On 32-bit platforms, these convert from kernel virtual addresses
to real (physical addresses), like tophys/tovirt but they use
the same register for the source and destination. On 64-bit
platforms, they do nothing because the hardware ignores the top
two bits of the address in real mode.
These new macros are used in fpu.S now.
Signed-off-by: Paul Mackerras <paulus@samba.org>
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