1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * Common Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARC 4 * (included from entry-<isa>.S 5 * 6 * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com) 7 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 8 */ 9 10/*------------------------------------------------------------------ 11 * Function ABI 12 *------------------------------------------------------------------ 13 * 14 * Arguments r0 - r7 15 * Caller Saved Registers r0 - r12 16 * Callee Saved Registers r13- r25 17 * Global Pointer (gp) r26 18 * Frame Pointer (fp) r27 19 * Stack Pointer (sp) r28 20 * Branch link register (blink) r31 21 *------------------------------------------------------------------ 22 */ 23 24;################### Special Sys Call Wrappers ########################## 25 26ENTRY(sys_clone_wrapper) 27 SAVE_CALLEE_SAVED_USER 28 bl @sys_clone 29 DISCARD_CALLEE_SAVED_USER 30 31 GET_CURR_THR_INFO_FLAGS r10 32 btst r10, TIF_SYSCALL_TRACE 33 bnz tracesys_exit 34 35 b .Lret_from_system_call 36END(sys_clone_wrapper) 37 38ENTRY(sys_clone3_wrapper) 39 SAVE_CALLEE_SAVED_USER 40 bl @sys_clone3 41 DISCARD_CALLEE_SAVED_USER 42 43 GET_CURR_THR_INFO_FLAGS r10 44 btst r10, TIF_SYSCALL_TRACE 45 bnz tracesys_exit 46 47 b .Lret_from_system_call 48END(sys_clone3_wrapper) 49 50ENTRY(ret_from_fork) 51 ; when the forked child comes here from the __switch_to function 52 ; r0 has the last task pointer. 53 ; put last task in scheduler queue 54 jl @schedule_tail 55 56 ld r9, [sp, PT_status32] 57 brne r9, 0, 1f 58 59 jl.d [r14] ; kernel thread entry point 60 mov r0, r13 ; (see PF_KTHREAD block in copy_thread) 61 621: 63 ; Return to user space 64 ; 1. Any forked task (Reach here via BRne above) 65 ; 2. First ever init task (Reach here via return from JL above) 66 ; This is the historic "kernel_execve" use-case, to return to init 67 ; user mode, in a round about way since that is always done from 68 ; a kernel thread which is executed via JL above but always returns 69 ; out whenever kernel_execve (now inline do_fork()) is involved 70 b ret_from_exception 71END(ret_from_fork) 72 73;################### Non TLB Exception Handling ############################# 74 75; --------------------------------------------- 76; Instruction Error Exception Handler 77; --------------------------------------------- 78 79ENTRY(instr_service) 80 81 EXCEPTION_PROLOGUE 82 83 lr r0, [efa] 84 mov r1, sp 85 86 FAKE_RET_FROM_EXCPN 87 88 bl do_insterror_or_kprobe 89 b ret_from_exception 90END(instr_service) 91 92; --------------------------------------------- 93; Machine Check Exception Handler 94; --------------------------------------------- 95 96ENTRY(EV_MachineCheck) 97 98 EXCEPTION_PROLOGUE 99 100 lr r2, [ecr] 101 lr r0, [efa] 102 mov r1, sp 103 104 ; hardware auto-disables MMU, re-enable it to allow kernel vaddr 105 ; access for say stack unwinding of modules for crash dumps 106 lr r3, [ARC_REG_PID] 107 or r3, r3, MMU_ENABLE 108 sr r3, [ARC_REG_PID] 109 110 lsr r3, r2, 8 111 bmsk r3, r3, 7 112 brne r3, ECR_C_MCHK_DUP_TLB, 1f 113 114 bl do_tlb_overlap_fault 115 b ret_from_exception 116 1171: 118 ; DEAD END: can't do much, display Regs and HALT 119 SAVE_CALLEE_SAVED_USER 120 121 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 122 st sp, [r10, THREAD_CALLEE_REG] 123 124 j do_machine_check_fault 125 126END(EV_MachineCheck) 127 128; --------------------------------------------- 129; Privilege Violation Exception Handler 130; --------------------------------------------- 131ENTRY(EV_PrivilegeV) 132 133 EXCEPTION_PROLOGUE 134 135 lr r0, [efa] 136 mov r1, sp 137 138 FAKE_RET_FROM_EXCPN 