1/* 2 * linux/arch/nios2/kernel/entry.S 3 * 4 * Copyright (C) 2013-2014 Altera Corporation 5 * Copyright (C) 2009, Wind River Systems Inc 6 * 7 * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com 8 * 9 * Copyright (C) 1999-2002, Greg Ungerer (gerg@snapgear.com) 10 * Copyright (C) 1998 D. Jeff Dionne <jeff@lineo.ca>, 11 * Kenneth Albanowski <kjahds@kjahds.com>, 12 * Copyright (C) 2000 Lineo Inc. (www.lineo.com) 13 * Copyright (C) 2004 Microtronix Datacom Ltd. 14 * 15 * This file is subject to the terms and conditions of the GNU General Public 16 * License. See the file "COPYING" in the main directory of this archive 17 * for more details. 18 * 19 * Linux/m68k support by Hamish Macdonald 20 * 21 * 68060 fixes by Jesper Skov 22 * ColdFire support by Greg Ungerer (gerg@snapgear.com) 23 * 5307 fixes by David W. Miller 24 * linux 2.4 support David McCullough <davidm@snapgear.com> 25 */ 26 27#include <linux/sys.h> 28#include <linux/linkage.h> 29#include <asm/asm-offsets.h> 30#include <asm/asm-macros.h> 31#include <asm/thread_info.h> 32#include <asm/errno.h> 33#include <asm/setup.h> 34#include <asm/entry.h> 35#include <asm/unistd.h> 36#include <asm/processor.h> 37 38.macro GET_THREAD_INFO reg 39.if THREAD_SIZE & 0xffff0000 40 andhi \reg, sp, %hi(~(THREAD_SIZE-1)) 41.else 42 addi \reg, r0, %lo(~(THREAD_SIZE-1)) 43 and \reg, \reg, sp 44.endif 45.endm 46 47.macro kuser_cmpxchg_check 48 /* 49 * Make sure our user space atomic helper is restarted if it was 50 * interrupted in a critical region. 51 * ea-4 = address of interrupted insn (ea must be preserved). 52 * sp = saved regs. 53 * cmpxchg_ldw = first critical insn, cmpxchg_stw = last critical insn. 54 * If ea <= cmpxchg_stw and ea > cmpxchg_ldw then saved EA is set to 55 * cmpxchg_ldw + 4. 56 */ 57 /* et = cmpxchg_stw + 4 */ 58 movui et, (KUSER_BASE + 4 + (cmpxchg_stw - __kuser_helper_start)) 59 bgtu ea, et, 1f 60 61 subi et, et, (cmpxchg_stw - cmpxchg_ldw) /* et = cmpxchg_ldw + 4 */ 62 bltu ea, et, 1f 63 stw et, PT_EA(sp) /* fix up EA */ 64 mov ea, et 651: 66.endm 67 68.section .rodata 69.align 4 70exception_table: 71 .word unhandled_exception /* 0 - Reset */ 72 .word unhandled_exception /* 1 - Processor-only Reset */ 73 .word external_interrupt /* 2 - Interrupt */ 74 .word handle_trap /* 3 - Trap Instruction */ 75 76 .word instruction_trap /* 4 - Unimplemented instruction */ 77 .word handle_illegal /* 5 - Illegal instruction */ 78 .word handle_unaligned /* 6 - Misaligned data access */ 79 .word handle_unaligned /* 7 - Misaligned destination address */ 80 81 .word handle_diverror /* 8 - Division error */ 82 .word protection_exception_ba /* 9 - Supervisor-only instr. address */ 83 .word protection_exception_instr /* 10 - Supervisor only instruction */ 84 .word protection_exception_ba /* 11 - Supervisor only data address */ 85 86 .word unhandled_exception /* 12 - Double TLB miss (data) */ 87 .word protection_exception_pte /* 13 - TLB permission violation (x) */ 88 .word protection_exception_pte /* 14 - TLB permission violation (r) */ 89 .word protection_exception_pte /* 15 - TLB permission violation (w) */ 90 91 .word unhandled_exception /* 16 - MPU region violation */ 92 93trap_table: 94 .word handle_system_call /* 0 */ 95 .word handle_trap_1 /* 