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).
12 * This file contains low-level support and setup for PowerPC 8xx
13 * embedded processors, including trap and interrupt dispatch.
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.
22 #include <linux/init.h>
23 #include <asm/processor.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 SPRN_MI_TWC_ADDR 0x2b80
37 #define SPRN_MI_RPN_ADDR 0x2d80
38 #define SPRN_MD_TWC_ADDR 0x3b80
39 #define SPRN_MD_RPN_ADDR 0x3d80
41 #define MTSPR_CPU6(spr, reg, treg) \
42 li treg, spr##_ADDR; \
47 #define MTSPR_CPU6(spr, reg, treg) \
52 * Value for the bits that have fixed value in RPN entries.
53 * Also used for tagging DAR for DTLBerror.
55 #ifdef CONFIG_PPC_16K_PAGES
56 #define RPN_PATTERN (0x00f0 | MD_SPS16K)
58 #define RPN_PATTERN 0x00f0
66 * This port was done on an MBX board with an 860. Right now I only
67 * support an ELF compressed (zImage) boot from EPPC-Bug because the
68 * code there loads up some registers before calling us:
69 * r3: ptr to board info data
70 * r4: initrd_start or if no initrd then 0
71 * r5: initrd_end - unused if r4 is 0
72 * r6: Start of command line string
73 * r7: End of command line string
75 * I decided to use conditional compilation instead of checking PVR and
76 * adding more processor specific branches around code I don't need.
77 * Since this is an embedded processor, I also appreciate any memory
80 * The MPC8xx does not have any BATs, but it supports large page sizes.
81 * We first initialize the MMU to support 8M byte pages, then load one
82 * entry into each of the instruction and data TLBs to map the first
83 * 8M 1:1. I also mapped an additional I/O space 1:1 so we can get to
84 * the "internal" processor registers before MMU_init is called.
86 * The TLB code currently contains a major hack. Since I use the condition
87 * code register, I have to save and restore it. I am out of registers, so
88 * I just store it in memory location 0 (the TLB handlers are not reentrant).
89 * To avoid making any decisions, I need to use the "segment" valid bit
90 * in the first level table, but that would require many changes to the
91 * Linux page directory/table functions that I don't want to do right now.
97 mr r31,r3 /* save device tree ptr */
99 /* We have to turn on the MMU right away so we get cache modes
104 /* We now have the lower 8 Meg mapped into TLB entries, and the caches
110 ori r0,r0,MSR_DR|MSR_IR
113 ori r0,r0,start_here@l
116 rfi /* enables MMU */
119 * Exception entry code. This code runs with address translation
120 * turned off, i.e. using physical addresses.
121 * We assume sprg3 has the physical address of the current
122 * task's thread_struct.
124 #define EXCEPTION_PROLOG \
125 EXCEPTION_PROLOG_0; \
126 EXCEPTION_PROLOG_1; \
129 #define EXCEPTION_PROLOG_0 \
130 mtspr SPRN_SPRG_SCRATCH0,r10; \
131 mtspr SPRN_SPRG_SCRATCH1,r11; \
134 #define EXCEPTION_PROLOG_1 \
135 mfspr r11,SPRN_SRR1; /* check whether user or kernel */ \
136 andi. r11,r11,MSR_PR; \
137 tophys(r11,r1); /* use tophys(r1) if kernel */ \
139 mfspr r11,SPRN_SPRG_THREAD; \
140 lwz r11,THREAD_INFO-THREAD(r11); \
141 addi r11,r11,THREAD_SIZE; \
143 1: subi r11,r11,INT_FRAME_SIZE /* alloc exc. frame */
146 #define EXCEPTION_PROLOG_2 \
148 stw r10,_CCR(r11); /* save registers */ \
149 stw r12,GPR12(r11); \
151 mfspr r10,SPRN_SPRG_SCRATCH0; \
152 stw r10,GPR10(r11); \
153 mfspr r12,SPRN_SPRG_SCRATCH1; \
154 stw r12,GPR11(r11); \
156 stw r10,_LINK(r11); \
157 mfspr r12,SPRN_SRR0; \
158 mfspr r9,SPRN_SRR1; \
161 tovirt(r1,r11); /* set new kernel sp */ \
162 li r10,MSR_KERNEL & ~(MSR_IR|MSR_DR); /* can take exceptions */ \
163 MTMSRD(r10); /* (except for mach check in rtas) */ \
165 SAVE_4GPRS(3, r11); \
169 * Exception exit code.
