1/* SPDX-License-Identifier: GPL-2.0-or-later */ 2/* 3 * Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org> 4 * Initial PowerPC version. 5 * Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu> 6 * Rewritten for PReP 7 * Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au> 8 * Low-level exception handers, MMU support, and rewrite. 9 * Copyright (c) 1997 Dan Malek <dmalek@jlc.net> 10 * PowerPC 8xx modifications. 11 * Copyright (c) 1998-1999 TiVo, Inc. 12 * PowerPC 403GCX modifications. 13 * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu> 14 * PowerPC 403GCX/405GP modifications. 15 * Copyright 2000 MontaVista Software Inc. 16 * PPC405 modifications 17 * PowerPC 403GCX/405GP modifications. 18 * Author: MontaVista Software, Inc. 19 * frank_rowand@mvista.com or source@mvista.com 20 * debbie_chu@mvista.com 21 * 22 * Module name: head_4xx.S 23 * 24 * Description: 25 * Kernel execution entry point code. 26 */ 27 28#include <linux/init.h> 29#include <linux/pgtable.h> 30#include <linux/sizes.h> 31#include <linux/linkage.h> 32 33#include <asm/processor.h> 34#include <asm/page.h> 35#include <asm/mmu.h> 36#include <asm/cputable.h> 37#include <asm/thread_info.h> 38#include <asm/ppc_asm.h> 39#include <asm/asm-offsets.h> 40#include <asm/ptrace.h> 41 42#include "head_32.h" 43 44/* As with the other PowerPC ports, it is expected that when code 45 * execution begins here, the following registers contain valid, yet 46 * optional, information: 47 * 48 * r3 - Board info structure pointer (DRAM, frequency, MAC address, etc.) 49 * r4 - Starting address of the init RAM disk 50 * r5 - Ending address of the init RAM disk 51 * r6 - Start of kernel command line string (e.g. "mem=96m") 52 * r7 - End of kernel command line string 53 * 54 * This is all going to change RSN when we add bi_recs....... -- Dan 55 */ 56 __HEAD 57_GLOBAL(_stext); 58_GLOBAL(_start); 59 60 mr r31,r3 /* save device tree ptr */ 61 62 /* We have to turn on the MMU right away so we get cache modes 63 * set correctly. 64 */ 65 bl initial_mmu 66 67/* We now have the lower 16 Meg mapped into TLB entries, and the caches 68 * ready to work. 69 */ 70turn_on_mmu: 71 lis r0,MSR_KERNEL@h 72 ori r0,r0,MSR_KERNEL@l 73 mtspr SPRN_SRR1,r0 74 lis r0,start_here@h 75 ori r0,r0,start_here@l 76 mtspr SPRN_SRR0,r0 77 rfi /* enables MMU */ 78 b . /* prevent prefetch past rfi */ 79 80/* 81 * This area is used for temporarily saving registers during the 82 * critical exception prolog. 83 */ 84 . = 0xc0 85crit_save: 86_GLOBAL(crit_r10) 87 .space 4 88_GLOBAL(crit_r11) 89 .space 4 90_GLOBAL(crit_srr0) 91 .space 4 92_GLOBAL(crit_srr1) 93 .space 4 94_GLOBAL(crit_r1) 95 .space 4 96_GLOBAL(crit_dear) 97 .space 4 98_GLOBAL(crit_esr) 99 .space 4 100 101/* 102 * Exception prolog for critical exceptions. This is a little different 103 * from the normal exception prolog above since a critical exception 104 * can potentially occur at any point during normal exception processing. 105 * Thus we cannot use the same SPRG registers as the normal prolog above. 106 * Instead we use a couple of words of memory at low physical addresses. 107 * This is OK since we don't support SMP on these processors. 