1 */ 96 .word handle_trap_2 /* 2 */ 97 .word handle_trap_3 /* 3 */ 98 .word handle_trap_reserved /* 4 */ 99 .word handle_trap_reserved /* 5 */ 100 .word handle_trap_reserved /* 6 */ 101 .word handle_trap_reserved /* 7 */ 102 .word handle_trap_reserved /* 8 */ 103 .word handle_trap_reserved /* 9 */ 104 .word handle_trap_reserved /* 10 */ 105 .word handle_trap_reserved /* 11 */ 106 .word handle_trap_reserved /* 12 */ 107 .word handle_trap_reserved /* 13 */ 108 .word handle_trap_reserved /* 14 */ 109 .word handle_trap_reserved /* 15 */ 110 .word handle_trap_reserved /* 16 */ 111 .word handle_trap_reserved /* 17 */ 112 .word handle_trap_reserved /* 18 */ 113 .word handle_trap_reserved /* 19 */ 114 .word handle_trap_reserved /* 20 */ 115 .word handle_trap_reserved /* 21 */ 116 .word handle_trap_reserved /* 22 */ 117 .word handle_trap_reserved /* 23 */ 118 .word handle_trap_reserved /* 24 */ 119 .word handle_trap_reserved /* 25 */ 120 .word handle_trap_reserved /* 26 */ 121 .word handle_trap_reserved /* 27 */ 122 .word handle_trap_reserved /* 28 */ 123 .word handle_trap_reserved /* 29 */ 124#ifdef CONFIG_KGDB 125 .word handle_kgdb_breakpoint /* 30 KGDB breakpoint */ 126#else 127 .word instruction_trap /* 30 */ 128#endif 129 .word handle_breakpoint /* 31 */ 130 131.text 132.set noat 133.set nobreak 134 135ENTRY(inthandler) 136 SAVE_ALL 137 138 kuser_cmpxchg_check 139 140 /* Clear EH bit before we get a new excpetion in the kernel 141 * and after we have saved it to the exception frame. This is done 142 * whether it's trap, tlb-miss or interrupt. If we don't do this 143 * estatus is not updated the next exception. 144 */ 145 rdctl r24, status 146 movi r9, %lo(~STATUS_EH) 147 and r24, r24, r9 148 wrctl status, r24 149 150 /* Read cause and vector and branch to the associated handler */ 151 mov r4, sp 152 rdctl r5, exception 153 movia r9, exception_table 154 add r24, r9, r5 155 ldw r24, 0(r24) 156 jmp r24 157 158 159/*********************************************************************** 160 * Handle traps 161 *********************************************************************** 162 */ 163ENTRY(handle_trap) 164 ldwio r24, -4(ea) /* instruction that caused the exception */ 165 srli r24, r24, 4 166 andi r24, r24, 0x7c 167 movia r9,trap_table 168 add r24, r24, r9 169 ldw r24, 0(r24) 170 jmp r24 171 172 173/*********************************************************************** 174 * Handle system calls 175 *********************************************************************** 176 */ 177ENTRY(handle_system_call) 178 /* Enable interrupts */ 179 rdctl r10, status 180 ori r10, r10, STATUS_PIE 181 wrctl status, r10 182 183 /* Reload registers destroyed by common code. */ 184 ldw r4, PT_R4(sp) 185 ldw r5, PT_R5(sp) 186 187local_restart: 188 /* Check that the requested system call is within limits */ 189 movui r1, __NR_syscalls 190 bgeu r2, r1, ret_invsyscall 191 slli r1, r2, 2 192 movhi r11, %hiadj(sys_call_table) 193 add r1, r1, r11 194 ldw r1, %lo(sys_call_table)(r1) 195 beq r1, r0, ret_invsyscall 196 197 /* Check if we are being traced */ 198 GET_THREAD_INFO r11 199 ldw r11,TI_FLAGS(r11) 200 BTBNZ r11,r11,TIF_SYSCALL_TRACE,traced_system_call 201 202 /* Execute the system call */ 203 callr r1 204 205 /* If the syscall returns a negative result: 206 * Set r7 to 1 to indicate error, 207 * Negate r2 to get a positive error code 208 * If the syscall returns zero or a positive value: 209 * Set r7 to 0. 