• Greentime Hu's avatar
    nds32: Exception handling · 2923f5ea
    Greentime Hu authored
    This patch includes the exception/interrupt entries, pt_reg structure and
    related accessors.
    
    /* Unaligned accessing handling*/
    Andes processors cannot load/store information which is not naturally
    aligned on the bus, i.e., loading a 4 byte data whose start address must
    be divisible by 4. If unaligned data accessing is happened, data
    unaligned exception will be triggered and user will get SIGSEGV or
    kernel oops according to the unaligned address. In order to make user be
    able to load/store data from an unaligned address, software load/store
    emulation is implemented in arch/nds32/mm/alignment.c to address data
    unaligned exception.
    
    Unaligned accessing handling is disabled by default because it is not a
    normal case. User can enable this feature by following steps.
    
    A. Compile time:
        1. Enable kernel config CONFIG_ALIGNMENT_TRAP
    B. Run time:
        1. Enter /proc/sys/nds32/unaligned_acess folder
        2. Write 1 to file enable_mode to enable unaligned accessing
           handling. User can disable it by writing 0 to this file.
        3. Write 1 to file debug to show which unaligned address is under
           processing. User can disable it by writing 0 to this file.
    
    However, unaligned accessing handler cannot work if this unaligned
    address is not accessible such as protection violation. On this
    condition, the default behaviors for addressing data unaligned exception
    still happen
    Signed-off-by: default avatarVincent Chen <vincentc@andestech.com>
    Signed-off-by: default avatarGreentime Hu <greentime@andestech.com>
    Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
    2923f5ea
ex-exit.S 3.68 KB