1/* 2 * Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARCompact ISA 3 * 4 * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com) 5 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * vineetg: May 2011 12 * -Userspace unaligned access emulation 13 * 14 * vineetg: Feb 2011 (ptrace low level code fixes) 15 * -traced syscall return code (r0) was not saved into pt_regs for restoring 16 * into user reg-file when traded task rets to user space. 17 * -syscalls needing arch-wrappers (mainly for passing sp as pt_regs) 18 * were not invoking post-syscall trace hook (jumping directly into 19 * ret_from_system_call) 20 * 21 * vineetg: Nov 2010: 22 * -Vector table jumps (@8 bytes) converted into branches (@4 bytes) 23 * -To maintain the slot size of 8 bytes/vector, added nop, which is 24 * not executed at runtime. 25 * 26 * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK) 27 * -do_signal()invoked upon TIF_RESTORE_SIGMASK as well 28 * -Wrappers for sys_{,rt_}sigsuspend() nolonger needed as they don't 29 * need ptregs anymore 30 * 31 * Vineetg: Oct 2009 32 * -In a rare scenario, Process gets a Priv-V exception and gets scheduled 33 * out. Since we don't do FAKE RTIE for Priv-V, CPU excpetion state remains 34 * active (AE bit enabled). This causes a double fault for a subseq valid 35 * exception. Thus FAKE RTIE needed in low level Priv-Violation handler. 36 * Instr Error could also cause similar scenario, so same there as well. 37 * 38 * Vineetg: March 2009 (Supporting 2 levels of Interrupts) 39 * 40 * Vineetg: Aug 28th 2008: Bug #94984 41 * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap 42 * Normally CPU does this automatically, however when doing FAKE rtie, 43 * we need to explicitly do this. The problem in macros 44 * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit 45 * was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit, 46 * setting it and not clearing it clears ZOL context 47 * 48 * Vineetg: May 16th, 2008 49 * - r25 now contains the Current Task when in kernel 50 * 51 * Vineetg: Dec 22, 2007 52 * Minor Surgery of Low Level ISR to make it SMP safe 53 * - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR 54 * - _current_task is made an array of NR_CPUS 55 * - Access of _current_task wrapped inside a macro so that if hardware 56 * team agrees for a dedicated reg, no other code is touched 57 * 58 * Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004 59 */ 60 61#include <linux/errno.h> 62#include <linux/linkage.h> /* {EXTRY,EXIT} */ 63#include <asm/entry.h> 64#include <asm/irqflags.h> 65 66 .cpu A7 67 68;############################ Vector Table ################################# 69 70.macro VECTOR lbl 71#if 1 /* Just in case, build breaks */ 72 j \lbl 73#else 74 b \lbl 75 nop 76#endif 77.endm 78 79 .section .vector, "ax",@progbits 80 .align 4 81 82/* Each entry in the vector table must occupy 2 words. Since it is a jump 83 * across sections (.vector to .text) we are gauranteed that 'j somewhere' 84 * will use the 'j limm' form of the intrsuction as long as somewhere is in 85 * a section other than .vector. 86 */ 87 88; ********* Critical System Events ********************** 89VECTOR res_service ; 0x0, Reset Vector (0x0) 90VECTOR mem_service ; 0x8, Mem exception (0x1) 91VECTOR instr_service ; 0x10, Instrn Error (0x2) 92 93; ******************** Device ISRs ********************** 94#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS 95VECTOR handle_interrupt_level2 96#else 97VECTOR handle_interrupt_level1 98#endif 99 100.rept 28 101VECTOR handle_interrupt_level1 ; Other devices 102.endr 103 104/* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */ 105 106; ******************** Exceptions ********************** 107VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20) 108VECTOR EV_TLBMissI ; 0x108, Intruction TLB miss (0x21) 109VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22) 110VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23) 111 ; or Misaligned Access 112VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24) 113VECTOR EV_Trap ; 0x128, Trap exception (0x25) 114VECTOR EV_Extension ; 0x130, Extn Intruction Excp (0x26) 115 116.rept 24 117VECTOR reserved ; Reserved Exceptions 118.endr 119 120 121;##################### Scratch