aboutsummaryrefslogtreecommitdiffstats
path: root/arch/alpha/kernel/entry.S
blob: ab1ee0ab082b996fd0d656b62baa2fcccab7b0b8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
/*
 * arch/alpha/kernel/entry.S
 *
 * Kernel entry-points.
 */

#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/pal.h>
#include <asm/errno.h>
#include <asm/unistd.h>

	.text
	.set noat

/* Stack offsets.  */
#define SP_OFF			184
#define SWITCH_STACK_SIZE	320

/*
 * This defines the normal kernel pt-regs layout.
 *
 * regs 9-15 preserved by C code
 * regs 16-18 saved by PAL-code
 * regs 29-30 saved and set up by PAL-code
 * JRP - Save regs 16-18 in a special area of the stack, so that
 * the palcode-provided values are available to the signal handler.
 */

#define SAVE_ALL			\
	subq	$sp, SP_OFF, $sp;	\
	stq	$0, 0($sp);		\
	stq	$1, 8($sp);		\
	stq	$2, 16($sp);		\
	stq	$3, 24($sp);		\
	stq	$4, 32($sp);		\
	stq	$28, 144($sp);		\
	lda	$2, alpha_mv;		\
	stq	$5, 40($sp);		\
	stq	$6, 48($sp);		\
	stq	$7, 56($sp);		\
	stq	$8, 64($sp);		\
	stq	$19, 72($sp);		\
	stq	$20, 80($sp);		\
	stq	$21, 88($sp);		\
	ldq	$2, HAE_CACHE($2);	\
	stq	$22, 96($sp);		\
	stq	$23, 104($sp);		\
	stq	$24, 112($sp);		\
	stq	$25, 120($sp);		\
	stq	$26, 128($sp);		\
	stq	$27, 136($sp);		\
	stq	$2, 152($sp);		\
	stq	$16, 160($sp);		\
	stq	$17, 168($sp);		\
	stq	$18, 176($sp)

#define RESTORE_ALL			\
	lda	$19, alpha_mv;		\
	ldq	$0, 0($sp);		\
	ldq	$1, 8($sp);		\
	ldq	$2, 16($sp);		\
	ldq	$3, 24($sp);		\
	ldq	$21, 152($sp);		\
	ldq	$20, HAE_CACHE($19);	\
	ldq	$4, 32($sp);		\
	ldq	$5, 40($sp);		\
	ldq	$6, 48($sp);		\
	ldq	$7, 56($sp);		\
	subq	$20, $21, $20;		\
	ldq	$8, 64($sp);		\
	beq	$20, 99f;		\
	ldq	$20, HAE_REG($19);	\
	stq	$21, HAE_CACHE($19);	\
	stq	$21, 0($20);		\
	ldq	$0, 0($sp);		\
	ldq	$1, 8($sp);		\
99:;					\
	ldq	$19, 72($sp);		\
	ldq	$20, 80($sp);		\
	ldq	$21, 88($sp);		\
	ldq	$22, 96($sp);		\
	ldq	$23, 104($sp);		\
	ldq	$24, 112($sp);		\
	ldq	$25, 120($sp);		\
	ldq	$26, 128($sp);		\
	ldq	$27, 136($sp);		\
	ldq	$28, 144($sp);		\
	addq	$sp, SP_OFF, $sp

/*
 * Non-syscall kernel entry points.
 */

	.align	4
	.globl	entInt
	.ent	entInt
entInt:
	SAVE_ALL
	lda	$8, 0x3fff
	lda	$26, ret_from_sys_call
	bic	$sp, $8, $8
	mov	$sp, $19
	jsr	$31, do_entInt
.end entInt

	.align	4
	.globl	entArith
	.ent	entArith
entArith:
	SAVE_ALL
	lda	$8, 0x3fff
	lda	$26, ret_from_sys_call
	bic	$sp, $8, $8
	mov	$sp, $18
	jsr	$31, do_entArith
.end entArith

