1/* SPDX-License-Identifier: GPL-2.0-or-later */ 2/* 3 * OpenRISC entry.S 4 * 5 * Linux architectural port borrowing liberally from similar works of 6 * others. All original copyrights apply as per the original source 7 * declaration. 8 * 9 * Modifications for the OpenRISC architecture: 10 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> 11 * Copyright (C) 2005 Gyorgy Jeney <nog@bsemi.com> 12 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> 13 */ 14 15#include <linux/linkage.h> 16#include <linux/pgtable.h> 17 18#include <asm/processor.h> 19#include <asm/unistd.h> 20#include <asm/thread_info.h> 21#include <asm/errno.h> 22#include <asm/spr_defs.h> 23#include <asm/page.h> 24#include <asm/mmu.h> 25#include <asm/asm-offsets.h> 26 27#define DISABLE_INTERRUPTS(t1,t2) \ 28 l.mfspr t2,r0,SPR_SR ;\ 29 l.movhi t1,hi(~(SPR_SR_IEE|SPR_SR_TEE)) ;\ 30 l.ori t1,t1,lo(~(SPR_SR_IEE|SPR_SR_TEE)) ;\ 31 l.and t2,t2,t1 ;\ 32 l.mtspr r0,t2,SPR_SR 33 34#define ENABLE_INTERRUPTS(t1) \ 35 l.mfspr t1,r0,SPR_SR ;\ 36 l.ori t1,t1,lo(SPR_SR_IEE|SPR_SR_TEE) ;\ 37 l.mtspr r0,t1,SPR_SR 38 39/* =========================================================[ macros ]=== */ 40 41#ifdef CONFIG_TRACE_IRQFLAGS 42/* 43 * Trace irq on/off creating a stack frame. 44 */ 45#define TRACE_IRQS_OP(trace_op) \ 46 l.sw -8(r1),r2 /* store frame pointer */ ;\ 47 l.sw -4(r1),r9 /* store return address */ ;\ 48 l.addi r2,r1,0 /* move sp to fp */ ;\ 49 l.jal trace_op ;\ 50 l.addi r1,r1,-8 ;\ 51 l.ori r1,r2,0 /* restore sp */ ;\ 52 l.lwz r9,-4(r1) /* restore return address */ ;\ 53 l.lwz r2,-8(r1) /* restore fp */ ;\ 54/* 55 * Trace irq on/off and save registers we need that would otherwise be 56 * clobbered. 57 */ 58#define TRACE_IRQS_SAVE(t1,trace_op) \ 59 l.sw -12(r1),t1 /* save extra reg */ ;\ 60 l.sw -8(r1),r2 /* store frame pointer */ ;\ 61 l.sw -4(r1),r9 /* store return address */ ;\ 62 l.addi r2,r1,0 /* move sp to fp */ ;\ 63 l.jal trace_op ;\ 64 l.addi r1,r1,-12 ;\ 65 l.ori r1,r2,0 /* restore sp */ ;\ 66 l.lwz r9,-4(r1) /* restore return address */ ;\ 67 l.lwz r2,-8(r1) /* restore fp */ ;\ 68 l.lwz t1,-12(r1) /* restore extra reg */ 69 70#define TRACE_IRQS_OFF TRACE_IRQS_OP(trace_hardirqs_off) 71#define TRACE_IRQS_ON TRACE_IRQS_OP(trace_hardirqs_on) 72#define TRACE_IRQS_ON_SYSCALL \ 73 TRACE_IRQS_SAVE(r10,trace_hardirqs_on) ;\ 74 l.lwz r3,PT_GPR3(r1) ;\ 75 l.lwz r4,PT_GPR4(r1) ;\ 76 l.lwz r5,PT_GPR5(r1) ;\ 77 l.lwz r6,PT_GPR6(r1) ;\ 78 l.lwz r7,PT_GPR7(r1) ;\ 79 l.lwz r8,PT_GPR8(r1) ;\ 80 l.lwz r11,PT_GPR11(r1) 81#define TRACE_IRQS_OFF_ENTRY \ 82 l.lwz r5,PT_SR(r1) ;\ 83 l.andi r3,r5,(SPR_SR_IEE|SPR_SR_TEE) ;\ 84 l.sfeq r5,r0 /* skip trace if irqs were already off */;\ 85 l.bf 1f ;\ 86 l.nop ;\ 87 TRACE_IRQS_SAVE(r4,trace_hardirqs_off) ;\ 881: 89#else 90#define TRACE_IRQS_OFF 91#define TRACE_IRQS_ON 92#define TRACE_IRQS_OFF_ENTRY 93#define TRACE_IRQS_ON_SYSCALL 94#endif 95 96/* 97 * We need to disable interrupts at beginning of RESTORE_ALL 98 * since interrupt might come in after we've loaded EPC return address 99 * and overwrite EPC with address somewhere in RESTORE_ALL 100 * which is of course wrong! 101 */ 102 103#define RESTORE_ALL \ 104 DISABLE_INTERRUPTS(r3,r4) ;\ 105 l.lwz r3,PT_PC(r1) ;\ 106 l.mtspr r0,r3,SPR_EPCR_BASE ;\ 107 l.lwz r3,PT_SR(r1) ;\ 108 l.mtspr r0,r3,SPR_ESR_BASE ;\ 109 l.lwz r2,PT_GPR2(r1) ;\ 110 l.lwz r3,PT_GPR3(r1) ;\ 111 l.lwz r4,PT_GPR4(r1) ;\ 112 l.lwz r5,PT_GPR5(r1) ;\ 113 l.lwz r6,PT_GPR6(r1) ;\ 114 l.lwz r7,PT_GPR7(r1) ;\ 115 l.lwz r8,PT_GPR8(r1) ;\ 116 l.lwz r9,PT_GPR9(r1) ;\ 117 l.lwz r10,PT_GPR10(r1) ;\ 118 l.lwz r11,PT_GPR11(r1) ;\ 119 l.lwz r12,PT_GPR12(r1) ;\ 120 l.lwz r13,PT_GPR13(r1) ;\ 121 l.lwz r14,PT_GPR14(r1) ;\ 122 l.lwz r15,PT_GPR15(r1) ;\ 123 l.lwz r16,PT_GPR16(r1) ;\ 124 l.lwz r17,PT_GPR17(r1) ;\ 125 l.lwz r18,PT_GPR18(r1) ;\ 126 l.lwz r19,PT_GPR19(r1) ;\ 127 l.lwz r20,PT_GPR20(r1) ;\ 128 l.lwz r21,PT_GPR21(r1) ;\ 129 l.lwz r22,PT_GPR22(r1) ;\ 130 l.lwz r23,PT_GPR23(r1) ;\ 131 l.lwz r24,PT_GPR24(r1) ;\ 132 l.lwz r25,PT_GPR25(r1) ;\ 133 l.lwz r26,PT_GPR26(r1) ;\ 134 l.lwz r27,PT_GPR27(r1) ;\ 135 l.lwz r28,PT_GPR28(r1) ;\ 136 l.lwz r29,PT_GPR29(r1) ;\ 137 l.lwz r30,PT_GPR30(r1) ;\ 138 l.lwz r31,PT_GPR31(r1) ;\ 139 l.lwz r1,PT_SP(r1) ;\ 140 l.rfe 141 142 143#define EXCEPTION_ENTRY(handler) \ 144 .global handler ;\ 145handler: ;\ 146 /* r1, EPCR, ESR a already saved */ ;\ 147 l.sw PT_GPR2(r1),r2 ;\ 148 l.sw PT_GPR3(r1),r3 ;\ 149 /* r4 already save */ ;\ 150 l.sw PT_GPR5(r1),r5 ;\ 151 l.sw PT_GPR6(r1),r6 ;\ 152 l.sw PT_GPR7(r1),r7 ;\ 153 l.sw PT_GPR8(r1),r8 ;\ 154 l.sw PT_GPR9(r1),r9 ;\ 155 /* r10 already saved */ ;\ 156 l.sw PT_GPR11(r1),r11 ;\ 157 /* r12 already saved */ ;\ 158 l.sw PT_GPR13(r1),r13 ;\ 159 l.sw PT_GPR14(r1),r14 ;\ 160 l.sw PT_GPR15(r1),r15 ;\ 161 l.sw PT_GPR16(r1),r16 ;\ 162 l.sw PT_GPR17(r1),r17 ;\ 163 l.sw PT_GPR18(r1),r18 ;\ 164 l.sw PT_GPR19(r1),r19 ;\ 165 l.sw PT_GPR20(r1),r20 ;\ 166 l.sw PT_GPR21(r1),r21 ;\ 167 l.sw PT_GPR22(r1),r22 ;\ 168 l.sw PT_GPR23(r1),r23 ;\ 169 l.sw PT_GPR24(r1),r24 ;\ 170 l.sw PT_GPR25(r1),r25 ;\ 171 l.sw PT_GPR26(r1),r26 ;\ 172 l.sw PT_GPR27(r1),r27 ;\ 173 l.sw PT_GPR28(r1),r28 ;\ 174 l.sw PT_GPR29(r1),r29 ;\ 175 /* r30 already save */ ;\ 176/* l.sw PT_GPR30(r1),r30*/ ;\ 177 l.sw PT_GPR31(r1),r31 ;\ 178 TRACE_IRQS_OFF_ENTRY ;\ 179 /* Store -1 in orig_gpr11 for non-syscall exceptions */ ;\ 180 l.addi r30,r0,-1 ;\ 181 l.sw PT_ORIG_GPR11(r1),r30 182 183#define UNHANDLED_EXCEPTION(handler,vector) \ 184 .global handler ;\ 185handler: ;\ 186 /* r1, EPCR, ESR already saved */ ;\ 187 l.sw PT_GPR2(r1),r2 ;\ 188 l.sw PT_GPR3(r1),r3 ;\ 189 l.sw PT_GPR5(r1),r5 ;\ 190 l.sw PT_GPR6(r1),r6 ;\ 191 l.sw PT_GPR7(r1),r7 ;\ 192 l.sw PT_GPR8(r1),r8 ;\ 193 l.sw PT_GPR9(r1),r9 ;\ 194 /* r10 already saved */ ;\ 195 l.sw PT_GPR11(r1),r11 ;\ 196 /* r12 already saved */ ;\ 197 l.sw PT_GPR13(r1),r13 ;\ 198 l.sw PT_GPR14(r1),r14 ;\ 199 l.sw PT_GPR15(r1),r15 ;\ 200 l.sw PT_GPR16(r1),r16 ;\ 201 l.sw PT_GPR17(r1),r17 ;\ 202 l.sw PT_GPR18(r1),r18 ;\ 203 l.sw PT_GPR19(r1),r19 ;\ 204 l.sw PT_GPR20(r1),r20 ;\ 205 l.sw PT_GPR21(r1),r21 ;\ 206 l.sw PT_GPR22(r1),r22 ;\ 207 l.sw PT_GPR23(r1),r23 ;\ 208 l.sw PT_GPR24(r1),r24 ;\ 209 l.sw PT_GPR25(r1),r25 ;\ 210 l.sw PT_GPR26(r1),r26 ;\ 211 l.sw PT_GPR27(r1),r27 ;\ 212 l.sw PT_GPR28(r1),r28 ;\ 213 l.sw PT_GPR29(r1),r29 ;\ 214 /* r31 already saved */ ;\ 215 l.sw PT_GPR30(r1),r30 ;\ 216/* l.sw PT_GPR31(r1),r31 */ ;\ 217 /* Store -1 in orig_gpr11 for non-syscall exceptions */ ;\ 218 l.addi r30,r0,-1 ;\ 219 l.sw PT_ORIG_GPR11(r1),r30 ;\ 220 l.addi r3,r1,0 ;\ 221 /* r4 is exception EA */ ;\ 222 l.addi r5,r0,vector ;\ 223 l.jal unhandled_exception ;\ 224 l.nop ;\ 225 l.j _ret_from_exception ;\ 226 l.nop 227 228/* clobbers 'reg' */ 229#define CLEAR_LWA_FLAG(reg) \ 230 l.movhi reg,hi(lwa_flag) ;\ 231 l.ori reg,reg,lo(lwa_flag) ;\ 232 l.sw 0(reg),r0 233/* 234 * NOTE: one should never assume that SPR_EPC, SPR_ESR, SPR_EEAR 235 * contain the same values as when exception we're handling 236 * occured. in fact they never do. if you need them use 237 * values saved on stack (for SPR_EPC, SPR_ESR) or content 238 * of r4 (for SPR_EEAR). for details look at EXCEPTION_HANDLE() 239 * in 'arch/openrisc/kernel/head.S' 240 */ 241 242/* =====================================================[ exceptions] === */ 243 244/* ---[ 0x100: RESET exception ]----------------------------------------- */ 245 246EXCEPTION_ENTRY(_tng_kernel_start) 247 l.jal _start 248 l.andi r0,r0,0 249 250/* ---[ 0x200: BUS exception ]------------------------------------------- */ 251 252EXCEPTION_ENTRY(_bus_fault_handler) 253 CLEAR_LWA_FLAG(r3) 254 /* r4: EA of fault (set by EXCEPTION_HANDLE) */ 255 l.jal do_bus_fault 256 l.addi r3,r1,0 /* pt_regs */ 257 258 l.j _ret_from_exception 259 l.nop 260 261/* ---[ 0x300: Data Page Fault exception ]------------------------------- */ 262EXCEPTION_ENTRY(_dtlb_miss_page_fault_handler) 263 CLEAR_LWA_FLAG(r3) 264 l.and r5,r5,r0 265 l.j 1f 266 l.nop 267 268EXCEPTION_ENTRY(_data_page_fault_handler) 269 CLEAR_LWA_FLAG(r3) 270 /* set up parameters for do_page_fault */ 271 l.ori r5,r0,0x300 // exception vector 2721: 273 l.addi r3,r1,0 // pt_regs 274 /* r4 set be EXCEPTION_HANDLE */ // effective address of fault 275 276#ifdef CONFIG_OPENRISC_NO_SPR_SR_DSX 277 l.lwz r6,PT_PC(r3) // address of an offending insn 278 l.lwz r6,0(r6) // instruction that caused pf 279 280 l.srli r6,r6,26 // check opcode for jump insn 281 l.sfeqi r6,0 // l.j 282 l.bf 8f 283 l.sfeqi r6,1 // l.jal 284 l.bf 8f 285 l.sfeqi r6,3 // l.bnf 286 l.bf 8f 287 l.sfeqi r6,4 // l.bf 288 l.bf 8f 289 l.sfeqi r6,0x11 // l.jr 290 l.bf 8f 291 l.sfeqi r6,0x12 // l.jalr 292 l.bf 8f 293 l.nop 294 295 l.j 9f 296 l.nop 297 2988: // offending insn is in delay slot 299 l.lwz r6,PT_PC(r3) // address