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82ed08dd LFT |
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 and ivarholmqvist@gmail.com | |
8 | * | |
9 | * Copyright (C) 1999-2002, Greg Ungerer (gerg@snapgear.com) | |
10 | * Copyright (C) 1998 D. Jeff Dionne <jeff@lineo.ca>, | |
11 | * Kenneth Albanowski <kjahds@kjahds.com>, | |
12 | * Copyright (C) 2000 Lineo Inc. (www.lineo.com) | |
13 | * Copyright (C) 2004 Microtronix Datacom Ltd. | |
14 | * | |
15 | * This file is subject to the terms and conditions of the GNU General Public | |
16 | * License. See the file "COPYING" in the main directory of this archive | |
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@snapgear.com) | |
23 | * 5307 fixes by David W. Miller | |
24 | * linux 2.4 support David McCullough <davidm@snapgear.com> | |
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 helper is restarted if it was | |
50 | * interrupted in a critical region. | |
51 | * ea-4 = address of interrupted insn (ea must be preserved). | |
52 | * sp = saved regs. | |
53 | * cmpxchg_ldw = first critical insn, cmpxchg_stw = last critical insn. | |
54 | * If ea <= cmpxchg_stw and ea > cmpxchg_ldw then saved EA is set to | |
55 | * cmpxchg_ldw + 4. | |
56 | */ | |
57 | /* et = cmpxchg_stw + 4 */ | |
58 | movui et, (KUSER_BASE + 4 + (cmpxchg_stw - __kuser_helper_start)) | |
59 | bgtu ea, et, 1f | |
60 | ||
61 | subi et, et, (cmpxchg_stw - cmpxchg_ldw) /* et = cmpxchg_ldw + 4 */ | |
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 - Reset */ | |
72 | .word unhandled_exception /* 1 - Processor-only Reset */ | |
73 | .word external_interrupt /* 2 - Interrupt */ | |
74 | .word handle_trap /* 3 - Trap Instruction */ | |
75 | ||
76 | .word instruction_trap /* 4 - Unimplemented instruction */ | |
77 | .word handle_illegal /* 5 - Illegal instruction */ | |
78 | .word handle_unaligned /* 6 - Misaligned data access */ | |
79 | .word handle_unaligned /* 7 - Misaligned destination address */ | |
80 | ||
81 | .word handle_diverror /* 8 - Division error */ | |
82 | .word protection_exception_ba /* 9 - Supervisor-only instr. address */ | |
83 | .word protection_exception_instr /* 10 - Supervisor only instruction */ | |
84 | .word protection_exception_ba /* 11 - Supervisor only data address */ | |
85 | ||
86 | .word unhandled_exception /* 12 - Double TLB miss (data) */ | |
87 | .word protection_exception_pte /* 13 - TLB permission violation (x) */ | |
88 | .word protection_exception_pte /* 14 - TLB permission violation (r) */ | |
89 | .word protection_exception_pte /* 15 - TLB permission violation (w) */ | |
90 | ||
91 | .word unhandled_exception /* 16 - MPU region violation */ | |
92 | ||
93 | trap_table: | |
94 | .word handle_system_call /* 0 */ | |
95 | .word instruction_trap /* 1 */ | |
96 | .word instruction_trap /* 2 */ | |
97 | .word instruction_trap /* 3 */ | |
98 | .word instruction_trap /* 4 */ | |
99 | .word instruction_trap /* 5 */ | |
100 | .word instruction_trap /* 6 */ | |
101 | .word instruction_trap /* 7 */ | |
102 | .word instruction_trap /* 8 */ | |
