aboutsummaryrefslogtreecommitdiff
path: root/arch/ia64/kernel/fsys.S
blob: 4f3cdef75797ccb4bf9949e6e0da43b1284eed17 (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
/*
 * This file contains the light-weight system call handlers (fsyscall-handlers).
 *
 * Copyright (C) 2003 Hewlett-Packard Co
 * 	David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * 25-Sep-03 davidm	Implement fsys_rt_sigprocmask().
 * 18-Feb-03 louisk	Implement fsys_gettimeofday().
 * 28-Feb-03 davidm	Fixed several bugs in fsys_gettimeofday().  Tuned it some more,
 *			probably broke it along the way... ;-)
 * 13-Jul-04 clameter   Implement fsys_clock_gettime and revise fsys_gettimeofday to make
 *                      it capable of using memory based clocks without falling back to C code.
 */

#include <asm/asmmacro.h>
#include <asm/errno.h>
#include <asm/offsets.h>
#include <asm/percpu.h>
#include <asm/thread_info.h>
#include <asm/sal.h>
#include <asm/signal.h>
#include <asm/system.h>
#include <asm/unistd.h>

#include "entry.h"

/*
 * See Documentation/ia64/fsys.txt for details on fsyscalls.
 *
 * On entry to an fsyscall handler:
 *   r10	= 0 (i.e., defaults to "successful syscall return")
 *   r11	= saved ar.pfs (a user-level value)
 *   r15	= system call number
 *   r16	= "current" task pointer (in normal kernel-mode, this is in r13)
 *   r32-r39	= system call arguments
 *   b6		= return address (a user-level value)
 *   ar.pfs	= previous frame-state (a user-level value)
 *   PSR.be	= cleared to zero (i.e., little-endian byte order is in effect)
 *   all other registers may contain values passed in from user-mode
 *
 * On return from an fsyscall handler:
 *   r11	= saved ar.pfs (as passed into the fsyscall handler)
 *   r15	= system call number (as passed into the fsyscall handler)
 *   r32-r39	= system call arguments (as passed into the fsyscall handler)
 *   b6		= return address (as passed into the fsyscall handler)
 *   ar.pfs	= previous frame-state (as passed into the fsyscall handler)
 */

ENTRY(fsys_ni_syscall)
	.prologue
	.altrp b6
	.body
	mov r8=ENOSYS
	mov r10=-1
	FSYS_RETURN
END(fsys_ni_syscall)

ENTRY(fsys_getpid)
	.prologue
	.altrp b6
	.body
	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
	;;
	ld4 r9=[r9]
	add r8=IA64_TASK_TGID_OFFSET,r16
	;;
	and r9=TIF_ALLWORK_MASK,r9
	ld4 r8=[r8]				// r8 = current->tgid
	;;
	cmp.ne p8,p0=0,r9
(p8)	br.spnt.many fsys_fallback_syscall
	FSYS_RETURN
END(fsys_getpid)

ENTRY(fsys_getppid)
	.prologue
	.altrp b6
	.body
	add r17=IA64_TASK_GROUP_LEADER_OFFSET,r16
	;;
	ld8 r17=[r17]				// r17 = current->group_leader
	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
	;;

	ld4 r9=[r9]
	add r17=IA64_TASK_REAL_PARENT_OFFSET,r17 // r17 = &current->group_leader->real_parent
	;;
	and r9=TIF_ALLWORK_MASK,r9

1:	ld8 r18=[r17]				// r18 = current->group_leader->real_parent
	;;
	cmp.ne p8,p0=0,r9
	add r8=IA64_TASK_TGID_OFFSET,r18	// r8 = &current->group_leader->real_parent->tgid
	;;

	/*
	 * The .acq is needed to ensure that the read of tgid has returned its data before
	 * we re-check "real_parent".
	 */
	ld4.acq r8=[r8]				// r8 = current->group_leader->real_parent->tgid
#ifdef CONFIG_SMP
	/*
	 * Re-read current->group_leader->real_parent.
	 */
	ld8 r19=[r17]				// r19 = current->group_leader->real_parent
(p8)	br.spnt.many fsys_fallback_syscall
	;;
	cmp.ne p6,p0=r18,r19			// did real_parent change?
	mov r19=0			// i must not leak kernel bits...
(p6)	br.cond.spnt.few 1b			// yes -> redo the read of tgid and the check
	;;
	mov r17=0			// i must not leak kernel bits...
	mov r18=0			// i must not leak kernel bits...
#else
	mov r17=0			// i must not leak kernel bits...
	mov r18=0			// i must not leak kernel bits...
	mov r19=0			// i must not leak kernel bits...
#endif
	FSYS_RETURN
END(fsys_getppid)