171 #define EXCEPTION_EPILOG_0 \
173 mfspr r10,SPRN_SPRG_SCRATCH0; \
174 mfspr r11,SPRN_SPRG_SCRATCH1
177 * Note: code which follows this uses cr0.eq (set if from kernel),
178 * r11, r12 (SRR0), and r9 (SRR1).
180 * Note2: once we have set r1 we are in a position to take exceptions
181 * again, and we could thus set MSR:RI at that point.
187 #define EXCEPTION(n, label, hdlr, xfer) \
191 addi r3,r1,STACK_FRAME_OVERHEAD; \
194 #define EXC_XFER_TEMPLATE(n, hdlr, trap, copyee, tfer, ret) \
196 stw r10,_TRAP(r11); \
204 #define COPY_EE(d, s) rlwimi d,s,0,16,16
207 #define EXC_XFER_STD(n, hdlr) \
208 EXC_XFER_TEMPLATE(n, hdlr, n, NOCOPY, transfer_to_handler_full, \
209 ret_from_except_full)
211 #define EXC_XFER_LITE(n, hdlr) \
212 EXC_XFER_TEMPLATE(n, hdlr, n+1, NOCOPY, transfer_to_handler, \
215 #define EXC_XFER_EE(n, hdlr) \
216 EXC_XFER_TEMPLATE(n, hdlr, n, COPY_EE, transfer_to_handler_full, \
217 ret_from_except_full)
219 #define EXC_XFER_EE_LITE(n, hdlr) \
220 EXC_XFER_TEMPLATE(n, hdlr, n+1, COPY_EE, transfer_to_handler, \
224 EXCEPTION(0x100, Reset, unknown_exception, EXC_XFER_STD)
233 mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */
236 addi r3,r1,STACK_FRAME_OVERHEAD
237 EXC_XFER_STD(0x200, machine_check_exception)
239 /* Data access exception.
240 * This is "never generated" by the MPC8xx.
245 /* Instruction access exception.
246 * This is "never generated" by the MPC8xx.
251 /* External interrupt */
252 EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
254 /* Alignment exception */
261 mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */
264 addi r3,r1,STACK_FRAME_OVERHEAD
265 EXC_XFER_EE(0x600, alignment_exception)
267 /* Program check exception */
268 EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)
270 /* No FPU on MPC8xx. This exception is not supposed to happen.
272 EXCEPTION(0x800, FPUnavailable, unknown_exception, EXC_XFER_STD)
275 EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE)
277 EXCEPTION(0xa00, Trap_0a, unknown_exception, EXC_XFER_EE)
278 EXCEPTION(0xb00, Trap_0b, unknown_exception, EXC_XFER_EE)
284 EXC_XFER_EE_LITE(0xc00, DoSyscall)
286 /* Single step - not used on 601 */
287 EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)
288 EXCEPTION(0xe00, Trap_0e, unknown_exception, EXC_XFER_EE)
289 EXCEPTION(0xf00, Trap_0f, unknown_exception, EXC_XFER_EE)
291 /* On the MPC8xx, this is a software emulation interrupt. It occurs
292 * for all unimplemented and illegal instructions.
294 EXCEPTION(0x1000, SoftEmu, SoftwareEmulation, EXC_XFER_STD)
298 * For the MPC8xx, this is a software tablewalk to load the instruction
299 * TLB. The task switch loads the M_TW register with the pointer to the first
301 * If we discover there is no second level table (value is zero) or if there
302 * is an invalid pte, we load that into the TLB, which causes another fault
303 * into the TLB Error interrupt where we can handle such problems.
304 * We have to use the MD_xxx registers for the tablewalk because the
305 * equivalent MI_xxx registers only perform the attribute functions.
308 #ifdef CONFIG_8xx_CPU6
312 mtspr SPRN_SPRG_SCRATCH2, r10
313 mfspr r10, SPRN_SRR0 /* Get effective address of fault */
314 #ifdef CONFIG_8xx_CPU15
315 addi r11, r10, PAGE_SIZE
317 addi r11, r10, -PAGE_SIZE
321 /* If we are faulting a kernel address, we have to use the
322 * kernel page tables.