	.align	4
	.globl	entMM
	.ent	entMM
entMM:
	SAVE_ALL
/* save $9 - $15 so the inline exception code can manipulate them.  */
	subq	$sp, 56, $sp
	stq	$9, 0($sp)
	stq	$10, 8($sp)
	stq	$11, 16($sp)
	stq	$12, 24($sp)
	stq	$13, 32($sp)
	stq	$14, 40($sp)
	stq	$15, 48($sp)
	addq	$sp, 56, $19
/* handle the fault */
	lda	$8, 0x3fff
	bic	$sp, $8, $8
	jsr	$26, do_page_fault
/* reload the registers after the exception code played.  */
	ldq	$9, 0($sp)
	ldq	$10, 8($sp)
	ldq	$11, 16($sp)
	ldq	$12, 24($sp)
	ldq	$13, 32($sp)
	ldq	$14, 40($sp)
	ldq	$15, 48($sp)
	addq	$sp, 56, $sp
/* finish up the syscall as normal.  */
	br	ret_from_sys_call
.end entMM

	.align	4
	.globl	entIF
	.ent	entIF
entIF:
	SAVE_ALL
	lda	$8, 0x3fff
	lda	$26, ret_from_sys_call
	bic	$sp, $8, $8
	mov	$sp, $17
	jsr	$31, do_entIF
.end entIF

	.align	4
	.globl	entUna
	.ent	entUna
entUna:
	lda	$sp, -256($sp)
	stq	$0, 0($sp)
	ldq	$0, 256($sp)	/* get PS */
	stq	$1, 8($sp)
	stq	$2, 16($sp)
	stq	$3, 24($sp)
	and	$0, 8, $0		/* user mode? */
	stq	$4, 32($sp)
	bne	$0, entUnaUser	/* yup -> do user-level unaligned fault */
	stq	$5, 40($sp)
	stq	$6, 48($sp)
	stq	$7, 56($sp)
	stq	$8, 64($sp)
	stq	$9, 72($sp)
	stq	$10, 80($sp)
	stq	$11, 88($sp)
	stq	$12, 96($sp)
	stq	$13, 104($sp)
	stq	$14, 112($sp)
	stq	$15, 120($sp)
	/* 16-18 PAL-saved */
	stq	$19, 152($sp)
	stq	$20, 160($sp)
	stq	$21, 168($sp)
	stq	$22, 176($sp)
	stq	$23, 184($sp)
	stq	$24, 192($sp)
	stq	$25, 200($sp)
	stq	$26, 208($sp)
	stq	$27, 216($sp)
	stq	$28, 224($sp)
	mov	$sp, $19
	stq	$gp, 232($sp)
	lda	$8, 0x3fff
	stq	$31, 248($sp)
	bic	$sp, $8, $8
	jsr	$26, do_entUna
	ldq	$0, 0($sp)
	ldq	$1, 8($sp)
	ldq	$2, 16($sp)
	ldq	$3, 24($sp)
	ldq	$4, 32($sp)
	ldq	$5, 40($sp)
	ldq	$6, 48($sp)
	ldq	$7, 56($sp)
	ldq	$8, 64($sp)
	ldq	$9, 72($sp)
	ldq	$10, 80($sp)
	ldq	$11, 88($sp)
	ldq	$12, 96($sp)
	ldq	$13, 104($sp)
	ldq	$14, 112($sp)
	ldq	$15, 120($sp)
	/* 16-18 PAL-saved */
	ldq	$19, 152($sp)
	ldq	$20, 160($sp)
	ldq	$21, 168($sp)
	ldq	$22, 176($sp)
	ldq	$23, 184($sp)
	ldq	$24, 192($sp)
	ldq	$25, 200($sp)
	ldq	$26, 208($sp)
	ldq	$27, 216($sp)
	ldq	$28, 224($sp)
	ldq	$gp, 232($sp)
	lda	$sp, 256($sp)
	call_pal PAL_rti
.end entUna

	.align	4
	.ent	entUnaUser
entUnaUser:
	ldq	$0, 0($sp)	/* restore original $0 */
	lda	$sp, 256($sp)	/* pop entUna's stack frame */
	SAVE_ALL		/* setup normal kernel stack */
	lda	$sp, -56($sp)
	stq	$9, 0($sp)
	stq	$10, 8($sp)
	stq	$11, 16($sp)
	stq	$12, 24($sp)
	stq	$13, 32($sp)
	stq	$14, 40($sp)
	stq	$15, 48($sp)
	lda	$8, 0x3fff
	addq	$sp, 56, $19
	bic	$sp, $8, $8
	jsr	$26, do_entUnaUser
	ldq	$9, 0($sp)
	ldq	$10, 8($sp)
	ldq	$11, 16($sp)
	ldq	$12, 24($sp)
	ldq	$13, 32($sp)
	ldq	$14, 40($sp)
	ldq	$15, 48($sp)
	lda	$sp, 56($sp)
	br	ret_from_sys_call
.end entUnaUser

