xref: /openbmc/linux/arch/powerpc/kernel/head_8xx.S (revision ef2b56df)
1/*
2 *  PowerPC version
3 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
4 *  Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
5 *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
6 *  Low-level exception handlers and MMU support
7 *  rewritten by Paul Mackerras.
8 *    Copyright (C) 1996 Paul Mackerras.
9 *  MPC8xx modifications by Dan Malek
10 *    Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
11 *
12 *  This file contains low-level support and setup for PowerPC 8xx
13 *  embedded processors, including trap and interrupt dispatch.
14 *
15 *  This program is free software; you can redistribute it and/or
16 *  modify it under the terms of the GNU General Public License
17 *  as published by the Free Software Foundation; either version
18 *  2 of the License, or (at your option) any later version.
19 *
20 */
21
22#include <linux/init.h>
23#include <asm/processor.h>
24#include <asm/page.h>
25#include <asm/mmu.h>
26#include <asm/cache.h>
27#include <asm/pgtable.h>
28#include <asm/cputable.h>
29#include <asm/thread_info.h>
30#include <asm/ppc_asm.h>
31#include <asm/asm-offsets.h>
32#include <asm/ptrace.h>
33#include <asm/fixmap.h>
34#include <asm/export.h>
35
36/* Macro to make the code more readable. */
37#ifdef CONFIG_8xx_CPU6
38#define SPRN_MI_TWC_ADDR	0x2b80
39#define SPRN_MI_RPN_ADDR	0x2d80
40#define SPRN_MD_TWC_ADDR	0x3b80
41#define SPRN_MD_RPN_ADDR	0x3d80
42
43#define MTSPR_CPU6(spr, reg, treg)	\
44	li	treg, spr##_ADDR;	\
45	stw	treg, 12(r0);		\
46	lwz	treg, 12(r0);		\
47	mtspr	spr, reg
48#else
49#define MTSPR_CPU6(spr, reg, treg)	\
50	mtspr	spr, reg
51#endif
52
53/* Macro to test if an address is a kernel address */
54#if CONFIG_TASK_SIZE <= 0x80000000 && CONFIG_PAGE_OFFSET >= 0x80000000
55#define IS_KERNEL(tmp, addr)		\
56	andis.	tmp, addr, 0x8000	/* Address >= 0x80000000 */
57#define BRANCH_UNLESS_KERNEL(label)	beq	label
58#else
59#define IS_KERNEL(tmp, addr)		\
60	rlwinm	tmp, addr, 16, 16, 31;	\
61	cmpli	cr0, tmp, PAGE_OFFSET >> 16
62#define BRANCH_UNLESS_KERNEL(label)	blt	label
63#endif
64
65
66/*
67 * Value for the bits that have fixed value in RPN entries.
68 * Also used for tagging DAR for DTLBerror.
69 */
70#ifdef CONFIG_PPC_16K_PAGES
71#define RPN_PATTERN	(0x00f0 | MD_SPS16K)
72#else
73#define RPN_PATTERN	0x00f0
74#endif
75
76#define PAGE_SHIFT_512K		19
77#define PAGE_SHIFT_8M		23
78
79	__HEAD
80_ENTRY(_stext);
81_ENTRY(_start);
82
83/* MPC8xx
84 * This port was done on an MBX board with an 860.  Right now I only
85 * support an ELF compressed (zImage) boot from EPPC-Bug because the
86 * code there loads up some registers before calling us:
87 *   r3: ptr to board info data
88 *   r4: initrd_start or if no initrd then 0
89 *   r5: initrd_end - unused if r4 is 0
90 *   r6: Start of command line string
91 *   r7: End of command line string
92 *
93 * I decided to use conditional compilation instead of checking PVR and
94 * adding more processor specific branches around code I don't need.
95 * Since this is an embedded processor, I also appreciate any memory
96 * savings I can get.
97 *
98 * The MPC8xx does not have any BATs, but it supports large page sizes.
99 * We first initialize the MMU to support 8M byte pages, then load one
100 * entry into each of the instruction and data TLBs to map the first
101 * 8M 1:1.  I also mapped an additional I/O space 1:1 so we can get to
102 * the "internal" processor registers before MMU_init is called.
103 *
104 *	-- Dan
105 */
106	.globl	__start
107__start:
108	mr	r31,r3			/* save device tree ptr */
109
110	/* We have to turn on the MMU right away so we get cache modes
111	 * set correctly.
112	 */
113	bl	initial_mmu
114
115/* We now have the lower 8 Meg mapped into TLB entries, and the caches
116 * ready to work.
117 */
118
119turn_on_mmu:
120	mfmsr	r0
121	ori	r0,r0,MSR_DR|MSR_IR
122	mtspr	SPRN_SRR1,r0
123	lis	r0,start_here@h
124	ori	r0,r0,start_here@l
125	mtspr	SPRN_SRR0,r0
126	SYNC
127	rfi				/* enables MMU */
128
129/*
130 * Exception entry code.  This code runs with address translation
131 * turned off, i.e. using physical addresses.
132 * We assume sprg3 has the physical address of the current
133 * task's thread_struct.
