| blob | 7d7d8635227ac76bcd054b3fd04248ec90127c9d |
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 mr r31,r3 /* save device tree ptr */
63 /* We have to turn on the MMU right away so we get cache modes
64 * set correctly.
65 */
66 bl initial_mmu
68 /* We now have the lower 16 Meg mapped into TLB entries, and the caches
69 * ready to work.
70 */
71 turn_on_mmu:
72 lis r0,MSR_KERNEL@h
73 ori r0,r0,MSR_KERNEL@l
74 mtspr SPRN_SRR1,r0
75 lis r0,start_here@h
76 ori r0,r0,start_here@l
77 mtspr SPRN_SRR0,r0
78 SYNC
79 rfi /* enables MMU */
80 b . /* prevent prefetch past rfi */
82 /*
83 * This area is used for temporarily saving registers during the
84 * critical exception prolog.
85 */
86 . = 0xc0
87 crit_save:
88 _ENTRY(crit_r10)
89 .space 4
90 _ENTRY(crit_r11)
91 .space 4
92 _ENTRY(crit_srr0)
93 .space 4
94 _ENTRY(crit_srr1)
95 .space 4
96 _ENTRY(saved_ksp_limit)
97 .space 4
99 /*
100 * Exception vector entry code. This code runs with address translation
101 * turned off (i.e. using physical addresses). We assume SPRG_THREAD has
102 * the 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_SPRG_SCRATCH0,r10; /* save two registers to work with */\
109 mtspr SPRN_SPRG_SCRATCH1,r11; \
110 mtspr SPRN_SPRG_SCRATCH2,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_SPRG_THREAD; /* 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; \
118 1: 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_SPRG_SCRATCH0; \
124 stw r10,GPR10(r11); \
125 mfspr r12,SPRN_SPRG_SCRATCH1; \
126 stw r12,GPR11(r11); \
127 mflr r10; \
128 stw r10,_LINK(r11); \
129 mfspr r10,SPRN_SPRG_SCRATCH2; \
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)
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,critirq_ctx@ha; \
154 tophys(r11,r11); \
155 lwz r11,critirq_ctx@l(r11); \
156 beq 1f; \
157 /* COMING FROM USER MODE */ \
158 mfspr r11,SPRN_SPRG_THREAD; /* if from user, start at top of */\
159 lwz r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
160 1: addi r11,r11,THREAD_SIZE-INT_FRAME_SIZE; /* Alloc an excpt frm */\
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)
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 */
194 /*
195 * Exception vectors.
196 */
197 #define START_EXCEPTION(n, label) \
198 . = n; \
199 label:
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)
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)
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
225 #define COPY_EE(d, s) rlwimi d,s,0,16,16
226 #define NOCOPY(d, s)
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)
232 #define EXC_XFER_LITE(n, hdlr) \
233 EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, NOCOPY, transfer_to_handler, \
234 ret_from_except)
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)
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)
245 /*
246 * 0x0100 - Critical Interrupt Exception
247 */
248 CRITICAL_EXCEPTION(0x0100, CriticalInterrupt, unknown_exception)
250 /*
251 * 0x0200 - Machine Check Exception
252 */
253 CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception)
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_SPRG_SCRATCH0, r10 /* Save some working registers */
264 mtspr SPRN_SPRG_SCRATCH1, 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_SPRG_SCRATCH3, r12
274 mtspr SPRN_SPRG_SCRATCH4, r9
275 mfcr r11
276 mfspr r12, SPRN_PID
277 mtspr SPRN_SPRG_SCRATCH6, r11
278 mtspr SPRN_SPRG_SCRATCH5, r12
279 #endif
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
289 mfspr r10, SPRN_DEAR /* Get faulting address */
291 /* If we are faulting a kernel address, we have to use the
292 * kernel page tables.
293 */
294 lis r11, PAGE_OFFSET@h
295 cmplw r10, r11
296 blt+ 3f
297 lis r11, swapper_pg_dir@h
298 ori r11, r11, swapper_pg_dir@l
299 li r9, 0
300 mtspr SPRN_PID, r9 /* TLB will have 0 TID */
301 b 4f
303 /* Get the PGD for the current thread.
