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 <asm/processor.h> 31#include <asm/page.h> 32#include <asm/mmu.h> 33#include <asm/cputable.h> 34#include <asm/thread_info.h> 35#include <asm/ppc_asm.h> 36#include <asm/asm-offsets.h> 37#include <asm/ptrace.h> 38#include <asm/export.h> 39 40#include "head_32.h" 41 42/* As with the other PowerPC ports, it is expected that when code 43 * execution begins here, the following registers contain valid, yet 44 * optional, information: 45 * 46 * r3 - Board info structure pointer (DRAM, frequency, MAC address, etc.) 47 * r4 - Starting address of the init RAM disk 48 * r5 - Ending address of the init RAM disk 49 * r6 - Start of kernel command line string (e.g. "mem=96m") 50 * r7 - End of kernel command line string 51 * 52 * This is all going to change RSN when we add bi_recs....... -- Dan 53 */ 54 __HEAD 55_ENTRY(_stext); 56_ENTRY(_start); 57 58 mr r31,r3 /* save device tree ptr */ 59 60 /* We have to turn on the MMU right away so we get cache modes 61 * set correctly. 62 */ 63 bl initial_mmu 64 65/* We now have the lower 16 Meg mapped into TLB entries, and the caches 66 * ready to work. 67 */ 68turn_on_mmu: 69 lis r0,MSR_KERNEL@h 70 ori r0,r0,MSR_KERNEL@l 71 mtspr SPRN_SRR1,r0 72 lis r0,start_here@h 73 ori r0,r0,start_here@l 74 mtspr SPRN_SRR0,r0 75 rfi /* enables MMU */ 76 b . /* prevent prefetch past rfi */ 77 78/* 79 * This area is used for temporarily saving registers during the 80 * critical exception prolog. 81 */ 82 . = 0xc0 83crit_save: 84_ENTRY(crit_r10) 85 .space 4 86_ENTRY(crit_r11) 87 .space 4 88_ENTRY(crit_srr0) 89 .space 4 90_ENTRY(crit_srr1) 91 .space 4 92_ENTRY(saved_ksp_limit) 93 .space 4 94 95/* 96 * Exception prolog for critical exceptions. This is a little different 97 * from the normal exception prolog above since a critical exception 98 * can potentially occur at any point during normal exception processing. 99 * Thus we cannot use the same SPRG registers as the normal prolog above. 100 * Instead we use a couple of words of memory at low physical addresses. 101 * This is OK since we don't support SMP on these processors. 102 */ 103#define CRITICAL_EXCEPTION_PROLOG \ 104 stw r10,crit_r10@l(0); /* save two registers to work with */\ 105 stw r11,crit_r11@l(0); \ 106 mfcr r10; /* save CR in r10 for now */\ 107 mfspr r11,SPRN_SRR3; /* check whether user or kernel */\ 108 andi. r11,r11,MSR_PR; \ 109 lis r11,critirq_ctx@ha; \ 110 tophys(r11,r11); \ 111 lwz r11,critirq_ctx@l(r11); \ 112 beq 1f; \ 113 /* COMING FROM USER MODE */ \ 114 mfspr r11,SPRN_SPRG_THREAD; /* if from user, start at top of */\ 115 lwz r11,TASK_STACK-THREAD(r11); /* this thread's kernel stack */\ 1161: addi r11,r11,THREAD_SIZE-INT_FRAME_SIZE; /* Alloc an excpt frm */\ 117 tophys(r11,r11); \ 118 stw r10,_CCR(r11); /* save various registers */\ 119 stw r12,GPR12(r11); \ 120 stw r9,GPR9(r11); \ 121 mflr r10; \ 122 stw r10,_LINK(r11); \ 123 mfspr r12,SPRN_DEAR; /* save DEAR and ESR in the frame */\ 124 stw r12,_DEAR(r11); /* since they may have had stuff */\ 125 mfspr r9,SPRN_ESR; /* in them at the point where the */\ 126 stw r9,_ESR(r11); /* exception was taken */\ 127 mfspr r12,SPRN_SRR2; \ 128 stw r1,GPR1(r11); \ 129 mfspr r9,SPRN_SRR3; \ 130 stw r1,0(r11); \ 131 tovirt(r1,r11); \ 132 rlwinm