108 */ 109.macro CRITICAL_EXCEPTION_PROLOG trapno name 110 stw r10,crit_r10@l(0) /* save two registers to work with */ 111 stw r11,crit_r11@l(0) 112 mfspr r10,SPRN_SRR0 113 mfspr r11,SPRN_SRR1 114 stw r10,crit_srr0@l(0) 115 stw r11,crit_srr1@l(0) 116 mfspr r10,SPRN_DEAR 117 mfspr r11,SPRN_ESR 118 stw r10,crit_dear@l(0) 119 stw r11,crit_esr@l(0) 120 mfcr r10 /* save CR in r10 for now */ 121 mfspr r11,SPRN_SRR3 /* check whether user or kernel */ 122 andi. r11,r11,MSR_PR 123 lis r11,(critirq_ctx-PAGE_OFFSET)@ha 124 lwz r11,(critirq_ctx-PAGE_OFFSET)@l(r11) 125 beq 1f 126 /* COMING FROM USER MODE */ 127 mfspr r11,SPRN_SPRG_THREAD /* if from user, start at top of */ 128 lwz r11,TASK_STACK-THREAD(r11) /* this thread's kernel stack */ 1291: stw r1,crit_r1@l(0) 130 addi r1,r11,THREAD_SIZE-INT_FRAME_SIZE /* Alloc an excpt frm */ 131 LOAD_REG_IMMEDIATE(r11, MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)) /* re-enable MMU */ 132 mtspr SPRN_SRR1, r11 133 lis r11, 1f@h 134 ori r11, r11, 1f@l 135 mtspr SPRN_SRR0, r11 136 rfi 137 138 .text 1391: 140\name\()_virt: 141 lwz r11,crit_r1@l(0) 142 stw r11,GPR1(r1) 143 stw r11,0(r1) 144 mr r11,r1 145 stw r10,_CCR(r11) /* save various registers */ 146 stw r12,GPR12(r11) 147 stw r9,GPR9(r11) 148 mflr r10 149 stw r10,_LINK(r11) 150 lis r9,PAGE_OFFSET@ha 151 lwz r10,crit_r10@l(r9) 152 lwz r12,crit_r11@l(r9) 153 stw r10,GPR10(r11) 154 stw r12,GPR11(r11) 155 lwz r12,crit_dear@l(r9) 156 lwz r9,crit_esr@l(r9) 157 stw r12,_DEAR(r11) /* since they may have had stuff */ 158 stw r9,_ESR(r11) /* exception was taken */ 159 mfspr r12,SPRN_SRR2 160 mfspr r9,SPRN_SRR3 161 rlwinm r9,r9,0,14,12 /* clear MSR_WE (necessary?) */ 162 COMMON_EXCEPTION_PROLOG_END \trapno + 2 163_ASM_NOKPROBE_SYMBOL(\name\()_virt) 164.endm 165 166 /* 167 * State at this point: 168 * r9 saved in stack frame, now saved SRR3 & ~MSR_WE 169 * r10 saved in crit_r10 and in stack frame, trashed 170 * r11 saved in crit_r11 and in stack frame, 171 * now phys stack/exception frame pointer 172 * r12 saved in stack frame, now saved SRR2 173 * CR saved in stack frame, CR0.EQ = !SRR3.PR 174 * LR, DEAR, ESR in stack frame 175 * r1 saved in stack frame, now virt stack/excframe pointer 176 * r0, r3-r8 saved in stack frame 177 */ 178 179/* 180 * Exception vectors. 181 */ 182#define CRITICAL_EXCEPTION(n, label, hdlr) \ 183 START_EXCEPTION(n, label); \ 184 CRITICAL_EXCEPTION_PROLOG n label; \ 185 prepare_transfer_to_handler; \ 186 bl hdlr; \ 187 b ret_from_crit_exc 188 189/* 190 * 0x0100 - Critical Interrupt Exception 191 */ 192 CRITICAL_EXCEPTION(0x0100, CriticalInterrupt, unknown_exception) 193 194/* 195 * 0x0200 - Machine Check Exception 196 */ 197 CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception) 198 199/* 200 * 0x0300 - Data Storage Exception 201 * This happens for just a few reasons. U0 set (but we don't do that), 202 * or zone protection fault (user violation, write to protected page). 203 * The other Data TLB exceptions bail out to this point 204 * if they can't resolve the lightweight TLB fault. 205 */ 206 START_EXCEPTION(0x0300, DataStorage) 207 EXCEPTION_PROLOG 0x300 DataStorage handle_dar_dsisr=1 208 prepare_transfer_to_handler 209 bl do_page_fault 210 b interrupt_return 211 212/* 213 * 0x0400 - Instruction Storage Exception 214 * This is caused by a fetch from non-execute or guarded pages. 