304 */
305 3:
306 mfspr r11,SPRN_SPRG_THREAD
307 lwz r11,PGDIR(r11)
308 4:
309 tophys(r11, r11)
310 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
311 lwz r11, 0(r11) /* Get L1 entry */
312 rlwinm. r12, r11, 0, 0, 19 /* Extract L2 (pte) base address */
313 beq 2f /* Bail if no table */
315 rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */
316 lwz r11, 0(r12) /* Get Linux PTE */
318 andi. r9, r11, _PAGE_RW /* Is it writeable? */
319 beq 2f /* Bail if not */
321 /* Update 'changed'.
322 */
323 ori r11, r11, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
324 stw r11, 0(r12) /* Update Linux page table */
326 /* Most of the Linux PTE is ready to load into the TLB LO.
327 * We set ZSEL, where only the LS-bit determines user access.
328 * We set execute, because we don't have the granularity to
329 * properly set this at the page level (Linux problem).
330 * If shared is set, we cause a zero PID->TID load.
331 * Many of these bits are software only. Bits we don't set
332 * here we (properly should) assume have the appropriate value.
333 */
334 li r12, 0x0ce2
335 andc r11, r11, r12 /* Make sure 20, 21 are zero */
337 /* find the TLB index that caused the fault. It has to be here.
338 */
339 tlbsx r9, 0, r10
341 tlbwe r11, r9, TLB_DATA /* Load TLB LO */
343 /* Done...restore registers and get out of here.
344 */
345 #ifdef CONFIG_403GCX
346 lwz r12, 12(r0)
347 lwz r11, 8(r0)
348 mtspr SPRN_PID, r12
349 mtcr r11
350 lwz r9, 4(r0)
351 lwz r12, 0(r0)
352 #else
353 mfspr r12, SPRN_SPRG_SCRATCH5
354 mfspr r11, SPRN_SPRG_SCRATCH6
355 mtspr SPRN_PID, r12
356 mtcr r11
357 mfspr r9, SPRN_SPRG_SCRATCH4
358 mfspr r12, SPRN_SPRG_SCRATCH3
359 #endif
360 mfspr r11, SPRN_SPRG_SCRATCH1
361 mfspr r10, SPRN_SPRG_SCRATCH0
362 PPC405_ERR77_SYNC
363 rfi /* Should sync shadow TLBs */
364 b . /* prevent prefetch past rfi */
366 2:
367 /* The bailout. Restore registers to pre-exception conditions
368 * and call the heavyweights to help us out.
369 */
370 #ifdef CONFIG_403GCX
371 lwz r12, 12(r0)
372 lwz r11, 8(r0)
373 mtspr SPRN_PID, r12
374 mtcr r11
375 lwz r9, 4(r0)
376 lwz r12, 0(r0)
377 #else
378 mfspr r12, SPRN_SPRG_SCRATCH5
379 mfspr r11, SPRN_SPRG_SCRATCH6
380 mtspr SPRN_PID, r12
381 mtcr r11
382 mfspr r9, SPRN_SPRG_SCRATCH4
383 mfspr r12, SPRN_SPRG_SCRATCH3
384 #endif
385 mfspr r11, SPRN_SPRG_SCRATCH1
386 mfspr r10, SPRN_SPRG_SCRATCH0
387 b DataAccess
389 /*
390 * 0x0400 - Instruction Storage Exception
391 * This is caused by a fetch from non-execute or guarded pages.
