1/* 2 * Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARC 3 * 4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * vineetg: Nov 2010: 11 * -Vector table jumps (@8 bytes) converted into branches (@4 bytes) 12 * -To maintain the slot size of 8 bytes/vector, added nop, which is 13 * not executed at runtime. 14 * 15 * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK) 16 * -do_signal()invoked upon TIF_RESTORE_SIGMASK as well 17 * -Wrappers for sys_{,rt_}sigsuspend() nolonger needed as they don't 18 * need ptregs anymore 19 * 20 * Vineetg: Oct 2009 21 * -In a rare scenario, Process gets a Priv-V exception and gets scheduled 22 * out. Since we don't do FAKE RTIE for Priv-V, CPU excpetion state remains 23 * active (AE bit enabled). This causes a double fault for a subseq valid 24 * exception. Thus FAKE RTIE needed in low level Priv-Violation handler. 25 * Instr Error could also cause similar scenario, so same there as well. 26 * 27 * Vineetg: Aug 28th 2008: Bug #94984 28 * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap 29 * Normally CPU does this automatically, however when doing FAKE rtie, 30 * we need to explicitly do this. The problem in macros 31 * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit 32 * was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit, 33 * setting it and not clearing it clears ZOL context 34 * 35 * Vineetg: Dec 22, 2007 36 * Minor Surgery of Low Level ISR to make it SMP safe 37 * - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR 38 * - _current_task is made an array of NR_CPUS 39 * - Access of _current_task wrapped inside a macro so that if hardware 40 * team agrees for a dedicated reg, no other code is touched 41 * 42 * Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004 43 */ 44 45/*------------------------------------------------------------------ 46 * Function ABI 47 *------------------------------------------------------------------ 48 * 49 * Arguments r0 - r7 50 * Caller Saved Registers r0 - r12 51 * Callee Saved Registers r13- r25 52 * Global Pointer (gp) r26 53 * Frame Pointer (fp) r27 54 * Stack Pointer (sp) r28 55 * Interrupt link register (ilink1) r29 56 * Interrupt link register (ilink2) r30 57 * Branch link register (blink) r31 58 *------------------------------------------------------------------ 59 */ 60 61 .cpu A7 62 63;############################ Vector Table ################################# 64 65.macro VECTOR lbl 66#if 1 /* Just in case, build breaks */ 67 j \lbl 68#else 69 b \lbl 70 nop 71#endif 72.endm 73 74 .section .vector, "ax",@progbits 75 .align 4 76 77/* Each entry in the vector table must occupy 2 words. Since it is a jump 78 * across sections (.vector to .text) we are gauranteed that 'j somewhere' 79 * will use the 'j limm' form of the intrsuction as long as somewhere is in 80 * a section other than .vector. 81 */ 82 83; ********* Critical System Events ********************** 84VECTOR res_service ; 0x0, Restart Vector (0x0) 85VECTOR mem_service ; 0x8, Mem exception (0x1) 86VECTOR instr_service ; 0x10, Instrn Error (0x2) 87 88; ******************** Device ISRs ********************** 89VECTOR handle_interrupt_level1 90 91VECTOR handle_interrupt_level1 92 93VECTOR handle_interrupt_level1 94 95VECTOR handle_interrupt_level1 96 97.rept 25 98VECTOR handle_interrupt_level1 ; Other devices 99.endr 100 101/* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */ 102 103; ******************** Exceptions ********************** 104VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20) 105VECTOR EV_TLBMissI ; 0x108, Intruction TLB miss (0x21) 106VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22) 107VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23) 108 ; or Misaligned Access 109VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24) 110VECTOR EV_Trap ; 0x128, Trap exception (0x25) 111VECTOR EV_Extension ; 0x130, Extn Intruction Excp (0x26) 112 113.rept 24 114VECTOR reserved ; Reserved Exceptions 115.endr 116 117#include <linux/linkage.h> /* ARC_{EXTRY,EXIT} */ 118#include <asm/entry.h> /* SAVE_ALL_{INT1,INT2,TRAP...} */ 119#include <asm/errno.h> 120#include <asm/arcregs.h> 121#include <asm/irqflags.h> 122 123;##################### Scratch Mem for IRQ stack switching ############# 124 125 .section .data ; NOT .global 126 .align 32 127 .type int1_saved_reg, @object 128 .size int1_saved_reg, 4 129int1_saved_reg: 130 .zero 4 131 132; --------------------------------------------- 133 .section .text, "ax",@progbits 134 135res_service: ; processor restart 136 flag 0x1 ; not implemented 137 nop 138 nop 139 140reserved: ; processor restart 141 rtie ; jump to processor initializations 142 143;##################### Interrupt Handling ############################## 144 145; --------------------------------------------- 146; Level 1 ISR 147; --------------------------------------------- 148ARC_ENTRY handle_interrupt_level1 149 150 /* free up r9 as scratchpad */ 151 st r9, [@int1_saved_reg] 152 153 ;Which mode (user/kernel) was the system in when intr occured 154 lr r9, [status32_l1] 155 156 SWITCH_TO_KERNEL_STK 157 SAVE_ALL_INT1 158 159 lr r0, [icause1] 160 and r0, r0, 0x1f 161 162 bl.d @arch_do_IRQ 163 mov r1, sp 164 165 mov r8,0x1 166 sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg 167 168 b ret_from_exception 169ARC_EXIT handle_interrupt_level1 170 171;################### Non TLB Exception Handling ############################# 172 173; --------------------------------------------- 174; Instruction Error Exception Handler 175; --------------------------------------------- 176 177ARC_ENTRY instr_service 178 179 EXCPN_PROLOG_FREEUP_REG r9 180 181 lr r9, [erstatus] 182 183 SWITCH_TO_KERNEL_STK 184 SAVE_ALL_SYS 185 186 lr r0, [ecr] 187 lr r1, [efa] 188 189 mov r2, sp 190 191 FAKE_RET_FROM_EXCPN r9 192 193 bl do_insterror_or_kprobe 194 b ret_from_exception 195ARC_EXIT instr_service 196 197; --------------------------------------------- 198; Memory Error Exception Handler 199; --------------------------------------------- 200 201ARC_ENTRY mem_service 202 203 EXCPN_PROLOG_FREEUP_REG r9 204 205 lr r9, [erstatus] 206 207 SWITCH_TO_KERNEL_STK 208 SAVE_ALL_SYS 209 210 lr r0, [ecr] 211 lr r1, [efa] 212 mov r2, sp 213 bl do_memory_error 214 b ret_from_exception 215ARC_EXIT mem_service 216 217; --------------------------------------------- 218; Machine Check Exception Handler 219; --------------------------------------------- 220 221ARC_ENTRY EV_MachineCheck 222 223 EXCPN_PROLOG_FREEUP_REG r9 224 lr r9, [erstatus] 225 226 SWITCH_TO_KERNEL_STK 227 SAVE_ALL_SYS 228 229 lr r0, [ecr] 230 lr r1, [efa] 231 mov r2, sp 232 233 brne r0, 0x200100, 1f 234 bl do_tlb_overlap_fault 235 b ret_from_exception 236 2371: 238 ; DEAD END: can't do much, display Regs and HALT 239 SAVE_CALLEE_SAVED_USER 240 241 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 242 st sp, [r10, THREAD_CALLEE_REG] 243 244 j