1/* 2 * linux/arch/arm/kernel/head.S 3 * 4 * Copyright (C) 1994-2002 Russell King 5 * Copyright (c) 2003 ARM Limited 6 * All Rights Reserved 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 * 12 * Kernel startup code for all 32-bit CPUs 13 */ 14#include <linux/linkage.h> 15#include <linux/init.h> 16 17#include <asm/assembler.h> 18#include <asm/cp15.h> 19#include <asm/domain.h> 20#include <asm/ptrace.h> 21#include <asm/asm-offsets.h> 22#include <asm/memory.h> 23#include <asm/thread_info.h> 24#include <asm/pgtable.h> 25 26#if defined(CONFIG_DEBUG_LL) && !defined(CONFIG_DEBUG_SEMIHOSTING) 27#include CONFIG_DEBUG_LL_INCLUDE 28#endif 29 30/* 31 * swapper_pg_dir is the virtual address of the initial page table. 32 * We place the page tables 16K below KERNEL_RAM_VADDR. Therefore, we must 33 * make sure that KERNEL_RAM_VADDR is correctly set. Currently, we expect 34 * the least significant 16 bits to be 0x8000, but we could probably 35 * relax this restriction to KERNEL_RAM_VADDR >= PAGE_OFFSET + 0x4000. 36 */ 37#define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET) 38#if (KERNEL_RAM_VADDR & 0xffff) != 0x8000 39#error KERNEL_RAM_VADDR must start at 0xXXXX8000 40#endif 41 42#ifdef CONFIG_ARM_LPAE 43 /* LPAE requires an additional page for the PGD */ 44#define PG_DIR_SIZE 0x5000 45#define PMD_ORDER 3 46#else 47#define PG_DIR_SIZE 0x4000 48#define PMD_ORDER 2 49#endif 50 51 .globl swapper_pg_dir 52 .equ swapper_pg_dir, KERNEL_RAM_VADDR - PG_DIR_SIZE 53 54 .macro pgtbl, rd, phys 55 add \rd, \phys, #TEXT_OFFSET - PG_DIR_SIZE 56 .endm 57 58/* 59 * Kernel startup entry point. 60 * --------------------------- 61 * 62 * This is normally called from the decompressor code. The requirements 63 * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0, 64 * r1 = machine nr, r2 = atags or dtb pointer. 65 * 66 * This code is mostly position independent, so if you link the kernel at 67 * 0xc0008000, you call this at __pa(0xc0008000). 68 * 69 * See linux/arch/arm/tools/mach-types for the complete list of machine 70 * numbers for r1. 71 * 72 * We're trying to keep crap to a minimum; DO NOT add any machine specific 73 * crap here - that's what the boot loader (or in extreme, well justified 74 * circumstances, zImage) is for. 75 */ 76 .arm 77 78 __HEAD 79ENTRY(stext) 80 81 THUMB( adr r9, BSYM(1f) ) @ Kernel is always entered in ARM. 82 THUMB( bx r9 ) @ If this is a Thumb-2 kernel, 83 THUMB( .thumb ) @ switch to Thumb now. 84 THUMB(1: ) 85 86#ifdef CONFIG_ARM_VIRT_EXT 87 bl __hyp_stub_install 88#endif 89 @ ensure svc mode and all interrupts masked 90 safe_svcmode_maskall r9 91 92 mrc p15, 0, r9, c0, c0 @ get processor id 93 bl __lookup_processor_type @ r5=procinfo r9=cpuid 94 movs r10, r5 @ invalid processor (r5=0)? 95 THUMB( it eq ) @ force fixup-able long branch encoding 96 beq __error_p @ yes, error 'p' 97 98#ifdef CONFIG_ARM_LPAE 99 mrc p15, 0, r3, c0, c1, 4 @ read ID_MMFR0 100 and r3, r3, #0xf @ extract VMSA support 101 cmp r3, #5 @ long-descriptor translation table format? 