134 */
135#define EXCEPTION_PROLOG	\
136	EXCEPTION_PROLOG_0;	\
137	mfcr	r10;		\
138	EXCEPTION_PROLOG_1;	\
139	EXCEPTION_PROLOG_2
140
141#define EXCEPTION_PROLOG_0	\
142	mtspr	SPRN_SPRG_SCRATCH0,r10;	\
143	mtspr	SPRN_SPRG_SCRATCH1,r11
144
145#define EXCEPTION_PROLOG_1	\
146	mfspr	r11,SPRN_SRR1;		/* check whether user or kernel */ \
147	andi.	r11,r11,MSR_PR;	\
148	tophys(r11,r1);			/* use tophys(r1) if kernel */ \
149	beq	1f;		\
150	mfspr	r11,SPRN_SPRG_THREAD;	\
151	lwz	r11,THREAD_INFO-THREAD(r11);	\
152	addi	r11,r11,THREAD_SIZE;	\
153	tophys(r11,r11);	\
1541:	subi	r11,r11,INT_FRAME_SIZE	/* alloc exc. frame */
155
156
157#define EXCEPTION_PROLOG_2	\
158	stw	r10,_CCR(r11);		/* save registers */ \
159	stw	r12,GPR12(r11);	\
160	stw	r9,GPR9(r11);	\
161	mfspr	r10,SPRN_SPRG_SCRATCH0;	\
162	stw	r10,GPR10(r11);	\
163	mfspr	r12,SPRN_SPRG_SCRATCH1;	\
164	stw	r12,GPR11(r11);	\
165	mflr	r10;		\
166	stw	r10,_LINK(r11);	\
167	mfspr	r12,SPRN_SRR0;	\
168	mfspr	r9,SPRN_SRR1;	\
169	stw	r1,GPR1(r11);	\
170	stw	r1,0(r11);	\
171	tovirt(r1,r11);			/* set new kernel sp */	\
172	li	r10,MSR_KERNEL & ~(MSR_IR|MSR_DR); /* can take exceptions */ \
173	MTMSRD(r10);			/* (except for mach check in rtas) */ \
174	stw	r0,GPR0(r11);	\
175	SAVE_4GPRS(3, r11);	\
176	SAVE_2GPRS(7, r11)
177
178/*
179 * Exception exit code.
180 */
181#define EXCEPTION_EPILOG_0	\
182	mfspr	r10,SPRN_SPRG_SCRATCH0;	\
183	mfspr	r11,SPRN_SPRG_SCRATCH1
184
185/*
186 * Note: code which follows this uses cr0.eq (set if from kernel),
187 * r11, r12 (SRR0), and r9 (SRR1).
188 *
189 * Note2: once we have set r1 we are in a position to take exceptions
190 * again, and we could thus set MSR:RI at that point.
191 */
192
193/*
194 * Exception vectors.
195 */
196#define EXCEPTION(n, label, hdlr, xfer)		\
197	. = n;					\
198label:						\
199	EXCEPTION_PROLOG;			\
200	addi	r3,r1,STACK_FRAME_OVERHEAD;	\
201	xfer(n, hdlr)
202
203#define EXC_XFER_TEMPLATE(n, hdlr, trap, copyee, tfer, ret)	\
204	li	r10,trap;					\
205	stw	r10,_TRAP(r11);					\
206	li	r10,MSR_KERNEL;					\
207	copyee(r10, r9);					\
208	bl	tfer;						\
209i##n:								\
210	.long	hdlr;						\
211	.long	ret
212
213#define COPY_EE(d, s)		rlwimi d,s,0,16,16
214#define NOCOPY(d, s)
215
216#define EXC_XFER_STD(n, hdlr)		\
217	EXC_XFER_TEMPLATE(n, hdlr, n, NOCOPY, transfer_to_handler_full,	\
218			  ret_from_except_full)
219
220#define EXC_XFER_LITE(n, hdlr)		\
221	EXC_XFER_TEMPLATE(n, hdlr, n+1, NOCOPY, transfer_to_handler, \
222			  ret_from_except)
223
224#define EXC_XFER_EE(n, hdlr)		\
225	EXC_XFER_TEMPLATE(n, hdlr, n, COPY_EE, transfer_to_handler_full, \
226			  ret_from_except_full)
227
228#define EXC_XFER_EE_LITE(n, hdlr)	\
229	EXC_XFER_TEMPLATE(n, hdlr, n+1, COPY_EE, transfer_to_handler, \
230			  ret_from_except)
231
232/* System reset */
233	EXCEPTION(0x100, Reset, system_reset_exception, EXC_XFER_STD)
234
235/* Machine check */
236	. = 0x200
237MachineCheck:
238	EXCEPTION_PROLOG
239	mfspr r4,SPRN_DAR
240	stw r4,_DAR(r11)
241	li r5,RPN_PATTERN
242	mtspr SPRN_DAR,r5	/* Tag DAR, to be used in DTLB Error */
243	mfspr r5,SPRN_DSISR
244	stw r5,_DSISR(r11)
245	addi r3,r1,STACK_FRAME_OVERHEAD
246	EXC_XFER_STD(0x200, machine_check_exception)
247
248/* Data access exception.
249 * This is "never generated" by the MPC8xx.
250 */
251	. = 0x300
252DataAccess:
253
254/* Instruction access exception.
255 * This is "never generated" by the MPC8xx.
256 */
257	. = 0x400
258InstructionAccess:
259
260/* External interrupt */
261	EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
262
263/* Alignment exception */
264	. = 0x600
265Alignment:
266	EXCEPTION_PROLOG
267	mfspr	r4,SPRN_DAR
268	stw	r4,_DAR(r11)
269	li	r5,RPN_PATTERN
270	mtspr	SPRN_DAR,r5	/* Tag DAR, to be used in DTLB Error */
271	mfspr	r5,SPRN_DSISR
272	stw	r5,_DSISR(r11)
273	addi	r3,r1,STACK_FRAME_OVERHEAD
274	EXC_XFER_EE(0x600, alignment_exception)
275
276/* Program check exception */
277	EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)
278
279/* No FPU on MPC8xx.  This exception is not supposed to happen.
280*/
281	EXCEPTION(0x800, FPUnavailable, unknown_exception, EXC_XFER_STD)
282
283/* Decrementer */
284	EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE)
285
286	EXCEPTION(0xa00, Trap_0a, unknown_exception, EXC_XFER_EE)
287	EXCEPTION(0xb00, Trap_0b, unknown_exception, EXC_XFER_EE)
288
289/* System call */
290	. = 0xc00
291SystemCall:
292	EXCEPTION_PROLOG
293	EXC_XFER_EE_LITE(0xc00, DoSyscall)
294
295/* Single step - not used on 601 */
296	EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)
297	EXCEPTION(0xe00, Trap_0e, unknown_exception, EXC_XFER_EE)
298	EXCEPTION(0xf00, Trap_0f, unknown_exception, EXC_XFER_EE)
299
300/* On the MPC8xx, this is a software emulation interrupt.  It occurs
301 * for all unimplemented and illegal instructions.