ENTRY(fsys_set_tid_address)
	.prologue
	.altrp b6
	.body
	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
	;;
	ld4 r9=[r9]
	tnat.z p6,p7=r32		// check argument register for being NaT
	;;
	and r9=TIF_ALLWORK_MASK,r9
	add r8=IA64_TASK_PID_OFFSET,r16
	add r18=IA64_TASK_CLEAR_CHILD_TID_OFFSET,r16
	;;
	ld4 r8=[r8]
	cmp.ne p8,p0=0,r9
	mov r17=-1
	;;
(p6)	st8 [r18]=r32
(p7)	st8 [r18]=r17
(p8)	br.spnt.many fsys_fallback_syscall
	;;
	mov r17=0			// i must not leak kernel bits...
	mov r18=0			// i must not leak kernel bits...
	FSYS_RETURN
END(fsys_set_tid_address)

/*
 * Ensure that the time interpolator structure is compatible with the asm code
 */
#if IA64_TIME_INTERPOLATOR_SOURCE_OFFSET !=0 || IA64_TIME_INTERPOLATOR_SHIFT_OFFSET != 2 \
	|| IA64_TIME_INTERPOLATOR_JITTER_OFFSET != 3 || IA64_TIME_INTERPOLATOR_NSEC_OFFSET != 4
#error fsys_gettimeofday incompatible with changes to struct time_interpolator
#endif
#define CLOCK_REALTIME 0
#define CLOCK_MONOTONIC 1
#define CLOCK_DIVIDE_BY_1000 0x4000
#define CLOCK_ADD_MONOTONIC 0x8000

