powerpc/47x: Kernel support for KEXEC
This patch adds support for creating 1:1 mapping for the PPC_47x during a KEXEC. The implementation is similar to that of the PPC440x which is described here : http://patchwork.ozlabs.org/patch/104323/ PPC_47x MMU : The 47x uses Unified TLB 1024 entries, with 4-way associative mapping (4 x 256 entries). The index to be used is calculated by the MMU by hashing the PID, EPN and TS. The software can choose to specify the way by setting bit 0(enable way select) and the way in bits 1-2 in the TLB Word 0. Implementation: The patch erases all the UTLB entries which includes the tlb covering the mapping for our code. The shadow TLB caches the mapping for the running code which helps us to continue the execution until we do isync/rfi. We then create a tmp mapping for the current code in the other address space (TS) and switch to it. Then we create a 1:1 mapping(EPN=RPN) for 0-2GiB in the original address space and switch to the new mapping. TODO: Add SMP support. Signed-off-by: NSuzuki K. Poulose <suzuki@in.ibm.com> Signed-off-by: NJosh Boyer <jwboyer@gmail.com>
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