28.3. Memory Management |
您所在的位置：网站首页 › vmalloc_user › 28.3. Memory Management |
|
28.3.2. 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 |
| CopyRight 2018-2019 办公设备维修网 版权所有 豫ICP备15022753号-3 |