of an offending insn 300 l.addi r6,r6,4 301 l.lwz r6,0(r6) // instruction that caused pf 302 l.srli r6,r6,26 // get opcode 3039: // offending instruction opcode loaded in r6 304 305#else 306 307 l.mfspr r6,r0,SPR_SR // SR 308 l.andi r6,r6,SPR_SR_DSX // check for delay slot exception 309 l.sfne r6,r0 // exception happened in delay slot 310 l.bnf 7f 311 l.lwz r6,PT_PC(r3) // address of an offending insn 312 313 l.addi r6,r6,4 // offending insn is in delay slot 3147: 315 l.lwz r6,0(r6) // instruction that caused pf 316 l.srli r6,r6,26 // check opcode for write access 317#endif 318 319 l.sfgeui r6,0x33 // check opcode for write access 320 l.bnf 1f 321 l.sfleui r6,0x37 322 l.bnf 1f 323 l.ori r6,r0,0x1 // write access 324 l.j 2f 325 l.nop 3261: l.ori r6,r0,0x0 // !write access 3272: 328 329 /* call fault.c handler in openrisc/mm/fault.c */ 330 l.jal do_page_fault 331 l.nop 332 l.j _ret_from_exception 333 l.nop 334 335/* ---[ 0x400: Insn Page Fault exception ]------------------------------- */ 336EXCEPTION_ENTRY(_itlb_miss_page_fault_handler) 337 CLEAR_LWA_FLAG(r3) 338 l.and r5,r5,r0 339 l.j 1f 340 l.nop 341 342EXCEPTION_ENTRY(_insn_page_fault_handler) 343 CLEAR_LWA_FLAG(r3) 344 /* set up parameters for do_page_fault */ 345 l.ori r5,r0,0x400 // exception vector 3461: 347 l.addi r3,r1,0 // pt_regs 348 /* r4 set be EXCEPTION_HANDLE */ // effective address of fault 349 l.ori r6,r0,0x0 // !write access 350 351 /* call fault.c handler in openrisc/mm/fault.c */ 352 l.jal do_page_fault 353 l.nop 354 l.j _ret_from_exception 355 l.nop 356 357 358/* ---[ 0x500: Timer exception ]----------------------------------------- */ 359 360EXCEPTION_ENTRY(_timer_handler) 361 CLEAR_LWA_FLAG(r3) 362 l.jal timer_interrupt 363 l.addi r3,r1,0 /* pt_regs */ 364 365 l.j _ret_from_intr 366 l.nop 367 368/* ---[ 0x600: Alignment exception ]-------------------------------------- */ 369 370EXCEPTION_ENTRY(_alignment_handler) 371 CLEAR_LWA_FLAG(r3) 372 /* r4: EA of fault (set by EXCEPTION_HANDLE) */ 373 l.jal do_unaligned_access 374 l.addi r3,r1,0 /* pt_regs */ 375 376 l.j _ret_from_exception 377 l.nop 378 379#if 0 380EXCEPTION_ENTRY(_alignment_handler) 381// l.mfspr r2,r0,SPR_EEAR_BASE /* Load the effective address */ 382 l.addi r2,r4,0 383// l.mfspr r5,r0,SPR_EPCR_BASE /* Load the insn address */ 384 l.lwz r5,PT_PC(r1) 385 386 l.lwz r3,0(r5) /* Load insn */ 387 l.srli r4,r3,26 /* Shift left to get the insn opcode */ 388 389 l.sfeqi r4,0x00 /* Check if the load/store insn is in delay slot */ 390 l.bf jmp 391 l.sfeqi r4,0x01 392 l.bf jmp 393 l.sfeqi r4,0x03 394 l.bf jmp 395 l.sfeqi r4,0x04 396 l.bf jmp 397 l.sfeqi r4,0x11 398 l.bf jr 399 l.sfeqi r4,0x12 400 l.bf jr 401 l.nop 402 l.j 1f 403 l.addi r5,r5,4 /* Increment PC to get return insn address */ 404 405jmp: 406 l.slli r4,r3,6 /* Get the signed extended jump length */ 407 l.srai r4,r4,4 408 409 l.lwz r3,4(r5) /* Load the real load/store insn */ 410 411 l.add r5,r5,r4 /* Calculate jump target address */ 412 413 l.j 1f 414 l.srli r4,r3,26 /* Shift left to get the insn opcode */ 415 416jr: 417 l.slli r4,r3,9 /* Shift to get the reg nb */ 418 l.andi r4,r4,0x7c 419 420 l.lwz r3,4(r5) /* Load the real load/store insn */ 421 422 l.add r4,r4,r1 /* Load the jump register value from the stack */ 423 l.lwz r5,0(r4) 424 425 l.srli r4,r3,26 /* Shift left to get the insn opcode */ 426 427 4281: 429// l.mtspr r0,r5,SPR_EPCR_BASE 430 l.sw PT_PC(r1),r5 431 432 l.sfeqi r4,0x26 433 l.bf lhs 434 l.sfeqi r4,0x25 435 l.bf lhz 436 l.sfeqi r4,0x22 437 l.bf lws 438 l.sfeqi r4,0x21 439 l.bf lwz 440 l.sfeqi r4,0x37 441 l.bf sh 442 l.sfeqi r4,0x35 443 l.bf sw 444 l.nop 445 4461: l.j 1b /* I don't know what to do */ 447 l.nop 448 449lhs: l.lbs r5,0(r2) 450 l.slli r5,r5,8 451 l.lbz r6,1(r2) 452 l.or r5,r5,r6 453 l.srli r4,r3,19 454 l.andi r4,r4,0x7c 455 l.add r4,r4,r1 456 l.j align_end 457 l.sw 0(r4),r5 458 459lhz: l.lbz r5,0(r2) 460 l.slli r5,r5,8 461 l.lbz r6,1(r2) 462 l.or r5,r5,r6 463 l.srli r4,r3,19 464 l.andi r4,r4,0x7c 465 l.add r4,r4,r1 466 l.j align_end 467 l.sw 0(r4),r5 468 469lws: l.lbs r5,0(r2) 470 l.slli r5,r5,24 471 l.lbz r6,1(r2) 472 l.slli r6,r6,16 473 l.or r5,r5,r6 474 l.lbz r6,2(r2) 475 l.slli r6,r6,8 476 l.or r5,r5,r6 477 l.lbz r6,3(r2) 478 l.or r5,r5,r6 479 l.srli r4,r3,19 480 l.andi r4,r4,0x7c 481 l.add r4,r4,r1 482 l.j align_end 483 l.sw 0(r4),r5 484 485lwz: l.lbz r5,0(r2) 486 l.slli r5,r5,24 