139 140 bl do_privilege_fault 141 b ret_from_exception 142END(EV_PrivilegeV) 143 144; --------------------------------------------- 145; Extension Instruction Exception Handler 146; --------------------------------------------- 147ENTRY(EV_Extension) 148 149 EXCEPTION_PROLOGUE 150 151 lr r0, [efa] 152 mov r1, sp 153 154 FAKE_RET_FROM_EXCPN 155 156 bl do_extension_fault 157 b ret_from_exception 158END(EV_Extension) 159 160;################ Trap Handling (Syscall, Breakpoint) ################## 161 162; --------------------------------------------- 163; syscall Tracing 164; --------------------------------------------- 165tracesys: 166 ; save EFA in case tracer wants the PC of traced task 167 ; using ERET won't work since next-PC has already committed 168 lr r12, [efa] 169 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11 170 st r12, [r11, THREAD_FAULT_ADDR] ; thread.fault_address 171 172 ; PRE Sys Call Ptrace hook 173 mov r0, sp ; pt_regs needed 174 bl @syscall_trace_entry 175 176 ; Tracing code now returns the syscall num (orig or modif) 177 mov r8, r0 178 179 ; Do the Sys Call as we normally would. 180 ; Validate the Sys Call number 181 cmp r8, NR_syscalls 182 mov.hi r0, -ENOSYS 183 bhi tracesys_exit 184 185 ; Restore the sys-call args. Mere invocation of the hook abv could have 186 ; clobbered them (since they are in scratch regs). The tracer could also 187 ; have deliberately changed the syscall args: r0-r7 188 ld r0, [sp, PT_r0] 189 ld r1, [sp, PT_r1] 190 ld r2, [sp, PT_r2] 191 ld r3, [sp, PT_r3] 192 ld r4, [sp, PT_r4] 193 ld r5, [sp, PT_r5] 194 ld r6, [sp, PT_r6] 195 ld r7, [sp, PT_r7] 196 ld.as r9, [sys_call_table, r8] 197 jl [r9] ; Entry into Sys Call Handler 198 199tracesys_exit: 200 st r0, [sp, PT_r0] ; sys call return value in pt_regs 201 202 ;POST Sys Call Ptrace Hook 203 bl @syscall_trace_exit 204 b ret_from_exception ; NOT ret_from_system_call at is saves r0 which 205 ; we'd done before calling post hook above 206 207; --------------------------------------------- 208; Breakpoint TRAP 209; --------------------------------------------- 210trap_with_param: 211 212 ; stop_pc info by gdb needs this info 213 lr r0, [efa] 214 mov r1, sp 215 216 ; Now that we have read EFA, it is safe to do "fake" rtie 217 ; and get out of CPU exception mode 218 FAKE_RET_FROM_EXCPN 219 220 ; Save callee regs in case gdb wants to have a look 221 ; SP will grow up by size of CALLEE Reg-File 222 ; NOTE: clobbers r12 223 SAVE_CALLEE_SAVED_USER 224 225 ; save location of saved Callee Regs @ thread_struct->pc 226 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 227 st sp, [r10, THREAD_CALLEE_REG] 228 229 ; Call the trap handler 230 bl do_non_swi_trap 231 232 ; unwind stack to discard Callee saved Regs 233 DISCARD_CALLEE_SAVED_USER 234 235 b ret_from_exception 236 237; --------------------------------------------- 238; syscall TRAP 239; ABI: (r0-r7) upto 8 args, (r8) syscall number 240; --------------------------------------------- 241 242ENTRY(EV_Trap) 243 244 EXCEPTION_PROLOGUE 245 246 ;============ TRAP 1 :breakpoints 247 ; Check ECR for trap with arg (PROLOGUE ensures r10 has ECR) 248 bmsk.f 0, r10, 7 249 bnz trap_with_param 250 251 ;============ TRAP (no param): syscall top level 252 253 ; First return from Exception to pure K mode (Exception/IRQs renabled) 254 FAKE_RET_FROM_EXCPN 255 256 ; If syscall tracing ongoing, invoke pre-post-hooks 257 GET_CURR_THR_INFO_FLAGS r10 258 btst r10, TIF_SYSCALL_TRACE 259 bnz tracesys ; this never comes back 260 261 ;============ Normal syscall case 262 263 ; syscall num shd not exceed the total system calls avail 264 cmp r8, NR_syscalls 265 