do_machine_check_fault 245 246ARC_EXIT EV_MachineCheck 247 248; --------------------------------------------- 249; Protection Violation Exception Handler 250; --------------------------------------------- 251 252ARC_ENTRY EV_TLBProtV 253 254 EXCPN_PROLOG_FREEUP_REG r9 255 256 ;Which mode (user/kernel) was the system in when Exception occured 257 lr r9, [erstatus] 258 259 SWITCH_TO_KERNEL_STK 260 SAVE_ALL_SYS 261 262 ;---------(3) Save some more regs----------------- 263 ; vineetg: Mar 6th: Random Seg Fault issue #1 264 ; ecr and efa were not saved in case an Intr sneaks in 265 ; after fake rtie 266 ; 267 lr r3, [ecr] 268 lr r4, [efa] 269 270 ; --------(4) Return from CPU Exception Mode --------- 271 ; Fake a rtie, but rtie to next label 272 ; That way, subsequently, do_page_fault ( ) executes in pure kernel 273 ; mode with further Exceptions enabled 274 275 FAKE_RET_FROM_EXCPN r9 276 277 ;------ (5) Type of Protection Violation? ---------- 278 ; 279 ; ProtV Hardware Exception is triggered for Access Faults of 2 types 280 ; -Access Violaton (WRITE to READ ONLY Page) - for linux COW 281 ; -Unaligned Access (READ/WRITE on odd boundary) 282 ; 283 cmp r3, 0x230400 ; Misaligned data access ? 284 beq 4f 285 286 ;========= (6a) Access Violation Processing ======== 287 cmp r3, 0x230100 288 mov r1, 0x0 ; if LD exception ? write = 0 289 mov.ne r1, 0x1 ; else write = 1 290 291 mov r2, r4 ; faulting address 292 mov r0, sp ; pt_regs 293 bl do_page_fault 294 b ret_from_exception 295 296 ;========== (6b) Non aligned access ============ 2974: 298 mov r0, r3 ; cause code 299 mov r1, r4 ; faulting address 300 mov r2, sp ; pt_regs 301 302 bl do_misaligned_access 303 b ret_from_exception 304 305ARC_EXIT EV_TLBProtV 306 307; --------------------------------------------- 308; Privilege Violation Exception Handler 309; --------------------------------------------- 310ARC_ENTRY EV_PrivilegeV 311 312 EXCPN_PROLOG_FREEUP_REG r9 313 314 lr r9, [erstatus] 315 316 SWITCH_TO_KERNEL_STK 317 SAVE_ALL_SYS 318 319 lr r0, [ecr] 320 lr r1, [efa] 321 mov r2, sp 322 323 FAKE_RET_FROM_EXCPN r9 324 325 bl do_privilege_fault 326 b ret_from_exception 327ARC_EXIT EV_PrivilegeV 328 329; --------------------------------------------- 330; Extension Instruction Exception Handler 331; --------------------------------------------- 332ARC_ENTRY EV_Extension 333 334 EXCPN_PROLOG_FREEUP_REG r9 335 lr r9, [erstatus] 336 337 SWITCH_TO_KERNEL_STK 338 SAVE_ALL_SYS 339 340 lr r0, [ecr] 341 lr r1, [efa] 342 mov r2, sp 343 bl do_extension_fault 344 b ret_from_exception 345ARC_EXIT EV_Extension 346 347;################### Break Point TRAP ########################## 348 349 ; ======= (5b) Trap is due to Break-Point ========= 350 351trap_with_param: 352 353 ; stop_pc info by gdb needs this info 354 st orig_r8_IS_BRKPT, [sp, PT_orig_r8] 355 356 mov r0, r12 357 lr r1, [efa] 358 mov r2, sp 359 360 ; Now that we have read EFA, its safe to do "fake" rtie 361 ; and get out of CPU exception mode 362 FAKE_RET_FROM_EXCPN r11 363 364 ; Save callee regs in case gdb wants to have a look 365 ; SP will grow up by size of CALLEE Reg-File 366 ; NOTE: clobbers r12 367 SAVE_CALLEE_SAVED_USER 368 369 ; save location of saved Callee Regs @ thread_struct->pc 370 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 371 st sp, [r10, THREAD_CALLEE_REG] 372 373 ; Call the trap handler 374 bl do_non_swi_trap 375 376 ; unwind stack to discard Callee saved Regs 377 DISCARD_CALLEE_SAVED_USER 378 379 b ret_from_exception 380 381;##################### Trap Handling ############################## 382; 383; EV_Trap caused by TRAP_S and TRAP0 instructions. 