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 <asm/processor.h> 32#include <asm/page.h> 33#include <asm/mmu.h> 34#include <asm/cputable.h> 35#include <asm/thread_info.h> 36#include <asm/ppc_asm.h> 37#include <asm/asm-offsets.h> 38#include <asm/ptrace.h> 39#include <asm/export.h> 40 41#include "head_32.h" 42 43/* As with the other PowerPC ports, it is expected that when code 44 * execution begins here, the following registers contain valid, yet 45 * optional, information: 46 * 47 * r3 - Board info structure pointer (DRAM, frequency, MAC address, etc.) 48 * r4 - Starting address of the init RAM disk 49 * r5 - Ending address of the init RAM disk 50 * r6 - Start of kernel command line string (e.g. "mem=96m") 51 * r7 - End of kernel command line string 52 * 53 * This is all going to change RSN when we add bi_recs....... -- Dan 54 */ 55 __HEAD 56_ENTRY(_stext); 57_ENTRY(_start); 58 59 mr r31,r3 /* save device tree ptr */ 60 61 /* We have to turn on the MMU right away so we get cache modes 62 * set correctly. 63 */ 64 bl initial_mmu 65 66/* We now have the lower 16 Meg mapped into TLB entries, and the caches 67 * ready to work. 68 */ 69turn_on_mmu: 70 lis r0,MSR_KERNEL@h 71 ori r0,r0,MSR_KERNEL@l 72 mtspr SPRN_SRR1,r0 73 lis r0,start_here@h 74 ori r0,r0,start_here@l 75 mtspr SPRN_SRR0,r0 76 rfi /* enables MMU */ 77 b . /* prevent prefetch past rfi */ 78 79/* 80 * This area is used for temporarily saving registers during the 81 * critical exception prolog. 82 */ 83 . = 0xc0 84crit_save: 85_ENTRY(crit_r10) 86 .space 4 87_ENTRY(crit_r11) 88 .space 4 89_ENTRY(crit_srr0) 90 .space 4 91_ENTRY(crit_srr1) 92 .space 4 93_ENTRY(saved_ksp_limit) 94 .space 4 95 96/* 97 * Exception prolog for critical exceptions. This is a little different 98 * from the normal exception prolog above since a critical exception 99 * can potentially occur at any point during normal exception processing. 100 * Thus we cannot use the same SPRG registers as the normal prolog above. 101 * Instead we use a couple of words of memory at low physical addresses. 102 * This is OK since we don't support SMP on these processors. 103 */ 104#define CRITICAL_EXCEPTION_PROLOG \ 105 stw r10,crit_r10@l(0); /* save two registers to work with */\ 106 stw r11,crit_r11@l(0); \ 107 mfcr r10; /* save CR in r10 for now */\ 108 mfspr r11,SPRN_SRR3; /* check whether user or kernel */\ 109 andi. r11,r11,MSR_PR; \ 110 lis r11,critirq_ctx@ha; \ 111 tophys(r11,r11); \ 112 lwz r11,critirq_ctx@l(r11); \ 113 beq 1f; \ 114 /* COMING FROM USER MODE */ \ 115 mfspr r11,SPRN_SPRG_THREAD; /* if from user, start at top of */\ 116 lwz r11,TASK_STACK-THREAD(r11); /* this thread's kernel stack */\ 1171: addi r11,r11,THREAD_SIZE-INT_FRAME_SIZE; /* Alloc an excpt frm */\ 118 tophys(r11,r11); \ 119 stw r10,_CCR(r11); /* save various registers */\ 120 stw r12,GPR12(r11); \ 121 stw r9,GPR9(r11); \ 122 mflr r10; \ 123 stw r10,_LINK(r11); \ 124 mfspr r12,SPRN_DEAR; /* save DEAR and ESR in the frame */\ 125 stw r12,_DEAR(r11); /* since they may have had stuff */\ 126 mfspr r9,SPRN_ESR; /* in them at the point where the */\ 127 stw r9,_ESR(r11); /* exception was taken */\ 128 mfspr r12,SPRN_SRR2; \ 