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    riscv: Add KASAN support · 8ad8b727
    Nick Hu authored
    
    
    This patch ports the feature Kernel Address SANitizer (KASAN).
    
    Note: The start address of shadow memory is at the beginning of kernel
    space, which is 2^64 - (2^39 / 2) in SV39. The size of the kernel space is
    2^38 bytes so the size of shadow memory should be 2^38 / 8. Thus, the
    shadow memory would not overlap with the fixmap area.
    
    There are currently two limitations in this port,
    
    1. RV64 only: KASAN need large address space for extra shadow memory
    region.
    
    2. KASAN can't debug the modules since the modules are allocated in VMALLOC
    area. We mapped the shadow memory, which corresponding to VMALLOC area, to
    the kasan_early_shadow_page because we don't have enough physical space for
    all the shadow memory corresponding to VMALLOC area.
    
    Signed-off-by: default avatarNick Hu <nickhu@andestech.com>
    Reported-by: default avatarGreentime Hu <green.hu@gmail.com>
    Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
    8ad8b727