1 /*
2 * linux/arch/nios2/kernel/entry.S
3 *
4 * Copyright (C) 2013-2014 Altera Corporation
5 * Copyright (C) 2009, Wind River Systems Inc
6 *
7 * Implemented by fredrik.markstrom@gmail.com
8 *
9 * Copyright (C) 1999-2002, Greg Ungerer (ger
10 * Copyright (C) 1998 D. Jeff Dionne <jeff@li
11 * Kenneth Albanowski <kja
12 * Copyright (C) 2000 Lineo Inc. (www.lineo.
13 * Copyright (C) 2004 Microtronix Datacom Lt
14 *
15 * This file is subject to the terms and condi
16 * License. See the file "COPYING" in the mai
17 * for more details.
18 *
19 * Linux/m68k support by Hamish Macdonald
20 *
21 * 68060 fixes by Jesper Skov
22 * ColdFire support by Greg Ungerer (gerg@snap
23 * 5307 fixes by David W. Miller
24 * linux 2.4 support David McCullough <davidm@s
25 */
26
27 #include <linux/sys.h>
28 #include <linux/linkage.h>
29 #include <asm/asm-offsets.h>
30 #include <asm/asm-macros.h>
31 #include <asm/thread_info.h>
32 #include <asm/errno.h>
33 #include <asm/setup.h>
34 #include <asm/entry.h>
35 #include <asm/unistd.h>
36 #include <asm/processor.h>
37
38 .macro GET_THREAD_INFO reg
39 .if THREAD_SIZE & 0xffff0000
40 andhi \reg, sp, %hi(~(THREAD_SIZE-1)
41 .else
42 addi \reg, r0, %lo(~(THREAD_SIZE-1)
43 and \reg, \reg, sp
44 .endif
45 .endm
46
47 .macro kuser_cmpxchg_check
48 /*
49 * Make sure our user space atomic hel
50 * interrupted in a critical region.
51 * ea-4 = address of interrupted insn
52 * sp = saved regs.
53 * cmpxchg_ldw = first critical insn,
54 * If ea <= cmpxchg_stw and ea > cmpxc
55 * cmpxchg_ldw + 4.
56 */
57 /* et = cmpxchg_stw + 4 */
58 movui et, (KUSER_BASE + 4 + (cmpxchg
59 bgtu ea, et, 1f
60
61 subi et, et, (cmpxchg_stw - cmpxchg
62 bltu ea, et, 1f
63 stw et, PT_EA(sp) /* fix up EA *
64 mov ea, et
65 1:
66 .endm
67
68 .section .rodata
69 .align 4
70 exception_table:
71 .word unhandled_exception /* 0 -
72 .word unhandled_exception /* 1 -
73 .word external_interrupt /* 2 -
74 .word handle_trap /* 3 -
75
76 .word instruction_trap /* 4 -
77 .word handle_illegal /* 5 -
78 .word handle_unaligned /* 6 -
79 .word handle_unaligned /* 7 -
80
81 .word handle_diverror /* 8 -
82 .word protection_exception_ba /* 9 -
83 .word protection_exception_instr /* 10
84 .word protection_exception_ba /* 11
85
86 .word unhandled_exception /* 12
87 .word protection_exception_pte /* 13
88 .word protection_exception_pte /* 14
89 .word protection_exception_pte /* 15
90
91 .word unhandled_exception /* 16
92
93 trap_table:
94 .word handle_system_call /* 0
95 .word handle_trap_1 /* 1
96 .word handle_trap_2 /* 2
97 .word handle_trap_3 /* 3
98 .word handle_trap_reserved /* 4
99 .word handle_trap_reserved /* 5
100 .word handle_trap_reserved /* 6
101 .word handle_trap_reserved /* 7
102 .word handle_trap_reserved /* 8
103 .word handle_trap_reserved /* 9
104 .word handle_trap_reserved /* 10
105 .word handle_trap_reserved /* 11
106 .word handle_trap_reserved /* 12
107 .word handle_trap_reserved /* 13
108 .word handle_trap_reserved /* 14
109 .word handle_trap_reserved /* 15
110 .word handle_trap_reserved /* 16
111 .word handle_trap_reserved /* 17
112 .word handle_trap_reserved /* 18
113 .word handle_trap_reserved /* 19
114 .word handle_trap_reserved /* 20
115 .word handle_trap_reserved /* 21
116 .word handle_trap_reserved /* 22
117 .word handle_trap_reserved /* 23
118 .word handle_trap_reserved /* 24
119 .word handle_trap_reserved /* 25
120 .word handle_trap_reserved /* 26
121 .word handle_trap_reserved /* 27
122 .word handle_trap_reserved /* 28
123 .word handle_trap_reserved /* 29
124 #ifdef CONFIG_KGDB
125 .word handle_kgdb_breakpoint /* 30
