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 instruction_trap /* 1 */ 96 .word instruction_trap /* 2 */ 97 .word instruction_trap /* 3 */ 98 .word instruction_trap /* 4 */ 99 .word instruction_trap /* 5 */ 100 .word instruction_trap /* 6 */ 101 .word instruction_trap /* 7 */ 102 .word instruction_trap /* 8 */ 103 .word instruction_trap /* 9 */ 104 .word instruction_trap /* 10 */ 105 .word instruction_trap /* 11 */ 106 .word instruction_trap /* 12 */ 107 .word instruction_trap /* 13 */ 108 .word instruction_trap /* 14 */ 109 .word instruction_trap /* 15 */ 110 .word instruction_trap /* 16 */ 111 .word instruction_trap /* 17 */ 112 .word instruction_trap /* 18 */ 113 .word instruction_trap /* 19 */ 114 .word instruction_trap /* 20 */ 115 .word instruction_trap /* 21 */ 116 .word instruction_trap /* 22 */ 117 .word instruction_trap /* 23 */ 118 .word instruction_trap /* 24 */ 119 .word instruction_trap /* 25 */ 120 .word instruction_trap /* 26 */ 121 .word instruction_trap /* 27 */ 122 .word instruction_trap /* 28 */ 123 .word instruction_trap /* 29 */ 124 .word instruction_trap /* 30 */ 125 .word handle_breakpoint /* 31 */ 126 127.text 128.set noat 129.set nobreak 130 131ENTRY(inthandler) 132 SAVE_ALL 133 134 kuser_cmpxchg_check 135 136 /* Clear EH bit before we get a new excpetion in the kernel 137 * and after we have saved it to the exception frame. This is done 138 * whether it's trap, tlb-miss or interrupt. If we don't do this 139 * estatus is not updated the next exception. 140 */ 141 rdctl r24, status 142 movi r9, %lo(~STATUS_EH) 143 and r24, r24, r9 144 wrctl status, r24 145 146 /* Read cause and vector and branch to the associated handler */ 147 mov r4, sp 148 rdctl r5, exception 149 movia r9, exception_table 150 add r24, r9, r5 151 ldw r24, 0(r24) 152 jmp r24 153 154 155/*********************************************************************** 156 * Handle traps 157 *********************************************************************** 158 */ 159ENTRY(handle_trap) 160 ldw r24, -4(ea) /* instruction that caused the exception */ 161 srli r24, r24, 4 162 andi r24, r24, 0x7c 163 movia r9,trap_table 164 add r24, r24, r9 165 ldw r24, 0(r24) 166 jmp r24 167 168 169/*********************************************************************** 170 * Handle system calls 171 *********************************************************************** 172 */ 173ENTRY(handle_system_call) 174 /* Enable interrupts */ 175 rdctl r10, status 176 ori r10, r10, STATUS_PIE 177 wrctl status, r10 178 179 /* Reload registers destroyed by common code. */ 180 ldw r4, PT_R4(sp) 181 ldw r5, PT_R5(sp) 182 183local_restart: 184 /* Check that the requested system call is within limits */ 185 movui r1, __NR_syscalls 186 bgeu r2, r1, ret_invsyscall 187 slli r1, r2, 2 188 movhi r11, %hiadj(sys_call_table) 189 add r1, r1, r11 190 ldw r1, %lo(sys_call_table)(r1) 191 beq r1, r0, ret_invsyscall 192 193 /* Check if we are being traced */ 194 GET_THREAD_INFO r11 195 ldw r11,TI_FLAGS(r11) 196 BTBNZ r11,r11,TIF_SYSCALL_TRACE,traced_system_call 197 198 /* Execute the system call */ 199 callr r1 200 201 /* If the syscall returns a negative result: 202 * Set r7 to 1 to indicate error, 203 * Negate r2 to get a positive error code 204 * If the syscall returns zero or a positive value: 205 * Set r7 to 0. 