1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * Common Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARC
4 * (included from entry-<isa>.S
6 * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
7 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
10 /*------------------------------------------------------------------
12 *------------------------------------------------------------------
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 *------------------------------------------------------------------
24 ;################### Special Sys Call Wrappers ##########################
26 ENTRY(sys_clone_wrapper)
27 SAVE_CALLEE_SAVED_USER
29 DISCARD_CALLEE_SAVED_USER
31 GET_CURR_THR_INFO_FLAGS r10
32 btst r10, TIF_SYSCALL_TRACE
35 b .Lret_from_system_call
36 END(sys_clone_wrapper)
38 ENTRY(sys_clone3_wrapper)
39 SAVE_CALLEE_SAVED_USER
41 DISCARD_CALLEE_SAVED_USER
43 GET_CURR_THR_INFO_FLAGS r10
44 btst r10, TIF_SYSCALL_TRACE
47 b .Lret_from_system_call
48 END(sys_clone3_wrapper)
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
56 ld r9, [sp, PT_status32]
59 jl.d [r14] ; kernel thread entry point
60 mov r0, r13 ; (see PF_KTHREAD block in copy_thread)
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
73 ;################### Non TLB Exception Handling #############################
75 ; ---------------------------------------------
76 ; Instruction Error Exception Handler
77 ; ---------------------------------------------
88 bl do_insterror_or_kprobe
92 ; ---------------------------------------------
93 ; Machine Check Exception Handler
94 ; ---------------------------------------------
96 ENTRY(EV_MachineCheck)
104 ; hardware auto-disables MMU, re-enable it to allow kernel vaddr
105 ; access for say stack unwinding of modules for crash dumps
107 or r3, r3, MMU_ENABLE
112 brne r3, ECR_C_MCHK_DUP_TLB, 1f
114 bl do_tlb_overlap_fault
118 ; DEAD END: can't do much, display Regs and HALT
119 SAVE_CALLEE_SAVED_USER
121 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10
122 st sp, [r10, THREAD_CALLEE_REG]
124 j do_machine_check_fault
128 ; ---------------------------------------------
129 ; Privilege Violation Exception Handler
130 ; ---------------------------------------------
140 bl do_privilege_fault
144 ; ---------------------------------------------
145 ; Extension Instruction Exception Handler
146 ; ---------------------------------------------
156 bl do_extension_fault
160 ;################ Trap Handling (Syscall, Breakpoint) ##################
162 ; ---------------------------------------------
164 ; ---------------------------------------------
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 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11
169 st r12, [r11, THREAD_FAULT_ADDR] ; thread.fault_address
171 ; PRE Sys Call Ptrace hook
172 mov r0, sp ; pt_regs needed
173 bl @syscall_trace_entry
175 ; Tracing code now returns the syscall num (orig or modif)
178 ; Do the Sys Call as we normally would.
179 ; Validate the Sys Call number
180 cmp r8, NR_syscalls - 1
184 ; Restore the sys-call args. Mere invocation of the hook abv could have
185 ; clobbered them (since they are in scratch regs). The tracer could also
186 ; have deliberately changed the syscall args: r0-r7
195 ld.as r9, [sys_call_table, r8]
196 jl [r9] ; Entry into Sys Call Handler
199 st r0, [sp, PT_r0] ; sys call return value in pt_regs
201 ;POST Sys Call Ptrace Hook
202 mov r0, sp ; pt_regs needed
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
207 ; ---------------------------------------------
209 ; ---------------------------------------------
211 mov r0, r12 ; EFA in case ptracer/gdb wants stop_pc
214 ; Save callee regs in case gdb wants to have a look
215 ; SP will grow up by size of CALLEE Reg-File
217 SAVE_CALLEE_SAVED_USER
219 ; save location of saved Callee Regs @ thread_struct->pc
220 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10
221 st sp, [r10, THREAD_CALLEE_REG]
223 ; Call the trap handler
226 ; unwind stack to discard Callee saved Regs
227 DISCARD_CALLEE_SAVED_USER
231 ; ---------------------------------------------
233 ; ABI: (r0-r7) upto 8 args, (r8) syscall number
234 ; ---------------------------------------------
244 ;============ TRAP 1 :breakpoints
245 ; Check ECR for trap with arg (PROLOGUE ensures r10 has ECR)
249 ;============ TRAP (no param): syscall top level
251 ; If syscall tracing ongoing, invoke pre-post-hooks
252 GET_CURR_THR_INFO_FLAGS r10
253 btst r10, TIF_SYSCALL_TRACE
254 bnz tracesys ; this never comes back
256 ;============ Normal syscall case
258 ; syscall num shd not exceed the total system calls avail
259 cmp r8, NR_syscalls - 1
261 bhi .Lret_from_system_call
263 ; Offset into the syscall_table and call handler
264 ld.as r9,[sys_call_table, r8]
265 jl [r9] ; Entry into Sys Call Handler
267 .Lret_from_system_call:
269 st r0, [sp, PT_r0] ; sys call return value in pt_regs
271 ; fall through to ret_from_exception
274 ;############# Return from Intr/Excp/Trap (Linux Specifics) ##############
276 ; If ret to user mode do we need to handle signals, schedule() et al.
