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 DO_8xx_CPU6(val, reg) \
41 #define DO_8xx_CPU6(val, reg)
45 * Value for the bits that have fixed value in RPN entries.
46 * Also used for tagging DAR for DTLBerror.
48 #ifdef CONFIG_PPC_16K_PAGES
49 #define RPN_PATTERN (0x00f0 | MD_SPS16K)
51 #define RPN_PATTERN 0x00f0
59 * This port was done on an MBX board with an 860. Right now I only
60 * support an ELF compressed (zImage) boot from EPPC-Bug because the
61 * code there loads up some registers before calling us:
62 * r3: ptr to board info data
63 * r4: initrd_start or if no initrd then 0
64 * r5: initrd_end - unused if r4 is 0
65 * r6: Start of command line string
66 * r7: End of command line string
68 * I decided to use conditional compilation instead of checking PVR and
69 * adding more processor specific branches around code I don't need.
70 * Since this is an embedded processor, I also appreciate any memory
73 * The MPC8xx does not have any BATs, but it supports large page sizes.
74 * We first initialize the MMU to support 8M byte pages, then load one
75 * entry into each of the instruction and data TLBs to map the first
76 * 8M 1:1. I also mapped an additional I/O space 1:1 so we can get to
77 * the "internal" processor registers before MMU_init is called.
79 * The TLB code currently contains a major hack. Since I use the condition
80 * code register, I have to save and restore it. I am out of registers, so
81 * I just store it in memory location 0 (the TLB handlers are not reentrant).
82 * To avoid making any decisions, I need to use the "segment" valid bit
83 * in the first level table, but that would require many changes to the
84 * Linux page directory/table functions that I don't want to do right now.
90 mr r31,r3 /* save device tree ptr */
92 /* We have to turn on the MMU right away so we get cache modes
97 /* We now have the lower 8 Meg mapped into TLB entries, and the caches
103 ori r0,r0,MSR_DR|MSR_IR
106 ori r0,r0,start_here@l
109 rfi /* enables MMU */
112 * Exception entry code. This code runs with address translation
113 * turned off, i.e. using physical addresses.
114 * We assume sprg3 has the physical address of the current
115 * task's thread_struct.
117 #define EXCEPTION_PROLOG \
118 EXCEPTION_PROLOG_0; \
119 EXCEPTION_PROLOG_1; \
122 #define EXCEPTION_PROLOG_0 \
123 mtspr SPRN_SPRG_SCRATCH0,r10; \
124 mtspr SPRN_SPRG_SCRATCH1,r11; \
127 #define EXCEPTION_PROLOG_1 \
128 mfspr r11,SPRN_SRR1; /* check whether user or kernel */ \
129 andi. r11,r11,MSR_PR; \
130 tophys(r11,r1); /* use tophys(r1) if kernel */ \
132 mfspr r11,SPRN_SPRG_THREAD; \
133 lwz r11,THREAD_INFO-THREAD(r11); \
134 addi r11,r11,THREAD_SIZE; \
136 1: subi r11,r11,INT_FRAME_SIZE /* alloc exc. frame */
139 #define EXCEPTION_PROLOG_2 \
141 stw r10,_CCR(r11); /* save registers */ \
142 stw r12,GPR12(r11); \
144 mfspr r10,SPRN_SPRG_SCRATCH0; \
145 stw r10,GPR10(r11); \
146 mfspr r12,SPRN_SPRG_SCRATCH1; \
147 stw r12,GPR11(r11); \
149 stw r10,_LINK(r11); \
150 mfspr r12,SPRN_SRR0; \
151 mfspr r9,SPRN_SRR1; \
154 tovirt(r1,r11); /* set new kernel sp */ \
155 li r10,MSR_KERNEL & ~(MSR_IR|MSR_DR); /* can take exceptions */ \
156 MTMSRD(r10); /* (except for mach check in rtas) */ \
158 SAVE_4GPRS(3, r11); \
162 * Exception exit code.
164 #define EXCEPTION_EPILOG_0 \
166 mfspr r10,SPRN_SPRG_SCRATCH0; \
167 mfspr r11,SPRN_SPRG_SCRATCH1
170 * Note: code which follows this uses cr0.eq (set if from kernel),
171 * r11, r12 (SRR0), and r9 (SRR1).