392 */
393 START_EXCEPTION(0x0400, InstructionAccess)
394 NORMAL_EXCEPTION_PROLOG
395 mr r4,r12 /* Pass SRR0 as arg2 */
396 li r5,0 /* Pass zero as arg3 */
397 EXC_XFER_LITE(0x400, handle_page_fault)
399 /* 0x0500 - External Interrupt Exception */
400 EXCEPTION(0x0500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
402 /* 0x0600 - Alignment Exception */
403 START_EXCEPTION(0x0600, Alignment)
404 NORMAL_EXCEPTION_PROLOG
405 mfspr r4,SPRN_DEAR /* Grab the DEAR and save it */
406 stw r4,_DEAR(r11)
407 addi r3,r1,STACK_FRAME_OVERHEAD
408 EXC_XFER_EE(0x600, alignment_exception)
410 /* 0x0700 - Program Exception */
411 START_EXCEPTION(0x0700, ProgramCheck)
412 NORMAL_EXCEPTION_PROLOG
413 mfspr r4,SPRN_ESR /* Grab the ESR and save it */
414 stw r4,_ESR(r11)
415 addi r3,r1,STACK_FRAME_OVERHEAD
416 EXC_XFER_STD(0x700, program_check_exception)
418 EXCEPTION(0x0800, Trap_08, unknown_exception, EXC_XFER_EE)
419 EXCEPTION(0x0900, Trap_09, unknown_exception, EXC_XFER_EE)
420 EXCEPTION(0x0A00, Trap_0A, unknown_exception, EXC_XFER_EE)
421 EXCEPTION(0x0B00, Trap_0B, unknown_exception, EXC_XFER_EE)
423 /* 0x0C00 - System Call Exception */
424 START_EXCEPTION(0x0C00, SystemCall)
425 NORMAL_EXCEPTION_PROLOG
426 EXC_XFER_EE_LITE(0xc00, DoSyscall)
428 EXCEPTION(0x0D00, Trap_0D, unknown_exception, EXC_XFER_EE)
429 EXCEPTION(0x0E00, Trap_0E, unknown_exception, EXC_XFER_EE)
430 EXCEPTION(0x0F00, Trap_0F, unknown_exception, EXC_XFER_EE)
432 /* 0x1000 - Programmable Interval Timer (PIT) Exception */
433 . = 0x1000
434 b Decrementer
436 /* 0x1010 - Fixed Interval Timer (FIT) Exception
437 */
438 . = 0x1010
439 b FITException
441 /* 0x1020 - Watchdog Timer (WDT) Exception
442 */
443 . = 0x1020
444 b WDTException
446 /* 0x1100 - Data TLB Miss Exception
447 * As the name implies, translation is not in the MMU, so search the
448 * page tables and fix it. The only purpose of this function is to
449 * load TLB entries from the page table if they exist.
450 */
451 START_EXCEPTION(0x1100, DTLBMiss)
452 mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */
453 mtspr SPRN_SPRG_SCRATCH1, r11
454 #ifdef CONFIG_403GCX
455 stw r12, 0(r0)
456 stw r9, 4(r0)
457 mfcr r11
458 mfspr r12, SPRN_PID
459 stw r11, 8(r0)
460 stw r12, 12(r0)
461 #else
462 mtspr SPRN_SPRG_SCRATCH3, r12
463 mtspr SPRN_SPRG_SCRATCH4, r9
464 mfcr r11
465 mfspr r12, SPRN_PID
466 mtspr SPRN_SPRG_SCRATCH6, r11
467 mtspr SPRN_SPRG_SCRATCH5, r12
468 #endif
469 mfspr r10, SPRN_DEAR /* Get faulting address */
471 /* If we are faulting a kernel address, we have to use the
472 * kernel page tables.
473 */
474 lis r11, PAGE_OFFSET@h
475 cmplw r10, r11
476 blt+ 3f
477 lis r11, swapper_pg_dir@h
478 ori r11, r11, swapper_pg_dir@l
479 li r9, 0
480 mtspr SPRN_PID, r9 /* TLB will have 0 TID */
481 b 4f
483 /* Get the PGD for the current thread.
484 */
485 3:
486 mfspr r11,SPRN_SPRG_THREAD
487 lwz r11,PGDIR(r11)
488 4:
489 tophys(r11, r11)
490 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
491 lwz r12, 0(r11) /* Get L1 entry */
492 andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */
493 beq 2f /* Bail if no table */
495 rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */
496 lwz r11, 0(r12) /* Get Linux PTE */
497 andi. r9, r11, _PAGE_PRESENT
498 beq 5f
500 ori r11, r11, _PAGE_ACCESSED
501 stw r11, 0(r12)
503 /* Create TLB tag. This is the faulting address plus a static
504 * set of bits. These are size, valid, E, U0.
505 */
506 li r12, 0x00c0
507 rlwimi r10, r12, 0, 20, 31
509 b finish_tlb_load
511 2: /* Check for possible large-page pmd entry */
512 rlwinm. r9, r12, 2, 22, 24
513 beq 5f
515 /* Create TLB tag. This is the faulting address, plus a static
516 * set of bits (valid, E, U0) plus the size from the PMD.
517 */
518 ori r9, r9, 0x40
519 rlwimi r10, r9, 0, 20, 31
520 mr r11, r12
522 b finish_tlb_load
524 5:
525 /* The bailout. Restore registers to pre-exception conditions
526 * and call the heavyweights to help us out.
