| blob | b68cb173ba2c6a500c37f369b9daadcf8c519d0c |
1 /*
2 * PowerPC version
3 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
4 * Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
5 * Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
6 * Low-level exception handlers and MMU support
7 * rewritten by Paul Mackerras.
8 * Copyright (C) 1996 Paul Mackerras.
9 * MPC8xx modifications by Dan Malek
10 * Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
11 *
12 * This file contains low-level support and setup for PowerPC 8xx
13 * embedded processors, including trap and interrupt dispatch.
14 *
15 * This program is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU General Public License
17 * as published by the Free Software Foundation; either version
18 * 2 of the License, or (at your option) any later version.
19 *
20 */
22 #include <linux/init.h>
23 #include <asm/processor.h>
24 #include <asm/page.h>
25 #include <asm/mmu.h>
26 #include <asm/cache.h>
27 #include <asm/pgtable.h>
28 #include <asm/cputable.h>
29 #include <asm/thread_info.h>
30 #include <asm/ppc_asm.h>
31 #include <asm/asm-offsets.h>
32 #include <asm/ptrace.h>
34 /* Macro to make the code more readable. */
35 #ifdef CONFIG_8xx_CPU6
36 #define DO_8xx_CPU6(val, reg) \
37 li reg, val; \
38 stw reg, 12(r0); \
39 lwz reg, 12(r0);
40 #else
41 #define DO_8xx_CPU6(val, reg)
42 #endif
43 __HEAD
44 _ENTRY(_stext);
45 _ENTRY(_start);
47 /* MPC8xx
48 * This port was done on an MBX board with an 860. Right now I only
49 * support an ELF compressed (zImage) boot from EPPC-Bug because the
50 * code there loads up some registers before calling us:
51 * r3: ptr to board info data
52 * r4: initrd_start or if no initrd then 0
53 * r5: initrd_end - unused if r4 is 0
54 * r6: Start of command line string
55 * r7: End of command line string
56 *
57 * I decided to use conditional compilation instead of checking PVR and
58 * adding more processor specific branches around code I don't need.
59 * Since this is an embedded processor, I also appreciate any memory
60 * savings I can get.
61 *
62 * The MPC8xx does not have any BATs, but it supports large page sizes.
63 * We first initialize the MMU to support 8M byte pages, then load one
64 * entry into each of the instruction and data TLBs to map the first
65 * 8M 1:1. I also mapped an additional I/O space 1:1 so we can get to
66 * the "internal" processor registers before MMU_init is called.
67 *
68 * The TLB code currently contains a major hack. Since I use the condition
69 * code register, I have to save and restore it. I am out of registers, so
70 * I just store it in memory location 0 (the TLB handlers are not reentrant).
71 * To avoid making any decisions, I need to use the "segment" valid bit
72 * in the first level table, but that would require many changes to the
73 * Linux page directory/table functions that I don't want to do right now.
74 *
75 * -- Dan
76 */
77 .globl __start
78 __start:
79 mr r31,r3 /* save device tree ptr */
81 /* We have to turn on the MMU right away so we get cache modes
82 * set correctly.
83 */
84 bl initial_mmu
86 /* We now have the lower 8 Meg mapped into TLB entries, and the caches
87 * ready to work.
88 */
90 turn_on_mmu:
91 mfmsr r0
92 ori r0,r0,MSR_DR|MSR_IR
93 mtspr SPRN_SRR1,r0
94 lis r0,start_here@h
95 ori r0,r0,start_here@l
96 mtspr SPRN_SRR0,r0
97 SYNC
98 rfi /* enables MMU */
100 /*
101 * Exception entry code. This code runs with address translation
102 * turned off, i.e. using physical addresses.
103 * We assume sprg3 has the physical address of the current
104 * task's thread_struct.
105 */
106 #define EXCEPTION_PROLOG \
107 mtspr SPRN_SPRG_SCRATCH0,r10; \
108 mtspr SPRN_SPRG_SCRATCH1,r11; \
109 mfcr r10; \
110 EXCEPTION_PROLOG_1; \
111 EXCEPTION_PROLOG_2
113 #define EXCEPTION_PROLOG_1 \
114 mfspr r11,SPRN_SRR1; /* check whether user or kernel */ \
115 andi. r11,r11,MSR_PR; \
116 tophys(r11,r1); /* use tophys(r1) if kernel */ \
117 beq 1f; \
118 mfspr r11,SPRN_SPRG_THREAD; \
119 lwz r11,THREAD_INFO-THREAD(r11); \
120 addi r11,r11,THREAD_SIZE; \
121 tophys(r11,r11); \
122 1: subi r11,r11,INT_FRAME_SIZE /* alloc exc. frame */
125 #define EXCEPTION_PROLOG_2 \
126 CLR_TOP32(r11); \
127 stw r10,_CCR(r11); /* save registers */ \
128 stw r12,GPR12(r11); \
129 stw r9,GPR9(r11); \
130 mfspr r10,SPRN_SPRG_SCRATCH0; \
131 stw r10,GPR10(r11); \
132 mfspr r12,SPRN_SPRG_SCRATCH1; \
133 stw r12,GPR11(r11); \
134 mflr r10; \
135 stw r10,_LINK(r11); \
136 mfspr r12,SPRN_SRR0; \
137 mfspr r9,SPRN_SRR1; \
138 stw r1,GPR1(r11); \
139 stw r1,0(r11); \
140 tovirt(r1,r11); /* set new kernel sp */ \
141 li r10,MSR_KERNEL & ~(MSR_IR|MSR_DR); /* can take exceptions */ \
142 MTMSRD(r10); /* (except for mach check in rtas) */ \
143 stw r0,GPR0(r11); \
144 SAVE_4GPRS(3, r11); \
145 SAVE_2GPRS(7, r11)
147 /*
148 * Note: code which follows this uses cr0.eq (set if from kernel),
149 * r11, r12 (SRR0), and r9 (SRR1).