129 stw r1,GPR1(r11); \ 130 mfspr r9,SPRN_SRR3; \ 131 stw r1,0(r11); \ 132 tovirt(r1,r11); \ 133 rlwinm r9,r9,0,14,12; /* clear MSR_WE (necessary?) */\ 134 stw r0,GPR0(r11); \ 135 lis r10, STACK_FRAME_REGS_MARKER@ha; /* exception frame marker */\ 136 addi r10, r10, STACK_FRAME_REGS_MARKER@l; \ 137 stw r10, 8(r11); \ 138 SAVE_4GPRS(3, r11); \ 139 SAVE_2GPRS(7, r11) 140 141 /* 142 * State at this point: 143 * r9 saved in stack frame, now saved SRR3 & ~MSR_WE 144 * r10 saved in crit_r10 and in stack frame, trashed 145 * r11 saved in crit_r11 and in stack frame, 146 * now phys stack/exception frame pointer 147 * r12 saved in stack frame, now saved SRR2 148 * CR saved in stack frame, CR0.EQ = !SRR3.PR 149 * LR, DEAR, ESR in stack frame 150 * r1 saved in stack frame, now virt stack/excframe pointer 151 * r0, r3-r8 saved in stack frame 152 */ 153 154/* 155 * Exception vectors. 156 */ 157#define CRITICAL_EXCEPTION(n, label, hdlr) \ 158 START_EXCEPTION(n, label); \ 159 CRITICAL_EXCEPTION_PROLOG; \ 160 addi r3,r1,STACK_FRAME_OVERHEAD; \ 161 EXC_XFER_TEMPLATE(hdlr, n+2, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \ 162 crit_transfer_to_handler, ret_from_crit_exc) 163 164/* 165 * 0x0100 - Critical Interrupt Exception 166 */ 167 CRITICAL_EXCEPTION(0x0100, CriticalInterrupt, unknown_exception) 168 169/* 170 * 0x0200 - Machine Check Exception 171 */ 172 CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception) 173 174/* 175 * 0x0300 - Data Storage Exception 176 * This happens for just a few reasons. U0 set (but we don't do that), 177 * or zone protection fault (user violation, write to protected page). 178 * The other Data TLB exceptions bail out to this point 179 * if they can't resolve the lightweight TLB fault. 180 */ 181 START_EXCEPTION(0x0300, DataStorage) 182 EXCEPTION_PROLOG 183 mfspr r5, SPRN_ESR /* Grab the ESR, save it, pass arg3 */ 184 stw r5, _ESR(r11) 185 mfspr r4, SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */ 186 stw r4, _DEAR(r11) 187 EXC_XFER_LITE(0x300, handle_page_fault) 188 189/* 190 * 0x0400 - Instruction Storage Exception 191 * This is caused by a fetch from non-execute or guarded pages. 192 */ 193 START_EXCEPTION(0x0400, InstructionAccess) 194 EXCEPTION_PROLOG 195 mr r4,r12 /* Pass SRR0 as arg2 */ 196 stw r4, _DEAR(r11) 197 li r5,0 /* Pass zero as arg3 */ 198 EXC_XFER_LITE(0x400, handle_page_fault) 199 200/* 0x0500 - External Interrupt Exception */ 201 EXCEPTION(0x0500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE) 202 203/* 0x0600 - Alignment Exception */ 204 START_EXCEPTION(0x0600, Alignment) 205 EXCEPTION_PROLOG 206 mfspr r4,SPRN_DEAR /* Grab the DEAR and save it */ 207 stw r4,_DEAR(r11) 208 addi r3,r1,STACK_FRAME_OVERHEAD 209 EXC_XFER_STD(0x600, alignment_exception) 210 211/* 0x0700 - Program Exception */ 212 START_EXCEPTION(0x0700, ProgramCheck) 213 EXCEPTION_PROLOG 214 mfspr r4,SPRN_ESR /* Grab the ESR and save it */ 215 stw r4,_ESR(r11) 216 addi r3,r1,STACK_FRAME_OVERHEAD 217 EXC_XFER_STD(0x700, program_check_exception) 218 219 EXCEPTION(0x0800, Trap_08, unknown_exception, EXC_XFER_STD) 220 EXCEPTION(0x0900, Trap_09, unknown_exception, EXC_XFER_STD) 221 