Mem for IRQ stack switching ############# 122 123ARCFP_DATA int1_saved_reg 124 .align 32 125 .type int1_saved_reg, @object 126 .size int1_saved_reg, 4 127int1_saved_reg: 128 .zero 4 129 130/* Each Interrupt level needs its own scratch */ 131ARCFP_DATA int2_saved_reg 132 .type int2_saved_reg, @object 133 .size int2_saved_reg, 4 134int2_saved_reg: 135 .zero 4 136 137; --------------------------------------------- 138 .section .text, "ax",@progbits 139 140 141reserved: 142 flag 1 ; Unexpected event, halt 143 144;##################### Interrupt Handling ############################## 145 146#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS 147; --------------------------------------------- 148; Level 2 ISR: Can interrupt a Level 1 ISR 149; --------------------------------------------- 150ENTRY(handle_interrupt_level2) 151 152 INTERRUPT_PROLOGUE 2 153 154 ;------------------------------------------------------ 155 ; if L2 IRQ interrupted a L1 ISR, disable preemption 156 ; 157 ; This is to avoid a potential L1-L2-L1 scenario 158 ; -L1 IRQ taken 159 ; -L2 interrupts L1 (before L1 ISR could run) 160 ; -preemption off IRQ, user task in syscall picked to run 161 ; -RTIE to userspace 162 ; Returns from L2 context fine 163 ; But both L1 and L2 re-enabled, so another L1 can be taken 164 ; while prev L1 is still unserviced 165 ; 166 ;------------------------------------------------------ 167 168 ; L2 interrupting L1 implies both L2 and L1 active 169 ; However both A2 and A1 are NOT set in STATUS32, thus 170 ; need to check STATUS32_L2 to determine if L1 was active 171 172 ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs) 173 bbit0 r9, STATUS_A1_BIT, 1f ; L1 not active when L2 IRQ, so normal 174 175 ; bump thread_info->preempt_count (Disable preemption) 176 GET_CURR_THR_INFO_FROM_SP r10 177 ld r9, [r10, THREAD_INFO_PREEMPT_COUNT] 178 add r9, r9, 1 179 st r9, [r10, THREAD_INFO_PREEMPT_COUNT] 180 1811: 182 ;------------------------------------------------------ 183 ; setup params for Linux common ISR and invoke it 184 ;------------------------------------------------------ 185 lr r0, [icause2] 186 and r0, r0, 0x1f 187 188 bl.d @arch_do_IRQ 189 mov r1, sp 190 191 mov r8,0x2 192 sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg 193 194 b ret_from_exception 195 196END(handle_interrupt_level2) 197 198#endif 199 200; --------------------------------------------- 201; User Mode Memory Bus Error Interrupt Handler 202; (Kernel mode memory errors handled via seperate exception vectors) 203; --------------------------------------------- 204ENTRY(mem_service) 205 206 INTERRUPT_PROLOGUE 2 207 208 mov r0, ilink2 209 mov r1, sp 210 211 ; User process needs to be killed with SIGBUS, but first need to get 212 ; out of the L2 interrupt context (drop to pure kernel mode) and jump 213 ; off to "C" code where SIGBUS in enqueued 214 lr r3, [status32] 215 bclr r3, r3, STATUS_A2_BIT 216 or r3, r3, (STATUS_E1_MASK|STATUS_E2_MASK) 217 sr r3, [status32_l2] 218 mov ilink2, 1f 219 rtie 2201: 221 bl do_memory_error 222 b ret_from_exception 223END(mem_service) 224 225; --------------------------------------------- 226; Level 1 ISR 227; --------------------------------------------- 228ENTRY(handle_interrupt_level1) 229 230 INTERRUPT_PROLOGUE 1 231 232 lr r0, [icause1] 233 and r0, r0, 0x1f 234 235#ifdef CONFIG_TRACE_IRQFLAGS 236 ; icause1 needs to be read early, before calling tracing, which 237 ; can clobber scratch regs, hence use of stack to stash it 238 push r0 239 TRACE_ASM_IRQ_DISABLE 240 pop r0 241#endif 242 243 bl.d @arch_do_IRQ 244 mov r1, sp 245 246 mov r8,0x1 247 sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg 248 249 b ret_from_exception 250END(handle_interrupt_level1) 251 252;################### Non TLB Exception Handling ############################# 253 254; --------------------------------------------- 255; Protection Violation Exception Handler 256; --------------------------------------------- 257 258ENTRY(EV_TLBProtV) 259 260 EXCEPTION_PROLOGUE 261 262 mov r2, r9 ; ECR set into r9 already 263 lr r0, [efa] ; Faulting Data address (not part of pt_regs saved above) 264 265 ; Exception auto-disables further Intr/exceptions. 