126 #else
127 .word instruction_trap
128 #endif
129 .word handle_breakpoint /* 31
130
131 .text
132 .set noat
133 .set nobreak
134
135 ENTRY(inthandler)
136 SAVE_ALL
137
138 kuser_cmpxchg_check
139
140 /* Clear EH bit before we get a new ex
141 * and after we have saved it to the e
142 * whether it's trap, tlb-miss or inte
143 * estatus is not updated the next exc
144 */
145 rdctl r24, status
146 movi r9, %lo(~STATUS_EH)
147 and r24, r24, r9
148 wrctl status, r24
149
150 /* Read cause and vector and branch to
151 mov r4, sp
152 rdctl r5, exception
153 movia r9, exception_table
154 add r24, r9, r5
155 ldw r24, 0(r24)
156 jmp r24
157
158
159 /*********************************************
160 * Handle traps
161 *********************************************
162 */
163 ENTRY(handle_trap)
164 ldwio r24, -4(ea) /* instruction
165 srli r24, r24, 4
166 andi r24, r24, 0x7c
167 movia r9,trap_table
168 add r24, r24, r9
169 ldw r24, 0(r24)
170 jmp r24
171
172
173 /*********************************************
174 * Handle system calls
175 *********************************************
176 */
177 ENTRY(handle_system_call)
178 /* Enable interrupts */
179 rdctl r10, status
180 ori r10, r10, STATUS_PIE
181 wrctl status, r10
182
183 /* Reload registers destroyed by commo
184 ldw r4, PT_R4(sp)
185 ldw r5, PT_R5(sp)
186
187 local_restart:
188 stw r2, PT_ORIG_R2(sp)
189 /* Check that the requested system cal
190 movui r1, __NR_syscalls
191 bgeu r2, r1, ret_invsyscall
192 slli r1, r2, 2
193 movhi r11, %hiadj(sys_call_table)
194 add r1, r1, r11
195 ldw r1, %lo(sys_call_table)(r1)
196
197 /* Check if we are being traced */
198 GET_THREAD_INFO r11
199 ldw r11,TI_FLAGS(r11)
200 BTBNZ r11,r11,TIF_SYSCALL_TRACE,trac
201
202 /* Execute the system call */
203 callr r1
204
205 /* If the syscall returns a negative r
206 * Set r7 to 1 to indicate error,
207 * Negate r2 to get a positive error
208 * If the syscall returns zero or a po
209 * Set r7 to 0.
210 * The sigreturn system calls will ski
211 * adding to register ra. To avoid des
212 */
213 translate_rc_and_ret:
214 movi r1, 0
215 bge r2, zero, 3f
216 ldw r1, PT_ORIG_R2(sp)
217 addi r1, r1, 1
218 beq r1, zero, 3f
219 sub r2, zero, r2
220 movi r1, 1
221 3:
222 stw r2, PT_R2(sp)
223 stw r1, PT_R7(sp)
224 end_translate_rc_and_ret:
225
226 ret_from_exception:
227 ldw r1, PT_ESTATUS(sp)
228 /* if so, skip resched, signals */
229 TSTBNZ r1, r1, ESTATUS_EU, Luser_retu
230
231 restore_all:
232 rdctl r10, status
233 andi r10, r10, %lo(~STATUS_PIE)
234 wrctl status, r10
235 RESTORE_ALL
236 eret
237
238 /* If the syscall number was invalid r
239 ret_invsyscall:
240 movi r2, -ENOSYS
241 br translate_rc_and_ret
242
243 /* This implements the same as above,
244 * do_syscall_trace_enter and do_sysca
245 * syscall in order for utilities like
246 */
247 traced_system_call:
248 SAVE_SWITCH_STACK
249 call do_syscall_trace_enter
250 RESTORE_SWITCH_STACK
251
252 /* Create system call register argumen
253 arguments on stack are already in p
254 of pt_regs. */
255 ldw r2, PT_R2(sp)
256 ldw r4, PT_R4(sp)
257 ldw r5, PT_R5(sp)
258 ldw r6, PT_R6(sp)
259 ldw r7, PT_R7(sp)
260
261 /* Fetch the syscall function. */
262 movui r1, __NR_syscalls
263 bgeu r2, r1, traced_invsyscall
264 slli r1, r2, 2
265 movhi r11,%hiadj(sys_call_table)
266 add r1, r1, r11
267 ldw r1, %lo(sys_call_table)(r1)
268
269 callr r1
270
271 /* If the syscall returns a negative r
272 * Set r7 to 1 to indicate error,
273 * Negate r2 to get a positive error
274 * If the syscall returns zero or a po
275 * Set r7 to 0.
