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9d42c84f VG |
1 | /* |
2 | * Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARC | |
3 | * | |
4 | * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
2e651ea1 VG |
10 | * vineetg: May 2011 |
11 | * -Userspace unaligned access emulation | |
12 | * | |
547f1125 VG |
13 | * vineetg: Feb 2011 (ptrace low level code fixes) |
14 | * -traced syscall return code (r0) was not saved into pt_regs for restoring | |
15 | * into user reg-file when traded task rets to user space. | |
16 | * -syscalls needing arch-wrappers (mainly for passing sp as pt_regs) | |
17 | * were not invoking post-syscall trace hook (jumping directly into | |
18 | * ret_from_system_call) | |
19 | * | |
9d42c84f VG |
20 | * vineetg: Nov 2010: |
21 | * -Vector table jumps (@8 bytes) converted into branches (@4 bytes) | |
22 | * -To maintain the slot size of 8 bytes/vector, added nop, which is | |
23 | * not executed at runtime. | |
24 | * | |
25 | * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK) | |
26 | * -do_signal()invoked upon TIF_RESTORE_SIGMASK as well | |
27 | * -Wrappers for sys_{,rt_}sigsuspend() nolonger needed as they don't | |
28 | * need ptregs anymore | |
29 | * | |
30 | * Vineetg: Oct 2009 | |
31 | * -In a rare scenario, Process gets a Priv-V exception and gets scheduled | |
32 | * out. Since we don't do FAKE RTIE for Priv-V, CPU excpetion state remains | |
33 | * active (AE bit enabled). This causes a double fault for a subseq valid | |
34 | * exception. Thus FAKE RTIE needed in low level Priv-Violation handler. | |
35 | * Instr Error could also cause similar scenario, so same there as well. | |
36 | * | |
4788a594 VG |
37 | * Vineetg: March 2009 (Supporting 2 levels of Interrupts) |
38 | * | |
9d42c84f VG |
39 | * Vineetg: Aug 28th 2008: Bug #94984 |
40 | * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap | |
41 | * Normally CPU does this automatically, however when doing FAKE rtie, | |
42 | * we need to explicitly do this. The problem in macros | |
43 | * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit | |
44 | * was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit, | |
45 | * setting it and not clearing it clears ZOL context | |
46 | * | |
080c3747 VG |
47 | * Vineetg: May 16th, 2008 |
48 | * - r25 now contains the Current Task when in kernel | |
49 | * | |
9d42c84f VG |
50 | * Vineetg: Dec 22, 2007 |
51 | * Minor Surgery of Low Level ISR to make it SMP safe | |
52 | * - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR | |
53 | * - _current_task is made an array of NR_CPUS | |
54 | * - Access of _current_task wrapped inside a macro so that if hardware | |
55 | * team agrees for a dedicated reg, no other code is touched | |
56 | * | |
57 | * Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004 | |
58 | */ | |
59 | ||
60 | /*------------------------------------------------------------------ | |
61 | * Function ABI | |
62 | *------------------------------------------------------------------ | |
63 | * | |
64 | * Arguments r0 - r7 | |
65 | * Caller Saved Registers r0 - r12 | |
66 | * Callee Saved Registers r13- r25 | |
67 | * Global Pointer (gp) r26 | |
68 | * Frame Pointer (fp) r27 | |
69 | * Stack Pointer (sp) r28 | |
70 | * Interrupt link register (ilink1) r29 | |
71 | * Interrupt link register (ilink2) r30 | |
72 | * Branch link register (blink) r31 | |
73 | *------------------------------------------------------------------ | |
74 | */ | |
75 | ||
76 | .cpu A7 | |
77 | ||
78 | ;############################ Vector Table ################################# | |
79 | ||
80 | .macro VECTOR lbl | |