EXCEPTION(0x0A00, Trap_0A, unknown_exception, EXC_XFER_STD) 222 EXCEPTION(0x0B00, Trap_0B, unknown_exception, EXC_XFER_STD) 223 224/* 0x0C00 - System Call Exception */ 225 START_EXCEPTION(0x0C00, SystemCall) 226 SYSCALL_ENTRY 0xc00 227/* Trap_0D is commented out to get more space for system call exception */ 228 229/* EXCEPTION(0x0D00, Trap_0D, unknown_exception, EXC_XFER_STD) */ 230 EXCEPTION(0x0E00, Trap_0E, unknown_exception, EXC_XFER_STD) 231 EXCEPTION(0x0F00, Trap_0F, unknown_exception, EXC_XFER_STD) 232 233/* 0x1000 - Programmable Interval Timer (PIT) Exception */ 234 . = 0x1000 235 b Decrementer 236 237/* 0x1010 - Fixed Interval Timer (FIT) Exception 238*/ 239 . = 0x1010 240 b FITException 241 242/* 0x1020 - Watchdog Timer (WDT) Exception 243*/ 244 . = 0x1020 245 b WDTException 246 247/* 0x1100 - Data TLB Miss Exception 248 * As the name implies, translation is not in the MMU, so search the 249 * page tables and fix it. The only purpose of this function is to 250 * load TLB entries from the page table if they exist. 251 */ 252 START_EXCEPTION(0x1100, DTLBMiss) 253 mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */ 254 mtspr SPRN_SPRG_SCRATCH1, r11 255 mtspr SPRN_SPRG_SCRATCH3, r12 256 mtspr SPRN_SPRG_SCRATCH4, r9 257 mfcr r12 258 mfspr r9, SPRN_PID 259 mtspr SPRN_SPRG_SCRATCH5, r9 260 mfspr r10, SPRN_DEAR /* Get faulting address */ 261 262 /* If we are faulting a kernel address, we have to use the 263 * kernel page tables. 264 */ 265 lis r11, PAGE_OFFSET@h 266 cmplw r10, r11 267 blt+ 3f 268 lis r11, swapper_pg_dir@h 269 ori r11, r11, swapper_pg_dir@l 270 li r9, 0 271 mtspr SPRN_PID, r9 /* TLB will have 0 TID */ 272 b 4f 273 274 /* Get the PGD for the current thread. 275 */ 2763: 277 mfspr r11,SPRN_SPRG_THREAD 278 lwz r11,PGDIR(r11) 2794: 280 tophys(r11, r11) 281 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ 282 lwz r11, 0(r11) /* Get L1 entry */ 283 andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */ 284 beq 2f /* Bail if no table */ 285 286 rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */ 287 lwz r11, 0(r11) /* Get Linux PTE */ 288 li r9, _PAGE_PRESENT | _PAGE_ACCESSED 289 andc. r9, r9, r11 /* Check permission */ 290 bne 5f 291 292 rlwinm r9, r11, 1, _PAGE_RW /* dirty => rw */ 293 and r9, r9, r11 /* hwwrite = dirty & rw */ 294 rlwimi r11, r9, 0, _PAGE_RW /* replace rw by hwwrite */ 295 296 /* Create TLB tag. This is the faulting address plus a static 297 * set of bits. These are size, valid, E, U0. 298 */ 299 li r9, 0x00c0 300 rlwimi r10, r9, 0, 20, 31 301 302 b finish_tlb_load 303 3042: /* Check for possible large-page pmd entry */ 305 rlwinm. r9, r11, 2, 22, 24 306 beq 5f 307 308 /* Create TLB tag. This is the faulting address, plus a static 309 * set of bits (valid, E, U0) plus the size from the PMD. 310 */ 311 ori r9, r9, 0x40 312 rlwimi r10, r9, 0, 20, 31 313 314 b finish_tlb_load 315 3165: 317 /* The bailout. Restore registers to pre-exception conditions 318 * and call the heavyweights to help us out. 319 */ 320 mfspr r9, SPRN_SPRG_SCRATCH5 321 mtspr SPRN_PID, r9 322 mtcr r12 323 mfspr r9, SPRN_SPRG_SCRATCH4 324 mfspr r12, SPRN_SPRG_SCRATCH3 325 mfspr r11, SPRN_SPRG_SCRATCH1 326 mfspr r10, SPRN_SPRG_SCRATCH0 327 b DataStorage 328 329/* 0x1200 - Instruction TLB Miss Exception 330 * Nearly the same as above, except we get our information from different 331 * registers and bailout to a different point. 