xref: /openbmc/linux/arch/powerpc/kernel/head_8xx.S (revision b593bce5) 
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 *  PowerPC version
4 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
5 *  Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
6 *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
7 *  Low-level exception handlers and MMU support
8 *  rewritten by Paul Mackerras.
9 *    Copyright (C) 1996 Paul Mackerras.
10 *  MPC8xx modifications by Dan Malek
11 *    Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
12 *
13 *  This file contains low-level support and setup for PowerPC 8xx
14 *  embedded processors, including trap and interrupt dispatch.
15 */
16
17#include <linux/init.h>
18#include <asm/processor.h>
19#include <asm/page.h>
20#include <asm/mmu.h>
21#include <asm/cache.h>
22#include <asm/pgtable.h>
23#include <asm/cputable.h>
24#include <asm/thread_info.h>
25#include <asm/ppc_asm.h>
26#include <asm/asm-offsets.h>
27#include <asm/ptrace.h>
28#include <asm/export.h>
29#include <asm/code-patching-asm.h>
30
31#include "head_32.h"
32
33#if CONFIG_TASK_SIZE <= 0x80000000 && CONFIG_PAGE_OFFSET >= 0x80000000
34/* By simply checking Address >= 0x80000000, we know if its a kernel address */
35#define SIMPLE_KERNEL_ADDRESS		1
36#endif
37
38/*
39 * We need an ITLB miss handler for kernel addresses if:
40 * - Either we have modules
41 * - Or we have not pinned the first 8M
42 */
43#if defined(CONFIG_MODULES) || !defined(CONFIG_PIN_TLB_TEXT) || \
44    defined(CONFIG_DEBUG_PAGEALLOC)
45#define ITLB_MISS_KERNEL	1
46#endif
47
48/*
49 * Value for the bits that have fixed value in RPN entries.
50 * Also used for tagging DAR for DTLBerror.
51 */
52#define RPN_PATTERN	0x00f0
53
54#define PAGE_SHIFT_512K		19
55#define PAGE_SHIFT_8M		23
56
57	__HEAD
58_ENTRY(_stext);
59_ENTRY(_start);
60
61/* MPC8xx
62 * This port was done on an MBX board with an 860.  Right now I only
63 * support an ELF compressed (zImage) boot from EPPC-Bug because the
64 * code there loads up some registers before calling us:
65 *   r3: ptr to board info data
66 *   r4: initrd_start or if no initrd then 0
67 *   r5: initrd_end - unused if r4 is 0
68 *   r6: Start of command line string
69 *   r7: End of command line string
70 *
71 * I decided to use conditional compilation instead of checking PVR and
72 * adding more processor specific branches around code I don't need.
73 * Since this is an embedded processor, I also appreciate any memory
74 * savings I can get.
75 *
76 * The MPC8xx does not have any BATs, but it supports large page sizes.
77 * We first initialize the MMU to support 8M byte pages, then load one
78 * entry into each of the instruction and data TLBs to map the first
79 * 8M 1:1.  I also mapped an additional I/O space 1:1 so we can get to
80 * the "internal" processor registers before MMU_init is called.
81 *
82 *	-- Dan
83 */
84	.globl	__start
85__start:
86	mr	r31,r3			/* save device tree ptr */
87
88	/* We have to turn on the MMU right away so we get cache modes
89	 * set correctly.
90	 */
91	bl	initial_mmu
92
93/* We now have the lower 8 Meg mapped into TLB entries, and the caches
94 * ready to work.
95 */
96
97turn_on_mmu:
98	mfmsr	r0
99	ori	r0,r0,MSR_DR|MSR_IR
100	mtspr	SPRN_SRR1,r0
101	lis	r0,start_here@h
102	ori	r0,r0,start_here@l
103	mtspr	SPRN_SRR0,r0
104	rfi				/* enables MMU */
105
106
107#ifdef CONFIG_PERF_EVENTS
108	.align	4
109
110	.globl	itlb_miss_counter
111itlb_miss_counter:
112	.space	4
113
114	.globl	dtlb_miss_counter
115dtlb_miss_counter:
116	.space	4
117
118	.globl	instruction_counter
119instruction_counter:
120	.space	4
121#endif
122
123/* System reset */
124	EXCEPTION(0x100, Reset, system_reset_exception, EXC_XFER_STD)
125
126/* Machine check */
127	. = 0x200
128MachineCheck:
129	EXCEPTION_PROLOG
130	mfspr r4,SPRN_DAR
131	stw r4,_DAR(r11)
132	li r5,RPN_PATTERN
133	mtspr SPRN_DAR,r5	/* Tag DAR, to be used in DTLB Error */
134	mfspr r5,SPRN_DSISR
135	stw r5,_DSISR(r11)
136	addi r3,r1,STACK_FRAME_OVERHEAD
137	EXC_XFER_STD(0x200, machine_check_exception)
138
139/* Data access exception.
140 * This is "never generated" by the MPC8xx.
141 */
142	. = 0x300
143DataAccess:
144
145/* Instruction access exception.
146 * This is "never generated" by the MPC8xx.