r9,r9,0,14,12; /* clear MSR_WE (necessary?) */\ 133 stw r0,GPR0(r11); \ 134 lis r10, STACK_FRAME_REGS_MARKER@ha; /* exception frame marker */\ 135 addi r10, r10, STACK_FRAME_REGS_MARKER@l; \ 136 stw r10, 8(r11); \ 137 SAVE_4GPRS(3, r11); \ 138 SAVE_2GPRS(7, r11) 139 140 /* 141 * State at this point: 142 * r9 saved in stack frame, now saved SRR3 & ~MSR_WE 143 * r10 saved in crit_r10 and in stack frame, trashed 144 * r11 saved in crit_r11 and in stack frame, 145 * now phys stack/exception frame pointer 146 * r12 saved in stack frame, now saved SRR2 147 * CR saved in stack frame, CR0.EQ = !SRR3.PR 148 * LR, DEAR, ESR in stack frame 149 * r1 saved in stack frame, now virt stack/excframe pointer 150 * r0, r3-r8 saved in stack frame 151 */ 152 153/* 154 * Exception vectors. 155 */ 156#define CRITICAL_EXCEPTION(n, label, hdlr) \ 157 START_EXCEPTION(n, label); \ 158 CRITICAL_EXCEPTION_PROLOG; \ 159 addi r3,r1,STACK_FRAME_OVERHEAD; \ 160 EXC_XFER_TEMPLATE(hdlr, n+2, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \ 161 crit_transfer_to_handler, ret_from_crit_exc) 162 163/* 164 * 0x0100 - Critical Interrupt Exception 165 */ 166 CRITICAL_EXCEPTION(0x0100, CriticalInterrupt, unknown_exception) 167 168/* 169 * 0x0200 - Machine Check Exception 170 */ 171 CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception) 172 173/* 174 * 0x0300 - Data Storage Exception 175 * This happens for just a few reasons. U0 set (but we don't do that), 176 * or zone protection fault (user violation, write to protected page). 177 * The other Data TLB exceptions bail out to this point 178 * if they can't resolve the lightweight TLB fault. 179 */ 180 START_EXCEPTION(0x0300, DataStorage) 181 EXCEPTION_PROLOG 182 mfspr r5, SPRN_ESR /* Grab the ESR, save it */ 183 stw r5, _ESR(r11) 184 mfspr r4, SPRN_DEAR /* Grab the DEAR, save it */ 185 stw r4, _DEAR(r11) 186 EXC_XFER_LITE(0x300, handle_page_fault) 187 188/* 189 * 0x0400 - Instruction Storage Exception 190 * This is caused by a fetch from non-execute or guarded pages. 191 */ 192 START_EXCEPTION(0x0400, InstructionAccess) 193 EXCEPTION_PROLOG 194 li r5,0 195 stw r5, _ESR(r11) /* Zero ESR */ 196 stw r12, _DEAR(r11) /* SRR0 as DEAR */ 197 EXC_XFER_LITE(0x400, handle_page_fault) 198 199/* 0x0500 - External Interrupt Exception */ 200 EXCEPTION(0x0500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE) 201 202/* 0x0600 - Alignment Exception */ 203 START_EXCEPTION(0x0600, Alignment) 204 EXCEPTION_PROLOG 205 mfspr r4,SPRN_DEAR /* Grab the DEAR and save it */ 206 stw r4,_DEAR(r11) 207 addi r3,r1,STACK_FRAME_OVERHEAD 208 EXC_XFER_STD(0x600, alignment_exception) 209 210/* 0x0700 - Program Exception */ 211 START_EXCEPTION(0x0700, ProgramCheck) 212 EXCEPTION_PROLOG 213 mfspr r4,SPRN_ESR /* Grab the ESR and save it */ 214 stw r4,_ESR(r11) 215 addi r3,r1,STACK_FRAME_OVERHEAD 216 EXC_XFER_STD(0x700, program_check_exception) 217 218 EXCEPTION(0x0800, Trap_08, unknown_exception, EXC_XFER_STD) 219 EXCEPTION(0x0900, Trap_09, unknown_exception, EXC_XFER_STD) 220 EXCEPTION(0x0A00, Trap_0A, unknown_exception, EXC_XFER_STD) 221 EXCEPTION(0x0B00, Trap_0B, unknown_exception, EXC_XFER_STD) 222 223/* 0x0C00 - System Call Exception */ 224 START_EXCEPTION(0x0C00, SystemCall) 225 SYSCALL_ENTRY 0xc00 226/* Trap_0D is