332 */ 333 START_EXCEPTION(0x1200, ITLBMiss) 334 mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */ 335 mtspr SPRN_SPRG_SCRATCH1, r11 336 mtspr SPRN_SPRG_SCRATCH3, r12 337 mtspr SPRN_SPRG_SCRATCH4, r9 338 mfcr r12 339 mfspr r9, SPRN_PID 340 mtspr SPRN_SPRG_SCRATCH5, r9 341 mfspr r10, SPRN_SRR0 /* Get faulting address */ 342 343 /* If we are faulting a kernel address, we have to use the 344 * kernel page tables. 345 */ 346 lis r11, PAGE_OFFSET@h 347 cmplw r10, r11 348 blt+ 3f 349 lis r11, swapper_pg_dir@h 350 ori r11, r11, swapper_pg_dir@l 351 li r9, 0 352 mtspr SPRN_PID, r9 /* TLB will have 0 TID */ 353 b 4f 354 355 /* Get the PGD for the current thread. 356 */ 3573: 358 mfspr r11,SPRN_SPRG_THREAD 359 lwz r11,PGDIR(r11) 3604: 361 tophys(r11, r11) 362 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ 363 lwz r11, 0(r11) /* Get L1 entry */ 364 andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */ 365 beq 2f /* Bail if no table */ 366 367 rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */ 368 lwz r11, 0(r11) /* Get Linux PTE */ 369 li r9, _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC 370 andc. r9, r9, r11 /* Check permission */ 371 bne 5f 372 373 rlwinm r9, r11, 1, _PAGE_RW /* dirty => rw */ 374 and r9, r9, r11 /* hwwrite = dirty & rw */ 375 rlwimi r11, r9, 0, _PAGE_RW /* replace rw by hwwrite */ 376 377 /* Create TLB tag. This is the faulting address plus a static 378 * set of bits. These are size, valid, E, U0. 379 */ 380 li r9, 0x00c0 381 rlwimi r10, r9, 0, 20, 31 382 383 b finish_tlb_load 384 3852: /* Check for possible large-page pmd entry */ 386 rlwinm. r9, r11, 2, 22, 24 387 beq 5f 388 389 /* Create TLB tag. This is the faulting address, plus a static 390 * set of bits (valid, E, U0) plus the size from the PMD. 391 */ 392 ori r9, r9, 0x40 393 rlwimi r10, r9, 0, 20, 31 394 395 b finish_tlb_load 396 3975: 398 /* The bailout. Restore registers to pre-exception conditions 399 * and call the heavyweights to help us out. 400 */ 401 mfspr r9, SPRN_SPRG_SCRATCH5 402 mtspr SPRN_PID, r9 403 mtcr r12 404 mfspr r9, SPRN_SPRG_SCRATCH4 405 mfspr r12, SPRN_SPRG_SCRATCH3 406 mfspr r11, SPRN_SPRG_SCRATCH1 407 mfspr r10, SPRN_SPRG_SCRATCH0 408 b InstructionAccess 409 410 EXCEPTION(0x1300, Trap_13, unknown_exception, EXC_XFER_STD) 411 EXCEPTION(0x1400, Trap_14, unknown_exception, EXC_XFER_STD) 412 EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_STD) 413 EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_STD) 414 EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_STD) 415 EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_STD) 416 EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_STD) 417 EXCEPTION(0x1A00, Trap_1A, unknown_exception, EXC_XFER_STD) 418 EXCEPTION(0x1B00, Trap_1B, unknown_exception, EXC_XFER_STD) 419 EXCEPTION(0x1C00, Trap_1C, unknown_exception, EXC_XFER_STD) 420 EXCEPTION(0x1D00, Trap_1D, unknown_exception, EXC_XFER_STD) 421 EXCEPTION(0x1E00, Trap_1E, unknown_exception, EXC_XFER_STD) 422 EXCEPTION(0x1F00, Trap_1F, unknown_exception, EXC_XFER_STD) 423 424/* Check for a single step debug exception while in an exception 425 * handler before state has been saved. This is to catch the case 426 * where an instruction that we are trying to single step causes 427 * an exception (eg ITLB/DTLB miss) and thus the first instruction of 428 * the exception handler generates a single step debug exception. 