302 */
303	EXCEPTION(0x1000, SoftEmu, SoftwareEmulation, EXC_XFER_STD)
304
305	. = 0x1100
306/*
307 * For the MPC8xx, this is a software tablewalk to load the instruction
308 * TLB.  The task switch loads the M_TW register with the pointer to the first
309 * level table.
310 * If we discover there is no second level table (value is zero) or if there
311 * is an invalid pte, we load that into the TLB, which causes another fault
312 * into the TLB Error interrupt where we can handle such problems.
313 * We have to use the MD_xxx registers for the tablewalk because the
314 * equivalent MI_xxx registers only perform the attribute functions.
315 */
316
317#ifdef CONFIG_8xx_CPU15
318#define INVALIDATE_ADJACENT_PAGES_CPU15(tmp, addr)	\
319	addi	tmp, addr, PAGE_SIZE;	\
320	tlbie	tmp;			\
321	addi	tmp, addr, -PAGE_SIZE;	\
322	tlbie	tmp
323#else
324#define INVALIDATE_ADJACENT_PAGES_CPU15(tmp, addr)
325#endif
326
327InstructionTLBMiss:
328#if defined(CONFIG_8xx_CPU6) || defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC) || defined (CONFIG_HUGETLB_PAGE)
329	mtspr	SPRN_SPRG_SCRATCH2, r3
330#endif
331	EXCEPTION_PROLOG_0
332#ifdef CONFIG_PPC_8xx_PERF_EVENT
333	lis	r10, (itlb_miss_counter - PAGE_OFFSET)@ha
334	lwz	r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)
335	addi	r11, r11, 1
336	stw	r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)
337#endif
338
339	/* If we are faulting a kernel address, we have to use the
340	 * kernel page tables.
341	 */
342	mfspr	r10, SPRN_SRR0	/* Get effective address of fault */
343	INVALIDATE_ADJACENT_PAGES_CPU15(r11, r10)
344	/* Only modules will cause ITLB Misses as we always
345	 * pin the first 8MB of kernel memory */
346#if defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC) || defined (CONFIG_HUGETLB_PAGE)
347	mfcr	r3
348#endif
349#if defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC)
350	IS_KERNEL(r11, r10)
351#endif
352	mfspr	r11, SPRN_M_TW	/* Get level 1 table */
353#if defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC)
354	BRANCH_UNLESS_KERNEL(3f)
355	lis	r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3563:
357#endif
358	/* Insert level 1 index */
359	rlwimi	r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
360	lwz	r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11)	/* Get the level 1 entry */
361
362	/* Extract level 2 index */
363	rlwinm	r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
364#ifdef CONFIG_HUGETLB_PAGE
365	mtcr	r11
366	bt-	28, 10f		/* bit 28 = Large page (8M) */
367	bt-	29, 20f		/* bit 29 = Large page (8M or 512k) */
368#endif
369	rlwimi	r10, r11, 0, 0, 32 - PAGE_SHIFT - 1	/* Add level 2 base */
370	lwz	r10, 0(r10)	/* Get the pte */
3714:
372#if defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC) || defined (CONFIG_HUGETLB_PAGE)
373	mtcr	r3
374#endif
375	/* Insert the APG into the TWC from the Linux PTE. */
376	rlwimi	r11, r10, 0, 25, 26
377	/* Load the MI_TWC with the attributes for this "segment." */
378	MTSPR_CPU6(SPRN_MI_TWC, r11, r3)	/* Set segment attributes */
379
380#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
381	rlwimi	r10, r11, 1, MI_SPS16K
382#endif
383#ifdef CONFIG_SWAP
384	rlwinm	r11, r10, 32-5, _PAGE_PRESENT
385	and	r11, r11, r10
386	rlwimi	r10, r11, 0, _PAGE_PRESENT
387#endif
388	li	r11, RPN_PATTERN
389	/* The Linux PTE won't go exactly into the MMU TLB.
390	 * Software indicator bits 20-23 and 28 must be clear.
391	 * Software indicator bits 24, 25, 26, and 27 must be
392	 * set.  All other Linux PTE bits control the behavior
393	 * of the MMU.
394	 */
395#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
396	rlwimi	r10, r11, 0, 0x0ff0	/* Set 24-27, clear 20-23 */
397#else
398	rlwimi	r10, r11, 0, 0x0ff8	/* Set 24-27, clear 20-23,28 */
399#endif
400	MTSPR_CPU6(SPRN_MI_RPN, r10, r3)	/* Update TLB entry */
401
402	/* Restore registers */
403#if defined(CONFIG_8xx_CPU6) || defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC) || defined (CONFIG_HUGETLB_PAGE)
404	mfspr	r3, SPRN_SPRG_SCRATCH2
405#endif
406	EXCEPTION_EPILOG_0
407	rfi
408
409#ifdef CONFIG_HUGETLB_PAGE
41010:	/* 8M pages */
411#ifdef CONFIG_PPC_16K_PAGES
412	/* Extract level 2 index */
413	rlwinm	r10, r10, 32 - (PAGE_SHIFT_8M - PAGE_SHIFT), 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1), 29
414	/* Add level 2 base */
415	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1) - 1
416#else
417	/* Level 2 base */
418	rlwinm	r10, r11, 0, ~HUGEPD_SHIFT_MASK
419#endif
420	lwz	r10, 0(r10)	/* Get the pte */
421	rlwinm	r11, r11, 0, 0xf
422	b	4b
423
42420:	/* 512k pages */
425	/* Extract level 2 index */
426	rlwinm	r10, r10, 32 - (PAGE_SHIFT_512K - PAGE_SHIFT), 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1), 29
427	/* Add level 2 base */
428	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
429	lwz	r10, 0(r10)	/* Get the pte */
430	rlwinm	r11, r11, 0, 0xf
431	b	4b
432#endif
433
434	. = 0x1200
435DataStoreTLBMiss:
436	mtspr	SPRN_SPRG_SCRATCH2, r3
437	EXCEPTION_PROLOG_0
438#ifdef CONFIG_PPC_8xx_PERF_EVENT
439	lis	r10, (dtlb_miss_counter - PAGE_OFFSET)@ha
440	lwz	r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)
441	addi	r11, r11, 1
442	stw	r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)
443#endif
444	mfcr	r3
445
446	/* If we are faulting a kernel address, we have to use the
447	 * kernel page tables.
