• Michael Neuling's avatar
    powerpc: Add relocation on exception vector handlers · c1fb6816
    Michael Neuling authored
    POWER8/v2.07 allows exceptions to be taken with the MMU still on.
    
    A new set of exception vectors is added at 0xc000_0000_0000_4xxx.  When the HW
    takes us here, MSR IR/DR will be set already and we no longer need a costly
    RFID to turn the MMU back on again.
    
    The original 0x0 based exception vectors remain for when the HW can't leave the
    MMU on.  Examples of this are when we can't trust the current MMU mappings,
    like when we are changing from guest to hypervisor (HV 0 -> 1) or when the MMU
    was off already.  In these cases the HW will take us to the original 0x0 based
    exception vectors with the MMU off as before.
    
    This uses the new macros added previously too implement these new execption
    vectors at 0xc000_0000_0000_4xxx.  We exit these exception vectors using
    mflr/blr (rather than mtspr SSR0/RFID), since we don't need the costly MMU
    switch anymore.
    
    This moves the __end_interrupts marker down past these new 0x4000 vectors since
    they will need to be copied down to 0x0 when the kernel is not at 0x0.
    Signed-off-by: default avatarMatt Evans <matt@ozlabs.org>
    Signed-off-by: default avatarMichael Neuling <mikey@neuling.org>
    Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
    c1fb6816
head_64.S 19.9 KB