1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARCompact ISA 4 * 5 * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com) 6 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 7 * 8 * vineetg: May 2011 9 * -Userspace unaligned access emulation 10 * 11 * vineetg: Feb 2011 (ptrace low level code fixes) 12 * -traced syscall return code (r0) was not saved into pt_regs for restoring 13 * into user reg-file when traded task rets to user space. 14 * -syscalls needing arch-wrappers (mainly for passing sp as pt_regs) 15 * were not invoking post-syscall trace hook (jumping directly into 16 * ret_from_system_call) 17 * 18 * vineetg: Nov 2010: 19 * -Vector table jumps (@8 bytes) converted into branches (@4 bytes) 20 * -To maintain the slot size of 8 bytes/vector, added nop, which is 21 * not executed at runtime. 22 * 23 * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK) 24 * -do_signal()invoked upon TIF_RESTORE_SIGMASK as well 25 * -Wrappers for sys_{,rt_}sigsuspend() no longer needed as they don't 26 * need ptregs anymore 27 * 28 * Vineetg: Oct 2009 29 * -In a rare scenario, Process gets a Priv-V exception and gets scheduled 30 * out. Since we don't do FAKE RTIE for Priv-V, CPU exception state remains 31 * active (AE bit enabled). This causes a double fault for a subseq valid 32 * exception. Thus FAKE RTIE needed in low level Priv-Violation handler. 33 * Instr Error could also cause similar scenario, so same there as well. 34 * 35 * Vineetg: March 2009 (Supporting 2 levels of Interrupts) 36 * 37 * Vineetg: Aug 28th 2008: Bug #94984 38 * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap 39 * Normally CPU does this automatically, however when doing FAKE rtie, 40 * we need to explicitly do this. The problem in macros 41 * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit 42 * was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit, 43 * setting it and not clearing it clears ZOL context 44 * 45 * Vineetg: May 16th, 2008 46 * - r25 now contains the Current Task when in kernel 47 * 48 * Vineetg: Dec 22, 2007 49 * Minor Surgery of Low Level ISR to make it SMP safe 50 * - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR 51 * - _current_task is made an array of NR_CPUS 52 * - Access of _current_task wrapped inside a macro so that if hardware 53 * team agrees for a dedicated reg, no other code is touched 54 * 55 * Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004 56 */ 57 58#include <linux/errno.h> 59#include <linux/linkage.h> /* {ENTRY,EXIT} */ 60#include <asm/entry.h> 61#include <asm/irqflags.h> 62 63 .cpu A7 64 65;############################ Vector Table ################################# 66 67.macro VECTOR lbl 68#if 1 /* Just in case, build breaks */ 69 j \lbl 70#else 71 b \lbl 72 nop 73#endif 74.endm 75 76 .section .vector, "ax",@progbits 77 .align 4 78 79/* Each entry in the vector table must occupy 2 words. Since it is a jump 80 * across sections (.vector to .text) we are guaranteed that 'j somewhere' 81 * will use the 'j limm' form of the instruction as long as somewhere is in 82 * a section other than .vector. 83 */ 84 85; ********* Critical System Events ********************** 86VECTOR res_service ; 0x0, Reset Vector (0x0) 87VECTOR mem_service ; 0x8, Mem exception (0x1) 88VECTOR instr_service ; 0x10, Instrn Error (0x2) 89 90; ******************** Device ISRs ********************** 91#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS 92VECTOR handle_interrupt_level2 93#else 94VECTOR handle_interrupt_level1 95#endif 96 97.rept 28 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, Instruction 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 Instruction Excp (0x26) 112 113.rept 24 114VECTOR reserved ; Reserved Exceptions 115.endr 116 117 118;##################### Scratch Mem for IRQ stack switching ############# 119 120ARCFP_DATA int1_saved_reg 121 .align 32 122 .type int1_saved_reg, @object 123 .size int1_saved_reg, 4 124int1_saved_reg: 125 .zero 4 126 127/* Each Interrupt level needs its own scratch */ 128ARCFP_DATA int2_saved_reg 129 .type int2_saved_reg, @object 130 .size int2_saved_reg, 