487 l.lbz r6,1(r2) 488 l.slli r6,r6,16 489 l.or r5,r5,r6 490 l.lbz r6,2(r2) 491 l.slli r6,r6,8 492 l.or r5,r5,r6 493 l.lbz r6,3(r2) 494 l.or r5,r5,r6 495 l.srli r4,r3,19 496 l.andi r4,r4,0x7c 497 l.add r4,r4,r1 498 l.j align_end 499 l.sw 0(r4),r5 500 501sh: 502 l.srli r4,r3,9 503 l.andi r4,r4,0x7c 504 l.add r4,r4,r1 505 l.lwz r5,0(r4) 506 l.sb 1(r2),r5 507 l.srli r5,r5,8 508 l.j align_end 509 l.sb 0(r2),r5 510 511sw: 512 l.srli r4,r3,9 513 l.andi r4,r4,0x7c 514 l.add r4,r4,r1 515 l.lwz r5,0(r4) 516 l.sb 3(r2),r5 517 l.srli r5,r5,8 518 l.sb 2(r2),r5 519 l.srli r5,r5,8 520 l.sb 1(r2),r5 521 l.srli r5,r5,8 522 l.j align_end 523 l.sb 0(r2),r5 524 525align_end: 526 l.j _ret_from_intr 527 l.nop 528#endif 529 530/* ---[ 0x700: Illegal insn exception ]---------------------------------- */ 531 532EXCEPTION_ENTRY(_illegal_instruction_handler) 533 /* r4: EA of fault (set by EXCEPTION_HANDLE) */ 534 l.jal do_illegal_instruction 535 l.addi r3,r1,0 /* pt_regs */ 536 537 l.j _ret_from_exception 538 l.nop 539 540/* ---[ 0x800: External interrupt exception ]---------------------------- */ 541 542EXCEPTION_ENTRY(_external_irq_handler) 543#ifdef CONFIG_OPENRISC_ESR_EXCEPTION_BUG_CHECK 544 l.lwz r4,PT_SR(r1) // were interrupts enabled ? 545 l.andi r4,r4,SPR_SR_IEE 546 l.sfeqi r4,0 547 l.bnf 1f // ext irq enabled, all ok. 548 l.nop 549 550#ifdef CONFIG_PRINTK 551 l.addi r1,r1,-0x8 552 l.movhi r3,hi(42f) 553 l.ori r3,r3,lo(42f) 554 l.sw 0x0(r1),r3 555 l.jal _printk 556 l.sw 0x4(r1),r4 557 l.addi r1,r1,0x8 558 559 .section .rodata, "a" 56042: 561 .string "\n\rESR interrupt bug: in _external_irq_handler (ESR %x)\n\r" 562 .align 4 563 .previous 564#endif 565 566 l.ori r4,r4,SPR_SR_IEE // fix the bug 567// l.sw PT_SR(r1),r4 5681: 569#endif 570 CLEAR_LWA_FLAG(r3) 571 l.addi r3,r1,0 572 l.movhi r8,hi(generic_handle_arch_irq) 573 l.ori r8,r8,lo(generic_handle_arch_irq) 574 l.jalr r8 575 l.nop 576 l.j _ret_from_intr 577 l.nop 578 579/* ---[ 0x900: DTLB miss exception ]------------------------------------- */ 580 581 582/* ---[ 0xa00: ITLB miss exception ]------------------------------------- */ 583 584 585/* ---[ 0xb00: Range exception ]----------------------------------------- */ 586 587UNHANDLED_EXCEPTION(_vector_0xb00,0xb00) 588 589/* ---[ 0xc00: Syscall exception ]--------------------------------------- */ 590 591/* 592 * Syscalls are a special type of exception in that they are 593 * _explicitly_ invoked by userspace and can therefore be 594 * held to conform to the same ABI as normal functions with 595 * respect to whether registers are preserved across the call 596 * or not. 597 */ 598 599/* Upon syscall entry we just save the callee-saved registers 600 * and not the call-clobbered ones. 601 */ 602 603_string_syscall_return: 604 .string "syscall return %ld \n\r\0" 605 .align 4 606 607ENTRY(_sys_call_handler) 608 /* r1, EPCR, ESR a already saved */ 609 l.sw PT_GPR2(r1),r2 610 /* r3-r8 must be saved because syscall restart relies 611 * on us being able to restart the syscall args... technically 612 * they should be clobbered, otherwise 613 */ 614 l.sw PT_GPR3(r1),r3 615 /* 616 * r4 already saved 617 * r4 holds the EEAR address of the fault, use it as screatch reg and 618 * then load the original r4 619 */ 620 CLEAR_LWA_FLAG(r4) 621 l.lwz r4,PT_GPR4(r1) 622 l.sw PT_GPR5(r1),r5 623 l.sw PT_GPR6(r1),r6 624 l.sw PT_GPR7(r1),r7 625 l.sw PT_GPR8(r1),r8 626 l.sw PT_GPR9(r1),r9 627 /* r10 already saved */ 628 l.sw PT_GPR11(r1),r11 629 /* orig_gpr11 must be set for syscalls */ 630 l.sw PT_ORIG_GPR11(r1),r11 631 /* r12,r13 already saved */ 632 633 /* r14-r28 (even) aren't touched by the syscall fast path below 634 * so we don't need to save them. However, the functions that return 635 * to userspace via a call to switch() DO need to save these because 636 * switch() effectively clobbers them... saving these registers for 637 * such functions is handled in their syscall wrappers (see fork, vfork, 638 * and clone, below). 