| |
| 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 - ffff887fffffffff (=39 bits) LDT remap for PTI |
| ffff888000000000 - ffffc87fffffffff (=64 TB) direct mapping of all phys. memory |
| ffffc88000000000 - ffffc8ffffffffff (=39 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 - [fixmap start] (~1526 MB) module mapping space (variable) |
| [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 |
| hole caused by [56:63] sign extension |
| ff00000000000000 - ff0fffffffffffff (=52 bits) guard hole, reserved for hypervisor |
| ff10000000000000 - ff10ffffffffffff (=48 bits) LDT remap for PTI |
| ff11000000000000 - ff90ffffffffffff (=55 bits) direct mapping of all phys. memory |
| ff91000000000000 - ff9fffffffffffff (=3840 TB) hole |
| 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 |
| |
| 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. |