	.align	4
	.globl	entDbg
	.ent	entDbg
entDbg:
	SAVE_ALL
	lda	$8, 0x3fff
	lda	$26, ret_from_sys_call
	bic	$sp, $8, $8
	mov	$sp, $16
	jsr	$31, do_entDbg
.end entDbg

/*
 * The system call entry point is special.  Most importantly, it looks
 * like a function call to userspace as far as clobbered registers.  We
 * do preserve the argument registers (for syscall restarts) and $26
 * (for leaf syscall functions).
 *
 * So much for theory.  We don't take advantage of this yet.
 *
 * Note that a0-a2 are not saved by PALcode as with the other entry points.
 */

	.align	4
	.globl	entSys
	.globl	ret_from_sys_call
	.ent	entSys
entSys:
	SAVE_ALL
	lda	$8, 0x3fff
	bic	$sp, $8, $8
	lda	$4, NR_SYSCALLS($31)
	stq	$16, SP_OFF+24($sp)
	lda	$5, sys_call_table
	lda	$27, sys_ni_syscall
	cmpult	$0, $4, $4
	ldl	$3, TI_FLAGS($8)
	stq	$17, SP_OFF+32($sp)
	s8addq	$0, $5, $5
	stq	$18, SP_OFF+40($sp)
	blbs	$3, strace
	beq	$4, 1f
	ldq	$27, 0($5)
1:	jsr	$26, ($27), alpha_ni_syscall
	ldgp	$gp, 0($26)
	blt	$0, $syscall_error	/* the call failed */
	stq	$0, 0($sp)
	stq	$31, 72($sp)		/* a3=0 => no error */

	.align	4
ret_from_sys_call:
	cmovne	$26, 0, $19		/* $19 = 0 => non-restartable */
	ldq	$0, SP_OFF($sp)
	and	$0, 8, $0
	beq	$0, restore_all
ret_to_user:
	/* Make sure need_resched and sigpending don't change between
		sampling and the rti.  */
	lda	$16, 7
	call_pal PAL_swpipl
	ldl	$5, TI_FLAGS($8)
	and	$5, _TIF_WORK_MASK, $2
	bne	$2, work_pending
restore_all:
	RESTORE_ALL
	call_pal PAL_rti

	.align 3
$syscall_error:
	/*
	 * Some system calls (e.g., ptrace) can return arbitrary
	 * values which might normally be mistaken as error numbers.
	 * Those functions must zero $0 (v0) directly in the stack
	 * frame to indicate that a negative return value wasn't an
	 * error number..
	 */
	ldq	$19, 0($sp)	/* old syscall nr (zero if success) */
	beq	$19, $ret_success

	ldq	$20, 72($sp)	/* .. and this a3 */
	subq	$31, $0, $0	/* with error in v0 */
	addq	$31, 1, $1	/* set a3 for errno return */
	stq	$0, 0($sp)
	mov	$31, $26	/* tell "ret_from_sys_call" we can restart */
	stq	$1, 72($sp)	/* a3 for return */
	br	ret_from_sys_call

$ret_success:
	stq	$0, 0($sp)
	stq	$31, 72($sp)	/* a3=0 => no error */
	br	ret_from_sys_call
.end entSys

/*
 * Do all cleanup when returning from all interrupts and system calls.
 *
 * Arguments:
 *       $5: TI_FLAGS.
 *       $8: current.
 *      $19: The old syscall number, or zero if this is not a return
 *           from a syscall that errored and is possibly restartable.
 *      $20: The old a3 value
 */

	.align	4
	.ent	work_pending
work_pending:
	and	$5, _TIF_NEED_RESCHED, $2
	beq	$2, $work_notifysig

$work_resched:
	subq	$sp, 16, $sp
	stq	$19, 0($sp)              /* save syscall nr */
	stq	$20, 8($sp)              /* and error indication (a3) */
	jsr	$26, schedule
	ldq	$19, 0($sp)
	ldq	$20, 8($sp)
	addq	$sp, 16, $sp
	/* Make sure need_resched and sigpending don't change between
		sampling and the rti.  */
	lda	$16, 7
	call_pal PAL_swpipl
	ldl	$5, TI_FLAGS($8)
	and	$5, _TIF_WORK_MASK, $2
	beq	$2, restore_all
	and	$5, _TIF_NEED_RESCHED, $2
	bne	$2, $work_resched