448	 */
449	mfspr	r10, SPRN_MD_EPN
450	rlwinm	r10, r10, 16, 0xfff8
451	cmpli	cr0, r10, PAGE_OFFSET@h
452	mfspr	r11, SPRN_M_TW	/* Get level 1 table */
453	blt+	3f
454#ifndef CONFIG_PIN_TLB_IMMR
455	cmpli	cr0, r10, VIRT_IMMR_BASE@h
456#endif
457_ENTRY(DTLBMiss_cmp)
458	cmpli	cr7, r10, (PAGE_OFFSET + 0x1800000)@h
459	lis	r11, (swapper_pg_dir-PAGE_OFFSET)@ha
460#ifndef CONFIG_PIN_TLB_IMMR
461_ENTRY(DTLBMiss_jmp)
462	beq-	DTLBMissIMMR
463#endif
464	blt	cr7, DTLBMissLinear
4653:
466	mfspr	r10, SPRN_MD_EPN
467
468	/* Insert level 1 index */
469	rlwimi	r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
470	lwz	r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11)	/* Get the level 1 entry */
471
472	/* We have a pte table, so load fetch the pte from the table.
473	 */
474	/* Extract level 2 index */
475	rlwinm	r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
476#ifdef CONFIG_HUGETLB_PAGE
477	mtcr	r11
478	bt-	28, 10f		/* bit 28 = Large page (8M) */
479	bt-	29, 20f		/* bit 29 = Large page (8M or 512k) */
480#endif
481	rlwimi	r10, r11, 0, 0, 32 - PAGE_SHIFT - 1	/* Add level 2 base */
482	lwz	r10, 0(r10)	/* Get the pte */
4834:
484	mtcr	r3
485
486	/* Insert the Guarded flag and APG into the TWC from the Linux PTE.
487	 * It is bit 26-27 of both the Linux PTE and the TWC (at least
488	 * I got that right :-).  It will be better when we can put
489	 * this into the Linux pgd/pmd and load it in the operation
490	 * above.
491	 */
492	rlwimi	r11, r10, 0, 26, 27
493	/* Insert the WriteThru flag into the TWC from the Linux PTE.
494	 * It is bit 25 in the Linux PTE and bit 30 in the TWC
495	 */
496	rlwimi	r11, r10, 32-5, 30, 30
497	MTSPR_CPU6(SPRN_MD_TWC, r11, r3)
498
499	/* In 4k pages mode, SPS (bit 28) in RPN must match PS[1] (bit 29)
500	 * In 16k pages mode, SPS is always 1 */
501#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
502	rlwimi	r10, r11, 1, MD_SPS16K
503#endif
504	/* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
505	 * We also need to know if the insn is a load/store, so:
506	 * Clear _PAGE_PRESENT and load that which will
507	 * trap into DTLB Error with store bit set accordinly.
508	 */
509	/* PRESENT=0x1, ACCESSED=0x20
510	 * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5));
511	 * r10 = (r10 & ~PRESENT) | r11;
512	 */
513#ifdef CONFIG_SWAP
514	rlwinm	r11, r10, 32-5, _PAGE_PRESENT
515	and	r11, r11, r10
516	rlwimi	r10, r11, 0, _PAGE_PRESENT
517#endif
518	/* The Linux PTE won't go exactly into the MMU TLB.
519	 * Software indicator bits 22 and 28 must be clear.
520	 * Software indicator bits 24, 25, 26, and 27 must be
521	 * set.  All other Linux PTE bits control the behavior
522	 * of the MMU.
523	 */
524	li	r11, RPN_PATTERN
525#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
526	rlwimi	r10, r11, 0, 24, 27	/* Set 24-27 */
527#else
528	rlwimi	r10, r11, 0, 24, 28	/* Set 24-27, clear 28 */
529#endif
530	rlwimi	r10, r11, 0, 20, 20	/* clear 20 */
531	MTSPR_CPU6(SPRN_MD_RPN, r10, r3)	/* Update TLB entry */
532
533	/* Restore registers */
534	mfspr	r3, SPRN_SPRG_SCRATCH2
535	mtspr	SPRN_DAR, r11	/* Tag DAR */
536	EXCEPTION_EPILOG_0
537	rfi
538
539#ifdef CONFIG_HUGETLB_PAGE
54010:	/* 8M pages */
541	/* Extract level 2 index */
542#ifdef CONFIG_PPC_16K_PAGES
543	rlwinm	r10, r10, 32 - (PAGE_SHIFT_8M - PAGE_SHIFT), 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1), 29
544	/* Add level 2 base */
545	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1) - 1
546#else
547	/* Level 2 base */
548	rlwinm	r10, r11, 0, ~HUGEPD_SHIFT_MASK
549#endif
550	lwz	r10, 0(r10)	/* Get the pte */
551	rlwinm	r11, r11, 0, 0xf
552	b	4b
553
55420:	/* 512k pages */
555	/* Extract level 2 index */
556	rlwinm	r10, r10, 32 - (PAGE_SHIFT_512K - PAGE_SHIFT), 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1), 29
557	/* Add level 2 base */
558	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
559	lwz	r10, 0(r10)	/* Get the pte */
560	rlwinm	r11, r11, 0, 0xf
561	b	4b
562#endif
563
564/* This is an instruction TLB error on the MPC8xx.  This could be due
565 * to many reasons, such as executing guarded memory or illegal instruction
566 * addresses.  There is nothing to do but handle a big time error fault.
