Hi all, Today's linux-next merge of the kspp tree got a conflict in:
Documentation/x86/x86_64/mm.txt
between commits:
5b1290406579 ("x86/mm/doc: Clean up the x86-64 virtual memory layout
descriptions")
32b89760ddf4 ("x86/mm/doc: Enhance the x86-64 virtual memory layout
descriptions")
from the tip tree and commit:
afaef01c0015 ("x86/entry: Add STACKLEAK erasing the kernel stack at the end
of syscalls")
from the kspp tree.
I fixed it up (see below - could probably be done better) and can carry
the fix as necessary. This is now fixed as far as linux-next is
concerned, but any non trivial conflicts should be mentioned to your
upstream maintainer when your tree is submitted for merging. You may
also want to consider cooperating with the maintainer of the
conflicting tree to minimise any particularly complex conflicts.
--
Cheers,
Stephen Rothwell
diff --cc Documentation/x86/x86_64/mm.txt
index 702898633b00,600bc2afa27d..000000000000
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@@ -1,124 -1,57 +1,126 @@@
+====================================================
+Complete virtual memory map with 4-level page tables
+====================================================
-Virtual memory map with 4 level page tables:
-
-0000000000000000 - 00007fffffffffff (=47 bits) 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 ...
- 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
-[fixmap start] - ffffffffff5fffff kernel-internal fixmap range
-ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI
-ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
+Notes:
+
+ - Negative addresses such as "-23 TB" are absolute addresses in bytes,
counted down
+ from the top of the 64-bit address space. It's easier to understand the
layout
+ when seen both in absolute addresses and in distance-from-top notation.
+
+ For example 0xffffe90000000000 == -23 TB, it's 23 TB lower than the top of
the
+ 64-bit address space (ffffffffffffffff).
+
+ Note that as we get closer to the top of the address space, the notation
changes
+ from TB to GB and then MB/KB.
+
+ - "16M TB" might look weird at first sight, but it's an easier to visualize
size
+ notation than "16 EB", which few will recognize at first sight as 16
exabytes.
+ It also shows it nicely how incredibly large 64-bit address space is.
+
+========================================================================================================================
+ Start addr | Offset | End addr | Size | VM area
description
+========================================================================================================================
+ | | | |
+ 0000000000000000 | 0 | 00007fffffffffff | 128 TB | user-space
virtual memory, different per mm
+__________________|____________|__________________|_________|___________________________________________________________
+ | | | |
+ 0000800000000000 | +128 TB | ffff7fffffffffff | ~16M TB | ... huge,
almost 64 bits wide hole of non-canonical
+ | | | | virtual
memory addresses up to the -128 TB
+ | | | | starting
offset of kernel mappings.
+__________________|____________|__________________|_________|___________________________________________________________
+ |
+ | Kernel-space
virtual memory, shared between all processes:
+____________________________________________________________|___________________________________________________________
+ | | | |
+ ffff800000000000 | -128 TB | ffff87ffffffffff | 8 TB | ... guard hole,
also reserved for hypervisor
+ ffff880000000000 | -120 TB | ffffc7ffffffffff | 64 TB | direct mapping
of all physical memory (page_offset_base)
+ ffffc80000000000 | -56 TB | ffffc8ffffffffff | 1 TB | ... unused hole
+ ffffc90000000000 | -55 TB | ffffe8ffffffffff | 32 TB | vmalloc/ioremap
space (vmalloc_base)
+ ffffe90000000000 | -23 TB | ffffe9ffffffffff | 1 TB | ... unused hole
+ ffffea0000000000 | -22 TB | ffffeaffffffffff | 1 TB | virtual memory
map (vmemmap_base)
+ ffffeb0000000000 | -21 TB | ffffebffffffffff | 1 TB | ... unused hole
+ ffffec0000000000 | -20 TB | fffffbffffffffff | 16 TB | KASAN shadow
memory
+ fffffc0000000000 | -4 TB | fffffdffffffffff | 2 TB | ... unused hole
+ | | | | vaddr_end for
KASLR
+ fffffe0000000000 | -2 TB | fffffe7fffffffff | 0.5 TB | cpu_entry_area
mapping
+ fffffe8000000000 | -1.5 TB | fffffeffffffffff | 0.5 TB | LDT remap for
PTI
+ ffffff0000000000 | -1 TB | ffffff7fffffffff | 0.5 TB | %esp fixup
stacks
+__________________|____________|__________________|_________|____________________________________________________________
+ |
+ | Identical
layout to the 47-bit one from here on:
+____________________________________________________________|____________________________________________________________
+ | | | |
+ ffffff8000000000 | -512 GB | ffffffeeffffffff | 444 GB | ... unused hole
+ ffffffef00000000 | -68 GB | fffffffeffffffff | 64 GB | EFI region
mapping space
+ ffffffff00000000 | -4 GB | ffffffff7fffffff | 2 GB | ... unused hole
+ ffffffff80000000 | -2 GB | ffffffff9fffffff | 512 MB | kernel text
mapping, mapped to physical address 0
+ ffffffff80000000 |-2048 MB | | |
+ ffffffffa0000000 |-1536 MB | fffffffffeffffff | 1520 MB | module mapping
space
+ ffffffffff000000 | -16 MB | | |
+ FIXADDR_START | ~-11 MB | ffffffffff5fffff | ~0.5 MB | kernel-internal
fixmap range, variable size and offset
+ ffffffffff600000 | -10 MB | ffffffffff600fff | 4 kB | legacy vsyscall
ABI
+ ffffffffffe00000 | -2 MB | ffffffffffffffff | 2 MB | ... unused hole
+__________________|____________|__________________|_________|___________________________________________________________
+ STACKLEAK_POISON value in this last hole: ffffffffffff4111
-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 - 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 ...