$work_notifysig:
	mov	$sp, $16
	bsr	$1, do_switch_stack
	mov	$sp, $17
	mov	$5, $18
	mov	$19, $9		/* save old syscall number */
	mov	$20, $10	/* save old a3 */
	and	$5, _TIF_SIGPENDING, $2
	cmovne	$2, 0, $9	/* we don't want double syscall restarts */
	jsr	$26, do_notify_resume
	mov	$9, $19
	mov	$10, $20
	bsr	$1, undo_switch_stack
	br	ret_to_user
.end work_pending

/*
 * PTRACE syscall handler
 */

	.align	4
	.ent	strace
strace:
	/* set up signal stack, call syscall_trace */
	bsr	$1, do_switch_stack
	jsr	$26, syscall_trace
	bsr	$1, undo_switch_stack

	/* get the system call number and the arguments back.. */
	ldq	$0, 0($sp)
	ldq	$16, SP_OFF+24($sp)
	ldq	$17, SP_OFF+32($sp)
	ldq	$18, SP_OFF+40($sp)
	ldq	$19, 72($sp)
	ldq	$20, 80($sp)
	ldq	$21, 88($sp)

	/* get the system call pointer.. */
	lda	$1, NR_SYSCALLS($31)
	lda	$2, sys_call_table
	lda	$27, alpha_ni_syscall
	cmpult	$0, $1, $1
	s8addq	$0, $2, $2
	beq	$1, 1f
	ldq	$27, 0($2)
1:	jsr	$26, ($27), sys_gettimeofday
ret_from_straced:
	ldgp	$gp, 0($26)

	/* check return.. */
	blt	$0, $strace_error	/* the call failed */
	stq	$31, 72($sp)		/* a3=0 => no error */
$strace_success:
	stq	$0, 0($sp)		/* save return value */

	bsr	$1, do_switch_stack
	jsr	$26, syscall_trace
	bsr	$1, undo_switch_stack
	br	$31, ret_from_sys_call

	.align	3
$strace_error:
	ldq	$19, 0($sp)	/* old syscall nr (zero if success) */
	beq	$19, $strace_success
	ldq	$20, 72($sp)	/* .. and this a3 */

	subq	$31, $0, $0	/* with error in v0 */
	addq	$31, 1, $1	/* set a3 for errno return */
	stq	$0, 0($sp)
	stq	$1, 72($sp)	/* a3 for return */

	bsr	$1, do_switch_stack
	mov	$19, $9		/* save old syscall number */
	mov	$20, $10	/* save old a3 */
	jsr	$26, syscall_trace
	mov	$9, $19
	mov	$10, $20
	bsr	$1, undo_switch_stack

	mov	$31, $26	/* tell "ret_from_sys_call" we can restart */
	br	ret_from_sys_call
.end strace

/*
 * Save and restore the switch stack -- aka the balance of the user context.
 */

	.align	4
	.ent	do_switch_stack
do_switch_stack:
	lda	$sp, -SWITCH_STACK_SIZE($sp)
	stq	$9, 0($sp)
	stq	$10, 8($sp)
	stq	$11, 16($sp)
	stq	$12, 24($sp)
	stq	$13, 32($sp)
	stq	$14, 40($sp)
	stq	$15, 48($sp)
	stq	$26, 56($sp)
	stt	$f0, 64($sp)
	stt	$f1, 72($sp)
	stt	$f2, 80($sp)
	stt	$f3, 88($sp)
	stt	$f4, 96($sp)
	stt	$f5, 104($sp)
	stt	$f6, 112($sp)
	stt	$f7, 120($sp)
	stt	$f8, 128($sp)
	stt	$f9, 136($sp)
	stt	$f10, 144($sp)
	stt	$f11, 152($sp)
	stt	$f12, 160($sp)
	stt	$f13, 168($sp)
	stt	$f14, 176($sp)
	stt	$f15, 184($sp)
	stt	$f16, 192($sp)
	stt	$f17, 200($sp)
	stt	$f18, 208($sp)
	stt	$f19, 216($sp)
	stt	$f20, 224($sp)
	stt	$f21, 232($sp)
	stt	$f22, 240($sp)
	stt	$f23, 248($sp)
	stt	$f24, 256($sp)
	stt	$f25, 264($sp)
	stt	$f26, 272($sp)
	stt	$f27, 280($sp)
	mf_fpcr	$f0		# get fpcr
	stt	$f28, 288($sp)
	stt	$f29, 296($sp)
	stt	$f30, 304($sp)
	stt	$f0, 312($sp)	# save fpcr in slot of $f31
	ldt	$f0, 64($sp)	# dont let "do_switch_stack" change fp state.
	ret	$31, ($1), 1
.end do_switch_stack

