Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 157 insertions, 0 deletions

diff --git a/Documentation/x86/x86_64/mm.rst b/Documentation/x86/x86_64/mm.rst
new file mode 100644
index 000000000..9798676bb
--- /dev/null
+++ b/Documentation/x86/x86_64/mm.rst
@@ -0,0 +1,157 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+Memory Management
+=================
+
+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 way 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 PB 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
+  __________________|____________|__________________|_________|___________________________________________________________
+                    |            |                  |         |
+   0100000000000000 |  +64    PB | feffffffffffffff | ~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 | fffffbffffffffff |   ~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).
+
+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