102 THUMB( it lo ) @ force fixup-able long branch encoding 103 blo __error_p @ only classic page table format 104#endif 105 106#ifndef CONFIG_XIP_KERNEL 107 adr r3, 2f 108 ldmia r3, {r4, r8} 109 sub r4, r3, r4 @ (PHYS_OFFSET - PAGE_OFFSET) 110 add r8, r8, r4 @ PHYS_OFFSET 111#else 112 ldr r8, =PHYS_OFFSET @ always constant in this case 113#endif 114 115 /* 116 * r1 = machine no, r2 = atags or dtb, 117 * r8 = phys_offset, r9 = cpuid, r10 = procinfo 118 */ 119 bl __vet_atags 120#ifdef CONFIG_SMP_ON_UP 121 bl __fixup_smp 122#endif 123#ifdef CONFIG_ARM_PATCH_PHYS_VIRT 124 bl __fixup_pv_table 125#endif 126 bl __create_page_tables 127 128 /* 129 * The following calls CPU specific code in a position independent 130 * manner. See arch/arm/mm/proc-*.S for details. r10 = base of 131 * xxx_proc_info structure selected by __lookup_processor_type 132 * above. On return, the CPU will be ready for the MMU to be 133 * turned on, and r0 will hold the CPU control register value. 134 */ 135 ldr r13, =__mmap_switched @ address to jump to after 136 @ mmu has been enabled 137 adr lr, BSYM(1f) @ return (PIC) address 138 mov r8, r4 @ set TTBR1 to swapper_pg_dir 139 ARM( add pc, r10, #PROCINFO_INITFUNC ) 140 THUMB( add r12, r10, #PROCINFO_INITFUNC ) 141 THUMB( mov pc, r12 ) 1421: b __enable_mmu 143ENDPROC(stext) 144 .ltorg 145#ifndef CONFIG_XIP_KERNEL 1462: .long . 147 .long PAGE_OFFSET 148#endif 149 150/* 151 * Setup the initial page tables. We only setup the barest 152 * amount which are required to get the kernel running, which 153 * generally means mapping in the kernel code. 154 * 155 * r8 = phys_offset, r9 = cpuid, r10 = procinfo 156 * 157 * Returns: 158 * r0, r3, r5-r7 corrupted 159 * r4 = physical page table address 160 */ 161__create_page_tables: 162 pgtbl r4, r8 @ page table address 163 164 /* 165 * Clear the swapper page table 166 */ 167 mov r0, r4 168 mov r3, #0 169 add r6, r0, #PG_DIR_SIZE 1701: str r3, [r0], #4 171 str r3, [r0], #4 172 str r3, [r0], #4 173 str r3, [r0], #4 174 teq r0, r6 175 bne 1b 176 177#ifdef CONFIG_ARM_LPAE 178 /* 179 * Build the PGD table (first level) to point to the PMD table. A PGD 180 * entry is 64-bit wide. 181 */ 182 mov r0, r4 183 add r3, r4, #0x1000 @ first PMD table address 184 orr r3, r3, #3 @ PGD block type 185 mov r6, #4 @ PTRS_PER_PGD 186 mov r7, #1 << (55 - 32) @ L_PGD_SWAPPER 1871: str r3, [r0], #4 @ set bottom PGD entry bits 188 str r7, [r0], #4 @ set top PGD entry bits 189 add r3, r3, #0x1000 @ next PMD table 190 subs r6, r6, #1 191 bne 1b 192 193 add r4, r4, #0x1000 @ point to the PMD tables 194#endif 195 196 ldr r7, [r10, #PROCINFO_MM_MMUFLAGS] @ mm_mmuflags 197 198 /* 199 * Create identity mapping to cater for __enable_mmu. 200 * This identity mapping will be removed by paging_init(). 