567 */
568	. = 0x1300
569InstructionTLBError:
570	EXCEPTION_PROLOG
571	mr	r4,r12
572	mr	r5,r9
573	andis.	r10,r5,0x4000
574	beq+	1f
575	tlbie	r4
576itlbie:
577	/* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
5781:	EXC_XFER_LITE(0x400, handle_page_fault)
579
580/* This is the data TLB error on the MPC8xx.  This could be due to
581 * many reasons, including a dirty update to a pte.  We bail out to
582 * a higher level function that can handle it.
583 */
584	. = 0x1400
585DataTLBError:
586	EXCEPTION_PROLOG_0
587	mfcr	r10
588
589	mfspr	r11, SPRN_DAR
590	cmpwi	cr0, r11, RPN_PATTERN
591	beq-	FixupDAR	/* must be a buggy dcbX, icbi insn. */
592DARFixed:/* Return from dcbx instruction bug workaround */
593	EXCEPTION_PROLOG_1
594	EXCEPTION_PROLOG_2
595	mfspr	r5,SPRN_DSISR
596	stw	r5,_DSISR(r11)
597	mfspr	r4,SPRN_DAR
598	andis.	r10,r5,0x4000
599	beq+	1f
600	tlbie	r4
601dtlbie:
6021:	li	r10,RPN_PATTERN
603	mtspr	SPRN_DAR,r10	/* Tag DAR, to be used in DTLB Error */
604	/* 0x300 is DataAccess exception, needed by bad_page_fault() */
605	EXC_XFER_LITE(0x300, handle_page_fault)
606
607	EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
608	EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
609	EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE)
610	EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_EE)
611	EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_EE)
612	EXCEPTION(0x1a00, Trap_1a, unknown_exception, EXC_XFER_EE)
613	EXCEPTION(0x1b00, Trap_1b, unknown_exception, EXC_XFER_EE)
614
615/* On the MPC8xx, these next four traps are used for development
616 * support of breakpoints and such.  Someday I will get around to
617 * using them.
618 */
619	. = 0x1c00
620DataBreakpoint:
621	EXCEPTION_PROLOG_0
622	mfcr	r10
623	mfspr	r11, SPRN_SRR0
624	cmplwi	cr0, r11, (dtlbie - PAGE_OFFSET)@l
625	cmplwi	cr7, r11, (itlbie - PAGE_OFFSET)@l
626	beq-	cr0, 11f
627	beq-	cr7, 11f
628	EXCEPTION_PROLOG_1
629	EXCEPTION_PROLOG_2
630	addi	r3,r1,STACK_FRAME_OVERHEAD
631	mfspr	r4,SPRN_BAR
632	stw	r4,_DAR(r11)
633	mfspr	r5,SPRN_DSISR
634	EXC_XFER_EE(0x1c00, do_break)
63511:
636	mtcr	r10
637	EXCEPTION_EPILOG_0
638	rfi
639
640#ifdef CONFIG_PPC_8xx_PERF_EVENT
641	. = 0x1d00
642InstructionBreakpoint:
643	EXCEPTION_PROLOG_0
644	lis	r10, (instruction_counter - PAGE_OFFSET)@ha
645	lwz	r11, (instruction_counter - PAGE_OFFSET)@l(r10)
646	addi	r11, r11, -1
647	stw	r11, (instruction_counter - PAGE_OFFSET)@l(r10)
648	lis	r10, 0xffff
649	ori	r10, r10, 0x01
650	mtspr	SPRN_COUNTA, r10
651	EXCEPTION_EPILOG_0
652	rfi
653#else
654	EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_EE)
655#endif
656	EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_EE)
657	EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_EE)
658
659	. = 0x2000
660
661/*
662 * Bottom part of DataStoreTLBMiss handlers for IMMR area and linear RAM.
663 * not enough space in the DataStoreTLBMiss area.
664 */
665DTLBMissIMMR:
666	mtcr	r3
667	/* Set 512k byte guarded page and mark it valid */
668	li	r10, MD_PS512K | MD_GUARDED | MD_SVALID
669	MTSPR_CPU6(SPRN_MD_TWC, r10, r11)
670	mfspr	r10, SPRN_IMMR			/* Get current IMMR */
671	rlwinm	r10, r10, 0, 0xfff80000		/* Get 512 kbytes boundary */
672	ori	r10, r10, 0xf0 | MD_SPS16K | _PAGE_SHARED | _PAGE_DIRTY	| \
673			  _PAGE_PRESENT | _PAGE_NO_CACHE
674	MTSPR_CPU6(SPRN_MD_RPN, r10, r11)	/* Update TLB entry */
675
676	li	r11, RPN_PATTERN
677	mtspr	SPRN_DAR, r11	/* Tag DAR */
678	mfspr	r3, SPRN_SPRG_SCRATCH2
679	EXCEPTION_EPILOG_0
680	rfi
681
682DTLBMissLinear:
683	mtcr	r3
684	/* Set 8M byte page and mark it valid */
685	li	r11, MD_PS8MEG | MD_SVALID
686	MTSPR_CPU6(SPRN_MD_TWC, r11, r3)
687	rlwinm	r10, r10, 16, 0x0f800000	/* 8xx supports max 256Mb RAM */
688	ori	r10, r10, 0xf0 | MD_SPS16K | _PAGE_SHARED | _PAGE_DIRTY	| \
689			  _PAGE_PRESENT
690	MTSPR_CPU6(SPRN_MD_RPN, r10, r11)	/* Update TLB entry */
691
692	li	r11, RPN_PATTERN
693	mtspr	SPRN_DAR, r11	/* Tag DAR */
694	mfspr	r3, SPRN_SPRG_SCRATCH2
695	EXCEPTION_EPILOG_0
696	rfi
697
698/* This is the procedure to calculate the data EA for buggy dcbx,dcbi instructions
699 * by decoding the registers used by the dcbx instruction and adding them.