	.align	4
	.ent	undo_switch_stack
undo_switch_stack:
	ldq	$9, 0($sp)
	ldq	$10, 8($sp)
	ldq	$11, 16($sp)
	ldq	$12, 24($sp)
	ldq	$13, 32($sp)
	ldq	$14, 40($sp)
	ldq	$15, 48($sp)
	ldq	$26, 56($sp)
	ldt	$f30, 312($sp)	# get saved fpcr
	ldt	$f0, 64($sp)
	ldt	$f1, 72($sp)
	ldt	$f2, 80($sp)
	ldt	$f3, 88($sp)
	mt_fpcr	$f30		# install saved fpcr
	ldt	$f4, 96($sp)
	ldt	$f5, 104($sp)
	ldt	$f6, 112($sp)
	ldt	$f7, 120($sp)
	ldt	$f8, 128($sp)
	ldt	$f9, 136($sp)
	ldt	$f10, 144($sp)
	ldt	$f11, 152($sp)
	ldt	$f12, 160($sp)
	ldt	$f13, 168($sp)
	ldt	$f14, 176($sp)
	ldt	$f15, 184($sp)
	ldt	$f16, 192($sp)
	ldt	$f17, 200($sp)
	ldt	$f18, 208($sp)
	ldt	$f19, 216($sp)
	ldt	$f20, 224($sp)
	ldt	$f21, 232($sp)
	ldt	$f22, 240($sp)
	ldt	$f23, 248($sp)
	ldt	$f24, 256($sp)
	ldt	$f25, 264($sp)
	ldt	$f26, 272($sp)
	ldt	$f27, 280($sp)
	ldt	$f28, 288($sp)
	ldt	$f29, 296($sp)
	ldt	$f30, 304($sp)
	lda	$sp, SWITCH_STACK_SIZE($sp)
	ret	$31, ($1), 1
.end undo_switch_stack

/*
 * The meat of the context switch code.
 */

	.align	4
	.globl	alpha_switch_to
	.ent	alpha_switch_to
alpha_switch_to:
	.prologue 0
	bsr	$1, do_switch_stack
	call_pal PAL_swpctx
	lda	$8, 0x3fff
	bsr	$1, undo_switch_stack
	bic	$sp, $8, $8
	mov	$17, $0
	ret
.end alpha_switch_to

/*
 * New processes begin life here.
 */

	.globl	ret_from_fork
	.align	4
	.ent	ret_from_fork
ret_from_fork:
	lda	$26, ret_from_sys_call
	mov	$17, $16
	jmp	$31, schedule_tail
.end ret_from_fork

/*
 * kernel_thread(fn, arg, clone_flags)
 */
	.align 4
	.globl	kernel_thread
	.ent	kernel_thread
kernel_thread:
	/* We can be called from a module.  */
	ldgp	$gp, 0($27)
	.prologue 1
	subq	$sp, SP_OFF+6*8, $sp
	br	$1, 2f		/* load start address */

	/* We've now "returned" from a fake system call.  */
	unop
	blt	$0, 1f		/* error?  */
	ldi	$1, 0x3fff
	beq	$20, 1f		/* parent or child?  */

	bic	$sp, $1, $8	/* in child.  */
	jsr	$26, ($27)
	ldgp	$gp, 0($26)
	mov	$0, $16
	mov	$31, $26
	jmp	$31, sys_exit

1:	ret			/* in parent.  */

	.align 4
2:	/* Fake a system call stack frame, as we can't do system calls
	   from kernel space.  Note that we store FN and ARG as they
	   need to be set up in the child for the call.  Also store $8
	   and $26 for use in the parent.  */
	stq	$31, SP_OFF($sp)	/* ps */
	stq	$1, SP_OFF+8($sp)	/* pc */
	stq	$gp, SP_OFF+16($sp)	/* gp */
	stq	$16, 136($sp)		/* $27; FN for child */
	stq	$17, SP_OFF+24($sp)	/* $16; ARG for child */
	stq	$8, 64($sp)		/* $8 */
	stq	$26, 128($sp)		/* $26 */
	/* Avoid the HAE being gratuitously wrong, to avoid restoring it.  */
	ldq	$2, alpha_mv+HAE_CACHE
	stq	$2, 152($sp)		/* HAE */