147 */
148	. = 0x400
149InstructionAccess:
150
151/* External interrupt */
152	EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
153
154/* Alignment exception */
155	. = 0x600
156Alignment:
157	EXCEPTION_PROLOG
158	mfspr	r4,SPRN_DAR
159	stw	r4,_DAR(r11)
160	li	r5,RPN_PATTERN
161	mtspr	SPRN_DAR,r5	/* Tag DAR, to be used in DTLB Error */
162	mfspr	r5,SPRN_DSISR
163	stw	r5,_DSISR(r11)
164	addi	r3,r1,STACK_FRAME_OVERHEAD
165	EXC_XFER_STD(0x600, alignment_exception)
166
167/* Program check exception */
168	EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)
169
170/* No FPU on MPC8xx.  This exception is not supposed to happen.
171*/
172	EXCEPTION(0x800, FPUnavailable, unknown_exception, EXC_XFER_STD)
173
174/* Decrementer */
175	EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE)
176
177	EXCEPTION(0xa00, Trap_0a, unknown_exception, EXC_XFER_STD)
178	EXCEPTION(0xb00, Trap_0b, unknown_exception, EXC_XFER_STD)
179
180/* System call */
181	. = 0xc00
182SystemCall:
183	SYSCALL_ENTRY	0xc00
184
185/* Single step - not used on 601 */
186	EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)
187	EXCEPTION(0xe00, Trap_0e, unknown_exception, EXC_XFER_STD)
188	EXCEPTION(0xf00, Trap_0f, unknown_exception, EXC_XFER_STD)
189
190/* On the MPC8xx, this is a software emulation interrupt.  It occurs
191 * for all unimplemented and illegal instructions.
192 */
193	EXCEPTION(0x1000, SoftEmu, program_check_exception, EXC_XFER_STD)
194
195/* Called from DataStoreTLBMiss when perf TLB misses events are activated */
196#ifdef CONFIG_PERF_EVENTS
197	patch_site	0f, patch__dtlbmiss_perf
1980:	lwz	r10, (dtlb_miss_counter - PAGE_OFFSET)@l(0)
199	addi	r10, r10, 1
200	stw	r10, (dtlb_miss_counter - PAGE_OFFSET)@l(0)
201	mfspr	r10, SPRN_SPRG_SCRATCH0
202	mfspr	r11, SPRN_SPRG_SCRATCH1
203	rfi
204#endif
205
206	. = 0x1100
207/*
208 * For the MPC8xx, this is a software tablewalk to load the instruction
209 * TLB.  The task switch loads the M_TWB register with the pointer to the first
210 * level table.
211 * If we discover there is no second level table (value is zero) or if there
212 * is an invalid pte, we load that into the TLB, which causes another fault
213 * into the TLB Error interrupt where we can handle such problems.
214 * We have to use the MD_xxx registers for the tablewalk because the
215 * equivalent MI_xxx registers only perform the attribute functions.
216 */
217
218#ifdef CONFIG_8xx_CPU15
219#define INVALIDATE_ADJACENT_PAGES_CPU15(addr)	\
220	addi	addr, addr, PAGE_SIZE;	\
221	tlbie	addr;			\
222	addi	addr, addr, -(PAGE_SIZE << 1);	\
223	tlbie	addr;			\
224	addi	addr, addr, PAGE_SIZE
225#else
226#define INVALIDATE_ADJACENT_PAGES_CPU15(addr)
227#endif
228
229InstructionTLBMiss:
230	mtspr	SPRN_SPRG_SCRATCH0, r10
231#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_SWAP)
232	mtspr	SPRN_SPRG_SCRATCH1, r11
233#endif
234
235	/* If we are faulting a kernel address, we have to use the
236	 * kernel page tables.
237	 */
238	mfspr	r10, SPRN_SRR0	/* Get effective address of fault */
239	INVALIDATE_ADJACENT_PAGES_CPU15(r10)
240	mtspr	SPRN_MD_EPN, r10
241	/* Only modules will cause ITLB Misses as we always
242	 * pin the first 8MB of kernel memory */
243#ifdef ITLB_MISS_KERNEL
244	mfcr	r11
245#if defined(SIMPLE_KERNEL_ADDRESS) && defined(CONFIG_PIN_TLB_TEXT)
246	cmpi	cr0, r10, 0	/* Address >= 0x80000000 */
247#else
248	rlwinm	r10, r10, 16, 0xfff8
249	cmpli	cr0, r10, PAGE_OFFSET@h
250#ifndef CONFIG_PIN_TLB_TEXT
251	/* It is assumed that kernel code fits into the first 32M */
2520:	cmpli	cr7, r10, (PAGE_OFFSET + 0x2000000)@h
253	patch_site	0b, patch__itlbmiss_linmem_top
254#endif
255#endif
256#endif
257	mfspr	r10, SPRN_M_TWB	/* Get level 1 table */
258#ifdef ITLB_MISS_KERNEL
259#if defined(SIMPLE_KERNEL_ADDRESS) && defined(CONFIG_PIN_TLB_TEXT)
260	bge+	3f
261#else
262	blt+	3f
263#endif
264#ifndef CONFIG_PIN_TLB_TEXT
265	blt	cr7, ITLBMissLinear
266#endif
267	rlwinm	r10, r10, 0, 20, 31
268	oris	r10, r10, (swapper_pg_dir - PAGE_OFFSET)@ha
2693:
270#endif
271	lwz	r10, (swapper_pg_dir-PAGE_OFFSET)@l(r10)	/* Get level 1 entry */
272	mtspr	SPRN_MI_TWC, r10	/* Set segment attributes */
273
274	mtspr	SPRN_MD_TWC, r10
275	mfspr	r10, SPRN_MD_TWC
276	lwz	r10, 0(r10)	/* Get the pte */
277#ifdef ITLB_MISS_KERNEL
278	mtcr	r11
279#endif
280#ifdef CONFIG_SWAP
281	rlwinm	r11, r10, 32-5, _PAGE_PRESENT
282	and	r11, r11, r10
283	rlwimi	r10, r11, 0, _PAGE_PRESENT
284#endif
285	/* The Linux PTE won't go exactly into the MMU TLB.