700 * DAR is set to the calculated address.
701 */
702 /* define if you don't want to use self modifying code */
703#define NO_SELF_MODIFYING_CODE
704FixupDAR:/* Entry point for dcbx workaround. */
705	mtspr	SPRN_SPRG_SCRATCH2, r10
706	/* fetch instruction from memory. */
707	mfspr	r10, SPRN_SRR0
708	IS_KERNEL(r11, r10)
709	mfspr	r11, SPRN_M_TW	/* Get level 1 table */
710	BRANCH_UNLESS_KERNEL(3f)
711	rlwinm	r11, r10, 16, 0xfff8
712_ENTRY(FixupDAR_cmp)
713	cmpli	cr7, r11, (PAGE_OFFSET + 0x1800000)@h
714	/* create physical page address from effective address */
715	tophys(r11, r10)
716	blt-	cr7, 201f
717	lis	r11, (swapper_pg_dir-PAGE_OFFSET)@ha
718	/* Insert level 1 index */
7193:	rlwimi	r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
720	lwz	r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11)	/* Get the level 1 entry */
721	mtcr	r11
722	bt	28,200f		/* bit 28 = Large page (8M) */
723	bt	29,202f		/* bit 29 = Large page (8M or 512K) */
724	rlwinm	r11, r11,0,0,19	/* Extract page descriptor page address */
725	/* Insert level 2 index */
726	rlwimi	r11, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
727	lwz	r11, 0(r11)	/* Get the pte */
728	/* concat physical page address(r11) and page offset(r10) */
729	rlwimi	r11, r10, 0, 32 - PAGE_SHIFT, 31
730201:	lwz	r11,0(r11)
731/* Check if it really is a dcbx instruction. */
732/* dcbt and dcbtst does not generate DTLB Misses/Errors,
733 * no need to include them here */
734	xoris	r10, r11, 0x7c00	/* check if major OP code is 31 */
735	rlwinm	r10, r10, 0, 21, 5
736	cmpwi	cr0, r10, 2028	/* Is dcbz? */
737	beq+	142f
738	cmpwi	cr0, r10, 940	/* Is dcbi? */
739	beq+	142f
740	cmpwi	cr0, r10, 108	/* Is dcbst? */
741	beq+	144f		/* Fix up store bit! */
742	cmpwi	cr0, r10, 172	/* Is dcbf? */
743	beq+	142f
744	cmpwi	cr0, r10, 1964	/* Is icbi? */
745	beq+	142f
746141:	mfspr	r10,SPRN_SPRG_SCRATCH2
747	b	DARFixed	/* Nope, go back to normal TLB processing */
748
749	/* concat physical page address(r11) and page offset(r10) */
750200:
751#ifdef CONFIG_PPC_16K_PAGES
752	rlwinm	r11, r11, 0, 0, 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1) - 1
753	rlwimi	r11, r10, 32 - (PAGE_SHIFT_8M - 2), 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1), 29
754#else
755	rlwinm	r11, r10, 0, ~HUGEPD_SHIFT_MASK
756#endif
757	lwz	r11, 0(r11)	/* Get the pte */
758	/* concat physical page address(r11) and page offset(r10) */
759	rlwimi	r11, r10, 0, 32 - PAGE_SHIFT_8M, 31
760	b	201b
761
762202:
763	rlwinm	r11, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
764	rlwimi	r11, r10, 32 - (PAGE_SHIFT_512K - 2), 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1), 29
765	lwz	r11, 0(r11)	/* Get the pte */
766	/* concat physical page address(r11) and page offset(r10) */
767	rlwimi	r11, r10, 0, 32 - PAGE_SHIFT_512K, 31
768	b	201b
769
770144:	mfspr	r10, SPRN_DSISR
771	rlwinm	r10, r10,0,7,5	/* Clear store bit for buggy dcbst insn */
772	mtspr	SPRN_DSISR, r10
773142:	/* continue, it was a dcbx, dcbi instruction. */
774#ifndef NO_SELF_MODIFYING_CODE
775	andis.	r10,r11,0x1f	/* test if reg RA is r0 */
776	li	r10,modified_instr@l
777	dcbtst	r0,r10		/* touch for store */
778	rlwinm	r11,r11,0,0,20	/* Zero lower 10 bits */
779	oris	r11,r11,640	/* Transform instr. to a "add r10,RA,RB" */
780	ori	r11,r11,532
781	stw	r11,0(r10)	/* store add/and instruction */
782	dcbf	0,r10		/* flush new instr. to memory. */
783	icbi	0,r10		/* invalidate instr. cache line */
784	mfspr	r11, SPRN_SPRG_SCRATCH1	/* restore r11 */
785	mfspr	r10, SPRN_SPRG_SCRATCH0	/* restore r10 */
786	isync			/* Wait until new instr is loaded from memory */
787modified_instr:
788	.space	4		/* this is where the add instr. is stored */
789	bne+	143f
790	subf	r10,r0,r10	/* r10=r10-r0, only if reg RA is r0 */
791143:	mtdar	r10		/* store faulting EA in DAR */
792	mfspr	r10,SPRN_SPRG_SCRATCH2
793	b	DARFixed	/* Go back to normal TLB handling */
794#else
795	mfctr	r10
796	mtdar	r10			/* save ctr reg in DAR */
797	rlwinm	r10, r11, 24, 24, 28	/* offset into jump table for reg RB */
798	addi	r10, r10, 150f@l	/* add start of table */
799	mtctr	r10			/* load ctr with jump address */
800	xor	r10, r10, r10		/* sum starts at zero */
801	bctr				/* jump into table */
802150:
803	add	r10, r10, r0	;b	151f
804	add	r10, r10, r1	;b	151f
805	add	r10, r10, r2	;b	151f
806	add	r10, r10, r3	;b	151f
