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: Suzuki K. Poulose <suzuki@in.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@gmail.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index feab3bad6d0f..e588bac91059 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -353,7 +353,7 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
 
 config KEXEC
         bool "kexec system call (EXPERIMENTAL)"
-        depends on (PPC_BOOK3S || FSL_BOOKE || (44x && !SMP && !PPC_47x)) && EXPERIMENTAL
+        depends on (PPC_BOOK3S || FSL_BOOKE || (44x && !SMP)) && EXPERIMENTAL
         help
           kexec is a system call that implements the ability to shutdown your
           current kernel, and to start another kernel.  It is like a reboot