81 | #if 1 /* Just in case, build breaks */ | |
82 | j \lbl | |
83 | #else | |
84 | b \lbl | |
85 | nop | |
86 | #endif | |
87 | .endm | |
88 | ||
89 | .section .vector, "ax",@progbits | |
90 | .align 4 | |
91 | ||
92 | /* Each entry in the vector table must occupy 2 words. Since it is a jump | |
93 | * across sections (.vector to .text) we are gauranteed that 'j somewhere' | |
94 | * will use the 'j limm' form of the intrsuction as long as somewhere is in | |
95 | * a section other than .vector. | |
96 | */ | |
97 | ||
98 | ; ********* Critical System Events ********************** | |
99 | VECTOR res_service ; 0x0, Restart Vector (0x0) | |
100 | VECTOR mem_service ; 0x8, Mem exception (0x1) | |
101 | VECTOR instr_service ; 0x10, Instrn Error (0x2) | |
102 | ||
103 | ; ******************** Device ISRs ********************** | |
4788a594 VG |
104 | #ifdef CONFIG_ARC_IRQ3_LV2 |
105 | VECTOR handle_interrupt_level2 | |
106 | #else | |
9d42c84f | 107 | VECTOR handle_interrupt_level1 |
4788a594 | 108 | #endif |
9d42c84f VG |
109 | |
110 | VECTOR handle_interrupt_level1 | |
111 | ||
4788a594 VG |
112 | #ifdef CONFIG_ARC_IRQ5_LV2 |
113 | VECTOR handle_interrupt_level2 | |
114 | #else | |
9d42c84f | 115 | VECTOR handle_interrupt_level1 |
4788a594 | 116 | #endif |
9d42c84f | 117 | |
4788a594 VG |
118 | #ifdef CONFIG_ARC_IRQ6_LV2 |
119 | VECTOR handle_interrupt_level2 | |
120 | #else | |
9d42c84f | 121 | VECTOR handle_interrupt_level1 |
4788a594 | 122 | #endif |
9d42c84f VG |
123 | |
124 | .rept 25 | |
125 | VECTOR handle_interrupt_level1 ; Other devices | |
126 | .endr | |
127 | ||
128 | /* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */ | |
129 | ||
130 | ; ******************** Exceptions ********************** | |
131 | VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20) | |
132 | VECTOR EV_TLBMissI ; 0x108, Intruction TLB miss (0x21) | |
133 | VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22) | |
134 | VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23) | |
135 | ; or Misaligned Access | |
136 | VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24) | |
137 | VECTOR EV_Trap ; 0x128, Trap exception (0x25) | |
138 | VECTOR EV_Extension ; 0x130, Extn Intruction Excp (0x26) | |
139 | ||
140 | .rept 24 | |
141 | VECTOR reserved ; Reserved Exceptions | |
142 | .endr | |
143 | ||
144 | #include <linux/linkage.h> /* ARC_{EXTRY,EXIT} */ | |
145 | #include <asm/entry.h> /* SAVE_ALL_{INT1,INT2,TRAP...} */ | |
146 | #include <asm/errno.h> | |
147 | #include <asm/arcregs.h> | |
148 | #include <asm/irqflags.h> | |
149 | ||
150 | ;##################### Scratch Mem for IRQ stack switching ############# | |
151 | ||
8b5850f8 | 152 | ARCFP_DATA int1_saved_reg |
9d42c84f VG |
153 | .align 32 |
154 | .type int1_saved_reg, @object | |
155 | .size int1_saved_reg, 4 | |
156 | int1_saved_reg: | |
157 | .zero 4 | |
158 | ||
4788a594 VG |
159 | /* Each Interrupt level needs it's own scratch */ |
160 | #ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS | |
161 | ||
8b5850f8 | 162 | ARCFP_DATA int2_saved_reg |
4788a594 VG |
163 | .type int2_saved_reg, @object |
164 | .size int2_saved_reg, 4 | |
165 | int2_saved_reg: | |
166 | .zero 4 | |
167 | ||
168 | #endif | |
169 | ||
9d42c84f VG |
170 | ; --------------------------------------------- |
171 | .section .text, "ax",@progbits | |
172 | ||
173 | res_service: ; processor restart | |
174 | flag 0x1 ; not implemented | |
175 | nop | |
176 | nop | |
177 | ||
178 | reserved: ; processor restart | |
179 | rtie ; jump to processor initializations | |
180 | ||
181 | ;##################### Interrupt Handling ############################## | |