215 */ 216 START_EXCEPTION(0x0400, InstructionAccess) 217 EXCEPTION_PROLOG 0x400 InstructionAccess 218 li r5,0 219 stw r5, _ESR(r11) /* Zero ESR */ 220 stw r12, _DEAR(r11) /* SRR0 as DEAR */ 221 prepare_transfer_to_handler 222 bl do_page_fault 223 b interrupt_return 224 225/* 0x0500 - External Interrupt Exception */ 226 EXCEPTION(0x0500, HardwareInterrupt, do_IRQ) 227 228/* 0x0600 - Alignment Exception */ 229 START_EXCEPTION(0x0600, Alignment) 230 EXCEPTION_PROLOG 0x600 Alignment handle_dar_dsisr=1 231 prepare_transfer_to_handler 232 bl alignment_exception 233 REST_NVGPRS(r1) 234 b interrupt_return 235 236/* 0x0700 - Program Exception */ 237 START_EXCEPTION(0x0700, ProgramCheck) 238 EXCEPTION_PROLOG 0x700 ProgramCheck handle_dar_dsisr=1 239 prepare_transfer_to_handler 240 bl program_check_exception 241 REST_NVGPRS(r1) 242 b interrupt_return 243 244 EXCEPTION(0x0800, Trap_08, unknown_exception) 245 EXCEPTION(0x0900, Trap_09, unknown_exception) 246 EXCEPTION(0x0A00, Trap_0A, unknown_exception) 247 EXCEPTION(0x0B00, Trap_0B, unknown_exception) 248 249/* 0x0C00 - System Call Exception */ 250 START_EXCEPTION(0x0C00, SystemCall) 251 SYSCALL_ENTRY 0xc00 252/* Trap_0D is commented out to get more space for system call exception */ 253 254/* EXCEPTION(0x0D00, Trap_0D, unknown_exception) */ 255 EXCEPTION(0x0E00, Trap_0E, unknown_exception) 256 EXCEPTION(0x0F00, Trap_0F, unknown_exception) 257 258/* 0x1000 - Programmable Interval Timer (PIT) Exception */ 259 START_EXCEPTION(0x1000, DecrementerTrap) 260 b Decrementer 261 262/* 0x1010 - Fixed Interval Timer (FIT) Exception */ 263 START_EXCEPTION(0x1010, FITExceptionTrap) 264 b FITException 265 266/* 0x1020 - Watchdog Timer (WDT) Exception */ 267 START_EXCEPTION(0x1020, WDTExceptionTrap) 268 b WDTException 269 270/* 0x1100 - Data TLB Miss Exception 271 * As the name implies, translation is not in the MMU, so search the 272 * page tables and fix it. The only purpose of this function is to 273 * load TLB entries from the page table if they exist. 274 */ 275 START_EXCEPTION(0x1100, DTLBMiss) 276 mtspr SPRN_SPRG_SCRATCH5, r10 /* Save some working registers */ 277 mtspr SPRN_SPRG_SCRATCH6, r11 278 mtspr SPRN_SPRG_SCRATCH3, r12 279 mtspr SPRN_SPRG_SCRATCH4, r9 280 mfcr r12 281 mfspr r9, SPRN_PID 282 rlwimi r12, r9, 0, 0xff 283 mfspr r10, SPRN_DEAR /* Get faulting address */ 284 285 /* If we are faulting a kernel address, we have to use the 286 * kernel page tables. 287 */ 288 lis r11, PAGE_OFFSET@h 289 cmplw r10, r11 290 blt+ 3f 291 lis r11, swapper_pg_dir@h 292 ori r11, r11, swapper_pg_dir@l 293 li r9, 0 294 mtspr SPRN_PID, r9 /* TLB will have 0 TID */ 295 b 4f 296 297 /* Get the PGD for the current thread. 