384;------------------------------------------------------------------ 385; (1) System Calls 386; :parameters in r0-r7. 387; :r8 has the system call number 388; (2) Break Points 389;------------------------------------------------------------------ 390 391ARC_ENTRY EV_Trap 392 393 ; Need at least 1 reg to code the early exception prolog 394 EXCPN_PROLOG_FREEUP_REG r9 395 396 ;Which mode (user/kernel) was the system in when intr occured 397 lr r9, [erstatus] 398 399 SWITCH_TO_KERNEL_STK 400 SAVE_ALL_TRAP 401 402 ;------- (4) What caused the Trap -------------- 403 lr r12, [ecr] 404 and.f 0, r12, ECR_PARAM_MASK 405 bnz trap_with_param 406 407 ; ======= (5a) Trap is due to System Call ======== 408 409 ; Before doing anything, return from CPU Exception Mode 410 FAKE_RET_FROM_EXCPN r11 411 412 ;============ This is normal System Call case ========== 413 ; Sys-call num shd not exceed the total system calls avail 414 cmp r8, NR_syscalls 415 mov.hi r0, -ENOSYS 416 bhi ret_from_system_call 417 418 ; Offset into the syscall_table and call handler 419 ld.as r9,[sys_call_table, r8] 420 jl [r9] ; Entry into Sys Call Handler 421 422 ; fall through to ret_from_system_call 423ARC_EXIT EV_Trap 424 425ARC_ENTRY ret_from_system_call 426 427 st r0, [sp, PT_r0] ; sys call return value in pt_regs 428 429 ; fall through yet again to ret_from_exception 430 431;############# Return from Intr/Excp/Trap (Linux Specifics) ############## 432; 433; If ret to user mode do we need to handle signals, schedule() et al. 434 435ARC_ENTRY ret_from_exception 436 437 ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32 438 ld r8, [sp, PT_status32] ; returning to User/Kernel Mode 439 440#ifdef CONFIG_PREEMPT 441 bbit0 r8, STATUS_U_BIT, resume_kernel_mode 442#else 443 bbit0 r8, STATUS_U_BIT, restore_regs 444#endif 445 446 ; Before returning to User mode check-for-and-complete any pending work 447 ; such as rescheduling/signal-delivery etc. 448resume_user_mode_begin: 449 450 ; Disable IRQs to ensures that chk for pending work itself is atomic 451 ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an 452 ; interim IRQ). 453 IRQ_DISABLE r10 454 455 ; Fast Path return to user mode if no pending work 456 GET_CURR_THR_INFO_FLAGS r9 457 and.f 0, r9, _TIF_WORK_MASK 458 bz restore_regs 459 460 ; --- (Slow Path #1) task preemption --- 461 bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals 462 mov blink, resume_user_mode_begin ; tail-call to U mode ret chks 463 b @schedule ; BTST+Bnz causes relo error in link 464 465.Lchk_pend_signals: 466 IRQ_ENABLE r10 467 468 ; --- (Slow Path #2) pending signal --- 469 mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume() 470 471 bbit0 r9, TIF_SIGPENDING, .Lchk_notify_resume 472 473 ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs 474 ; in pt_reg since the "C" ABI (kernel code) will automatically 475 ; save/restore callee-saved regs. 476 ; 477 ; However, here we need to explicitly save callee regs because 478 ; (i) If this signal causes coredump - full regfile needed 479 ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus 480 ; tracer might call PEEKUSR(CALLEE reg) 481 ; 482 ; NOTE: SP will grow up by size of CALLEE Reg-File 483 SAVE_CALLEE_SAVED_USER ; clobbers r12 484 485 ; save location of saved Callee Regs @ thread_struct->callee 486 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 487 st sp, [r10, THREAD_CALLEE_REG] 488 489 bl @do_signal 490 491 ; Ideally we want to discard the Callee reg above, however if this was 492 ; a tracing signal, tracer could have done a POKEUSR(CALLEE reg) 493 RESTORE_CALLEE_SAVED_USER 494 495 b resume_user_mode_begin ; loop back to start of U mode ret 496 497 ; --- (Slow Path #3) notify_resume --- 498.Lchk_notify_resume: 499 btst r9, TIF_NOTIFY_RESUME 500 blnz @do_notify_resume 501 b resume_user_mode_begin ; unconditionally back to U mode ret chks 502 ; for single exit point from this block 503 504#ifdef CONFIG_PREEMPT 505 506resume_kernel_mode: 507 508 ; Can't preempt if preemption disabled 509 GET_CURR_THR_INFO_FROM_SP r10 510 ld r8, [r10, THREAD_INFO_PREEMPT_COUNT] 511 brne r8, 0, restore_regs 512 513 ; check if this task's NEED_RESCHED flag set 514 ld r9, [r10, THREAD_INFO_FLAGS] 515 bbit0 r9, TIF_NEED_RESCHED, restore_regs 516 517 IRQ_DISABLE r9 518 519 ; Invoke PREEMPTION 520 bl preempt_schedule_irq 521 522 ; preempt_schedule_irq() always returns with IRQ disabled 523#endif 524 525 ; fall through 526 527;############# Return from Intr/Excp/Trap (ARC Specifics) ############## 528; 529; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap) 530; IRQ shd definitely not happen between now and rtie 531 532restore_regs : 533 534 ; Disable Interrupts while restoring reg-file back 535 ; XXX can this be optimised out 536 IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy 537 538 ; Restore REG File. In case multiple Events outstanding, 539 ; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None 540 ; Note that we use realtime STATUS32 (not pt_regs->status32) to 541 ; decide that. 542 543 ; if Returning from Exception 544 bbit0 r10, STATUS_AE_BIT, not_exception 545 RESTORE_ALL_SYS 546 rtie 547 548 ; Not Exception so maybe Interrupts (Level 1 or 2) 549 550not_exception: 551 552 bbit0 r10, STATUS_A1_BIT, not_level1_interrupt 553 554 ;return from level 1 555 556 RESTORE_ALL_INT1 557debug_marker_l1: 558 rtie 559 560not_level1_interrupt: 561 562 ;this case is for syscalls or Exceptions (with fake rtie) 563 564 RESTORE_ALL_SYS 565debug_marker_syscall: 566 rtie 567 568ARC_EXIT ret_from_exception 569 570ARC_ENTRY ret_from_fork 571 ; when the forked child comes here from the __switch_to function 572 ; r0 has the last task pointer. 573 ; put last task in scheduler queue 574 bl @schedule_tail 575 576 ; If kernel thread, jump to it's entry-point 577 ld r9, [sp, PT_status32] 578 brne r9, 0, 1f 579 580 jl.d [r14] 581 mov r0, r13 ; arg to payload 582 5831: 584 ; special case of kernel_thread entry point returning back due to 585 ; kernel_execve() - pretend return from syscall to ret to userland 586 b ret_from_exception 587ARC_EXIT ret_from_fork 588 589;################### Special Sys Call Wrappers ########################## 590 591; TBD: call do_fork directly from here 592ARC_ENTRY sys_fork_wrapper 593 SAVE_CALLEE_SAVED_USER 594 bl @sys_fork 595 DISCARD_CALLEE_SAVED_USER 596 597 b ret_from_system_call 598ARC_EXIT sys_fork_wrapper 599 600ARC_ENTRY sys_vfork_wrapper 601 SAVE_CALLEE_SAVED_USER 602 bl @sys_vfork 603 DISCARD_CALLEE_SAVED_USER 604 605 b ret_from_system_call 606ARC_EXIT sys_vfork_wrapper 607 608ARC_ENTRY sys_clone_wrapper 609 SAVE_CALLEE_SAVED_USER 610 bl @sys_clone 611 DISCARD_CALLEE_SAVED_USER 612 613 b ret_from_system_call 614ARC_EXIT sys_clone_wrapper 615