182 | ||
4788a594 VG |
183 | #ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS |
184 | ; --------------------------------------------- | |
185 | ; Level 2 ISR: Can interrupt a Level 1 ISR | |
186 | ; --------------------------------------------- | |
187 | ARC_ENTRY handle_interrupt_level2 | |
188 | ||
189 | ; TODO-vineetg for SMP this wont work | |
190 | ; free up r9 as scratchpad | |
191 | st r9, [@int2_saved_reg] | |
192 | ||
193 | ;Which mode (user/kernel) was the system in when intr occured | |
194 | lr r9, [status32_l2] | |
195 | ||
196 | SWITCH_TO_KERNEL_STK | |
197 | SAVE_ALL_INT2 | |
198 | ||
199 | ;------------------------------------------------------ | |
200 | ; if L2 IRQ interrupted a L1 ISR, disable preemption | |
201 | ;------------------------------------------------------ | |
202 | ||
203 | ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs) | |
204 | bbit0 r9, STATUS_A1_BIT, 1f ; L1 not active when L2 IRQ, so normal | |
205 | ||
206 | ; A1 is set in status32_l2 | |
207 | ; bump thread_info->preempt_count (Disable preemption) | |
208 | GET_CURR_THR_INFO_FROM_SP r10 | |
209 | ld r9, [r10, THREAD_INFO_PREEMPT_COUNT] | |
210 | add r9, r9, 1 | |
211 | st r9, [r10, THREAD_INFO_PREEMPT_COUNT] | |
212 | ||
213 | 1: | |
214 | ;------------------------------------------------------ | |
215 | ; setup params for Linux common ISR and invoke it | |
216 | ;------------------------------------------------------ | |
217 | lr r0, [icause2] | |
218 | and r0, r0, 0x1f | |
219 | ||
220 | bl.d @arch_do_IRQ | |
221 | mov r1, sp | |
222 | ||
223 | mov r8,0x2 | |
224 | sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg | |
225 | ||
226 | b ret_from_exception | |
227 | ||
228 | ARC_EXIT handle_interrupt_level2 | |
229 | ||
230 | #endif | |
231 | ||
9d42c84f VG |
232 | ; --------------------------------------------- |
233 | ; Level 1 ISR | |
234 | ; --------------------------------------------- | |
235 | ARC_ENTRY handle_interrupt_level1 | |
236 | ||
237 | /* free up r9 as scratchpad */ | |
41195d23 VG |
238 | #ifdef CONFIG_SMP |
239 | sr r9, [ARC_REG_SCRATCH_DATA0] | |
240 | #else | |
9d42c84f | 241 | st r9, [@int1_saved_reg] |
41195d23 | 242 | #endif |
9d42c84f VG |
243 | |
244 | ;Which mode (user/kernel) was the system in when intr occured | |
245 | lr r9, [status32_l1] | |
246 | ||
247 | SWITCH_TO_KERNEL_STK | |
248 | SAVE_ALL_INT1 | |
249 | ||
250 | lr r0, [icause1] | |
251 | and r0, r0, 0x1f | |
252 | ||
253 | bl.d @arch_do_IRQ | |
254 | mov r1, sp | |
255 | ||
256 | mov r8,0x1 | |
257 | sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg | |
258 | ||
259 | b ret_from_exception | |
260 | ARC_EXIT handle_interrupt_level1 | |
261 | ||
262 | ;################### Non TLB Exception Handling ############################# | |
263 | ||
264 | ; --------------------------------------------- | |
265 | ; Instruction Error Exception Handler | |
266 | ; --------------------------------------------- | |
267 | ||
268 | ARC_ENTRY instr_service | |
269 | ||
270 | EXCPN_PROLOG_FREEUP_REG r9 | |
271 | ||
272 | lr r9, [erstatus] | |
273 | ||
274 | SWITCH_TO_KERNEL_STK | |
275 | SAVE_ALL_SYS | |
276 | ||
277 | lr r0, [ecr] | |
278 | lr r1, [efa] | |
279 | ||
280 | mov r2, sp | |
281 | ||
282 | FAKE_RET_FROM_EXCPN r9 | |
283 | ||
284 | bl do_insterror_or_kprobe | |
285 | b ret_from_exception | |
286 | ARC_EXIT instr_service | |
287 | ||
288 | ; --------------------------------------------- | |
289 | ; Memory Error Exception Handler | |
290 | ; --------------------------------------------- | |
291 | ||
292 | ARC_ENTRY mem_service | |
293 | ||
294 | EXCPN_PROLOG_FREEUP_REG r9 | |
