d2f7cbe7b2
We map the EFI regions needed for runtime services non-contiguously, with preserved alignment on virtual addresses starting from -4G down for a total max space of 64G. This way, we provide for stable runtime services addresses across kernels so that a kexec'd kernel can still use them. Thus, they're mapped in a separate pagetable so that we don't pollute the kernel namespace. Add an efi= kernel command line parameter for passing miscellaneous options and chicken bits from the command line. While at it, add a chicken bit called "efi=old_map" which can be used as a fallback to the old runtime services mapping method in case there's some b0rkage with a particular EFI implementation (haha, it is hard to hold up the sarcasm here...). Also, add the UEFI RT VA space to Documentation/x86/x86_64/mm.txt. Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
39 lines
1.5 KiB
Plaintext
39 lines
1.5 KiB
Plaintext
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<previous description obsolete, deleted>
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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 [48:63] sign extension
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ffff800000000000 - ffff80ffffffffff (=40 bits) guard hole
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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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ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0
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ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space
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ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
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ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
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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 pages of
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the processes using the page fault handler, with init_level4_pgt as
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reference.
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Current X86-64 implementations only support 40 bits of address space,
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but we support up to 46 bits. This expands into MBZ space in the page tables.
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->trampoline_pgd:
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We map EFI runtime services in the aforementioned PGD in the virtual
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range of 64Gb (arbitrarily set, can be raised if needed)
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0xffffffef00000000 - 0xffffffff00000000
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-Andi Kleen, Jul 2004
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