639 640 /* r30 is the only register we clobber in the fast path */ 641 /* r30 already saved */ 642/* l.sw PT_GPR30(r1),r30 */ 643 644_syscall_check_trace_enter: 645 /* syscalls run with interrupts enabled */ 646 TRACE_IRQS_ON_SYSCALL 647 ENABLE_INTERRUPTS(r29) // enable interrupts, r29 is temp 648 649 /* If TIF_SYSCALL_TRACE is set, then we want to do syscall tracing */ 650 l.lwz r30,TI_FLAGS(r10) 651 l.andi r30,r30,_TIF_SYSCALL_TRACE 652 l.sfne r30,r0 653 l.bf _syscall_trace_enter 654 l.nop 655 656_syscall_check: 657 /* Ensure that the syscall number is reasonable */ 658 l.sfgeui r11,__NR_syscalls 659 l.bf _syscall_badsys 660 l.nop 661 662_syscall_call: 663 l.movhi r29,hi(sys_call_table) 664 l.ori r29,r29,lo(sys_call_table) 665 l.slli r11,r11,2 666 l.add r29,r29,r11 667 l.lwz r29,0(r29) 668 669 l.jalr r29 670 l.nop 671 672_syscall_return: 673 /* All syscalls return here... just pay attention to ret_from_fork 674 * which does it in a round-about way. 675 */ 676 l.sw PT_GPR11(r1),r11 // save return value 677 678#if 0 679_syscall_debug: 680 l.movhi r3,hi(_string_syscall_return) 681 l.ori r3,r3,lo(_string_syscall_return) 682 l.ori r27,r0,1 683 l.sw -4(r1),r27 684 l.sw -8(r1),r11 685 l.addi r1,r1,-8 686 l.movhi r27,hi(_printk) 687 l.ori r27,r27,lo(_printk) 688 l.jalr r27 689 l.nop 690 l.addi r1,r1,8 691#endif 692 693_syscall_check_trace_leave: 694 /* r30 is a callee-saved register so this should still hold the 695 * _TIF_SYSCALL_TRACE flag from _syscall_check_trace_enter above... 696 * _syscall_trace_leave expects syscall result to be in pt_regs->r11. 697 */ 698 l.sfne r30,r0 699 l.bf _syscall_trace_leave 700 l.nop 701 702/* This is where the exception-return code begins... interrupts need to be 703 * disabled the rest of the way here because we can't afford to miss any 704 * interrupts that set NEED_RESCHED or SIGNALPENDING... really true? */ 705 706_syscall_check_work: 707 /* Here we need to disable interrupts */ 708 DISABLE_INTERRUPTS(r27,r29) 709 TRACE_IRQS_OFF 710 l.lwz r30,TI_FLAGS(r10) 711 l.andi r30,r30,_TIF_WORK_MASK 712 l.sfne r30,r0 713 714 l.bnf _syscall_resume_userspace 715 l.nop 716 717 /* Work pending follows a different return path, so we need to 718 * make sure that all the call-saved registers get into pt_regs 719 * before branching... 720 */ 721 l.sw PT_GPR14(r1),r14 722 l.sw PT_GPR16(r1),r16 723 l.sw PT_GPR18(r1),r18 724 l.sw PT_GPR20(r1),r20 725 l.sw PT_GPR22(r1),r22 726 l.sw PT_GPR24(r1),r24 727 l.sw PT_GPR26(r1),r26 728 l.sw PT_GPR28(r1),r28 729 730 /* _work_pending needs to be called with interrupts disabled */ 731 l.j _work_pending 732 l.nop 733 734_syscall_resume_userspace: 735// ENABLE_INTERRUPTS(r29) 736 737 738/* This is the hot path for returning to userspace from a syscall. If there's 739 * work to be done and the branch to _work_pending was taken above, then the 740 * return to userspace will be done via the normal exception return path... 741 * that path restores _all_ registers and will overwrite the "clobbered" 742 * registers with whatever garbage is in pt_regs -- that's OK because those 743 * registers are clobbered anyway and because the extra work is insignificant 744 * in the context of the extra work that _work_pending is doing. 745 746/* Once again, syscalls are special and only guarantee to preserve the 747 * same registers as a normal function call */ 748 749/* The assumption here is that the registers r14-r28 (even) are untouched and 750 * don't need to be restored... be sure that that's really the case! 751 */ 752 753/* This is still too much... we should only be restoring what we actually 754 * clobbered... we should even be using 'scratch' (odd) regs above so that 755 * we don't need to restore anything, hardly... 756 */ 757 758 l.lwz r2,PT_GPR2(r1) 759 760 /* Restore args */ 761 /* r3-r8 are technically clobbered, but syscall restart needs these 762 * to be restored... 763 */ 764 l.lwz r3,PT_GPR3(r1) 765 l.lwz r4,PT_GPR4(r1) 766 l.lwz r5,PT_GPR5(r1) 767 l.lwz r6,PT_GPR6(r1) 768 l.lwz r7,PT_GPR7(r1) 769 l.lwz r8,PT_GPR8(r1) 770 771 l.lwz r9,PT_GPR9(r1) 772 l.lwz r10,PT_GPR10(r1) 773 l.lwz r11,PT_GPR11(r1) 774 775 /* r30 is the only register we clobber in the fast path */ 776 l.lwz r30,PT_GPR30(r1) 777 778 /* Here we use r13-r19 (odd) as scratch regs */ 779 l.lwz r13,PT_PC(r1) 780 l.lwz r15,PT_SR(r1) 781 l.lwz r1,PT_SP(r1) 782 /* Interrupts need to be disabled for setting EPCR and ESR 783 * so that another interrupt doesn't come in here and clobber 784 * them before we can use them for our l.rfe */ 785 DISABLE_INTERRUPTS(r17,r19) 786 l.mtspr r0,r13,SPR_EPCR_BASE 787 l.mtspr r0,r15,SPR_ESR_BASE 788 l.rfe 789 790/* End of hot path! 791 * Keep the below tracing and error handling out of the hot path... 792*/ 793 794_syscall_trace_enter: 795 /* Here we pass pt_regs to do_syscall_trace_enter. Make sure 796 * that function is really getting all the info it needs as 797 * pt_regs isn't a complete set of userspace regs, just the 798 * ones relevant to the syscall... 