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1/*
2 * Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org>
3 * Initial PowerPC version.
4 * Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu>
5 * Rewritten for PReP
6 * Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au>
7 * Low-level exception handers, MMU support, and rewrite.
8 * Copyright (c) 1997 Dan Malek <dmalek@jlc.net>
9 * PowerPC 8xx modifications.
10 * Copyright (c) 1998-1999 TiVo, Inc.
11 * PowerPC 403GCX modifications.
12 * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu>
13 * PowerPC 403GCX/405GP modifications.
14 * Copyright 2000 MontaVista Software Inc.
15 * PPC405 modifications
16 * PowerPC 403GCX/405GP modifications.
17 * Author: MontaVista Software, Inc.
18 * frank_rowand@mvista.com or source@mvista.com
19 * debbie_chu@mvista.com
20 *
21 *
22 * Module name: head_4xx.S
23 *
24 * Description:
25 * Kernel execution entry point code.
26 *
27 * This program is free software; you can redistribute it and/or
28 * modify it under the terms of the GNU General Public License
29 * as published by the Free Software Foundation; either version
30 * 2 of the License, or (at your option) any later version.
31 *
32 */
33
34#include <linux/config.h>
35#include <asm/processor.h>
36#include <asm/page.h>
37#include <asm/mmu.h>
38#include <asm/pgtable.h>
39#include <asm/ibm4xx.h>
40#include <asm/cputable.h>
41#include <asm/thread_info.h>
42#include <asm/ppc_asm.h>
43#include <asm/offsets.h>
44
45/* As with the other PowerPC ports, it is expected that when code
46 * execution begins here, the following registers contain valid, yet
47 * optional, information:
48 *
49 * r3 - Board info structure pointer (DRAM, frequency, MAC address, etc.)
50 * r4 - Starting address of the init RAM disk
51 * r5 - Ending address of the init RAM disk
52 * r6 - Start of kernel command line string (e.g. "mem=96m")
53 * r7 - End of kernel command line string
54 *
55 * This is all going to change RSN when we add bi_recs....... -- Dan
56 */
57 .text
58_GLOBAL(_stext)
59_GLOBAL(_start)
60
61 /* Save parameters we are passed.
62 */
63 mr r31,r3
64 mr r30,r4
65 mr r29,r5
66 mr r28,r6
67 mr r27,r7
68
69 /* We have to turn on the MMU right away so we get cache modes
70 * set correctly.
71 */
72 bl initial_mmu
73
74/* We now have the lower 16 Meg mapped into TLB entries, and the caches
75 * ready to work.
76 */
77turn_on_mmu:
78 lis r0,MSR_KERNEL@h
79 ori r0,r0,MSR_KERNEL@l
80 mtspr SPRN_SRR1,r0
81 lis r0,start_here@h
82 ori r0,r0,start_here@l
83 mtspr SPRN_SRR0,r0
84 SYNC
85 rfi /* enables MMU */
86 b . /* prevent prefetch past rfi */
87
88/*
89 * This area is used for temporarily saving registers during the
90 * critical exception prolog.
91 */
92 . = 0xc0
93crit_save:
94_GLOBAL(crit_r10)
95 .space 4
96_GLOBAL(crit_r11)
97 .space 4
98
99/*
100 * Exception vector entry code. This code runs with address translation
101 * turned off (i.e. using physical addresses). We assume SPRG3 has the
102 * physical address of the current task thread_struct.
103 * Note that we have to have decremented r1 before we write to any fields
104 * of the exception frame, since a critical interrupt could occur at any
105 * time, and it will write to the area immediately below the current r1.
106 */
107#define NORMAL_EXCEPTION_PROLOG \
108 mtspr SPRN_SPRG0,r10; /* save two registers to work with */\
109 mtspr SPRN_SPRG1,r11; \
110 mtspr SPRN_SPRG2,r1; \
111 mfcr r10; /* save CR in r10 for now */\
112 mfspr r11,SPRN_SRR1; /* check whether user or kernel */\
113 andi. r11,r11,MSR_PR; \
114 beq 1f; \
115 mfspr r1,SPRN_SPRG3; /* if from user, start at top of */\
116 lwz r1,THREAD_INFO-THREAD(r1); /* this thread's kernel stack */\
117 addi r1,r1,THREAD_SIZE; \
1181: subi r1,r1,INT_FRAME_SIZE; /* Allocate an exception frame */\
119 tophys(r11,r1); \
120 stw r10,_CCR(r11); /* save various registers */\
121 stw r12,GPR12(r11); \
122 stw r9,GPR9(r11); \
123 mfspr r10,SPRN_SPRG0; \
124 stw r10,GPR10(r11); \
125 mfspr r12,SPRN_SPRG1; \
126 stw r12,GPR11(r11); \
127 mflr r10; \
128 stw r10,_LINK(r11); \
129 mfspr r10,SPRN_SPRG2; \
130 mfspr r12,SPRN_SRR0; \
131 stw r10,GPR1(r11); \
132 mfspr r9,SPRN_SRR1; \
133 stw r10,0(r11); \
134 rlwinm r9,r9,0,14,12; /* clear MSR_WE (necessary?) */\
135 stw r0,GPR0(r11); \
136 SAVE_4GPRS(3, r11); \
137 SAVE_2GPRS(7, r11)
138
139/*
140 * Exception prolog for critical exceptions. This is a little different
141 * from the normal exception prolog above since a critical exception
142 * can potentially occur at any point during normal exception processing.