324 #ifdef CONFIG_MODULES
325 /* Only modules will cause ITLB Misses as we always
326 * pin the first 8MB of kernel memory */
327 andis. r11, r10, 0x8000 /* Address >= 0x80000000 */
329 mfspr r11, SPRN_M_TW /* Get level 1 table base address */
330 #ifdef CONFIG_MODULES
332 lis r11, (swapper_pg_dir-PAGE_OFFSET)@h
333 ori r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l
336 /* Extract level 1 index */
337 rlwinm r10, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
338 lwzx r11, r10, r11 /* Get the level 1 entry */
339 rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */
340 beq 2f /* If zero, don't try to find a pte */
342 /* We have a pte table, so load the MI_TWC with the attributes
343 * for this "segment."
345 MTSPR_CPU6(SPRN_MI_TWC, r11, r3) /* Set segment attributes */
346 mfspr r11, SPRN_SRR0 /* Get effective address of fault */
347 /* Extract level 2 index */
348 rlwinm r11, r11, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
349 lwzx r10, r10, r11 /* Get the pte */
352 andi. r11, r10, _PAGE_ACCESSED | _PAGE_PRESENT
353 cmpwi cr0, r11, _PAGE_ACCESSED | _PAGE_PRESENT
356 /* The Linux PTE won't go exactly into the MMU TLB.
357 * Software indicator bits 21 and 28 must be clear.
358 * Software indicator bits 24, 25, 26, and 27 must be
359 * set. All other Linux PTE bits control the behavior
363 rlwimi r10, r11, 0, 0x07f8 /* Set 24-27, clear 21-23,28 */
364 MTSPR_CPU6(SPRN_MI_RPN, r10, r3) /* Update TLB entry */
366 /* Restore registers */
367 #ifdef CONFIG_8xx_CPU6
370 mfspr r10, SPRN_SPRG_SCRATCH2
375 /* clear all error bits as TLB Miss
376 * sets a few unconditionally
378 rlwinm r11, r11, 0, 0xffff
381 /* Restore registers */
382 #ifdef CONFIG_8xx_CPU6
385 mfspr r10, SPRN_SPRG_SCRATCH2
387 b InstructionTLBError
391 #ifdef CONFIG_8xx_CPU6
395 mtspr SPRN_SPRG_SCRATCH2, r10
396 mfspr r10, SPRN_MD_EPN
398 /* If we are faulting a kernel address, we have to use the
399 * kernel page tables.
401 andis. r11, r10, 0x8000
402 mfspr r11, SPRN_M_TW /* Get level 1 table base address */
404 lis r11, (swapper_pg_dir-PAGE_OFFSET)@h
405 ori r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l
407 /* Extract level 1 index */
408 rlwinm r10, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
409 lwzx r11, r10, r11 /* Get the level 1 entry */
410 rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */
411 beq 2f /* If zero, don't try to find a pte */
413 /* We have a pte table, so load fetch the pte from the table.
415 mfspr r10, SPRN_MD_EPN /* Get address of fault */
416 /* Extract level 2 index */
417 rlwinm r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
418 rlwimi r10, r11, 0, 0, 32 - PAGE_SHIFT - 1 /* Add level 2 base */
419 lwz r10, 0(r10) /* Get the pte */
421 /* Insert the Guarded flag into the TWC from the Linux PTE.
422 * It is bit 27 of both the Linux PTE and the TWC (at least
423 * I got that right :-). It will be better when we can put
424 * this into the Linux pgd/pmd and load it in the operation
427 rlwimi r11, r10, 0, 27, 27
428 /* Insert the WriteThru flag into the TWC from the Linux PTE.
429 * It is bit 25 in the Linux PTE and bit 30 in the TWC
431 rlwimi r11, r10, 32-5, 30, 30
432 MTSPR_CPU6(SPRN_MD_TWC, r11, r3)
434 /* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
435 * We also need to know if the insn is a load/store, so:
436 * Clear _PAGE_PRESENT and load that which will
437 * trap into DTLB Error with store bit set accordinly.
439 /* PRESENT=0x1, ACCESSED=0x20
440 * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5));
441 * r10 = (r10 & ~PRESENT) | r11;
444 rlwinm r11, r10, 32-5, _PAGE_PRESENT
446 rlwimi r10, r11, 0, _PAGE_PRESENT
449 xori r10, r10, _PAGE_RW
451 /* The Linux PTE won't go exactly into the MMU TLB.
