Unverified Commit 5c8405d7 authored by Stuart Menefy's avatar Stuart Menefy Committed by Palmer Dabbelt
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riscv: Extend sv39 linear mapping max size to 128G 



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: default avatarStuart Menefy <stuart.menefy@codasip.com>
Reviewed-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240630110550.1731929-1-stuart.menefy@codasip.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 3aa1a7d0

Documentation/arch/riscv/vm-layout.rst

+6 −5
Original line number Diff line number Diff line
@@ -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

  __________________|____________|__________________|_________|____________________________________________________________

                                                              |

arch/riscv/include/asm/page.h

+1 −1
Original line number Diff line number Diff line
@@ -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 */