ENTRY(fsys_gettimeofday)
	.prologue
	.altrp b6
	.body
	mov r31 = r32
	tnat.nz p6,p0 = r33		// guard against NaT argument
(p6)    br.cond.spnt.few .fail_einval
	mov r30 = CLOCK_DIVIDE_BY_1000
	;;
.gettime:
	// Register map
	// Incoming r31 = pointer to address where to place result
	//          r30 = flags determining how time is processed
	// r2,r3 = temp r4-r7 preserved
	// r8 = result nanoseconds
	// r9 = result seconds
	// r10 = temporary storage for clock difference
	// r11 = preserved: saved ar.pfs
	// r12 = preserved: memory stack
	// r13 = preserved: thread pointer
	// r14 = address of mask / mask
	// r15 = preserved: system call number
	// r16 = preserved: current task pointer
	// r17 = wall to monotonic use
	// r18 = time_interpolator->offset
	// r19 = address of wall_to_monotonic
	// r20 = pointer to struct time_interpolator / pointer to time_interpolator->address
	// r21 = shift factor
	// r22 = address of time interpolator->last_counter
	// r23 = address of time_interpolator->last_cycle
	// r24 = adress of time_interpolator->offset
	// r25 = last_cycle value
	// r26 = last_counter value
	// r27 = pointer to xtime
	// r28 = sequence number at the beginning of critcal section
	// r29 = address of seqlock
	// r30 = time processing flags / memory address
	// r31 = pointer to result
	// Predicates
	// p6,p7 short term use
	// p8 = timesource ar.itc
	// p9 = timesource mmio64
	// p10 = timesource mmio32
	// p11 = timesource not to be handled by asm code
	// p12 = memory time source ( = p9 | p10)
	// p13 = do cmpxchg with time_interpolator_last_cycle
	// p14 = Divide by 1000
	// p15 = Add monotonic
	//
	// Note that instructions are optimized for McKinley. McKinley can process two
	// bundles simultaneously and therefore we continuously try to feed the CPU
	// two bundles and then a stop.
	tnat.nz p6,p0 = r31	// branch deferred since it does not fit into bundle structure
	mov pr = r30,0xc000	// Set predicates according to function
	add r2 = TI_FLAGS+IA64_TASK_SIZE,r16
	movl r20 = time_interpolator
	;;
	ld8 r20 = [r20]		// get pointer to time_interpolator structure
	movl r29 = xtime_lock
	ld4 r2 = [r2]		// process work pending flags
	movl r27 = xtime
	;;	// only one bundle here
	ld8 r21 = [r20]		// first quad with control information
	and r2 = TIF_ALLWORK_MASK,r2
(p6)    br.cond.spnt.few .fail_einval	// deferred branch
	;;
	add r10 = IA64_TIME_INTERPOLATOR_ADDRESS_OFFSET,r20
	extr r3 = r21,32,32	// time_interpolator->nsec_per_cyc
	extr r8 = r21,0,16	// time_interpolator->source
	cmp.ne p6, p0 = 0, r2	// Fallback if work is scheduled
(p6)    br.cond.spnt.many fsys_fallback_syscall
	;;
	cmp.eq p8,p12 = 0,r8	// Check for cpu timer
	cmp.eq p9,p0 = 1,r8	// MMIO64 ?
	extr r2 = r21,24,8	// time_interpolator->jitter
	cmp.eq p10,p0 = 2,r8	// MMIO32 ?
	cmp.ltu p11,p0 = 2,r8	// function or other clock
(p11)	br.cond.spnt.many fsys_fallback_syscall
	;;
	setf.sig f7 = r3	// Setup for scaling of counter
(p15)	movl r19 = wall_to_monotonic
(p12)	ld8 r30 = [r10]
	cmp.ne p13,p0 = r2,r0	// need jitter compensation?
	extr r21 = r21,16,8	// shift factor
	;;
.time_redo:
	.pred.rel.mutex p8,p9,p10
	ld4.acq r28 = [r29]	// xtime_lock.sequence. Must come first for locking purposes
(p8)	mov r2 = ar.itc		// CPU_TIMER. 36 clocks latency!!!
	add r22 = IA64_TIME_INTERPOLATOR_LAST_COUNTER_OFFSET,r20
(p9)	ld8 r2 = [r30]		// readq(ti->address). Could also have latency issues..
(p10)	ld4 r2 = [r30]		// readw(ti->address)
(p13)	add r23 = IA64_TIME_INTERPOLATOR_LAST_CYCLE_OFFSET,r20
	;;			// could be removed by moving the last add upward
	ld8 r26 = [r22]		// time_interpolator->last_counter
(p13)	ld8 r25 = [r23]		// time interpolator->last_cycle
	add r24 = IA64_TIME_INTERPOLATOR_OFFSET_OFFSET,r20
(p15)	ld8 r17 = [r19],IA64_TIMESPEC_TV_NSEC_OFFSET
 	ld8 r9 = [r27],IA64_TIMESPEC_TV_NSEC_OFFSET
	add r14 = IA64_TIME_INTERPOLATOR_MASK_OFFSET, r20
	;;
	ld8 r18 = [r24]		// time_interpolator->offset
	ld8 r8 = [r27],-IA64_TIMESPEC_TV_NSEC_OFFSET	// xtime.tv_nsec
(p13)	sub r3 = r25,r2	// Diff needed before comparison (thanks davidm)
	;;
	ld8 r14 = [r14]		// time_interpolator->mask
(p13)	cmp.gt.unc p6,p7 = r3,r0	// check if it is less than last. p6,p7 cleared
	sub r10 = r2,r26	// current_counter - last_counter
	;;
(p6)	sub r10 = r25,r26	// time we got was less than last_cycle
(p7)	mov ar.ccv = r25	// more than last_cycle. Prep for cmpxchg
	;;
	and r10 = r10,r14	// Apply mask
	;;
	setf.sig f8 = r10
	nop.i 123
	;;
(p7)	cmpxchg8.rel r3 = [r23],r2,ar.ccv
EX(.fail_efault, probe.w.fault r31, 3)	// This takes 5 cycles and we have spare time
	xmpy.l f8 = f8,f7	// nsec_per_cyc*(counter-last_counter)
(p15)	add r9 = r9,r17		// Add wall to monotonic.secs to result secs
	;;
(p15)	ld8 r17 = [r19],-IA64_TIMESPEC_TV_NSEC_OFFSET
(p7)	cmp.ne p7,p0 = r25,r3	// if cmpxchg not successful redo
	// simulate tbit.nz.or p7,p0 = r28,0
	and r28 = ~1,r28	// Make sequence even to force retry if odd
	getf.sig r2 = f8
	mf
	add r8 = r8,r18		// Add time interpolator offset
	;;
	ld4 r10 = [r29]		// xtime_lock.sequence
(p15)	add r8 = r8, r17	// Add monotonic.nsecs to nsecs
	shr.u r2 = r2,r21
	;;		// overloaded 3 bundles!
	// End critical section.
	add r8 = r8,r2		// Add xtime.nsecs
	cmp4.ne.or p7,p0 = r28,r10
(p7)	br.cond.dpnt.few .time_redo	// sequence number changed ?
	// Now r8=tv->tv_nsec and r9=tv->tv_sec
	mov r10 = r0
	movl r2 = 1000000000
	add r23 = IA64_TIMESPEC_TV_NSEC_OFFSET, r31
(p14)	movl r3 = 2361183241434822607	// Prep for / 1000 hack
	;;
.time_normalize:
	mov r21 = r8
	cmp.ge p6,p0 = r8,r2
(p14)	shr.u r20 = r8, 3		// We can repeat this if necessary just wasting some time
	;;
(p14)	setf.sig f8 = r20
(p6)	sub r8 = r8,r2
(p6)	add r9 = 1,r9			// two nops before the branch.
(p14)	setf.sig f7 = r3		// Chances for repeats are 1 in 10000 for gettod
(p6)	br.cond.dpnt.few .time_normalize
	;;
	// Divided by 8 though shift. Now divide by 125
	// The compiler was able to do that with a multiply
	// and a shift and we do the same
EX(.fail_efault, probe.w.fault r23, 3)		// This also costs 5 cycles
(p14)	xmpy.hu f8 = f8, f7			// xmpy has 5 cycles latency so use it...
	;;
	mov r8 = r0
(p14)	getf.sig r2 = f8
	;;
(p14)	shr.u r21 = r2, 4
	;;
EX(.fail_efault, st8 [r31] = r9)
EX(.fail_efault, st8 [r23] = r21)
	FSYS_RETURN
.fail_einval:
	mov r8 = EINVAL
	mov r10 = -1
	FSYS_RETURN
.fail_efault:
	mov r8 = EFAULT
	mov r10 = -1
	FSYS_RETURN
END(fsys_gettimeofday)