295 | ||
296 | lr r9, [erstatus] | |
297 | ||
298 | SWITCH_TO_KERNEL_STK | |
299 | SAVE_ALL_SYS | |
300 | ||
301 | lr r0, [ecr] | |
302 | lr r1, [efa] | |
303 | mov r2, sp | |
304 | bl do_memory_error | |
305 | b ret_from_exception | |
306 | ARC_EXIT mem_service | |
307 | ||
308 | ; --------------------------------------------- | |
309 | ; Machine Check Exception Handler | |
310 | ; --------------------------------------------- | |
311 | ||
312 | ARC_ENTRY EV_MachineCheck | |
313 | ||
314 | EXCPN_PROLOG_FREEUP_REG r9 | |
315 | lr r9, [erstatus] | |
316 | ||
317 | SWITCH_TO_KERNEL_STK | |
318 | SAVE_ALL_SYS | |
319 | ||
320 | lr r0, [ecr] | |
321 | lr r1, [efa] | |
322 | mov r2, sp | |
323 | ||
324 | brne r0, 0x200100, 1f | |
325 | bl do_tlb_overlap_fault | |
326 | b ret_from_exception | |
327 | ||
328 | 1: | |
329 | ; DEAD END: can't do much, display Regs and HALT | |
330 | SAVE_CALLEE_SAVED_USER | |
331 | ||
332 | GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 | |
333 | st sp, [r10, THREAD_CALLEE_REG] | |
334 | ||
335 | j do_machine_check_fault | |
336 | ||
337 | ARC_EXIT EV_MachineCheck | |
338 | ||
339 | ; --------------------------------------------- | |
340 | ; Protection Violation Exception Handler | |
341 | ; --------------------------------------------- | |
342 | ||
343 | ARC_ENTRY EV_TLBProtV | |
344 | ||
345 | EXCPN_PROLOG_FREEUP_REG r9 | |
346 | ||
347 | ;Which mode (user/kernel) was the system in when Exception occured | |
348 | lr r9, [erstatus] | |
349 | ||
350 | SWITCH_TO_KERNEL_STK | |
351 | SAVE_ALL_SYS | |
352 | ||
353 | ;---------(3) Save some more regs----------------- | |
354 | ; vineetg: Mar 6th: Random Seg Fault issue #1 | |
355 | ; ecr and efa were not saved in case an Intr sneaks in | |
356 | ; after fake rtie | |
357 | ; | |
358 | lr r3, [ecr] | |
359 | lr r4, [efa] | |
360 | ||
361 | ; --------(4) Return from CPU Exception Mode --------- | |
362 | ; Fake a rtie, but rtie to next label | |
363 | ; That way, subsequently, do_page_fault ( ) executes in pure kernel | |
364 | ; mode with further Exceptions enabled | |
365 | ||
366 | FAKE_RET_FROM_EXCPN r9 | |
367 | ||
368 | ;------ (5) Type of Protection Violation? ---------- | |
369 | ; | |
370 | ; ProtV Hardware Exception is triggered for Access Faults of 2 types | |
371 | ; -Access Violaton (WRITE to READ ONLY Page) - for linux COW | |
372 | ; -Unaligned Access (READ/WRITE on odd boundary) | |
373 | ; | |
374 | cmp r3, 0x230400 ; Misaligned data access ? | |
375 | beq 4f | |
376 | ||
377 | ;========= (6a) Access Violation Processing ======== | |
378 | cmp r3, 0x230100 | |
379 | mov r1, 0x0 ; if LD exception ? write = 0 | |
380 | mov.ne r1, 0x1 ; else write = 1 | |
381 | ||
382 | mov r2, r4 ; faulting address | |
383 | mov r0, sp ; pt_regs | |
384 | bl do_page_fault | |
385 | b ret_from_exception | |
386 | ||
387 | ;========== (6b) Non aligned access ============ | |
388 | 4: | |
389 | mov r0, r3 ; cause code | |
390 | mov r1, r4 ; faulting address | |
391 | mov r2, sp ; pt_regs | |
392 | ||
2e651ea1 VG |
393 | #ifdef CONFIG_ARC_MISALIGN_ACCESS |
394 | SAVE_CALLEE_SAVED_USER | |
395 | mov r3, sp ; callee_regs | |
396 | #endif | |
397 | ||
9d42c84f | 398 | bl do_misaligned_access |
2e651ea1 VG |
399 | |
400 | #ifdef CONFIG_ARC_MISALIGN_ACCESS | |
401 | DISCARD_CALLEE_SAVED_USER | |
402 | #endif | |
403 | ||
9d42c84f VG |
404 | b ret_from_exception |
405 | ||
406 | ARC_EXIT EV_TLBProtV | |
407 | ||
408 | ; --------------------------------------------- | |
409 | ; Privilege Violation Exception Handler | |
410 | ; --------------------------------------------- | |
411 | ARC_ENTRY EV_PrivilegeV | |