527 */
528 #ifdef CONFIG_403GCX
529 lwz r12, 12(r0)
530 lwz r11, 8(r0)
531 mtspr SPRN_PID, r12
532 mtcr r11
533 lwz r9, 4(r0)
534 lwz r12, 0(r0)
535 #else
536 mfspr r12, SPRN_SPRG_SCRATCH5
537 mfspr r11, SPRN_SPRG_SCRATCH6
538 mtspr SPRN_PID, r12
539 mtcr r11
540 mfspr r9, SPRN_SPRG_SCRATCH4
541 mfspr r12, SPRN_SPRG_SCRATCH3
542 #endif
543 mfspr r11, SPRN_SPRG_SCRATCH1
544 mfspr r10, SPRN_SPRG_SCRATCH0
545 b DataAccess
547 /* 0x1200 - Instruction TLB Miss Exception
548 * Nearly the same as above, except we get our information from different
549 * registers and bailout to a different point.
550 */
551 START_EXCEPTION(0x1200, ITLBMiss)
552 mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */
553 mtspr SPRN_SPRG_SCRATCH1, r11
554 #ifdef CONFIG_403GCX
555 stw r12, 0(r0)
556 stw r9, 4(r0)
557 mfcr r11
558 mfspr r12, SPRN_PID
559 stw r11, 8(r0)
560 stw r12, 12(r0)
561 #else
562 mtspr SPRN_SPRG_SCRATCH3, r12
563 mtspr SPRN_SPRG_SCRATCH4, r9
564 mfcr r11
565 mfspr r12, SPRN_PID
566 mtspr SPRN_SPRG_SCRATCH6, r11
567 mtspr SPRN_SPRG_SCRATCH5, r12
568 #endif
569 mfspr r10, SPRN_SRR0 /* Get faulting address */
571 /* If we are faulting a kernel address, we have to use the
572 * kernel page tables.
573 */
574 lis r11, PAGE_OFFSET@h
575 cmplw r10, r11
576 blt+ 3f
577 lis r11, swapper_pg_dir@h
578 ori r11, r11, swapper_pg_dir@l
579 li r9, 0
580 mtspr SPRN_PID, r9 /* TLB will have 0 TID */
581 b 4f
583 /* Get the PGD for the current thread.
584 */
585 3:
586 mfspr r11,SPRN_SPRG_THREAD
587 lwz r11,PGDIR(r11)
588 4:
589 tophys(r11, r11)
590 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
591 lwz r12, 0(r11) /* Get L1 entry */
592 andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */
593 beq 2f /* Bail if no table */
595 rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */
596 lwz r11, 0(r12) /* Get Linux PTE */
597 andi. r9, r11, _PAGE_PRESENT
598 beq 5f
600 ori r11, r11, _PAGE_ACCESSED
601 stw r11, 0(r12)
603 /* Create TLB tag. This is the faulting address plus a static
604 * set of bits. These are size, valid, E, U0.
605 */
606 li r12, 0x00c0
607 rlwimi r10, r12, 0, 20, 31
609 b finish_tlb_load
611 2: /* Check for possible large-page pmd entry */
612 rlwinm. r9, r12, 2, 22, 24
613 beq 5f
615 /* Create TLB tag. This is the faulting address, plus a static
616 * set of bits (valid, E, U0) plus the size from the PMD.
617 */
618 ori r9, r9, 0x40
619 rlwimi r10, r9, 0, 20, 31
620 mr r11, r12
622 b finish_tlb_load
624 5:
625 /* The bailout. Restore registers to pre-exception conditions
626 * and call the heavyweights to help us out.