201 */ 202 adr r0, __turn_mmu_on_loc 203 ldmia r0, {r3, r5, r6} 204 sub r0, r0, r3 @ virt->phys offset 205 add r5, r5, r0 @ phys __turn_mmu_on 206 add r6, r6, r0 @ phys __turn_mmu_on_end 207 mov r5, r5, lsr #SECTION_SHIFT 208 mov r6, r6, lsr #SECTION_SHIFT 209 2101: orr r3, r7, r5, lsl #SECTION_SHIFT @ flags + kernel base 211 str r3, [r4, r5, lsl #PMD_ORDER] @ identity mapping 212 cmp r5, r6 213 addlo r5, r5, #1 @ next section 214 blo 1b 215 216 /* 217 * Map our RAM from the start to the end of the kernel .bss section. 218 */ 219 add r0, r4, #PAGE_OFFSET >> (SECTION_SHIFT - PMD_ORDER) 220 ldr r6, =(_end - 1) 221 orr r3, r8, r7 222 add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER) 2231: str r3, [r0], #1 << PMD_ORDER 224 add r3, r3, #1 << SECTION_SHIFT 225 cmp r0, r6 226 bls 1b 227 228#ifdef CONFIG_XIP_KERNEL 229 /* 230 * Map the kernel image separately as it is not located in RAM. 231 */ 232#define XIP_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR) 233 mov r3, pc 234 mov r3, r3, lsr #SECTION_SHIFT 235 orr r3, r7, r3, lsl #SECTION_SHIFT 236 add r0, r4, #(XIP_START & 0xff000000) >> (SECTION_SHIFT - PMD_ORDER) 237 str r3, [r0, #((XIP_START & 0x00f00000) >> SECTION_SHIFT) << PMD_ORDER]! 238 ldr r6, =(_edata_loc - 1) 239 add r0, r0, #1 << PMD_ORDER 240 add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER) 2411: cmp r0, r6 242 add r3, r3, #1 << SECTION_SHIFT 243 strls r3, [r0], #1 << PMD_ORDER 244 bls 1b 245#endif 246 247 /* 248 * Then map boot params address in r2 if specified. 249 * We map 2 sections in case the ATAGs/DTB crosses a section boundary. 250 */ 251 mov r0, r2, lsr #SECTION_SHIFT 252 movs r0, r0, lsl #SECTION_SHIFT 253 subne r3, r0, r8 254 addne r3, r3, #PAGE_OFFSET 255 addne r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER) 256 orrne r6, r7, r0 257 strne r6, [r3], #1 << PMD_ORDER 258 addne r6, r6, #1 << SECTION_SHIFT 259 strne r6, [r3] 260 261#ifdef CONFIG_DEBUG_LL 262#if !defined(CONFIG_DEBUG_ICEDCC) && !defined(CONFIG_DEBUG_SEMIHOSTING) 263 /* 264 * Map in IO space for serial debugging. 265 * This allows debug messages to be output 266 * via a serial console before paging_init. 267 */ 268 addruart r7, r3, r0 269 270 mov r3, r3, lsr #SECTION_SHIFT 271 mov r3, r3, lsl #PMD_ORDER 272 273 add r0, r4, r3 274 mov r3, r7, lsr #SECTION_SHIFT 275 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags 276 orr r3, r7, r3, lsl #SECTION_SHIFT 277#ifdef CONFIG_ARM_LPAE 278 mov r7, #1 << (54 - 32) @ XN 279#else 280 orr r3, r3, #PMD_SECT_XN 281#endif 282 str r3, [r0], #4 283#ifdef CONFIG_ARM_LPAE 284 str r7, [r0], #4 285#endif 286 287#else /* CONFIG_DEBUG_ICEDCC || CONFIG_DEBUG_SEMIHOSTING */ 288 /* we don't need any serial debugging mappings */ 289 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags 290#endif 291 292#if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS) 293 /* 294 * If we're using the NetWinder or CATS, we also need to map 295 * in the 16550-type serial port for the debug messages 296 */ 297 add r0, r4, #0xff000000 >> (SECTION_SHIFT - PMD_ORDER) 298 orr r3, r7, #0x7c000000 299 str r3, [r0] 300#endif 301#ifdef CONFIG_ARCH_RPC 302 /* 303 * Map in screen at 0x02000000 & SCREEN2_BASE 304 * Similar reasons here - for debug. This is 305 * only for Acorn RiscPC architectures. 