mov.hi r0, -ENOSYS 266 bhi .Lret_from_system_call 267 268 ; Offset into the syscall_table and call handler 269 ld.as r9,[sys_call_table, r8] 270 jl [r9] ; Entry into Sys Call Handler 271 272.Lret_from_system_call: 273 274 st r0, [sp, PT_r0] ; sys call return value in pt_regs 275 276 ; fall through to ret_from_exception 277END(EV_Trap) 278 279;############# Return from Intr/Excp/Trap (Linux Specifics) ############## 280; 281; If ret to user mode do we need to handle signals, schedule() et al. 282 283ENTRY(ret_from_exception) 284 285 ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32 286 ld r8, [sp, PT_status32] ; returning to User/Kernel Mode 287 288 bbit0 r8, STATUS_U_BIT, resume_kernel_mode 289 290 ; Before returning to User mode check-for-and-complete any pending work 291 ; such as rescheduling/signal-delivery etc. 292resume_user_mode_begin: 293 294 ; Disable IRQs to ensures that chk for pending work itself is atomic 295 ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an 296 ; interim IRQ). 297 IRQ_DISABLE r10 298 299 ; Fast Path return to user mode if no pending work 300 GET_CURR_THR_INFO_FLAGS r9 301 and.f 0, r9, _TIF_WORK_MASK 302 bz .Lrestore_regs 303 304 ; --- (Slow Path #1) task preemption --- 305 bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals 306 mov blink, resume_user_mode_begin ; tail-call to U mode ret chks 307 j @schedule ; BTST+Bnz causes relo error in link 308 309.Lchk_pend_signals: 310 IRQ_ENABLE r10 311 312 ; --- (Slow Path #2) pending signal --- 313 mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume() 314 315 GET_CURR_THR_INFO_FLAGS r9 316 bbit0 r9, TIF_SIGPENDING, .Lchk_notify_resume 317 318 ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs 319 ; in pt_reg since the "C" ABI (kernel code) will automatically 320 ; save/restore callee-saved regs. 321 ; 322 ; However, here we need to explicitly save callee regs because 323 ; (i) If this signal causes coredump - full regfile needed 324 ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus 325 ; tracer might call PEEKUSR(CALLEE reg) 326 ; 327 ; NOTE: SP will grow up by size of CALLEE Reg-File 328 SAVE_CALLEE_SAVED_USER ; clobbers r12 329 330 ; save location of saved Callee Regs @ thread_struct->callee 331 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 332 st sp, [r10, THREAD_CALLEE_REG] 333 334 bl @do_signal 335 336 ; Ideally we want to discard the Callee reg above, however if this was 337 ; a tracing signal, tracer could have done a POKEUSR(CALLEE reg) 338 RESTORE_CALLEE_SAVED_USER 339 340 b resume_user_mode_begin ; loop back to start of U mode ret 341 342 ; --- (Slow Path #3) notify_resume --- 343.Lchk_notify_resume: 344 btst r9, TIF_NOTIFY_RESUME 345 blnz @do_notify_resume 346 b resume_user_mode_begin ; unconditionally back to U mode ret chks 347 ; for single exit point from this block 348 349resume_kernel_mode: 350 351 ; Disable Interrupts from this point on 352 ; CONFIG_PREEMPTION: This is a must for preempt_schedule_irq() 353 ; !CONFIG_PREEMPTION: To ensure restore_regs is intr safe 354 IRQ_DISABLE r9 355 356#ifdef CONFIG_PREEMPTION 357 358 ; Can't preempt if preemption disabled 359 GET_CURR_THR_INFO_FROM_SP r10 360 ld r8, [r10, THREAD_INFO_PREEMPT_COUNT] 361 brne r8, 0, .Lrestore_regs 362 363 ; check if this task's NEED_RESCHED flag set 364 ld r9, [r10, THREAD_INFO_FLAGS] 365 bbit0 r9, TIF_NEED_RESCHED, .Lrestore_regs 366 367 ; Invoke PREEMPTION 368 jl preempt_schedule_irq 369 370 ; preempt_schedule_irq() always returns with IRQ disabled 371#endif 372 373 b .Lrestore_regs 374 375##### DONT ADD CODE HERE - .Lrestore_regs actually follows in entry-<isa>.S 376 377