627 */
628 #ifdef CONFIG_403GCX
629 lwz r12, 12(r0)
630 lwz r11, 8(r0)
631 mtspr SPRN_PID, r12
632 mtcr r11
633 lwz r9, 4(r0)
634 lwz r12, 0(r0)
635 #else
636 mfspr r12, SPRN_SPRG_SCRATCH5
637 mfspr r11, SPRN_SPRG_SCRATCH6
638 mtspr SPRN_PID, r12
639 mtcr r11
640 mfspr r9, SPRN_SPRG_SCRATCH4
641 mfspr r12, SPRN_SPRG_SCRATCH3
642 #endif
643 mfspr r11, SPRN_SPRG_SCRATCH1
644 mfspr r10, SPRN_SPRG_SCRATCH0
645 b InstructionAccess
647 EXCEPTION(0x1300, Trap_13, unknown_exception, EXC_XFER_EE)
648 EXCEPTION(0x1400, Trap_14, unknown_exception, EXC_XFER_EE)
649 EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
650 EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
651 #ifdef CONFIG_IBM405_ERR51
652 /* 405GP errata 51 */
653 START_EXCEPTION(0x1700, Trap_17)
654 b DTLBMiss
655 #else
656 EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE)
657 #endif
658 EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_EE)
659 EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_EE)
660 EXCEPTION(0x1A00, Trap_1A, unknown_exception, EXC_XFER_EE)
661 EXCEPTION(0x1B00, Trap_1B, unknown_exception, EXC_XFER_EE)
662 EXCEPTION(0x1C00, Trap_1C, unknown_exception, EXC_XFER_EE)
663 EXCEPTION(0x1D00, Trap_1D, unknown_exception, EXC_XFER_EE)
664 EXCEPTION(0x1E00, Trap_1E, unknown_exception, EXC_XFER_EE)
665 EXCEPTION(0x1F00, Trap_1F, unknown_exception, EXC_XFER_EE)
667 /* Check for a single step debug exception while in an exception
668 * handler before state has been saved. This is to catch the case
669 * where an instruction that we are trying to single step causes
670 * an exception (eg ITLB/DTLB miss) and thus the first instruction of
671 * the exception handler generates a single step debug exception.
672 *
673 * If we get a debug trap on the first instruction of an exception handler,
674 * we reset the MSR_DE in the _exception handler's_ MSR (the debug trap is
675 * a critical exception, so we are using SPRN_CSRR1 to manipulate the MSR).
676 * The exception handler was handling a non-critical interrupt, so it will
677 * save (and later restore) the MSR via SPRN_SRR1, which will still have
678 * the MSR_DE bit set.
679 */
680 /* 0x2000 - Debug Exception */
681 START_EXCEPTION(0x2000, DebugTrap)
682 CRITICAL_EXCEPTION_PROLOG
684 /*
685 * If this is a single step or branch-taken exception in an
686 * exception entry sequence, it was probably meant to apply to
687 * the code where the exception occurred (since exception entry
688 * doesn't turn off DE automatically). We simulate the effect
689 * of turning off DE on entry to an exception handler by turning
690 * off DE in the SRR3 value and clearing the debug status.
691 */
692 mfspr r10,SPRN_DBSR /* check single-step/branch taken */
693 andis. r10,r10,DBSR_IC@h
694 beq+ 2f
696 andi. r10,r9,MSR_IR|MSR_PR /* check supervisor + MMU off */
697 beq 1f /* branch and fix it up */
699 mfspr r10,SPRN_SRR2 /* Faulting instruction address */
700 cmplwi r10,0x2100
701 bgt+ 2f /* address above exception vectors */
703 /* here it looks like we got an inappropriate debug exception. */
704 1: rlwinm r9,r9,0,~MSR_DE /* clear DE in the SRR3 value */
705 lis r10,DBSR_IC@h /* clear the IC event */
706 mtspr SPRN_DBSR,r10
707 /* restore state and get out */
708 lwz r10,_CCR(r11)
709 lwz r0,GPR0(r11)
710 lwz r1,GPR1(r11)
711 mtcrf 0x80,r10
712 mtspr SPRN_SRR2,r12
713 mtspr SPRN_SRR3,r9
714 lwz r9,GPR9(r11)
715 lwz r12,GPR12(r11)
716 lwz r10,crit_r10@l(0)
717 lwz r11,crit_r11@l(0)
718 PPC405_ERR77_SYNC
719 rfci
720 b .