306 */ 307 add r0, r4, #0x02000000 >> (SECTION_SHIFT - PMD_ORDER) 308 orr r3, r7, #0x02000000 309 str r3, [r0] 310 add r0, r4, #0xd8000000 >> (SECTION_SHIFT - PMD_ORDER) 311 str r3, [r0] 312#endif 313#endif 314#ifdef CONFIG_ARM_LPAE 315 sub r4, r4, #0x1000 @ point to the PGD table 316#endif 317 mov pc, lr 318ENDPROC(__create_page_tables) 319 .ltorg 320 .align 321__turn_mmu_on_loc: 322 .long . 323 .long __turn_mmu_on 324 .long __turn_mmu_on_end 325 326#if defined(CONFIG_SMP) 327 __CPUINIT 328ENTRY(secondary_startup) 329 /* 330 * Common entry point for secondary CPUs. 331 * 332 * Ensure that we're in SVC mode, and IRQs are disabled. Lookup 333 * the processor type - there is no need to check the machine type 334 * as it has already been validated by the primary processor. 335 */ 336#ifdef CONFIG_ARM_VIRT_EXT 337 bl __hyp_stub_install_secondary 338#endif 339 safe_svcmode_maskall r9 340 341 mrc p15, 0, r9, c0, c0 @ get processor id 342 bl __lookup_processor_type 343 movs r10, r5 @ invalid processor? 344 moveq r0, #'p' @ yes, error 'p' 345 THUMB( it eq ) @ force fixup-able long branch encoding 346 beq __error_p 347 348 /* 349 * Use the page tables supplied from __cpu_up. 350 */ 351 adr r4, __secondary_data 352 ldmia r4, {r5, r7, r12} @ address to jump to after 353 sub lr, r4, r5 @ mmu has been enabled 354 ldr r4, [r7, lr] @ get secondary_data.pgdir 355 add r7, r7, #4 356 ldr r8, [r7, lr] @ get secondary_data.swapper_pg_dir 357 adr lr, BSYM(__enable_mmu) @ return address 358 mov r13, r12 @ __secondary_switched address 359 ARM( add pc, r10, #PROCINFO_INITFUNC ) @ initialise processor 360 @ (return control reg) 361 THUMB( add r12, r10, #PROCINFO_INITFUNC ) 362 THUMB( mov pc, r12 ) 363ENDPROC(secondary_startup) 364 365 /* 366 * r6 = &secondary_data 367 */ 368ENTRY(__secondary_switched) 369 ldr sp, [r7, #4] @ get secondary_data.stack 370 mov fp, #0 371 b secondary_start_kernel 372ENDPROC(__secondary_switched) 373 374 .align 375 376 .type __secondary_data, %object 377__secondary_data: 378 .long . 379 .long secondary_data 380 .long __secondary_switched 381#endif /* defined(CONFIG_SMP) */ 382 383 384 385/* 386 * Setup common bits before finally enabling the MMU. Essentially 387 * this is just loading the page table pointer and domain access 388 * registers. 