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 stw r2, PT_ORIG_R2(sp) 189 /* Check that the requested system call is within limits */ 190 movui r1, __NR_syscalls 191 bgeu r2, r1, ret_invsyscall 192 slli r1, r2, 2 193 movhi r11, %hiadj(sys_call_table) 194 add r1, r1, r11 195 ldw r1, %lo(sys_call_table)(r1) 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 ldw r1, PT_ORIG_R2(sp) 217 addi r1, r1, 1 218 beq r1, zero, 3f 219 sub r2, zero, r2 220 movi r1, 1 2213: 222 stw r2, PT_R2(sp) 223 stw r1, PT_R7(sp) 224end_translate_rc_and_ret: 225 226ret_from_exception: 227 ldw r1, PT_ESTATUS(sp) 228 /* if so, skip resched, signals */ 229 TSTBNZ r1, r1, ESTATUS_EU, Luser_return 230 231restore_all: 232 rdctl r10, status /* disable intrs */ 233 andi r10, r10, %lo(~STATUS_PIE) 234 wrctl status, r10 235 RESTORE_ALL 236 eret 237 238 /* If the syscall number was invalid return ENOSYS */ 239ret_invsyscall: 240 movi r2, -ENOSYS 241 br translate_rc_and_ret 242 243 /* This implements the same as above, except it calls 244 * do_syscall_trace_enter and do_syscall_trace_exit before and after the 245 * syscall in order for utilities like strace and gdb to work. 246 */ 247traced_system_call: 248 SAVE_SWITCH_STACK 249 call do_syscall_trace_enter 250 RESTORE_SWITCH_STACK 251 252 /* Create system call register arguments. The 5th and 6th 253 arguments on stack are already in place at the beginning 254 of pt_regs. */ 255 ldw r2, PT_R2(sp) 256 ldw r4, PT_R4(sp) 257 ldw r5, PT_R5(sp) 258 ldw r6, PT_R6(sp) 259 ldw r7, PT_R7(sp) 260 261 /* Fetch the syscall function. */ 262 movui r1, __NR_syscalls 263 bgeu r2, r1, traced_invsyscall 264 slli r1, r2, 2 265 movhi r11,%hiadj(sys_call_table) 266 add r1, r1, r11 267 ldw r1, %lo(sys_call_table)(r1) 268 269 callr r1 270 271 /* If the syscall returns a negative result: 272 * Set r7 to 1 to indicate error, 273 * Negate r2 to get a positive error code 274 * If the syscall returns zero or a positive value: 275 * Set r7 to 0. 276 * The sigreturn system calls will skip the code below by 277 * adding to register ra. To avoid destroying registers 278 */ 279translate_rc_and_ret2: 280 movi r1, 0 281 bge r2, zero, 4f 282 ldw r1, PT_ORIG_R2(sp) 283 addi r1, r1, 1 284 beq r1, zero, 4f 285 sub r2, zero, r2 286 movi r1, 1 2874: 288 stw r2, PT_R2(sp) 289 stw r1, PT_R7(sp) 290end_translate_rc_and_ret2: 291 SAVE_SWITCH_STACK 292 call do_syscall_trace_exit 293 RESTORE_SWITCH_STACK 294 br ret_from_exception 295 296 /* If the syscall number was invalid return ENOSYS */ 297traced_invsyscall: 298 movi r2, -ENOSYS 299 br translate_rc_and_ret2 300 301Luser_return: 302 GET_THREAD_INFO r11 /* get thread_info pointer */ 303 ldw r10, TI_FLAGS(r11) /* get thread_info->flags */ 304 ANDI32 r11, r10, _TIF_WORK_MASK 305 beq r11, r0, restore_all /* Nothing to do */ 306 BTBZ r1, r10, TIF_NEED_RESCHED, Lsignal_return 307 308 /* Reschedule work */ 309 call schedule 310 br ret_from_exception 311 312Lsignal_return: 313 ANDI32 r1, r10, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME 314 beq r1, r0, restore_all 315 mov r4, sp /* pt_regs */ 316 SAVE_SWITCH_STACK 317 call do_notify_resume 318 beq r2, r0, no_work_pending 319 RESTORE_SWITCH_STACK 320 /* prepare restart syscall here without leaving kernel */ 321 ldw r2, PT_R2(sp) /* reload syscall number in r2 */ 322 ldw r4, PT_R4(sp) /* reload syscall arguments r4-r9 */ 323 ldw r5, PT_R5(sp) 324 ldw r6, PT_R6(sp) 325 ldw r7, PT_R7(sp) 326 ldw r8, PT_R8(sp) 327 ldw r9, PT_R9(sp) 328 br local_restart /* restart syscall */ 329 330no_work_pending: 331 RESTORE_SWITCH_STACK 332 br ret_from_exception 333 334/*********************************************************************** 335 * Handle external interrupts. 