commented out to get more space for system call exception */ 227 228/* EXCEPTION(0x0D00, Trap_0D, unknown_exception, EXC_XFER_STD) */ 229 EXCEPTION(0x0E00, Trap_0E, unknown_exception, EXC_XFER_STD) 230 EXCEPTION(0x0F00, Trap_0F, unknown_exception, EXC_XFER_STD) 231 232/* 0x1000 - Programmable Interval Timer (PIT) Exception */ 233 . = 0x1000 234 b Decrementer 235 236/* 0x1010 - Fixed Interval Timer (FIT) Exception 237*/ 238 . = 0x1010 239 b FITException 240 241/* 0x1020 - Watchdog Timer (WDT) Exception 242*/ 243 . = 0x1020 244 b WDTException 245 246/* 0x1100 - Data TLB Miss Exception 247 * As the name implies, translation is not in the MMU, so search the 248 * page tables and fix it. The only purpose of this function is to 249 * load TLB entries from the page table if they exist. 250 */ 251 START_EXCEPTION(0x1100, DTLBMiss) 252 mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */ 253 mtspr SPRN_SPRG_SCRATCH1, r11 254 mtspr SPRN_SPRG_SCRATCH3, r12 255 mtspr SPRN_SPRG_SCRATCH4, r9 256 mfcr r12 257 mfspr r9, SPRN_PID 258 mtspr SPRN_SPRG_SCRATCH5, r9 259 mfspr r10, SPRN_DEAR /* Get faulting address */ 260 261 /* If we are faulting a kernel address, we have to use the 262 * kernel page tables. 263 */ 264 lis r11, PAGE_OFFSET@h 265 cmplw r10, r11 266 blt+ 3f 267 lis r11, swapper_pg_dir@h 268 ori r11, r11, swapper_pg_dir@l 269 li r9, 0 270 mtspr SPRN_PID, r9 /* TLB will have 0 TID */ 271 b 4f 272 273 /* Get the PGD for the current thread. 274 */ 2753: 276 mfspr r11,SPRN_SPRG_THREAD 277 lwz r11,PGDIR(r11) 2784: 279 tophys(r11, r11) 280 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ 281 lwz r11, 0(r11) /* Get L1 entry */ 282 andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */ 283 beq 2f /* Bail if no table */ 284 285 rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */ 286 lwz r11, 0(r11) /* Get Linux PTE */ 287 li r9, _PAGE_PRESENT | _PAGE_ACCESSED 288 andc. r9, r9, r11 /* Check permission */ 289 bne 5f 290 291 rlwinm r9, r11, 1, _PAGE_RW /* dirty => rw */ 292 and r9, r9, r11 /* hwwrite = dirty & rw */ 293 rlwimi r11, r9, 0, _PAGE_RW /* replace rw by hwwrite */ 294 295 /* Create TLB tag. This is the faulting address plus a static 296 * set of bits. These are size, valid, E, U0. 297 */ 298 li r9, 0x00c0 299 rlwimi r10, r9, 0, 20, 31 300 301 b finish_tlb_load 302 3032: /* Check for possible large-page pmd entry */ 304 rlwinm. r9, r11, 2, 22, 24 305 beq 5f 306 307 /* Create TLB tag. This is the faulting address, plus a static 308 * set of bits (valid, E, U0) plus the size from the PMD. 309 */ 310 ori r9, r9, 0x40 311 rlwimi r10, r9, 0, 20, 31 312 313 b finish_tlb_load 314 3155: 316 /* The bailout. Restore registers to pre-exception conditions 317 * and call the heavyweights to help us out. 318 */ 319 mfspr r9, SPRN_SPRG_SCRATCH5 320 mtspr SPRN_PID, r9 321 mtcr r12 322 mfspr r9, SPRN_SPRG_SCRATCH4 323 mfspr r12, SPRN_SPRG_SCRATCH3 324 mfspr r11, SPRN_SPRG_SCRATCH1 325 mfspr r10, SPRN_SPRG_SCRATCH0 326 b DataStorage 327 328/* 0x1200 - Instruction TLB Miss Exception 329 * Nearly the same as above, except we get our information from different 330 * registers and bailout to a different point. 