286	 * Software indicator bits 20 and 23 must be clear.
287	 * Software indicator bits 22, 24, 25, 26, and 27 must be
288	 * set.  All other Linux PTE bits control the behavior
289	 * of the MMU.
290	 */
291	rlwimi	r10, r10, 0, 0x0f00	/* Clear bits 20-23 */
292	rlwimi	r10, r10, 4, 0x0400	/* Copy _PAGE_EXEC into bit 21 */
293	ori	r10, r10, RPN_PATTERN | 0x200 /* Set 22 and 24-27 */
294	mtspr	SPRN_MI_RPN, r10	/* Update TLB entry */
295
296	/* Restore registers */
2970:	mfspr	r10, SPRN_SPRG_SCRATCH0
298#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_SWAP)
299	mfspr	r11, SPRN_SPRG_SCRATCH1
300#endif
301	rfi
302	patch_site	0b, patch__itlbmiss_exit_1
303
304#ifdef CONFIG_PERF_EVENTS
305	patch_site	0f, patch__itlbmiss_perf
3060:	lwz	r10, (itlb_miss_counter - PAGE_OFFSET)@l(0)
307	addi	r10, r10, 1
308	stw	r10, (itlb_miss_counter - PAGE_OFFSET)@l(0)
309	mfspr	r10, SPRN_SPRG_SCRATCH0
310#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_SWAP)
311	mfspr	r11, SPRN_SPRG_SCRATCH1
312#endif
313	rfi
314#endif
315
316#ifndef CONFIG_PIN_TLB_TEXT
317ITLBMissLinear:
318	mtcr	r11
319#if defined(CONFIG_STRICT_KERNEL_RWX) && CONFIG_ETEXT_SHIFT < 23
320	patch_site	0f, patch__itlbmiss_linmem_top8
321
322	mfspr	r10, SPRN_SRR0
3230:	subis	r11, r10, (PAGE_OFFSET - 0x80000000)@ha
324	rlwinm	r11, r11, 4, MI_PS8MEG ^ MI_PS512K
325	ori	r11, r11, MI_PS512K | MI_SVALID
326	rlwinm	r10, r10, 0, 0x0ff80000	/* 8xx supports max 256Mb RAM */
327#else
328	/* Set 8M byte page and mark it valid */
329	li	r11, MI_PS8MEG | MI_SVALID
330	rlwinm	r10, r10, 20, 0x0f800000	/* 8xx supports max 256Mb RAM */
331#endif
332	mtspr	SPRN_MI_TWC, r11
333	ori	r10, r10, 0xf0 | MI_SPS16K | _PAGE_SH | _PAGE_DIRTY | \
334			  _PAGE_PRESENT
335	mtspr	SPRN_MI_RPN, r10	/* Update TLB entry */
336
3370:	mfspr	r10, SPRN_SPRG_SCRATCH0
338	mfspr	r11, SPRN_SPRG_SCRATCH1
339	rfi
340	patch_site	0b, patch__itlbmiss_exit_2
341#endif
342
343	. = 0x1200
344DataStoreTLBMiss:
345	mtspr	SPRN_SPRG_SCRATCH0, r10
346	mtspr	SPRN_SPRG_SCRATCH1, r11
347	mfcr	r11
348
349	/* If we are faulting a kernel address, we have to use the
350	 * kernel page tables.
351	 */
352	mfspr	r10, SPRN_MD_EPN
353	rlwinm	r10, r10, 16, 0xfff8
354	cmpli	cr0, r10, PAGE_OFFSET@h
355#ifndef CONFIG_PIN_TLB_IMMR
356	cmpli	cr6, r10, VIRT_IMMR_BASE@h
357#endif
3580:	cmpli	cr7, r10, (PAGE_OFFSET + 0x2000000)@h
359	patch_site	0b, patch__dtlbmiss_linmem_top
360
361	mfspr	r10, SPRN_M_TWB	/* Get level 1 table */
362	blt+	3f
363#ifndef CONFIG_PIN_TLB_IMMR
3640:	beq-	cr6, DTLBMissIMMR
365	patch_site	0b, patch__dtlbmiss_immr_jmp
366#endif
367	blt	cr7, DTLBMissLinear
368	rlwinm	r10, r10, 0, 20, 31
369	oris	r10, r10, (swapper_pg_dir - PAGE_OFFSET)@ha
3703:
371	mtcr	r11
372	lwz	r11, (swapper_pg_dir-PAGE_OFFSET)@l(r10)	/* Get level 1 entry */
373
374	mtspr	SPRN_MD_TWC, r11
375	mfspr	r10, SPRN_MD_TWC
376	lwz	r10, 0(r10)	/* Get the pte */
377
378	/* Insert the Guarded flag into the TWC from the Linux PTE.