722 /* continue normal handling for a critical exception... */
723 2: mfspr r4,SPRN_DBSR
724 addi r3,r1,STACK_FRAME_OVERHEAD
725 EXC_XFER_TEMPLATE(DebugException, 0x2002, \
726 (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
727 NOCOPY, crit_transfer_to_handler, ret_from_crit_exc)
729 /* Programmable Interval Timer (PIT) Exception. (from 0x1000) */
730 Decrementer:
731 NORMAL_EXCEPTION_PROLOG
732 lis r0,TSR_PIS@h
733 mtspr SPRN_TSR,r0 /* Clear the PIT exception */
734 addi r3,r1,STACK_FRAME_OVERHEAD
735 EXC_XFER_LITE(0x1000, timer_interrupt)
737 /* Fixed Interval Timer (FIT) Exception. (from 0x1010) */
738 FITException:
739 NORMAL_EXCEPTION_PROLOG
740 addi r3,r1,STACK_FRAME_OVERHEAD;
741 EXC_XFER_EE(0x1010, unknown_exception)
743 /* Watchdog Timer (WDT) Exception. (from 0x1020) */
744 WDTException:
745 CRITICAL_EXCEPTION_PROLOG;
746 addi r3,r1,STACK_FRAME_OVERHEAD;
747 EXC_XFER_TEMPLATE(WatchdogException, 0x1020+2,
748 (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)),
749 NOCOPY, crit_transfer_to_handler,
750 ret_from_crit_exc)
752 /*
753 * The other Data TLB exceptions bail out to this point
754 * if they can't resolve the lightweight TLB fault.
755 */
756 DataAccess:
757 NORMAL_EXCEPTION_PROLOG
758 mfspr r5,SPRN_ESR /* Grab the ESR, save it, pass arg3 */
759 stw r5,_ESR(r11)
760 mfspr r4,SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */
761 EXC_XFER_LITE(0x300, handle_page_fault)
763 /* Other PowerPC processors, namely those derived from the 6xx-series
764 * have vectors from 0x2100 through 0x2F00 defined, but marked as reserved.
765 * However, for the 4xx-series processors these are neither defined nor
766 * reserved.
767 */
769 /* Damn, I came up one instruction too many to fit into the
770 * exception space :-). Both the instruction and data TLB
771 * miss get to this point to load the TLB.
772 * r10 - TLB_TAG value
773 * r11 - Linux PTE
774 * r12, r9 - available to use
775 * PID - loaded with proper value when we get here
776 * Upon exit, we reload everything and RFI.
777 * Actually, it will fit now, but oh well.....a common place
778 * to load the TLB.
779 */
780 tlb_4xx_index:
781 .long 0
782 finish_tlb_load:
783 /* load the next available TLB index.
784 */
785 lwz r9, tlb_4xx_index@l(0)
786 addi r9, r9, 1
787 andi. r9, r9, (PPC40X_TLB_SIZE-1)
788 stw r9, tlb_4xx_index@l(0)
790 6:
791 /*
792 * Clear out the software-only bits in the PTE to generate the
793 * TLB_DATA value. These are the bottom 2 bits of the RPM, the
794 * top 3 bits of the zone field, and M.
795 */
796 li r12, 0x0ce2
797 andc r11, r11, r12
799 tlbwe r11, r9, TLB_DATA /* Load TLB LO */
800 tlbwe r10, r9, TLB_TAG /* Load TLB HI */
802 /* Done...restore registers and get out of here.
803 */
804 #ifdef CONFIG_403GCX
805 lwz r12, 12(r0)
806 lwz r11, 8(r0)
807 mtspr SPRN_PID, r12
808 mtcr r11
809 lwz r9, 4(r0)
810 lwz r12, 0(r0)
811 #else
812 mfspr r12, SPRN_SPRG_SCRATCH5
813 mfspr r11, SPRN_SPRG_SCRATCH6
814 mtspr SPRN_PID, r12
815 mtcr r11
816 mfspr r9, SPRN_SPRG_SCRATCH4
817 mfspr r12, SPRN_SPRG_SCRATCH3
818 #endif
819 mfspr r11, SPRN_SPRG_SCRATCH1
820 mfspr r10, SPRN_SPRG_SCRATCH0
821 PPC405_ERR77_SYNC
822 rfi /* Should sync shadow TLBs */
823 b . /* prevent prefetch past rfi */
825 /* This is where the main kernel code starts.
826 */
827 start_here:
829 /* ptr to current */
830 lis r2,init_task@h
831 ori r2,r2,init_task@l
833 /* ptr to phys current thread */
834 tophys(r4,r2)
835 addi r4,r4,THREAD /* init task's THREAD */
836 mtspr SPRN_SPRG_THREAD,r4
838 /* stack */
839 lis r1,init_thread_union@ha
840 addi r1,r1,init_thread_union@l
841 li r0,0
842 stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
844 bl early_init /* We have to do this with MMU on */
846 /*
847 * Decide what sort of machine this is and initialize the MMU.