429 * 430 * If we get a debug trap on the first instruction of an exception handler, 431 * we reset the MSR_DE in the _exception handler's_ MSR (the debug trap is 432 * a critical exception, so we are using SPRN_CSRR1 to manipulate the MSR). 433 * The exception handler was handling a non-critical interrupt, so it will 434 * save (and later restore) the MSR via SPRN_SRR1, which will still have 435 * the MSR_DE bit set. 436 */ 437 /* 0x2000 - Debug Exception */ 438 START_EXCEPTION(0x2000, DebugTrap) 439 CRITICAL_EXCEPTION_PROLOG 440 441 /* 442 * If this is a single step or branch-taken exception in an 443 * exception entry sequence, it was probably meant to apply to 444 * the code where the exception occurred (since exception entry 445 * doesn't turn off DE automatically). We simulate the effect 446 * of turning off DE on entry to an exception handler by turning 447 * off DE in the SRR3 value and clearing the debug status. 448 */ 449 mfspr r10,SPRN_DBSR /* check single-step/branch taken */ 450 andis. r10,r10,DBSR_IC@h 451 beq+ 2f 452 453 andi. r10,r9,MSR_IR|MSR_PR /* check supervisor + MMU off */ 454 beq 1f /* branch and fix it up */ 455 456 mfspr r10,SPRN_SRR2 /* Faulting instruction address */ 457 cmplwi r10,0x2100 458 bgt+ 2f /* address above exception vectors */ 459 460 /* here it looks like we got an inappropriate debug exception. */ 4611: rlwinm r9,r9,0,~MSR_DE /* clear DE in the SRR3 value */ 462 lis r10,DBSR_IC@h /* clear the IC event */ 463 mtspr SPRN_DBSR,r10 464 /* restore state and get out */ 465 lwz r10,_CCR(r11) 466 lwz r0,GPR0(r11) 467 lwz r1,GPR1(r11) 468 mtcrf 0x80,r10 469 mtspr SPRN_SRR2,r12 470 mtspr SPRN_SRR3,r9 471 lwz r9,GPR9(r11) 472 lwz r12,GPR12(r11) 473 lwz r10,crit_r10@l(0) 474 lwz r11,crit_r11@l(0) 475 rfci 476 b . 477 478 /* continue normal handling for a critical exception... */ 4792: mfspr r4,SPRN_DBSR 480 addi r3,r1,STACK_FRAME_OVERHEAD 481 EXC_XFER_TEMPLATE(DebugException, 0x2002, \ 482 (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \ 483 crit_transfer_to_handler, ret_from_crit_exc) 484 485 /* Programmable Interval Timer (PIT) Exception. (from 0x1000) */ 486Decrementer: 487 EXCEPTION_PROLOG 488 lis r0,TSR_PIS@h 489 mtspr SPRN_TSR,r0 /* Clear the PIT exception */ 490 addi r3,r1,STACK_FRAME_OVERHEAD 491 EXC_XFER_LITE(0x1000, timer_interrupt) 492 493 /* Fixed Interval Timer (FIT) Exception. (from 0x1010) */ 494FITException: 495 EXCEPTION_PROLOG 496 addi r3,r1,STACK_FRAME_OVERHEAD; 497 EXC_XFER_STD(0x1010, unknown_exception) 498 499 /* Watchdog Timer (WDT) Exception. (from 0x1020) */ 500WDTException: 501 CRITICAL_EXCEPTION_PROLOG; 502 addi r3,r1,STACK_FRAME_OVERHEAD; 503 EXC_XFER_TEMPLATE(WatchdogException, 0x1020+2, 504 (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), 505 crit_transfer_to_handler, ret_from_crit_exc) 506 507/* Other PowerPC processors, namely those derived from the 6xx-series 508 * have vectors from 0x2100 through 0x2F00 defined, but marked as reserved. 