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 and.f 0, r10, _TIF_SYSCALL_WORK 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 and.f 0, r10, _TIF_SYSCALL_WORK 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 bl do_insterror_or_kprobe 84 b ret_from_exception 85END(instr_service) 86 87; --------------------------------------------- 88; Machine Check Exception Handler 89; --------------------------------------------- 90 91ENTRY(EV_MachineCheck) 92 93 EXCEPTION_PROLOGUE_KEEP_AE ; ECR returned in r10 94 95 lr r0, [efa] 96 mov r1, sp 97 98 ; MC exceptions disable MMU 99 ARC_MMU_REENABLE r3 100 101 lsr r3, r10, 8 102 bmsk r3, r3, 7 103 brne r3, ECR_C_MCHK_DUP_TLB, 1f 104 105 bl do_tlb_overlap_fault 106 b ret_from_exception 107 1081: 109 ; DEAD END: can't do much, display Regs and HALT 110 SAVE_CALLEE_SAVED_USER 111 112 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 113 st sp, [r10, THREAD_CALLEE_REG] 114 115 j do_machine_check_fault 116 117END(EV_MachineCheck) 118 119; --------------------------------------------- 120; Privilege Violation Exception Handler 121; --------------------------------------------- 122ENTRY(EV_PrivilegeV) 123 124 EXCEPTION_PROLOGUE 125 126 bl do_privilege_fault 127 b ret_from_exception 128END(EV_PrivilegeV) 129 130; --------------------------------------------- 131; Extension Instruction Exception Handler 132; --------------------------------------------- 133ENTRY(EV_Extension) 134 135 EXCEPTION_PROLOGUE 136 137 bl do_extension_fault 138 b ret_from_exception 139END(EV_Extension) 140 141;################ Trap Handling (Syscall, Breakpoint) ################## 142 143; --------------------------------------------- 144; syscall Tracing 145; --------------------------------------------- 146tracesys: 147 ; safekeep EFA (r12) if syscall tracer wanted PC 148 ; for traps, ERET is pre-commit so points to next-PC 149 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11 150 st r12, [r11, THREAD_FAULT_ADDR] ; thread.fault_address 151 152 ; PRE syscall trace hook 153 mov r0, sp ; pt_regs 154 bl @syscall_trace_enter 155 156 ; Tracing code now returns the syscall num (orig or modif) 157 mov r8, r0 158 159 ; Do the Sys Call as we normally would. 160 cmp r8, NR_syscalls - 1 161 mov.hi r0, -ENOSYS 162 bhi tracesys_exit 163 164 ; Restore the sys-call args. Mere invocation of the hook abv could have 165 ; clobbered them (since they are in scratch regs). The tracer could also 166 ; have deliberately changed the syscall args: r0-r7 167 ld r0, [sp, PT_r0] 168 ld r1, [sp, PT_r1] 169 ld r2, [sp, PT_r2] 170 ld r3, [sp, PT_r3] 171 ld r4, [sp, PT_r4] 172 ld r5, [sp, PT_r5] 173 ld r6, [sp, PT_r6] 174 ld r7, [sp, PT_r7] 175 ld.as r9, [sys_call_table, r8] 176 jl [r9] 177 178tracesys_exit: 179 st r0, [sp, PT_r0] 180 181 ; POST syscall trace hook 182 mov r0, sp ; pt_regs needed 183 bl @syscall_trace_exit 184 185 ; don't call ret_from_system_call as it saves r0, already done above 186 b ret_from_exception 187 188; --------------------------------------------- 189; Breakpoint TRAP 190; --------------------------------------------- 191trap_with_param: 192 mov r0, r12 ; EFA in case ptracer/gdb wants stop_pc 193 mov r1, sp ; pt_regs 194 195 ; save callee regs in case tracer/gdb wants to peek 196 SAVE_CALLEE_SAVED_USER 197 198 ; safekeep ref to callee regs 199 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 200 st sp, [r10, THREAD_CALLEE_REG] 201 202 ; call the non syscall trap handler 203 bl do_non_swi_trap 204 205 ; unwind stack to discard callee regs 206 DISCARD_CALLEE_SAVED_USER 207 208 b ret_from_exception 209 210; --------------------------------------------- 211; syscall TRAP 212; ABI: (r0-r7) up to 8 args, (r8) syscall number 213; --------------------------------------------- 214 215ENTRY(EV_Trap) 216 217 EXCEPTION_PROLOGUE_KEEP_AE 218 219 lr r12, [efa] 220 221 FAKE_RET_FROM_EXCPN 222 223 ;============ TRAP N : breakpoints, kprobes etc 224 