1/* 2 * Common Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARC 3 * (included from entry-<isa>.S 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 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13/*------------------------------------------------------------------ 14 * Function ABI 15 *------------------------------------------------------------------ 16 * 17 * Arguments r0 - r7 18 * Caller Saved Registers r0 - r12 19 * Callee Saved Registers r13- r25 20 * Global Pointer (gp) r26 21 * Frame Pointer (fp) r27 22 * Stack Pointer (sp) r28 23 * Branch link register (blink) r31 24 *------------------------------------------------------------------ 25 */ 26 27;################### Special Sys Call Wrappers ########################## 28 29ENTRY(sys_clone_wrapper) 30 SAVE_CALLEE_SAVED_USER 31 bl @sys_clone 32 DISCARD_CALLEE_SAVED_USER 33 34 GET_CURR_THR_INFO_FLAGS r10 35 btst r10, TIF_SYSCALL_TRACE 36 bnz tracesys_exit 37 38 b ret_from_system_call 39END(sys_clone_wrapper) 40 41ENTRY(ret_from_fork) 42 ; when the forked child comes here from the __switch_to function 43 ; r0 has the last task pointer. 44 ; put last task in scheduler queue 45 bl @schedule_tail 46 47 ld r9, [sp, PT_status32] 48 brne r9, 0, 1f 49 50 jl.d [r14] ; kernel thread entry point 51 mov r0, r13 ; (see PF_KTHREAD block in copy_thread) 52 531: 54 ; Return to user space 55 ; 1. Any forked task (Reach here via BRne above) 56 ; 2. First ever init task (Reach here via return from JL above) 57 ; This is the historic "kernel_execve" use-case, to return to init 58 ; user mode, in a round about way since that is always done from 59 ; a kernel thread which is executed via JL above but always returns 60 ; out whenever kernel_execve (now inline do_fork()) is involved 61 b ret_from_exception 62END(ret_from_fork) 63 64#ifdef CONFIG_ARC_DW2_UNWIND 65; Workaround for bug 94179 (STAR ): 66; Despite -fasynchronous-unwind-tables, linker is not making dwarf2 unwinder 67; section (.debug_frame) as loadable. So we force it here. 68; This also fixes STAR 9000487933 where the prev-workaround (objcopy --setflag) 69; would not work after a clean build due to kernel build system dependencies. 70.section .debug_frame, "wa",@progbits 71 72; Reset to .text as this file is included in entry-<isa>.S 73.section .text, "ax",@progbits 74#endif 75 76;################### Non TLB Exception Handling ############################# 77 78; --------------------------------------------- 79; Instruction Error Exception Handler 80; --------------------------------------------- 81 82ENTRY(instr_service) 83 84 EXCEPTION_PROLOGUE 85 86 lr r0, [efa] 87 mov r1, sp 88 89 FAKE_RET_FROM_EXCPN 90 91 bl do_insterror_or_kprobe 92 b ret_from_exception 93END(instr_service) 94 95; --------------------------------------------- 96; Memory Error Exception Handler 97; --------------------------------------------- 98 99ENTRY(mem_service) 100 101 EXCEPTION_PROLOGUE 102 103 lr r0, [efa] 104 mov r1, sp 105 106 FAKE_RET_FROM_EXCPN 107 108 bl do_memory_error 109 b ret_from_exception 110END(mem_service) 111 112; --------------------------------------------- 113; Machine Check Exception Handler 114; --------------------------------------------- 115 116ENTRY(EV_MachineCheck) 117 118 EXCEPTION_PROLOGUE 119 120 lr r2, [ecr] 121 lr r0, [efa] 122 mov r1, sp 123 124 lsr r3, r2, 8 125 bmsk r3, r3, 7 126 brne r3, ECR_C_MCHK_DUP_TLB, 1f 127 128 bl do_tlb_overlap_fault 129 b ret_from_exception 130 1311: 132 ; DEAD END: can't do much, display Regs and HALT 133 SAVE_CALLEE_SAVED_USER 134 135 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 136 st sp, [r10, THREAD_CALLEE_REG] 137 138 j do_machine_check_fault 139 140END(EV_MachineCheck) 141 142; --------------------------------------------- 143; Privilege