150 *
151 * Note2: once we have set r1 we are in a position to take exceptions
152 * again, and we could thus set MSR:RI at that point.
153 */
155 /*
156 * Exception vectors.
157 */
158 #define EXCEPTION(n, label, hdlr, xfer) \
159 . = n; \
160 label: \
161 EXCEPTION_PROLOG; \
162 addi r3,r1,STACK_FRAME_OVERHEAD; \
163 xfer(n, hdlr)
165 #define EXC_XFER_TEMPLATE(n, hdlr, trap, copyee, tfer, ret) \
166 li r10,trap; \
167 stw r10,_TRAP(r11); \
168 li r10,MSR_KERNEL; \
169 copyee(r10, r9); \
170 bl tfer; \
171 i##n: \
172 .long hdlr; \
173 .long ret
175 #define COPY_EE(d, s) rlwimi d,s,0,16,16
176 #define NOCOPY(d, s)
178 #define EXC_XFER_STD(n, hdlr) \
179 EXC_XFER_TEMPLATE(n, hdlr, n, NOCOPY, transfer_to_handler_full, \
180 ret_from_except_full)
182 #define EXC_XFER_LITE(n, hdlr) \
183 EXC_XFER_TEMPLATE(n, hdlr, n+1, NOCOPY, transfer_to_handler, \
184 ret_from_except)
186 #define EXC_XFER_EE(n, hdlr) \
187 EXC_XFER_TEMPLATE(n, hdlr, n, COPY_EE, transfer_to_handler_full, \
188 ret_from_except_full)
190 #define EXC_XFER_EE_LITE(n, hdlr) \
191 EXC_XFER_TEMPLATE(n, hdlr, n+1, COPY_EE, transfer_to_handler, \
192 ret_from_except)
194 /* System reset */
195 EXCEPTION(0x100, Reset, unknown_exception, EXC_XFER_STD)
197 /* Machine check */
198 . = 0x200
199 MachineCheck:
200 EXCEPTION_PROLOG
201 mfspr r4,SPRN_DAR
202 stw r4,_DAR(r11)
203 li r5,0x00f0
204 mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */
205 mfspr r5,SPRN_DSISR
206 stw r5,_DSISR(r11)
207 addi r3,r1,STACK_FRAME_OVERHEAD
208 EXC_XFER_STD(0x200, machine_check_exception)
210 /* Data access exception.
211 * This is "never generated" by the MPC8xx. We jump to it for other
212 * translation errors.
213 */
214 . = 0x300
215 DataAccess:
216 EXCEPTION_PROLOG
217 mfspr r10,SPRN_DSISR
218 stw r10,_DSISR(r11)
219 mr r5,r10
220 mfspr r4,SPRN_DAR
221 li r10,0x00f0
222 mtspr SPRN_DAR,r10 /* Tag DAR, to be used in DTLB Error */
223 EXC_XFER_EE_LITE(0x300, handle_page_fault)
225 /* Instruction access exception.
226 * This is "never generated" by the MPC8xx. We jump to it for other
227 * translation errors.
228 */
229 . = 0x400
230 InstructionAccess:
231 EXCEPTION_PROLOG
232 mr r4,r12
233 mr r5,r9
234 EXC_XFER_EE_LITE(0x400, handle_page_fault)
236 /* External interrupt */
237 EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
239 /* Alignment exception */
240 . = 0x600
241 Alignment:
242 EXCEPTION_PROLOG
243 mfspr r4,SPRN_DAR
244 stw r4,_DAR(r11)
245 li r5,0x00f0
246 mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */
247 mfspr r5,SPRN_DSISR
248 stw r5,_DSISR(r11)
249 addi r3,r1,STACK_FRAME_OVERHEAD
250 EXC_XFER_EE(0x600, alignment_exception)
252 /* Program check exception */
253 EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)
255 /* No FPU on MPC8xx. This exception is not supposed to happen.