210 * The sigreturn system calls will skip the code below by 211 * adding to register ra. To avoid destroying registers 212 */ 213translate_rc_and_ret: 214 movi r1, 0 215 bge r2, zero, 3f 216 sub r2, zero, r2 217 movi r1, 1 2183: 219 stw r2, PT_R2(sp) 220 stw r1, PT_R7(sp) 221end_translate_rc_and_ret: 222 223ret_from_exception: 224 ldw r1, PT_ESTATUS(sp) 225 /* if so, skip resched, signals */ 226 TSTBNZ r1, r1, ESTATUS_EU, Luser_return 227 228restore_all: 229 rdctl r10, status /* disable intrs */ 230 andi r10, r10, %lo(~STATUS_PIE) 231 wrctl status, r10 232 RESTORE_ALL 233 eret 234 235 /* If the syscall number was invalid return ENOSYS */ 236ret_invsyscall: 237 movi r2, -ENOSYS 238 br translate_rc_and_ret 239 240 /* This implements the same as above, except it calls 241 * do_syscall_trace_enter and do_syscall_trace_exit before and after the 242 * syscall in order for utilities like strace and gdb to work. 243 */ 244traced_system_call: 245 SAVE_SWITCH_STACK 246 call do_syscall_trace_enter 247 RESTORE_SWITCH_STACK 248 249 /* Create system call register arguments. The 5th and 6th 250 arguments on stack are already in place at the beginning 251 of pt_regs. */ 252 ldw r2, PT_R2(sp) 253 ldw r4, PT_R4(sp) 254 ldw r5, PT_R5(sp) 255 ldw r6, PT_R6(sp) 256 ldw r7, PT_R7(sp) 257 258 /* Fetch the syscall function, we don't need to check the boundaries 259 * since this is already done. 260 */ 261 slli r1, r2, 2 262 movhi r11,%hiadj(sys_call_table) 263 add r1, r1, r11 264 ldw r1, %lo(sys_call_table)(r1) 265 266 callr r1 267 268 /* If the syscall returns a negative result: 269 * Set r7 to 1 to indicate error, 270 * Negate r2 to get a positive error code 271 * If the syscall returns zero or a positive value: 272 * Set r7 to 0. 273 * The sigreturn system calls will skip the code below by 274 * adding to register ra. To avoid destroying registers 275 */ 276translate_rc_and_ret2: 277 movi r1, 0 278 bge r2, zero, 4f 279 sub r2, zero, r2 280 movi r1, 1 2814: 282 stw r2, PT_R2(sp) 283 stw r1, PT_R7(sp) 284end_translate_rc_and_ret2: 285 SAVE_SWITCH_STACK 286 call do_syscall_trace_exit 287 RESTORE_SWITCH_STACK 288 br ret_from_exception 289 290Luser_return: 291 GET_THREAD_INFO r11 /* get thread_info pointer */ 292 ldw r10, TI_FLAGS(r11) /* get thread_info->flags */ 293 ANDI32 r11, r10, _TIF_WORK_MASK 294 beq r11, r0, restore_all /* Nothing to do */ 295 BTBZ r1, r10, TIF_NEED_RESCHED, Lsignal_return 296 297 /* Reschedule work */ 298 call schedule 299 br ret_from_exception 300 301Lsignal_return: 302 ANDI32 r1, r10, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME 303 beq r1, r0, restore_all 304 mov r4, sp /* pt_regs */ 305 SAVE_SWITCH_STACK 306 call do_notify_resume 307 beq r2, r0, no_work_pending 308 RESTORE_SWITCH_STACK 309 /* prepare restart syscall here without leaving kernel */ 310 ldw r2, PT_R2(sp) /* reload syscall number in r2 */ 311 ldw r4, PT_R4(sp) /* reload syscall arguments r4-r9 */ 312 ldw r5, PT_R5(sp) 313 ldw r6, PT_R6(sp) 314 ldw r7, PT_R7(sp) 315 ldw r8, PT_R8(sp) 316 ldw r9, PT_R9(sp) 317 br local_restart /* restart syscall */ 318 319no_work_pending: 320 RESTORE_SWITCH_STACK 321 br ret_from_exception 322 323/*********************************************************************** 324 * Handle external interrupts. 