807	add	r10, r10, r4	;b	151f
808	add	r10, r10, r5	;b	151f
809	add	r10, r10, r6	;b	151f
810	add	r10, r10, r7	;b	151f
811	add	r10, r10, r8	;b	151f
812	add	r10, r10, r9	;b	151f
813	mtctr	r11	;b	154f	/* r10 needs special handling */
814	mtctr	r11	;b	153f	/* r11 needs special handling */
815	add	r10, r10, r12	;b	151f
816	add	r10, r10, r13	;b	151f
817	add	r10, r10, r14	;b	151f
818	add	r10, r10, r15	;b	151f
819	add	r10, r10, r16	;b	151f
820	add	r10, r10, r17	;b	151f
821	add	r10, r10, r18	;b	151f
822	add	r10, r10, r19	;b	151f
823	add	r10, r10, r20	;b	151f
824	add	r10, r10, r21	;b	151f
825	add	r10, r10, r22	;b	151f
826	add	r10, r10, r23	;b	151f
827	add	r10, r10, r24	;b	151f
828	add	r10, r10, r25	;b	151f
829	add	r10, r10, r26	;b	151f
830	add	r10, r10, r27	;b	151f
831	add	r10, r10, r28	;b	151f
832	add	r10, r10, r29	;b	151f
833	add	r10, r10, r30	;b	151f
834	add	r10, r10, r31
835151:
836	rlwinm. r11,r11,19,24,28	/* offset into jump table for reg RA */
837	beq	152f			/* if reg RA is zero, don't add it */
838	addi	r11, r11, 150b@l	/* add start of table */
839	mtctr	r11			/* load ctr with jump address */
840	rlwinm	r11,r11,0,16,10		/* make sure we don't execute this more than once */
841	bctr				/* jump into table */
842152:
843	mfdar	r11
844	mtctr	r11			/* restore ctr reg from DAR */
845	mtdar	r10			/* save fault EA to DAR */
846	mfspr	r10,SPRN_SPRG_SCRATCH2
847	b	DARFixed		/* Go back to normal TLB handling */
848
849	/* special handling for r10,r11 since these are modified already */
850153:	mfspr	r11, SPRN_SPRG_SCRATCH1	/* load r11 from SPRN_SPRG_SCRATCH1 */
851	add	r10, r10, r11	/* add it */
852	mfctr	r11		/* restore r11 */
853	b	151b
854154:	mfspr	r11, SPRN_SPRG_SCRATCH0	/* load r10 from SPRN_SPRG_SCRATCH0 */
855	add	r10, r10, r11	/* add it */
856	mfctr	r11		/* restore r11 */
857	b	151b
858#endif
859
860/*
861 * This is where the main kernel code starts.
862 */
863start_here:
864	/* ptr to current */
865	lis	r2,init_task@h
866	ori	r2,r2,init_task@l
867
868	/* ptr to phys current thread */
869	tophys(r4,r2)
870	addi	r4,r4,THREAD	/* init task's THREAD */
871	mtspr	SPRN_SPRG_THREAD,r4
872
873	/* stack */
874	lis	r1,init_thread_union@ha
875	addi	r1,r1,init_thread_union@l
876	li	r0,0
877	stwu	r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
878
879	bl	early_init	/* We have to do this with MMU on */
880
881/*
882 * Decide what sort of machine this is and initialize the MMU.
883 */
884	li	r3,0
885	mr	r4,r31
886	bl	machine_init
887	bl	MMU_init
888
889/*
890 * Go back to running unmapped so we can load up new values
891 * and change to using our exception vectors.
892 * On the 8xx, all we have to do is invalidate the TLB to clear
893 * the old 8M byte TLB mappings and load the page table base register.
894 */
895	/* The right way to do this would be to track it down through
896	 * init's THREAD like the context switch code does, but this is
897	 * easier......until someone changes init's static structures.
898	 */
899	lis	r6, swapper_pg_dir@ha
900	tophys(r6,r6)
901#ifdef CONFIG_8xx_CPU6
902	lis	r4, cpu6_errata_word@h
903	ori	r4, r4, cpu6_errata_word@l
904	li	r3, 0x3f80
905	stw	r3, 12(r4)
906	lwz	r3, 12(r4)
907#endif
908	mtspr	SPRN_M_TW, r6
909	lis	r4,2f@h
910	ori	r4,r4,2f@l
911	tophys(r4,r4)
912	li	r3,MSR_KERNEL & ~(MSR_IR|MSR_DR)
913	mtspr	SPRN_SRR0,r4
914	mtspr	SPRN_SRR1,r3
915	rfi
916/* Load up the kernel context */
9172:
918	SYNC			/* Force all PTE updates to finish */
919	tlbia			/* Clear all TLB entries */
920	sync			/* wait for tlbia/tlbie to finish */
921	TLBSYNC			/* ... on all CPUs */
922
923	/* set up the PTE pointers for the Abatron bdiGDB.
924	*/
925	tovirt(r6,r6)
926	lis	r5, abatron_pteptrs@h
927	ori	r5, r5, abatron_pteptrs@l
928	stw	r5, 0xf0(r0)	/* Must match your Abatron config file */
929	tophys(r5,r5)
930	stw	r6, 0(r5)
931
932/* Now turn on the MMU for real! */
933	li	r4,MSR_KERNEL
934	lis	r3,start_kernel@h
935	ori	r3,r3,start_kernel@l
936	mtspr	SPRN_SRR0,r3
937	mtspr	SPRN_SRR1,r4
938	rfi			/* enable MMU and jump to start_kernel */
939
940/* Set up the initial MMU state so we can do the first level of
941 * kernel initialization.  This maps the first 8 MBytes of memory 1:1
942 * virtual to physical.  Also, set the cache mode since that is defined
943 * by TLB entries and perform any additional mapping (like of the IMMR).
