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