452 * Software indicator bits 22 and 28 must be clear.
453 * Software indicator bits 24, 25, 26, and 27 must be
454 * set. All other Linux PTE bits control the behavior
457 2: li r11, RPN_PATTERN
458 rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */
459 MTSPR_CPU6(SPRN_MD_RPN, r10, r3) /* Update TLB entry */
461 /* Restore registers */
462 #ifdef CONFIG_8xx_CPU6
465 mtspr SPRN_DAR, r11 /* Tag DAR */
466 mfspr r10, SPRN_SPRG_SCRATCH2
470 /* This is an instruction TLB error on the MPC8xx. This could be due
471 * to many reasons, such as executing guarded memory or illegal instruction
472 * addresses. There is nothing to do but handle a big time error fault.
479 /* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
480 EXC_XFER_LITE(0x400, handle_page_fault)
482 /* This is the data TLB error on the MPC8xx. This could be due to
483 * many reasons, including a dirty update to a pte. We bail out to
484 * a higher level function that can handle it.
491 cmpwi cr0, r11, RPN_PATTERN
492 beq- FixupDAR /* must be a buggy dcbX, icbi insn. */
493 DARFixed:/* Return from dcbx instruction bug workaround */
501 mtspr SPRN_DAR,r10 /* Tag DAR, to be used in DTLB Error */
502 /* 0x300 is DataAccess exception, needed by bad_page_fault() */
503 EXC_XFER_LITE(0x300, handle_page_fault)
505 EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
506 EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
507 EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE)
508 EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_EE)
509 EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_EE)
510 EXCEPTION(0x1a00, Trap_1a, unknown_exception, EXC_XFER_EE)
511 EXCEPTION(0x1b00, Trap_1b, unknown_exception, EXC_XFER_EE)
513 /* On the MPC8xx, these next four traps are used for development
514 * support of breakpoints and such. Someday I will get around to
517 EXCEPTION(0x1c00, Trap_1c, unknown_exception, EXC_XFER_EE)
518 EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_EE)
519 EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_EE)
520 EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_EE)
524 /* This is the procedure to calculate the data EA for buggy dcbx,dcbi instructions
525 * by decoding the registers used by the dcbx instruction and adding them.
526 * DAR is set to the calculated address.
528 /* define if you don't want to use self modifying code */
529 #define NO_SELF_MODIFYING_CODE
530 FixupDAR:/* Entry point for dcbx workaround. */
531 #ifdef CONFIG_8xx_CPU6
534 mtspr SPRN_SPRG_SCRATCH2, r10
535 /* fetch instruction from memory. */
537 andis. r11, r10, 0x8000 /* Address >= 0x80000000 */
538 mfspr r11, SPRN_M_TW /* Get level 1 table base address */
539 beq- 3f /* Branch if user space */
540 lis r11, (swapper_pg_dir-PAGE_OFFSET)@h
541 ori r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l
542 /* Extract level 1 index */
543 3: rlwinm r10, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
544 lwzx r11, r10, r11 /* Get the level 1 entry */
545 rlwinm r10, r11,0,0,19 /* Extract page descriptor page address */
546 mfspr r11, SPRN_SRR0 /* Get effective address of fault */
547 /* Extract level 2 index */
548 rlwinm r11, r11, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
549 lwzx r11, r10, r11 /* Get the pte */
550 #ifdef CONFIG_8xx_CPU6
551 lwz r3, 8(r0) /* restore r3 from memory */
553 /* concat physical page address(r11) and page offset(r10) */
555 rlwimi r11, r10, 0, 32 - PAGE_SHIFT, 31
557 /* Check if it really is a dcbx instruction. */
558 /* dcbt and dcbtst does not generate DTLB Misses/Errors,
559 * no need to include them here */