412 | ||
413 | EXCPN_PROLOG_FREEUP_REG r9 | |
414 | ||
415 | lr r9, [erstatus] | |
416 | ||
417 | SWITCH_TO_KERNEL_STK | |
418 | SAVE_ALL_SYS | |
419 | ||
420 | lr r0, [ecr] | |
421 | lr r1, [efa] | |
422 | mov r2, sp | |
423 | ||
424 | FAKE_RET_FROM_EXCPN r9 | |
425 | ||
426 | bl do_privilege_fault | |
427 | b ret_from_exception | |
428 | ARC_EXIT EV_PrivilegeV | |
429 | ||
430 | ; --------------------------------------------- | |
431 | ; Extension Instruction Exception Handler | |
432 | ; --------------------------------------------- | |
433 | ARC_ENTRY EV_Extension | |
434 | ||
435 | EXCPN_PROLOG_FREEUP_REG r9 | |
436 | lr r9, [erstatus] | |
437 | ||
438 | SWITCH_TO_KERNEL_STK | |
439 | SAVE_ALL_SYS | |
440 | ||
441 | lr r0, [ecr] | |
442 | lr r1, [efa] | |
443 | mov r2, sp | |
444 | bl do_extension_fault | |
445 | b ret_from_exception | |
446 | ARC_EXIT EV_Extension | |
447 | ||
547f1125 VG |
448 | ;######################### System Call Tracing ######################### |
449 | ||
450 | tracesys: | |
451 | ; save EFA in case tracer wants the PC of traced task | |
452 | ; using ERET won't work since next-PC has already committed | |
453 | lr r12, [efa] | |
454 | GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11 | |
455 | st r12, [r11, THREAD_FAULT_ADDR] | |
456 | ||
457 | ; PRE Sys Call Ptrace hook | |
458 | mov r0, sp ; pt_regs needed | |
459 | bl @syscall_trace_entry | |
460 | ||
461 | ; Tracing code now returns the syscall num (orig or modif) | |
462 | mov r8, r0 | |
463 | ||
464 | ; Do the Sys Call as we normally would. | |
465 | ; Validate the Sys Call number | |
466 | cmp r8, NR_syscalls | |
467 | mov.hi r0, -ENOSYS | |
468 | bhi tracesys_exit | |
469 | ||
470 | ; Restore the sys-call args. Mere invocation of the hook abv could have | |
471 | ; clobbered them (since they are in scratch regs). The tracer could also | |
472 | ; have deliberately changed the syscall args: r0-r7 | |
473 | ld r0, [sp, PT_r0] | |
474 | ld r1, [sp, PT_r1] | |
475 | ld r2, [sp, PT_r2] | |
476 | ld r3, [sp, PT_r3] | |
477 | ld r4, [sp, PT_r4] | |
478 | ld r5, [sp, PT_r5] | |
479 | ld r6, [sp, PT_r6] | |
480 | ld r7, [sp, PT_r7] | |
481 | ld.as r9, [sys_call_table, r8] | |
482 | jl [r9] ; Entry into Sys Call Handler | |
483 | ||
484 | tracesys_exit: | |
485 | st r0, [sp, PT_r0] ; sys call return value in pt_regs | |
486 | ||
487 | ;POST Sys Call Ptrace Hook | |
488 | bl @syscall_trace_exit | |
489 | b ret_from_exception ; NOT ret_from_system_call at is saves r0 which | |
490 | ; we'd done before calling post hook above | |
491 | ||
9d42c84f VG |
492 | ;################### Break Point TRAP ########################## |
493 | ||
494 | ; ======= (5b) Trap is due to Break-Point ========= | |
495 | ||
496 | trap_with_param: | |
497 | ||
5c39c0ab | 498 | ; stop_pc info by gdb needs this info |
3eb3e7dd | 499 | stw orig_r8_IS_BRKPT, [sp, PT_orig_r8] |
9d42c84f VG |
500 | |
501 | mov r0, r12 | |
502 | lr r1, [efa] | |
503 | mov r2, sp | |
504 | ||
505 | ; Now that we have read EFA, its safe to do "fake" rtie | |
506 | ; and get out of CPU exception mode | |
507 | FAKE_RET_FROM_EXCPN r11 | |
508 | ||
509 | ; Save callee regs in case gdb wants to have a look | |
510 | ; SP will grow up by size of CALLEE Reg-File | |
511 | ; NOTE: clobbers r12 | |
512 | SAVE_CALLEE_SAVED_USER | |
513 | ||
514 | ; save location of saved Callee Regs @ thread_struct->pc | |
515 | GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 | |
516 | st sp, [r10, THREAD_CALLEE_REG] | |
517 | ||
518 | ; Call the trap handler | |
519 | bl do_non_swi_trap | |
520 | ||
521 | ; unwind stack to discard Callee saved Regs | |
