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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 the 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. The below macros are copies of the macros used at the 0x0 offset but modified to handle the MMU being on. In these macros we use the link register to jump to the secondary handlers rather than using RFID (RFID was also use to turn on the MMU). Signed-off-by: Matt Evans <matt@ozlabs.org> Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> |
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uapi/asm |