512 MB) kernel text mapping, from phys 0 |
Juergen Gross | 78b0634 | 2016-04-22 09:35:04 +0200 | [diff] [blame] | 22 | ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space |
Borislav Petkov | aca91bf | 2013-03-04 21:16:18 +0100 | [diff] [blame] | 23 | ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls |
| 24 | ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | |
Randy Dunlap | 57d3077 | 2007-02-13 13:26:23 +0100 | [diff] [blame] | 26 | The direct mapping covers all memory in the system up to the highest |
Andi Kleen | 8315eca | 2005-11-05 17:25:54 +0100 | [diff] [blame] | 27 | memory address (this means in some cases it can also include PCI memory |
Randy Dunlap | 57d3077 | 2007-02-13 13:26:23 +0100 | [diff] [blame] | 28 | holes). |
Andi Kleen | 8315eca | 2005-11-05 17:25:54 +0100 | [diff] [blame] | 29 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | vmalloc space is lazily synchronized into the different PML4 pages of |
| 31 | the processes using the page fault handler, with init_level4_pgt as |
| 32 | reference. |
| 33 | |
Juergen Gross | 78b0634 | 2016-04-22 09:35:04 +0200 | [diff] [blame] | 34 | Current X86-64 implementations support up to 46 bits of address space (64 TB), |
| 35 | which is our current limit. This expands into MBZ space in the page tables. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 36 | |
Matt Fleming | ff3d0a1 | 2015-11-27 21:09:35 +0000 | [diff] [blame] | 37 | We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual |
| 38 | memory window (this size is arbitrary, it can be raised later if needed). |
| 39 | The mappings are not part of any other kernel PGD and are only available |
| 40 | during EFI runtime calls. |
Borislav Petkov | d2f7cbe | 2013-10-31 17:25:08 +0100 | [diff] [blame] | 41 | |
Thomas Garnier | 0483e1f | 2016-06-21 17:47:02 -0700 | [diff] [blame] | 42 | Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all |
| 43 | physical memory, vmalloc/ioremap space and virtual memory map are randomized. |
| 44 | Their order is preserved but their base will be offset early at boot time. |
| 45 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | -Andi Kleen, Jul 2004 |