276 * The sigreturn system calls will ski
277 * adding to register ra. To avoid des
278 */
279 translate_rc_and_ret2:
280 movi r1, 0
281 bge r2, zero, 4f
282 ldw r1, PT_ORIG_R2(sp)
283 addi r1, r1, 1
284 beq r1, zero, 4f
285 sub r2, zero, r2
286 movi r1, 1
287 4:
288 stw r2, PT_R2(sp)
289 stw r1, PT_R7(sp)
290 end_translate_rc_and_ret2:
291 SAVE_SWITCH_STACK
292 call do_syscall_trace_exit
293 RESTORE_SWITCH_STACK
294 br ret_from_exception
295
296 /* If the syscall number was invalid r
297 traced_invsyscall:
298 movi r2, -ENOSYS
299 br translate_rc_and_ret2
300
301 Luser_return:
302 GET_THREAD_INFO r11
303 ldw r10, TI_FLAGS(r11)
304 ANDI32 r11, r10, _TIF_WORK_MASK
305 beq r11, r0, restore_all
306 BTBZ r1, r10, TIF_NEED_RESCHED, Lsi
307
308 /* Reschedule work */
309 call schedule
310 br ret_from_exception
311
312 Lsignal_return:
313 ANDI32 r1, r10, _TIF_SIGPENDING | _TI
314 beq r1, r0, restore_all
315 mov r4, sp /* pt_
316 SAVE_SWITCH_STACK
317 call do_notify_resume
318 beq r2, r0, no_work_pending
319 RESTORE_SWITCH_STACK
320 /* prepare restart syscall here withou
321 ldw r2, PT_R2(sp) /* reload sysc
322 ldw r4, PT_R4(sp) /* reload sysc
323 ldw r5, PT_R5(sp)
324 ldw r6, PT_R6(sp)
325 ldw r7, PT_R7(sp)
326 ldw r8, PT_R8(sp)
327 ldw r9, PT_R9(sp)
328 br local_restart /* restart sys
329
330 no_work_pending:
331 RESTORE_SWITCH_STACK
332 br ret_from_exception
333
334 /*********************************************
335 * Handle external interrupts.
336 *********************************************
337 */
338 /*
339 * This is the generic interrupt handler (for
340 * sources). It figures out the vector number
341 * interrupt service routine directly.
342 */
343 external_interrupt:
344 rdctl r12, ipending
345 rdctl r9, ienable
346 and r12, r12, r9
347 /* skip if no interrupt is pending */
348 beq r12, r0, ret_from_interrupt
349
350 /*
351 * Process an external hardware interr
352 */
353
354 addi ea, ea, -4 /* re-issue th
355 stw ea, PT_EA(sp)
356 2: movi r4, %lo(-1) /* Start from
357 highes
358 /* This is the
359 1: andi r10, r12, 1 /* Isolate bit
360 srli r12, r12, 1 /* shift count
361 multip
362 addi r4, r4, 1
363 beq r10, r0, 1b
364 mov r5, sp /* Setup pt_re
365 call do_IRQ
366 rdctl r12, ipending /* check again
367 rdctl r9, ienable /* Isolate pos
368 and r12, r12, r9
369 bne r12, r0, 2b
370 /* br ret_from_interrupt */ /* fall
371
372 ENTRY(ret_from_interrupt)
373 ldw r1, PT_ESTATUS(sp) /* che
374 TSTBNZ r1, r1, ESTATUS_EU, Luser_retu
375
376 #ifdef CONFIG_PREEMPTION
377 GET_THREAD_INFO r1
378 ldw r4, TI_PREEMPT_COUNT(r1)
379 bne r4, r0, restore_all
380 ldw r4, TI_FLAGS(r1)
381 BTBZ r10, r4, TIF_NEED_RESCHED, res
382 ldw r4, PT_ESTATUS(sp) /* ? I
383 andi r10, r4, ESTATUS_EPIE
384 beq r10, r0, restore_all
385 call preempt_schedule_irq
386 #endif
387 br restore_all
388
389 /*********************************************
390 * A few syscall wrappers
391 *********************************************
392 */
393 /*
394 * int clone(unsigned long clone_flags, unsign
395 * int __user * parent_tidptr, in
396 * int tls_val)
397 */
398 ENTRY(sys_clone)
399 SAVE_SWITCH_STACK
400 subi sp, sp, 4 /* make space for tl
401 stw r8, 0(sp) /* pass tls pointer
402 call nios2_clone
403 addi sp, sp, 4
404 RESTORE_SWITCH_STACK
405 ret
406
407 ENTRY(sys_rt_sigreturn)
408 SAVE_SWITCH_STACK
409 mov r4, sp
410 call do_rt_sigreturn
411 RESTORE_SWITCH_STACK