799 * 800 * Note use of delay slot for setting argument. 801 */ 802 l.jal do_syscall_trace_enter 803 l.addi r3,r1,0 804 805 /* Restore arguments (not preserved across do_syscall_trace_enter) 806 * so that we can do the syscall for real and return to the syscall 807 * hot path. 808 */ 809 l.lwz r11,PT_GPR11(r1) 810 l.lwz r3,PT_GPR3(r1) 811 l.lwz r4,PT_GPR4(r1) 812 l.lwz r5,PT_GPR5(r1) 813 l.lwz r6,PT_GPR6(r1) 814 l.lwz r7,PT_GPR7(r1) 815 816 l.j _syscall_check 817 l.lwz r8,PT_GPR8(r1) 818 819_syscall_trace_leave: 820 l.jal do_syscall_trace_leave 821 l.addi r3,r1,0 822 823 l.j _syscall_check_work 824 l.nop 825 826_syscall_badsys: 827 /* Here we effectively pretend to have executed an imaginary 828 * syscall that returns -ENOSYS and then return to the regular 829 * syscall hot path. 830 * Note that "return value" is set in the delay slot... 831 */ 832 l.j _syscall_return 833 l.addi r11,r0,-ENOSYS 834 835/******* END SYSCALL HANDLING *******/ 836 837/* ---[ 0xd00: Trap exception ]------------------------------------------ */ 838 839UNHANDLED_EXCEPTION(_vector_0xd00,0xd00) 840 841/* ---[ 0xe00: Trap exception ]------------------------------------------ */ 842 843EXCEPTION_ENTRY(_trap_handler) 844 CLEAR_LWA_FLAG(r3) 845 /* r4: EA of fault (set by EXCEPTION_HANDLE) */ 846 l.jal do_trap 847 l.addi r3,r1,0 /* pt_regs */ 848 849 l.j _ret_from_exception 850 l.nop 851 852/* ---[ 0xf00: Reserved exception ]-------------------------------------- */ 853 854UNHANDLED_EXCEPTION(_vector_0xf00,0xf00) 855 856/* ---[ 0x1000: Reserved exception ]------------------------------------- */ 857 858UNHANDLED_EXCEPTION(_vector_0x1000,0x1000) 859 860/* ---[ 0x1100: Reserved exception ]------------------------------------- */ 861 862UNHANDLED_EXCEPTION(_vector_0x1100,0x1100) 863 864/* ---[ 0x1200: Reserved exception ]------------------------------------- */ 865 866UNHANDLED_EXCEPTION(_vector_0x1200,0x1200) 867 868/* ---[ 0x1300: Reserved exception ]------------------------------------- */ 869 870UNHANDLED_EXCEPTION(_vector_0x1300,0x1300) 871 872/* ---[ 0x1400: Reserved exception ]------------------------------------- */ 873 874UNHANDLED_EXCEPTION(_vector_0x1400,0x1400) 875 876/* ---[ 0x1500: Reserved exception ]------------------------------------- */ 877 878UNHANDLED_EXCEPTION(_vector_0x1500,0x1500) 879 880/* ---[ 0x1600: Reserved exception ]------------------------------------- */ 881 882UNHANDLED_EXCEPTION(_vector_0x1600,0x1600) 883 884/* ---[ 0x1700: Reserved exception ]------------------------------------- */ 885 886UNHANDLED_EXCEPTION(_vector_0x1700,0x1700) 887 888/* ---[ 0x1800: Reserved exception ]------------------------------------- */ 889 890UNHANDLED_EXCEPTION(_vector_0x1800,0x1800) 891 892/* ---[ 0x1900: Reserved exception ]------------------------------------- */ 893 894UNHANDLED_EXCEPTION(_vector_0x1900,0x1900) 895 896/* ---[ 0x1a00: Reserved exception ]------------------------------------- */ 897 898UNHANDLED_EXCEPTION(_vector_0x1a00,0x1a00) 899 900/* ---[ 0x1b00: Reserved exception ]------------------------------------- */ 901 902UNHANDLED_EXCEPTION(_vector_0x1b00,0x1b00) 903 904/* ---[ 0x1c00: Reserved exception ]------------------------------------- */ 905 906UNHANDLED_EXCEPTION(_vector_0x1c00,0x1c00) 907 908/* ---[ 0x1d00: Reserved exception ]------------------------------------- */ 909 910UNHANDLED_EXCEPTION(_vector_0x1d00,0x1d00) 911 912/* ---[ 0x1e00: Reserved exception ]------------------------------------- */ 913 914UNHANDLED_EXCEPTION(_vector_0x1e00,0x1e00) 915 916/* ---[ 0x1f00: Reserved exception ]------------------------------------- */ 917 918UNHANDLED_EXCEPTION(_vector_0x1f00,0x1f00) 919 920/* ========================================================[ return ] === */ 921 922_resume_userspace: 923 DISABLE_INTERRUPTS(r3,r4) 924 TRACE_IRQS_OFF 925 l.lwz r4,TI_FLAGS(r10) 926 l.andi r13,r4,_TIF_WORK_MASK 927 l.sfeqi r13,0 928 l.bf _restore_all 929 l.nop 930 931_work_pending: 932 l.lwz r5,PT_ORIG_GPR11(r1) 933 l.sfltsi r5,0 934 l.bnf 1f 935 l.nop 936 l.andi r5,r5,0 9371: 938 l.jal do_work_pending 939 l.ori r3,r1,0 /* pt_regs */ 940 941 l.sfeqi r11,0 942 l.bf _restore_all 943 l.nop 944 l.sfltsi r11,0 945 