173 * Note2: once we have set r1 we are in a position to take exceptions
174 * again, and we could thus set MSR:RI at that point.
180 #define EXCEPTION(n, label, hdlr, xfer) \
184 addi r3,r1,STACK_FRAME_OVERHEAD; \
187 #define EXC_XFER_TEMPLATE(n, hdlr, trap, copyee, tfer, ret) \
189 stw r10,_TRAP(r11); \
197 #define COPY_EE(d, s) rlwimi d,s,0,16,16
200 #define EXC_XFER_STD(n, hdlr) \
201 EXC_XFER_TEMPLATE(n, hdlr, n, NOCOPY, transfer_to_handler_full, \
202 ret_from_except_full)
204 #define EXC_XFER_LITE(n, hdlr) \
205 EXC_XFER_TEMPLATE(n, hdlr, n+1, NOCOPY, transfer_to_handler, \
208 #define EXC_XFER_EE(n, hdlr) \
209 EXC_XFER_TEMPLATE(n, hdlr, n, COPY_EE, transfer_to_handler_full, \
210 ret_from_except_full)
212 #define EXC_XFER_EE_LITE(n, hdlr) \
213 EXC_XFER_TEMPLATE(n, hdlr, n+1, COPY_EE, transfer_to_handler, \
217 EXCEPTION(0x100, Reset, unknown_exception, EXC_XFER_STD)
226 mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */
229 addi r3,r1,STACK_FRAME_OVERHEAD
230 EXC_XFER_STD(0x200, machine_check_exception)
232 /* Data access exception.
233 * This is "never generated" by the MPC8xx.
238 /* Instruction access exception.
239 * This is "never generated" by the MPC8xx.
244 /* External interrupt */
245 EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
247 /* Alignment exception */
254 mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */
257 addi r3,r1,STACK_FRAME_OVERHEAD
258 EXC_XFER_EE(0x600, alignment_exception)
260 /* Program check exception */
261 EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)
263 /* No FPU on MPC8xx. This exception is not supposed to happen.
265 EXCEPTION(0x800, FPUnavailable, unknown_exception, EXC_XFER_STD)
268 EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE)
270 EXCEPTION(0xa00, Trap_0a, unknown_exception, EXC_XFER_EE)
271 EXCEPTION(0xb00, Trap_0b, unknown_exception, EXC_XFER_EE)
277 EXC_XFER_EE_LITE(0xc00, DoSyscall)
279 /* Single step - not used on 601 */
280 EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)
281 EXCEPTION(0xe00, Trap_0e, unknown_exception, EXC_XFER_EE)
282 EXCEPTION(0xf00, Trap_0f, unknown_exception, EXC_XFER_EE)
284 /* On the MPC8xx, this is a software emulation interrupt. It occurs
285 * for all unimplemented and illegal instructions.
287 EXCEPTION(0x1000, SoftEmu, SoftwareEmulation, EXC_XFER_STD)
291 * For the MPC8xx, this is a software tablewalk to load the instruction
292 * TLB. The task switch loads the M_TW register with the pointer to the first
294 * If we discover there is no second level table (value is zero) or if there
295 * is an invalid pte, we load that into the TLB, which causes another fault
296 * into the TLB Error interrupt where we can handle such problems.
297 * We have to use the MD_xxx registers for the tablewalk because the
298 * equivalent MI_xxx registers only perform the attribute functions.
301 #ifdef CONFIG_8xx_CPU6
305 mtspr SPRN_SPRG_SCRATCH2, r10
306 mfspr r10, SPRN_SRR0 /* Get effective address of fault */
307 #ifdef CONFIG_8xx_CPU15
308 addi r11, r10, PAGE_SIZE
310 addi r11, r10, -PAGE_SIZE
314 /* If we are faulting a kernel address, we have to use the
315 * kernel page tables.
317 #ifdef CONFIG_MODULES
318 /* Only modules will cause ITLB Misses as we always
319 * pin the first 8MB of kernel memory */
320 andis. r11, r10, 0x8000 /* Address >= 0x80000000 */
322 mfspr r11, SPRN_M_TW /* Get level 1 table base address */
323 #ifdef CONFIG_MODULES
325 lis r11, (swapper_pg_dir-PAGE_OFFSET)@h
326 ori r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l
329 /* Extract level 1 index */
330 rlwinm r10, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
331 lwzx r11, r10, r11 /* Get the level 1 entry */
332 rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */
333 beq 2f /* If zero, don't try to find a pte */
335 /* We have a pte table, so load the MI_TWC with the attributes
336 * for this "segment."