206 * The sigreturn system calls will skip the code below by 207 * adding to register ra. To avoid destroying registers 208 */ 209translate_rc_and_ret: 210 movi r1, 0 211 bge r2, zero, 3f 212 sub r2, zero, r2 213 movi r1, 1 2143: 215 stw r2, PT_R2(sp) 216 stw r1, PT_R7(sp) 217end_translate_rc_and_ret: 218 219ret_from_exception: 220 ldw r1, PT_ESTATUS(sp) 221 /* if so, skip resched, signals */ 222 TSTBNZ r1, r1, ESTATUS_EU, Luser_return 223 224restore_all: 225 rdctl r10, status /* disable intrs */ 226 andi r10, r10, %lo(~STATUS_PIE) 227 wrctl status, r10 228 RESTORE_ALL 229 eret 230 231 /* If the syscall number was invalid return ENOSYS */ 232ret_invsyscall: 233 movi r2, -ENOSYS 234 br translate_rc_and_ret 235 236 /* This implements the same as above, except it calls 237 * do_syscall_trace_enter and do_syscall_trace_exit before and after the 238 * syscall in order for utilities like strace and gdb to work. 239 */ 240traced_system_call: 241 SAVE_SWITCH_STACK 242 call do_syscall_trace_enter 243 RESTORE_SWITCH_STACK 244 245 /* Create system call register arguments. The 5th and 6th 246 arguments on stack are already in place at the beginning 247 of pt_regs. */ 248 ldw r2, PT_R2(sp) 249 ldw r4, PT_R4(sp) 250 ldw r5, PT_R5(sp) 251 ldw r6, PT_R6(sp) 252 ldw r7, PT_R7(sp) 253 254 /* Fetch the syscall function, we don't need to check the boundaries 255 * since this is already done. 256 */ 257 slli r1, r2, 2 258 movhi r11,%hiadj(sys_call_table) 259 add r1, r1, r11 260 ldw r1, %lo(sys_call_table)(r1) 261 262 callr r1 263 264 /* If the syscall returns a negative result: 265 * Set r7 to 1 to indicate error, 266 * Negate r2 to get a positive error code 267 * If the syscall returns zero or a positive value: 268 * Set r7 to 0. 269 * The sigreturn system calls will skip the code below by 270 * adding to register ra. To avoid destroying registers 271 */ 272translate_rc_and_ret2: 273 movi r1, 0 274 bge r2, zero, 4f 275 sub r2, zero, r2 276 movi r1, 1 2774: 278 stw r2, PT_R2(sp) 279 stw r1, PT_R7(sp) 280end_translate_rc_and_ret2: 281 SAVE_SWITCH_STACK 282 call do_syscall_trace_exit 283 RESTORE_SWITCH_STACK 284 br ret_from_exception 285 286Luser_return: 287 GET_THREAD_INFO r11 /* get thread_info pointer */ 288 ldw r10, TI_FLAGS(r11) /* get thread_info->flags */ 289 ANDI32 r11, r10, _TIF_WORK_MASK 290 beq r11, r0, restore_all /* Nothing to do */ 291 BTBZ r1, r10, TIF_NEED_RESCHED, Lsignal_return 292 293 /* Reschedule work */ 294 call schedule 295 br ret_from_exception 296 297Lsignal_return: 298 ANDI32 r1, r10, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME 299 beq r1, r0, restore_all 300 mov r4, sp /* pt_regs */ 301 SAVE_SWITCH_STACK 302 call do_notify_resume 303 beq r2, r0, no_work_pending 304 RESTORE_SWITCH_STACK 305 /* prepare restart syscall here without leaving kernel */ 306 ldw r2, PT_R2(sp) /* reload syscall number in r2 */ 307 ldw r4, PT_R4(sp) /* reload syscall arguments r4-r9 */ 308 ldw r5, PT_R5(sp) 309 ldw r6, PT_R6(sp) 310 ldw r7, PT_R7(sp) 311 ldw r8, PT_R8(sp) 312 ldw r9, PT_R9(sp) 313 br local_restart /* restart syscall */ 314 315no_work_pending: 316 RESTORE_SWITCH_STACK 317 br ret_from_exception 318 319/*********************************************************************** 320 * Handle external interrupts. 