325 *********************************************************************** 326 */ 327/* 328 * This is the generic interrupt handler (for all hardware interrupt 329 * sources). It figures out the vector number and calls the appropriate 330 * interrupt service routine directly. 331 */ 332external_interrupt: 333 rdctl r12, ipending 334 rdctl r9, ienable 335 and r12, r12, r9 336 /* skip if no interrupt is pending */ 337 beq r12, r0, ret_from_interrupt 338 339 movi r24, -1 340 stw r24, PT_ORIG_R2(sp) 341 342 /* 343 * Process an external hardware interrupt. 344 */ 345 346 addi ea, ea, -4 /* re-issue the interrupted instruction */ 347 stw ea, PT_EA(sp) 3482: movi r4, %lo(-1) /* Start from bit position 0, 349 highest priority */ 350 /* This is the IRQ # for handler call */ 3511: andi r10, r12, 1 /* Isolate bit we are interested in */ 352 srli r12, r12, 1 /* shift count is costly without hardware 353 multiplier */ 354 addi r4, r4, 1 355 beq r10, r0, 1b 356 mov r5, sp /* Setup pt_regs pointer for handler call */ 357 call do_IRQ 358 rdctl r12, ipending /* check again if irq still pending */ 359 rdctl r9, ienable /* Isolate possible interrupts */ 360 and r12, r12, r9 361 bne r12, r0, 2b 362 /* br ret_from_interrupt */ /* fall through to ret_from_interrupt */ 363 364ENTRY(ret_from_interrupt) 365 ldw r1, PT_ESTATUS(sp) /* check if returning to kernel */ 366 TSTBNZ r1, r1, ESTATUS_EU, Luser_return 367 368#ifdef CONFIG_PREEMPT 369 GET_THREAD_INFO r1 370 ldw r4, TI_PREEMPT_COUNT(r1) 371 bne r4, r0, restore_all 372 ldw r4, TI_FLAGS(r1) /* ? Need resched set */ 373 BTBZ r10, r4, TIF_NEED_RESCHED, restore_all 374 ldw r4, PT_ESTATUS(sp) /* ? Interrupts off */ 375 andi r10, r4, ESTATUS_EPIE 376 beq r10, r0, restore_all 377 call preempt_schedule_irq 378#endif 379 br restore_all 380 381/*********************************************************************** 382 * A few syscall wrappers 383 *********************************************************************** 384 */ 385/* 386 * int clone(unsigned long clone_flags, unsigned long newsp, 387 * int __user * parent_tidptr, int __user * child_tidptr, 388 * int tls_val) 389 */ 390ENTRY(sys_clone) 391 SAVE_SWITCH_STACK 392 addi sp, sp, -4 393 stw r7, 0(sp) /* Pass 5th arg thru stack */ 394 mov r7, r6 /* 4th arg is 3rd of clone() */ 395 mov r6, zero /* 3rd arg always 0 */ 396 call do_fork 397 addi sp, sp, 4 398 RESTORE_SWITCH_STACK 399 ret 400 401ENTRY(sys_rt_sigreturn) 402 SAVE_SWITCH_STACK 403 mov r4, sp 404 call do_rt_sigreturn 405 RESTORE_SWITCH_STACK 406 addi ra, ra, (end_translate_rc_and_ret - translate_rc_and_ret) 407 ret 408 409/*********************************************************************** 410 * A few other wrappers and stubs 411 *********************************************************************** 412 */ 413protection_exception_pte: 414 rdctl r6, pteaddr 415 slli r6, r6, 10 416 call do_page_fault 417 br ret_from_exception 418 419protection_exception_ba: 420 rdctl r6, badaddr 421 call do_page_fault 422 br ret_from_exception 423 