331 */ 332 START_EXCEPTION(0x1200, ITLBMiss) 333 mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */ 334 mtspr SPRN_SPRG_SCRATCH1, r11 335 mtspr SPRN_SPRG_SCRATCH3, r12 336 mtspr SPRN_SPRG_SCRATCH4, r9 337 mfcr r12 338 mfspr r9, SPRN_PID 339 mtspr SPRN_SPRG_SCRATCH5, r9 340 mfspr r10, SPRN_SRR0 /* Get faulting address */ 341 342 /* If we are faulting a kernel address, we have to use the 343 * kernel page tables. 344 */ 345 lis r11, PAGE_OFFSET@h 346 cmplw r10, r11 347 blt+ 3f 348 lis r11, swapper_pg_dir@h 349 ori r11, r11, swapper_pg_dir@l 350 li r9, 0 351 mtspr SPRN_PID, r9 /* TLB will have 0 TID */ 352 b 4f 353 354 /* Get the PGD for the current thread. 355 */ 3563: 357 mfspr r11,SPRN_SPRG_THREAD 358 lwz r11,PGDIR(r11) 3594: 360 tophys(r11, r11) 361 rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ 362 lwz r11, 0(r11) /* Get L1 entry */ 363 andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */ 364 beq 2f /* Bail if no table */ 365 366 rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */ 367 lwz r11, 0(r11) /* Get Linux PTE */ 368 li r9, _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC 369 andc. r9, r9, r11 /* Check permission */ 370 bne 5f 371 372 rlwinm r9, r11, 1, _PAGE_RW /* dirty => rw */ 373 and r9, r9, r11 /* hwwrite = dirty & rw */ 374 rlwimi r11, r9, 0, _PAGE_RW /* replace rw by hwwrite */ 375 376 /* Create TLB tag. This is the faulting address plus a static 377 * set of bits. These are size, valid, E, U0. 378 */ 379 li r9, 0x00c0 380 rlwimi r10, r9, 0, 20, 31 381 382 b finish_tlb_load 383 3842: /* Check for possible large-page pmd entry */ 385 rlwinm. r9, r11, 2, 22, 24 386 beq 5f 387 388 /* Create TLB tag. This is the faulting address, plus a static 389 * set of bits (valid, E, U0) plus the size from the PMD. 390 */ 391 ori r9, r9, 0x40 392 rlwimi r10, r9, 0, 20, 31 393 394 b finish_tlb_load 395 3965: 397 /* The bailout. Restore registers to pre-exception conditions 398 * and call the heavyweights to help us out. 399 */ 400 mfspr r9, SPRN_SPRG_SCRATCH5 401 mtspr SPRN_PID, r9 402 mtcr r12 403 mfspr r9, SPRN_SPRG_SCRATCH4 404 mfspr r12, SPRN_SPRG_SCRATCH3 405 mfspr r11, SPRN_SPRG_SCRATCH1 406 mfspr r10, SPRN_SPRG_SCRATCH0 407 b InstructionAccess 408 409 EXCEPTION(0x1300, Trap_13, unknown_exception, EXC_XFER_STD) 410 EXCEPTION(0x1400, Trap_14, unknown_exception, EXC_XFER_STD) 411 EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_STD) 412 EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_STD) 413 EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_STD) 414 EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_STD) 415 EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_STD) 416 EXCEPTION(0x1A00, Trap_1A, unknown_exception, EXC_XFER_STD) 417 EXCEPTION(0x1B00, Trap_1B, unknown_exception, EXC_XFER_STD) 418 EXCEPTION(0x1C00, Trap_1C, unknown_exception, EXC_XFER_STD) 419 EXCEPTION(0x1D00, Trap_1D, unknown_exception, EXC_XFER_STD) 420 EXCEPTION(0x1E00, Trap_1E, unknown_exception, EXC_XFER_STD) 421 EXCEPTION(0x1F00, Trap_1F, unknown_exception, EXC_XFER_STD) 422 423/* Check for a single step debug exception while in an exception 424 * handler before state has been saved. This is to catch the case 425 * where an instruction that we are trying to single step causes 426 * an exception (eg ITLB/DTLB miss) and thus the first instruction of 427 * the exception handler generates a single step debug exception. 