| Message ID | 20240630110550.1731929-1-stuart.menefy@codasip.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] riscv: Extend sv39 linear mapping max size to 128G | expand |
Hi Stuart, On Sun, Jun 30, 2024 at 1:06 PM Stuart Menefy <stuart.menefy@codasip.com> wrote: > > 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> > --- > > Changes since V1: > This is a modified version of the patch posted by Alexandre Ghiti > <alexghiti@rivosinc.com> [1]. That version moved the start of the > liner mapping by 4GiB, but was subsequently found to trigger a problem > in the KASAN code [2]. By moving the start address by 8GiB alignment > requiremenents are maintained. > > [1] https://lore.kernel.org/linux-riscv/20240514133614.87813-1-alexghiti@rivosinc.com/ > [2] https://lore.kernel.org/linux-riscv/4011b34a-1b86-42c7-aaf6-3bd297149f06@ghiti.fr/ > > --- > Documentation/arch/riscv/vm-layout.rst | 11 ++++++----- > arch/riscv/include/asm/page.h | 2 +- > 2 files changed, 7 insertions(+), 6 deletions(-) > > diff --git a/Documentation/arch/riscv/vm-layout.rst b/Documentation/arch/riscv/vm-layout.rst > index e476b4386bd9..077b968dcc81 100644 > --- a/Documentation/arch/riscv/vm-layout.rst > +++ b/Documentation/arch/riscv/vm-layout.rst > @@ -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 > __________________|____________|__________________|_________|____________________________________________________________ > | > diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h > index 115ac98b8d72..81d47fbbd927 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(0xffffffd800000000, UL) > +#define PAGE_OFFSET_L3 _AC(0xffffffd600000000, UL) > #else > #define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL) > #endif /* CONFIG_64BIT */ > -- > 2.43.0 > So the issue was with my patch, sorry! Your fix makes sense so you can add: Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Thanks, Alex
diff --git a/Documentation/arch/riscv/vm-layout.rst b/Documentation/arch/riscv/vm-layout.rst index e476b4386bd9..077b968dcc81 100644 --- a/Documentation/arch/riscv/vm-layout.rst +++ b/Documentation/arch/riscv/vm-layout.rst @@ -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 __________________|____________|__________________|_________|____________________________________________________________ | diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h index 115ac98b8d72..81d47fbbd927 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(0xffffffd800000000, UL) +#define PAGE_OFFSET_L3 _AC(0xffffffd600000000, UL) #else #define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL) #endif /* CONFIG_64BIT */
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> --- Changes since V1: This is a modified version of the patch posted by Alexandre Ghiti <alexghiti@rivosinc.com> [1]. That version moved the start of the liner mapping by 4GiB, but was subsequently found to trigger a problem in the KASAN code [2]. By moving the start address by 8GiB alignment requiremenents are maintained. [1] https://lore.kernel.org/linux-riscv/20240514133614.87813-1-alexghiti@rivosinc.com/ [2] https://lore.kernel.org/linux-riscv/4011b34a-1b86-42c7-aaf6-3bd297149f06@ghiti.fr/ --- Documentation/arch/riscv/vm-layout.rst | 11 ++++++----- arch/riscv/include/asm/page.h | 2 +- 2 files changed, 7 insertions(+), 6 deletions(-)