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riscv: Extend sv39 linear mapping max size to 128G

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This harmonizes all virtual addressing modes which can now all map
(PGDIR_SIZE * PTRS_PER_PGD) / 4 of physical memory.

The RISCV implementation of KASAN requires that the boundary between
shallow mappings are aligned on an 8G boundary. In this case we need
VMALLOC_START to be 8G aligned. So although we only need to move the
start of the linear mapping down by 4GiB to allow 128GiB to be mapped,
we actually move it down by 8GiB (creating a 4GiB hole between the
linear mapping and KASAN shadow space) to maintain the alignment
requirement.

Signed-off-by: Stuart Menefy <stuart.menefy@codasip.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240630110550.1731929-1-stuart.menefy@codasip.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Stuart Menefy 2024-06-30 12:05:49 +01:00 committed by Palmer Dabbelt
parent 3aa1a7d013
commit 5c8405d763
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2 changed files with 7 additions and 6 deletions
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11
Documentation/arch/riscv/vm-layout.rst
View File

@ -47,11 +47,12 @@ RISC-V Linux Kernel SV39
| Kernel-space virtual memory, shared between all processes:
____________________________________________________________|___________________________________________________________
| | | |
ffffffc6fea00000 | -228 GB | ffffffc6feffffff | 6 MB | fixmap
ffffffc6ff000000 | -228 GB | ffffffc6ffffffff | 16 MB | PCI io
ffffffc700000000 | -228 GB | ffffffc7ffffffff | 4 GB | vmemmap
ffffffc800000000 | -224 GB | ffffffd7ffffffff | 64 GB | vmalloc/ioremap space
ffffffd800000000 | -160 GB | fffffff6ffffffff | 124 GB | direct mapping of all physical memory
ffffffc4fea00000 | -236 GB | ffffffc4feffffff | 6 MB | fixmap
ffffffc4ff000000 | -236 GB | ffffffc4ffffffff | 16 MB | PCI io
ffffffc500000000 | -236 GB | ffffffc5ffffffff | 4 GB | vmemmap
ffffffc600000000 | -232 GB | ffffffd5ffffffff | 64 GB | vmalloc/ioremap space
ffffffd600000000 | -168 GB | fffffff5ffffffff | 128 GB | direct mapping of all physical memory
| | | |
fffffff700000000 | -36 GB | fffffffeffffffff | 32 GB | kasan
__________________|____________|__________________|_________|____________________________________________________________
|

2
arch/riscv/include/asm/page.h
View File

@ -37,7 +37,7 @@
* define the PAGE_OFFSET value for SV48 and SV39.
*/
#define PAGE_OFFSET_L4 _AC(0xffffaf8000000000, UL)
#define PAGE_OFFSET_L3 _AC(0xffffffd800000000, UL)
#define PAGE_OFFSET_L3 _AC(0xffffffd600000000, UL)
#else
#define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL)
#endif /* CONFIG_64BIT */