944 * If configured to pin some TLBs, we pin the first 8 Mbytes of kernel,
945 * 24 Mbytes of data, and the 512k IMMR space.  Anything not covered by
946 * these mappings is mapped by page tables.
947 */
948initial_mmu:
949	li	r8, 0
950	mtspr	SPRN_MI_CTR, r8		/* remove PINNED ITLB entries */
951	lis	r10, MD_RESETVAL@h
952#ifndef CONFIG_8xx_COPYBACK
953	oris	r10, r10, MD_WTDEF@h
954#endif
955	mtspr	SPRN_MD_CTR, r10	/* remove PINNED DTLB entries */
956
957	tlbia			/* Invalidate all TLB entries */
958/* Always pin the first 8 MB ITLB to prevent ITLB
959   misses while mucking around with SRR0/SRR1 in asm
960*/
961	lis	r8, MI_RSV4I@h
962	ori	r8, r8, 0x1c00
963
964	mtspr	SPRN_MI_CTR, r8	/* Set instruction MMU control */
965
966#ifdef CONFIG_PIN_TLB
967	oris	r10, r10, MD_RSV4I@h
968	mtspr	SPRN_MD_CTR, r10	/* Set data TLB control */
969#endif
970
971	/* Now map the lower 8 Meg into the ITLB. */
972	lis	r8, KERNELBASE@h	/* Create vaddr for TLB */
973	ori	r8, r8, MI_EVALID	/* Mark it valid */
974	mtspr	SPRN_MI_EPN, r8
975	li	r8, MI_PS8MEG | (2 << 5)	/* Set 8M byte page, APG 2 */
976	ori	r8, r8, MI_SVALID	/* Make it valid */
977	mtspr	SPRN_MI_TWC, r8
978	li	r8, MI_BOOTINIT		/* Create RPN for address 0 */
979	mtspr	SPRN_MI_RPN, r8		/* Store TLB entry */
980
981	lis	r8, MI_APG_INIT@h	/* Set protection modes */
982	ori	r8, r8, MI_APG_INIT@l
983	mtspr	SPRN_MI_AP, r8
984	lis	r8, MD_APG_INIT@h
985	ori	r8, r8, MD_APG_INIT@l
986	mtspr	SPRN_MD_AP, r8
987
988	/* Map a 512k page for the IMMR to get the processor
989	 * internal registers (among other things).
990	 */
991#ifdef CONFIG_PIN_TLB_IMMR
992	ori	r10, r10, 0x1c00
993	mtspr	SPRN_MD_CTR, r10
994
995	mfspr	r9, 638			/* Get current IMMR */
996	andis.	r9, r9, 0xfff8		/* Get 512 kbytes boundary */
997
998	lis	r8, VIRT_IMMR_BASE@h	/* Create vaddr for TLB */
999	ori	r8, r8, MD_EVALID	/* Mark it valid */
1000	mtspr	SPRN_MD_EPN, r8
1001	li	r8, MD_PS512K | MD_GUARDED	/* Set 512k byte page */
1002	ori	r8, r8, MD_SVALID	/* Make it valid */
1003	mtspr	SPRN_MD_TWC, r8
1004	mr	r8, r9			/* Create paddr for TLB */
1005	ori	r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */
1006	mtspr	SPRN_MD_RPN, r8
1007#endif
1008
1009	/* Since the cache is enabled according to the information we
1010	 * just loaded into the TLB, invalidate and enable the caches here.
1011	 * We should probably check/set other modes....later.
1012	 */
1013	lis	r8, IDC_INVALL@h
1014	mtspr	SPRN_IC_CST, r8
1015	mtspr	SPRN_DC_CST, r8
1016	lis	r8, IDC_ENABLE@h
1017	mtspr	SPRN_IC_CST, r8
1018#ifdef CONFIG_8xx_COPYBACK
1019	mtspr	SPRN_DC_CST, r8
1020#else
1021	/* For a debug option, I left this here to easily enable
1022	 * the write through cache mode
1023	 */
1024	lis	r8, DC_SFWT@h
1025	mtspr	SPRN_DC_CST, r8
1026	lis	r8, IDC_ENABLE@h
1027	mtspr	SPRN_DC_CST, r8
1028#endif
1029	/* Disable debug mode entry on breakpoints */
1030	mfspr	r8, SPRN_DER
1031#ifdef CONFIG_PPC_8xx_PERF_EVENT
1032	rlwinm	r8, r8, 0, ~0xc
1033#else
1034	rlwinm	r8, r8, 0, ~0x8
1035#endif
1036	mtspr	SPRN_DER, r8
1037	blr
1038
1039
1040/*
1041 * We put a few things here that have to be page-aligned.
1042 * This stuff goes at the beginning of the data segment,
1043 * which is page-aligned.
1044 */
1045	.data
1046	.globl	sdata
1047sdata:
1048	.globl	empty_zero_page
1049	.align	PAGE_SHIFT
1050empty_zero_page:
1051	.space	PAGE_SIZE
1052EXPORT_SYMBOL(empty_zero_page)
1053
1054	.globl	swapper_pg_dir
1055swapper_pg_dir:
1056	.space	PGD_TABLE_SIZE
1057
1058/* Room for two PTE table poiners, usually the kernel and current user
1059 * pointer to their respective root page table (pgdir).
1060 */
1061abatron_pteptrs:
1062	.space	8
1063
1064#ifdef CONFIG_8xx_CPU6
1065	.globl	cpu6_errata_word
1066cpu6_errata_word:
1067	.space	16
1068#endif
1069
1070#ifdef CONFIG_PPC_8xx_PERF_EVENT
1071	.globl	itlb_miss_counter
1072itlb_miss_counter:
1073	.space	4
1074
1075	.globl	dtlb_miss_counter
1076dtlb_miss_counter:
1077	.space	4
1078
1079	.globl	instruction_counter
1080instruction_counter:
1081	.space	4
1082#endif
1083