103 | .word instruction_trap /* 9 */ | |
104 | .word instruction_trap /* 10 */ | |
105 | .word instruction_trap /* 11 */ | |
106 | .word instruction_trap /* 12 */ | |
107 | .word instruction_trap /* 13 */ | |
108 | .word instruction_trap /* 14 */ | |
109 | .word instruction_trap /* 15 */ | |
110 | .word instruction_trap /* 16 */ | |
111 | .word instruction_trap /* 17 */ | |
112 | .word instruction_trap /* 18 */ | |
113 | .word instruction_trap /* 19 */ | |
114 | .word instruction_trap /* 20 */ | |
115 | .word instruction_trap /* 21 */ | |
116 | .word instruction_trap /* 22 */ | |
117 | .word instruction_trap /* 23 */ | |
118 | .word instruction_trap /* 24 */ | |
119 | .word instruction_trap /* 25 */ | |
120 | .word instruction_trap /* 26 */ | |
121 | .word instruction_trap /* 27 */ | |
122 | .word instruction_trap /* 28 */ | |
123 | .word instruction_trap /* 29 */ | |
124 | .word instruction_trap /* 30 */ | |
125 | .word handle_breakpoint /* 31 */ | |
126 | ||
127 | .text | |
128 | .set noat | |
129 | .set nobreak | |
130 | ||
131 | ENTRY(inthandler) | |
132 | SAVE_ALL | |
133 | ||
134 | kuser_cmpxchg_check | |
135 | ||
136 | /* Clear EH bit before we get a new excpetion in the kernel | |
137 | * and after we have saved it to the exception frame. This is done | |
138 | * whether it's trap, tlb-miss or interrupt. If we don't do this | |
139 | * estatus is not updated the next exception. | |
140 | */ | |
141 | rdctl r24, status | |
142 | movi r9, %lo(~STATUS_EH) | |
143 | and r24, r24, r9 | |
144 | wrctl status, r24 | |
145 | ||
146 | /* Read cause and vector and branch to the associated handler */ | |
147 | mov r4, sp | |
148 | rdctl r5, exception | |
149 | movia r9, exception_table | |
150 | add r24, r9, r5 | |
151 | ldw r24, 0(r24) | |
152 | jmp r24 | |
153 | ||
154 | ||
155 | /*********************************************************************** | |
156 | * Handle traps | |
157 | *********************************************************************** | |
158 | */ | |
159 | ENTRY(handle_trap) | |
160 | ldw r24, -4(ea) /* instruction that caused the exception */ | |
161 | srli r24, r24, 4 | |
162 | andi r24, r24, 0x7c | |
163 | movia r9,trap_table | |
164 | add r24, r24, r9 | |
165 | ldw r24, 0(r24) | |
166 | jmp r24 | |
167 | ||
168 | ||
169 | /*********************************************************************** | |
170 | * Handle system calls | |
171 | *********************************************************************** | |
172 | */ | |
173 | ENTRY(handle_system_call) | |
174 | /* Enable interrupts */ | |
175 | rdctl r10, status | |
176 | ori r10, r10, STATUS_PIE | |
177 | wrctl status, r10 | |
178 | ||
179 | /* Reload registers destroyed by common code. */ | |
180 | ldw r4, PT_R4(sp) | |
181 | ldw r5, PT_R5(sp) | |
182 | ||
183 | local_restart: | |
184 | /* Check that the requested system call is within limits */ | |
185 | movui r1, __NR_syscalls | |
186 | bgeu r2, r1, ret_invsyscall | |
187 | slli r1, r2, 2 | |
188 | movhi r11, %hiadj(sys_call_table) | |
189 | add r1, r1, r11 | |