424protection_exception_instr: 425 call handle_supervisor_instr 426 br ret_from_exception 427 428handle_breakpoint: 429 call breakpoint_c 430 br ret_from_exception 431 432#ifdef CONFIG_NIOS2_ALIGNMENT_TRAP 433handle_unaligned: 434 SAVE_SWITCH_STACK 435 call handle_unaligned_c 436 RESTORE_SWITCH_STACK 437 br ret_from_exception 438#else 439handle_unaligned: 440 call handle_unaligned_c 441 br ret_from_exception 442#endif 443 444handle_illegal: 445 call handle_illegal_c 446 br ret_from_exception 447 448handle_diverror: 449 call handle_diverror_c 450 br ret_from_exception 451 452#ifdef CONFIG_KGDB 453handle_kgdb_breakpoint: 454 call kgdb_breakpoint_c 455 br ret_from_exception 456#endif 457 458handle_trap_1: 459 call handle_trap_1_c 460 br ret_from_exception 461 462handle_trap_2: 463 call handle_trap_2_c 464 br ret_from_exception 465 466handle_trap_3: 467handle_trap_reserved: 468 call handle_trap_3_c 469 br ret_from_exception 470 471/* 472 * Beware - when entering resume, prev (the current task) is 473 * in r4, next (the new task) is in r5, don't change these 474 * registers. 475 */ 476ENTRY(resume) 477 478 rdctl r7, status /* save thread status reg */ 479 stw r7, TASK_THREAD + THREAD_KPSR(r4) 480 481 andi r7, r7, %lo(~STATUS_PIE) /* disable interrupts */ 482 wrctl status, r7 483 484 SAVE_SWITCH_STACK 485 stw sp, TASK_THREAD + THREAD_KSP(r4)/* save kernel stack pointer */ 486 ldw sp, TASK_THREAD + THREAD_KSP(r5)/* restore new thread stack */ 487 movia r24, _current_thread /* save thread */ 488 GET_THREAD_INFO r1 489 stw r1, 0(r24) 490 RESTORE_SWITCH_STACK 491 492 ldw r7, TASK_THREAD + THREAD_KPSR(r5)/* restore thread status reg */ 493 wrctl status, r7 494 ret 495 496ENTRY(ret_from_fork) 497 call schedule_tail 498 br ret_from_exception 499 500ENTRY(ret_from_kernel_thread) 501 call schedule_tail 502 mov r4,r17 /* arg */ 503 callr r16 /* function */ 504 br ret_from_exception 505 506/* 507 * Kernel user helpers. 508 * 509 * Each segment is 64-byte aligned and will be mapped to the <User space>. 510 * New segments (if ever needed) must be added after the existing ones. 511 * This mechanism should be used only for things that are really small and 512 * justified, and not be abused freely. 513 * 514 */ 515 516 /* Filling pads with undefined instructions. */ 517.macro kuser_pad sym size 518 .if ((. - \sym) & 3) 519 .rept (4 - (. - \sym) & 3) 520 .byte 0 521 .endr 522 .endif 523 .rept ((\size - (. - \sym)) / 4) 524 .word 0xdeadbeef 525 .endr 526.endm 527 528 .align 6 529 .globl __kuser_helper_start 530__kuser_helper_start: 531 532__kuser_helper_version: /* @ 0x1000 */ 533 .word ((__kuser_helper_end - __kuser_helper_start) >> 6) 534 535__kuser_cmpxchg: /* @ 0x1004 */ 536 /* 537 * r4 pointer to exchange variable 538 * r5 old value 539 * r6 new value 540 */ 541cmpxchg_ldw: 542 ldw r2, 0(r4) /* load current value */ 543 sub r2, r2, r5 /* compare with old value */ 544 bne r2, zero, cmpxchg_ret 545 546 /* We had a match, store the new value */ 547cmpxchg_stw: 548 stw r6, 0(r4) 549cmpxchg_ret: 550 ret 551 552 kuser_pad __kuser_cmpxchg, 64 553 554 .globl __kuser_sigtramp 555__kuser_sigtramp: 556 movi r2, __NR_rt_sigreturn 557 trap 558 559 kuser_pad __kuser_sigtramp, 64 560 561 .globl __kuser_helper_end 562__kuser_helper_end: 563