338 ori r11,r11,1 /* Set valid bit */
339 DO_8xx_CPU6(0x2b80, r3)
340 mtspr SPRN_MI_TWC, r11 /* Set segment attributes */
341 mfspr r11, SPRN_SRR0 /* Get effective address of fault */
342 /* Extract level 2 index */
343 rlwinm r11, r11, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
344 lwzx r10, r10, r11 /* Get the pte */
347 andi. r11, r10, _PAGE_ACCESSED | _PAGE_PRESENT
348 cmpwi cr0, r11, _PAGE_ACCESSED | _PAGE_PRESENT
351 /* The Linux PTE won't go exactly into the MMU TLB.
352 * Software indicator bits 21 and 28 must be clear.
353 * Software indicator bits 24, 25, 26, and 27 must be
354 * set. All other Linux PTE bits control the behavior
358 rlwimi r10, r11, 0, 0x07f8 /* Set 24-27, clear 21-23,28 */
359 DO_8xx_CPU6(0x2d80, r3)
360 mtspr SPRN_MI_RPN, r10 /* Update TLB entry */
362 /* Restore registers */
363 #ifdef CONFIG_8xx_CPU6
366 mfspr r10, SPRN_SPRG_SCRATCH2
371 /* clear all error bits as TLB Miss
372 * sets a few unconditionally
374 rlwinm r11, r11, 0, 0xffff
377 /* Restore registers */
378 #ifdef CONFIG_8xx_CPU6
381 mfspr r10, SPRN_SPRG_SCRATCH2
383 b InstructionTLBError
387 #ifdef CONFIG_8xx_CPU6
391 mtspr SPRN_SPRG_SCRATCH2, r10
392 mfspr r10, SPRN_MD_EPN
394 /* If we are faulting a kernel address, we have to use the
395 * kernel page tables.
397 andis. r11, r10, 0x8000
398 mfspr r11, SPRN_M_TW /* Get level 1 table base address */
400 lis r11, (swapper_pg_dir-PAGE_OFFSET)@h
401 ori r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l
403 /* Extract level 1 index */
404 rlwinm r10, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
405 lwzx r11, r10, r11 /* Get the level 1 entry */
406 rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */
407 beq 2f /* If zero, don't try to find a pte */
409 /* We have a pte table, so load fetch the pte from the table.
411 mfspr r10, SPRN_MD_EPN /* Get address of fault */
412 /* Extract level 2 index */
413 rlwinm r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
414 rlwimi r10, r11, 0, 0, 32 - PAGE_SHIFT - 1 /* Add level 2 base */
415 lwz r10, 0(r10) /* Get the pte */
417 ori r11, r11, 1 /* Set valid bit in physical L2 page */
418 /* Insert the Guarded flag into the TWC from the Linux PTE.
419 * It is bit 27 of both the Linux PTE and the TWC (at least
420 * I got that right :-). It will be better when we can put
421 * this into the Linux pgd/pmd and load it in the operation
424 rlwimi r11, r10, 0, 27, 27
425 /* Insert the WriteThru flag into the TWC from the Linux PTE.
426 * It is bit 25 in the Linux PTE and bit 30 in the TWC
428 rlwimi r11, r10, 32-5, 30, 30
429 DO_8xx_CPU6(0x3b80, r3)
430 mtspr SPRN_MD_TWC, r11
432 /* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
433 * We also need to know if the insn is a load/store, so:
434 * Clear _PAGE_PRESENT and load that which will
435 * trap into DTLB Error with store bit set accordinly.
437 /* PRESENT=0x1, ACCESSED=0x20
438 * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5));
439 * r10 = (r10 & ~PRESENT) | r11;
442 rlwinm r11, r10, 32-5, _PAGE_PRESENT
444 rlwimi r10, r11, 0, _PAGE_PRESENT
446 /* Honour kernel RO, User NA */
447 /* 0x200 == Extended encoding, bit 22 */
448 rlwimi r10, r10, 32-2, 0x200 /* Copy USER to bit 22, 0x200 */
449 /* r11 = (r10 & _PAGE_RW) >> 1 */
450 rlwinm r11, r10, 32-1, 0x200
452 /* invert RW and 0x200 bits */
453 xori r10, r10, _PAGE_RW | 0x200
455 /* The Linux PTE won't go exactly into the MMU TLB.