256 */
257 EXCEPTION(0x800, FPUnavailable, unknown_exception, EXC_XFER_STD)
259 /* Decrementer */
260 EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE)
262 EXCEPTION(0xa00, Trap_0a, unknown_exception, EXC_XFER_EE)
263 EXCEPTION(0xb00, Trap_0b, unknown_exception, EXC_XFER_EE)
265 /* System call */
266 . = 0xc00
267 SystemCall:
268 EXCEPTION_PROLOG
269 EXC_XFER_EE_LITE(0xc00, DoSyscall)
271 /* Single step - not used on 601 */
272 EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)
273 EXCEPTION(0xe00, Trap_0e, unknown_exception, EXC_XFER_EE)
274 EXCEPTION(0xf00, Trap_0f, unknown_exception, EXC_XFER_EE)
276 /* On the MPC8xx, this is a software emulation interrupt. It occurs
277 * for all unimplemented and illegal instructions.
278 */
279 EXCEPTION(0x1000, SoftEmu, SoftwareEmulation, EXC_XFER_STD)
281 . = 0x1100
282 /*
283 * For the MPC8xx, this is a software tablewalk to load the instruction
284 * TLB. It is modelled after the example in the Motorola manual. The task
285 * switch loads the M_TWB register with the pointer to the first level table.
286 * If we discover there is no second level table (value is zero) or if there
287 * is an invalid pte, we load that into the TLB, which causes another fault
288 * into the TLB Error interrupt where we can handle such problems.
289 * We have to use the MD_xxx registers for the tablewalk because the
290 * equivalent MI_xxx registers only perform the attribute functions.
291 */
292 InstructionTLBMiss:
293 #ifdef CONFIG_8xx_CPU6
294 stw r3, 8(r0)
295 #endif
296 DO_8xx_CPU6(0x3f80, r3)
297 mtspr SPRN_M_TW, r10 /* Save a couple of working registers */
298 mfcr r10
299 #ifdef CONFIG_8xx_CPU6
300 stw r10, 0(r0)
301 stw r11, 4(r0)
302 #else
303 mtspr SPRN_DAR, r10
304 mtspr SPRN_SPRG2, r11
305 #endif
306 mfspr r10, SPRN_SRR0 /* Get effective address of fault */
307 #ifdef CONFIG_8xx_CPU15
308 addi r11, r10, 0x1000
309 tlbie r11
310 addi r11, r10, -0x1000
311 tlbie r11
312 #endif
313 DO_8xx_CPU6(0x3780, r3)
314 mtspr SPRN_MD_EPN, r10 /* Have to use MD_EPN for walk, MI_EPN can't */
315 mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */
317 /* If we are faulting a kernel address, we have to use the
318 * kernel page tables.
319 */
320 #ifdef CONFIG_MODULES
321 /* Only modules will cause ITLB Misses as we always
322 * pin the first 8MB of kernel memory */
323 andi. r11, r10, 0x0800 /* Address >= 0x80000000 */
324 beq 3f
325 lis r11, swapper_pg_dir@h
326 ori r11, r11, swapper_pg_dir@l
327 rlwimi r10, r11, 0, 2, 19
328 3:
329 #endif
330 lwz r11, 0(r10) /* Get the level 1 entry */
331 rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */
332 beq 2f /* If zero, don't try to find a pte */
334 /* We have a pte table, so load the MI_TWC with the attributes
335 * for this "segment."
336 */
337 ori r11,r11,1 /* Set valid bit */
338 DO_8xx_CPU6(0x2b80, r3)
339 mtspr SPRN_MI_TWC, r11 /* Set segment attributes */
340 DO_8xx_CPU6(0x3b80, r3)
341 mtspr SPRN_MD_TWC, r11 /* Load pte table base address */
342 mfspr r11, SPRN_MD_TWC /* ....and get the pte address */
343 lwz r10, 0(r11) /* Get the pte */
345 #ifdef CONFIG_SWAP
346 andi. r11, r10, _PAGE_ACCESSED | _PAGE_PRESENT
347 cmpwi cr0, r11, _PAGE_ACCESSED | _PAGE_PRESENT
348 bne- cr0, 2f
349 #endif
350 /* The Linux PTE won't go exactly into the MMU TLB.
351 * Software indicator bits 21 and 28 must be clear.
352 * Software indicator bits 24, 25, 26, and 27 must be
353 * set. All other Linux PTE bits control the behavior
354 * of the MMU.