Violation Exception Handler 144; --------------------------------------------- 145ENTRY(EV_PrivilegeV) 146 147 EXCEPTION_PROLOGUE 148 149 lr r0, [efa] 150 mov r1, sp 151 152 FAKE_RET_FROM_EXCPN 153 154 bl do_privilege_fault 155 b ret_from_exception 156END(EV_PrivilegeV) 157 158; --------------------------------------------- 159; Extension Instruction Exception Handler 160; --------------------------------------------- 161ENTRY(EV_Extension) 162 163 EXCEPTION_PROLOGUE 164 165 lr r0, [efa] 166 mov r1, sp 167 168 FAKE_RET_FROM_EXCPN 169 170 bl do_extension_fault 171 b ret_from_exception 172END(EV_Extension) 173 174;################ Trap Handling (Syscall, Breakpoint) ################## 175 176; --------------------------------------------- 177; syscall Tracing 178; --------------------------------------------- 179tracesys: 180 ; save EFA in case tracer wants the PC of traced task 181 ; using ERET won't work since next-PC has already committed 182 lr r12, [efa] 183 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11 184 st r12, [r11, THREAD_FAULT_ADDR] ; thread.fault_address 185 186 ; PRE Sys Call Ptrace hook 187 mov r0, sp ; pt_regs needed 188 bl @syscall_trace_entry 189 190 ; Tracing code now returns the syscall num (orig or modif) 191 mov r8, r0 192 193 ; Do the Sys Call as we normally would. 194 ; Validate the Sys Call number 195 cmp r8, NR_syscalls 196 mov.hi r0, -ENOSYS 197 bhi tracesys_exit 198 199 ; Restore the sys-call args. Mere invocation of the hook abv could have 200 ; clobbered them (since they are in scratch regs). The tracer could also 201 ; have deliberately changed the syscall args: r0-r7 202 ld r0, [sp, PT_r0] 203 ld r1, [sp, PT_r1] 204 ld r2, [sp, PT_r2] 205 ld r3, [sp, PT_r3] 206 ld r4, [sp, PT_r4] 207 ld r5, [sp, PT_r5] 208 ld r6, [sp, PT_r6] 209 ld r7, [sp, PT_r7] 210 ld.as r9, [sys_call_table, r8] 211 jl [r9] ; Entry into Sys Call Handler 212 213tracesys_exit: 214 st r0, [sp, PT_r0] ; sys call return value in pt_regs 215 216 ;POST Sys Call Ptrace Hook 217 bl @syscall_trace_exit 218 b ret_from_exception ; NOT ret_from_system_call at is saves r0 which 219 ; we'd done before calling post hook above 220 221; --------------------------------------------- 222; Breakpoint TRAP 223; --------------------------------------------- 224trap_with_param: 225 226 ; stop_pc info by gdb needs this info 227 lr r0, [efa] 228 mov r1, sp 229 230 ; Now that we have read EFA, it is safe to do "fake" rtie 231 ; and get out of CPU exception mode 232 FAKE_RET_FROM_EXCPN 233 234 ; Save callee regs in case gdb wants to have a look 235 ; SP will grow up by size of CALLEE Reg-File 236 ; NOTE: clobbers r12 237 SAVE_CALLEE_SAVED_USER 238 239 ; save location of saved Callee Regs @ thread_struct->pc 240 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 241 st sp, [r10, THREAD_CALLEE_REG] 242 243 ; Call the trap handler 244 bl do_non_swi_trap 245 246 ; unwind stack to discard Callee saved Regs 247 DISCARD_CALLEE_SAVED_USER 248 249 b ret_from_exception 250 251; --------------------------------------------- 252; syscall TRAP 253; ABI: (r0-r7) upto 8 args, (r8) syscall number 254; --------------------------------------------- 255 256ENTRY(EV_Trap) 257 258 EXCEPTION_PROLOGUE 259 260 ;============ TRAP 1 :breakpoints 261 ; Check ECR for trap with arg (PROLOGUE ensures r9 has ECR) 262 bmsk.f 0, r9, 7 263 bnz trap_with_param 264 265 ;============ TRAP (no param): syscall top level 266 267 ; First return from Exception to pure K mode (Exception/IRQs renabled) 268 FAKE_RET_FROM_EXCPN 269 270 ; If syscall tracing ongoing, invoke pre-post-hooks 271 GET_CURR_THR_INFO_FLAGS r10 272 btst r10, TIF_SYSCALL_TRACE 273 bnz tracesys ; this never comes back 274 275 ;============ Normal syscall case 276 277 ; syscall