456 * Software indicator bits 22 and 28 must be clear.
457 * Software indicator bits 24, 25, 26, and 27 must be
458 * set. All other Linux PTE bits control the behavior
461 2: li r11, RPN_PATTERN
462 rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */
463 DO_8xx_CPU6(0x3d80, r3)
464 mtspr SPRN_MD_RPN, r10 /* Update TLB entry */
466 /* Restore registers */
467 #ifdef CONFIG_8xx_CPU6
470 mtspr SPRN_DAR, r11 /* Tag DAR */
471 mfspr r10, SPRN_SPRG_SCRATCH2
475 /* This is an instruction TLB error on the MPC8xx. This could be due
476 * to many reasons, such as executing guarded memory or illegal instruction
477 * addresses. There is nothing to do but handle a big time error fault.
484 /* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
485 EXC_XFER_LITE(0x400, handle_page_fault)
487 /* This is the data TLB error on the MPC8xx. This could be due to
488 * many reasons, including a dirty update to a pte. We bail out to
489 * a higher level function that can handle it.
496 cmpwi cr0, r11, RPN_PATTERN
497 beq- FixupDAR /* must be a buggy dcbX, icbi insn. */
498 DARFixed:/* Return from dcbx instruction bug workaround */
506 mtspr SPRN_DAR,r10 /* Tag DAR, to be used in DTLB Error */
507 /* 0x300 is DataAccess exception, needed by bad_page_fault() */
508 EXC_XFER_LITE(0x300, handle_page_fault)
510 EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
511 EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
512 EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE)
513 EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_EE)
514 EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_EE)
515 EXCEPTION(0x1a00, Trap_1a, unknown_exception, EXC_XFER_EE)
516 EXCEPTION(0x1b00, Trap_1b, unknown_exception, EXC_XFER_EE)
518 /* On the MPC8xx, these next four traps are used for development
519 * support of breakpoints and such. Someday I will get around to
522 EXCEPTION(0x1c00, Trap_1c, unknown_exception, EXC_XFER_EE)
523 EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_EE)
524 EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_EE)
525 EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_EE)
529 /* This is the procedure to calculate the data EA for buggy dcbx,dcbi instructions
530 * by decoding the registers used by the dcbx instruction and adding them.
531 * DAR is set to the calculated address.
533 /* define if you don't want to use self modifying code */
534 #define NO_SELF_MODIFYING_CODE
535 FixupDAR:/* Entry point for dcbx workaround. */
536 #ifdef CONFIG_8xx_CPU6
539 mtspr SPRN_SPRG_SCRATCH2, r10
540 /* fetch instruction from memory. */
542 andis. r11, r10, 0x8000 /* Address >= 0x80000000 */
543 mfspr r11, SPRN_M_TW /* Get level 1 table base address */
544 beq- 3f /* Branch if user space */
545 lis r11, (swapper_pg_dir-PAGE_OFFSET)@h
546 ori r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l
547 /* Extract level 1 index */
548 3: rlwinm r10, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
549 lwzx r11, r10, r11 /* Get the level 1 entry */
550 rlwinm r10, r11,0,0,19 /* Extract page descriptor page address */
551 mfspr r11, SPRN_SRR0 /* Get effective address of fault */
552 /* Extract level 2 index */
553 rlwinm r11, r11, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
554 lwzx r11, r10, r11 /* Get the pte */
555 #ifdef CONFIG_8xx_CPU6
556 lwz r3, 8(r0) /* restore r3 from memory */
558 /* concat physical page address(r11) and page offset(r10) */
560 rlwimi r11, r10, 0, 32 - PAGE_SHIFT, 31
562 /* Check if it really is a dcbx instruction. */
563 /* dcbt and dcbtst does not generate DTLB Misses/Errors,
564 * no need to include them here */