428 * 429 * If we get a debug trap on the first instruction of an exception handler, 430 * we reset the MSR_DE in the _exception handler's_ MSR (the debug trap is 431 * a critical exception, so we are using SPRN_CSRR1 to manipulate the MSR). 432 * The exception handler was handling a non-critical interrupt, so it will 433 * save (and later restore) the MSR via SPRN_SRR1, which will still have 434 * the MSR_DE bit set. 435 */ 436 /* 0x2000 - Debug Exception */ 437 START_EXCEPTION(0x2000, DebugTrap) 438 CRITICAL_EXCEPTION_PROLOG 439 440 /* 441 * If this is a single step or branch-taken exception in an 442 * exception entry sequence, it was probably meant to apply to 443 * the code where the exception occurred (since exception entry 444 * doesn't turn off DE automatically). We simulate the effect 445 * of turning off DE on entry to an exception handler by turning 446 * off DE in the SRR3 value and clearing the debug status. 447 */ 448 mfspr r10,SPRN_DBSR /* check single-step/branch taken */ 449 andis. r10,r10,DBSR_IC@h 450 beq+ 2f 451 452 andi. r10,r9,MSR_IR|MSR_PR /* check supervisor + MMU off */ 453 beq 1f /* branch and fix it up */ 454 455 mfspr r10,SPRN_SRR2 /* Faulting instruction address */ 456 cmplwi r10,0x2100 457 bgt+ 2f /* address above exception vectors */ 458 459 /* here it looks like we got an inappropriate debug exception. */ 4601: rlwinm r9,r9,0,~MSR_DE /* clear DE in the SRR3 value */ 461 lis r10,DBSR_IC@h /* clear the IC event */ 462 mtspr SPRN_DBSR,r10 463 /* restore state and get out */ 464 lwz r10,_CCR(r11) 465 lwz r0,GPR0(r11) 466 lwz r1,GPR1(r11) 467 mtcrf 0x80,r10 468 mtspr SPRN_SRR2,r12 469 mtspr SPRN_SRR3,r9 470 lwz r9,GPR9(r11) 471 lwz r12,GPR12(r11) 472 lwz r10,crit_r10@l(0) 473 lwz r11,crit_r11@l(0) 474 rfci 475 b . 476 477 /* continue normal handling for a critical exception... */ 4782: mfspr r4,SPRN_DBSR 479 stw r4,_ESR(r11) /* DebugException takes DBSR in _ESR */ 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 16 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 isync 668 669 /* Establish the exception vector base 670 */ 671 lis r4,KERNELBASE@h /* EVPR only uses the high 16-bits */ 672 tophys(r0,r4) /* Use the physical address */ 673 mtspr SPRN_EVPR,r0 674 675 blr 676 677_GLOBAL(abort) 678 mfspr r13,SPRN_DBCR0 679 oris r13,r13,DBCR0_RST_SYSTEM@h 680 mtspr SPRN_DBCR0,r13 681 682_GLOBAL(set_context) 683 684#ifdef CONFIG_BDI_SWITCH 685 /* Context switch the PTE pointer for the Abatron BDI2000. 686 * The PGDIR is the second parameter. 687 */ 688 lis r5, abatron_pteptrs@ha 689 stw r4, abatron_pteptrs@l + 0x4(r5) 690#endif 691 sync 692 mtspr SPRN_PID,r3 693 isync /* Need an isync to flush shadow */ 694 /* TLBs after changing PID */ 695 blr 696 697/* We put a few things here that have to be page-aligned. This stuff 698 * goes at the beginning of the data segment, which is page-aligned. 699 */ 700 .data 701 .align 12 702 .globl sdata 703sdata: 704 .globl empty_zero_page 705empty_zero_page: 706 .space 4096 707EXPORT_SYMBOL(empty_zero_page) 708 .globl swapper_pg_dir 709swapper_pg_dir: 710 .space PGD_TABLE_SIZE 711 712/* Room for two PTE pointers, usually the kernel and current user pointers 713 * to their respective root page table. 714 */ 715abatron_pteptrs: 716 .space 8 717