379	 * It is bit 27 of both the Linux PTE and the TWC (at least
380	 * I got that right :-).  It will be better when we can put
381	 * this into the Linux pgd/pmd and load it in the operation
382	 * above.
383	 */
384	rlwimi	r11, r10, 0, _PAGE_GUARDED
385	mtspr	SPRN_MD_TWC, r11
386
387	/* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
388	 * We also need to know if the insn is a load/store, so:
389	 * Clear _PAGE_PRESENT and load that which will
390	 * trap into DTLB Error with store bit set accordinly.
391	 */
392	/* PRESENT=0x1, ACCESSED=0x20
393	 * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5));
394	 * r10 = (r10 & ~PRESENT) | r11;
395	 */
396#ifdef CONFIG_SWAP
397	rlwinm	r11, r10, 32-5, _PAGE_PRESENT
398	and	r11, r11, r10
399	rlwimi	r10, r11, 0, _PAGE_PRESENT
400#endif
401	/* The Linux PTE won't go exactly into the MMU TLB.
402	 * Software indicator bits 24, 25, 26, and 27 must be
403	 * set.  All other Linux PTE bits control the behavior
404	 * of the MMU.
405	 */
406	li	r11, RPN_PATTERN
407	rlwimi	r10, r11, 0, 24, 27	/* Set 24-27 */
408	mtspr	SPRN_MD_RPN, r10	/* Update TLB entry */
409
410	/* Restore registers */
411	mtspr	SPRN_DAR, r11	/* Tag DAR */
412
4130:	mfspr	r10, SPRN_SPRG_SCRATCH0
414	mfspr	r11, SPRN_SPRG_SCRATCH1
415	rfi
416	patch_site	0b, patch__dtlbmiss_exit_1
417
418DTLBMissIMMR:
419	mtcr	r11
420	/* Set 512k byte guarded page and mark it valid */
421	li	r10, MD_PS512K | MD_GUARDED | MD_SVALID
422	mtspr	SPRN_MD_TWC, r10
423	mfspr	r10, SPRN_IMMR			/* Get current IMMR */
424	rlwinm	r10, r10, 0, 0xfff80000		/* Get 512 kbytes boundary */
425	ori	r10, r10, 0xf0 | MD_SPS16K | _PAGE_SH | _PAGE_DIRTY | \
426			  _PAGE_PRESENT | _PAGE_NO_CACHE
427	mtspr	SPRN_MD_RPN, r10	/* Update TLB entry */
428
429	li	r11, RPN_PATTERN
430	mtspr	SPRN_DAR, r11	/* Tag DAR */
431
4320:	mfspr	r10, SPRN_SPRG_SCRATCH0
433	mfspr	r11, SPRN_SPRG_SCRATCH1
434	rfi
435	patch_site	0b, patch__dtlbmiss_exit_2
436
437DTLBMissLinear:
438	mtcr	r11
439	rlwinm	r10, r10, 20, 0x0f800000	/* 8xx supports max 256Mb RAM */
440#if defined(CONFIG_STRICT_KERNEL_RWX) && CONFIG_DATA_SHIFT < 23
441	patch_site	0f, patch__dtlbmiss_romem_top8
442
4430:	subis	r11, r10, (PAGE_OFFSET - 0x80000000)@ha
444	rlwinm	r11, r11, 0, 0xff800000
445	neg	r10, r11
446	or	r11, r11, r10
447	rlwinm	r11, r11, 4, MI_PS8MEG ^ MI_PS512K
448	ori	r11, r11, MI_PS512K | MI_SVALID
449	mfspr	r10, SPRN_MD_EPN
450	rlwinm	r10, r10, 0, 0x0ff80000	/* 8xx supports max 256Mb RAM */
451#else
452	/* Set 8M byte page and mark it valid */
453	li	r11, MD_PS8MEG | MD_SVALID
454#endif
455	mtspr	SPRN_MD_TWC, r11
456#ifdef CONFIG_STRICT_KERNEL_RWX
457	patch_site	0f, patch__dtlbmiss_romem_top
458
4590:	subis	r11, r10, 0
460	rlwimi	r10, r11, 11, _PAGE_RO
461#endif
462	ori	r10, r10, 0xf0 | MD_SPS16K | _PAGE_SH | _PAGE_DIRTY | \
463			  _PAGE_PRESENT
464	mtspr	SPRN_MD_RPN, r10	/* Update TLB entry */
465
466	li	r11, RPN_PATTERN
467	mtspr	SPRN_DAR, r11	/* Tag DAR */
468
4690:	mfspr	r10, SPRN_SPRG_SCRATCH0
470	mfspr	r11, SPRN_SPRG_SCRATCH1
471	rfi
472	patch_site	0b, patch__dtlbmiss_exit_3
473
474/* This is an instruction TLB error on the MPC8xx.  This could be due
475 * to many reasons, such as executing guarded memory or illegal instruction
476 * addresses.  There is nothing to do but handle a big time error fault.