565 xoris r10, r11, 0x7c00 /* check if major OP code is 31 */
566 rlwinm r10, r10, 0, 21, 5
567 cmpwi cr0, r10, 2028 /* Is dcbz? */
569 cmpwi cr0, r10, 940 /* Is dcbi? */
571 cmpwi cr0, r10, 108 /* Is dcbst? */
572 beq+ 144f /* Fix up store bit! */
573 cmpwi cr0, r10, 172 /* Is dcbf? */
575 cmpwi cr0, r10, 1964 /* Is icbi? */
577 141: mfspr r10,SPRN_SPRG_SCRATCH2
578 b DARFixed /* Nope, go back to normal TLB processing */
580 144: mfspr r10, SPRN_DSISR
581 rlwinm r10, r10,0,7,5 /* Clear store bit for buggy dcbst insn */
582 mtspr SPRN_DSISR, r10
583 142: /* continue, it was a dcbx, dcbi instruction. */
584 #ifndef NO_SELF_MODIFYING_CODE
585 andis. r10,r11,0x1f /* test if reg RA is r0 */
586 li r10,modified_instr@l
587 dcbtst r0,r10 /* touch for store */
588 rlwinm r11,r11,0,0,20 /* Zero lower 10 bits */
589 oris r11,r11,640 /* Transform instr. to a "add r10,RA,RB" */
591 stw r11,0(r10) /* store add/and instruction */
592 dcbf 0,r10 /* flush new instr. to memory. */
593 icbi 0,r10 /* invalidate instr. cache line */
594 mfspr r11, SPRN_SPRG_SCRATCH1 /* restore r11 */
595 mfspr r10, SPRN_SPRG_SCRATCH0 /* restore r10 */
596 isync /* Wait until new instr is loaded from memory */
598 .space 4 /* this is where the add instr. is stored */
600 subf r10,r0,r10 /* r10=r10-r0, only if reg RA is r0 */
601 143: mtdar r10 /* store faulting EA in DAR */
602 mfspr r10,SPRN_SPRG_SCRATCH2
603 b DARFixed /* Go back to normal TLB handling */
606 mtdar r10 /* save ctr reg in DAR */
607 rlwinm r10, r11, 24, 24, 28 /* offset into jump table for reg RB */
608 addi r10, r10, 150f@l /* add start of table */
609 mtctr r10 /* load ctr with jump address */
610 xor r10, r10, r10 /* sum starts at zero */
611 bctr /* jump into table */
613 add r10, r10, r0 ;b 151f
614 add r10, r10, r1 ;b 151f
615 add r10, r10, r2 ;b 151f
616 add r10, r10, r3 ;b 151f
617 add r10, r10, r4 ;b 151f
618 add r10, r10, r5 ;b 151f
619 add r10, r10, r6 ;b 151f
620 add r10, r10, r7 ;b 151f
621 add r10, r10, r8 ;b 151f
622 add r10, r10, r9 ;b 151f
623 mtctr r11 ;b 154f /* r10 needs special handling */
624 mtctr r11 ;b 153f /* r11 needs special handling */
625 add r10, r10, r12 ;b 151f
626 add r10, r10, r13 ;b 151f
627 add r10, r10, r14 ;b 151f
628 add r10, r10, r15 ;b 151f
629 add r10, r10, r16 ;b 151f
630 add r10, r10, r17 ;b 151f
631 add r10, r10, r18 ;b 151f
632 add r10, r10, r19 ;b 151f
633 add r10, r10, r20 ;b 151f
634 add r10, r10, r21 ;b 151f
635 add r10, r10, r22 ;b 151f
636 add r10, r10, r23 ;b 151f
637 add r10, r10, r24 ;b 151f
638 add r10, r10, r25 ;b 151f
639 add r10, r10, r26 ;b 151f
640 add r10, r10, r27 ;b 151f
641 add r10, r10, r28 ;b 151f
642 add r10, r10, r29 ;b 151f
643 add r10, r10, r30 ;b 151f
646 rlwinm. r11,r11,19,24,28 /* offset into jump table for reg RA */
647 beq 152f /* if reg RA is zero, don't add it */
648 addi r11, r11, 150b@l /* add start of table */
649 mtctr r11 /* load ctr with jump address */
650 rlwinm r11,r11,0,16,10 /* make sure we don't execute this more than once */
651 bctr /* jump into table */
654 mtctr r11 /* restore ctr reg from DAR */
655 mtdar r10 /* save fault EA to DAR */
656 mfspr r10,SPRN_SPRG_SCRATCH2
657 b DARFixed /* Go back to normal TLB handling */
659 /* special handling for r10,r11 since these are modified already */
660 153: mfspr r11, SPRN_SPRG_SCRATCH1 /* load r11 from SPRN_SPRG_SCRATCH1 */
661 add r10, r10, r11 /* add it */
662 mfctr r11 /* restore r11 */
664 154: mfspr r11, SPRN_SPRG_SCRATCH0 /* load r10 from SPRN_SPRG_SCRATCH0 */
665 add r10, r10, r11 /* add it */
666 mfctr r11 /* restore r11 */
671 * This is where the main kernel code starts.