298 */ 2993: 300 mfspr r11,SPRN_SPRG_THREAD 301 lwz r11,PGDIR(r11) 302#ifdef CONFIG_PPC_KUAP 303 rlwinm. r9, r9, 0, 0xff 304 beq 5f /* Kuap fault */ 305#endif 3064: 307 tophys(r11, r11) 308 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ 309 lwz r11, 0(r11) /* Get L1 entry */ 310 andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */ 311 beq 2f /* Bail if no table */ 312 313 rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */ 314 lwz r11, 0(r11) /* Get Linux PTE */ 315 li r9, _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_READ 316 andc. r9, r9, r11 /* Check permission */ 317 bne 5f 318 319 rlwinm r9, r11, 1, _PAGE_WRITE /* dirty => w */ 320 and r9, r9, r11 /* hwwrite = dirty & w */ 321 rlwimi r11, r9, 0, _PAGE_WRITE /* replace w by hwwrite */ 322 323 /* Create TLB tag. This is the faulting address plus a static 324 * set of bits. These are size, valid, E, U0. 325 */ 326 li r9, 0x00c0 327 rlwimi r10, r9, 0, 20, 31 328 329 b finish_tlb_load 330 3312: /* Check for possible large-page pmd entry */ 332 rlwinm. r9, r11, 2, 22, 24 333 beq 5f 334 335 /* Create TLB tag. This is the faulting address, plus a static 336 * set of bits (valid, E, U0) plus the size from the PMD. 337 */ 338 ori r9, r9, 0x40 339 rlwimi r10, r9, 0, 20, 31 340 341 b finish_tlb_load 342 3435: 344 /* The bailout. Restore registers to pre-exception conditions 345 * and call the heavyweights to help us out. 346 */ 347 mtspr SPRN_PID, r12 348 mtcrf 0x80, r12 349 mfspr r9, SPRN_SPRG_SCRATCH4 350 mfspr r12, SPRN_SPRG_SCRATCH3 351 mfspr r11, SPRN_SPRG_SCRATCH6 352 mfspr r10, SPRN_SPRG_SCRATCH5 353 b DataStorage 354 355/* 0x1200 - Instruction TLB Miss Exception 356 * Nearly the same as above, except we get our information from different 357 * registers and bailout to a different point. 358 */ 359 START_EXCEPTION(0x1200, ITLBMiss) 360 mtspr SPRN_SPRG_SCRATCH5, r10 /* Save some working registers */ 361 mtspr SPRN_SPRG_SCRATCH6, r11 362 mtspr SPRN_SPRG_SCRATCH3, r12 363 mtspr SPRN_SPRG_SCRATCH4, r9 364 mfcr r12 365 mfspr r9, SPRN_PID 366 rlwimi r12, r9, 0, 0xff 367 mfspr r10, SPRN_SRR0 /* Get faulting address */ 368 369 /* If we are faulting a kernel address, we have to use the 370 * kernel page tables. 371 */ 372 lis r11, PAGE_OFFSET@h 373 cmplw r10, r11 374 blt+ 3f 375 lis r11, swapper_pg_dir@h 376 ori r11, r11, swapper_pg_dir@l 377 li r9, 0 378 mtspr SPRN_PID, r9 /* TLB will have 0 TID */ 379 b 4f 380 381 /* Get the PGD for the current thread. 382 */ 3833: 384 mfspr r11,SPRN_SPRG_THREAD 385 lwz r11,PGDIR(r11) 386#ifdef CONFIG_PPC_KUAP 387 rlwinm. r9, r9, 0, 0xff 388 beq 5f /* Kuap fault */ 389#endif 3904: 391 tophys(r11, r11) 392 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ 393 lwz r11, 0(r11) /* Get L1 entry */ 394 andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */ 395 beq 2f /* Bail if no table */ 396 397 rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */ 398 lwz r11, 0(r11) /* Get Linux PTE */ 399 li r9, _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC 400 andc. r9, r9, r11 /* Check permission */ 401 bne 5f 402 403 rlwinm r9, r11, 1, _PAGE_WRITE /* dirty => w */ 404 and r9, r9, r11 /* hwwrite = dirty & w */ 405 rlwimi r11, r9, 0, _PAGE_WRITE /* replace w by hwwrite */ 406 407 /* Create TLB tag. This is the faulting address plus a static 408 * set of bits. These are size, valid, E, U0. 