336 *********************************************************************** 337 */ 338/* 339 * This is the generic interrupt handler (for all hardware interrupt 340 * sources). It figures out the vector number and calls the appropriate 341 * interrupt service routine directly. 342 */ 343external_interrupt: 344 rdctl r12, ipending 345 rdctl r9, ienable 346 and r12, r12, r9 347 /* skip if no interrupt is pending */ 348 beq r12, r0, ret_from_interrupt 349 350 /* 351 * Process an external hardware interrupt. 352 */ 353 354 addi ea, ea, -4 /* re-issue the interrupted instruction */ 355 stw ea, PT_EA(sp) 3562: movi r4, %lo(-1) /* Start from bit position 0, 357 highest priority */ 358 /* This is the IRQ # for handler call */ 3591: andi r10, r12, 1 /* Isolate bit we are interested in */ 360 srli r12, r12, 1 /* shift count is costly without hardware 361 multiplier */ 362 addi r4, r4, 1 363 beq r10, r0, 1b 364 mov r5, sp /* Setup pt_regs pointer for handler call */ 365 call do_IRQ 366 rdctl r12, ipending /* check again if irq still pending */ 367 rdctl r9, ienable /* Isolate possible interrupts */ 368 and r12, r12, r9 369 bne r12, r0, 2b 370 /* br ret_from_interrupt */ /* fall through to ret_from_interrupt */ 371 372ENTRY(ret_from_interrupt) 373 ldw r1, PT_ESTATUS(sp) /* check if returning to kernel */ 374 TSTBNZ r1, r1, ESTATUS_EU, Luser_return 375 376#ifdef CONFIG_PREEMPTION 377 GET_THREAD_INFO r1 378 ldw r4, TI_PREEMPT_COUNT(r1) 379 bne r4, r0, restore_all 380 ldw r4, TI_FLAGS(r1) /* ? Need resched set */ 381 BTBZ r10, r4, TIF_NEED_RESCHED, restore_all 382 ldw r4, PT_ESTATUS(sp) /* ? Interrupts off */ 383 andi r10, r4, ESTATUS_EPIE 384 beq r10, r0, restore_all 385 call preempt_schedule_irq 386#endif 387 br restore_all 388 389/*********************************************************************** 390 * A few syscall wrappers 391 *********************************************************************** 392 */ 393/* 394 * int clone(unsigned long clone_flags, unsigned long newsp, 395 * int __user * parent_tidptr, int __user * child_tidptr, 396 * int tls_val) 397 */ 398ENTRY(sys_clone) 399 SAVE_SWITCH_STACK 400 subi sp, sp, 4 /* make space for tls pointer */ 401 stw r8, 0(sp) /* pass tls pointer (r8) via stack (5th argument) */ 402 call nios2_clone 403 addi sp, sp, 4 404 RESTORE_SWITCH_STACK 405 ret 406 407ENTRY(sys_rt_sigreturn) 408 SAVE_SWITCH_STACK 409 mov r4, sp 410 call do_rt_sigreturn 411 RESTORE_SWITCH_STACK 412 addi ra, ra, (end_translate_rc_and_ret - translate_rc_and_ret) 413 ret 414 415/*********************************************************************** 416 * A few other wrappers and stubs 417 *********************************************************************** 418 */ 419protection_exception_pte: 420 rdctl r6, pteaddr 421 slli r6, r6, 10 422 call do_page_fault 423 br ret_from_exception 424 425protection_exception_ba: 426 rdctl r6, badaddr 427 call