266 ; Re-enable them by pretending to return from exception 267 ; (so rest of handler executes in pure K mode) 268 269 FAKE_RET_FROM_EXCPN 270 271 mov r1, sp ; Handle to pt_regs 272 273 ;------ (5) Type of Protection Violation? ---------- 274 ; 275 ; ProtV Hardware Exception is triggered for Access Faults of 2 types 276 ; -Access Violaton : 00_23_(00|01|02|03)_00 277 ; x r w r+w 278 ; -Unaligned Access : 00_23_04_00 279 ; 280 bbit1 r2, ECR_C_BIT_PROTV_MISALIG_DATA, 4f 281 282 ;========= (6a) Access Violation Processing ======== 283 bl do_page_fault 284 b ret_from_exception 285 286 ;========== (6b) Non aligned access ============ 2874: 288 289 SAVE_CALLEE_SAVED_USER 290 mov r2, sp ; callee_regs 291 292 bl do_misaligned_access 293 294 ; TBD: optimize - do this only if a callee reg was involved 295 ; either a dst of emulated LD/ST or src with address-writeback 296 RESTORE_CALLEE_SAVED_USER 297 298 b ret_from_exception 299 300END(EV_TLBProtV) 301 302; Wrapper for Linux page fault handler called from EV_TLBMiss* 303; Very similar to ProtV handler case (6a) above, but avoids the extra checks 304; for Misaligned access 305; 306ENTRY(call_do_page_fault) 307 308 EXCEPTION_PROLOGUE 309 lr r0, [efa] ; Faulting Data address 310 mov r1, sp 311 FAKE_RET_FROM_EXCPN 312 313 mov blink, ret_from_exception 314 b do_page_fault 315 316END(call_do_page_fault) 317 318;############# Common Handlers for ARCompact and ARCv2 ############## 319 320#include "entry.S" 321 322;############# Return from Intr/Excp/Trap (ARC Specifics) ############## 323; 324; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap) 325; IRQ shd definitely not happen between now and rtie 326; All 2 entry points to here already disable interrupts 327 328.Lrestore_regs: 329 330 # Interrpts are actually disabled from this point on, but will get 331 # reenabled after we return from interrupt/exception. 332 # But irq tracer needs to be told now... 333 TRACE_ASM_IRQ_ENABLE 334 335 lr r10, [status32] 336 337 ; Restore REG File. In case multiple Events outstanding, 338 ; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None 339 ; Note that we use realtime STATUS32 (not pt_regs->status32) to 340 ; decide that. 341 342 and.f 0, r10, (STATUS_A1_MASK|STATUS_A2_MASK) 343 bz .Lexcep_or_pure_K_ret 344 345 ; Returning from Interrupts (Level 1 or 2) 346 347#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS 348 349 ; Level 2 interrupt return Path - from hardware standpoint 350 bbit0 r10, STATUS_A2_BIT, not_level2_interrupt 351 352 ;------------------------------------------------------------------ 353 ; However the context returning might not have taken L2 intr itself 354 ; e.g. Task'A' user-code -> L2 intr -> schedule -> 'B' user-code ret 355 ; Special considerations needed for the context which took L2 intr 356 357 ld r9, [sp, PT_event] ; Ensure this is L2 intr context 358 brne r9, event_IRQ2, 149f 359 360 ;------------------------------------------------------------------ 361 ; if L2 IRQ interrupted an L1 ISR, we'd disabled preemption earlier 362 ; so that sched doesn't move to new task, causing L1 to be delayed 363 ; undeterministically. Now that we've achieved that, let's reset 364 ; things to what they were, before returning from L2 context 365 ;---------------------------------------------------------------- 366 367 ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs) 368 bbit0 r9, STATUS_A1_BIT, 149f ; L1 not active when L2 IRQ, so normal 369 370 ; decrement thread_info->preempt_count (re-enable preemption) 371 GET_CURR_THR_INFO_FROM_SP r10 372 ld r9, [r10, THREAD_INFO_PREEMPT_COUNT] 373 374 ; paranoid check, given A1 was active when A2 happened, preempt count 375 ; must not be 0 because we would have incremented it. 376 ; If this does happen we simply HALT as it means a BUG !!! 377 cmp r9, 0 378 bnz 2f 379 flag 1 380 3812: 382 sub r9, r9, 1 383 st r9, [r10, THREAD_INFO_PREEMPT_COUNT] 384 385149: 386 INTERRUPT_EPILOGUE 2 ; return from level 2 interrupt 387debug_marker_l2: 388 rtie 389 390not_level2_interrupt: 391 392#endif 393 394 INTERRUPT_EPILOGUE 1 ; return from level 1 interrupt 395debug_marker_l1: 396 rtie 397 398.Lexcep_or_pure_K_ret: 399 400 ;this case is for syscalls or Exceptions or pure kernel mode 401 402 EXCEPTION_EPILOGUE 403debug_marker_syscall: 404 rtie 405 406END(ret_from_exception) 407