389 * 390 * r0 = cp#15 control register 391 * r1 = machine ID 392 * r2 = atags or dtb pointer 393 * r4 = page table pointer 394 * r9 = processor ID 395 * r13 = *virtual* address to jump to upon completion 396 */ 397__enable_mmu: 398#if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6 399 orr r0, r0, #CR_A 400#else 401 bic r0, r0, #CR_A 402#endif 403#ifdef CONFIG_CPU_DCACHE_DISABLE 404 bic r0, r0, #CR_C 405#endif 406#ifdef CONFIG_CPU_BPREDICT_DISABLE 407 bic r0, r0, #CR_Z 408#endif 409#ifdef CONFIG_CPU_ICACHE_DISABLE 410 bic r0, r0, #CR_I 411#endif 412#ifdef CONFIG_ARM_LPAE 413 mov r5, #0 414 mcrr p15, 0, r4, r5, c2 @ load TTBR0 415#else 416 mov r5, #(domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \ 417 domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \ 418 domain_val(DOMAIN_TABLE, DOMAIN_MANAGER) | \ 419 domain_val(DOMAIN_IO, DOMAIN_CLIENT)) 420 mcr p15, 0, r5, c3, c0, 0 @ load domain access register 421 mcr p15, 0, r4, c2, c0, 0 @ load page table pointer 422#endif 423 b __turn_mmu_on 424ENDPROC(__enable_mmu) 425 426/* 427 * Enable the MMU. This completely changes the structure of the visible 428 * memory space. You will not be able to trace execution through this. 429 * If you have an enquiry about this, *please* check the linux-arm-kernel 430 * mailing list archives BEFORE sending another post to the list. 431 * 432 * r0 = cp#15 control register 433 * r1 = machine ID 434 * r2 = atags or dtb pointer 435 * r9 = processor ID 436 * r13 = *virtual* address to jump to upon completion 437 * 438 * other registers depend on the function called upon completion 439 */ 440 .align 5 441 .pushsection .idmap.text, "ax" 442ENTRY(__turn_mmu_on) 443 mov r0, r0 444 instr_sync 445 mcr p15, 0, r0, c1, c0, 0 @ write control reg 446 mrc p15, 0, r3, c0, c0, 0 @ read id reg 447 instr_sync 448 mov r3, r3 449 mov r3, r13 450 mov pc, r3 451__turn_mmu_on_end: 452ENDPROC(__turn_mmu_on) 453 .popsection 454 455 456#ifdef CONFIG_SMP_ON_UP 457 __INIT 458__fixup_smp: 459 and r3, r9, #0x000f0000 @ architecture version 460 teq r3, #0x000f0000 @ CPU ID supported? 461 bne __fixup_smp_on_up @ no, assume UP 462 463 bic r3, r9, #0x00ff0000 464 bic r3, r3, #0x0000000f @ mask 0xff00fff0 465 mov r4, #0x41000000 466 orr r4, r4, #0x0000b000 467 orr r4, r4, #0x00000020 @ val 0x4100b020 468 teq r3, r4 @ ARM 11MPCore? 469 moveq pc, lr @ yes, assume SMP 470 471 mrc p15, 0, r0, c0, c0, 5 @ read MPIDR 472 and r0, r0, #0xc0000000 @ multiprocessing extensions and 473 teq r0, #0x80000000 @ not part of a uniprocessor system? 474 moveq pc, lr @ yes, assume SMP 475 476__fixup_smp_on_up: 477 adr r0, 1f 478 ldmia r0, {r3 - r5} 479 sub r3, r0, r3 480 add r4, r4, r3 481 add r5, r5, r3 482 b __do_fixup_smp_on_up 483ENDPROC(__fixup_smp) 484 485 .align 4861: .word . 487 .word __smpalt_begin 488 .word __smpalt_end 489 490 .pushsection .data 491 .globl smp_on_up 492smp_on_up: 493 ALT_SMP(.long 1) 494 ALT_UP(.long 0) 495 .popsection 496#endif 497 498 .text 499__do_fixup_smp_on_up: 500 cmp r4, r5 501 movhs pc, lr 502 ldmia r4!, {r0, r6} 503 ARM( str r6, [r0, r3] ) 504 THUMB( add r0, r0, r3 ) 505#ifdef __ARMEB__ 506 THUMB( mov r6, r6, ror #16 ) @ Convert word order for big-endian. 