560 xoris r10, r11, 0x7c00 /* check if major OP code is 31 */
561 rlwinm r10, r10, 0, 21, 5
562 cmpwi cr0, r10, 2028 /* Is dcbz? */
564 cmpwi cr0, r10, 940 /* Is dcbi? */
566 cmpwi cr0, r10, 108 /* Is dcbst? */
567 beq+ 144f /* Fix up store bit! */
568 cmpwi cr0, r10, 172 /* Is dcbf? */
570 cmpwi cr0, r10, 1964 /* Is icbi? */
572 141: mfspr r10,SPRN_SPRG_SCRATCH2
573 b DARFixed /* Nope, go back to normal TLB processing */
575 144: mfspr r10, SPRN_DSISR
576 rlwinm r10, r10,0,7,5 /* Clear store bit for buggy dcbst insn */
577 mtspr SPRN_DSISR, r10
578 142: /* continue, it was a dcbx, dcbi instruction. */
579 #ifndef NO_SELF_MODIFYING_CODE
580 andis. r10,r11,0x1f /* test if reg RA is r0 */
581 li r10,modified_instr@l
582 dcbtst r0,r10 /* touch for store */
583 rlwinm r11,r11,0,0,20 /* Zero lower 10 bits */
584 oris r11,r11,640 /* Transform instr. to a "add r10,RA,RB" */
586 stw r11,0(r10) /* store add/and instruction */
587 dcbf 0,r10 /* flush new instr. to memory. */
588 icbi 0,r10 /* invalidate instr. cache line */
589 mfspr r11, SPRN_SPRG_SCRATCH1 /* restore r11 */
590 mfspr r10, SPRN_SPRG_SCRATCH0 /* restore r10 */
591 isync /* Wait until new instr is loaded from memory */
593 .space 4 /* this is where the add instr. is stored */
595 subf r10,r0,r10 /* r10=r10-r0, only if reg RA is r0 */
596 143: mtdar r10 /* store faulting EA in DAR */
597 mfspr r10,SPRN_SPRG_SCRATCH2
598 b DARFixed /* Go back to normal TLB handling */
601 mtdar r10 /* save ctr reg in DAR */
602 rlwinm r10, r11, 24, 24, 28 /* offset into jump table for reg RB */
603 addi r10, r10, 150f@l /* add start of table */
604 mtctr r10 /* load ctr with jump address */
605 xor r10, r10, r10 /* sum starts at zero */
606 bctr /* jump into table */
608 add r10, r10, r0 ;b 151f
609 add r10, r10, r1 ;b 151f
610 add r10, r10, r2 ;b 151f
611 add r10, r10, r3 ;b 151f
612 add r10, r10, r4 ;b 151f
613 add r10, r10, r5 ;b 151f
614 add r10, r10, r6 ;b 151f
615 add r10, r10, r7 ;b 151f
616 add r10, r10, r8 ;b 151f
617 add r10, r10, r9 ;b 151f
618 mtctr r11 ;b 154f /* r10 needs special handling */
619 mtctr r11 ;b 153f /* r11 needs special handling */
620 add r10, r10, r12 ;b 151f
621 add r10, r10, r13 ;b 151f
622 add r10, r10, r14 ;b 151f
623 add r10, r10, r15 ;b 151f
624 add r10, r10, r16 ;b 151f
625 add r10, r10, r17 ;b 151f
626 add r10, r10, r18 ;b 151f
627 add r10, r10, r19 ;b 151f
628 add r10, r10, r20 ;b 151f
629 add r10, r10, r21 ;b 151f
630 add r10, r10, r22 ;b 151f
631 add r10, r10, r23 ;b 151f
632 add r10, r10, r24 ;b 151f
633 add r10, r10, r25 ;b 151f
634 add r10, r10, r26 ;b 151f
635 add r10, r10, r27 ;b 151f
636 add r10, r10, r28 ;b 151f
637 add r10, r10, r29 ;b 151f
638 add r10, r10, r30 ;b 151f
641 rlwinm. r11,r11,19,24,28 /* offset into jump table for reg RA */
642 beq 152f /* if reg RA is zero, don't add it */
643 addi r11, r11, 150b@l /* add start of table */
644 mtctr r11 /* load ctr with jump address */
645 rlwinm r11,r11,0,16,10 /* make sure we don't execute this more than once */
646 bctr /* jump into table */
649 mtctr r11 /* restore ctr reg from DAR */
650 mtdar r10 /* save fault EA to DAR */
651 mfspr r10,SPRN_SPRG_SCRATCH2
652 b DARFixed /* Go back to normal TLB handling */
654 /* special handling for r10,r11 since these are modified already */
655 153: mfspr r11, SPRN_SPRG_SCRATCH1 /* load r11 from SPRN_SPRG_SCRATCH1 */
656 add r10, r10, r11 /* add it */
657 mfctr r11 /* restore r11 */
659 154: mfspr r11, SPRN_SPRG_SCRATCH0 /* load r10 from SPRN_SPRG_SCRATCH0 */
660 add r10, r10, r11 /* add it */
661 mfctr r11 /* restore r11 */
666 * This is where the main kernel code starts.