l.bnf 1f 946 l.nop 947 l.and r11,r11,r0 948 l.ori r11,r11,__NR_restart_syscall 949 l.j _syscall_check_trace_enter 950 l.nop 9511: 952 l.lwz r11,PT_ORIG_GPR11(r1) 953 /* Restore arg registers */ 954 l.lwz r3,PT_GPR3(r1) 955 l.lwz r4,PT_GPR4(r1) 956 l.lwz r5,PT_GPR5(r1) 957 l.lwz r6,PT_GPR6(r1) 958 l.lwz r7,PT_GPR7(r1) 959 l.j _syscall_check_trace_enter 960 l.lwz r8,PT_GPR8(r1) 961 962_restore_all: 963#ifdef CONFIG_TRACE_IRQFLAGS 964 l.lwz r4,PT_SR(r1) 965 l.andi r3,r4,(SPR_SR_IEE|SPR_SR_TEE) 966 l.sfeq r3,r0 /* skip trace if irqs were off */ 967 l.bf skip_hardirqs_on 968 l.nop 969 TRACE_IRQS_ON 970skip_hardirqs_on: 971#endif 972 RESTORE_ALL 973 /* This returns to userspace code */ 974 975 976ENTRY(_ret_from_intr) 977ENTRY(_ret_from_exception) 978 l.lwz r4,PT_SR(r1) 979 l.andi r3,r4,SPR_SR_SM 980 l.sfeqi r3,0 981 l.bnf _restore_all 982 l.nop 983 l.j _resume_userspace 984 l.nop 985 986ENTRY(ret_from_fork) 987 l.jal schedule_tail 988 l.nop 989 990 /* Check if we are a kernel thread */ 991 l.sfeqi r20,0 992 l.bf 1f 993 l.nop 994 995 /* ...we are a kernel thread so invoke the requested callback */ 996 l.jalr r20 997 l.or r3,r22,r0 998 9991: 1000 /* _syscall_returns expect r11 to contain return value */ 1001 l.lwz r11,PT_GPR11(r1) 1002 1003 /* The syscall fast path return expects call-saved registers 1004 * r14-r28 to be untouched, so we restore them here as they 1005 * will have been effectively clobbered when arriving here 1006 * via the call to switch() 1007 */ 1008 l.lwz r14,PT_GPR14(r1) 1009 l.lwz r16,PT_GPR16(r1) 1010 l.lwz r18,PT_GPR18(r1) 1011 l.lwz r20,PT_GPR20(r1) 1012 l.lwz r22,PT_GPR22(r1) 1013 l.lwz r24,PT_GPR24(r1) 1014 l.lwz r26,PT_GPR26(r1) 1015 l.lwz r28,PT_GPR28(r1) 1016 1017 l.j _syscall_return 1018 l.nop 1019 1020/* ========================================================[ switch ] === */ 1021 1022/* 1023 * This routine switches between two different tasks. The process 1024 * state of one is saved on its kernel stack. Then the state 1025 * of the other is restored from its kernel stack. The memory 1026 * management hardware is updated to the second process's state. 1027 * Finally, we can return to the second process, via the 'return'. 1028 * 1029 * Note: there are two ways to get to the "going out" portion 1030 * of this code; either by coming in via the entry (_switch) 1031 * or via "fork" which must set up an environment equivalent 1032 * to the "_switch" path. If you change this (or in particular, the 1033 * SAVE_REGS macro), you'll have to change the fork code also. 1034 */ 1035 1036 1037/* _switch MUST never lay on page boundry, cause it runs from 1038 * effective addresses and beeing interrupted by iTLB miss would kill it. 1039 * dTLB miss seems to never accour in the bad place since data accesses 1040 * are from task structures which are always page aligned. 1041 * 1042 * The problem happens in RESTORE_ALL where we first set the EPCR 1043 * register, then load the previous register values and only at the end call 1044 * the l.rfe instruction. If get TLB miss in beetwen the EPCR register gets 1045 * garbled and we end up calling l.rfe with the wrong EPCR. (same probably 1046 * holds for ESR) 1047 * 1048 * To avoid this problems it is sufficient to align _switch to 1049 * some nice round number smaller than it's size... 1050 */ 1051 1052/* ABI rules apply here... we either enter _switch via schedule() or via 1053 * an imaginary call to which we shall return at return_from_fork. Either 1054 * way, we are a function call and only need to preserve the callee-saved 1055 * registers when we return. As such, we don't need to save the registers 1056 * on the stack that we won't be returning as they were... 1057 */ 1058 1059 .align 0x400 1060ENTRY(_switch) 1061 /* We don't store SR as _switch only gets called in a context where 1062 * the SR will be the same going in and coming out... */ 1063 1064 /* Set up new pt_regs struct for saving task state */ 1065 l.addi r1,r1,-(INT_FRAME_SIZE) 1066 1067 /* No need to store r1/PT_SP as it goes into KSP below */ 1068 l.sw PT_GPR2(r1),r2 1069 l.sw PT_GPR9(r1),r9 1070 1071 /* Save callee-saved registers to the new pt_regs */ 1072 l.sw PT_GPR14(r1),r14 1073 l.sw PT_GPR16(r1),r16 1074 l.sw PT_GPR18(r1),r18 1075 l.sw PT_GPR20(r1),r20 1076 l.sw PT_GPR22(r1),r22 1077 l.sw PT_GPR24(r1),r24 1078 l.sw PT_GPR26(r1),r26 1079 l.sw PT_GPR28(r1),r28 1080 l.sw PT_GPR30(r1),r30 1081 1082 l.addi r11,r10,0 /* Save old 'current' to 'last' return value*/ 1083 1084 /* We use thread_info->ksp for storing the address of the above 1085 * structure so that we can get back to it later... we don't want 1086 * to lose the value of thread_info->ksp, though, so store it as 1087 * pt_regs->sp so that we can easily restore it when we are made 1088 * live again... 