477 */
478	. = 0x1300
479InstructionTLBError:
480	EXCEPTION_PROLOG
481	mr	r4,r12
482	andis.	r5,r9,DSISR_SRR1_MATCH_32S@h /* Filter relevant SRR1 bits */
483	andis.	r10,r9,SRR1_ISI_NOPT@h
484	beq+	.Litlbie
485	tlbie	r4
486	/* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
487.Litlbie:
488	EXC_XFER_LITE(0x400, handle_page_fault)
489
490/* This is the data TLB error on the MPC8xx.  This could be due to
491 * many reasons, including a dirty update to a pte.  We bail out to
492 * a higher level function that can handle it.
493 */
494	. = 0x1400
495DataTLBError:
496	mtspr	SPRN_SPRG_SCRATCH0, r10
497	mtspr	SPRN_SPRG_SCRATCH1, r11
498	mfcr	r10
499
500	mfspr	r11, SPRN_DAR
501	cmpwi	cr0, r11, RPN_PATTERN
502	beq-	FixupDAR	/* must be a buggy dcbX, icbi insn. */
503DARFixed:/* Return from dcbx instruction bug workaround */
504	EXCEPTION_PROLOG_1
505	EXCEPTION_PROLOG_2
506	mfspr	r5,SPRN_DSISR
507	stw	r5,_DSISR(r11)
508	mfspr	r4,SPRN_DAR
509	andis.	r10,r5,DSISR_NOHPTE@h
510	beq+	.Ldtlbie
511	tlbie	r4
512.Ldtlbie:
513	li	r10,RPN_PATTERN
514	mtspr	SPRN_DAR,r10	/* Tag DAR, to be used in DTLB Error */
515	/* 0x300 is DataAccess exception, needed by bad_page_fault() */
516	EXC_XFER_LITE(0x300, handle_page_fault)
517
518	EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_STD)
519	EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_STD)
520	EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_STD)
521	EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_STD)
522	EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_STD)
523	EXCEPTION(0x1a00, Trap_1a, unknown_exception, EXC_XFER_STD)
524	EXCEPTION(0x1b00, Trap_1b, unknown_exception, EXC_XFER_STD)
525
526/* On the MPC8xx, these next four traps are used for development
527 * support of breakpoints and such.  Someday I will get around to
528 * using them.
529 */
530	. = 0x1c00
531DataBreakpoint:
532	mtspr	SPRN_SPRG_SCRATCH0, r10
533	mtspr	SPRN_SPRG_SCRATCH1, r11
534	mfcr	r10
535	mfspr	r11, SPRN_SRR0
536	cmplwi	cr0, r11, (.Ldtlbie - PAGE_OFFSET)@l
537	cmplwi	cr7, r11, (.Litlbie - PAGE_OFFSET)@l
538	beq-	cr0, 11f
539	beq-	cr7, 11f
540	EXCEPTION_PROLOG_1
541	EXCEPTION_PROLOG_2
542	addi	r3,r1,STACK_FRAME_OVERHEAD
543	mfspr	r4,SPRN_BAR
544	stw	r4,_DAR(r11)
545	mfspr	r5,SPRN_DSISR
546	EXC_XFER_STD(0x1c00, do_break)
54711:
548	mtcr	r10
549	mfspr	r10, SPRN_SPRG_SCRATCH0
550	mfspr	r11, SPRN_SPRG_SCRATCH1
551	rfi
552
553#ifdef CONFIG_PERF_EVENTS
554	. = 0x1d00
555InstructionBreakpoint:
556	mtspr	SPRN_SPRG_SCRATCH0, r10
557	lwz	r10, (instruction_counter - PAGE_OFFSET)@l(0)
558	addi	r10, r10, -1
559	stw	r10, (instruction_counter - PAGE_OFFSET)@l(0)
560	lis	r10, 0xffff
561	ori	r10, r10, 0x01
562	mtspr	SPRN_COUNTA, r10
563	mfspr	r10, SPRN_SPRG_SCRATCH0
564	rfi
565#else
566	EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_STD)
567#endif
568	EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_STD)
569	EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_STD)
570
571	. = 0x2000
572
573/* This is the procedure to calculate the data EA for buggy dcbx,dcbi instructions
574 * by decoding the registers used by the dcbx instruction and adding them.
575 * DAR is set to the calculated address.
