sh: add kexec jump support

Add kexec jump support to the SuperH architecture.

Similar to the x86 implementation, with the following
exceptions:

- Instead of separating the assembly code flow into
two parts for regular kexec and kexec jump we use a
single code path. In the assembly snippet regular
kexec is just kexec jump that never comes back.

- Instead of using a swap page when moving data between
pages the page copy assembly routine has been modified
to exchange the data between the pages using registers.

- We walk the page list twice in machine_kexec() to
do and undo physical to virtual address conversion.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 6c56495fd158..8d50d527c595 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -559,6 +559,13 @@ config CRASH_DUMP
 
           For more details see Documentation/kdump/kdump.txt
 
+config KEXEC_JUMP
+        bool "kexec jump (EXPERIMENTAL)"
+        depends on SUPERH32 && KEXEC && HIBERNATION && EXPERIMENTAL
+        help
+          Jump between original kernel and kexeced kernel and invoke
+          code via KEXEC
+
 config SECCOMP
         bool "Enable seccomp to safely compute untrusted bytecode"
         depends on PROC_FS