355 */
356 li r11, 0x00f0
357 rlwimi r10, r11, 0, 0x07f8 /* Set 24-27, clear 21-23,28 */
358 DO_8xx_CPU6(0x2d80, r3)
359 mtspr SPRN_MI_RPN, r10 /* Update TLB entry */
361 /* Restore registers */
362 #ifndef CONFIG_8xx_CPU6
363 mfspr r10, SPRN_DAR
364 mtcr r10
365 mtspr SPRN_DAR, r11 /* Tag DAR */
366 mfspr r11, SPRN_SPRG2
367 #else
368 lwz r11, 0(r0)
369 mtcr r11
370 lwz r11, 4(r0)
371 lwz r3, 8(r0)
372 #endif
373 mfspr r10, SPRN_M_TW
374 rfi
375 2:
376 mfspr r11, SPRN_SRR1
377 /* clear all error bits as TLB Miss
378 * sets a few unconditionally
379 */
380 rlwinm r11, r11, 0, 0xffff
381 mtspr SPRN_SRR1, r11
383 /* Restore registers */
384 #ifndef CONFIG_8xx_CPU6
385 mfspr r10, SPRN_DAR
386 mtcr r10
387 li r11, 0x00f0
388 mtspr SPRN_DAR, r11 /* Tag DAR */
389 mfspr r11, SPRN_SPRG2
390 #else
391 lwz r11, 0(r0)
392 mtcr r11
393 lwz r11, 4(r0)
394 lwz r3, 8(r0)
395 #endif
396 mfspr r10, SPRN_M_TW
397 b InstructionAccess
399 . = 0x1200
400 DataStoreTLBMiss:
401 #ifdef CONFIG_8xx_CPU6
402 stw r3, 8(r0)
403 #endif
404 DO_8xx_CPU6(0x3f80, r3)
405 mtspr SPRN_M_TW, r10 /* Save a couple of working registers */
406 mfcr r10
407 #ifdef CONFIG_8xx_CPU6
408 stw r10, 0(r0)
409 stw r11, 4(r0)
410 #else
411 mtspr SPRN_DAR, r10
412 mtspr SPRN_SPRG2, r11
413 #endif
414 mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */
416 /* If we are faulting a kernel address, we have to use the
417 * kernel page tables.
418 */
419 andi. r11, r10, 0x0800
420 beq 3f
421 lis r11, swapper_pg_dir@h
422 ori r11, r11, swapper_pg_dir@l
423 rlwimi r10, r11, 0, 2, 19
424 3:
425 lwz r11, 0(r10) /* Get the level 1 entry */
426 rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */
427 beq 2f /* If zero, don't try to find a pte */
429 /* We have a pte table, so load fetch the pte from the table.
430 */
431 ori r11, r11, 1 /* Set valid bit in physical L2 page */
432 DO_8xx_CPU6(0x3b80, r3)
433 mtspr SPRN_MD_TWC, r11 /* Load pte table base address */
434 mfspr r10, SPRN_MD_TWC /* ....and get the pte address */
435 lwz r10, 0(r10) /* Get the pte */
437 /* Insert the Guarded flag into the TWC from the Linux PTE.
438 * It is bit 27 of both the Linux PTE and the TWC (at least
439 * I got that right :-). It will be better when we can put
440 * this into the Linux pgd/pmd and load it in the operation
441 * above.
442 */
443 rlwimi r11, r10, 0, 27, 27
444 /* Insert the WriteThru flag into the TWC from the Linux PTE.
445 * It is bit 25 in the Linux PTE and bit 30 in the TWC
446 */
447 rlwimi r11, r10, 32-5, 30, 30
448 DO_8xx_CPU6(0x3b80, r3)
449 mtspr SPRN_MD_TWC, r11
451 /* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
452 * We also need to know if the insn is a load/store, so:
453 * Clear _PAGE_PRESENT and load that which will
454 * trap into DTLB Error with store bit set accordinly.
455 */
456 /* PRESENT=0x1, ACCESSED=0x20
457 * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5));
458 * r10 = (r10 & ~PRESENT) | r11;
459 */
460 #ifdef CONFIG_SWAP
461 rlwinm r11, r10, 32-5, _PAGE_PRESENT
462 and r11, r11, r10
463 rlwimi r10, r11, 0, _PAGE_PRESENT
464 #endif
465 /* Honour kernel RO, User NA */
466 /* 0x200 == Extended encoding, bit 22 */
467 rlwimi r10, r10, 32-2, 0x200 /* Copy USER to bit 22, 0x200 */
468 /* r11 = (r10 & _PAGE_RW) >> 1 */
469 rlwinm r11, r10, 32-1, 0x200
470 or r10, r11, r10
471 /* invert RW and 0x200 bits */
472 xori r10, r10, _PAGE_RW | 0x200
474 /* The Linux PTE won't go exactly into the MMU TLB.
475 * Software indicator bits 22 and 28 must be clear.
476 * Software indicator bits 24, 25, 26, and 27 must be
477 * set. All other Linux PTE bits control the behavior
478 * of the MMU.
479 */
480 2: li r11, 0x00f0
481 rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */
482 DO_8xx_CPU6(0x3d80, r3)
483 mtspr SPRN_MD_RPN, r10 /* Update TLB entry */
485 /* Restore registers */
486 #ifndef CONFIG_8xx_CPU6
487 mfspr r10, SPRN_DAR
488 mtcr r10
489 mtspr SPRN_DAR, r11 /* Tag DAR */
490 mfspr r11, SPRN_SPRG2
491 #else
492 mtspr SPRN_DAR, r11 /* Tag DAR */
493 lwz r11, 0(r0)
494 mtcr r11
495 lwz r11, 4(r0)
496 lwz r3, 8(r0)
497 #endif
498 mfspr r10, SPRN_M_TW
499 rfi
501 /* This is an instruction TLB error on the MPC8xx. This could be due
502 * to many reasons, such as executing guarded memory or illegal instruction
503 * addresses. There is nothing to do but handle a big time error fault.