522 | DISCARD_CALLEE_SAVED_USER | |
523 | ||
524 | b ret_from_exception | |
525 | ||
526 | ;##################### Trap Handling ############################## | |
527 | ; | |
528 | ; EV_Trap caused by TRAP_S and TRAP0 instructions. | |
529 | ;------------------------------------------------------------------ | |
530 | ; (1) System Calls | |
531 | ; :parameters in r0-r7. | |
532 | ; :r8 has the system call number | |
533 | ; (2) Break Points | |
534 | ;------------------------------------------------------------------ | |
535 | ||
536 | ARC_ENTRY EV_Trap | |
537 | ||
538 | ; Need at least 1 reg to code the early exception prolog | |
539 | EXCPN_PROLOG_FREEUP_REG r9 | |
540 | ||
541 | ;Which mode (user/kernel) was the system in when intr occured | |
542 | lr r9, [erstatus] | |
543 | ||
544 | SWITCH_TO_KERNEL_STK | |
545 | SAVE_ALL_TRAP | |
546 | ||
547 | ;------- (4) What caused the Trap -------------- | |
548 | lr r12, [ecr] | |
549 | and.f 0, r12, ECR_PARAM_MASK | |
550 | bnz trap_with_param | |
551 | ||
552 | ; ======= (5a) Trap is due to System Call ======== | |
553 | ||
554 | ; Before doing anything, return from CPU Exception Mode | |
555 | FAKE_RET_FROM_EXCPN r11 | |
556 | ||
547f1125 VG |
557 | ; If syscall tracing ongoing, invoke pre-pos-hooks |
558 | GET_CURR_THR_INFO_FLAGS r10 | |
559 | btst r10, TIF_SYSCALL_TRACE | |
560 | bnz tracesys ; this never comes back | |
561 | ||
9d42c84f VG |
562 | ;============ This is normal System Call case ========== |
563 | ; Sys-call num shd not exceed the total system calls avail | |
564 | cmp r8, NR_syscalls | |
565 | mov.hi r0, -ENOSYS | |
566 | bhi ret_from_system_call | |
567 | ||
568 | ; Offset into the syscall_table and call handler | |
569 | ld.as r9,[sys_call_table, r8] | |
570 | jl [r9] ; Entry into Sys Call Handler | |
571 | ||
572 | ; fall through to ret_from_system_call | |
573 | ARC_EXIT EV_Trap | |
574 | ||
575 | ARC_ENTRY ret_from_system_call | |
576 | ||
577 | st r0, [sp, PT_r0] ; sys call return value in pt_regs | |
578 | ||
579 | ; fall through yet again to ret_from_exception | |
580 | ||
581 | ;############# Return from Intr/Excp/Trap (Linux Specifics) ############## | |
582 | ; | |
583 | ; If ret to user mode do we need to handle signals, schedule() et al. | |
584 | ||
585 | ARC_ENTRY ret_from_exception | |
586 | ||
587 | ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32 | |
588 | ld r8, [sp, PT_status32] ; returning to User/Kernel Mode | |
589 | ||
590 | #ifdef CONFIG_PREEMPT | |
591 | bbit0 r8, STATUS_U_BIT, resume_kernel_mode | |
592 | #else | |
593 | bbit0 r8, STATUS_U_BIT, restore_regs | |
594 | #endif | |
595 | ||
596 | ; Before returning to User mode check-for-and-complete any pending work | |
597 | ; such as rescheduling/signal-delivery etc. | |
598 | resume_user_mode_begin: | |
599 | ||
600 | ; Disable IRQs to ensures that chk for pending work itself is atomic | |
601 | ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an | |
602 | ; interim IRQ). | |
603 | IRQ_DISABLE r10 | |
604 | ||
605 | ; Fast Path return to user mode if no pending work | |
606 | GET_CURR_THR_INFO_FLAGS r9 | |
607 | and.f 0, r9, _TIF_WORK_MASK | |
608 | bz restore_regs | |
609 | ||
610 | ; --- (Slow Path #1) task preemption --- | |
611 | bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals | |
612 | mov blink, resume_user_mode_begin ; tail-call to U mode ret chks | |
613 | b @schedule ; BTST+Bnz causes relo error in link | |
614 | ||
615 | .Lchk_pend_signals: | |
616 | IRQ_ENABLE r10 | |
617 | ||
618 | ; --- (Slow Path #2) pending signal --- | |
619 | mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume() | |
