Commit 5b129040 authored by Baoquan He's avatar Baoquan He Committed by Ingo Molnar
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x86/mm/doc: Clean up the x86-64 virtual memory layout descriptions 



In Documentation/x86/x86_64/mm.txt, the description of the x86-64 virtual
memory layout has become a confusing hodgepodge of inconsistencies:

 - there's a hard to read mixture of 'TB' and 'bits' notation
 - the entries sometimes mention a size in the description and sometimes not
 - sometimes they list holes by address, sometimes only as an 'unused hole' line

So make it all a coherent, readable, well organized description.

Signed-off-by: default avatarBaoquan He <bhe@redhat.com>
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@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: corbet@lwn.net
Cc: linux-doc@vger.kernel.org
Cc: thgarnie@google.com
Link: http://lkml.kernel.org/r/20181006084327.27467-3-bhe@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 06d4a462

Documentation/x86/x86_64/mm.txt

+42 −42
Original line number Diff line number Diff line 


Virtual memory map with 4 level page tables:



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

0000000000000000 - 00007fffffffffff (=47 bits,   128 TB) user space, different per mm

				    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

ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space

ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole

ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB)

... unused hole ...

ffffec0000000000 - fffffbffffffffff (=44 bits) kasan shadow memory (16TB)

... unused hole ...

ffff800000000000 - ffff87ffffffffff (=43 bits,     8 TB) guard hole, reserved for hypervisor

ffff880000000000 - ffffc7ffffffffff (=46 bits,    64 TB) direct mapping of all phys. memory (page_offset_base)

ffffc80000000000 - ffffc8ffffffffff (=40 bits,     1 TB) unused hole

ffffc90000000000 - ffffe8ffffffffff (=45 bits,    32 TB) vmalloc/ioremap space (vmalloc_base)

ffffe90000000000 - ffffe9ffffffffff (=40 bits,     1 TB) unused hole

ffffea0000000000 - ffffeaffffffffff (=40 bits,     1 TB) virtual memory map (vmemmap_base)

ffffeb0000000000 - ffffebffffffffff (=40 bits,     1 TB) unused hole

ffffec0000000000 - fffffbffffffffff (=44 bits,    16 TB) kasan shadow memory

fffffc0000000000 - fffffdffffffffff (=41 bits,     2 TB) unused hole

				    vaddr_end for KASLR

fffffe0000000000 - fffffe7fffffffff (=39 bits) cpu_entry_area mapping

fffffe8000000000 - fffffeffffffffff (=39 bits) LDT remap for PTI

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 - fffffffffeffffff (1520 MB) module mapping space

fffffe0000000000 - fffffe7fffffffff (=39 bits,   512 GB) cpu_entry_area mapping

fffffe8000000000 - fffffeffffffffff (=39 bits,   512 GB) LDT remap for PTI

ffffff0000000000 - ffffff7fffffffff (=39 bits,   512 GB) %esp fixup stacks

ffffff8000000000 - fffffffeefffffff (~39 bits,  ~507 GB) unused hole

ffffffef00000000 - fffffffeffffffff (=36 bits,    64 GB) EFI region mapping space

ffffffff00000000 - ffffffff7fffffff (=31 bits,     2 GB) unused hole

ffffffff80000000 - ffffffff9fffffff (=29 bits,   512 MB) kernel text mapping, from phys 0

ffffffffa0000000 - fffffffffeffffff (~31 bits,  1520 MB) module mapping space

[fixmap start]   - ffffffffff5fffff kernel-internal fixmap range

ffffffffff600000 - ffffffffff600fff (             =4 kB) legacy vsyscall ABI

ffffffffffe00000 - ffffffffffffffff (             =2 MB) unused hole



Virtual memory map with 5 level page tables:



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

0000000000000000 - 00ffffffffffffff (=56 bits,    64 PB) 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 - ff9fffffffffffff (=52 bits) LDT remap for PTI

ffa0000000000000 - ffd1ffffffffffff (=54 bits) vmalloc/ioremap space (12800 TB)

ffd2000000000000 - ffd3ffffffffffff (=49 bits) hole

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

... unused hole ...

ffdf000000000000 - fffffc0000000000 (=53 bits) kasan shadow memory (8PB)

... unused hole ...

ff00000000000000 - ff0fffffffffffff (=52 bits,     4 PB) guard hole, reserved for hypervisor

ff10000000000000 - ff8fffffffffffff (=55 bits,    32 PB) direct mapping of all phys. memory (page_offset_base)

ff90000000000000 - ff9fffffffffffff (=52 bits,     4 PB) LDT remap for PTI

ffa0000000000000 - ffd1ffffffffffff (=53 bits, 12800 TB) vmalloc/ioremap space (vmalloc_base)

ffd2000000000000 - ffd3ffffffffffff (=49 bits,   512 TB) unused hole

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

ffd6000000000000 - ffdeffffffffffff (~51 bits,  2304 TB) unused hole

ffdf000000000000 - fffffdffffffffff (~53 bits,    ~8 PB) kasan shadow memory

fffffc0000000000 - fffffdffffffffff (=41 bits,     2 TB) unused hole

				    vaddr_end for KASLR

fffffe0000000000 - fffffe7fffffffff (=39 bits) cpu_entry_area mapping

... 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 - fffffffffeffffff (1520 MB) module mapping space

fffffe0000000000 - fffffe7fffffffff (=39 bits,   512 GB) cpu_entry_area mapping

fffffe8000000000 - fffffeffffffffff (=39 bits,   512 GB) unused hole

ffffff0000000000 - ffffff7fffffffff (=39 bits,   512 GB) %esp fixup stacks

ffffff8000000000 - ffffffeeffffffff (~39 bits,   444 GB) unused hole

ffffffef00000000 - fffffffeffffffff (=36 bits,    64 GB) EFI region mapping space

ffffffff00000000 - ffffffff7fffffff (31 bits,      2 GB) unused hole

ffffffff80000000 - ffffffff9fffffff (=29 bits,   512 MB) kernel text mapping, from phys 0

ffffffffa0000000 - fffffffffeffffff (~31 bits,  1520 MB) module mapping space

[fixmap start]   - ffffffffff5fffff kernel-internal fixmap range

ffffffffff600000 - ffffffffff600fff (             =4 kB) legacy vsyscall ABI

ffffffffffe00000 - ffffffffffffffff (             =2 MB) unused hole

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