num shd not exceed the total system calls avail 278 cmp r8, NR_syscalls 279 mov.hi r0, -ENOSYS 280 bhi ret_from_system_call 281 282 ; Offset into the syscall_table and call handler 283 ld.as r9,[sys_call_table, r8] 284 jl [r9] ; Entry into Sys Call Handler 285 286 ; fall through to ret_from_system_call 287END(EV_Trap) 288 289ENTRY(ret_from_system_call) 290 291 st r0, [sp, PT_r0] ; sys call return value in pt_regs 292 293 ; fall through yet again to ret_from_exception 294 295;############# Return from Intr/Excp/Trap (Linux Specifics) ############## 296; 297; If ret to user mode do we need to handle signals, schedule() et al. 298 299ENTRY(ret_from_exception) 300 301 ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32 302 ld r8, [sp, PT_status32] ; returning to User/Kernel Mode 303 304 bbit0 r8, STATUS_U_BIT, resume_kernel_mode 305 306 ; Before returning to User mode check-for-and-complete any pending work 307 ; such as rescheduling/signal-delivery etc. 308resume_user_mode_begin: 309 310 ; Disable IRQs to ensures that chk for pending work itself is atomic 311 ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an 312 ; interim IRQ). 313 IRQ_DISABLE r10 314 315 ; Fast Path return to user mode if no pending work 316 GET_CURR_THR_INFO_FLAGS r9 317 and.f 0, r9, _TIF_WORK_MASK 318 bz .Lrestore_regs 319 320 ; --- (Slow Path #1) task preemption --- 321 bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals 322 mov blink, resume_user_mode_begin ; tail-call to U mode ret chks 323 b @schedule ; BTST+Bnz causes relo error in link 324 325.Lchk_pend_signals: 326 IRQ_ENABLE r10 327 328 ; --- (Slow Path #2) pending signal --- 329 mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume() 330 331 GET_CURR_THR_INFO_FLAGS r9 332 bbit0 r9, TIF_SIGPENDING, .Lchk_notify_resume 333 334 ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs 335 ; in pt_reg since the "C" ABI (kernel code) will automatically 336 ; save/restore callee-saved regs. 337 ; 338 ; However, here we need to explicitly save callee regs because 339 ; (i) If this signal causes coredump - full regfile needed 340 ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus 341 ; tracer might call PEEKUSR(CALLEE reg) 342 ; 343 ; NOTE: SP will grow up by size of CALLEE Reg-File 344 SAVE_CALLEE_SAVED_USER ; clobbers r12 345 346 ; save location of saved Callee Regs @ thread_struct->callee 347 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 348 st sp, [r10, THREAD_CALLEE_REG] 349 350 bl @do_signal 351 352 ; Ideally we want to discard the Callee reg above, however if this was 353 ; a tracing signal, tracer could have done a POKEUSR(CALLEE reg) 354 RESTORE_CALLEE_SAVED_USER 355 356 b resume_user_mode_begin ; loop back to start of U mode ret 357 358 ; --- (Slow Path #3) notify_resume --- 359.Lchk_notify_resume: 360 btst r9, TIF_NOTIFY_RESUME 361 blnz @do_notify_resume 362 b resume_user_mode_begin ; unconditionally back to U mode ret chks 363 ; for single exit point from this block 364 365resume_kernel_mode: 366 367 ; Disable Interrupts from this point on 368 ; CONFIG_PREEMPT: This is a must for preempt_schedule_irq() 369 ; !CONFIG_PREEMPT: To ensure restore_regs is intr safe 370 IRQ_DISABLE r9 371 372#ifdef CONFIG_PREEMPT 373 374 ; Can't preempt if preemption disabled 375 GET_CURR_THR_INFO_FROM_SP r10 376 ld r8, [r10, THREAD_INFO_PREEMPT_COUNT] 377 brne r8, 0, .Lrestore_regs 378 379 ; check if this task's NEED_RESCHED flag set 380 ld r9, [r10, THREAD_INFO_FLAGS] 381 bbit0 r9, TIF_NEED_RESCHED, .Lrestore_regs 382 383 ; Invoke PREEMPTION 384 bl preempt_schedule_irq 385 386 ; preempt_schedule_irq() always returns with IRQ disabled 387#endif 388 389 b .Lrestore_regs 390 391##### DONT ADD CODE HERE - .Lrestore_regs actually follows in entry-<isa>.S 392 393