forked from Minki/linux
9a3b7e5e65
Commit:f5a40711fa("x86/mm: Set MODULES_END to 0xffffffffff000000") changed MODULES_END back to a fixed value, but didn't update the documentation of memory layout for 4-level paging. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes:f5a40711fa("x86/mm: Set MODULES_END to 0xffffffffff000000") Link: http://lkml.kernel.org/r/20180402121025.10244-1-kirill.shutemov@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
80 lines
3.9 KiB
Plaintext
80 lines
3.9 KiB
Plaintext
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Virtual memory map with 4 level page tables:
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0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm
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hole caused by [47:63] sign extension
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ffff800000000000 - ffff87ffffffffff (=43 bits) guard hole, reserved for hypervisor
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ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory
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ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole
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ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space
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ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole
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ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB)
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... unused hole ...
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ffffec0000000000 - fffffbffffffffff (=44 bits) kasan shadow memory (16TB)
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... unused hole ...
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vaddr_end for KASLR
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fffffe0000000000 - fffffe7fffffffff (=39 bits) cpu_entry_area mapping
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fffffe8000000000 - fffffeffffffffff (=39 bits) LDT remap for PTI
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ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
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... unused hole ...
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ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space
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... unused hole ...
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ffffffff80000000 - ffffffff9fffffff (=512 MB) kernel text mapping, from phys 0
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ffffffffa0000000 - fffffffffeffffff (1520 MB) module mapping space
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[fixmap start] - ffffffffff5fffff kernel-internal fixmap range
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ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI
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ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
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Virtual memory map with 5 level page tables:
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0000000000000000 - 00ffffffffffffff (=56 bits) user space, different per mm
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hole caused by [56:63] sign extension
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ff00000000000000 - ff0fffffffffffff (=52 bits) guard hole, reserved for hypervisor
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ff10000000000000 - ff8fffffffffffff (=55 bits) direct mapping of all phys. memory
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ff90000000000000 - ff9fffffffffffff (=52 bits) LDT remap for PTI
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ffa0000000000000 - ffd1ffffffffffff (=54 bits) vmalloc/ioremap space (12800 TB)
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ffd2000000000000 - ffd3ffffffffffff (=49 bits) hole
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ffd4000000000000 - ffd5ffffffffffff (=49 bits) virtual memory map (512TB)
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... unused hole ...
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ffdf000000000000 - fffffc0000000000 (=53 bits) kasan shadow memory (8PB)
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... unused hole ...
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vaddr_end for KASLR
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fffffe0000000000 - fffffe7fffffffff (=39 bits) cpu_entry_area mapping
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... unused hole ...
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ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
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... unused hole ...
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ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space
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... unused hole ...
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ffffffff80000000 - ffffffff9fffffff (=512 MB) kernel text mapping, from phys 0
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ffffffffa0000000 - fffffffffeffffff (1520 MB) module mapping space
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[fixmap start] - ffffffffff5fffff kernel-internal fixmap range
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ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI
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ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
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Architecture defines a 64-bit virtual address. Implementations can support
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less. Currently supported are 48- and 57-bit virtual addresses. Bits 63
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through to the most-significant implemented bit are sign extended.
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This causes hole between user space and kernel addresses if you interpret them
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as unsigned.
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The direct mapping covers all memory in the system up to the highest
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memory address (this means in some cases it can also include PCI memory
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holes).
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vmalloc space is lazily synchronized into the different PML4/PML5 pages of
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the processes using the page fault handler, with init_top_pgt as
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reference.
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We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual
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memory window (this size is arbitrary, it can be raised later if needed).
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The mappings are not part of any other kernel PGD and are only available
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during EFI runtime calls.
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Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all
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physical memory, vmalloc/ioremap space and virtual memory map are randomized.
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Their order is preserved but their base will be offset early at boot time.
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Be very careful vs. KASLR when changing anything here. The KASLR address
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range must not overlap with anything except the KASAN shadow area, which is
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correct as KASAN disables KASLR.
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