190 | ldw r1, %lo(sys_call_table)(r1) | |
191 | beq r1, r0, ret_invsyscall | |
192 | ||
193 | /* Check if we are being traced */ | |
194 | GET_THREAD_INFO r11 | |
195 | ldw r11,TI_FLAGS(r11) | |
196 | BTBNZ r11,r11,TIF_SYSCALL_TRACE,traced_system_call | |
197 | ||
198 | /* Execute the system call */ | |
199 | callr r1 | |
200 | ||
201 | /* If the syscall returns a negative result: | |
202 | * Set r7 to 1 to indicate error, | |
203 | * Negate r2 to get a positive error code | |
204 | * If the syscall returns zero or a positive value: | |
205 | * Set r7 to 0. | |
206 | * The sigreturn system calls will skip the code below by | |
207 | * adding to register ra. To avoid destroying registers | |
208 | */ | |
209 | translate_rc_and_ret: | |
210 | movi r1, 0 | |
211 | bge r2, zero, 3f | |
212 | sub r2, zero, r2 | |
213 | movi r1, 1 | |
214 | 3: | |
215 | stw r2, PT_R2(sp) | |
216 | stw r1, PT_R7(sp) | |
217 | end_translate_rc_and_ret: | |
218 | ||
219 | ret_from_exception: | |
220 | ldw r1, PT_ESTATUS(sp) | |
221 | /* if so, skip resched, signals */ | |
222 | TSTBNZ r1, r1, ESTATUS_EU, Luser_return | |
223 | ||
224 | restore_all: | |
225 | rdctl r10, status /* disable intrs */ | |
226 | andi r10, r10, %lo(~STATUS_PIE) | |
227 | wrctl status, r10 | |
228 | RESTORE_ALL | |
229 | eret | |
230 | ||
231 | /* If the syscall number was invalid return ENOSYS */ | |
232 | ret_invsyscall: | |
233 | movi r2, -ENOSYS | |
234 | br translate_rc_and_ret | |
235 | ||
236 | /* This implements the same as above, except it calls | |
237 | * do_syscall_trace_enter and do_syscall_trace_exit before and after the | |
238 | * syscall in order for utilities like strace and gdb to work. | |
239 | */ | |
240 | traced_system_call: | |
241 | SAVE_SWITCH_STACK | |
242 | call do_syscall_trace_enter | |
243 | RESTORE_SWITCH_STACK | |
244 | ||
245 | /* Create system call register arguments. The 5th and 6th | |
246 | arguments on stack are already in place at the beginning | |
247 | of pt_regs. */ | |
248 | ldw r2, PT_R2(sp) | |
249 | ldw r4, PT_R4(sp) | |
250 | ldw r5, PT_R5(sp) | |
251 | ldw r6, PT_R6(sp) | |
252 | ldw r7, PT_R7(sp) | |
253 | ||
254 | /* Fetch the syscall function, we don't need to check the boundaries | |
255 | * since this is already done. | |
256 | */ | |
257 | slli r1, r2, 2 | |
258 | movhi r11,%hiadj(sys_call_table) | |
259 | add r1, r1, r11 | |
260 | ldw r1, %lo(sys_call_table)(r1) | |
261 | ||
262 | callr r1 | |
263 | ||
264 | /* If the syscall returns a negative result: | |
265 | * Set r7 to 1 to indicate error, | |
266 | * Negate r2 to get a positive error code | |
267 | * If the syscall returns zero or a positive value: | |
268 | * Set r7 to 0. | |
269 | * The sigreturn system calls will skip the code below by | |
270 | * adding to register ra. To avoid destroying registers | |
271 | */ | |
272 | translate_rc_and_ret2: | |
273 | movi r1, 0 | |
274 | bge r2, zero, 4f | |
275 | sub r2, zero, r2 | |
276 | movi r1, 1 | |
277 | 4: | |
278 | stw r2, PT_R2(sp) | |
279 | stw r1, PT_R7(sp) | |
280 | end_translate_rc_and_ret2: | |