412 addi ra, ra, (end_translate_rc_and_
413 ret
414
415 /*********************************************
416 * A few other wrappers and stubs
417 *********************************************
418 */
419 protection_exception_pte:
420 rdctl r6, pteaddr
421 slli r6, r6, 10
422 call do_page_fault
423 br ret_from_exception
424
425 protection_exception_ba:
426 rdctl r6, badaddr
427 call do_page_fault
428 br ret_from_exception
429
430 protection_exception_instr:
431 call handle_supervisor_instr
432 br ret_from_exception
433
434 handle_breakpoint:
435 call breakpoint_c
436 br ret_from_exception
437
438 #ifdef CONFIG_NIOS2_ALIGNMENT_TRAP
439 handle_unaligned:
440 SAVE_SWITCH_STACK
441 call handle_unaligned_c
442 RESTORE_SWITCH_STACK
443 br ret_from_exception
444 #else
445 handle_unaligned:
446 call handle_unaligned_c
447 br ret_from_exception
448 #endif
449
450 handle_illegal:
451 call handle_illegal_c
452 br ret_from_exception
453
454 handle_diverror:
455 call handle_diverror_c
456 br ret_from_exception
457
458 #ifdef CONFIG_KGDB
459 handle_kgdb_breakpoint:
460 call kgdb_breakpoint_c
461 br ret_from_exception
462 #endif
463
464 handle_trap_1:
465 call handle_trap_1_c
466 br ret_from_exception
467
468 handle_trap_2:
469 call handle_trap_2_c
470 br ret_from_exception
471
472 handle_trap_3:
473 handle_trap_reserved:
474 call handle_trap_3_c
475 br ret_from_exception
476
477 /*
478 * Beware - when entering resume, prev (the cu
479 * in r4, next (the new task) is in r5, don't
480 * registers.
481 */
482 ENTRY(resume)
483
484 rdctl r7, status
485 stw r7, TASK_THREAD + THREAD_KPSR(
486
487 andi r7, r7, %lo(~STATUS_PIE)
488 wrctl status, r7
489
490 SAVE_SWITCH_STACK
491 stw sp, TASK_THREAD + THREAD_KSP(r
492 ldw sp, TASK_THREAD + THREAD_KSP(r
493 movia r24, _current_thread
494 GET_THREAD_INFO r1
495 stw r1, 0(r24)
496 RESTORE_SWITCH_STACK
497
498 ldw r7, TASK_THREAD + THREAD_KPSR(
499 wrctl status, r7
500 ret
501
502 ENTRY(ret_from_fork)
503 call schedule_tail
504 br ret_from_exception
505
506 ENTRY(ret_from_kernel_thread)
507 call schedule_tail
508 mov r4,r17 /* arg */
509 callr r16 /* function */
510 br ret_from_exception
511
512 /*
513 * Kernel user helpers.
514 *
515 * Each segment is 64-byte aligned and will be
516 * New segments (if ever needed) must be added
517 * This mechanism should be used only for thin
518 * justified, and not be abused freely.
519 *
520 */
521
522 /* Filling pads with undefined instructions.
523 .macro kuser_pad sym size
524 .if ((. - \sym) & 3)
525 .rept (4 - (. - \sym) & 3)
526 .byte 0
527 .endr
528 .endif
529 .rept ((\size - (. - \sym)) / 4)
530 .word 0xdeadbeef
531 .endr
532 .endm
533
534 .align 6
535 .globl __kuser_helper_start
536 __kuser_helper_start:
537
538 __kuser_helper_version:
539 .word ((__kuser_helper_end - __kuser
540
541 __kuser_cmpxchg:
542 /*
543 * r4 pointer to exchange variable
544 * r5 old value
545 * r6 new value
546 */
547 cmpxchg_ldw:
548 ldw r2, 0(r4)
549 sub r2, r2, r5
550 bne r2, zero, cmpxchg_ret
551
552 /* We had a match, store the new value
553 cmpxchg_stw:
554 stw r6, 0(r4)
555 cmpxchg_ret:
556 ret
557
558 kuser_pad __kuser_cmpxchg, 64
559
560 .globl __kuser_sigtramp
561 __kuser_sigtramp:
562 movi r2, __NR_rt_sigreturn
563 trap
564
565 kuser_pad __kuser_sigtramp, 64
566
567 .globl __kuser_helper_end
568 __kuser_helper_end:
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