620 | ||
621 | bbit0 r9, TIF_SIGPENDING, .Lchk_notify_resume | |
622 | ||
c3581039 VG |
623 | ; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs |
624 | ; in pt_reg since the "C" ABI (kernel code) will automatically | |
625 | ; save/restore callee-saved regs. | |
626 | ; | |
627 | ; However, here we need to explicitly save callee regs because | |
9d42c84f VG |
628 | ; (i) If this signal causes coredump - full regfile needed |
629 | ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus | |
630 | ; tracer might call PEEKUSR(CALLEE reg) | |
631 | ; | |
632 | ; NOTE: SP will grow up by size of CALLEE Reg-File | |
633 | SAVE_CALLEE_SAVED_USER ; clobbers r12 | |
634 | ||
635 | ; save location of saved Callee Regs @ thread_struct->callee | |
636 | GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10 | |
637 | st sp, [r10, THREAD_CALLEE_REG] | |
638 | ||
639 | bl @do_signal | |
640 | ||
c3581039 VG |
641 | ; Ideally we want to discard the Callee reg above, however if this was |
642 | ; a tracing signal, tracer could have done a POKEUSR(CALLEE reg) | |
643 | RESTORE_CALLEE_SAVED_USER | |
9d42c84f VG |
644 | |
645 | b resume_user_mode_begin ; loop back to start of U mode ret | |
646 | ||
647 | ; --- (Slow Path #3) notify_resume --- | |
648 | .Lchk_notify_resume: | |
649 | btst r9, TIF_NOTIFY_RESUME | |
650 | blnz @do_notify_resume | |
651 | b resume_user_mode_begin ; unconditionally back to U mode ret chks | |
652 | ; for single exit point from this block | |
653 | ||
654 | #ifdef CONFIG_PREEMPT | |
655 | ||
656 | resume_kernel_mode: | |
657 | ||
658 | ; Can't preempt if preemption disabled | |
659 | GET_CURR_THR_INFO_FROM_SP r10 | |
660 | ld r8, [r10, THREAD_INFO_PREEMPT_COUNT] | |
661 | brne r8, 0, restore_regs | |
662 | ||
663 | ; check if this task's NEED_RESCHED flag set | |
664 | ld r9, [r10, THREAD_INFO_FLAGS] | |
665 | bbit0 r9, TIF_NEED_RESCHED, restore_regs | |
666 | ||
667 | IRQ_DISABLE r9 | |
668 | ||
669 | ; Invoke PREEMPTION | |
670 | bl preempt_schedule_irq | |
671 | ||
672 | ; preempt_schedule_irq() always returns with IRQ disabled | |
673 | #endif | |
674 | ||
675 | ; fall through | |
676 | ||
677 | ;############# Return from Intr/Excp/Trap (ARC Specifics) ############## | |
678 | ; | |
679 | ; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap) | |
680 | ; IRQ shd definitely not happen between now and rtie | |
681 | ||
682 | restore_regs : | |
683 | ||
684 | ; Disable Interrupts while restoring reg-file back | |
685 | ; XXX can this be optimised out | |
686 | IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy | |
687 | ||
080c3747 VG |
688 | #ifdef CONFIG_ARC_CURR_IN_REG |
689 | ; Restore User R25 | |
690 | ; Earlier this used to be only for returning to user mode | |
691 | ; However with 2 levels of IRQ this can also happen even if | |
692 | ; in kernel mode | |
693 | ld r9, [sp, PT_sp] | |
694 | brhs r9, VMALLOC_START, 8f | |
695 | RESTORE_USER_R25 | |
696 | 8: | |
697 | #endif | |
698 | ||
9d42c84f VG |
699 | ; Restore REG File. In case multiple Events outstanding, |
700 | ; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None | |
701 | ; Note that we use realtime STATUS32 (not pt_regs->status32) to | |
702 | ; decide that. | |
703 | ||
704 | ; if Returning from Exception | |
705 | bbit0 r10, STATUS_AE_BIT, not_exception | |
706 | RESTORE_ALL_SYS | |
707 | rtie | |
708 | ||
709 | ; Not Exception so maybe Interrupts (Level 1 or 2) | |
710 | ||
711 | not_exception: | |
712 | ||
4788a594 VG |
713 | #ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS |
714 | ||
715 | bbit0 r10, STATUS_A2_BIT, not_level2_interrupt | |
716 | ||