	/* Shuffle FLAGS to the front; add CLONE_VM.  */
	ldi	$1, CLONE_VM|CLONE_UNTRACED
	or	$18, $1, $16
	bsr	$26, sys_clone

	/* We don't actually care for a3 success widgetry in the kernel.
	   Not for positive errno values.  */
	stq	$0, 0($sp)		/* $0 */
	br	restore_all
.end kernel_thread

/*
 * kernel_execve(path, argv, envp)
 */
	.align	4
	.globl	kernel_execve
	.ent	kernel_execve
kernel_execve:
	/* We can be called from a module.  */
	ldgp	$gp, 0($27)
	lda	$sp, -(32+SIZEOF_PT_REGS+8)($sp)
	.frame	$sp, 32+SIZEOF_PT_REGS+8, $26, 0
	stq	$26, 0($sp)
	stq	$16, 8($sp)
	stq	$17, 16($sp)
	stq	$18, 24($sp)
	.prologue 1

	lda	$16, 32($sp)
	lda	$17, 0
	lda	$18, SIZEOF_PT_REGS
	bsr	$26, memset		!samegp

	/* Avoid the HAE being gratuitously wrong, which would cause us
	   to do the whole turn off interrupts thing and restore it.  */
	ldq	$2, alpha_mv+HAE_CACHE
	stq	$2, 152+32($sp)

	ldq	$16, 8($sp)
	ldq	$17, 16($sp)
	ldq	$18, 24($sp)
	lda	$19, 32($sp)
	bsr	$26, do_execve		!samegp

	ldq	$26, 0($sp)
	bne	$0, 1f			/* error! */

	/* Move the temporary pt_regs struct from its current location
	   to the top of the kernel stack frame.  See copy_thread for
	   details for a normal process.  */
	lda	$16, 0x4000 - SIZEOF_PT_REGS($8)
	lda	$17, 32($sp)
	lda	$18, SIZEOF_PT_REGS
	bsr	$26, memmove		!samegp

	/* Take that over as our new stack frame and visit userland!  */
	lda	$sp, 0x4000 - SIZEOF_PT_REGS($8)
	br	$31, ret_from_sys_call

1:	lda	$sp, 32+SIZEOF_PT_REGS+8($sp)
	ret
.end kernel_execve


/*
 * Special system calls.  Most of these are special in that they either
 * have to play switch_stack games or in some way use the pt_regs struct.
 */
	.align	4
	.globl	sys_fork
	.ent	sys_fork
sys_fork:
	.prologue 0
	mov	$sp, $21
	bsr	$1, do_switch_stack
	bis	$31, SIGCHLD, $16
	mov	$31, $17
	mov	$31, $18
	mov	$31, $19
	mov	$31, $20
	jsr	$26, alpha_clone
	bsr	$1, undo_switch_stack
	ret
.end sys_fork

	.align	4
	.globl	sys_clone
	.ent	sys_clone
sys_clone:
	.prologue 0
	mov	$sp, $21
	bsr	$1, do_switch_stack
	/* $16, $17, $18, $19, $20 come from the user.  */
	jsr	$26, alpha_clone
	bsr	$1, undo_switch_stack
	ret
.end sys_clone

	.align	4
	.globl	sys_vfork
	.ent	sys_vfork
sys_vfork:
	.prologue 0
	mov	$sp, $16
	bsr	$1, do_switch_stack
	jsr	$26, alpha_vfork
	bsr	$1, undo_switch_stack
	ret
.end sys_vfork

	.align	4
	.globl	sys_sigreturn
	.ent	sys_sigreturn
sys_sigreturn:
	.prologue 0
	lda	$9, ret_from_straced
	cmpult	$26, $9, $9
	mov	$sp, $17
	lda	$18, -SWITCH_STACK_SIZE($sp)
	lda	$sp, -SWITCH_STACK_SIZE($sp)
	jsr	$26, do_sigreturn
	bne	$9, 1f
	jsr	$26, syscall_trace
1:	br	$1, undo_switch_stack
	br	ret_from_sys_call
.end sys_sigreturn