321 *********************************************************************** 322 */ 323/* 324 * This is the generic interrupt handler (for all hardware interrupt 325 * sources). It figures out the vector number and calls the appropriate 326 * interrupt service routine directly. 327 */ 328external_interrupt: 329 rdctl r12, ipending 330 rdctl r9, ienable 331 and r12, r12, r9 332 /* skip if no interrupt is pending */ 333 beq r12, r0, ret_from_interrupt 334 335 movi r24, -1 336 stw r24, PT_ORIG_R2(sp) 337 338 /* 339 * Process an external hardware interrupt. 340 */ 341 342 addi ea, ea, -4 /* re-issue the interrupted instruction */ 343 stw ea, PT_EA(sp) 3442: movi r4, %lo(-1) /* Start from bit position 0, 345 highest priority */ 346 /* This is the IRQ # for handler call */ 3471: andi r10, r12, 1 /* Isolate bit we are interested in */ 348 srli r12, r12, 1 /* shift count is costly without hardware 349 multiplier */ 350 addi r4, r4, 1 351 beq r10, r0, 1b 352 mov r5, sp /* Setup pt_regs pointer for handler call */ 353 call do_IRQ 354 rdctl r12, ipending /* check again if irq still pending */ 355 rdctl r9, ienable /* Isolate possible interrupts */ 356 and r12, r12, r9 357 bne r12, r0, 2b 358 /* br ret_from_interrupt */ /* fall through to ret_from_interrupt */ 359 360ENTRY(ret_from_interrupt) 361 ldw r1, PT_ESTATUS(sp) /* check if returning to kernel */ 362 TSTBNZ r1, r1, ESTATUS_EU, Luser_return 363 364#ifdef CONFIG_PREEMPT 365 GET_THREAD_INFO r1 366 ldw r4, TI_PREEMPT_COUNT(r1) 367 bne r4, r0, restore_all 368 ldw r4, TI_FLAGS(r1) /* ? Need resched set */ 369 BTBZ r10, r4, TIF_NEED_RESCHED, restore_all 370 ldw r4, PT_ESTATUS(sp) /* ? Interrupts off */ 371 andi r10, r4, ESTATUS_EPIE 372 beq r10, r0, restore_all 373 call preempt_schedule_irq 374#endif 375 br restore_all 376 377/*********************************************************************** 378 * A few syscall wrappers 379 *********************************************************************** 380 */ 381/* 382 * int clone(unsigned long clone_flags, unsigned long newsp, 383 * int __user * parent_tidptr, int __user * child_tidptr, 384 * int tls_val) 385 */ 386ENTRY(sys_clone) 387 SAVE_SWITCH_STACK 388 addi sp, sp, -4 389 stw r7, 0(sp) /* Pass 5th arg thru stack */ 390 mov r7, r6 /* 4th arg is 3rd of clone() */ 391 mov r6, zero /* 3rd arg always 0 */ 392 call do_fork 393 addi sp, sp, 4 394 RESTORE_SWITCH_STACK 395 ret 396 397ENTRY(sys_rt_sigreturn) 398 SAVE_SWITCH_STACK 399 mov r4, sp 400 call do_rt_sigreturn 401 RESTORE_SWITCH_STACK 402 addi ra, ra, (end_translate_rc_and_ret - translate_rc_and_ret) 403 ret 404 405/*********************************************************************** 406 * A few other wrappers and stubs 407 *********************************************************************** 408 */ 