281 | SAVE_SWITCH_STACK | |
282 | call do_syscall_trace_exit | |
283 | RESTORE_SWITCH_STACK | |
284 | br ret_from_exception | |
285 | ||
286 | Luser_return: | |
287 | GET_THREAD_INFO r11 /* get thread_info pointer */ | |
288 | ldw r10, TI_FLAGS(r11) /* get thread_info->flags */ | |
289 | ANDI32 r11, r10, _TIF_WORK_MASK | |
290 | beq r11, r0, restore_all /* Nothing to do */ | |
291 | BTBZ r1, r10, TIF_NEED_RESCHED, Lsignal_return | |
292 | ||
293 | /* Reschedule work */ | |
294 | call schedule | |
295 | br ret_from_exception | |
296 | ||
297 | Lsignal_return: | |
298 | ANDI32 r1, r10, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME | |
299 | beq r1, r0, restore_all | |
300 | mov r4, sp /* pt_regs */ | |
301 | SAVE_SWITCH_STACK | |
302 | call do_notify_resume | |
303 | beq r2, r0, no_work_pending | |
304 | RESTORE_SWITCH_STACK | |
305 | /* prepare restart syscall here without leaving kernel */ | |
306 | ldw r2, PT_R2(sp) /* reload syscall number in r2 */ | |
307 | ldw r4, PT_R4(sp) /* reload syscall arguments r4-r9 */ | |
308 | ldw r5, PT_R5(sp) | |
309 | ldw r6, PT_R6(sp) | |
310 | ldw r7, PT_R7(sp) | |
311 | ldw r8, PT_R8(sp) | |
312 | ldw r9, PT_R9(sp) | |
313 | br local_restart /* restart syscall */ | |
314 | ||
315 | no_work_pending: | |
316 | RESTORE_SWITCH_STACK | |
317 | br ret_from_exception | |
318 | ||
319 | /*********************************************************************** | |
320 | * Handle external interrupts. | |
321 | *********************************************************************** | |
322 | */ | |
323 | /* | |
324 | * This is the generic interrupt handler (for all hardware interrupt | |
325 | * sources). It figures out the vector number and calls the appropriate | |
326 | * interrupt service routine directly. | |
327 | */ | |
328 | external_interrupt: | |
329 | rdctl r12, ipending | |
330 | rdctl r9, ienable | |
331 | and r12, r12, r9 | |
332 | /* skip if no interrupt is pending */ | |
333 | beq r12, r0, ret_from_interrupt | |
334 | ||
335 | movi r24, -1 | |
336 | stw r24, PT_ORIG_R2(sp) | |
337 | ||
338 | /* | |
339 | * Process an external hardware interrupt. | |
340 | */ | |
341 | ||
342 | addi ea, ea, -4 /* re-issue the interrupted instruction */ | |
343 | stw ea, PT_EA(sp) | |
344 | 2: movi r4, %lo(-1) /* Start from bit position 0, | |
345 | highest priority */ | |
346 | /* This is the IRQ # for handler call */ | |
347 | 1: andi r10, r12, 1 /* Isolate bit we are interested in */ | |
348 | srli r12, r12, 1 /* shift count is costly without hardware | |
349 | multiplier */ | |
350 | addi r4, r4, 1 | |
351 | beq r10, r0, 1b | |
352 | mov r5, sp /* Setup pt_regs pointer for handler call */ | |
353 | call do_IRQ | |
354 | rdctl r12, ipending /* check again if irq still pending */ | |
355 | rdctl r9, ienable /* Isolate possible interrupts */ | |
356 | and r12, r12, r9 | |
357 | bne r12, r0, 2b | |
358 | /* br ret_from_interrupt */ /* fall through to ret_from_interrupt */ | |
359 | ||
360 | ENTRY(ret_from_interrupt) | |
361 | ldw r1, PT_ESTATUS(sp) /* check if returning to kernel */ | |