671 ori r2,r2,init_task@l
673 /* ptr to phys current thread */
675 addi r4,r4,THREAD /* init task's THREAD */
676 mtspr SPRN_SPRG_THREAD,r4
679 lis r1,init_thread_union@ha
680 addi r1,r1,init_thread_union@l
682 stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
684 bl early_init /* We have to do this with MMU on */
687 * Decide what sort of machine this is and initialize the MMU.
695 * Go back to running unmapped so we can load up new values
696 * and change to using our exception vectors.
697 * On the 8xx, all we have to do is invalidate the TLB to clear
698 * the old 8M byte TLB mappings and load the page table base register.
700 /* The right way to do this would be to track it down through
701 * init's THREAD like the context switch code does, but this is
702 * easier......until someone changes init's static structures.
704 lis r6, swapper_pg_dir@h
705 ori r6, r6, swapper_pg_dir@l
707 #ifdef CONFIG_8xx_CPU6
708 lis r4, cpu6_errata_word@h
709 ori r4, r4, cpu6_errata_word@l
718 li r3,MSR_KERNEL & ~(MSR_IR|MSR_DR)
722 /* Load up the kernel context */
724 SYNC /* Force all PTE updates to finish */
725 tlbia /* Clear all TLB entries */
726 sync /* wait for tlbia/tlbie to finish */
727 TLBSYNC /* ... on all CPUs */
729 /* set up the PTE pointers for the Abatron bdiGDB.
732 lis r5, abatron_pteptrs@h
733 ori r5, r5, abatron_pteptrs@l
734 stw r5, 0xf0(r0) /* Must match your Abatron config file */
738 /* Now turn on the MMU for real! */
740 lis r3,start_kernel@h
741 ori r3,r3,start_kernel@l
744 rfi /* enable MMU and jump to start_kernel */
746 /* Set up the initial MMU state so we can do the first level of
747 * kernel initialization. This maps the first 8 MBytes of memory 1:1
748 * virtual to physical. Also, set the cache mode since that is defined
749 * by TLB entries and perform any additional mapping (like of the IMMR).
750 * If configured to pin some TLBs, we pin the first 8 Mbytes of kernel,
751 * 24 Mbytes of data, and the 8M IMMR space. Anything not covered by
752 * these mappings is mapped by page tables.
755 tlbia /* Invalidate all TLB entries */
756 /* Always pin the first 8 MB ITLB to prevent ITLB
757 misses while mucking around with SRR0/SRR1 in asm
762 mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
764 #ifdef CONFIG_PIN_TLB
765 lis r10, (MD_RSV4I | MD_RESETVAL)@h
769 lis r10, MD_RESETVAL@h
771 #ifndef CONFIG_8xx_COPYBACK
772 oris r10, r10, MD_WTDEF@h
774 mtspr SPRN_MD_CTR, r10 /* Set data TLB control */
776 /* Now map the lower 8 Meg into the TLBs. For this quick hack,
777 * we can load the instruction and data TLB registers with the
780 lis r8, KERNELBASE@h /* Create vaddr for TLB */
781 ori r8, r8, MI_EVALID /* Mark it valid */
782 mtspr SPRN_MI_EPN, r8
783 mtspr SPRN_MD_EPN, r8
784 li r8, MI_PS8MEG /* Set 8M byte page */
785 ori r8, r8, MI_SVALID /* Make it valid */
786 mtspr SPRN_MI_TWC, r8
787 mtspr SPRN_MD_TWC, r8
788 li r8, MI_BOOTINIT /* Create RPN for address 0 */
789 mtspr SPRN_MI_RPN, r8 /* Store TLB entry */
790 mtspr SPRN_MD_RPN, r8
791 lis r8, MI_Kp@h /* Set the protection mode */
795 /* Map another 8 MByte at the IMMR to get the processor
796 * internal registers (among other things).
