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Diffstat (limited to 'Documentation/arch/arm64/memory.rst')
| -rw-r--r-- | Documentation/arch/arm64/memory.rst | 75 |
1 files changed, 4 insertions, 71 deletions
diff --git a/Documentation/arch/arm64/memory.rst b/Documentation/arch/arm64/memory.rst index 55a55f30eed8..678fbb418c3a 100644 --- a/Documentation/arch/arm64/memory.rst +++ b/Documentation/arch/arm64/memory.rst @@ -18,77 +18,10 @@ ARMv8.2 adds optional support for Large Virtual Address space. This is only available when running with a 64KB page size and expands the number of descriptors in the first level of translation. -User addresses have bits 63:48 set to 0 while the kernel addresses have -the same bits set to 1. TTBRx selection is given by bit 63 of the -virtual address. The swapper_pg_dir contains only kernel (global) -mappings while the user pgd contains only user (non-global) mappings. -The swapper_pg_dir address is written to TTBR1 and never written to -TTBR0. - - -AArch64 Linux memory layout with 4KB pages + 4 levels (48-bit):: - - Start End Size Use - ----------------------------------------------------------------------- - 0000000000000000 0000ffffffffffff 256TB user - ffff000000000000 ffff7fffffffffff 128TB kernel logical memory map - [ffff600000000000 ffff7fffffffffff] 32TB [kasan shadow region] - ffff800000000000 ffff80007fffffff 2GB modules - ffff800080000000 fffffbffefffffff 124TB vmalloc - fffffbfff0000000 fffffbfffdffffff 224MB fixed mappings (top down) - fffffbfffe000000 fffffbfffe7fffff 8MB [guard region] - fffffbfffe800000 fffffbffff7fffff 16MB PCI I/O space - fffffbffff800000 fffffbffffffffff 8MB [guard region] - fffffc0000000000 fffffdffffffffff 2TB vmemmap - fffffe0000000000 ffffffffffffffff 2TB [guard region] - - -AArch64 Linux memory layout with 64KB pages + 3 levels (52-bit with HW support):: - - Start End Size Use - ----------------------------------------------------------------------- - 0000000000000000 000fffffffffffff 4PB user - fff0000000000000 ffff7fffffffffff ~4PB kernel logical memory map - [fffd800000000000 ffff7fffffffffff] 512TB [kasan shadow region] - ffff800000000000 ffff80007fffffff 2GB modules - ffff800080000000 fffffbffefffffff 124TB vmalloc - fffffbfff0000000 fffffbfffdffffff 224MB fixed mappings (top down) - fffffbfffe000000 fffffbfffe7fffff 8MB [guard region] - fffffbfffe800000 fffffbffff7fffff 16MB PCI I/O space - fffffbffff800000 fffffbffffffffff 8MB [guard region] - fffffc0000000000 ffffffdfffffffff ~4TB vmemmap - ffffffe000000000 ffffffffffffffff 128GB [guard region] - - -Translation table lookup with 4KB pages:: - - +--------+--------+--------+--------+--------+--------+--------+--------+ - |63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0| - +--------+--------+--------+--------+--------+--------+--------+--------+ - | | | | | | - | | | | | v - | | | | | [11:0] in-page offset - | | | | +-> [20:12] L3 index - | | | +-----------> [29:21] L2 index - | | +---------------------> [38:30] L1 index - | +-------------------------------> [47:39] L0 index - +-------------------------------------------------> [63] TTBR0/1 - - -Translation table lookup with 64KB pages:: - - +--------+--------+--------+--------+--------+--------+--------+--------+ - |63 56|55 48|47 40|39 32|31 24|23 16|15 8|7 0| - +--------+--------+--------+--------+--------+--------+--------+--------+ - | | | | | - | | | | v - | | | | [15:0] in-page offset - | | | +----------> [28:16] L3 index - | | +--------------------------> [41:29] L2 index - | +-------------------------------> [47:42] L1 index (48-bit) - | [51:42] L1 index (52-bit) - +-------------------------------------------------> [63] TTBR0/1 - +TTBRx selection is given by bit 55 of the virtual address. The +swapper_pg_dir contains only kernel (global) mappings while the user pgd +contains only user (non-global) mappings. The swapper_pg_dir address is +written to TTBR1 and never written to TTBR0. When using KVM without the Virtualization Host Extensions, the hypervisor maps kernel pages in EL2 at a fixed (and potentially |