507#endif 508 THUMB( strh r6, [r0], #2 ) @ For Thumb-2, store as two halfwords 509 THUMB( mov r6, r6, lsr #16 ) @ to be robust against misaligned r3. 510 THUMB( strh r6, [r0] ) 511 b __do_fixup_smp_on_up 512ENDPROC(__do_fixup_smp_on_up) 513 514ENTRY(fixup_smp) 515 stmfd sp!, {r4 - r6, lr} 516 mov r4, r0 517 add r5, r0, r1 518 mov r3, #0 519 bl __do_fixup_smp_on_up 520 ldmfd sp!, {r4 - r6, pc} 521ENDPROC(fixup_smp) 522 523#ifdef CONFIG_ARM_PATCH_PHYS_VIRT 524 525/* __fixup_pv_table - patch the stub instructions with the delta between 526 * PHYS_OFFSET and PAGE_OFFSET, which is assumed to be 16MiB aligned and 527 * can be expressed by an immediate shifter operand. The stub instruction 528 * has a form of '(add|sub) rd, rn, #imm'. 529 */ 530 __HEAD 531__fixup_pv_table: 532 adr r0, 1f 533 ldmia r0, {r3-r5, r7} 534 sub r3, r0, r3 @ PHYS_OFFSET - PAGE_OFFSET 535 add r4, r4, r3 @ adjust table start address 536 add r5, r5, r3 @ adjust table end address 537 add r7, r7, r3 @ adjust __pv_phys_offset address 538 str r8, [r7] @ save computed PHYS_OFFSET to __pv_phys_offset 539 mov r6, r3, lsr #24 @ constant for add/sub instructions 540 teq r3, r6, lsl #24 @ must be 16MiB aligned 541THUMB( it ne @ cross section branch ) 542 bne __error 543 str r6, [r7, #4] @ save to __pv_offset 544 b __fixup_a_pv_table 545ENDPROC(__fixup_pv_table) 546 547 .align 5481: .long . 549 .long __pv_table_begin 550 .long __pv_table_end 5512: .long __pv_phys_offset 552 553 .text 554__fixup_a_pv_table: 555#ifdef CONFIG_THUMB2_KERNEL 556 lsls r6, #24 557 beq 2f 558 clz r7, r6 559 lsr r6, #24 560 lsl r6, r7 561 bic r6, #0x0080 562 lsrs r7, #1 563 orrcs r6, #0x0080 564 orr r6, r6, r7, lsl #12 565 orr r6, #0x4000 566 b 2f 5671: add r7, r3 568 ldrh ip, [r7, #2] 569 and ip, 0x8f00 570 orr ip, r6 @ mask in offset bits 31-24 571 strh ip, [r7, #2] 5722: cmp r4, r5 573 ldrcc r7, [r4], #4 @ use branch for delay slot 574 bcc 1b 575 bx lr 576#else 577 b 2f 5781: ldr ip, [r7, r3] 579 bic ip, ip, #0x000000ff 580 orr ip, ip, r6 @ mask in offset bits 31-24 581 str ip, [r7, r3] 5822: cmp r4, r5 583 ldrcc r7, [r4], #4 @ use branch for delay slot 584 bcc 1b 585 mov pc, lr 586#endif 587ENDPROC(__fixup_a_pv_table) 588 589ENTRY(fixup_pv_table) 590 stmfd sp!, {r4 - r7, lr} 591 ldr r2, 2f @ get address of __pv_phys_offset 592 mov r3, #0 @ no offset 593 mov r4, r0 @ r0 = table start 594 add r5, r0, r1 @ r1 = table size 595 ldr r6, [r2, #4] @ get __pv_offset 596 bl __fixup_a_pv_table 597 ldmfd sp!, {r4 - r7, pc} 598ENDPROC(fixup_pv_table) 599 600 .align 6012: .long __pv_phys_offset 602 603 .data 604 .globl __pv_phys_offset 605 .type __pv_phys_offset, %object 606__pv_phys_offset: 607 .long 0 608 .size __pv_phys_offset, . - __pv_phys_offset 609__pv_offset: 610 .long 0 611#endif 612 613#include "head-common.S" 614