504 */
505 . = 0x1300
506 InstructionTLBError:
507 b InstructionAccess
509 /* This is the data TLB error on the MPC8xx. This could be due to
510 * many reasons, including a dirty update to a pte. We can catch that
511 * one here, but anything else is an error. First, we track down the
512 * Linux pte. If it is valid, write access is allowed, but the
513 * page dirty bit is not set, we will set it and reload the TLB. For
514 * any other case, we bail out to a higher level function that can
515 * handle it.
516 */
517 . = 0x1400
518 DataTLBError:
519 #ifdef CONFIG_8xx_CPU6
520 stw r3, 8(r0)
521 #endif
522 DO_8xx_CPU6(0x3f80, r3)
523 mtspr SPRN_M_TW, r10 /* Save a couple of working registers */
524 mfcr r10
525 stw r10, 0(r0)
526 stw r11, 4(r0)
528 mfspr r10, SPRN_DAR
529 cmpwi cr0, r10, 0x00f0
530 beq- FixupDAR /* must be a buggy dcbX, icbi insn. */
531 DARFixed:/* Return from dcbx instruction bug workaround, r10 holds value of DAR */
532 mfspr r10, SPRN_M_TW /* Restore registers */
533 lwz r11, 0(r0)
534 mtcr r11
535 lwz r11, 4(r0)
536 #ifdef CONFIG_8xx_CPU6
537 lwz r3, 8(r0)
538 #endif
539 b DataAccess
541 EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
542 EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
543 EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE)
544 EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_EE)
545 EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_EE)
546 EXCEPTION(0x1a00, Trap_1a, unknown_exception, EXC_XFER_EE)
547 EXCEPTION(0x1b00, Trap_1b, unknown_exception, EXC_XFER_EE)
549 /* On the MPC8xx, these next four traps are used for development
550 * support of breakpoints and such. Someday I will get around to
551 * using them.
552 */
553 EXCEPTION(0x1c00, Trap_1c, unknown_exception, EXC_XFER_EE)
554 EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_EE)
555 EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_EE)
556 EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_EE)
558 . = 0x2000
560 /* This is the procedure to calculate the data EA for buggy dcbx,dcbi instructions
561 * by decoding the registers used by the dcbx instruction and adding them.
562 * DAR is set to the calculated address and r10 also holds the EA on exit.
563 */
564 /* define if you don't want to use self modifying code */
565 #define NO_SELF_MODIFYING_CODE
566 FixupDAR:/* Entry point for dcbx workaround. */
567 /* fetch instruction from memory. */
568 mfspr r10, SPRN_SRR0
569 andis. r11, r10, 0x8000 /* Address >= 0x80000000 */
570 DO_8xx_CPU6(0x3780, r3)
571 mtspr SPRN_MD_EPN, r10
572 mfspr r11, SPRN_M_TWB /* Get level 1 table entry address */
573 beq- 3f /* Branch if user space */
574 lis r11, (swapper_pg_dir-PAGE_OFFSET)@h
575 ori r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l
576 rlwimi r11, r10, 32-20, 0xffc /* r11 = r11&~0xffc|(r10>>20)&0xffc */
577 3: lwz r11, 0(r11) /* Get the level 1 entry */
578 DO_8xx_CPU6(0x3b80, r3)
579 mtspr SPRN_MD_TWC, r11 /* Load pte table base address */
580 mfspr r11, SPRN_MD_TWC /* ....and get the pte address */
581 lwz r11, 0(r11) /* Get the pte */
582 /* concat physical page address(r11) and page offset(r10) */
583 rlwimi r11, r10, 0, 20, 31
584 lwz r11,0(r11)
585 /* Check if it really is a dcbx instruction. */
586 /* dcbt and dcbtst does not generate DTLB Misses/Errors,
587 * no need to include them here */
588 srwi r10, r11, 26 /* check if major OP code is 31 */
589 cmpwi cr0, r10, 31
590 bne- 141f
591 rlwinm r10, r11, 0, 21, 30
592 cmpwi cr0, r10, 2028 /* Is dcbz? */
593 beq+ 142f
594 cmpwi cr0, r10, 940 /* Is dcbi? */
595 beq+ 142f
596 cmpwi cr0, r10, 108 /* Is dcbst? */
597 beq+ 144f /* Fix up store bit! */
598 cmpwi cr0, r10, 172 /* Is dcbf? */
599 beq+ 142f
600 cmpwi cr0, r10, 1964 /* Is icbi? */
601 beq+ 142f
602 141: mfspr r10, SPRN_DAR /* r10 must hold DAR at exit */
603 b DARFixed /* Nope, go back to normal TLB processing */