676 ori r2,r2,init_task@l
678 /* ptr to phys current thread */
680 addi r4,r4,THREAD /* init task's THREAD */
681 mtspr SPRN_SPRG_THREAD,r4
684 lis r1,init_thread_union@ha
685 addi r1,r1,init_thread_union@l
687 stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
689 bl early_init /* We have to do this with MMU on */
692 * Decide what sort of machine this is and initialize the MMU.
700 * Go back to running unmapped so we can load up new values
701 * and change to using our exception vectors.
702 * On the 8xx, all we have to do is invalidate the TLB to clear
703 * the old 8M byte TLB mappings and load the page table base register.
705 /* The right way to do this would be to track it down through
706 * init's THREAD like the context switch code does, but this is
707 * easier......until someone changes init's static structures.
709 lis r6, swapper_pg_dir@h
710 ori r6, r6, swapper_pg_dir@l
712 #ifdef CONFIG_8xx_CPU6
713 lis r4, cpu6_errata_word@h
714 ori r4, r4, cpu6_errata_word@l
723 li r3,MSR_KERNEL & ~(MSR_IR|MSR_DR)
727 /* Load up the kernel context */
729 SYNC /* Force all PTE updates to finish */
730 tlbia /* Clear all TLB entries */
731 sync /* wait for tlbia/tlbie to finish */
732 TLBSYNC /* ... on all CPUs */
734 /* set up the PTE pointers for the Abatron bdiGDB.
737 lis r5, abatron_pteptrs@h
738 ori r5, r5, abatron_pteptrs@l
739 stw r5, 0xf0(r0) /* Must match your Abatron config file */
743 /* Now turn on the MMU for real! */
745 lis r3,start_kernel@h
746 ori r3,r3,start_kernel@l
749 rfi /* enable MMU and jump to start_kernel */
751 /* Set up the initial MMU state so we can do the first level of
752 * kernel initialization. This maps the first 8 MBytes of memory 1:1
753 * virtual to physical. Also, set the cache mode since that is defined
754 * by TLB entries and perform any additional mapping (like of the IMMR).
755 * If configured to pin some TLBs, we pin the first 8 Mbytes of kernel,
756 * 24 Mbytes of data, and the 8M IMMR space. Anything not covered by
757 * these mappings is mapped by page tables.
760 tlbia /* Invalidate all TLB entries */
761 /* Always pin the first 8 MB ITLB to prevent ITLB
762 misses while mucking around with SRR0/SRR1 in asm
767 mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
769 #ifdef CONFIG_PIN_TLB
770 lis r10, (MD_RSV4I | MD_RESETVAL)@h
774 lis r10, MD_RESETVAL@h
776 #ifndef CONFIG_8xx_COPYBACK
777 oris r10, r10, MD_WTDEF@h
779 mtspr SPRN_MD_CTR, r10 /* Set data TLB control */
781 /* Now map the lower 8 Meg into the TLBs. For this quick hack,
782 * we can load the instruction and data TLB registers with the
785 lis r8, KERNELBASE@h /* Create vaddr for TLB */
786 ori r8, r8, MI_EVALID /* Mark it valid */
787 mtspr SPRN_MI_EPN, r8
788 mtspr SPRN_MD_EPN, r8
789 li r8, MI_PS8MEG /* Set 8M byte page */
790 ori r8, r8, MI_SVALID /* Make it valid */
791 mtspr SPRN_MI_TWC, r8
792 mtspr SPRN_MD_TWC, r8
793 li r8, MI_BOOTINIT /* Create RPN for address 0 */
794 mtspr SPRN_MI_RPN, r8 /* Store TLB entry */
795 mtspr SPRN_MD_RPN, r8
796 lis r8, MI_Kp@h /* Set the protection mode */
800 /* Map another 8 MByte at the IMMR to get the processor
801 * internal registers (among other things).
