• Heiko Carstens's avatar
    s390: add proper __ro_after_init support · d07a980c
    Heiko Carstens authored
    
    
    On s390 __ro_after_init is currently mapped to __read_mostly which
    means that data marked as __ro_after_init will not be protected.
    
    Reason for this is that the common code __ro_after_init implementation
    is x86 centric: the ro_after_init data section was added to rodata,
    since x86 enables write protection to kernel text and rodata very
    late. On s390 we have write protection for these sections enabled with
    the initial page tables. So adding the ro_after_init data section to
    rodata does not work on s390.
    
    In order to make __ro_after_init work properly on s390 move the
    ro_after_init data, right behind rodata. Unlike the rodata section it
    will be marked read-only later after all init calls happened.
    
    This s390 specific implementation adds new __start_ro_after_init and
    __end_ro_after_init labels. Everything in between will be marked
    read-only after the init calls happened. In addition to the
    __ro_after_init data move also the exception table there, since from a
    practical point of view it fits the __ro_after_init requirements.
    Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
    Reviewed-by: default avatarKees Cook <keescook@chromium.org>
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    d07a980c