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 ; MC excpetions disable MMU 105 ARC_MMU_REENABLE r3 106 107 lsr r3, r2, 8 108 bmsk r3, r3, 7 109 brne r3, ECR_C_MCHK_DUP_TLB, 1f 110 111 bl do_tlb_overlap_fault 112 b ret_from_exception 113 1141: 115 ; DEAD END: can't do much, display Regs and HALT 116 SAVE_CALLEE_SAVED_USER 117 118 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 119 st sp, [r10, THREAD_CALLEE_REG] 120 121 j do_machine_check_fault 122 123END(EV_MachineCheck) 124 125; --------------------------------------------- 126; Privilege Violation Exception Handler 127; --------------------------------------------- 128ENTRY(EV_PrivilegeV) 129 130 EXCEPTION_PROLOGUE 131 132 lr r0, [efa] 133 mov r1, sp 134 135 FAKE_RET_FROM_EXCPN 136 137 bl do_privilege_fault 138 b ret_from_exception 139END(EV_PrivilegeV) 140 141; --------------------------------------------- 142; Extension Instruction Exception Handler 143; --------------------------------------------- 144ENTRY(EV_Extension) 145 146 EXCEPTION_PROLOGUE 147 148 lr r0, [efa] 149 mov r1, sp 150 151 FAKE_RET_FROM_EXCPN 152 153 bl do_extension_fault 154 b ret_from_exception 155END(EV_Extension) 156 157;################ Trap Handling (Syscall, Breakpoint) ################## 158 159; --------------------------------------------- 160; syscall Tracing 161; --------------------------------------------- 162tracesys: 163 ; save EFA in case tracer wants the PC of traced task 164 ; using ERET won't work since next-PC has already committed 165 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11 166 st r12, [r11, THREAD_FAULT_ADDR] ; thread.fault_address 167 168 ; PRE Sys Call Ptrace hook 169 mov r0, sp ; pt_regs needed 170 bl @syscall_trace_entry 171 172 ; Tracing code now returns the syscall num (orig or modif) 173 mov r8, r0 174 175 ; Do the Sys Call as we normally would. 176 ; Validate the Sys Call number 177 cmp r8, NR_syscalls - 1 178 mov.hi r0, -ENOSYS 179 bhi tracesys_exit 180 181 ; Restore the sys-call args. Mere invocation of the hook abv could have 182 ; clobbered them (since they are in scratch regs). The tracer could also 183 ; have deliberately changed the syscall args: r0-r7 184 ld r0, [sp, PT_r0] 185 ld r1, [sp, PT_r1] 186 ld r2, [sp, PT_r2] 187 ld r3, [sp, PT_r3] 188 ld r4, [sp, PT_r4] 189 ld r5, [sp, PT_r5] 190 ld r6, [sp, PT_r6] 191 ld r7, [sp, PT_r7] 192 ld.as r9, [sys_call_table, r8] 193 jl [r9] ; Entry into Sys Call Handler 194 195tracesys_exit: 196 st r0, [sp, PT_r0] ; sys call return value in pt_regs 197 198 ;POST Sys Call Ptrace Hook 199 mov r0, sp ; pt_regs needed 200 bl @syscall_trace_exit 201 b ret_from_exception ; NOT ret_from_system_call at is saves r0 which 202 ; we'd done before calling post hook above 203 204; --------------------------------------------- 205; Breakpoint TRAP 206; --------------------------------------------- 207trap_with_param: 208 mov r0, r12 ; EFA in case ptracer/gdb wants stop_pc 209 mov r1, sp 210 211 ; Save callee regs in case gdb wants to have a look 212 ; SP will grow up by size of CALLEE Reg-File 213 ; NOTE: clobbers r12 214 SAVE_CALLEE_SAVED_USER 215 216 ; save location of saved Callee Regs @ thread_struct->pc 217 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 218 st sp, [r10, THREAD_CALLEE_REG] 219 220 ; Call the trap handler 221 bl do_non_swi_trap 222 223 ; unwind stack to discard Callee saved Regs 224 DISCARD_CALLEE_SAVED_USER 225 226 b ret_from_exception 227 228; --------------------------------------------- 229; syscall TRAP 230; ABI: (r0-r7) upto 8 args, (r8) syscall number 231; --------------------------------------------- 232 233ENTRY(EV_Trap) 234 235 EXCEPTION_PROLOGUE 236 237 lr r12, [efa] 238 239 FAKE_RET_FROM_EXCPN 240 241 ;============ TRAP 1 :breakpoints 242 ; Check ECR for trap with arg (PROLOGUE ensures r10 has ECR) 243 bmsk.f 0, r10, 7 244 bnz trap_with_param 245 246 ;============ TRAP (no param): syscall top level 247 248 ; If syscall tracing