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arm64: mm: tidy up top of kernel VA space

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Tidy up the way the top of the kernel VA space is organized, by mirroring
the 256 MB region we have below the vmalloc space, and populating it top
down with the PCI I/O space, some guard regions, and the fixmap region.
The latter region is itself populated top down, and today only covers
about 4 MB, and so 224 MB is ample, and no guard region is therefore
required.

The resulting layout is identical between 48-bit/4k and 52-bit/64k
configurations.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Link: https://lore.kernel.org/r/20201008153602.9467-5-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel 2020-10-08 17:36:02 +02:00 committed by Catalin Marinas
parent 8c96400d6a
commit 9ad7c6d5e7
3 changed files with 13 additions and 15 deletions
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22
Documentation/arm64/memory.rst
View file

@ -35,12 +35,11 @@ AArch64 Linux memory layout with 4KB pages + 4 levels (48-bit)::
[ ffff600000000000 ffff7fffffffffff ] 32TB [ kasan shadow region ]
ffff800000000000 ffff800007ffffff 128MB bpf jit region
ffff800008000000 ffff80000fffffff 128MB modules
ffff800010000000 fffffbffbffeffff 123TB vmalloc
fffffbffbfff0000 fffffbfffe7f8fff ~998MB [guard region]
fffffbfffe7f9000 fffffbfffebfffff 4124KB fixed mappings
fffffbfffec00000 fffffbfffedfffff 2MB [guard region]
fffffbfffee00000 fffffbffffdfffff 16MB PCI I/O space
fffffbffffe00000 fffffbffffffffff 2MB [guard region]
ffff800010000000 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]
@ -54,12 +53,11 @@ AArch64 Linux memory layout with 64KB pages + 3 levels (52-bit with HW support):
[ fffd800000000000 ffff7fffffffffff ] 512TB [ kasan shadow region ]
ffff800000000000 ffff800007ffffff 128MB bpf jit region
ffff800008000000 ffff80000fffffff 128MB modules
ffff800010000000 fffff81ffffeffff 120TB vmalloc
fffff81fffff0000 fffffbfffe38ffff ~3TB [guard region]
fffffbfffe390000 fffffbfffebfffff 4544KB fixed mappings
fffffbfffec00000 fffffbfffedfffff 2MB [guard region]
fffffbfffee00000 fffffbffffdfffff 16MB PCI I/O space
fffffbffffe00000 fffffbffffffffff 2MB [guard region]
ffff800010000000 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]

4
arch/arm64/include/asm/memory.h
View file

@ -52,9 +52,9 @@
#define MODULES_VSIZE (SZ_128M)
#define VMEMMAP_START (-(UL(1) << (VA_BITS - VMEMMAP_SHIFT)))
#define VMEMMAP_END (VMEMMAP_START + VMEMMAP_SIZE)
#define PCI_IO_END (VMEMMAP_START - SZ_2M)
#define PCI_IO_END (VMEMMAP_START - SZ_8M)
#define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE)
#define FIXADDR_TOP (PCI_IO_START - SZ_2M)
#define FIXADDR_TOP (VMEMMAP_START - SZ_32M)
#if VA_BITS > 48
#define VA_BITS_MIN (48)

2
arch/arm64/include/asm/pgtable.h
View file

@ -22,7 +22,7 @@
* and fixed mappings
*/
#define VMALLOC_START (MODULES_END)
#define VMALLOC_END (- PUD_SIZE - VMEMMAP_SIZE - SZ_64K)
#define VMALLOC_END (VMEMMAP_START - SZ_256M)
#define vmemmap ((struct page *)VMEMMAP_START - (memstart_addr >> PAGE_SHIFT))