362 | TSTBNZ r1, r1, ESTATUS_EU, Luser_return | |
363 | ||
364 | #ifdef CONFIG_PREEMPT | |
365 | GET_THREAD_INFO r1 | |
366 | ldw r4, TI_PREEMPT_COUNT(r1) | |
367 | bne r4, r0, restore_all | |
368 | ||
369 | need_resched: | |
370 | ldw r4, TI_FLAGS(r1) /* ? Need resched set */ | |
371 | BTBZ r10, r4, TIF_NEED_RESCHED, restore_all | |
372 | ldw r4, PT_ESTATUS(sp) /* ? Interrupts off */ | |
373 | andi r10, r4, ESTATUS_EPIE | |
374 | beq r10, r0, restore_all | |
375 | movia r4, PREEMPT_ACTIVE | |
376 | stw r4, TI_PREEMPT_COUNT(r1) | |
377 | rdctl r10, status /* enable intrs again */ | |
378 | ori r10, r10 ,STATUS_PIE | |
379 | wrctl status, r10 | |
380 | PUSH r1 | |
381 | call schedule | |
382 | POP r1 | |
383 | mov r4, r0 | |
384 | stw r4, TI_PREEMPT_COUNT(r1) | |
385 | rdctl r10, status /* disable intrs */ | |
386 | andi r10, r10, %lo(~STATUS_PIE) | |
387 | wrctl status, r10 | |
388 | br need_resched | |
389 | #else | |
390 | br restore_all | |
391 | #endif | |
392 | ||
393 | /*********************************************************************** | |
394 | * A few syscall wrappers | |
395 | *********************************************************************** | |
396 | */ | |
397 | /* | |
398 | * int clone(unsigned long clone_flags, unsigned long newsp, | |
399 | * int __user * parent_tidptr, int __user * child_tidptr, | |
400 | * int tls_val) | |
401 | */ | |
402 | ENTRY(sys_clone) | |
403 | SAVE_SWITCH_STACK | |
404 | addi sp, sp, -4 | |
405 | stw r7, 0(sp) /* Pass 5th arg thru stack */ | |
406 | mov r7, r6 /* 4th arg is 3rd of clone() */ | |
407 | mov r6, zero /* 3rd arg always 0 */ | |
408 | call do_fork | |
409 | addi sp, sp, 4 | |
410 | RESTORE_SWITCH_STACK | |
411 | ret | |
412 | ||
413 | ENTRY(sys_rt_sigreturn) | |
414 | SAVE_SWITCH_STACK | |
415 | mov r4, sp | |
416 | call do_rt_sigreturn | |
417 | RESTORE_SWITCH_STACK | |
418 | addi ra, ra, (end_translate_rc_and_ret - translate_rc_and_ret) | |
419 | ret | |
420 | ||
421 | /*********************************************************************** | |
422 | * A few other wrappers and stubs | |
423 | *********************************************************************** | |
424 | */ | |
425 | protection_exception_pte: | |
426 | rdctl r6, pteaddr | |
427 | slli r6, r6, 10 | |
428 | call do_page_fault | |
429 | br ret_from_exception | |
430 | ||
431 | protection_exception_ba: | |
432 | rdctl r6, badaddr | |
433 | call do_page_fault | |
434 | br ret_from_exception | |
435 | ||
436 | protection_exception_instr: | |
437 | call handle_supervisor_instr | |
438 | br ret_from_exception | |
439 | ||
440 | handle_breakpoint: | |
441 | call breakpoint_c | |
442 | br ret_from_exception | |
443 | ||
444 | #ifdef CONFIG_NIOS2_ALIGNMENT_TRAP | |
445 | handle_unaligned: | |
446 | SAVE_SWITCH_STACK | |
447 | call handle_unaligned_c | |
448 | RESTORE_SWITCH_STACK | |
449 | br ret_from_exception | |
450 | #else | |
451 | handle_unaligned: | |
452 | call handle_unaligned_c | |
453 | br ret_from_exception | |
454 | #endif | |
455 | ||