ongoing, invoke pre-post-hooks 249 GET_CURR_THR_INFO_FLAGS r10 250 btst r10, TIF_SYSCALL_TRACE 251 bnz tracesys ; this never comes back 252 253 ;============ Normal syscall case 254 255 ; syscall num shd not exceed the total system calls avail 256 cmp r8, NR_syscalls - 1 257 mov.hi r0, -ENOSYS 258 bhi .Lret_from_system_call 259 260 ; Offset into the syscall_table and call handler 261 ld.as r9,[sys_call_table, r8] 262 jl [r9] ; Entry into Sys Call Handler 263 264.Lret_from_system_call: 265 266 st r0, [sp, PT_r0] ; sys call return value in pt_regs 267 268 ; fall through to ret_from_exception 269END(EV_Trap) 270 271;############# Return from Intr/Excp/Trap (Linux Specifics) ############## 272; 273; If ret to user mode do we need to handle signals, schedule() et al. 274 275ENTRY(ret_from_exception) 276 277 ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32 278 ld r8, [sp, PT_status32] ; returning to User/Kernel Mode 279 280 bbit0 r8, STATUS_U_BIT, resume_kernel_mode 281 282 ; Before returning to User mode check-for-and-complete any pending work 283 ; such as rescheduling/signal-delivery etc. 284resume_user_mode_begin: 285 286 ; Disable IRQs to ensures that chk for pending work itself is atomic 287 ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an 288 ; interim IRQ). 289 IRQ_DISABLE r10 290 291 ; Fast Path return to user mode if no pending work 292 GET_CURR_THR_INFO_FLAGS r9 293 and.f 0, r9, _TIF_WORK_MASK 294 bz .Lrestore_regs 295 296 ; --- (Slow Path #1) task preemption --- 297 bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals 298 mov blink, resume_user_mode_begin ; tail-call to U mode ret chks 299 j @schedule ; BTST+Bnz causes relo error in link 300 301.Lchk_pend_signals: 302 IRQ_ENABLE r10 303 304 ; --- (Slow Path #2) pending signal --- 305 mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume() 306 307 GET_CURR_THR_INFO_FLAGS r9 308 and.f 0, r9, _TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL 309 bz .Lchk_notify_resume 310 311 ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs 312 ; in pt_reg since the "C" ABI (kernel code) will automatically 313 ; save/restore callee-saved regs. 314 ; 315 ; However, here we need to explicitly save callee regs because 316 ; (i) If this signal causes coredump - full regfile needed 317 ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus 318 ; tracer might call PEEKUSR(CALLEE reg) 319 ; 320 ; NOTE: SP will grow up by size of CALLEE Reg-File 321 SAVE_CALLEE_SAVED_USER ; clobbers r12 322 323 ; save location of saved Callee Regs @ thread_struct->callee 324 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 325 st sp, [r10, THREAD_CALLEE_REG] 326 327 bl @do_signal 328 329 ; Ideally we want to discard the Callee reg above, however if this was 330 ; a tracing signal, tracer could have done a POKEUSR(CALLEE reg) 331 RESTORE_CALLEE_SAVED_USER 332 333 b resume_user_mode_begin ; loop back to start of U mode ret 334 335 ; --- (Slow Path #3) notify_resume --- 336.Lchk_notify_resume: 337 btst r9, TIF_NOTIFY_RESUME 338 blnz @do_notify_resume 339 b resume_user_mode_begin ; unconditionally back to U mode ret chks 340 ; for single exit point from this block 341 342resume_kernel_mode: 343 344 ; Disable Interrupts from this point on 345 ; CONFIG_PREEMPTION: This is a must for preempt_schedule_irq() 346 ; !CONFIG_PREEMPTION: To ensure restore_regs is intr safe 347 IRQ_DISABLE r9 348 349#ifdef CONFIG_PREEMPTION 350 351 ; Can't preempt if preemption disabled 352 GET_CURR_THR_INFO_FROM_SP r10 353 ld r8, [r10, THREAD_INFO_PREEMPT_COUNT] 354 brne r8, 0, .Lrestore_regs 355 356 ; check if this task's NEED_RESCHED flag set 357 ld r9, [r10, THREAD_INFO_FLAGS] 358 bbit0 r9, TIF_NEED_RESCHED, .Lrestore_regs 359 360 ; Invoke PREEMPTION 361 jl preempt_schedule_irq 362 363 ; preempt_schedule_irq() always returns with IRQ disabled 364#endif 365 366 b .Lrestore_regs 367 368##### DONT ADD CODE HERE - .Lrestore_regs actually follows in entry-<isa>.S 369 370