717 | ;------------------------------------------------------------------ | |
718 | ; if L2 IRQ interrupted a L1 ISR, we'd disbaled preemption earlier | |
719 | ; so that sched doesnt move to new task, causing L1 to be delayed | |
720 | ; undeterministically. Now that we've achieved that, lets reset | |
721 | ; things to what they were, before returning from L2 context | |
722 | ;---------------------------------------------------------------- | |
723 | ||
3eb3e7dd | 724 | ldw r9, [sp, PT_orig_r8] ; get orig_r8 to make sure it is |
4788a594 VG |
725 | brne r9, orig_r8_IS_IRQ2, 149f ; infact a L2 ISR ret path |
726 | ||
727 | ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs) | |
728 | bbit0 r9, STATUS_A1_BIT, 149f ; L1 not active when L2 IRQ, so normal | |
729 | ||
730 | ; A1 is set in status32_l2 | |
731 | ; decrement thread_info->preempt_count (re-enable preemption) | |
732 | GET_CURR_THR_INFO_FROM_SP r10 | |
733 | ld r9, [r10, THREAD_INFO_PREEMPT_COUNT] | |
734 | ||
735 | ; paranoid check, given A1 was active when A2 happened, preempt count | |
736 | ; must not be 0 beccause we would have incremented it. | |
737 | ; If this does happen we simply HALT as it means a BUG !!! | |
738 | cmp r9, 0 | |
739 | bnz 2f | |
740 | flag 1 | |
741 | ||
742 | 2: | |
743 | sub r9, r9, 1 | |
744 | st r9, [r10, THREAD_INFO_PREEMPT_COUNT] | |
745 | ||
746 | 149: | |
747 | ;return from level 2 | |
748 | RESTORE_ALL_INT2 | |
749 | debug_marker_l2: | |
750 | rtie | |
751 | ||
752 | not_level2_interrupt: | |
753 | ||
754 | #endif | |
755 | ||
9d42c84f VG |
756 | bbit0 r10, STATUS_A1_BIT, not_level1_interrupt |
757 | ||
758 | ;return from level 1 | |
759 | ||
760 | RESTORE_ALL_INT1 | |
761 | debug_marker_l1: | |
762 | rtie | |
763 | ||
764 | not_level1_interrupt: | |
765 | ||
766 | ;this case is for syscalls or Exceptions (with fake rtie) | |
767 | ||
768 | RESTORE_ALL_SYS | |
769 | debug_marker_syscall: | |
770 | rtie | |
771 | ||
772 | ARC_EXIT ret_from_exception | |
773 | ||
774 | ARC_ENTRY ret_from_fork | |
775 | ; when the forked child comes here from the __switch_to function | |
776 | ; r0 has the last task pointer. | |
777 | ; put last task in scheduler queue | |
bf90e1ea VG |
778 | bl @schedule_tail |
779 | ||
780 | ; If kernel thread, jump to it's entry-point | |
781 | ld r9, [sp, PT_status32] | |
782 | brne r9, 0, 1f | |
783 | ||
784 | jl.d [r14] | |
785 | mov r0, r13 ; arg to payload | |
786 | ||
787 | 1: | |
788 | ; special case of kernel_thread entry point returning back due to | |
789 | ; kernel_execve() - pretend return from syscall to ret to userland | |
790 | b ret_from_exception | |
9d42c84f | 791 | ARC_EXIT ret_from_fork |
4adeefe1 VG |
792 | |
793 | ;################### Special Sys Call Wrappers ########################## | |
794 | ||
4adeefe1 VG |
795 | ARC_ENTRY sys_clone_wrapper |
796 | SAVE_CALLEE_SAVED_USER | |
797 | bl @sys_clone | |
798 | DISCARD_CALLEE_SAVED_USER | |
799 | ||
547f1125 VG |
800 | GET_CURR_THR_INFO_FLAGS r10 |
801 | btst r10, TIF_SYSCALL_TRACE | |
802 | bnz tracesys_exit | |
803 | ||
4adeefe1 VG |
804 | b ret_from_system_call |
805 | ARC_EXIT sys_clone_wrapper | |
854a0d95 VG |
806 | |
807 | #ifdef CONFIG_ARC_DW2_UNWIND | |
808 | ; Workaround for bug 94179 (STAR ): | |
809 | ; Despite -fasynchronous-unwind-tables, linker is not making dwarf2 unwinder | |
810 | ; section (.debug_frame) as loadable. So we force it here. | |
811 | ; This also fixes STAR 9000487933 where the prev-workaround (objcopy --setflag) | |
812 | ; would not work after a clean build due to kernel build system dependencies. | |
813 | .section .debug_frame, "wa",@progbits | |
814 | #endif |