bmsk.f 0, r10, 7 225 bnz trap_with_param 226 227 ;============ TRAP 0 (no param): syscall 228 229 ; syscall tracing ongoing, invoke pre-post-hooks around syscall 230 GET_CURR_THR_INFO_FLAGS r10 231 and.f 0, r10, _TIF_SYSCALL_WORK 232 bnz tracesys ; this never comes back 233 234 ;============ Normal syscall case 235 236 cmp r8, NR_syscalls - 1 237 mov.hi r0, -ENOSYS 238 bhi .Lret_from_system_call 239 240 ld.as r9,[sys_call_table, r8] 241 jl [r9] 242 243.Lret_from_system_call: 244 st r0, [sp, PT_r0] ; sys call return value in pt_regs 245 246 ; fall through to ret_from_exception 247END(EV_Trap) 248 249;############# Return from Intr/Excp/Trap (Linux Specifics) ############## 250; 251; If ret to user mode do we need to handle signals, schedule() et al. 252 253ENTRY(ret_from_exception) 254 255 ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32 256 ld r8, [sp, PT_status32] ; returning to User/Kernel Mode 257 258 bbit0 r8, STATUS_U_BIT, resume_kernel_mode 259 260 ; Before returning to User mode check-for-and-complete any pending work 261 ; such as rescheduling/signal-delivery etc. 262resume_user_mode_begin: 263 264 ; Disable IRQs to ensures that chk for pending work itself is atomic 265 ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an 266 ; interim IRQ). 267 IRQ_DISABLE r10 268 269 ; Fast Path return to user mode if no pending work 270 GET_CURR_THR_INFO_FLAGS r9 271 and.f 0, r9, _TIF_WORK_MASK 272 bz .Lrestore_regs 273 274 ; --- (Slow Path #1) task preemption --- 275 bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals 276 mov blink, resume_user_mode_begin ; tail-call to U mode ret chks 277 j @schedule ; BTST+Bnz causes relo error in link 278 279.Lchk_pend_signals: 280 IRQ_ENABLE r10 281 282 ; --- (Slow Path #2) pending signal --- 283 mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume() 284 285 GET_CURR_THR_INFO_FLAGS r9 286 and.f 0, r9, _TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL 287 bz .Lchk_notify_resume 288 289 ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs 290 ; in pt_reg since the "C" ABI (kernel code) will automatically 291 ; save/restore callee-saved regs. 292 ; 293 ; However, here we need to explicitly save callee regs because 294 ; (i) If this signal causes coredump - full regfile needed 295 ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus 296 ; tracer might call PEEKUSR(CALLEE reg) 297 ; 298 ; NOTE: SP will grow up by size of CALLEE Reg-File 299 SAVE_CALLEE_SAVED_USER 300 301 ; save location of saved Callee Regs @ thread_struct->callee 302 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 303 st sp, [r10, THREAD_CALLEE_REG] 304 305 bl @do_signal 306 307 ; Ideally we want to discard the Callee reg above, however if this was 308 ; a tracing signal, tracer could have done a POKEUSR(CALLEE reg) 309 RESTORE_CALLEE_SAVED_USER 310 311 b resume_user_mode_begin ; loop back to start of U mode ret 312 313 ; --- (Slow Path #3) notify_resume --- 314.Lchk_notify_resume: 315 btst r9, TIF_NOTIFY_RESUME 316 blnz @do_notify_resume 317 b resume_user_mode_begin ; unconditionally back to U mode ret chks 318 ; for single exit point from this block 319 320resume_kernel_mode: 321 322 ; Disable Interrupts from this point on 323 ; CONFIG_PREEMPTION: This is a must for preempt_schedule_irq() 324 ; !CONFIG_PREEMPTION: To ensure restore_regs is intr safe 325 IRQ_DISABLE r9 326 327#ifdef CONFIG_PREEMPTION 328 329 ; Can't preempt if preemption disabled 330 GET_CURR_THR_INFO_FROM_SP r10 331 ld r8, [r10, THREAD_INFO_PREEMPT_COUNT] 332 brne r8, 0, .Lrestore_regs 333 334 ; check if this task's NEED_RESCHED flag set 335 ld r9, [r10, THREAD_INFO_FLAGS] 336 bbit0 r9, TIF_NEED_RESCHED, .Lrestore_regs 337 338 ; Invoke PREEMPTION 339 jl preempt_schedule_irq 340 341 ; preempt_schedule_irq() always returns with IRQ disabled 342#endif 343 344 b .Lrestore_regs 345 346##### DONT ADD CODE HERE - .Lrestore_regs actually follows in entry-<isa>.S 347 348