409 */ 410 li r9, 0x00c0 411 rlwimi r10, r9, 0, 20, 31 412 413 b finish_tlb_load 414 4152: /* Check for possible large-page pmd entry */ 416 rlwinm. r9, r11, 2, 22, 24 417 beq 5f 418 419 /* Create TLB tag. This is the faulting address, plus a static 420 * set of bits (valid, E, U0) plus the size from the PMD. 421 */ 422 ori r9, r9, 0x40 423 rlwimi r10, r9, 0, 20, 31 424 425 b finish_tlb_load 426 4275: 428 /* The bailout. Restore registers to pre-exception conditions 429 * and call the heavyweights to help us out. 430 */ 431 mtspr SPRN_PID, r12 432 mtcrf 0x80, r12 433 mfspr r9, SPRN_SPRG_SCRATCH4 434 mfspr r12, SPRN_SPRG_SCRATCH3 435 mfspr r11, SPRN_SPRG_SCRATCH6 436 mfspr r10, SPRN_SPRG_SCRATCH5 437 b InstructionAccess 438 439 EXCEPTION(0x1300, Trap_13, unknown_exception) 440 EXCEPTION(0x1400, Trap_14, unknown_exception) 441 EXCEPTION(0x1500, Trap_15, unknown_exception) 442 EXCEPTION(0x1600, Trap_16, unknown_exception) 443 EXCEPTION(0x1700, Trap_17, unknown_exception) 444 EXCEPTION(0x1800, Trap_18, unknown_exception) 445 EXCEPTION(0x1900, Trap_19, unknown_exception) 446 EXCEPTION(0x1A00, Trap_1A, unknown_exception) 447 EXCEPTION(0x1B00, Trap_1B, unknown_exception) 448 EXCEPTION(0x1C00, Trap_1C, unknown_exception) 449 EXCEPTION(0x1D00, Trap_1D, unknown_exception) 450 EXCEPTION(0x1E00, Trap_1E, unknown_exception) 451 EXCEPTION(0x1F00, Trap_1F, unknown_exception) 452 453/* Check for a single step debug exception while in an exception 454 * handler before state has been saved. This is to catch the case 455 * where an instruction that we are trying to single step causes 456 * an exception (eg ITLB/DTLB miss) and thus the first instruction of 457 * the exception handler generates a single step debug exception. 458 * 459 * If we get a debug trap on the first instruction of an exception handler, 460 * we reset the MSR_DE in the _exception handler's_ MSR (the debug trap is 461 * a critical exception, so we are using SPRN_CSRR1 to manipulate the MSR). 462 * The exception handler was handling a non-critical interrupt, so it will 463 * save (and later restore) the MSR via SPRN_SRR1, which will still have 464 * the MSR_DE bit set. 465 */ 466 /* 0x2000 - Debug Exception */ 467 START_EXCEPTION(0x2000, DebugTrap) 468 CRITICAL_EXCEPTION_PROLOG 0x2000 DebugTrap 469 470 /* 471 * If this is a single step or branch-taken exception in an 472 * exception entry sequence, it was probably meant to apply to 473 * the code where the exception occurred (since exception entry 474 * doesn't turn off DE automatically). We simulate the effect 475 * of turning off DE on entry to an exception handler by turning 476 * off DE in the SRR3 value and clearing the debug status. 477 */ 478 mfspr r10,SPRN_DBSR /* check single-step/branch taken */ 479 andis. r10,r10,DBSR_IC@h 480 beq+ 2f 481 482 andi. r10,r9,MSR_IR|MSR_PR /* check supervisor + MMU off */ 483 beq 1f /* branch and fix it up */ 484 485 mfspr r10,SPRN_SRR2 /* Faulting instruction address */ 486 cmplwi r10,0x2100 487 bgt+ 2f /* address above exception vectors */ 488 489 /* here it looks like we got an inappropriate debug exception. */ 4901: rlwinm r9,r9,0,~MSR_DE /* clear DE in the SRR3 value */ 491 lis r10,DBSR_IC@h /* clear the IC event */ 492 mtspr SPRN_DBSR,r10 493 /* restore state and get out */ 494 lwz r10,_CCR(r11) 495 lwz r0,GPR0(r11) 496 lwz r1,GPR1(r11) 497 mtcrf 0x80,r10 498 mtspr SPRN_SRR2,r12 499 mtspr SPRN_SRR3,r9 500 lwz r9,GPR9(r11) 501 lwz r12,GPR12(r11) 502 lwz r10,crit_r10@l(0) 503 lwz r11,crit_r11@l(0) 504 rfci 505 b . 