605 144: mfspr r10, SPRN_DSISR
606 rlwinm r10, r10,0,7,5 /* Clear store bit for buggy dcbst insn */
607 mtspr SPRN_DSISR, r10
608 142: /* continue, it was a dcbx, dcbi instruction. */
609 #ifdef CONFIG_8xx_CPU6
610 lwz r3, 8(r0) /* restore r3 from memory */
611 #endif
612 #ifndef NO_SELF_MODIFYING_CODE
613 andis. r10,r11,0x1f /* test if reg RA is r0 */
614 li r10,modified_instr@l
615 dcbtst r0,r10 /* touch for store */
616 rlwinm r11,r11,0,0,20 /* Zero lower 10 bits */
617 oris r11,r11,640 /* Transform instr. to a "add r10,RA,RB" */
618 ori r11,r11,532
619 stw r11,0(r10) /* store add/and instruction */
620 dcbf 0,r10 /* flush new instr. to memory. */
621 icbi 0,r10 /* invalidate instr. cache line */
622 lwz r11, 4(r0) /* restore r11 from memory */
623 mfspr r10, SPRN_M_TW /* restore r10 from M_TW */
624 isync /* Wait until new instr is loaded from memory */
625 modified_instr:
626 .space 4 /* this is where the add instr. is stored */
627 bne+ 143f
628 subf r10,r0,r10 /* r10=r10-r0, only if reg RA is r0 */
629 143: mtdar r10 /* store faulting EA in DAR */
630 b DARFixed /* Go back to normal TLB handling */
631 #else
632 mfctr r10
633 mtdar r10 /* save ctr reg in DAR */
634 rlwinm r10, r11, 24, 24, 28 /* offset into jump table for reg RB */
635 addi r10, r10, 150f@l /* add start of table */
636 mtctr r10 /* load ctr with jump address */
637 xor r10, r10, r10 /* sum starts at zero */
638 bctr /* jump into table */
639 150:
640 add r10, r10, r0 ;b 151f
641 add r10, r10, r1 ;b 151f
642 add r10, r10, r2 ;b 151f
643 add r10, r10, r3 ;b 151f
644 add r10, r10, r4 ;b 151f
645 add r10, r10, r5 ;b 151f
646 add r10, r10, r6 ;b 151f
647 add r10, r10, r7 ;b 151f
648 add r10, r10, r8 ;b 151f
649 add r10, r10, r9 ;b 151f
650 mtctr r11 ;b 154f /* r10 needs special handling */
651 mtctr r11 ;b 153f /* r11 needs special handling */
652 add r10, r10, r12 ;b 151f
653 add r10, r10, r13 ;b 151f
654 add r10, r10, r14 ;b 151f
655 add r10, r10, r15 ;b 151f
656 add r10, r10, r16 ;b 151f
657 add r10, r10, r17 ;b 151f
658 add r10, r10, r18 ;b 151f
659 add r10, r10, r19 ;b 151f
660 add r10, r10, r20 ;b 151f
661 add r10, r10, r21 ;b 151f
662 add r10, r10, r22 ;b 151f
663 add r10, r10, r23 ;b 151f
664 add r10, r10, r24 ;b 151f
665 add r10, r10, r25 ;b 151f
666 add r10, r10, r26 ;b 151f
667 add r10, r10, r27 ;b 151f
668 add r10, r10, r28 ;b 151f
669 add r10, r10, r29 ;b 151f
670 add r10, r10, r30 ;b 151f
671 add r10, r10, r31
672 151:
673 rlwinm. r11,r11,19,24,28 /* offset into jump table for reg RA */
674 beq 152f /* if reg RA is zero, don't add it */
675 addi r11, r11, 150b@l /* add start of table */
676 mtctr r11 /* load ctr with jump address */
677 rlwinm r11,r11,0,16,10 /* make sure we don't execute this more than once */
678 bctr /* jump into table */
679 152:
680 mfdar r11
681 mtctr r11 /* restore ctr reg from DAR */
682 mtdar r10 /* save fault EA to DAR */
683 b DARFixed /* Go back to normal TLB handling */
685 /* special handling for r10,r11 since these are modified already */
686 153: lwz r11, 4(r0) /* load r11 from memory */
687 b 155f
688 154: mfspr r11, SPRN_M_TW /* load r10 from M_TW */
689 155: add r10, r10, r11 /* add it */
690 mfctr r11 /* restore r11 */
691 b 151b
692 #endif
694 .globl giveup_fpu
695 giveup_fpu:
696 blr
698 /*
699 * This is where the main kernel code starts.
700 */
701 start_here:
702 /* ptr to current */
703 lis r2,init_task@h
704 ori r2,r2,init_task@l
706 /* ptr to phys current thread */
707 tophys(r4,r2)
708 addi r4,r4,THREAD /* init task's THREAD */
709 mtspr SPRN_SPRG_THREAD,r4
711 /* stack */
712 lis r1,init_thread_union@ha
713 addi r1,r1,init_thread_union@l
714 li r0,0
715 stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
717 bl early_init /* We have to do this with MMU on */
719 /*
720 * Decide what sort of machine this is and initialize the MMU.