409protection_exception_pte: 410 rdctl r6, pteaddr 411 slli r6, r6, 10 412 call do_page_fault 413 br ret_from_exception 414 415protection_exception_ba: 416 rdctl r6, badaddr 417 call do_page_fault 418 br ret_from_exception 419 420protection_exception_instr: 421 call handle_supervisor_instr 422 br ret_from_exception 423 424handle_breakpoint: 425 call breakpoint_c 426 br ret_from_exception 427 428#ifdef CONFIG_NIOS2_ALIGNMENT_TRAP 429handle_unaligned: 430 SAVE_SWITCH_STACK 431 call handle_unaligned_c 432 RESTORE_SWITCH_STACK 433 br ret_from_exception 434#else 435handle_unaligned: 436 call handle_unaligned_c 437 br ret_from_exception 438#endif 439 440handle_illegal: 441 call handle_illegal_c 442 br ret_from_exception 443 444handle_diverror: 445 call handle_diverror_c 446 br ret_from_exception 447 448/* 449 * Beware - when entering resume, prev (the current task) is 450 * in r4, next (the new task) is in r5, don't change these 451 * registers. 452 */ 453ENTRY(resume) 454 455 rdctl r7, status /* save thread status reg */ 456 stw r7, TASK_THREAD + THREAD_KPSR(r4) 457 458 andi r7, r7, %lo(~STATUS_PIE) /* disable interrupts */ 459 wrctl status, r7 460 461 SAVE_SWITCH_STACK 462 stw sp, TASK_THREAD + THREAD_KSP(r4)/* save kernel stack pointer */ 463 ldw sp, TASK_THREAD + THREAD_KSP(r5)/* restore new thread stack */ 464 movia r24, _current_thread /* save thread */ 465 GET_THREAD_INFO r1 466 stw r1, 0(r24) 467 RESTORE_SWITCH_STACK 468 469 ldw r7, TASK_THREAD + THREAD_KPSR(r5)/* restore thread status reg */ 470 wrctl status, r7 471 ret 472 473ENTRY(ret_from_fork) 474 call schedule_tail 475 br ret_from_exception 476 477ENTRY(ret_from_kernel_thread) 478 call schedule_tail 479 mov r4,r17 /* arg */ 480 callr r16 /* function */ 481 br ret_from_exception 482 483/* 484 * Kernel user helpers. 485 * 486 * Each segment is 64-byte aligned and will be mapped to the <User space>. 487 * New segments (if ever needed) must be added after the existing ones. 488 * This mechanism should be used only for things that are really small and 489 * justified, and not be abused freely. 490 * 491 */ 492 493 /* Filling pads with undefined instructions. */ 494.macro kuser_pad sym size 495 .if ((. - \sym) & 3) 496 .rept (4 - (. - \sym) & 3) 497 .byte 0 498 .endr 499 .endif 500 .rept ((\size - (. - \sym)) / 4) 501 .word 0xdeadbeef 502 .endr 503.endm 504 505 .align 6 506 .globl __kuser_helper_start 507__kuser_helper_start: 508 509__kuser_helper_version: /* @ 0x1000 */ 510 .word ((__kuser_helper_end - __kuser_helper_start) >> 6) 511 512__kuser_cmpxchg: /* @ 0x1004 */ 513 /* 514 * r4 pointer to exchange variable 515 * r5 old value 516 * r6 new value 517 */ 518cmpxchg_ldw: 519 ldw r2, 0(r4) /* load current value */ 520 sub r2, r2, r5 /* compare with old value */ 521 bne r2, zero, cmpxchg_ret 522 523 /* We had a match, store the new value */ 524cmpxchg_stw: 525 stw r6, 0(r4) 526cmpxchg_ret: 527 ret 528 529 kuser_pad __kuser_cmpxchg, 64 530 531 .globl __kuser_sigtramp 532__kuser_sigtramp: 533 movi r2, __NR_rt_sigreturn 534 trap 535 536 kuser_pad __kuser_sigtramp, 64 537 538 .globl __kuser_helper_end 539__kuser_helper_end: 540