509 * However, for the 4xx-series processors these are neither defined nor 510 * reserved. 511 */ 512 513 /* Damn, I came up one instruction too many to fit into the 514 * exception space :-). Both the instruction and data TLB 515 * miss get to this point to load the TLB. 516 * r10 - TLB_TAG value 517 * r11 - Linux PTE 518 * r9 - available to use 519 * PID - loaded with proper value when we get here 520 * Upon exit, we reload everything and RFI. 521 * Actually, it will fit now, but oh well.....a common place 522 * to load the TLB. 523 */ 524tlb_4xx_index: 525 .long 0 526finish_tlb_load: 527 /* 528 * Clear out the software-only bits in the PTE to generate the 529 * TLB_DATA value. These are the bottom 2 bits of the RPM, the 530 * top 3 bits of the zone field, and M. 531 */ 532 li r9, 0x0ce2 533 andc r11, r11, r9 534 535 /* load the next available TLB index. */ 536 lwz r9, tlb_4xx_index@l(0) 537 addi r9, r9, 1 538 andi. r9, r9, PPC40X_TLB_SIZE - 1 539 stw r9, tlb_4xx_index@l(0) 540 541 tlbwe r11, r9, TLB_DATA /* Load TLB LO */ 542 tlbwe r10, r9, TLB_TAG /* Load TLB HI */ 543 544 /* Done...restore registers and get out of here. 545 */ 546 mfspr r9, SPRN_SPRG_SCRATCH5 547 mtspr SPRN_PID, r9 548 mtcr r12 549 mfspr r9, SPRN_SPRG_SCRATCH4 550 mfspr r12, SPRN_SPRG_SCRATCH3 551 mfspr r11, SPRN_SPRG_SCRATCH1 552 mfspr r10, SPRN_SPRG_SCRATCH0 553 rfi /* Should sync shadow TLBs */ 554 b . /* prevent prefetch past rfi */ 555 556/* This is where the main kernel code starts. 557 */ 558start_here: 559 560 /* ptr to current */ 561 lis r2,init_task@h 562 ori r2,r2,init_task@l 563 564 /* ptr to phys current thread */ 565 tophys(r4,r2) 566 addi r4,r4,THREAD /* init task's THREAD */ 567 mtspr SPRN_SPRG_THREAD,r4 568 569 /* stack */ 570 lis r1,init_thread_union@ha 571 addi r1,r1,init_thread_union@l 572 li r0,0 573 stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1) 574 575 bl early_init /* We have to do this with MMU on */ 576 577/* 578 * Decide what sort of machine this is and initialize the MMU. 579 */ 580#ifdef CONFIG_KASAN 581 bl kasan_early_init 582#endif 583 li r3,0 584 mr r4,r31 585 bl machine_init 586 bl MMU_init 587 588/* Go back to running unmapped so we can load up new values 589 * and change to using our exception vectors. 590 * On the 4xx, all we have to do is invalidate the TLB to clear 591 * the old 16M byte TLB mappings. 592 */ 593 lis r4,2f@h 594 ori r4,r4,2f@l 595 tophys(r4,r4) 596 lis r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@h 597 ori r3,r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@l 598 mtspr SPRN_SRR0,r4 599 mtspr SPRN_SRR1,r3 600 rfi 601 b . /* prevent prefetch past rfi */ 602 603/* Load up the kernel context */ 6042: 605 sync /* Flush to memory before changing TLB */ 606 tlbia 607 isync /* Flush shadow TLBs */ 608 609 /* set up the PTE pointers for the Abatron bdiGDB. 