278 ENTRY(ret_from_exception)
280 ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32
281 ld r8, [sp, PT_status32] ; returning to User/Kernel Mode
283 bbit0 r8, STATUS_U_BIT, resume_kernel_mode
285 ; Before returning to User mode check-for-and-complete any pending work
286 ; such as rescheduling/signal-delivery etc.
287 resume_user_mode_begin:
289 ; Disable IRQs to ensures that chk for pending work itself is atomic
290 ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an
294 ; Fast Path return to user mode if no pending work
295 GET_CURR_THR_INFO_FLAGS r9
296 and.f 0, r9, _TIF_WORK_MASK
299 ; --- (Slow Path #1) task preemption ---
300 bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals
301 mov blink, resume_user_mode_begin ; tail-call to U mode ret chks
302 j @schedule ; BTST+Bnz causes relo error in link
307 ; --- (Slow Path #2) pending signal ---
308 mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume()
310 GET_CURR_THR_INFO_FLAGS r9
311 and.f 0, r9, _TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL
312 bz .Lchk_notify_resume
314 ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs
315 ; in pt_reg since the "C" ABI (kernel code) will automatically
316 ; save/restore callee-saved regs.
318 ; However, here we need to explicitly save callee regs because
319 ; (i) If this signal causes coredump - full regfile needed
320 ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus
321 ; tracer might call PEEKUSR(CALLEE reg)
323 ; NOTE: SP will grow up by size of CALLEE Reg-File
324 SAVE_CALLEE_SAVED_USER ; clobbers r12
326 ; save location of saved Callee Regs @ thread_struct->callee
327 GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10
328 st sp, [r10, THREAD_CALLEE_REG]
332 ; Ideally we want to discard the Callee reg above, however if this was
333 ; a tracing signal, tracer could have done a POKEUSR(CALLEE reg)
334 RESTORE_CALLEE_SAVED_USER
336 b resume_user_mode_begin ; loop back to start of U mode ret
338 ; --- (Slow Path #3) notify_resume ---
340 btst r9, TIF_NOTIFY_RESUME
341 blnz @do_notify_resume
342 b resume_user_mode_begin ; unconditionally back to U mode ret chks
343 ; for single exit point from this block
347 ; Disable Interrupts from this point on
348 ; CONFIG_PREEMPTION: This is a must for preempt_schedule_irq()
349 ; !CONFIG_PREEMPTION: To ensure restore_regs is intr safe
352 #ifdef CONFIG_PREEMPTION
354 ; Can't preempt if preemption disabled
355 GET_CURR_THR_INFO_FROM_SP r10
356 ld r8, [r10, THREAD_INFO_PREEMPT_COUNT]
357 brne r8, 0, .Lrestore_regs
359 ; check if this task's NEED_RESCHED flag set
360 ld r9, [r10, THREAD_INFO_FLAGS]
361 bbit0 r9, TIF_NEED_RESCHED, .Lrestore_regs
364 jl preempt_schedule_irq
366 ; preempt_schedule_irq() always returns with IRQ disabled
371 ##### DONT ADD CODE HERE - .Lrestore_regs actually follows in entry-<isa>.S