Re: [PATCH 23/27] Documentation: x86: convert x86_64/mm.txt to reST

From: Mauro Carvalho Chehab
Date: Sat Apr 27 2019 - 14:35:20 EST

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In reply to: Changbin Du: "[PATCH 23/27] Documentation: x86: convert x86_64/mm.txt to reST"
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Em Fri, 26 Apr 2019 23:31:46 +0800
Changbin Du <changbin.du@xxxxxxxxx> escreveu:

> This converts the plain text documentation to reStructuredText format and
> add it to Sphinx TOC tree. No essential content change.
>
> Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
> ---
> Documentation/x86/x86_64/index.rst | 1 +
> Documentation/x86/x86_64/mm.rst | 161 +++++++++++++++++++++++++++++
> Documentation/x86/x86_64/mm.txt | 153 ---------------------------
> 3 files changed, 162 insertions(+), 153 deletions(-)
> create mode 100644 Documentation/x86/x86_64/mm.rst
> delete mode 100644 Documentation/x86/x86_64/mm.txt

This is another patch that requires you to rebase on the top of the latest
version. Applying it against linux-next causes troubles:

import_patch --batch --nocheck --tested --nomedia && make htmldocs
Applying patch patches/858900ba6cfdc922e6aac83f519030e09e03789a_23_27_documentation_x86_convert_x86_64_mm_txt_to_rest.patch
patching file Documentation/x86/x86_64/index.rst
patching file Documentation/x86/x86_64/mm.rst
patching file Documentation/x86/x86_64/mm.txt
Hunk #1 FAILED at 1.
Not deleting file Documentation/x86/x86_64/mm.txt as content differs from patch
1 out of 1 hunk FAILED -- rejects in file Documentation/x86/x86_64/mm.txt
Patch patches/858900ba6cfdc922e6aac83f519030e09e03789a_23_27_documentation

This specific issue is likely caused by this change:

Fixes: 89502a019790 ("x86/mm: Fix the 56-bit addresses memory map in Documentation/x86/x86_64/mm.txt")

Except for that, the patch looks ok for me. So, after rebasing:

Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@xxxxxxxxxx>

>
> diff --git a/Documentation/x86/x86_64/index.rst b/Documentation/x86/x86_64/index.rst
> index ddfa1f9d4193..4b65d29ef459 100644
> --- a/Documentation/x86/x86_64/index.rst
> +++ b/Documentation/x86/x86_64/index.rst
> @@ -9,3 +9,4 @@ x86_64 Support
>
> boot-options
> uefi
> + mm
> diff --git a/Documentation/x86/x86_64/mm.rst b/Documentation/x86/x86_64/mm.rst
> new file mode 100644
> index 000000000000..52020577b8de
> --- /dev/null
> +++ b/Documentation/x86/x86_64/mm.rst
> @@ -0,0 +1,161 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +================
> +Memory Managment
> +================
> +
> +Complete virtual memory map with 4-level page tables
> +====================================================
> +
> +.. note::
> +
> + - 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 | ffff887fffffffff | 0.5 TB | LDT remap for PTI
> + ffff888000000000 | -119.5 TB | ffffc87fffffffff | 64 TB | direct mapping of all physical memory (page_offset_base)
> + ffffc88000000000 | -55.5 TB | ffffc8ffffffffff | 0.5 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
> + __________________|____________|__________________|_________|____________________________________________________________
> + |
> + | Identical layout to the 56-bit one from here on:
> + ____________________________________________________________|____________________________________________________________
> + | | | |
> + 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
> + 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
> + __________________|____________|__________________|_________|___________________________________________________________
> +
> +
> +Complete virtual memory map with 5-level page tables
> +====================================================
> +
> +.. note::
> +
> + - 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 -64 PB
> + | | | | 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 | ff10ffffffffffff | 0.25 PB | LDT remap for PTI
> + ff11000000000000 | -59.75 PB | ff90ffffffffffff | 32 PB | direct mapping of all physical memory (page_offset_base)
> + ff91000000000000 | -27.75 PB | ff9fffffffffffff | 3.75 PB | ... unused hole
> + 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
> + __________________|____________|__________________|_________|____________________________________________________________
> + |
> + | Identical layout to the 47-bit one from here on:
> + ____________________________________________________________|____________________________________________________________
> + | | | |
> + 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
> + 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
> + __________________|____________|__________________|_________|___________________________________________________________
> +
> +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 sign extended.
> +This causes hole between user space and kernel addresses if you interpret them
> +as unsigned.
> +
> +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/PML5 pages of
> +the processes using the page fault handler, with init_top_pgt as
> +reference.
> +
> +We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual
> +memory window (this size is arbitrary, it can be raised later if needed).
> +The mappings are not part of any other kernel PGD and are only available
> +during EFI runtime calls.
> +
> +Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all
> +physical memory, vmalloc/ioremap space and virtual memory map are randomized.
> +Their order is preserved but their base will be offset early at boot time.
> +
> +Be very careful vs. KASLR when changing anything here. The KASLR address
> +range must not overlap with anything except the KASAN shadow area, which is
> +correct as KASAN disables KASLR.
> +
> +For both 4- and 5-level layouts, the STACKLEAK_POISON value in the last 2MB
> +hole: ffffffffffff4111
> diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
> deleted file mode 100644
> index 804f9426ed17..000000000000
> --- a/Documentation/x86/x86_64/mm.txt
> +++ /dev/null
> @@ -1,153 +0,0 @@
> -====================================================
> -Complete virtual memory map with 4-level page tables
> -====================================================
> -
> -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 | ffff887fffffffff | 0.5 TB | LDT remap for PTI
> - ffff888000000000 | -119.5 TB | ffffc87fffffffff | 64 TB | direct mapping of all physical memory (page_offset_base)
> - ffffc88000000000 | -55.5 TB | ffffc8ffffffffff | 0.5 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
> -__________________|____________|__________________|_________|____________________________________________________________
> - |
> - | Identical layout to the 56-bit one from here on:
> -____________________________________________________________|____________________________________________________________
> - | | | |
> - 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
> - 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
> -__________________|____________|__________________|_________|___________________________________________________________
> -
> -
> -====================================================
> -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 -64 PB
> - | | | | 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 | ff10ffffffffffff | 0.25 PB | LDT remap for PTI
> - ff11000000000000 | -59.75 PB | ff90ffffffffffff | 32 PB | direct mapping of all physical memory (page_offset_base)
> - ff91000000000000 | -27.75 PB | ff9fffffffffffff | 3.75 PB | ... unused hole
> - 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
> -__________________|____________|__________________|_________|____________________________________________________________
> - |
> - | Identical layout to the 47-bit one from here on:
> -____________________________________________________________|____________________________________________________________
> - | | | |
> - 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
> - 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
> -__________________|____________|__________________|_________|___________________________________________________________
> -
> -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 sign extended.
> -This causes hole between user space and kernel addresses if you interpret them
> -as unsigned.
> -
> -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/PML5 pages of
> -the processes using the page fault handler, with init_top_pgt as
> -reference.
> -
> -We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual
> -memory window (this size is arbitrary, it can be raised later if needed).
> -The mappings are not part of any other kernel PGD and are only available
> -during EFI runtime calls.
> -
> -Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all
> -physical memory, vmalloc/ioremap space and virtual memory map are randomized.
> -Their order is preserved but their base will be offset early at boot time.
> -
> -Be very careful vs. KASLR when changing anything here. The KASLR address
> -range must not overlap with anything except the KASAN shadow area, which is
> -correct as KASAN disables KASLR.
> -
> -For both 4- and 5-level layouts, the STACKLEAK_POISON value in the last 2MB
> -hole: ffffffffffff4111

Thanks,
Mauro

Next message: Mauro Carvalho Chehab: "Re: [PATCH 24/27] Documentation: x86: convert x86_64/5level-paging.txt to reST"
Previous message: Mauro Carvalho Chehab: "Re: [PATCH 22/27] Documentation: x86: convert x86_64/uefi.txt to reST"
In reply to: Changbin Du: "[PATCH 23/27] Documentation: x86: convert x86_64/mm.txt to reST"
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