4 131int2_saved_reg: 132 .zero 4 133 134; --------------------------------------------- 135 .section .text, "ax",@progbits 136 137 138reserved: 139 flag 1 ; Unexpected event, halt 140 141;##################### Interrupt Handling ############################## 142 143#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS 144; --------------------------------------------- 145; Level 2 ISR: Can interrupt a Level 1 ISR 146; --------------------------------------------- 147ENTRY(handle_interrupt_level2) 148 149 INTERRUPT_PROLOGUE 2 150 151 ;------------------------------------------------------ 152 ; if L2 IRQ interrupted a L1 ISR, disable preemption 153 ; 154 ; This is to avoid a potential L1-L2-L1 scenario 155 ; -L1 IRQ taken 156 ; -L2 interrupts L1 (before L1 ISR could run) 157 ; -preemption off IRQ, user task in syscall picked to run 158 ; -RTIE to userspace 159 ; Returns from L2 context fine 160 ; But both L1 and L2 re-enabled, so another L1 can be taken 161 ; while prev L1 is still unserviced 162 ; 163 ;------------------------------------------------------ 164 165 ; L2 interrupting L1 implies both L2 and L1 active 166 ; However both A2 and A1 are NOT set in STATUS32, thus 167 ; need to check STATUS32_L2 to determine if L1 was active 168 169 ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs) 170 bbit0 r9, STATUS_A1_BIT, 1f ; L1 not active when L2 IRQ, so normal 171 172 ; bump thread_info->preempt_count (Disable preemption) 173 GET_CURR_THR_INFO_FROM_SP r10 174 ld r9, [r10, THREAD_INFO_PREEMPT_COUNT] 175 add r9, r9, 1 176 st r9, [r10, THREAD_INFO_PREEMPT_COUNT] 177 1781: 179 ;------------------------------------------------------ 180 ; setup params for Linux common ISR and invoke it 181 ;------------------------------------------------------ 182 lr r0, [icause2] 183 and r0, r0, 0x1f 184 185 bl.d @arch_do_IRQ 186 mov r1, sp 187 188 mov r8,0x2 189 sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg 190 191 b ret_from_exception 192 193END(handle_interrupt_level2) 194 195#endif 196 197; --------------------------------------------- 198; User Mode Memory Bus Error Interrupt Handler 199; (Kernel mode memory errors handled via separate exception vectors) 200; --------------------------------------------- 201ENTRY(mem_service) 202 203 INTERRUPT_PROLOGUE 2 204 205 mov r0, ilink2 206 mov r1, sp 207 208 ; User process needs to be killed with SIGBUS, but first need to get 209 ; out of the L2 interrupt context (drop to pure kernel mode) and jump 210 ; off to "C" code where SIGBUS in enqueued 211 lr r3, [status32] 212 bclr r3, r3, STATUS_A2_BIT 213 or r3, r3, (STATUS_E1_MASK|STATUS_E2_MASK) 214 sr r3, [status32_l2] 215 mov ilink2, 1f 216 rtie 2171: 218 bl do_memory_error 219 b ret_from_exception 220END(mem_service) 221 222; --------------------------------------------- 223; Level 1 ISR 224; --------------------------------------------- 225ENTRY(handle_interrupt_level1) 226 227 INTERRUPT_PROLOGUE 1 228 229 lr r0, [icause1] 230 and r0, r0, 0x1f 231 232#ifdef CONFIG_TRACE_IRQFLAGS 233 ; icause1 needs to be read early, before calling tracing, which 234 ; can clobber scratch regs, hence use of stack to stash it 235 push r0 236 TRACE_ASM_IRQ_DISABLE 237 pop r0 238#endif 239 240 bl.d @arch_do_IRQ 241 mov r1, sp 242 243 mov r8,0x1 244 sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg 245 246 b ret_from_exception 247END(handle_interrupt_level1) 248 249;################### Non TLB Exception Handling ############################# 250 251; --------------------------------------------- 252; Protection Violation Exception Handler 253; --------------------------------------------- 254 255ENTRY(EV_TLBProtV) 256 257 EXCEPTION_PROLOGUE 258 259 mov r2, r9 ; ECR set into r9 already 260 lr r0, [efa] ; Faulting Data address (not part of pt_regs saved above) 261 262 ; Exception auto-disables further Intr/exceptions. 