576 */
577 /* define if you don't want to use self modifying code */
578#define NO_SELF_MODIFYING_CODE
579FixupDAR:/* Entry point for dcbx workaround. */
580	mtspr	SPRN_M_TW, r10
581	/* fetch instruction from memory. */
582	mfspr	r10, SPRN_SRR0
583	mtspr	SPRN_MD_EPN, r10
584	rlwinm	r11, r10, 16, 0xfff8
585	cmpli	cr0, r11, PAGE_OFFSET@h
586	mfspr	r11, SPRN_M_TWB	/* Get level 1 table */
587	blt+	3f
588	rlwinm	r11, r10, 16, 0xfff8
589
5900:	cmpli	cr7, r11, (PAGE_OFFSET + 0x1800000)@h
591	patch_site	0b, patch__fixupdar_linmem_top
592
593	/* create physical page address from effective address */
594	tophys(r11, r10)
595	blt-	cr7, 201f
596	mfspr	r11, SPRN_M_TWB	/* Get level 1 table */
597	rlwinm	r11, r11, 0, 20, 31
598	oris	r11, r11, (swapper_pg_dir - PAGE_OFFSET)@ha
5993:
600	lwz	r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11)	/* Get the level 1 entry */
601	mtspr	SPRN_MD_TWC, r11
602	mtcr	r11
603	mfspr	r11, SPRN_MD_TWC
604	lwz	r11, 0(r11)	/* Get the pte */
605	bt	28,200f		/* bit 28 = Large page (8M) */
606	bt	29,202f		/* bit 29 = Large page (8M or 512K) */
607	/* concat physical page address(r11) and page offset(r10) */
608	rlwimi	r11, r10, 0, 32 - PAGE_SHIFT, 31
609201:	lwz	r11,0(r11)
610/* Check if it really is a dcbx instruction. */
611/* dcbt and dcbtst does not generate DTLB Misses/Errors,
612 * no need to include them here */
613	xoris	r10, r11, 0x7c00	/* check if major OP code is 31 */
614	rlwinm	r10, r10, 0, 21, 5
615	cmpwi	cr0, r10, 2028	/* Is dcbz? */
616	beq+	142f
617	cmpwi	cr0, r10, 940	/* Is dcbi? */
618	beq+	142f
619	cmpwi	cr0, r10, 108	/* Is dcbst? */
620	beq+	144f		/* Fix up store bit! */
621	cmpwi	cr0, r10, 172	/* Is dcbf? */
622	beq+	142f
623	cmpwi	cr0, r10, 1964	/* Is icbi? */
624	beq+	142f
625141:	mfspr	r10,SPRN_M_TW
626	b	DARFixed	/* Nope, go back to normal TLB processing */
627
628200:
629	/* concat physical page address(r11) and page offset(r10) */
630	rlwimi	r11, r10, 0, 32 - PAGE_SHIFT_8M, 31
631	b	201b
632
633202:
634	/* concat physical page address(r11) and page offset(r10) */
635	rlwimi	r11, r10, 0, 32 - PAGE_SHIFT_512K, 31
636	b	201b
637
638144:	mfspr	r10, SPRN_DSISR
639	rlwinm	r10, r10,0,7,5	/* Clear store bit for buggy dcbst insn */
640	mtspr	SPRN_DSISR, r10
641142:	/* continue, it was a dcbx, dcbi instruction. */
642#ifndef NO_SELF_MODIFYING_CODE
643	andis.	r10,r11,0x1f	/* test if reg RA is r0 */
644	li	r10,modified_instr@l
645	dcbtst	r0,r10		/* touch for store */
646	rlwinm	r11,r11,0,0,20	/* Zero lower 10 bits */
647	oris	r11,r11,640	/* Transform instr. to a "add r10,RA,RB" */
648	ori	r11,r11,532
649	stw	r11,0(r10)	/* store add/and instruction */
650	dcbf	0,r10		/* flush new instr. to memory. */
651	icbi	0,r10		/* invalidate instr. cache line */
652	mfspr	r11, SPRN_SPRG_SCRATCH1	/* restore r11 */
653	mfspr	r10, SPRN_SPRG_SCRATCH0	/* restore r10 */
654	isync			/* Wait until new instr is loaded from memory */
655modified_instr:
656	.space	4		/* this is where the add instr. is stored */
657	bne+	143f
658	subf	r10,r0,r10	/* r10=r10-r0, only if reg RA is r0 */
659143:	mtdar	r10		/* store faulting EA in DAR */
660	mfspr	r10,SPRN_M_TW
661	b	DARFixed	/* Go back to normal TLB handling */
662#else
663	mfctr	r10
664	mtdar	r10			/* save ctr reg in DAR */
665	rlwinm	r10, r11, 24, 24, 28	/* offset into jump table for reg RB */
666	addi	r10, r10, 150f@l	/* add start of table */
667	mtctr	r10			/* load ctr with jump address */
668	xor	r10, r10, r10		/* sum starts at zero */
669	bctr				/* jump into table */
670150:
671	add	r10, r10, r0	;b	151f
672	add	r10, r10, r1	;b	151f
673	add	r10, r10, r2	;b	151f
674	add	r10, r10, r3	;b	151f
675	add	r10, r10, r4	;b	151f
676	add	r10, r10, r5	;b	151f
677	add	r10, r10, r6	;b	151f
678	add	r10, r10, r7	;b	151f
679	add	r10, r10, r8	;b	151f
680	add	r10, r10, r9	;b	151f
681	mtctr	r11	;b	154f	/* r10 needs special handling */
682	mtctr	r11	;b	153f	/* r11 needs special handling */
683	add	r10, r10, r12	;b	151f
684	add	r10, r10, r13	;b	151f
685	add	r10, r10, r14	;b	151f
686	add	r10, r10, r15	;b	151f
687	add	r10, r10, r16	;b	151f
688	add	r10, r10, r17	;b	151f
689	add	r10, r10, r18	;b	151f
690	add	r10, r10, r19	;b	151f
691	add	r10, r10, r20	;b	151f
692	add	r10, r10, r21	;b	151f
693	add	r10, r10, r22	;b	151f
694	add	r10, r10, r23	;b	151f
695	add	r10, r10, r24	;b	151f
696	add	r10, r10, r25	;b	151f
697	add	r10, r10, r26	;b	151f
698	add	r10, r10, r27	;b	151f
699	add	r10, r10, r28	;b	151f
700	add	r10, r10, r29	;b	151f
701	add	r10, r10, r30	;b	151f
702	add	r10, r10, r31
703151:
704	rlwinm. r11,r11,19,24,28	/* offset into jump table for reg RA */
705	beq	152f			/* if reg RA is zero, don't add it */
706	addi	r11, r11, 150b@l	/* add start of table */
707	mtctr	r11			/* load ctr with jump address */
708	rlwinm	r11,r11,0,16,10		/* make sure we don't execute this more than once */
709	bctr				/* jump into table */
710152:
711	mfdar	r11
712	mtctr	r11			/* restore ctr reg from DAR */
713	mtdar	r10			/* save fault EA to DAR */
714	mfspr	r10,SPRN_M_TW
715	b	DARFixed		/* Go back to normal TLB handling */
716
717	/* special handling for r10,r11 since these are modified already */
718153:	mfspr	r11, SPRN_SPRG_SCRATCH1	/* load r11 from SPRN_SPRG_SCRATCH1 */
719	add	r10, r10, r11	/* add it */
720	mfctr	r11		/* restore r11 */
721	b	151b
722154:	mfspr	r11, SPRN_SPRG_SCRATCH0	/* load r10 from SPRN_SPRG_SCRATCH0 */
723	add	r10, r10, r11	/* add it */
724	mfctr	r11		/* restore r11 */
725	b	151b
726#endif
727
728/*
729 * This is where the main kernel code starts.
730 */
731start_here:
732	/* ptr to current */
733	lis	r2,init_task@h
734	ori	r2,r2,init_task@l
735
736	/* ptr to phys current thread */
737	tophys(r4,r2)
738	addi	r4,r4,THREAD	/* init task's THREAD */
739	mtspr	SPRN_SPRG_THREAD,r4
740
741	/* stack */
742	lis	r1,init_thread_union@ha
743	addi	r1,r1,init_thread_union@l
744	li	r0,0
745	stwu	r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
746
747	lis	r6, swapper_pg_dir@ha
748	tophys(r6,r6)
749	mtspr	SPRN_M_TWB, r6
750
751	bl	early_init	/* We have to do this with MMU on */
752
753/*
754 * Decide what sort of machine this is and initialize the MMU.
755 */
756#ifdef CONFIG_KASAN
757	bl	kasan_early_init
758#endif
759	li	r3,0
760	mr	r4,r31
761	bl	machine_init
762	bl	MMU_init
763
764/*
765 * Go back to running unmapped so we can load up new values
766 * and change to using our exception vectors.
767 * On the 8xx, all we have to do is invalidate the TLB to clear
768 * the old 8M byte TLB mappings and load the page table base register.
769 */
770	/* The right way to do this would be to track it down through
771	 * init's THREAD like the context switch code does, but this is
772	 * easier......until someone changes init's static structures.
773	 */
774	lis	r4,2f@h
775	ori	r4,r4,2f@l
776	tophys(r4,r4)
777	li	r3,MSR_KERNEL & ~(MSR_IR|MSR_DR)
778	mtspr	SPRN_SRR0,r4
779	mtspr	SPRN_SRR1,r3
780	rfi
781/* Load up the kernel context */
7822:
783	tlbia			/* Clear all TLB entries */
784	sync			/* wait for tlbia/tlbie to finish */
785
786	/* set up the PTE pointers for the Abatron bdiGDB.
787	*/
788	lis	r5, abatron_pteptrs@h
789	ori	r5, r5, abatron_pteptrs@l
790	stw	r5, 0xf0(0)	/* Must match your Abatron config file */
791	tophys(r5,r5)
792	lis	r6, swapper_pg_dir@h
793	ori	r6, r6, swapper_pg_dir@l
794	stw	r6, 0(r5)
795
796/* Now turn on the MMU for real! */
797	li	r4,MSR_KERNEL
798	lis	r3,start_kernel@h
799	ori	r3,r3,start_kernel@l
800	mtspr	SPRN_SRR0,r3
801	mtspr	SPRN_SRR1,r4
802	rfi			/* enable MMU and jump to start_kernel */
803
804/* Set up the initial MMU state so we can do the first level of
805 * kernel initialization.  This maps the first 8 MBytes of memory 1:1
806 * virtual to physical.  Also, set the cache mode since that is defined
807 * by TLB entries and perform any additional mapping (like of the IMMR).
808 * If configured to pin some TLBs, we pin the first 8 Mbytes of kernel,
809 * 24 Mbytes of data, and the 512k IMMR space.  Anything not covered by
810 * these mappings is mapped by page tables.
811 */
812initial_mmu:
813	li	r8, 0
814	mtspr	SPRN_MI_CTR, r8		/* remove PINNED ITLB entries */
815	lis	r10, MD_RESETVAL@h
816#ifndef CONFIG_8xx_COPYBACK
817	oris	r10, r10, MD_WTDEF@h
818#endif
819	mtspr	SPRN_MD_CTR, r10	/* remove PINNED DTLB entries */
820
821	tlbia			/* Invalidate all TLB entries */
822#ifdef CONFIG_PIN_TLB_DATA
823	oris	r10, r10, MD_RSV4I@h
824	mtspr	SPRN_MD_CTR, r10	/* Set data TLB control */
825#endif
826
827	lis	r8, MI_APG_INIT@h	/* Set protection modes */
828	ori	r8, r8, MI_APG_INIT@l
829	mtspr	SPRN_MI_AP, r8
830	lis	r8, MD_APG_INIT@h
831	ori	r8, r8, MD_APG_INIT@l
832	mtspr	SPRN_MD_AP, r8
833
834	/* Map a 512k page for the IMMR to get the processor
835	 * internal registers (among other things).
836	 */
837#ifdef CONFIG_PIN_TLB_IMMR
838	oris	r10, r10, MD_RSV4I@h
839	ori	r10, r10, 0x1c00
840	mtspr	SPRN_MD_CTR, r10
841
842	mfspr	r9, 638			/* Get current IMMR */
843	andis.	r9, r9, 0xfff8		/* Get 512 kbytes boundary */
844
845	lis	r8, VIRT_IMMR_BASE@h	/* Create vaddr for TLB */
846	ori	r8, r8, MD_EVALID	/* Mark it valid */
847	mtspr	SPRN_MD_EPN, r8
848	li	r8, MD_PS512K | MD_GUARDED	/* Set 512k byte page */
849	ori	r8, r8, MD_SVALID	/* Make it valid */
850	mtspr	SPRN_MD_TWC, r8
851	mr	r8, r9			/* Create paddr for TLB */
852	ori	r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */
853	mtspr	SPRN_MD_RPN, r8
854#endif
855
856	/* Now map the lower RAM (up to 32 Mbytes) into the ITLB. */
857#ifdef CONFIG_PIN_TLB_TEXT
858	lis	r8, MI_RSV4I@h
859	ori	r8, r8, 0x1c00
860#endif
861	li	r9, 4				/* up to 4 pages of 8M */
862	mtctr	r9
863	lis	r9, KERNELBASE@h		/* Create vaddr for TLB */
864	li	r10, MI_PS8MEG | MI_SVALID	/* Set 8M byte page */
865	li	r11, MI_BOOTINIT		/* Create RPN for address 0 */
866	lis	r12, _einittext@h
867	ori	r12, r12, _einittext@l
8681:
869#ifdef CONFIG_PIN_TLB_TEXT
870	mtspr	SPRN_MI_CTR, r8	/* Set instruction MMU control */
871	addi	r8, r8, 0x100
872#endif
873
874	ori	r0, r9, MI_EVALID		/* Mark it valid */
875	mtspr	SPRN_MI_EPN, r0
876	mtspr	SPRN_MI_TWC, r10
877	mtspr	SPRN_MI_RPN, r11		/* Store TLB entry */
878	addis	r9, r9, 0x80
879	addis	r11, r11, 0x80
880
881	cmpl	cr0, r9, r12
882	bdnzf	gt, 1b
883
884	/* Since the cache is enabled according to the information we
885	 * just loaded into the TLB, invalidate and enable the caches here.
886	 * We should probably check/set other modes....later.
887	 */
888	lis	r8, IDC_INVALL@h
889	mtspr	SPRN_IC_CST, r8
890	mtspr	SPRN_DC_CST, r8
891	lis	r8, IDC_ENABLE@h
892	mtspr	SPRN_IC_CST, r8
893#ifdef CONFIG_8xx_COPYBACK
894	mtspr	SPRN_DC_CST, r8
895#else
896	/* For a debug option, I left this here to easily enable
897	 * the write through cache mode
898	 */
899	lis	r8, DC_SFWT@h
900	mtspr	SPRN_DC_CST, r8
901	lis	r8, IDC_ENABLE@h
902	mtspr	SPRN_DC_CST, r8
903#endif
904	/* Disable debug mode entry on breakpoints */
905	mfspr	r8, SPRN_DER
906#ifdef CONFIG_PERF_EVENTS
907	rlwinm	r8, r8, 0, ~0xc
908#else
909	rlwinm	r8, r8, 0, ~0x8
910#endif
911	mtspr	SPRN_DER, r8
912	blr
913
914
915/*
916 * We put a few things here that have to be page-aligned.
917 * This stuff goes at the beginning of the data segment,
918 * which is page-aligned.
919 */
920	.data
921	.globl	sdata
922sdata:
923	.globl	empty_zero_page
924	.align	PAGE_SHIFT
925empty_zero_page:
926	.space	PAGE_SIZE
927EXPORT_SYMBOL(empty_zero_page)
928
929	.globl	swapper_pg_dir
930swapper_pg_dir:
931	.space	PGD_TABLE_SIZE
932
933/* Room for two PTE table poiners, usually the kernel and current user
934 * pointer to their respective root page table (pgdir).
935 */
936	.globl	abatron_pteptrs
937abatron_pteptrs:
938	.space	8
939