143 * Thus we cannot use the same SPRG registers as the normal prolog above.
144 * Instead we use a couple of words of memory at low physical addresses.
145 * This is OK since we don't support SMP on these processors.
146 */
147#define CRITICAL_EXCEPTION_PROLOG \
148 stw r10,crit_r10@l(0); /* save two registers to work with */\
149 stw r11,crit_r11@l(0); \
150 mfcr r10; /* save CR in r10 for now */\
151 mfspr r11,SPRN_SRR3; /* check whether user or kernel */\
152 andi. r11,r11,MSR_PR; \
153 lis r11,critical_stack_top@h; \
154 ori r11,r11,critical_stack_top@l; \
155 beq 1f; \
156 /* COMING FROM USER MODE */ \
157 mfspr r11,SPRN_SPRG3; /* if from user, start at top of */\
158 lwz r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
159 addi r11,r11,THREAD_SIZE; \
1601: subi r11,r11,INT_FRAME_SIZE; /* Allocate an exception frame */\
161 tophys(r11,r11); \
162 stw r10,_CCR(r11); /* save various registers */\
163 stw r12,GPR12(r11); \
164 stw r9,GPR9(r11); \
165 mflr r10; \
166 stw r10,_LINK(r11); \
167 mfspr r12,SPRN_DEAR; /* save DEAR and ESR in the frame */\
168 stw r12,_DEAR(r11); /* since they may have had stuff */\
169 mfspr r9,SPRN_ESR; /* in them at the point where the */\
170 stw r9,_ESR(r11); /* exception was taken */\
171 mfspr r12,SPRN_SRR2; \
172 stw r1,GPR1(r11); \
173 mfspr r9,SPRN_SRR3; \
174 stw r1,0(r11); \
175 tovirt(r1,r11); \
176 rlwinm r9,r9,0,14,12; /* clear MSR_WE (necessary?) */\
177 stw r0,GPR0(r11); \
178 SAVE_4GPRS(3, r11); \
179 SAVE_2GPRS(7, r11)
180
181 /*
182 * State at this point:
183 * r9 saved in stack frame, now saved SRR3 & ~MSR_WE
184 * r10 saved in crit_r10 and in stack frame, trashed
185 * r11 saved in crit_r11 and in stack frame,
186 * now phys stack/exception frame pointer
187 * r12 saved in stack frame, now saved SRR2
188 * CR saved in stack frame, CR0.EQ = !SRR3.PR
189 * LR, DEAR, ESR in stack frame
190 * r1 saved in stack frame, now virt stack/excframe pointer
191 * r0, r3-r8 saved in stack frame
192 */
193
194/*
195 * Exception vectors.
196 */
197#define START_EXCEPTION(n, label) \
198 . = n; \
199label:
200
201#define EXCEPTION(n, label, hdlr, xfer) \
202 START_EXCEPTION(n, label); \
203 NORMAL_EXCEPTION_PROLOG; \
204 addi r3,r1,STACK_FRAME_OVERHEAD; \
205 xfer(n, hdlr)
206
207#define CRITICAL_EXCEPTION(n, label, hdlr) \
208 START_EXCEPTION(n, label); \
209 CRITICAL_EXCEPTION_PROLOG; \
210 addi r3,r1,STACK_FRAME_OVERHEAD; \
211 EXC_XFER_TEMPLATE(hdlr, n+2, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
212 NOCOPY, crit_transfer_to_handler, \
213 ret_from_crit_exc)
214
215#define EXC_XFER_TEMPLATE(hdlr, trap, msr, copyee, tfer, ret) \
216 li r10,trap; \
217 stw r10,TRAP(r11); \
218 lis r10,msr@h; \
219 ori r10,r10,msr@l; \
220 copyee(r10, r9); \
221 bl tfer; \
222 .long hdlr; \
223 .long ret
224
225#define COPY_EE(d, s) rlwimi d,s,0,16,16
226#define NOCOPY(d, s)
227
228#define EXC_XFER_STD(n, hdlr) \
229 EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, NOCOPY, transfer_to_handler_full, \
230 ret_from_except_full)
231
232#define EXC_XFER_LITE(n, hdlr) \
233 EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, NOCOPY, transfer_to_handler, \
234 ret_from_except)
235
236#define EXC_XFER_EE(n, hdlr) \
237 EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, COPY_EE, transfer_to_handler_full, \
238 ret_from_except_full)
239
240#define EXC_XFER_EE_LITE(n, hdlr) \
241 EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, COPY_EE, transfer_to_handler, \
242 ret_from_except)
243
244
245/*
246 * 0x0100 - Critical Interrupt Exception
247 */
248 CRITICAL_EXCEPTION(0x0100, CriticalInterrupt, UnknownException)
249
250/*
251 * 0x0200 - Machine Check Exception
252 */
253 CRITICAL_EXCEPTION(0x0200, MachineCheck, MachineCheckException)
254
255/*
256 * 0x0300 - Data Storage Exception
257 * This happens for just a few reasons. U0 set (but we don't do that),
258 * or zone protection fault (user violation, write to protected page).
259 * If this is just an update of modified status, we do that quickly
260 * and exit. Otherwise, we call heavywight functions to do the work.
261 */
262 START_EXCEPTION(0x0300, DataStorage)
263 mtspr SPRN_SPRG0, r10 /* Save some working registers */
264 mtspr SPRN_SPRG1, r11
265#ifdef CONFIG_403GCX
266 stw r12, 0(r0)
267 stw r9, 4(r0)
268 mfcr r11
269 mfspr r12, SPRN_PID
270 stw r11, 8(r0)
271 stw r12, 12(r0)
272#else
273 mtspr SPRN_SPRG4, r12
274 mtspr SPRN_SPRG5, r9
275 mfcr r11
276 mfspr r12, SPRN_PID
277 mtspr SPRN_SPRG7, r11
278 mtspr SPRN_SPRG6, r12
279#endif
280
281 /* First, check if it was a zone fault (which means a user
282 * tried to access a kernel or read-protected page - always
283 * a SEGV). All other faults here must be stores, so no
284 * need to check ESR_DST as well. */
285 mfspr r10, SPRN_ESR
286 andis. r10, r10, ESR_DIZ@h
287 bne 2f
288
289 mfspr r10, SPRN_DEAR /* Get faulting address */
290
291 /* If we are faulting a kernel address, we have to use the
292 * kernel page tables.
293 */
294 andis. r11, r10, 0x8000
295 beq 3f
296 lis r11, swapper_pg_dir@h
297 ori r11, r11, swapper_pg_dir@l
298 li r9, 0
299 mtspr SPRN_PID, r9 /* TLB will have 0 TID */
300 b 4f
301
302 /* Get the PGD for the current thread.
303 */
3043:
305 mfspr r11,SPRN_SPRG3
306 lwz r11,PGDIR(r11)
3074:
308 tophys(r11, r11)
309 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
310 lwz r11, 0(r11) /* Get L1 entry */
311 rlwinm. r12, r11, 0, 0, 19 /* Extract L2 (pte) base address */
312 beq 2f /* Bail if no table */
313
314 rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */
315 lwz r11, 0(r12) /* Get Linux PTE */
316
317 andi. r9, r11, _PAGE_RW /* Is it writeable? */
318 beq 2f /* Bail if not */
319
320 /* Update 'changed'.
321 */
322 ori r11, r11, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
323 stw r11, 0(r12) /* Update Linux page table */
324
325 /* Most of the Linux PTE is ready to load into the TLB LO.
326 * We set ZSEL, where only the LS-bit determines user access.
327 * We set execute, because we don't have the granularity to
328 * properly set this at the page level (Linux problem).
329 * If shared is set, we cause a zero PID->TID load.
330 * Many of these bits are software only. Bits we don't set
331 * here we (properly should) assume have the appropriate value.
332 */
333 li r12, 0x0ce2
334 andc r11, r11, r12 /* Make sure 20, 21 are zero */
335
336 /* find the TLB index that caused the fault. It has to be here.
337 */
338 tlbsx r9, 0, r10
339
340 tlbwe r11, r9, TLB_DATA /* Load TLB LO */
341
342 /* Done...restore registers and get out of here.
343 */
344#ifdef CONFIG_403GCX
345 lwz r12, 12(r0)
346 lwz r11, 8(r0)
347 mtspr SPRN_PID, r12
348 mtcr r11
349 lwz r9, 4(r0)
350 lwz r12, 0(r0)
351#else
352 mfspr r12, SPRN_SPRG6
353 mfspr r11, SPRN_SPRG7
354 mtspr SPRN_PID, r12
355 mtcr r11
356 mfspr r9, SPRN_SPRG5
357 mfspr r12, SPRN_SPRG4
358#endif
359 mfspr r11, SPRN_SPRG1
360 mfspr r10, SPRN_SPRG0
361 PPC405_ERR77_SYNC
362 rfi /* Should sync shadow TLBs */
363 b . /* prevent prefetch past rfi */
364
3652:
366 /* The bailout. Restore registers to pre-exception conditions
367 * and call the heavyweights to help us out.
368 */
369#ifdef CONFIG_403GCX
370 lwz r12, 12(r0)
371 lwz r11, 8(r0)
372 mtspr SPRN_PID, r12
373 mtcr r11
374 lwz r9, 4(r0)
375 lwz r12, 0(r0)
376#else
377 mfspr r12, SPRN_SPRG6
378 mfspr r11, SPRN_SPRG7
379 mtspr SPRN_PID, r12
380 mtcr r11
381 mfspr r9, SPRN_SPRG5
382 mfspr r12, SPRN_SPRG4
383#endif
384 mfspr r11, SPRN_SPRG1
385 mfspr r10, SPRN_SPRG0
386 b DataAccess
387
388/*
389 * 0x0400 - Instruction Storage Exception
390 * This is caused by a fetch from non-execute or guarded pages.
391 */
392 START_EXCEPTION(0x0400, InstructionAccess)
393 NORMAL_EXCEPTION_PROLOG
394 mr r4,r12 /* Pass SRR0 as arg2 */
395 li r5,0 /* Pass zero as arg3 */
396 EXC_XFER_EE_LITE(0x400, handle_page_fault)
397
398/* 0x0500 - External Interrupt Exception */
399 EXCEPTION(0x0500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
400
401/* 0x0600 - Alignment Exception */
402 START_EXCEPTION(0x0600, Alignment)
403 NORMAL_EXCEPTION_PROLOG
404 mfspr r4,SPRN_DEAR /* Grab the DEAR and save it */
405 stw r4,_DEAR(r11)
406 addi r3,r1,STACK_FRAME_OVERHEAD
407 EXC_XFER_EE(0x600, AlignmentException)
408
409/* 0x0700 - Program Exception */
410 START_EXCEPTION(0x0700, ProgramCheck)
411 NORMAL_EXCEPTION_PROLOG
412 mfspr r4,SPRN_ESR /* Grab the ESR and save it */
413 stw r4,_ESR(r11)
414 addi r3,r1,STACK_FRAME_OVERHEAD
415 EXC_XFER_STD(0x700, ProgramCheckException)
416
417 EXCEPTION(0x0800, Trap_08, UnknownException, EXC_XFER_EE)
418 EXCEPTION(0x0900, Trap_09, UnknownException, EXC_XFER_EE)
419 EXCEPTION(0x0A00, Trap_0A, UnknownException, EXC_XFER_EE)
420 EXCEPTION(0x0B00, Trap_0B, UnknownException, EXC_XFER_EE)
421
422/* 0x0C00 - System Call Exception */
423 START_EXCEPTION(0x0C00, SystemCall)
424 NORMAL_EXCEPTION_PROLOG
425 EXC_XFER_EE_LITE(0xc00, DoSyscall)
426
427 EXCEPTION(0x0D00, Trap_0D, UnknownException, EXC_XFER_EE)
428 EXCEPTION(0x0E00, Trap_0E, UnknownException, EXC_XFER_EE)
429 EXCEPTION(0x0F00, Trap_0F, UnknownException, EXC_XFER_EE)
430
431/* 0x1000 - Programmable Interval Timer (PIT) Exception */
432 START_EXCEPTION(0x1000, Decrementer)
433 NORMAL_EXCEPTION_PROLOG
434 lis r0,TSR_PIS@h
435 mtspr SPRN_TSR,r0 /* Clear the PIT exception */
436 addi r3,r1,STACK_FRAME_OVERHEAD
437 EXC_XFER_LITE(0x1000, timer_interrupt)
438
439#if 0
440/* NOTE:
441 * FIT and WDT handlers are not implemented yet.
442 */
443
444/* 0x1010 - Fixed Interval Timer (FIT) Exception
445*/
446 STND_EXCEPTION(0x1010, FITException, UnknownException)
447
448/* 0x1020 - Watchdog Timer (WDT) Exception
449*/
450
451 CRITICAL_EXCEPTION(0x1020, WDTException, UnknownException)
452#endif
453
454/* 0x1100 - Data TLB Miss Exception
455 * As the name implies, translation is not in the MMU, so search the
456 * page tables and fix it. The only purpose of this function is to
457 * load TLB entries from the page table if they exist.
458 */
459 START_EXCEPTION(0x1100, DTLBMiss)
460 mtspr SPRN_SPRG0, r10 /* Save some working registers */
461 mtspr SPRN_SPRG1, r11
462#ifdef CONFIG_403GCX
463 stw r12, 0(r0)
464 stw r9, 4(r0)
465 mfcr r11
466 mfspr r12, SPRN_PID
467 stw r11, 8(r0)
468 stw r12, 12(r0)
469#else
470 mtspr SPRN_SPRG4, r12
471 mtspr SPRN_SPRG5, r9
472 mfcr r11
473 mfspr r12, SPRN_PID
474 mtspr SPRN_SPRG7, r11
475 mtspr SPRN_SPRG6, r12
476#endif
477 mfspr r10, SPRN_DEAR /* Get faulting address */
478
479 /* If we are faulting a kernel address, we have to use the
480 * kernel page tables.
481 */
482 andis. r11, r10, 0x8000
483 beq 3f
484 lis r11, swapper_pg_dir@h
485 ori r11, r11, swapper_pg_dir@l
486 li r9, 0
487 mtspr SPRN_PID, r9 /* TLB will have 0 TID */
488 b 4f
489
490 /* Get the PGD for the current thread.
491 */
4923:
493 mfspr r11,SPRN_SPRG3
494 lwz r11,PGDIR(r11)
4954:
496 tophys(r11, r11)
497 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
498 lwz r12, 0(r11) /* Get L1 entry */
499 andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */
500 beq 2f /* Bail if no table */
501
502 rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */
503 lwz r11, 0(r12) /* Get Linux PTE */
504 andi. r9, r11, _PAGE_PRESENT
505 beq 5f
506
507 ori r11, r11, _PAGE_ACCESSED
508 stw r11, 0(r12)
509
510 /* Create TLB tag. This is the faulting address plus a static
511 * set of bits. These are size, valid, E, U0.
512 */
513 li r12, 0x00c0
514 rlwimi r10, r12, 0, 20, 31
515
516 b finish_tlb_load
517
5182: /* Check for possible large-page pmd entry */
519 rlwinm. r9, r12, 2, 22, 24
520 beq 5f
521
522 /* Create TLB tag. This is the faulting address, plus a static
523 * set of bits (valid, E, U0) plus the size from the PMD.
524 */
525 ori r9, r9, 0x40
526 rlwimi r10, r9, 0, 20, 31
527 mr r11, r12
528
529 b finish_tlb_load
530
5315:
532 /* The bailout. Restore registers to pre-exception conditions
533 * and call the heavyweights to help us out.
534 */
535#ifdef CONFIG_403GCX
536 lwz r12, 12(r0)
537 lwz r11, 8(r0)
538 mtspr SPRN_PID, r12
539 mtcr r11
540 lwz r9, 4(r0)
541 lwz r12, 0(r0)
542#else
543 mfspr r12, SPRN_SPRG6
544 mfspr r11, SPRN_SPRG7
545 mtspr SPRN_PID, r12
546 mtcr r11
547 mfspr r9, SPRN_SPRG5
548 mfspr r12, SPRN_SPRG4
549#endif
550 mfspr r11, SPRN_SPRG1
551 mfspr r10, SPRN_SPRG0
552 b DataAccess
553
554/* 0x1200 - Instruction TLB Miss Exception
555 * Nearly the same as above, except we get our information from different
556 * registers and bailout to a different point.
557 */
558 START_EXCEPTION(0x1200, ITLBMiss)
559 mtspr SPRN_SPRG0, r10 /* Save some working registers */
560 mtspr SPRN_SPRG1, r11
561#ifdef CONFIG_403GCX
562 stw r12, 0(r0)
563 stw r9, 4(r0)
564 mfcr r11
565 mfspr r12, SPRN_PID
566 stw r11, 8(r0)
567 stw r12, 12(r0)
568#else
569 mtspr SPRN_SPRG4, r12
570 mtspr SPRN_SPRG5, r9
571 mfcr r11
572 mfspr r12, SPRN_PID
573 mtspr SPRN_SPRG7, r11
574 mtspr SPRN_SPRG6, r12
575#endif
576 mfspr r10, SPRN_SRR0 /* Get faulting address */
577
578 /* If we are faulting a kernel address, we have to use the
579 * kernel page tables.
580 */
581 andis. r11, r10, 0x8000
582 beq 3f
583 lis r11, swapper_pg_dir@h
584 ori r11, r11, swapper_pg_dir@l
585 li r9, 0
586 mtspr SPRN_PID, r9 /* TLB will have 0 TID */
587 b 4f
588
589 /* Get the PGD for the current thread.
590 */
5913:
592 mfspr r11,SPRN_SPRG3
593 lwz r11,PGDIR(r11)
5944:
595 tophys(r11, r11)
596 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
597 lwz r12, 0(r11) /* Get L1 entry */
598 andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */
599 beq 2f /* Bail if no table */
600
601 rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */
602 lwz r11, 0(r12) /* Get Linux PTE */
603 andi. r9, r11, _PAGE_PRESENT
604 beq 5f
605
606 ori r11, r11, _PAGE_ACCESSED
607 stw r11, 0(r12)
608
609 /* Create TLB tag. This is the faulting address plus a static
610 * set of bits. These are size, valid, E, U0.
611 */
612 li r12, 0x00c0
613 rlwimi r10, r12, 0, 20, 31
614
615 b finish_tlb_load
616
6172: /* Check for possible large-page pmd entry */
618 rlwinm. r9, r12, 2, 22, 24
619 beq 5f
620
621 /* Create TLB tag. This is the faulting address, plus a static
622 * set of bits (valid, E, U0) plus the size from the PMD.
623 */
624 ori r9, r9, 0x40
625 rlwimi r10, r9, 0, 20, 31
626 mr r11, r12
627
628 b finish_tlb_load
629
6305:
631 /* The bailout. Restore registers to pre-exception conditions
632 * and call the heavyweights to help us out.
633 */
634#ifdef CONFIG_403GCX
635 lwz r12, 12(r0)
636 lwz r11, 8(r0)
637 mtspr SPRN_PID, r12
638 mtcr r11
639 lwz r9, 4(r0)
640 lwz r12, 0(r0)
641#else
642 mfspr r12, SPRN_SPRG6
643 mfspr r11, SPRN_SPRG7
644 mtspr SPRN_PID, r12
645 mtcr r11
646 mfspr r9, SPRN_SPRG5
647 mfspr r12, SPRN_SPRG4
648#endif
649 mfspr r11, SPRN_SPRG1
650 mfspr r10, SPRN_SPRG0
651 b InstructionAccess
652
653 EXCEPTION(0x1300, Trap_13, UnknownException, EXC_XFER_EE)
654 EXCEPTION(0x1400, Trap_14, UnknownException, EXC_XFER_EE)
655 EXCEPTION(0x1500, Trap_15, UnknownException, EXC_XFER_EE)
656 EXCEPTION(0x1600, Trap_16, UnknownException, EXC_XFER_EE)
657#ifdef CONFIG_IBM405_ERR51
658 /* 405GP errata 51 */
659 START_EXCEPTION(0x1700, Trap_17)
660 b DTLBMiss
661#else
662 EXCEPTION(0x1700, Trap_17, UnknownException, EXC_XFER_EE)
663#endif
664 EXCEPTION(0x1800, Trap_18, UnknownException, EXC_XFER_EE)
665 EXCEPTION(0x1900, Trap_19, UnknownException, EXC_XFER_EE)
666 EXCEPTION(0x1A00, Trap_1A, UnknownException, EXC_XFER_EE)
667 EXCEPTION(0x1B00, Trap_1B, UnknownException, EXC_XFER_EE)
668 EXCEPTION(0x1C00, Trap_1C, UnknownException, EXC_XFER_EE)
669 EXCEPTION(0x1D00, Trap_1D, UnknownException, EXC_XFER_EE)
670 EXCEPTION(0x1E00, Trap_1E, UnknownException, EXC_XFER_EE)
671 EXCEPTION(0x1F00, Trap_1F, UnknownException, EXC_XFER_EE)
672
673/* Check for a single step debug exception while in an exception
674 * handler before state has been saved. This is to catch the case
675 * where an instruction that we are trying to single step causes
676 * an exception (eg ITLB/DTLB miss) and thus the first instruction of
677 * the exception handler generates a single step debug exception.
678 *
679 * If we get a debug trap on the first instruction of an exception handler,
680 * we reset the MSR_DE in the _exception handler's_ MSR (the debug trap is
681 * a critical exception, so we are using SPRN_CSRR1 to manipulate the MSR).
682 * The exception handler was handling a non-critical interrupt, so it will
683 * save (and later restore) the MSR via SPRN_SRR1, which will still have
684 * the MSR_DE bit set.
685 */
686 /* 0x2000 - Debug Exception */
687 START_EXCEPTION(0x2000, DebugTrap)
688 CRITICAL_EXCEPTION_PROLOG
689
690 /*
691 * If this is a single step or branch-taken exception in an
692 * exception entry sequence, it was probably meant to apply to
693 * the code where the exception occurred (since exception entry
694 * doesn't turn off DE automatically). We simulate the effect
695 * of turning off DE on entry to an exception handler by turning
696 * off DE in the SRR3 value and clearing the debug status.
697 */
698 mfspr r10,SPRN_DBSR /* check single-step/branch taken */
699 andis. r10,r10,DBSR_IC@h
700 beq+ 2f
701
702 andi. r10,r9,MSR_IR|MSR_PR /* check supervisor + MMU off */
703 beq 1f /* branch and fix it up */
704
705 mfspr r10,SPRN_SRR2 /* Faulting instruction address */
706 cmplwi r10,0x2100
707 bgt+ 2f /* address above exception vectors */
708
709 /* here it looks like we got an inappropriate debug exception. */
7101: rlwinm r9,r9,0,~MSR_DE /* clear DE in the SRR3 value */
711 lis r10,DBSR_IC@h /* clear the IC event */
712 mtspr SPRN_DBSR,r10
713 /* restore state and get out */
714 lwz r10,_CCR(r11)
715 lwz r0,GPR0(r11)
716 lwz r1,GPR1(r11)
717 mtcrf 0x80,r10
718 mtspr SPRN_SRR2,r12
719 mtspr SPRN_SRR3,r9
720 lwz r9,GPR9(r11)
721 lwz r12,GPR12(r11)
722 lwz r10,crit_r10@l(0)
723 lwz r11,crit_r11@l(0)
724 PPC405_ERR77_SYNC
725 rfci
726 b .
