Re: [PATCH v2 7/9] riscv: Align the sv39 linear map to 16 GiB

Alexandre Ghiti
2024-11-05T13:58:32Z

On 22/10/2024 03:57, Samuel Holland wrote:
> The KASAN implementation on RISC-V requires the shadow memory for the
> vmemmap and linear map regions to be aligned to a PMD boundary (1 GiB).

PUD boundary

> For KASAN_GENERIC (KASAN_SHADOW_SCALE_SHIFT == 3), this enforces 8 GiB
> alignment for the memory regions themselves. KASAN_SW_TAGS uses 16-byte
> granules (KASAN_SHADOW_SCALE_SHIFT == 4), so now the memory regions must
> be aligned to a 16 GiB boundary.
>
> Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
> ---
>
> (no changes since v1)
>
> Documentation/arch/riscv/vm-layout.rst | 10 +++++-----
> arch/riscv/include/asm/page.h | 2 +-
> 2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/arch/riscv/vm-layout.rst b/Documentation/arch/riscv/vm-layout.rst
> index eabec99b5852..c0778c421b34 100644
> --- a/Documentation/arch/riscv/vm-layout.rst
> +++ b/Documentation/arch/riscv/vm-layout.rst
> @@ -47,11 +47,11 @@ RISC-V Linux Kernel SV39
> | Kernel-space virtual memory, shared between all processes:
> ____________________________________________________________|___________________________________________________________
> | | | |
> - 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
> + ffffffc2fea00000 | -244 GB | ffffffc2feffffff | 6 MB | fixmap
> + ffffffc2ff000000 | -244 GB | ffffffc2ffffffff | 16 MB | PCI io
> + ffffffc300000000 | -244 GB | ffffffc3ffffffff | 4 GB | vmemmap
> + ffffffc400000000 | -240 GB | ffffffd3ffffffff | 64 GB | vmalloc/ioremap space
> + ffffffd400000000 | -176 GB | fffffff3ffffffff | 128 GB | direct mapping of all physical memory
> | | | |
> fffffff700000000 | -36 GB | fffffffeffffffff | 32 GB | kasan
> __________________|____________|__________________|_________|____________________________________________________________
> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
> index 32d308a3355f..6e2f79cf77c5 100644
> --- a/arch/riscv/include/asm/page.h
> +++ b/arch/riscv/include/asm/page.h
> @@ -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(0xffffffd600000000, UL)
> +#define PAGE_OFFSET_L3 _AC(0xffffffd400000000, UL)
> #else
> #define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL)
> #endif /* CONFIG_64BIT */

Other than the nit above (that I think should be fixed though), you can add:

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex