| blob | 9dd21a8c4d52ac3cef52923ea561c21347cf24b0 |
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 */
34 #include <linux/init.h>
35 #include <asm/processor.h>
36 #include <asm/page.h>
37 #include <asm/mmu.h>
38 #include <asm/pgtable.h>
39 #include <asm/cputable.h>
40 #include <asm/thread_info.h>
41 #include <asm/ppc_asm.h>
42 #include <asm/asm-offsets.h>
43 #include <asm/ptrace.h>
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 __HEAD
58 _ENTRY(_stext);
59 _ENTRY(_start);
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
69 /* We have to turn on the MMU right away so we get cache modes
70 * set correctly.
71 */
72 bl initial_mmu
74 /* We now have the lower 16 Meg mapped into TLB entries, and the caches
75 * ready to work.
76 */
77 turn_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 */
88 /*
89 * This area is used for temporarily saving registers during the
90 * critical exception prolog.
91 */
92 . = 0xc0
93 crit_save:
94 _ENTRY(crit_r10)
95 .space 4
96 _ENTRY(crit_r11)
97 .space 4
98 _ENTRY(crit_srr0)
99 .space 4
100 _ENTRY(crit_srr1)
101 .space 4
102 _ENTRY(saved_ksp_limit)
103 .space 4
105 /*
106 * Exception vector entry code. This code runs with address translation
107 * turned off (i.e. using physical addresses). We assume SPRG_THREAD has
108 * the physical address of the current task thread_struct.
109 * Note that we have to have decremented r1 before we write to any fields
110 * of the exception frame, since a critical interrupt could occur at any
111 * time, and it will write to the area immediately below the current r1.
112 */
113 #define NORMAL_EXCEPTION_PROLOG \
114 mtspr SPRN_SPRG_SCRATCH0,r10; /* save two registers to work with */\
115 mtspr SPRN_SPRG_SCRATCH1,r11; \
116 mtspr SPRN_SPRG_SCRATCH2,r1; \
117 mfcr r10; /* save CR in r10 for now */\
118 mfspr r11,SPRN_SRR1; /* check whether user or kernel */\
119 andi. r11,r11,MSR_PR; \
120 beq 1f; \
121 mfspr r1,SPRN_SPRG_THREAD; /* if from user, start at top of */\
122 lwz r1,THREAD_INFO-THREAD(r1); /* this thread's kernel stack */\
123 addi r1,r1,THREAD_SIZE; \
124 1: subi r1,r1,INT_FRAME_SIZE; /* Allocate an exception frame */\
125 tophys(r11,r1); \
126 stw r10,_CCR(r11); /* save various registers */\
127 stw r12,GPR12(r11); \
128 stw r9,GPR9(r11); \
129 mfspr r10,SPRN_SPRG_SCRATCH0; \
130 stw r10,GPR10(r11); \
131 mfspr r12,SPRN_SPRG_SCRATCH1; \
132 stw r12,GPR11(r11); \
133 mflr r10; \
134 stw r10,_LINK(r11); \
135 mfspr r10,SPRN_SPRG_SCRATCH2; \
136 mfspr r12,SPRN_SRR0; \
137 stw r10,GPR1(r11); \
138 mfspr r9,SPRN_SRR1; \
139 stw r10,0(r11); \
140 rlwinm r9,r9,0,14,12; /* clear MSR_WE (necessary?) */\
141 stw r0,GPR0(r11); \
142 SAVE_4GPRS(3, r11); \
143 SAVE_2GPRS(7, r11)
145 /*
146 * Exception prolog for critical exceptions. This is a little different
147 * from the normal exception prolog above since a critical exception
148 * can potentially occur at any point during normal exception processing.
149 * Thus we cannot use the same SPRG registers as the normal prolog above.
150 * Instead we use a couple of words of memory at low physical addresses.
151 * This is OK since we don't support SMP on these processors.
152 */
153 #define CRITICAL_EXCEPTION_PROLOG \
154 stw r10,crit_r10@l(0); /* save two registers to work with */\
155 stw r11,crit_r11@l(0); \
156 mfcr r10; /* save CR in r10 for now */\
157 mfspr r11,SPRN_SRR3; /* check whether user or kernel */\
158 andi. r11,r11,MSR_PR; \
159 lis r11,critirq_ctx@ha; \
160 tophys(r11,r11); \
161 lwz r11,critirq_ctx@l(r11); \
162 beq 1f; \
163 /* COMING FROM USER MODE */ \
164 mfspr r11,SPRN_SPRG_THREAD; /* if from user, start at top of */\
165 lwz r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
166 1: addi r11,r11,THREAD_SIZE-INT_FRAME_SIZE; /* Alloc an excpt frm */\
167 tophys(r11,r11); \
168 stw r10,_CCR(r11); /* save various registers */\
169 stw r12,GPR12(r11); \
170 stw r9,GPR9(r11); \
171 mflr r10; \
172 stw r10,_LINK(r11); \
173 mfspr r12,SPRN_DEAR; /* save DEAR and ESR in the frame */\
174 stw r12,_DEAR(r11); /* since they may have had stuff */\
175 mfspr r9,SPRN_ESR; /* in them at the point where the */\
176 stw r9,_ESR(r11); /* exception was taken */\
177 mfspr r12,SPRN_SRR2; \
178 stw r1,GPR1(r11); \
179 mfspr r9,SPRN_SRR3; \
180 stw r1,0(r11); \
181 tovirt(r1,r11); \
182 rlwinm r9,r9,0,14,12; /* clear MSR_WE (necessary?) */\
183 stw r0,GPR0(r11); \
184 SAVE_4GPRS(3, r11); \
185 SAVE_2GPRS(7, r11)
187 /*
188 * State at this point:
189 * r9 saved in stack frame, now saved SRR3 & ~MSR_WE
190 * r10 saved in crit_r10 and in stack frame, trashed
191 * r11 saved in crit_r11 and in stack frame,
192 * now phys stack/exception frame pointer
193 * r12 saved in stack frame, now saved SRR2
194 * CR saved in stack frame, CR0.EQ = !SRR3.PR
195 * LR, DEAR, ESR in stack frame
196 * r1 saved in stack frame, now virt stack/excframe pointer
197 * r0, r3-r8 saved in stack frame
198 */
200 /*
201 * Exception vectors.
202 */
203 #define START_EXCEPTION(n, label) \
204 . = n; \
205 label:
207 #define EXCEPTION(n, label, hdlr, xfer) \
208 START_EXCEPTION(n, label); \
209 NORMAL_EXCEPTION_PROLOG; \
210 addi r3,r1,STACK_FRAME_OVERHEAD; \
211 xfer(n, hdlr)
213 #define CRITICAL_EXCEPTION(n, label, hdlr) \
214 START_EXCEPTION(n, label); \
215 CRITICAL_EXCEPTION_PROLOG; \
216 addi r3,r1,STACK_FRAME_OVERHEAD; \
217 EXC_XFER_TEMPLATE(hdlr, n+2, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
218 NOCOPY, crit_transfer_to_handler, \
219 ret_from_crit_exc)
221 #define EXC_XFER_TEMPLATE(hdlr, trap, msr, copyee, tfer, ret) \
222 li r10,trap; \
223 stw r10,_TRAP(r11); \
224 lis r10,msr@h; \
225 ori r10,r10,msr@l; \
226 copyee(r10, r9); \
227 bl tfer; \
228 .long hdlr; \
229 .long ret
231 #define COPY_EE(d, s) rlwimi d,s,0,16,16
232 #define NOCOPY(d, s)
234 #define EXC_XFER_STD(n, hdlr) \
235 EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, NOCOPY, transfer_to_handler_full, \
236 ret_from_except_full)
238 #define EXC_XFER_LITE(n, hdlr) \
239 EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, NOCOPY, transfer_to_handler, \
240 ret_from_except)
242 #define EXC_XFER_EE(n, hdlr) \
243 EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, COPY_EE, transfer_to_handler_full, \
244 ret_from_except_full)
246 #define EXC_XFER_EE_LITE(n, hdlr) \
247 EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, COPY_EE, transfer_to_handler, \
248 ret_from_except)
251 /*
252 * 0x0100 - Critical Interrupt Exception
253 */
254 CRITICAL_EXCEPTION(0x0100, CriticalInterrupt, unknown_exception)
256 /*
257 * 0x0200 - Machine Check Exception
258 */
259 CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception)
261 /*
262 * 0x0300 - Data Storage Exception
263 * This happens for just a few reasons. U0 set (but we don't do that),
264 * or zone protection fault (user violation, write to protected page).
265 * If this is just an update of modified status, we do that quickly
266 * and exit. Otherwise, we call heavywight functions to do the work.
267 */
268 START_EXCEPTION(0x0300, DataStorage)
269 mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */
270 mtspr SPRN_SPRG_SCRATCH1, r11
271 #ifdef CONFIG_403GCX
272 stw r12, 0(r0)
273 stw r9, 4(r0)
274 mfcr r11
275 mfspr r12, SPRN_PID
276 stw r11, 8(r0)
277 stw r12, 12(r0)
278 #else
279 mtspr SPRN_SPRG_SCRATCH3, r12
280 mtspr SPRN_SPRG_SCRATCH4, r9
281 mfcr r11
282 mfspr r12, SPRN_PID
283 mtspr SPRN_SPRG_SCRATCH6, r11
284 mtspr SPRN_SPRG_SCRATCH5, r12
285 #endif
287 /* First, check if it was a zone fault (which means a user
288 * tried to access a kernel or read-protected page - always
289 * a SEGV). All other faults here must be stores, so no
290 * need to check ESR_DST as well. */
291 mfspr r10, SPRN_ESR
292 andis. r10, r10, ESR_DIZ@h
293 bne 2f
295 mfspr r10, SPRN_DEAR /* Get faulting address */
297 /* If we are faulting a kernel address, we have to use the
298 * kernel page tables.
299 */
300 lis r11, PAGE_OFFSET@h
301 cmplw r10, r11
302 blt+ 3f
303 lis r11, swapper_pg_dir@h
304 ori r11, r11, swapper_pg_dir@l
305 li r9, 0
306 mtspr SPRN_PID, r9 /* TLB will have 0 TID */
307 b 4f
309 /* Get the PGD for the current thread.
310 */
311 3:
312 mfspr r11,SPRN_SPRG_THREAD
313 lwz r11,PGDIR(r11)
314 4:
315 tophys(r11, r11)
316 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
317 lwz r11, 0(r11) /* Get L1 entry */
318 rlwinm. r12, r11, 0, 0, 19 /* Extract L2 (pte) base address */
319 beq 2f /* Bail if no table */
321 rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */
322 lwz r11, 0(r12) /* Get Linux PTE */
324 andi. r9, r11, _PAGE_RW /* Is it writeable? */
325 beq 2f /* Bail if not */
327 /* Update 'changed'.
328 */
329 ori r11, r11, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
330 stw r11, 0(r12) /* Update Linux page table */
332 /* Most of the Linux PTE is ready to load into the TLB LO.
333 * We set ZSEL, where only the LS-bit determines user access.
334 * We set execute, because we don't have the granularity to
335 * properly set this at the page level (Linux problem).
336 * If shared is set, we cause a zero PID->TID load.
337 * Many of these bits are software only. Bits we don't set
338 * here we (properly should) assume have the appropriate value.
339 */
340 li r12, 0x0ce2
341 andc r11, r11, r12 /* Make sure 20, 21 are zero */
343 /* find the TLB index that caused the fault. It has to be here.
344 */
345 tlbsx r9, 0, r10
347 tlbwe r11, r9, TLB_DATA /* Load TLB LO */
349 /* Done...restore registers and get out of here.
350 */
351 #ifdef CONFIG_403GCX
352 lwz r12, 12(r0)
353 lwz r11, 8(r0)
354 mtspr SPRN_PID, r12
355 mtcr r11
356 lwz r9, 4(r0)
357 lwz r12, 0(r0)
358 #else
359 mfspr r12, SPRN_SPRG_SCRATCH5
360 mfspr r11, SPRN_SPRG_SCRATCH6
361 mtspr SPRN_PID, r12
362 mtcr r11
363 mfspr r9, SPRN_SPRG_SCRATCH4
364 mfspr r12, SPRN_SPRG_SCRATCH3
365 #endif
366 mfspr r11, SPRN_SPRG_SCRATCH1
367 mfspr r10, SPRN_SPRG_SCRATCH0
368 PPC405_ERR77_SYNC
369 rfi /* Should sync shadow TLBs */
370 b . /* prevent prefetch past rfi */
372 2:
373 /* The bailout. Restore registers to pre-exception conditions
374 * and call the heavyweights to help us out.
375 */
376 #ifdef CONFIG_403GCX
377 lwz r12, 12(r0)
378 lwz r11, 8(r0)
379 mtspr SPRN_PID, r12
380 mtcr r11
381 lwz r9, 4(r0)
382 lwz r12, 0(r0)
383 #else
384 mfspr r12, SPRN_SPRG_SCRATCH5
385 mfspr r11, SPRN_SPRG_SCRATCH6
386 mtspr SPRN_PID, r12
387 mtcr r11
388 mfspr r9, SPRN_SPRG_SCRATCH4
389 mfspr r12, SPRN_SPRG_SCRATCH3
390 #endif
391 mfspr r11, SPRN_SPRG_SCRATCH1
392 mfspr r10, SPRN_SPRG_SCRATCH0
393 b DataAccess
395 /*
396 * 0x0400 - Instruction Storage Exception
397 * This is caused by a fetch from non-execute or guarded pages.
398 */
399 START_EXCEPTION(0x0400, InstructionAccess)
400 NORMAL_EXCEPTION_PROLOG
401 mr r4,r12 /* Pass SRR0 as arg2 */
402 li r5,0 /* Pass zero as arg3 */
403 EXC_XFER_EE_LITE(0x400, handle_page_fault)
405 /* 0x0500 - External Interrupt Exception */
406 EXCEPTION(0x0500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
408 /* 0x0600 - Alignment Exception */
409 START_EXCEPTION(0x0600, Alignment)
410 NORMAL_EXCEPTION_PROLOG
411 mfspr r4,SPRN_DEAR /* Grab the DEAR and save it */
412 stw r4,_DEAR(r11)
413 addi r3,r1,STACK_FRAME_OVERHEAD
414 EXC_XFER_EE(0x600, alignment_exception)
416 /* 0x0700 - Program Exception */
417 START_EXCEPTION(0x0700, ProgramCheck)
418 NORMAL_EXCEPTION_PROLOG
419 mfspr r4,SPRN_ESR /* Grab the ESR and save it */
420 stw r4,_ESR(r11)
421 addi r3,r1,STACK_FRAME_OVERHEAD
422 EXC_XFER_STD(0x700, program_check_exception)
424 EXCEPTION(0x0800, Trap_08, unknown_exception, EXC_XFER_EE)
425 EXCEPTION(0x0900, Trap_09, unknown_exception, EXC_XFER_EE)
426 EXCEPTION(0x0A00, Trap_0A, unknown_exception, EXC_XFER_EE)
427 EXCEPTION(0x0B00, Trap_0B, unknown_exception, EXC_XFER_EE)
429 /* 0x0C00 - System Call Exception */
430 START_EXCEPTION(0x0C00, SystemCall)
431 NORMAL_EXCEPTION_PROLOG
432 EXC_XFER_EE_LITE(0xc00, DoSyscall)
434 EXCEPTION(0x0D00, Trap_0D, unknown_exception, EXC_XFER_EE)
435 EXCEPTION(0x0E00, Trap_0E, unknown_exception, EXC_XFER_EE)
436 EXCEPTION(0x0F00, Trap_0F, unknown_exception, EXC_XFER_EE)
438 /* 0x1000 - Programmable Interval Timer (PIT) Exception */
439 START_EXCEPTION(0x1000, Decrementer)
440 NORMAL_EXCEPTION_PROLOG
441 lis r0,TSR_PIS@h
442 mtspr SPRN_TSR,r0 /* Clear the PIT exception */
443 addi r3,r1,STACK_FRAME_OVERHEAD
444 EXC_XFER_LITE(0x1000, timer_interrupt)
446 #if 0
447 /* NOTE:
448 * FIT and WDT handlers are not implemented yet.
449 */
451 /* 0x1010 - Fixed Interval Timer (FIT) Exception
452 */
453 STND_EXCEPTION(0x1010, FITException, unknown_exception)
455 /* 0x1020 - Watchdog Timer (WDT) Exception
456 */
457 #ifdef CONFIG_BOOKE_WDT
458 CRITICAL_EXCEPTION(0x1020, WDTException, WatchdogException)
459 #else
460 CRITICAL_EXCEPTION(0x1020, WDTException, unknown_exception)
461 #endif
462 #endif
464 /* 0x1100 - Data TLB Miss Exception
465 * As the name implies, translation is not in the MMU, so search the
466 * page tables and fix it. The only purpose of this function is to
467 * load TLB entries from the page table if they exist.
468 */
469 START_EXCEPTION(0x1100, DTLBMiss)
470 mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */
471 mtspr SPRN_SPRG_SCRATCH1, r11
472 #ifdef CONFIG_403GCX
473 stw r12, 0(r0)
474 stw r9, 4(r0)
475 mfcr r11
476 mfspr r12, SPRN_PID
477 stw r11, 8(r0)
478 stw r12, 12(r0)
479 #else
480 mtspr SPRN_SPRG_SCRATCH3, r12
481 mtspr SPRN_SPRG_SCRATCH4, r9
482 mfcr r11
483 mfspr r12, SPRN_PID
484 mtspr SPRN_SPRG_SCRATCH6, r11
485 mtspr SPRN_SPRG_SCRATCH5, r12
486 #endif
487 mfspr r10, SPRN_DEAR /* Get faulting address */
489 /* If we are faulting a kernel address, we have to use the
490 * kernel page tables.
491 */
492 lis r11, PAGE_OFFSET@h
493 cmplw r10, r11
494 blt+ 3f
495 lis r11, swapper_pg_dir@h
496 ori r11, r11, swapper_pg_dir@l
497 li r9, 0
498 mtspr SPRN_PID, r9 /* TLB will have 0 TID */
499 b 4f
501 /* Get the PGD for the current thread.
502 */
503 3:
504 mfspr r11,SPRN_SPRG_THREAD
505 lwz r11,PGDIR(r11)
506 4:
507 tophys(r11, r11)
508 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
509 lwz r12, 0(r11) /* Get L1 entry */
510 andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */
511 beq 2f /* Bail if no table */
513 rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */
514 lwz r11, 0(r12) /* Get Linux PTE */
515 andi. r9, r11, _PAGE_PRESENT
516 beq 5f
518 ori r11, r11, _PAGE_ACCESSED
519 stw r11, 0(r12)
521 /* Create TLB tag. This is the faulting address plus a static
522 * set of bits. These are size, valid, E, U0.
523 */
524 li r12, 0x00c0
525 rlwimi r10, r12, 0, 20, 31
527 b finish_tlb_load
529 2: /* Check for possible large-page pmd entry */
530 rlwinm. r9, r12, 2, 22, 24
531 beq 5f
533 /* Create TLB tag. This is the faulting address, plus a static
534 * set of bits (valid, E, U0) plus the size from the PMD.
535 */
536 ori r9, r9, 0x40
537 rlwimi r10, r9, 0, 20, 31
538 mr r11, r12
540 b finish_tlb_load
542 5:
543 /* The bailout. Restore registers to pre-exception conditions
544 * and call the heavyweights to help us out.
545 */
546 #ifdef CONFIG_403GCX
547 lwz r12, 12(r0)
548 lwz r11, 8(r0)
549 mtspr SPRN_PID, r12
550 mtcr r11
551 lwz r9, 4(r0)
552 lwz r12, 0(r0)
553 #else
554 mfspr r12, SPRN_SPRG_SCRATCH5
555 mfspr r11, SPRN_SPRG_SCRATCH6
556 mtspr SPRN_PID, r12
557 mtcr r11
558 mfspr r9, SPRN_SPRG_SCRATCH4
559 mfspr r12, SPRN_SPRG_SCRATCH3
560 #endif
561 mfspr r11, SPRN_SPRG_SCRATCH1
562 mfspr r10, SPRN_SPRG_SCRATCH0
563 b DataAccess
565 /* 0x1200 - Instruction TLB Miss Exception
566 * Nearly the same as above, except we get our information from different
567 * registers and bailout to a different point.
568 */
569 START_EXCEPTION(0x1200, ITLBMiss)
570 mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */
571 mtspr SPRN_SPRG_SCRATCH1, r11
572 #ifdef CONFIG_403GCX
573 stw r12, 0(r0)
574 stw r9, 4(r0)
575 mfcr r11
576 mfspr r12, SPRN_PID
577 stw r11, 8(r0)
578 stw r12, 12(r0)
579 #else
580 mtspr SPRN_SPRG_SCRATCH3, r12
581 mtspr SPRN_SPRG_SCRATCH4, r9
582 mfcr r11
583 mfspr r12, SPRN_PID
584 mtspr SPRN_SPRG_SCRATCH6, r11
585 mtspr SPRN_SPRG_SCRATCH5, r12
586 #endif
587 mfspr r10, SPRN_SRR0 /* Get faulting address */
589 /* If we are faulting a kernel address, we have to use the
590 * kernel page tables.
591 */
592 lis r11, PAGE_OFFSET@h
593 cmplw r10, r11
594 blt+ 3f
595 lis r11, swapper_pg_dir@h
596 ori r11, r11, swapper_pg_dir@l
597 li r9, 0
598 mtspr SPRN_PID, r9 /* TLB will have 0 TID */
599 b 4f
601 /* Get the PGD for the current thread.
602 */
603 3:
604 mfspr r11,SPRN_SPRG_THREAD
605 lwz r11,PGDIR(r11)
606 4:
607 tophys(r11, r11)
608 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
609 lwz r12, 0(r11) /* Get L1 entry */
610 andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */
611 beq 2f /* Bail if no table */
613 rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */
614 lwz r11, 0(r12) /* Get Linux PTE */
615 andi. r9, r11, _PAGE_PRESENT
616 beq 5f
618 ori r11, r11, _PAGE_ACCESSED
619 stw r11, 0(r12)
621 /* Create TLB tag. This is the faulting address plus a static
622 * set of bits. These are size, valid, E, U0.
623 */
624 li r12, 0x00c0
625 rlwimi r10, r12, 0, 20, 31
627 b finish_tlb_load
629 2: /* Check for possible large-page pmd entry */
630 rlwinm. r9, r12, 2, 22, 24
631 beq 5f
633 /* Create TLB tag. This is the faulting address, plus a static
634 * set of bits (valid, E, U0) plus the size from the PMD.
635 */
636 ori r9, r9, 0x40
637 rlwimi r10, r9, 0, 20, 31
638 mr r11, r12
640 b finish_tlb_load
642 5:
643 /* The bailout. Restore registers to pre-exception conditions
644 * and call the heavyweights to help us out.
645 */
646 #ifdef CONFIG_403GCX
647 lwz r12, 12(r0)
648 lwz r11, 8(r0)
649 mtspr SPRN_PID, r12
650 mtcr r11
651 lwz r9, 4(r0)
652 lwz r12, 0(r0)
653 #else
654 mfspr r12, SPRN_SPRG_SCRATCH5
655 mfspr r11, SPRN_SPRG_SCRATCH6
656 mtspr SPRN_PID, r12
657 mtcr r11
658 mfspr r9, SPRN_SPRG_SCRATCH4
659 mfspr r12, SPRN_SPRG_SCRATCH3
660 #endif
661 mfspr r11, SPRN_SPRG_SCRATCH1
662 mfspr r10, SPRN_SPRG_SCRATCH0
663 b InstructionAccess
665 EXCEPTION(0x1300, Trap_13, unknown_exception, EXC_XFER_EE)
666 EXCEPTION(0x1400, Trap_14, unknown_exception, EXC_XFER_EE)
667 EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
668 EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
669 #ifdef CONFIG_IBM405_ERR51
670 /* 405GP errata 51 */
671 START_EXCEPTION(0x1700, Trap_17)
672 b DTLBMiss
673 #else
674 EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE)
675 #endif
676 EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_EE)
677 EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_EE)
678 EXCEPTION(0x1A00, Trap_1A, unknown_exception, EXC_XFER_EE)
679 EXCEPTION(0x1B00, Trap_1B, unknown_exception, EXC_XFER_EE)
680 EXCEPTION(0x1C00, Trap_1C, unknown_exception, EXC_XFER_EE)
681 EXCEPTION(0x1D00, Trap_1D, unknown_exception, EXC_XFER_EE)
682 EXCEPTION(0x1E00, Trap_1E, unknown_exception, EXC_XFER_EE)
683 EXCEPTION(0x1F00, Trap_1F, unknown_exception, EXC_XFER_EE)
685 /* Check for a single step debug exception while in an exception
686 * handler before state has been saved. This is to catch the case
687 * where an instruction that we are trying to single step causes
688 * an exception (eg ITLB/DTLB miss) and thus the first instruction of
689 * the exception handler generates a single step debug exception.
690 *
691 * If we get a debug trap on the first instruction of an exception handler,
692 * we reset the MSR_DE in the _exception handler's_ MSR (the debug trap is
693 * a critical exception, so we are using SPRN_CSRR1 to manipulate the MSR).
694 * The exception handler was handling a non-critical interrupt, so it will
695 * save (and later restore) the MSR via SPRN_SRR1, which will still have
696 * the MSR_DE bit set.
697 */
698 /* 0x2000 - Debug Exception */
699 START_EXCEPTION(0x2000, DebugTrap)
700 CRITICAL_EXCEPTION_PROLOG
702 /*
703 * If this is a single step or branch-taken exception in an
704 * exception entry sequence, it was probably meant to apply to
705 * the code where the exception occurred (since exception entry
706 * doesn't turn off DE automatically). We simulate the effect
707 * of turning off DE on entry to an exception handler by turning
708 * off DE in the SRR3 value and clearing the debug status.
709 */
710 mfspr r10,SPRN_DBSR /* check single-step/branch taken */
711 andis. r10,r10,DBSR_IC@h
712 beq+ 2f
714 andi. r10,r9,MSR_IR|MSR_PR /* check supervisor + MMU off */
715 beq 1f /* branch and fix it up */
717 mfspr r10,SPRN_SRR2 /* Faulting instruction address */
718 cmplwi r10,0x2100
719 bgt+ 2f /* address above exception vectors */
721 /* here it looks like we got an inappropriate debug exception. */
722 1: rlwinm r9,r9,0,~MSR_DE /* clear DE in the SRR3 value */
723 lis r10,DBSR_IC@h /* clear the IC event */
724 mtspr SPRN_DBSR,r10
725 /* restore state and get out */
726 lwz r10,_CCR(r11)
727 lwz r0,GPR0(r11)
728 lwz r1,GPR1(r11)
729 mtcrf 0x80,r10
730 mtspr SPRN_SRR2,r12
731 mtspr SPRN_SRR3,r9
732 lwz r9,GPR9(r11)
733 lwz r12,GPR12(r11)
734 lwz r10,crit_r10@l(0)
735 lwz r11,crit_r11@l(0)
736 PPC405_ERR77_SYNC
737 rfci
738 b .
740 /* continue normal handling for a critical exception... */
741 2: mfspr r4,SPRN_DBSR
742 addi r3,r1,STACK_FRAME_OVERHEAD
743 EXC_XFER_TEMPLATE(DebugException, 0x2002, \
744 (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
745 NOCOPY, crit_transfer_to_handler, ret_from_crit_exc)
747 /*
748 * The other Data TLB exceptions bail out to this point
749 * if they can't resolve the lightweight TLB fault.
750 */
751 DataAccess:
752 NORMAL_EXCEPTION_PROLOG
753 mfspr r5,SPRN_ESR /* Grab the ESR, save it, pass arg3 */
754 stw r5,_ESR(r11)
755 mfspr r4,SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */
756 EXC_XFER_EE_LITE(0x300, handle_page_fault)
758 /* Other PowerPC processors, namely those derived from the 6xx-series
759 * have vectors from 0x2100 through 0x2F00 defined, but marked as reserved.
760 * However, for the 4xx-series processors these are neither defined nor
761 * reserved.
762 */
764 /* Damn, I came up one instruction too many to fit into the
765 * exception space :-). Both the instruction and data TLB
766 * miss get to this point to load the TLB.
767 * r10 - TLB_TAG value
768 * r11 - Linux PTE
769 * r12, r9 - avilable to use
770 * PID - loaded with proper value when we get here
771 * Upon exit, we reload everything and RFI.
772 * Actually, it will fit now, but oh well.....a common place
773 * to load the TLB.
774 */
775 tlb_4xx_index:
776 .long 0
777 finish_tlb_load:
778 /* load the next available TLB index.
779 */
780 lwz r9, tlb_4xx_index@l(0)
781 addi r9, r9, 1
782 andi. r9, r9, (PPC40X_TLB_SIZE-1)
783 stw r9, tlb_4xx_index@l(0)
785 6:
786 /*
787 * Clear out the software-only bits in the PTE to generate the
788 * TLB_DATA value. These are the bottom 2 bits of the RPM, the
789 * top 3 bits of the zone field, and M.
790 */
791 li r12, 0x0ce2
792 andc r11, r11, r12
794 tlbwe r11, r9, TLB_DATA /* Load TLB LO */
795 tlbwe r10, r9, TLB_TAG /* Load TLB HI */
797 /* Done...restore registers and get out of here.
798 */
799 #ifdef CONFIG_403GCX
800 lwz r12, 12(r0)
801 lwz r11, 8(r0)
802 mtspr SPRN_PID, r12
803 mtcr r11
804 lwz r9, 4(r0)
805 lwz r12, 0(r0)
806 #else
807 mfspr r12, SPRN_SPRG_SCRATCH5
808 mfspr r11, SPRN_SPRG_SCRATCH6
809 mtspr SPRN_PID, r12
810 mtcr r11
811 mfspr r9, SPRN_SPRG_SCRATCH4
812 mfspr r12, SPRN_SPRG_SCRATCH3
813 #endif
814 mfspr r11, SPRN_SPRG_SCRATCH1
815 mfspr r10, SPRN_SPRG_SCRATCH0
816 PPC405_ERR77_SYNC
817 rfi /* Should sync shadow TLBs */
818 b . /* prevent prefetch past rfi */
820 /* extern void giveup_fpu(struct task_struct *prev)
821 *
822 * The PowerPC 4xx family of processors do not have an FPU, so this just
823 * returns.
824 */
825 _ENTRY(giveup_fpu)
826 blr
828 /* This is where the main kernel code starts.
829 */
830 start_here:
832 /* ptr to current */
833 lis r2,init_task@h
834 ori r2,r2,init_task@l
836 /* ptr to phys current thread */
837 tophys(r4,r2)
838 addi r4,r4,THREAD /* init task's THREAD */
839 mtspr SPRN_SPRG_THREAD,r4
841 /* stack */
842 lis r1,init_thread_union@ha
843 addi r1,r1,init_thread_union@l
844 li r0,0
845 stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
847 bl early_init /* We have to do this with MMU on */
849 /*
850 * Decide what sort of machine this is and initialize the MMU.
851 */
852 mr r3,r31
853 mr r4,r30
854 mr r5,r29
855 mr r6,r28
856 mr r7,r27
857 bl machine_init
858 bl MMU_init
860 /* Go back to running unmapped so we can load up new values
861 * and change to using our exception vectors.
862 * On the 4xx, all we have to do is invalidate the TLB to clear
863 * the old 16M byte TLB mappings.
864 */
865 lis r4,2f@h
866 ori r4,r4,2f@l
867 tophys(r4,r4)
868 lis r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@h
869 ori r3,r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@l
870 mtspr SPRN_SRR0,r4
871 mtspr SPRN_SRR1,r3
872 rfi
873 b . /* prevent prefetch past rfi */
875 /* Load up the kernel context */
876 2:
877 sync /* Flush to memory before changing TLB */
878 tlbia
879 isync /* Flush shadow TLBs */
881 /* set up the PTE pointers for the Abatron bdiGDB.
882 */
883 lis r6, swapper_pg_dir@h
884 ori r6, r6, swapper_pg_dir@l
885 lis r5, abatron_pteptrs@h
886 ori r5, r5, abatron_pteptrs@l
887 stw r5, 0xf0(r0) /* Must match your Abatron config file */
888 tophys(r5,r5)
889 stw r6, 0(r5)
891 /* Now turn on the MMU for real! */
892 lis r4,MSR_KERNEL@h
893 ori r4,r4,MSR_KERNEL@l
894 lis r3,start_kernel@h
895 ori r3,r3,start_kernel@l
896 mtspr SPRN_SRR0,r3
897 mtspr SPRN_SRR1,r4
898 rfi /* enable MMU and jump to start_kernel */
899 b . /* prevent prefetch past rfi */
901 /* Set up the initial MMU state so we can do the first level of
902 * kernel initialization. This maps the first 16 MBytes of memory 1:1
903 * virtual to physical and more importantly sets the cache mode.
904 */
905 initial_mmu:
906 tlbia /* Invalidate all TLB entries */
907 isync
909 /* We should still be executing code at physical address 0x0000xxxx
910 * at this point. However, start_here is at virtual address
911 * 0xC000xxxx. So, set up a TLB mapping to cover this once
912 * translation is enabled.
913 */
915 lis r3,KERNELBASE@h /* Load the kernel virtual address */
916 ori r3,r3,KERNELBASE@l
917 tophys(r4,r3) /* Load the kernel physical address */
919 iccci r0,r3 /* Invalidate the i-cache before use */
921 /* Load the kernel PID.
922 */
923 li r0,0
924 mtspr SPRN_PID,r0
925 sync
927 /* Configure and load one entry into TLB slots 63 */
928 clrrwi r4,r4,10 /* Mask off the real page number */
929 ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */
931 clrrwi r3,r3,10 /* Mask off the effective page number */
932 ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M))
934 li r0,63 /* TLB slot 63 */
936 tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */
937 tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */
939 #if defined(CONFIG_SERIAL_TEXT_DEBUG) && defined(SERIAL_DEBUG_IO_BASE)
941 /* Load a TLB entry for the UART, so that ppc4xx_progress() can use
942 * the UARTs nice and early. We use a 4k real==virtual mapping. */
944 lis r3,SERIAL_DEBUG_IO_BASE@h
945 ori r3,r3,SERIAL_DEBUG_IO_BASE@l
946 mr r4,r3
947 clrrwi r4,r4,12
948 ori r4,r4,(TLB_WR|TLB_I|TLB_M|TLB_G)
950 clrrwi r3,r3,12
951 ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_4K))
953 li r0,0 /* TLB slot 0 */
954 tlbwe r4,r0,TLB_DATA
955 tlbwe r3,r0,TLB_TAG
956 #endif /* CONFIG_SERIAL_DEBUG_TEXT && SERIAL_DEBUG_IO_BASE */
958 isync
960 /* Establish the exception vector base
961 */
962 lis r4,KERNELBASE@h /* EVPR only uses the high 16-bits */
963 tophys(r0,r4) /* Use the physical address */
964 mtspr SPRN_EVPR,r0
966 blr
968 _GLOBAL(abort)
969 mfspr r13,SPRN_DBCR0
970 oris r13,r13,DBCR0_RST_SYSTEM@h
971 mtspr SPRN_DBCR0,r13
973 _GLOBAL(set_context)
975 #ifdef CONFIG_BDI_SWITCH
976 /* Context switch the PTE pointer for the Abatron BDI2000.
977 * The PGDIR is the second parameter.
978 */
979 lis r5, KERNELBASE@h
980 lwz r5, 0xf0(r5)
981 stw r4, 0x4(r5)
982 #endif
983 sync
984 mtspr SPRN_PID,r3
985 isync /* Need an isync to flush shadow */
986 /* TLBs after changing PID */
987 blr
989 /* We put a few things here that have to be page-aligned. This stuff
990 * goes at the beginning of the data segment, which is page-aligned.
991 */
992 .data
993 .align 12
994 .globl sdata
995 sdata:
996 .globl empty_zero_page
997 empty_zero_page:
998 .space 4096
999 .globl swapper_pg_dir
1000 swapper_pg_dir:
1001 .space PGD_TABLE_SIZE
1003 /* Room for two PTE pointers, usually the kernel and current user pointers
1004 * to their respective root page table.
1005 */
1006 abatron_pteptrs:
1007 .space 8