• Zong Li's avatar
    riscv: introduce interfaces to patch kernel code · 043cb41a
    Zong Li authored
    On strict kernel memory permission, we couldn't patch code without
    writable permission. Preserve two holes in fixmap area, so we can map
    the kernel code temporarily to fixmap area, then patch the instructions.
    
    We need two pages here because we support the compressed instruction, so
    the instruction might be align to 2 bytes. When patching the 32-bit
    length instruction which is 2 bytes alignment, it will across two pages.
    
    Introduce two interfaces to patch kernel code:
    riscv_patch_text_nosync:
     - patch code without synchronization, it's caller's responsibility to
       synchronize all CPUs if needed.
    riscv_patch_text:
     - patch code and always synchronize with stop_machine()
    Signed-off-by: default avatarZong Li <zong.li@sifive.com>
    Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
    043cb41a
patch.c 2.45 KB