803 #ifdef CONFIG_PIN_TLB
804 addi r10, r10, 0x0100
805 mtspr SPRN_MD_CTR, r10
807 mfspr r9, 638 /* Get current IMMR */
808 andis. r9, r9, 0xff80 /* Get 8Mbyte boundary */
810 mr r8, r9 /* Create vaddr for TLB */
811 ori r8, r8, MD_EVALID /* Mark it valid */
812 mtspr SPRN_MD_EPN, r8
813 li r8, MD_PS8MEG /* Set 8M byte page */
814 ori r8, r8, MD_SVALID /* Make it valid */
815 mtspr SPRN_MD_TWC, r8
816 mr r8, r9 /* Create paddr for TLB */
817 ori r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */
818 mtspr SPRN_MD_RPN, r8
820 #ifdef CONFIG_PIN_TLB
821 /* Map two more 8M kernel data pages.
823 addi r10, r10, 0x0100
824 mtspr SPRN_MD_CTR, r10
826 lis r8, KERNELBASE@h /* Create vaddr for TLB */
827 addis r8, r8, 0x0080 /* Add 8M */
828 ori r8, r8, MI_EVALID /* Mark it valid */
829 mtspr SPRN_MD_EPN, r8
830 li r9, MI_PS8MEG /* Set 8M byte page */
831 ori r9, r9, MI_SVALID /* Make it valid */
832 mtspr SPRN_MD_TWC, r9
833 li r11, MI_BOOTINIT /* Create RPN for address 0 */
834 addis r11, r11, 0x0080 /* Add 8M */
835 mtspr SPRN_MD_RPN, r11
837 addi r10, r10, 0x0100
838 mtspr SPRN_MD_CTR, r10
840 addis r8, r8, 0x0080 /* Add 8M */
841 mtspr SPRN_MD_EPN, r8
842 mtspr SPRN_MD_TWC, r9
843 addis r11, r11, 0x0080 /* Add 8M */
844 mtspr SPRN_MD_RPN, r11
847 /* Since the cache is enabled according to the information we
848 * just loaded into the TLB, invalidate and enable the caches here.
849 * We should probably check/set other modes....later.
852 mtspr SPRN_IC_CST, r8
853 mtspr SPRN_DC_CST, r8
855 mtspr SPRN_IC_CST, r8
856 #ifdef CONFIG_8xx_COPYBACK
857 mtspr SPRN_DC_CST, r8
859 /* For a debug option, I left this here to easily enable
860 * the write through cache mode
863 mtspr SPRN_DC_CST, r8
865 mtspr SPRN_DC_CST, r8
871 * Set up to use a given MMU context.
872 * r3 is context number, r4 is PGD pointer.
874 * We place the physical address of the new task page directory loaded
875 * into the MMU base register, and set the ASID compare register with
880 #ifdef CONFIG_BDI_SWITCH
881 /* Context switch the PTE pointer for the Abatron BDI2000.
882 * The PGDIR is passed as second argument.
889 #ifdef CONFIG_8xx_CPU6
890 lis r6, cpu6_errata_word@h
891 ori r6, r6, cpu6_errata_word@l
896 mtspr SPRN_M_TW, r4 /* Update MMU base address */
900 mtspr SPRN_M_CASID, r3 /* Update context */
902 mtspr SPRN_M_CASID,r3 /* Update context */
904 mtspr SPRN_M_TW, r4 /* and pgd */
909 #ifdef CONFIG_8xx_CPU6
910 /* It's here because it is unique to the 8xx.
911 * It is important we get called with interrupts disabled. I used to
912 * do that, but it appears that all code that calls this already had
913 * interrupt disabled.
917 lis r7, cpu6_errata_word@h
918 ori r7, r7, cpu6_errata_word@l
922 mtspr 22, r3 /* Update Decrementer */
928 * We put a few things here that have to be page-aligned.
929 * This stuff goes at the beginning of the data segment,
930 * which is page-aligned.
935 .globl empty_zero_page
940 .globl swapper_pg_dir
942 .space PGD_TABLE_SIZE
944 /* Room for two PTE table poiners, usually the kernel and current user
945 * pointer to their respective root page table (pgdir).
950 #ifdef CONFIG_8xx_CPU6
951 .globl cpu6_errata_word