• Palmer Dabbelt's avatar
    RISC-V: Introduce sv48 support without relocatable kernel · 0c34e79e
    Palmer Dabbelt authored
    This patchset allows to have a single kernel for sv39 and sv48 without
    being relocatable.
    
    The idea comes from Arnd Bergmann who suggested to do the same as x86,
    that is mapping the kernel to the end of the address space, which allows
    the kernel to be linked at the same address for both sv39 and sv48 and
    then does not require to be relocated at runtime.
    
    This implements sv48 support at runtime. The kernel will try to boot
    with 4-level page table and will fallback to 3-level if the HW does not
    support it. Folding the 4th level into a 3-level page table has almost
    no cost at runtime.
    
    Note that kasan region had to be moved to the end of the address space
    since its location must be known at compile-time and then be valid for
    both sv39 and sv48 (and sv57 that is coming).
    
    * riscv-sv48-v3:
      riscv: Explicit comment about user virtual address space size
      riscv: Use pgtable_l4_enabled to output mmu_type in cpuinfo
      riscv: Implement sv48 support
      asm-generic: Prepare for riscv use of pud_alloc_one and pud_free
      riscv: Allow to dynamically define VA_BITS
      riscv: Introduce functions to switch pt_ops
      riscv: Split early kasan mapping to prepare sv48 introduction
      riscv: Move KASAN mapping next to the kernel mapping
      riscv: Get rid of MAXPHYSMEM configs
    Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
    0c34e79e
efi-stub.c 10.8 KB