848 */
849 li r3,0
850 mr r4,r31
851 bl machine_init
852 bl MMU_init
854 /* Go back to running unmapped so we can load up new values
855 * and change to using our exception vectors.
856 * On the 4xx, all we have to do is invalidate the TLB to clear
857 * the old 16M byte TLB mappings.
858 */
859 lis r4,2f@h
860 ori r4,r4,2f@l
861 tophys(r4,r4)
862 lis r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@h
863 ori r3,r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@l
864 mtspr SPRN_SRR0,r4
865 mtspr SPRN_SRR1,r3
866 rfi
867 b . /* prevent prefetch past rfi */
869 /* Load up the kernel context */
870 2:
871 sync /* Flush to memory before changing TLB */
872 tlbia
873 isync /* Flush shadow TLBs */
875 /* set up the PTE pointers for the Abatron bdiGDB.
876 */
877 lis r6, swapper_pg_dir@h
878 ori r6, r6, swapper_pg_dir@l
879 lis r5, abatron_pteptrs@h
880 ori r5, r5, abatron_pteptrs@l
881 stw r5, 0xf0(r0) /* Must match your Abatron config file */
882 tophys(r5,r5)
883 stw r6, 0(r5)
885 /* Now turn on the MMU for real! */
886 lis r4,MSR_KERNEL@h
887 ori r4,r4,MSR_KERNEL@l
888 lis r3,start_kernel@h
889 ori r3,r3,start_kernel@l
890 mtspr SPRN_SRR0,r3
891 mtspr SPRN_SRR1,r4
892 rfi /* enable MMU and jump to start_kernel */
893 b . /* prevent prefetch past rfi */
895 /* Set up the initial MMU state so we can do the first level of
896 * kernel initialization. This maps the first 16 MBytes of memory 1:1
897 * virtual to physical and more importantly sets the cache mode.
898 */
899 initial_mmu:
900 tlbia /* Invalidate all TLB entries */
901 isync
903 /* We should still be executing code at physical address 0x0000xxxx
904 * at this point. However, start_here is at virtual address
905 * 0xC000xxxx. So, set up a TLB mapping to cover this once
906 * translation is enabled.
907 */
909 lis r3,KERNELBASE@h /* Load the kernel virtual address */
910 ori r3,r3,KERNELBASE@l
911 tophys(r4,r3) /* Load the kernel physical address */
913 iccci r0,r3 /* Invalidate the i-cache before use */
915 /* Load the kernel PID.
916 */
917 li r0,0
918 mtspr SPRN_PID,r0
919 sync
921 /* Configure and load one entry into TLB slots 63 */
922 clrrwi r4,r4,10 /* Mask off the real page number */
923 ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */
925 clrrwi r3,r3,10 /* Mask off the effective page number */
926 ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M))
928 li r0,63 /* TLB slot 63 */
930 tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */
931 tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */
933 isync
935 /* Establish the exception vector base
936 */
937 lis r4,KERNELBASE@h /* EVPR only uses the high 16-bits */
938 tophys(r0,r4) /* Use the physical address */
939 mtspr SPRN_EVPR,r0
941 blr
943 _GLOBAL(abort)
944 mfspr r13,SPRN_DBCR0
945 oris r13,r13,DBCR0_RST_SYSTEM@h
946 mtspr SPRN_DBCR0,r13
948 _GLOBAL(set_context)
950 #ifdef CONFIG_BDI_SWITCH
951 /* Context switch the PTE pointer for the Abatron BDI2000.
952 * The PGDIR is the second parameter.
953 */
954 lis r5, KERNELBASE@h
955 lwz r5, 0xf0(r5)
956 stw r4, 0x4(r5)
957 #endif
958 sync
959 mtspr SPRN_PID,r3
960 isync /* Need an isync to flush shadow */
961 /* TLBs after changing PID */
962 blr
964 /* We put a few things here that have to be page-aligned. This stuff
965 * goes at the beginning of the data segment, which is page-aligned.
966 */
967 .data
968 .align 12
969 .globl sdata
970 sdata:
971 .globl empty_zero_page
972 empty_zero_page:
973 .space 4096
974 .globl swapper_pg_dir
975 swapper_pg_dir:
976 .space PGD_TABLE_SIZE
978 /* Room for two PTE pointers, usually the kernel and current user pointers
979 * to their respective root page table.
980 */
981 abatron_pteptrs:
982 .space 8