- 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
-[fixmap start] - ffffffffff5fffff kernel-internal fixmap range
-ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI
-ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
+
+====================================================
+Complete virtual memory map with 5-level page tables
+====================================================
+
+Notes:
+
+ - With 56-bit addresses, user-space memory gets expanded by a factor of 512x,
+ from 0.125 PB to 64 PB. All kernel mappings shift down to the -64 PT
starting
+ offset and many of the regions expand to support the much larger physical
+ memory supported.
+
+========================================================================================================================
+ Start addr | Offset | End addr | Size | VM area
description
+========================================================================================================================
+ | | | |
+ 0000000000000000 | 0 | 00ffffffffffffff | 64 PB | user-space
virtual memory, different per mm
+__________________|____________|__________________|_________|___________________________________________________________
+ | | | |
+ 0000800000000000 | +64 PB | ffff7fffffffffff | ~16K PB | ... huge, still
almost 64 bits wide hole of non-canonical
+ | | | | virtual
memory addresses up to the -128 TB
+ | | | | starting
offset of kernel mappings.
+__________________|____________|__________________|_________|___________________________________________________________
+ |
+ | Kernel-space
virtual memory, shared between all processes:
+____________________________________________________________|___________________________________________________________
+ | | | |
+ ff00000000000000 | -64 PB | ff0fffffffffffff | 4 PB | ... guard hole,
also reserved for hypervisor
+ ff10000000000000 | -60 PB | ff8fffffffffffff | 32 PB | direct mapping
of all physical memory (page_offset_base)
+ ff90000000000000 | -28 PB | ff9fffffffffffff | 4 PB | LDT remap for
PTI
+ ffa0000000000000 | -24 PB | ffd1ffffffffffff | 12.5 PB | vmalloc/ioremap
space (vmalloc_base)
+ ffd2000000000000 | -11.5 PB | ffd3ffffffffffff | 0.5 PB | ... unused hole
+ ffd4000000000000 | -11 PB | ffd5ffffffffffff | 0.5 PB | virtual memory
map (vmemmap_base)
+ ffd6000000000000 | -10.5 PB | ffdeffffffffffff | 2.25 PB | ... unused hole
+ ffdf000000000000 | -8.25 PB | fffffdffffffffff | ~8 PB | KASAN shadow
memory
+ fffffc0000000000 | -4 TB | fffffdffffffffff | 2 TB | ... unused hole
+ | | | | vaddr_end for
KASLR
+ fffffe0000000000 | -2 TB | fffffe7fffffffff | 0.5 TB | cpu_entry_area
mapping
+ fffffe8000000000 | -1.5 TB | fffffeffffffffff | 0.5 TB | ... unused hole
+ ffffff0000000000 | -1 TB | ffffff7fffffffff | 0.5 TB | %esp fixup
stacks
+__________________|____________|__________________|_________|____________________________________________________________
+ |
+ | Identical
layout to the 47-bit one from here on:
+____________________________________________________________|____________________________________________________________
+ | | | |
+ ffffff8000000000 | -512 GB | ffffffeeffffffff | 444 GB | ... unused hole
+ ffffffef00000000 | -68 GB | fffffffeffffffff | 64 GB | EFI region
mapping space
+ ffffffff00000000 | -4 GB | ffffffff7fffffff | 2 GB | ... unused hole
+ ffffffff80000000 | -2 GB | ffffffff9fffffff | 512 MB | kernel text
mapping, mapped to physical address 0
+ ffffffff80000000 |-2048 MB | | |
+ ffffffffa0000000 |-1536 MB | fffffffffeffffff | 1520 MB | module mapping
space
+ ffffffffff000000 | -16 MB | | |
+ FIXADDR_START | ~-11 MB | ffffffffff5fffff | ~0.5 MB | kernel-internal
fixmap range, variable size and offset
+ ffffffffff600000 | -10 MB | ffffffffff600fff | 4 kB | legacy vsyscall
ABI
+ ffffffffffe00000 | -2 MB | ffffffffffffffff | 2 MB | ... unused hole
+__________________|____________|__________________|_________|___________________________________________________________
+ STACKLEAK_POISON value in this last hole: ffffffffffff4111
Architecture defines a 64-bit virtual address. Implementations can support
less. Currently supported are 48- and 57-bit virtual addresses. Bits 63
pgpXgom4lTfV2.pgp
Description: OpenPGP digital signature