727
728 /* continue normal handling for a critical exception... */
7292: mfspr r4,SPRN_DBSR
730 addi r3,r1,STACK_FRAME_OVERHEAD
731 EXC_XFER_TEMPLATE(DebugException, 0x2002, \
732 (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
733 NOCOPY, crit_transfer_to_handler, ret_from_crit_exc)
734
735/*
736 * The other Data TLB exceptions bail out to this point
737 * if they can't resolve the lightweight TLB fault.
738 */
739DataAccess:
740 NORMAL_EXCEPTION_PROLOG
741 mfspr r5,SPRN_ESR /* Grab the ESR, save it, pass arg3 */
742 stw r5,_ESR(r11)
743 mfspr r4,SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */
744 EXC_XFER_EE_LITE(0x300, handle_page_fault)
745
746/* Other PowerPC processors, namely those derived from the 6xx-series
747 * have vectors from 0x2100 through 0x2F00 defined, but marked as reserved.
748 * However, for the 4xx-series processors these are neither defined nor
749 * reserved.
750 */
751
752 /* Damn, I came up one instruction too many to fit into the
753 * exception space :-). Both the instruction and data TLB
754 * miss get to this point to load the TLB.
755 * r10 - TLB_TAG value
756 * r11 - Linux PTE
757 * r12, r9 - avilable to use
758 * PID - loaded with proper value when we get here
759 * Upon exit, we reload everything and RFI.
760 * Actually, it will fit now, but oh well.....a common place
761 * to load the TLB.
762 */
763tlb_4xx_index:
764 .long 0
765finish_tlb_load:
766 /* load the next available TLB index.
767 */
768 lwz r9, tlb_4xx_index@l(0)
769 addi r9, r9, 1
770 andi. r9, r9, (PPC4XX_TLB_SIZE-1)
771 stw r9, tlb_4xx_index@l(0)
772
7736:
774 /*
775 * Clear out the software-only bits in the PTE to generate the
776 * TLB_DATA value. These are the bottom 2 bits of the RPM, the
777 * top 3 bits of the zone field, and M.
778 */
779 li r12, 0x0ce2
780 andc r11, r11, r12
781
782 tlbwe r11, r9, TLB_DATA /* Load TLB LO */
783 tlbwe r10, r9, TLB_TAG /* Load TLB HI */
784
785 /* Done...restore registers and get out of here.
786 */
787#ifdef CONFIG_403GCX
788 lwz r12, 12(r0)
789 lwz r11, 8(r0)
790 mtspr SPRN_PID, r12
791 mtcr r11
792 lwz r9, 4(r0)
793 lwz r12, 0(r0)
794#else
795 mfspr r12, SPRN_SPRG6
796 mfspr r11, SPRN_SPRG7
797 mtspr SPRN_PID, r12
798 mtcr r11
799 mfspr r9, SPRN_SPRG5
800 mfspr r12, SPRN_SPRG4
801#endif
802 mfspr r11, SPRN_SPRG1
803 mfspr r10, SPRN_SPRG0
804 PPC405_ERR77_SYNC
805 rfi /* Should sync shadow TLBs */
806 b . /* prevent prefetch past rfi */
807
808/* extern void giveup_fpu(struct task_struct *prev)
809 *
810 * The PowerPC 4xx family of processors do not have an FPU, so this just
811 * returns.
812 */
813_GLOBAL(giveup_fpu)
814 blr
815
816/* This is where the main kernel code starts.
817 */
818start_here:
819
820 /* ptr to current */
821 lis r2,init_task@h
822 ori r2,r2,init_task@l
823
824 /* ptr to phys current thread */
825 tophys(r4,r2)
826 addi r4,r4,THREAD /* init task's THREAD */
827 mtspr SPRN_SPRG3,r4
828
829 /* stack */
830 lis r1,init_thread_union@ha
831 addi r1,r1,init_thread_union@l
832 li r0,0
833 stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
834
835 bl early_init /* We have to do this with MMU on */
836
837/*
838 * Decide what sort of machine this is and initialize the MMU.
839 */
840 mr r3,r31
841 mr r4,r30
842 mr r5,r29
843 mr r6,r28
844 mr r7,r27
845 bl machine_init
846 bl MMU_init
847
848/* Go back to running unmapped so we can load up new values
849 * and change to using our exception vectors.
850 * On the 4xx, all we have to do is invalidate the TLB to clear
851 * the old 16M byte TLB mappings.
852 */
853 lis r4,2f@h
854 ori r4,r4,2f@l
855 tophys(r4,r4)
856 lis r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@h
857 ori r3,r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@l
858 mtspr SPRN_SRR0,r4
859 mtspr SPRN_SRR1,r3
860 rfi
861 b . /* prevent prefetch past rfi */
862
863/* Load up the kernel context */
8642:
865 sync /* Flush to memory before changing TLB */
866 tlbia
867 isync /* Flush shadow TLBs */
868
869 /* set up the PTE pointers for the Abatron bdiGDB.