798 #ifdef CONFIG_PIN_TLB
799 addi r10, r10, 0x0100
800 mtspr SPRN_MD_CTR, r10
802 mfspr r9, 638 /* Get current IMMR */
803 andis. r9, r9, 0xff80 /* Get 8Mbyte boundary */
805 mr r8, r9 /* Create vaddr for TLB */
806 ori r8, r8, MD_EVALID /* Mark it valid */
807 mtspr SPRN_MD_EPN, r8
808 li r8, MD_PS8MEG /* Set 8M byte page */
809 ori r8, r8, MD_SVALID /* Make it valid */
810 mtspr SPRN_MD_TWC, r8
811 mr r8, r9 /* Create paddr for TLB */
812 ori r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */
813 mtspr SPRN_MD_RPN, r8
815 #ifdef CONFIG_PIN_TLB
816 /* Map two more 8M kernel data pages.
818 addi r10, r10, 0x0100
819 mtspr SPRN_MD_CTR, r10
821 lis r8, KERNELBASE@h /* Create vaddr for TLB */
822 addis r8, r8, 0x0080 /* Add 8M */
823 ori r8, r8, MI_EVALID /* Mark it valid */
824 mtspr SPRN_MD_EPN, r8
825 li r9, MI_PS8MEG /* Set 8M byte page */
826 ori r9, r9, MI_SVALID /* Make it valid */
827 mtspr SPRN_MD_TWC, r9
828 li r11, MI_BOOTINIT /* Create RPN for address 0 */
829 addis r11, r11, 0x0080 /* Add 8M */
830 mtspr SPRN_MD_RPN, r11
832 addi r10, r10, 0x0100
833 mtspr SPRN_MD_CTR, r10
835 addis r8, r8, 0x0080 /* Add 8M */
836 mtspr SPRN_MD_EPN, r8
837 mtspr SPRN_MD_TWC, r9
838 addis r11, r11, 0x0080 /* Add 8M */
839 mtspr SPRN_MD_RPN, r11
842 /* Since the cache is enabled according to the information we
843 * just loaded into the TLB, invalidate and enable the caches here.
844 * We should probably check/set other modes....later.
847 mtspr SPRN_IC_CST, r8
848 mtspr SPRN_DC_CST, r8
850 mtspr SPRN_IC_CST, r8
851 #ifdef CONFIG_8xx_COPYBACK
852 mtspr SPRN_DC_CST, r8
854 /* For a debug option, I left this here to easily enable
855 * the write through cache mode
858 mtspr SPRN_DC_CST, r8
860 mtspr SPRN_DC_CST, r8
866 * Set up to use a given MMU context.
867 * r3 is context number, r4 is PGD pointer.
869 * We place the physical address of the new task page directory loaded
870 * into the MMU base register, and set the ASID compare register with
875 #ifdef CONFIG_BDI_SWITCH
876 /* Context switch the PTE pointer for the Abatron BDI2000.
877 * The PGDIR is passed as second argument.
884 #ifdef CONFIG_8xx_CPU6
885 lis r6, cpu6_errata_word@h
886 ori r6, r6, cpu6_errata_word@l
891 mtspr SPRN_M_TW, r4 /* Update MMU base address */
895 mtspr SPRN_M_CASID, r3 /* Update context */
897 mtspr SPRN_M_CASID,r3 /* Update context */
899 mtspr SPRN_M_TW, r4 /* and pgd */
904 #ifdef CONFIG_8xx_CPU6
905 /* It's here because it is unique to the 8xx.
906 * It is important we get called with interrupts disabled. I used to
907 * do that, but it appears that all code that calls this already had
908 * interrupt disabled.
912 lis r7, cpu6_errata_word@h
913 ori r7, r7, cpu6_errata_word@l
917 mtspr 22, r3 /* Update Decrementer */
923 * We put a few things here that have to be page-aligned.
924 * This stuff goes at the beginning of the data segment,
925 * which is page-aligned.
930 .globl empty_zero_page
935 .globl swapper_pg_dir
937 .space PGD_TABLE_SIZE
939 /* Room for two PTE table poiners, usually the kernel and current user
940 * pointer to their respective root page table (pgdir).
945 #ifdef CONFIG_8xx_CPU6
946 .globl cpu6_errata_word