	.align	4
	.globl	sys_rt_sigreturn
	.ent	sys_rt_sigreturn
sys_rt_sigreturn:
	.prologue 0
	lda	$9, ret_from_straced
	cmpult	$26, $9, $9
	mov	$sp, $17
	lda	$18, -SWITCH_STACK_SIZE($sp)
	lda	$sp, -SWITCH_STACK_SIZE($sp)
	jsr	$26, do_rt_sigreturn
	bne	$9, 1f
	jsr	$26, syscall_trace
1:	br	$1, undo_switch_stack
	br	ret_from_sys_call
.end sys_rt_sigreturn

	.align	4
	.globl	sys_sethae
	.ent	sys_sethae
sys_sethae:
	.prologue 0
	stq	$16, 152($sp)
	ret
.end sys_sethae

	.align	4
	.globl	osf_getpriority
	.ent	osf_getpriority
osf_getpriority:
	lda	$sp, -16($sp)
	stq	$26, 0($sp)
	.prologue 0

	jsr	$26, sys_getpriority

	ldq	$26, 0($sp)
	blt	$0, 1f

	/* Return value is the unbiased priority, i.e. 20 - prio.
	   This does result in negative return values, so signal
	   no error by writing into the R0 slot.  */
	lda	$1, 20
	stq	$31, 16($sp)
	subl	$1, $0, $0
	unop

1:	lda	$sp, 16($sp)
	ret
.end osf_getpriority

	.align	4
	.globl	sys_getxuid
	.ent	sys_getxuid
sys_getxuid:
	.prologue 0
	ldq	$2, TI_TASK($8)
	ldq	$3, TASK_CRED($2)
	ldl	$0, CRED_UID($3)
	ldl	$1, CRED_EUID($3)
	stq	$1, 80($sp)
	ret
.end sys_getxuid

	.align	4
	.globl	sys_getxgid
	.ent	sys_getxgid
sys_getxgid:
	.prologue 0
	ldq	$2, TI_TASK($8)
	ldq	$3, TASK_CRED($2)
	ldl	$0, CRED_GID($3)
	ldl	$1, CRED_EGID($3)
	stq	$1, 80($sp)
	ret
.end sys_getxgid

	.align	4
	.globl	sys_getxpid
	.ent	sys_getxpid
sys_getxpid:
	.prologue 0
	ldq	$2, TI_TASK($8)

	/* See linux/kernel/timer.c sys_getppid for discussion
	   about this loop.  */
	ldq	$3, TASK_GROUP_LEADER($2)
	ldq	$4, TASK_REAL_PARENT($3)
	ldl	$0, TASK_TGID($2)
1:	ldl	$1, TASK_TGID($4)
#ifdef CONFIG_SMP
	mov	$4, $5
	mb
	ldq	$3, TASK_GROUP_LEADER($2)
	ldq	$4, TASK_REAL_PARENT($3)
	cmpeq	$4, $5, $5
	beq	$5, 1b
#endif
	stq	$1, 80($sp)
	ret
.end sys_getxpid

	.align	4
	.globl	sys_alpha_pipe
	.ent	sys_alpha_pipe
sys_alpha_pipe:
	lda	$sp, -16($sp)
	stq	$26, 0($sp)
	.prologue 0

	mov	$31, $17
	lda	$16, 8($sp)
	jsr	$26, do_pipe_flags

	ldq	$26, 0($sp)
	bne	$0, 1f

	/* The return values are in $0 and $20.  */
	ldl	$1, 12($sp)
	ldl	$0, 8($sp)

	stq	$1, 80+16($sp)
1:	lda	$sp, 16($sp)
	ret
.end sys_alpha_pipe

	.align	4
	.globl	sys_execve
	.ent	sys_execve
sys_execve:
	.prologue 0
	mov	$sp, $19
	jmp	$31, do_sys_execve
.end sys_execve

	.align	4
	.globl	osf_sigprocmask
	.ent	osf_sigprocmask
osf_sigprocmask:
	.prologue 0
	mov	$sp, $18
	jmp	$31, sys_osf_sigprocmask
.end osf_sigprocmask

	.align	4
	.globl	alpha_ni_syscall
	.ent	alpha_ni_syscall
alpha_ni_syscall:
	.prologue 0
	/* Special because it also implements overflow handling via
	   syscall number 0.  And if you recall, zero is a special
	   trigger for "not an error".  Store large non-zero there.  */
	lda	$0, -ENOSYS
	unop
	stq	$0, 0($sp)
	ret
.end alpha_ni_syscall