1089 */ 1090 1091 /* Save the old value of thread_info->ksp as pt_regs->sp */ 1092 l.lwz r29,TI_KSP(r10) 1093 l.sw PT_SP(r1),r29 1094 1095 /* Swap kernel stack pointers */ 1096 l.sw TI_KSP(r10),r1 /* Save old stack pointer */ 1097 l.or r10,r4,r0 /* Set up new current_thread_info */ 1098 l.lwz r1,TI_KSP(r10) /* Load new stack pointer */ 1099 1100 /* Restore the old value of thread_info->ksp */ 1101 l.lwz r29,PT_SP(r1) 1102 l.sw TI_KSP(r10),r29 1103 1104 /* ...and restore the registers, except r11 because the return value 1105 * has already been set above. 1106 */ 1107 l.lwz r2,PT_GPR2(r1) 1108 l.lwz r9,PT_GPR9(r1) 1109 /* No need to restore r10 */ 1110 /* ...and do not restore r11 */ 1111 1112 /* Restore callee-saved registers */ 1113 l.lwz r14,PT_GPR14(r1) 1114 l.lwz r16,PT_GPR16(r1) 1115 l.lwz r18,PT_GPR18(r1) 1116 l.lwz r20,PT_GPR20(r1) 1117 l.lwz r22,PT_GPR22(r1) 1118 l.lwz r24,PT_GPR24(r1) 1119 l.lwz r26,PT_GPR26(r1) 1120 l.lwz r28,PT_GPR28(r1) 1121 l.lwz r30,PT_GPR30(r1) 1122 1123 /* Unwind stack to pre-switch state */ 1124 l.addi r1,r1,(INT_FRAME_SIZE) 1125 1126 /* Return via the link-register back to where we 'came from', where 1127 * that may be either schedule(), ret_from_fork(), or 1128 * ret_from_kernel_thread(). If we are returning to a new thread, 1129 * we are expected to have set up the arg to schedule_tail already, 1130 * hence we do so here unconditionally: 1131 */ 1132 l.lwz r3,TI_TASK(r3) /* Load 'prev' as schedule_tail arg */ 1133 l.jr r9 1134 l.nop 1135 1136/* ==================================================================== */ 1137 1138/* These all use the delay slot for setting the argument register, so the 1139 * jump is always happening after the l.addi instruction. 1140 * 1141 * These are all just wrappers that don't touch the link-register r9, so the 1142 * return from the "real" syscall function will return back to the syscall 1143 * code that did the l.jal that brought us here. 1144 */ 1145 1146/* fork requires that we save all the callee-saved registers because they 1147 * are all effectively clobbered by the call to _switch. Here we store 1148 * all the registers that aren't touched by the syscall fast path and thus 1149 * weren't saved there. 1150 */ 1151 1152_fork_save_extra_regs_and_call: 1153 l.sw PT_GPR14(r1),r14 1154 l.sw PT_GPR16(r1),r16 1155 l.sw PT_GPR18(r1),r18 1156 l.sw PT_GPR20(r1),r20 1157 l.sw PT_GPR22(r1),r22 1158 l.sw PT_GPR24(r1),r24 1159 l.sw PT_GPR26(r1),r26 1160 l.jr r29 1161 l.sw PT_GPR28(r1),r28 1162 1163ENTRY(__sys_clone) 1164 l.movhi r29,hi(sys_clone) 1165 l.j _fork_save_extra_regs_and_call 1166 l.ori r29,r29,lo(sys_clone) 1167 1168ENTRY(__sys_clone3) 1169 l.movhi r29,hi(sys_clone3) 1170 l.j _fork_save_extra_regs_and_call 1171 l.ori r29,r29,lo(sys_clone3) 1172 1173ENTRY(__sys_fork) 1174 l.movhi r29,hi(sys_fork) 1175 l.j _fork_save_extra_regs_and_call 1176 l.ori r29,r29,lo(sys_fork) 1177 1178ENTRY(sys_rt_sigreturn) 1179 l.jal _sys_rt_sigreturn 1180 l.addi r3,r1,0 1181 l.sfne r30,r0 1182 l.bnf _no_syscall_trace 1183 l.nop 1184 l.jal do_syscall_trace_leave 1185 l.addi r3,r1,0 1186_no_syscall_trace: 1187 l.j _resume_userspace 1188 l.nop 1189 1190/* This is a catch-all syscall for atomic instructions for the OpenRISC 1000. 1191 * The functions takes a variable number of parameters depending on which 1192 * particular flavour of atomic you want... parameter 1 is a flag identifying 1193 * the atomic in question. Currently, this function implements the 1194 * following variants: 1195 * 1196 * XCHG: 1197 * @flag: 1 1198 * @ptr1: 1199 * @ptr2: 1200 * Atomically exchange the values in pointers 1 and 2. 1201 * 1202 */ 1203 1204ENTRY(sys_or1k_atomic) 1205 /* FIXME: This ignores r3 and always does an XCHG */ 1206 DISABLE_INTERRUPTS(r17,r19) 1207 l.lwz r29,0(r4) 1208 l.lwz r27,0(r5) 1209 l.sw 0(r4),r27 1210 l.sw 0(r5),r29 1211 ENABLE_INTERRUPTS(r17) 1212 l.jr r9 1213 l.or r11,r0,r0 1214 1215/* ============================================================[ EOF ]=== */ 1216