610 */ 611 lis r6, swapper_pg_dir@h 612 ori r6, r6, swapper_pg_dir@l 613 lis r5, abatron_pteptrs@h 614 ori r5, r5, abatron_pteptrs@l 615 stw r5, 0xf0(0) /* Must match your Abatron config file */ 616 tophys(r5,r5) 617 stw r6, 0(r5) 618 619/* Now turn on the MMU for real! */ 620 lis r4,MSR_KERNEL@h 621 ori r4,r4,MSR_KERNEL@l 622 lis r3,start_kernel@h 623 ori r3,r3,start_kernel@l 624 mtspr SPRN_SRR0,r3 625 mtspr SPRN_SRR1,r4 626 rfi /* enable MMU and jump to start_kernel */ 627 b . /* prevent prefetch past rfi */ 628 629/* Set up the initial MMU state so we can do the first level of 630 * kernel initialization. This maps the first 32 MBytes of memory 1:1 631 * virtual to physical and more importantly sets the cache mode. 632 */ 633initial_mmu: 634 tlbia /* Invalidate all TLB entries */ 635 isync 636 637 /* We should still be executing code at physical address 0x0000xxxx 638 * at this point. However, start_here is at virtual address 639 * 0xC000xxxx. So, set up a TLB mapping to cover this once 640 * translation is enabled. 641 */ 642 643 lis r3,KERNELBASE@h /* Load the kernel virtual address */ 644 ori r3,r3,KERNELBASE@l 645 tophys(r4,r3) /* Load the kernel physical address */ 646 647 iccci r0,r3 /* Invalidate the i-cache before use */ 648 649 /* Load the kernel PID. 650 */ 651 li r0,0 652 mtspr SPRN_PID,r0 653 sync 654 655 /* Configure and load one entry into TLB slots 63 */ 656 clrrwi r4,r4,10 /* Mask off the real page number */ 657 ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */ 658 659 clrrwi r3,r3,10 /* Mask off the effective page number */ 660 ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M)) 661 662 li r0,63 /* TLB slot 63 */ 663 664 tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */ 665 tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */ 666 667 li r0,62 /* TLB slot 62 */ 668 addis r4,r4,SZ_16M@h 669 addis r3,r3,SZ_16M@h 670 tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */ 671 tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */ 672 673 isync 674 675 /* Establish the exception vector base 676 */ 677 lis r4,KERNELBASE@h /* EVPR only uses the high 16-bits */ 678 tophys(r0,r4) /* Use the physical address */ 679 mtspr SPRN_EVPR,r0 680 681 blr 682 683_GLOBAL(abort) 684 mfspr r13,SPRN_DBCR0 685 oris r13,r13,DBCR0_RST_SYSTEM@h 686 mtspr SPRN_DBCR0,r13 687 688_GLOBAL(set_context) 689 690#ifdef CONFIG_BDI_SWITCH 691 /* Context switch the PTE pointer for the Abatron BDI2000. 692 * The PGDIR is the second parameter. 693 */ 694 lis r5, abatron_pteptrs@ha 695 stw r4, abatron_pteptrs@l + 0x4(r5) 696#endif 697 sync 698 mtspr SPRN_PID,r3 699 isync /* Need an isync to flush shadow */ 700 /* TLBs after changing PID */ 701 blr 702 703/* We put a few things here that have to be page-aligned. This stuff 704 * goes at the beginning of the data segment, which is page-aligned. 705 */ 706 .data 707 .align 12 708 .globl sdata 709sdata: 710 .globl empty_zero_page 711empty_zero_page: 712 .space 4096 713EXPORT_SYMBOL(empty_zero_page) 714 .globl swapper_pg_dir 715swapper_pg_dir: 716 .space PGD_TABLE_SIZE 717 718/* Room for two PTE pointers, usually the kernel and current user pointers 719 * to their respective root page table. 720 */ 721abatron_pteptrs: 722 .space 8 723