870 */
871 lis r6, swapper_pg_dir@h
872 ori r6, r6, swapper_pg_dir@l
873 lis r5, abatron_pteptrs@h
874 ori r5, r5, abatron_pteptrs@l
875 stw r5, 0xf0(r0) /* Must match your Abatron config file */
876 tophys(r5,r5)
877 stw r6, 0(r5)
878
879/* Now turn on the MMU for real! */
880 lis r4,MSR_KERNEL@h
881 ori r4,r4,MSR_KERNEL@l
882 lis r3,start_kernel@h
883 ori r3,r3,start_kernel@l
884 mtspr SPRN_SRR0,r3
885 mtspr SPRN_SRR1,r4
886 rfi /* enable MMU and jump to start_kernel */
887 b . /* prevent prefetch past rfi */
888
889/* Set up the initial MMU state so we can do the first level of
890 * kernel initialization. This maps the first 16 MBytes of memory 1:1
891 * virtual to physical and more importantly sets the cache mode.
892 */
893initial_mmu:
894 tlbia /* Invalidate all TLB entries */
895 isync
896
897 /* We should still be executing code at physical address 0x0000xxxx
898 * at this point. However, start_here is at virtual address
899 * 0xC000xxxx. So, set up a TLB mapping to cover this once
900 * translation is enabled.
901 */
902
903 lis r3,KERNELBASE@h /* Load the kernel virtual address */
904 ori r3,r3,KERNELBASE@l
905 tophys(r4,r3) /* Load the kernel physical address */
906
907 iccci r0,r3 /* Invalidate the i-cache before use */
908
909 /* Load the kernel PID.
910 */
911 li r0,0
912 mtspr SPRN_PID,r0
913 sync
914
915 /* Configure and load two entries into TLB slots 62 and 63.
916 * In case we are pinning TLBs, these are reserved in by the
917 * other TLB functions. If not reserving, then it doesn't
918 * matter where they are loaded.
919 */
920 clrrwi r4,r4,10 /* Mask off the real page number */
921 ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */
922
923 clrrwi r3,r3,10 /* Mask off the effective page number */
924 ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M))
925
926 li r0,63 /* TLB slot 63 */
927
928 tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */
929 tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */
930
931#if defined(CONFIG_SERIAL_TEXT_DEBUG) && defined(SERIAL_DEBUG_IO_BASE)
932
933 /* Load a TLB entry for the UART, so that ppc4xx_progress() can use
934 * the UARTs nice and early. We use a 4k real==virtual mapping. */
935
936 lis r3,SERIAL_DEBUG_IO_BASE@h
937 ori r3,r3,SERIAL_DEBUG_IO_BASE@l
938 mr r4,r3
939 clrrwi r4,r4,12
940 ori r4,r4,(TLB_WR|TLB_I|TLB_M|TLB_G)
941
942 clrrwi r3,r3,12
943 ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_4K))
944
945 li r0,0 /* TLB slot 0 */
946 tlbwe r4,r0,TLB_DATA
947 tlbwe r3,r0,TLB_TAG
948#endif /* CONFIG_SERIAL_DEBUG_TEXT && SERIAL_DEBUG_IO_BASE */
949
950 isync
951
952 /* Establish the exception vector base
953 */
954 lis r4,KERNELBASE@h /* EVPR only uses the high 16-bits */
955 tophys(r0,r4) /* Use the physical address */
956 mtspr SPRN_EVPR,r0
957
958 blr
959
960_GLOBAL(abort)
961 mfspr r13,SPRN_DBCR0
962 oris r13,r13,DBCR0_RST_SYSTEM@h
963 mtspr SPRN_DBCR0,r13
964
965_GLOBAL(set_context)
966
967#ifdef CONFIG_BDI_SWITCH
968 /* Context switch the PTE pointer for the Abatron BDI2000.
969 * The PGDIR is the second parameter.
970 */
971 lis r5, KERNELBASE@h
972 lwz r5, 0xf0(r5)
973 stw r4, 0x4(r5)
974#endif
975 sync
976 mtspr SPRN_PID,r3
977 isync /* Need an isync to flush shadow */
978 /* TLBs after changing PID */
979 blr
980
981/* We put a few things here that have to be page-aligned. This stuff
982 * goes at the beginning of the data segment, which is page-aligned.
983 */
984 .data
985_GLOBAL(sdata)
986_GLOBAL(empty_zero_page)
987 .space 4096
988_GLOBAL(swapper_pg_dir)
989 .space 4096
990
991
992/* Stack for handling critical exceptions from kernel mode */
993 .section .bss
994 .align 12
995exception_stack_bottom:
996 .space 4096
997critical_stack_top:
998_GLOBAL(exception_stack_top)
999
1000/* This space gets a copy of optional info passed to us by the bootstrap
1001 * which is used to pass parameters into the kernel like root=/dev/sda1, etc.
1002 */
1003_GLOBAL(cmd_line)
1004 .space 512
1005
1006/* Room for two PTE pointers, usually the kernel and current user pointers
1007 * to their respective root page table.
1008 */
1009abatron_pteptrs:
1010 .space 8
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-23 02:54:04 -0500