do_page_fault 428 br ret_from_exception 429 430protection_exception_instr: 431 call handle_supervisor_instr 432 br ret_from_exception 433 434handle_breakpoint: 435 call breakpoint_c 436 br ret_from_exception 437 438#ifdef CONFIG_NIOS2_ALIGNMENT_TRAP 439handle_unaligned: 440 SAVE_SWITCH_STACK 441 call handle_unaligned_c 442 RESTORE_SWITCH_STACK 443 br ret_from_exception 444#else 445handle_unaligned: 446 call handle_unaligned_c 447 br ret_from_exception 448#endif 449 450handle_illegal: 451 call handle_illegal_c 452 br ret_from_exception 453 454handle_diverror: 455 call handle_diverror_c 456 br ret_from_exception 457 458#ifdef CONFIG_KGDB 459handle_kgdb_breakpoint: 460 call kgdb_breakpoint_c 461 br ret_from_exception 462#endif 463 464handle_trap_1: 465 call handle_trap_1_c 466 br ret_from_exception 467 468handle_trap_2: 469 call handle_trap_2_c 470 br ret_from_exception 471 472handle_trap_3: 473handle_trap_reserved: 474 call handle_trap_3_c 475 br ret_from_exception 476 477/* 478 * Beware - when entering resume, prev (the current task) is 479 * in r4, next (the new task) is in r5, don't change these 480 * registers. 481 */ 482ENTRY(resume) 483 484 rdctl r7, status /* save thread status reg */ 485 stw r7, TASK_THREAD + THREAD_KPSR(r4) 486 487 andi r7, r7, %lo(~STATUS_PIE) /* disable interrupts */ 488 wrctl status, r7 489 490 SAVE_SWITCH_STACK 491 stw sp, TASK_THREAD + THREAD_KSP(r4)/* save kernel stack pointer */ 492 ldw sp, TASK_THREAD + THREAD_KSP(r5)/* restore new thread stack */ 493 movia r24, _current_thread /* save thread */ 494 GET_THREAD_INFO r1 495 stw r1, 0(r24) 496 RESTORE_SWITCH_STACK 497 498 ldw r7, TASK_THREAD + THREAD_KPSR(r5)/* restore thread status reg */ 499 wrctl status, r7 500 ret 501 502ENTRY(ret_from_fork) 503 call schedule_tail 504 br ret_from_exception 505 506ENTRY(ret_from_kernel_thread) 507 call schedule_tail 508 mov r4,r17 /* arg */ 509 callr r16 /* function */ 510 br ret_from_exception 511 512/* 513 * Kernel user helpers. 514 * 515 * Each segment is 64-byte aligned and will be mapped to the <User space>. 516 * New segments (if ever needed) must be added after the existing ones. 517 * This mechanism should be used only for things that are really small and 518 * justified, and not be abused freely. 519 * 520 */ 521 522 /* Filling pads with undefined instructions. */ 523.macro kuser_pad sym size 524 .if ((. - \sym) & 3) 525 .rept (4 - (. - \sym) & 3) 526 .byte 0 527 .endr 528 .endif 529 .rept ((\size - (. - \sym)) / 4) 530 .word 0xdeadbeef 531 .endr 532.endm 533 534 .align 6 535 .globl __kuser_helper_start 536__kuser_helper_start: 537 538__kuser_helper_version: /* @ 0x1000 */ 539 .word ((__kuser_helper_end - __kuser_helper_start) >> 6) 540 541__kuser_cmpxchg: /* @ 0x1004 */ 542 /* 543 * r4 pointer to exchange variable 544 * r5 old value 545 * r6 new value 546 */ 547cmpxchg_ldw: 548 ldw r2, 0(r4) /* load current value */ 549 sub r2, r2, r5 /* compare with old value */ 550 bne r2, zero, cmpxchg_ret 551 552 /* We had a match, store the new value */ 553cmpxchg_stw: 554 stw r6, 0(r4) 555cmpxchg_ret: 556 ret 557 558 kuser_pad __kuser_cmpxchg, 64 559 560 .globl __kuser_sigtramp 561__kuser_sigtramp: 562 movi r2, __NR_rt_sigreturn 563 trap 564 565 kuser_pad __kuser_sigtramp, 64 566 567 .globl __kuser_helper_end 568__kuser_helper_end: 569