powerpc: Merge enough to start building in arch/powerpc.

This creates the directory structure under arch/powerpc and a bunch
of Kconfig files.  It does a first-cut merge of arch/powerpc/mm,
arch/powerpc/lib and arch/powerpc/platforms/powermac.  This is enough
to build a 32-bit powermac kernel with ARCH=powerpc.

For now we are getting some unmerged files from arch/ppc/kernel and
arch/ppc/syslib, or arch/ppc64/kernel.  This makes some minor changes
to files in those directories and files outside arch/powerpc.

The boot directory is still not merged.  That's going to be interesting.

Signed-off-by: Paul Mackerras <paulus@samba.org>

include/asm-powerpc/kdebug.h

@@ -0,0 +1,42 @@
+#ifndef _POWERPC_KDEBUG_H
+#define _POWERPC_KDEBUG_H 1
+
+/* nearly identical to x86_64/i386 code */
+
+#include <linux/notifier.h>
+
+struct pt_regs;
+
+struct die_args {
+	struct pt_regs *regs;
+	const char *str;
+	long err;
+	int trapnr;
+	int signr;
+};
+
+/*
+   Note - you should never unregister because that can race with NMIs.
+   If you really want to do it first unregister - then synchronize_sched -
+   then free.
+ */
+int register_die_notifier(struct notifier_block *nb);
+extern struct notifier_block *powerpc_die_chain;
+
+/* Grossly misnamed. */
+enum die_val {
+	DIE_OOPS = 1,
+	DIE_IABR_MATCH,
+	DIE_DABR_MATCH,
+	DIE_BPT,
+	DIE_SSTEP,
+	DIE_PAGE_FAULT,
+};
+
+static inline int notify_die(enum die_val val,char *str,struct pt_regs *regs,long err,int trap, int sig)
+{
+	struct die_args args = { .regs=regs, .str=str, .err=err, .trapnr=trap,.signr=sig };
+	return notifier_call_chain(&powerpc_die_chain, val, &args);
+}
+
+#endif