506 507 /* continue normal handling for a critical exception... */ 5082: mfspr r4,SPRN_DBSR 509 stw r4,_ESR(r11) /* DebugException takes DBSR in _ESR */ 510 prepare_transfer_to_handler 511 bl DebugException 512 b ret_from_crit_exc 513 514 /* Programmable Interval Timer (PIT) Exception. (from 0x1000) */ 515 __HEAD 516Decrementer: 517 EXCEPTION_PROLOG 0x1000 Decrementer 518 lis r0,TSR_PIS@h 519 mtspr SPRN_TSR,r0 /* Clear the PIT exception */ 520 prepare_transfer_to_handler 521 bl timer_interrupt 522 b interrupt_return 523 524 /* Fixed Interval Timer (FIT) Exception. (from 0x1010) */ 525 __HEAD 526FITException: 527 EXCEPTION_PROLOG 0x1010 FITException 528 prepare_transfer_to_handler 529 bl unknown_exception 530 b interrupt_return 531 532 /* Watchdog Timer (WDT) Exception. (from 0x1020) */ 533 __HEAD 534WDTException: 535 CRITICAL_EXCEPTION_PROLOG 0x1020 WDTException 536 prepare_transfer_to_handler 537 bl WatchdogException 538 b ret_from_crit_exc 539 540/* Other PowerPC processors, namely those derived from the 6xx-series 541 * have vectors from 0x2100 through 0x2F00 defined, but marked as reserved. 542 * However, for the 4xx-series processors these are neither defined nor 543 * reserved. 544 */ 545 546 __HEAD 547 /* Damn, I came up one instruction too many to fit into the 548 * exception space :-). Both the instruction and data TLB 549 * miss get to this point to load the TLB. 550 * r10 - TLB_TAG value 551 * r11 - Linux PTE 552 * r9 - available to use 553 * PID - loaded with proper value when we get here 554 * Upon exit, we reload everything and RFI. 555 * Actually, it will fit now, but oh well.....a common place 556 * to load the TLB. 557 */ 558tlb_4xx_index: 559 .long 0 560finish_tlb_load: 561 /* 562 * Clear out the software-only bits in the PTE to generate the 563 * TLB_DATA value. These are the bottom 2 bits of the RPM, the 564 * 4 bits of the zone field, and M. 565 */ 566 li r9, 0x0cf2 567 andc r11, r11, r9 568 rlwimi r11, r10, 8, 24, 27 /* Copy 4 upper address bit into zone */ 569 570 /* load the next available TLB index. */ 571 lwz r9, tlb_4xx_index@l(0) 572 addi r9, r9, 1 573 andi. r9, r9, PPC40X_TLB_SIZE - 1 574 stw r9, tlb_4xx_index@l(0) 575 576 tlbwe r11, r9, TLB_DATA /* Load TLB LO */ 577 tlbwe r10, r9, TLB_TAG /* Load TLB HI */ 578 579 /* Done...restore registers and get out of here. 580 */ 581 mtspr SPRN_PID, r12 582 mtcrf 0x80, r12 583 mfspr r9, SPRN_SPRG_SCRATCH4 584 mfspr r12, SPRN_SPRG_SCRATCH3 585 mfspr r11, SPRN_SPRG_SCRATCH6 586 mfspr r10, SPRN_SPRG_SCRATCH5 587 rfi /* Should sync shadow TLBs */ 588 b . /* prevent prefetch past rfi */ 589 590/* This is where the main kernel code starts. 591 */ 592start_here: 593 594 /* ptr to current */ 595 lis r2,init_task@h 596 ori r2,r2,init_task@l 597 598 /* ptr to phys current thread */ 599 tophys(r4,r2) 600 addi r4,r4,THREAD /* init task's THREAD */ 601 mtspr SPRN_SPRG_THREAD,r4 602 603 /* stack */ 604 lis r1,init_thread_union@ha 605 addi r1,r1,init_thread_union@l 606 li r0,0 607 stwu r0,THREAD_SIZE-STACK_FRAME_MIN_SIZE(r1) 608 609 bl early_init /* We have to do this with MMU on */ 610 611/* 612 * Decide what sort of machine this is and initialize the MMU. 613 */ 614#ifdef CONFIG_KASAN 615 bl kasan_early_init 616#endif 617 li r3,0 618 mr r4,r31 619 bl machine_init 620 bl MMU_init 621 622/* Go back to running unmapped so we can load up new values 623 * and change to using our exception vectors. 