456 | handle_illegal: | |
457 | call handle_illegal_c | |
458 | br ret_from_exception | |
459 | ||
460 | handle_diverror: | |
461 | call handle_diverror_c | |
462 | br ret_from_exception | |
463 | ||
464 | /* | |
465 | * Beware - when entering resume, prev (the current task) is | |
466 | * in r4, next (the new task) is in r5, don't change these | |
467 | * registers. | |
468 | */ | |
469 | ENTRY(resume) | |
470 | ||
471 | rdctl r7, status /* save thread status reg */ | |
472 | stw r7, TASK_THREAD + THREAD_KPSR(r4) | |
473 | ||
474 | andi r7, r7, %lo(~STATUS_PIE) /* disable interrupts */ | |
475 | wrctl status, r7 | |
476 | ||
477 | SAVE_SWITCH_STACK | |
478 | stw sp, TASK_THREAD + THREAD_KSP(r4)/* save kernel stack pointer */ | |
479 | ldw sp, TASK_THREAD + THREAD_KSP(r5)/* restore new thread stack */ | |
480 | movia r24, _current_thread /* save thread */ | |
481 | GET_THREAD_INFO r1 | |
482 | stw r1, 0(r24) | |
483 | RESTORE_SWITCH_STACK | |
484 | ||
485 | ldw r7, TASK_THREAD + THREAD_KPSR(r5)/* restore thread status reg */ | |
486 | wrctl status, r7 | |
487 | ret | |
488 | ||
489 | ENTRY(ret_from_fork) | |
490 | call schedule_tail | |
491 | br ret_from_exception | |
492 | ||
493 | ENTRY(ret_from_kernel_thread) | |
494 | call schedule_tail | |
495 | mov r4,r17 /* arg */ | |
496 | callr r16 /* function */ | |
497 | br ret_from_exception | |
498 | ||
499 | /* | |
500 | * Kernel user helpers. | |
501 | * | |
502 | * Each segment is 64-byte aligned and will be mapped to the <User space>. | |
503 | * New segments (if ever needed) must be added after the existing ones. | |
504 | * This mechanism should be used only for things that are really small and | |
505 | * justified, and not be abused freely. | |
506 | * | |
507 | */ | |
508 | ||
509 | /* Filling pads with undefined instructions. */ | |
510 | .macro kuser_pad sym size | |
511 | .if ((. - \sym) & 3) | |
512 | .rept (4 - (. - \sym) & 3) | |
513 | .byte 0 | |
514 | .endr | |
515 | .endif | |
516 | .rept ((\size - (. - \sym)) / 4) | |
517 | .word 0xdeadbeef | |
518 | .endr | |
519 | .endm | |
520 | ||
521 | .align 6 | |
522 | .globl __kuser_helper_start | |
523 | __kuser_helper_start: | |
524 | ||
525 | __kuser_helper_version: /* @ 0x1000 */ | |
526 | .word ((__kuser_helper_end - __kuser_helper_start) >> 6) | |
527 | ||
528 | __kuser_cmpxchg: /* @ 0x1004 */ | |
529 | /* | |
530 | * r4 pointer to exchange variable | |
531 | * r5 old value | |
532 | * r6 new value | |
533 | */ | |
534 | cmpxchg_ldw: | |
535 | ldw r2, 0(r4) /* load current value */ | |
536 | sub r2, r2, r5 /* compare with old value */ | |
537 | bne r2, zero, cmpxchg_ret | |
538 | ||
539 | /* We had a match, store the new value */ | |
540 | cmpxchg_stw: | |
541 | stw r6, 0(r4) | |
542 | cmpxchg_ret: | |
543 | ret | |
544 | ||
545 | kuser_pad __kuser_cmpxchg, 64 | |
546 | ||
547 | .globl __kuser_sigtramp | |
548 | __kuser_sigtramp: | |
549 | movi r2, __NR_rt_sigreturn | |
550 | trap | |
551 | ||
552 | kuser_pad __kuser_sigtramp, 64 | |
553 | ||
554 | .globl __kuser_helper_end | |
555 | __kuser_helper_end: |