721 */
722 li r3,0
723 mr r4,r31
724 bl machine_init
725 bl MMU_init
727 /*
728 * Go back to running unmapped so we can load up new values
729 * and change to using our exception vectors.
730 * On the 8xx, all we have to do is invalidate the TLB to clear
731 * the old 8M byte TLB mappings and load the page table base register.
732 */
733 /* The right way to do this would be to track it down through
734 * init's THREAD like the context switch code does, but this is
735 * easier......until someone changes init's static structures.
736 */
737 lis r6, swapper_pg_dir@h
738 ori r6, r6, swapper_pg_dir@l
739 tophys(r6,r6)
740 #ifdef CONFIG_8xx_CPU6
741 lis r4, cpu6_errata_word@h
742 ori r4, r4, cpu6_errata_word@l
743 li r3, 0x3980
744 stw r3, 12(r4)
745 lwz r3, 12(r4)
746 #endif
747 mtspr SPRN_M_TWB, r6
748 lis r4,2f@h
749 ori r4,r4,2f@l
750 tophys(r4,r4)
751 li r3,MSR_KERNEL & ~(MSR_IR|MSR_DR)
752 mtspr SPRN_SRR0,r4
753 mtspr SPRN_SRR1,r3
754 rfi
755 /* Load up the kernel context */
756 2:
757 SYNC /* Force all PTE updates to finish */
758 tlbia /* Clear all TLB entries */
759 sync /* wait for tlbia/tlbie to finish */
760 TLBSYNC /* ... on all CPUs */
762 /* set up the PTE pointers for the Abatron bdiGDB.
763 */
764 tovirt(r6,r6)
765 lis r5, abatron_pteptrs@h
766 ori r5, r5, abatron_pteptrs@l
767 stw r5, 0xf0(r0) /* Must match your Abatron config file */
768 tophys(r5,r5)
769 stw r6, 0(r5)
771 /* Now turn on the MMU for real! */
772 li r4,MSR_KERNEL
773 lis r3,start_kernel@h
774 ori r3,r3,start_kernel@l
775 mtspr SPRN_SRR0,r3
776 mtspr SPRN_SRR1,r4
777 rfi /* enable MMU and jump to start_kernel */
779 /* Set up the initial MMU state so we can do the first level of
780 * kernel initialization. This maps the first 8 MBytes of memory 1:1
781 * virtual to physical. Also, set the cache mode since that is defined
782 * by TLB entries and perform any additional mapping (like of the IMMR).
783 * If configured to pin some TLBs, we pin the first 8 Mbytes of kernel,
784 * 24 Mbytes of data, and the 8M IMMR space. Anything not covered by
785 * these mappings is mapped by page tables.
786 */
787 initial_mmu:
788 tlbia /* Invalidate all TLB entries */
789 /* Always pin the first 8 MB ITLB to prevent ITLB
790 misses while mucking around with SRR0/SRR1 in asm
791 */
792 lis r8, MI_RSV4I@h
793 ori r8, r8, 0x1c00
795 mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
797 #ifdef CONFIG_PIN_TLB
798 lis r10, (MD_RSV4I | MD_RESETVAL)@h
799 ori r10, r10, 0x1c00
800 mr r8, r10
801 #else
802 lis r10, MD_RESETVAL@h
803 #endif
804 #ifndef CONFIG_8xx_COPYBACK
805 oris r10, r10, MD_WTDEF@h
806 #endif
807 mtspr SPRN_MD_CTR, r10 /* Set data TLB control */
809 /* Now map the lower 8 Meg into the TLBs. For this quick hack,
810 * we can load the instruction and data TLB registers with the
811 * same values.
812 */
813 lis r8, KERNELBASE@h /* Create vaddr for TLB */
814 ori r8, r8, MI_EVALID /* Mark it valid */
815 mtspr SPRN_MI_EPN, r8
816 mtspr SPRN_MD_EPN, r8
817 li r8, MI_PS8MEG /* Set 8M byte page */
818 ori r8, r8, MI_SVALID /* Make it valid */
819 mtspr SPRN_MI_TWC, r8
820 mtspr SPRN_MD_TWC, r8
821 li r8, MI_BOOTINIT /* Create RPN for address 0 */
822 mtspr SPRN_MI_RPN, r8 /* Store TLB entry */
823 mtspr SPRN_MD_RPN, r8
824 lis r8, MI_Kp@h /* Set the protection mode */
825 mtspr SPRN_MI_AP, r8
826 mtspr SPRN_MD_AP, r8
828 /* Map another 8 MByte at the IMMR to get the processor
829 * internal registers (among other things).
830 */
831 #ifdef CONFIG_PIN_TLB
832 addi r10, r10, 0x0100
833 mtspr SPRN_MD_CTR, r10
834 #endif
835 mfspr r9, 638 /* Get current IMMR */
836 andis. r9, r9, 0xff80 /* Get 8Mbyte boundary */
838 mr r8, r9 /* Create vaddr for TLB */
839 ori r8, r8, MD_EVALID /* Mark it valid */
840 mtspr SPRN_MD_EPN, r8
841 li r8, MD_PS8MEG /* Set 8M byte page */
842 ori r8, r8, MD_SVALID /* Make it valid */
843 mtspr SPRN_MD_TWC, r8
844 mr r8, r9 /* Create paddr for TLB */
845 ori r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */
846 mtspr SPRN_MD_RPN, r8
848 #ifdef CONFIG_PIN_TLB
849 /* Map two more 8M kernel data pages.