624 * On the 4xx, all we have to do is invalidate the TLB to clear 625 * the old 16M byte TLB mappings. 626 */ 627 lis r4,2f@h 628 ori r4,r4,2f@l 629 tophys(r4,r4) 630 lis r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@h 631 ori r3,r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@l 632 mtspr SPRN_SRR0,r4 633 mtspr SPRN_SRR1,r3 634 rfi 635 b . /* prevent prefetch past rfi */ 636 637/* Load up the kernel context */ 6382: 639 sync /* Flush to memory before changing TLB */ 640 tlbia 641 isync /* Flush shadow TLBs */ 642 643 /* set up the PTE pointers for the Abatron bdiGDB. 644 */ 645 lis r6, swapper_pg_dir@h 646 ori r6, r6, swapper_pg_dir@l 647 lis r5, abatron_pteptrs@h 648 ori r5, r5, abatron_pteptrs@l 649 stw r5, 0xf0(0) /* Must match your Abatron config file */ 650 tophys(r5,r5) 651 stw r6, 0(r5) 652 653/* Now turn on the MMU for real! */ 654 lis r4,MSR_KERNEL@h 655 ori r4,r4,MSR_KERNEL@l 656 lis r3,start_kernel@h 657 ori r3,r3,start_kernel@l 658 mtspr SPRN_SRR0,r3 659 mtspr SPRN_SRR1,r4 660 rfi /* enable MMU and jump to start_kernel */ 661 b . /* prevent prefetch past rfi */ 662 663/* Set up the initial MMU state so we can do the first level of 664 * kernel initialization. This maps the first 32 MBytes of memory 1:1 665 * virtual to physical and more importantly sets the cache mode. 666 */ 667SYM_FUNC_START_LOCAL(initial_mmu) 668 tlbia /* Invalidate all TLB entries */ 669 isync 670 671 /* We should still be executing code at physical address 0x0000xxxx 672 * at this point. However, start_here is at virtual address 673 * 0xC000xxxx. So, set up a TLB mapping to cover this once 674 * translation is enabled. 675 */ 676 677 lis r3,KERNELBASE@h /* Load the kernel virtual address */ 678 ori r3,r3,KERNELBASE@l 679 tophys(r4,r3) /* Load the kernel physical address */ 680 681 iccci r0,r3 /* Invalidate the i-cache before use */ 682 683 /* Load the kernel PID. 684 */ 685 li r0,0 686 mtspr SPRN_PID,r0 687 sync 688 689 /* Configure and load one entry into TLB slots 63 */ 690 clrrwi r4,r4,10 /* Mask off the real page number */ 691 ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */ 692 693 clrrwi r3,r3,10 /* Mask off the effective page number */ 694 ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M)) 695 696 li r0,63 /* TLB slot 63 */ 697 698 tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */ 699 tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */ 700 701 li r0,62 /* TLB slot 62 */ 702 addis r4,r4,SZ_16M@h 703 addis r3,r3,SZ_16M@h 704 tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */ 705 tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */ 706 707 isync 708 709 /* Establish the exception vector base 710 */ 711 lis r4,KERNELBASE@h /* EVPR only uses the high 16-bits */ 712 tophys(r0,r4) /* Use the physical address */ 713 mtspr SPRN_EVPR,r0 714 715 blr 716SYM_FUNC_END(initial_mmu) 717 718_GLOBAL(abort) 719 mfspr r13,SPRN_DBCR0 720 oris r13,r13,DBCR0_RST_SYSTEM@h 721 mtspr SPRN_DBCR0,r13 722