263 ; Re-enable them by pretending to return from exception 264 ; (so rest of handler executes in pure K mode) 265 266 FAKE_RET_FROM_EXCPN 267 268 mov r1, sp ; Handle to pt_regs 269 270 ;------ (5) Type of Protection Violation? ---------- 271 ; 272 ; ProtV Hardware Exception is triggered for Access Faults of 2 types 273 ; -Access Violation : 00_23_(00|01|02|03)_00 274 ; x r w r+w 275 ; -Unaligned Access : 00_23_04_00 276 ; 277 bbit1 r2, ECR_C_BIT_PROTV_MISALIG_DATA, 4f 278 279 ;========= (6a) Access Violation Processing ======== 280 bl do_page_fault 281 b ret_from_exception 282 283 ;========== (6b) Non aligned access ============ 2844: 285 286 SAVE_CALLEE_SAVED_USER 287 mov r2, sp ; callee_regs 288 289 bl do_misaligned_access 290 291 ; TBD: optimize - do this only if a callee reg was involved 292 ; either a dst of emulated LD/ST or src with address-writeback 293 RESTORE_CALLEE_SAVED_USER 294 295 b ret_from_exception 296 297END(EV_TLBProtV) 298 299; Wrapper for Linux page fault handler called from EV_TLBMiss* 300; Very similar to ProtV handler case (6a) above, but avoids the extra checks 301; for Misaligned access 302; 303ENTRY(call_do_page_fault) 304 305 EXCEPTION_PROLOGUE 306 lr r0, [efa] ; Faulting Data address 307 mov r1, sp 308 FAKE_RET_FROM_EXCPN 309 310 mov blink, ret_from_exception 311 b do_page_fault 312 313END(call_do_page_fault) 314 315;############# Common Handlers for ARCompact and ARCv2 ############## 316 317#include "entry.S" 318 319;############# Return from Intr/Excp/Trap (ARC Specifics) ############## 320; 321; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap) 322; IRQ shd definitely not happen between now and rtie 323; All 2 entry points to here already disable interrupts 324 325.Lrestore_regs: 326 327 # Interrupts are actually disabled from this point on, but will get 328 # reenabled after we return from interrupt/exception. 329 # But irq tracer needs to be told now... 330 TRACE_ASM_IRQ_ENABLE 331 332 lr r10, [status32] 333 334 ; Restore REG File. In case multiple Events outstanding, 335 ; use the same priority as rtie: EXCPN, L2 IRQ, L1 IRQ, None 336 ; Note that we use realtime STATUS32 (not pt_regs->status32) to 337 ; decide that. 338 339 and.f 0, r10, (STATUS_A1_MASK|STATUS_A2_MASK) 340 bz .Lexcep_or_pure_K_ret 341 342 ; Returning from Interrupts (Level 1 or 2) 343 344#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS 345 346 ; Level 2 interrupt return Path - from hardware standpoint 347 bbit0 r10, STATUS_A2_BIT, not_level2_interrupt 348 349 ;------------------------------------------------------------------ 350 ; However the context returning might not have taken L2 intr itself 351 ; e.g. Task'A' user-code -> L2 intr -> schedule -> 'B' user-code ret 352 ; Special considerations needed for the context which took L2 intr 353 354 ld r9, [sp, PT_event] ; Ensure this is L2 intr context 355 brne r9, event_IRQ2, 149f 356 357 ;------------------------------------------------------------------ 358 ; if L2 IRQ interrupted an L1 ISR, we'd disabled preemption earlier 359 ; so that sched doesn't move to new task, causing L1 to be delayed 360 ; undeterministically. Now that we've achieved that, let's reset 361 ; things to what they were, before returning from L2 context 362 ;---------------------------------------------------------------- 363 364 ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs) 365 bbit0 r9, STATUS_A1_BIT, 149f ; L1 not active when L2 IRQ, so normal 366 367 ; decrement thread_info->preempt_count (re-enable preemption) 368 GET_CURR_THR_INFO_FROM_SP r10 369 ld r9, [r10, THREAD_INFO_PREEMPT_COUNT] 370 371 ; paranoid check, given A1 was active when A2 happened, preempt count 372 ; must not be 0 because we would have incremented it. 373 ; If this does happen we simply HALT as it means a BUG !!! 374 cmp r9, 0 375 bnz 2f 376 flag 1 377 3782: 379 sub r9, r9, 1 380 st r9, [r10, THREAD_INFO_PREEMPT_COUNT] 381 382149: 383 INTERRUPT_EPILOGUE 2 ; return from level 2 interrupt 384debug_marker_l2: 385 rtie 386 387not_level2_interrupt: 388 389#endif 390 391 INTERRUPT_EPILOGUE 1 ; return from level 1 interrupt 392debug_marker_l1: 393 rtie 394 395.Lexcep_or_pure_K_ret: 396 397 ;this case is for syscalls or Exceptions or pure kernel mode 398 399 EXCEPTION_EPILOGUE 400debug_marker_syscall: 401 rtie 402 403END(ret_from_exception) 404