850 */
851 addi r10, r10, 0x0100
852 mtspr SPRN_MD_CTR, r10
854 lis r8, KERNELBASE@h /* Create vaddr for TLB */
855 addis r8, r8, 0x0080 /* Add 8M */
856 ori r8, r8, MI_EVALID /* Mark it valid */
857 mtspr SPRN_MD_EPN, r8
858 li r9, MI_PS8MEG /* Set 8M byte page */
859 ori r9, r9, MI_SVALID /* Make it valid */
860 mtspr SPRN_MD_TWC, r9
861 li r11, MI_BOOTINIT /* Create RPN for address 0 */
862 addis r11, r11, 0x0080 /* Add 8M */
863 mtspr SPRN_MD_RPN, r11
865 addis r8, r8, 0x0080 /* Add 8M */
866 mtspr SPRN_MD_EPN, r8
867 mtspr SPRN_MD_TWC, r9
868 addis r11, r11, 0x0080 /* Add 8M */
869 mtspr SPRN_MD_RPN, r11
870 #endif
872 /* Since the cache is enabled according to the information we
873 * just loaded into the TLB, invalidate and enable the caches here.
874 * We should probably check/set other modes....later.
875 */
876 lis r8, IDC_INVALL@h
877 mtspr SPRN_IC_CST, r8
878 mtspr SPRN_DC_CST, r8
879 lis r8, IDC_ENABLE@h
880 mtspr SPRN_IC_CST, r8
881 #ifdef CONFIG_8xx_COPYBACK
882 mtspr SPRN_DC_CST, r8
883 #else
884 /* For a debug option, I left this here to easily enable
885 * the write through cache mode
886 */
887 lis r8, DC_SFWT@h
888 mtspr SPRN_DC_CST, r8
889 lis r8, IDC_ENABLE@h
890 mtspr SPRN_DC_CST, r8
891 #endif
892 blr
895 /*
896 * Set up to use a given MMU context.
897 * r3 is context number, r4 is PGD pointer.
898 *
899 * We place the physical address of the new task page directory loaded
900 * into the MMU base register, and set the ASID compare register with
901 * the new "context."
902 */
903 _GLOBAL(set_context)
905 #ifdef CONFIG_BDI_SWITCH
906 /* Context switch the PTE pointer for the Abatron BDI2000.
907 * The PGDIR is passed as second argument.
908 */
909 lis r5, KERNELBASE@h
910 lwz r5, 0xf0(r5)
911 stw r4, 0x4(r5)
912 #endif
914 #ifdef CONFIG_8xx_CPU6
915 lis r6, cpu6_errata_word@h
916 ori r6, r6, cpu6_errata_word@l
917 tophys (r4, r4)
918 li r7, 0x3980
919 stw r7, 12(r6)
920 lwz r7, 12(r6)
921 mtspr SPRN_M_TWB, r4 /* Update MMU base address */
922 li r7, 0x3380
923 stw r7, 12(r6)
924 lwz r7, 12(r6)
925 mtspr SPRN_M_CASID, r3 /* Update context */
926 #else
927 mtspr SPRN_M_CASID,r3 /* Update context */
928 tophys (r4, r4)
929 mtspr SPRN_M_TWB, r4 /* and pgd */
930 #endif
931 SYNC
932 blr
934 #ifdef CONFIG_8xx_CPU6
935 /* It's here because it is unique to the 8xx.
936 * It is important we get called with interrupts disabled. I used to
937 * do that, but it appears that all code that calls this already had
938 * interrupt disabled.
939 */
940 .globl set_dec_cpu6
941 set_dec_cpu6:
942 lis r7, cpu6_errata_word@h
943 ori r7, r7, cpu6_errata_word@l
944 li r4, 0x2c00
945 stw r4, 8(r7)
946 lwz r4, 8(r7)
947 mtspr 22, r3 /* Update Decrementer */
948 SYNC
949 blr
950 #endif
952 /*
953 * We put a few things here that have to be page-aligned.
954 * This stuff goes at the beginning of the data segment,
955 * which is page-aligned.
956 */
957 .data
958 .globl sdata
959 sdata:
960 .globl empty_zero_page
961 empty_zero_page:
962 .space 4096
964 .globl swapper_pg_dir
965 swapper_pg_dir:
966 .space 4096
968 /* Room for two PTE table poiners, usually the kernel and current user
969 * pointer to their respective root page table (pgdir).
970 */
971 abatron_pteptrs:
972 .space 8
974 #ifdef CONFIG_8xx_CPU6
975 .globl cpu6_errata_word
976 cpu6_errata_word:
977 .space 16
978 #endif