powerpc: Move ppc64 boot wrapper code over to arch/powerpc

This also extends the code to handle 32-bit ELF vmlinux files as well
as 64-bit ones.  This is sufficient for booting on new-world 32-bit
powermacs (i.e. all recent machines).

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

arch/powerpc/boot/crt0.S

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) Paul Mackerras 1997.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * NOTE: this code runs in 32 bit mode and is packaged as ELF32.
+ */
+
+#include "ppc_asm.h"
+
+	.text
+	.globl	_zimage_start
+_zimage_start:
+	bl	reloc_offset
+
+reloc_offset:
+	mflr	r0
+	lis	r9,reloc_offset@ha
+	addi	r9,r9,reloc_offset@l
+	subf.	r0,r9,r0
+	beq	clear_caches
+
+reloc_got2:
+	lis	r9,__got2_start@ha
+	addi	r9,r9,__got2_start@l
+	lis	r8,__got2_end@ha
+	addi	r8,r8,__got2_end@l
+	subf.	r8,r9,r8
+	beq	clear_caches
+	srwi.	r8,r8,2
+	mtctr	r8
+	add	r9,r0,r9
+reloc_got2_loop:
+	lwz	r8,0(r9)
+	add	r8,r8,r0
+	stw	r8,0(r9)
+	addi	r9,r9,4
+	bdnz	reloc_got2_loop
+
+clear_caches:
+	lis	r9,_start@h
+	add	r9,r0,r9
+	lis	r8,_etext@ha
+	addi	r8,r8,_etext@l
+	add	r8,r0,r8
+1:	dcbf	r0,r9
+	icbi	r0,r9
+	addi	r9,r9,0x20
+	cmplwi	0,r9,8
+	blt	1b
+	sync
+	isync
+
+	mr	r6,r1
+	b	start
+