ENTRY(fsys_clock_gettime)
	.prologue
	.altrp b6
	.body
	cmp4.ltu p6, p0 = CLOCK_MONOTONIC, r32
	// Fallback if this is not CLOCK_REALTIME or CLOCK_MONOTONIC
(p6)	br.spnt.few fsys_fallback_syscall
	mov r31 = r33
	shl r30 = r32,15
	br.many .gettime
END(fsys_clock_gettime)

/*
 * long fsys_rt_sigprocmask (int how, sigset_t *set, sigset_t *oset, size_t sigsetsize).
 */
#if _NSIG_WORDS != 1
# error Sorry, fsys_rt_sigprocmask() needs to be updated for _NSIG_WORDS != 1.
#endif
ENTRY(fsys_rt_sigprocmask)
	.prologue
	.altrp b6
	.body

	add r2=IA64_TASK_BLOCKED_OFFSET,r16
	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
	cmp4.ltu p6,p0=SIG_SETMASK,r32

	cmp.ne p15,p0=r0,r34			// oset != NULL?
	tnat.nz p8,p0=r34
	add r31=IA64_TASK_SIGHAND_OFFSET,r16
	;;
	ld8 r3=[r2]				// read/prefetch current->blocked
	ld4 r9=[r9]
	tnat.nz.or p6,p0=r35

	cmp.ne.or p6,p0=_NSIG_WORDS*8,r35
	tnat.nz.or p6,p0=r32
(p6)	br.spnt.few .fail_einval		// fail with EINVAL
	;;
#ifdef CONFIG_SMP
	ld8 r31=[r31]				// r31 <- current->sighand
#endif
	and r9=TIF_ALLWORK_MASK,r9
	tnat.nz.or p8,p0=r33
	;;
	cmp.ne p7,p0=0,r9
	cmp.eq p6,p0=r0,r33			// set == NULL?
	add r31=IA64_SIGHAND_SIGLOCK_OFFSET,r31	// r31 <- current->sighand->siglock
(p8)	br.spnt.few .fail_efault		// fail with EFAULT
(p7)	br.spnt.many fsys_fallback_syscall	// got pending kernel work...
(p6)	br.dpnt.many .store_mask		// -> short-circuit to just reading the signal mask

	/* Argh, we actually have to do some work and _update_ the signal mask: */

EX(.fail_efault, probe.r.fault r33, 3)		// verify user has read-access to *set
EX(.fail_efault, ld8 r14=[r33])			// r14 <- *set
	mov r17=(1 << (SIGKILL - 1)) | (1 << (SIGSTOP - 1))
	;;

	rsm psr.i				// mask interrupt delivery
	mov ar.ccv=0
	andcm r14=r14,r17			// filter out SIGKILL & SIGSTOP

#ifdef CONFIG_SMP
	mov r17=1
	;;
	cmpxchg4.acq r18=[r31],r17,ar.ccv	// try to acquire the lock
	mov r8=EINVAL			// default to EINVAL
	;;
	ld8 r3=[r2]			// re-read current->blocked now that we hold the lock
	cmp4.ne p6,p0=r18,r0
(p6)	br.cond.spnt.many .lock_contention
	;;
#else
	ld8 r3=[r2]			// re-read current->blocked now that we hold the lock
	mov r8=EINVAL			// default to EINVAL
#endif
	add r18=IA64_TASK_PENDING_OFFSET+IA64_SIGPENDING_SIGNAL_OFFSET,r16
	add r19=IA64_TASK_SIGNAL_OFFSET,r16
	cmp4.eq p6,p0=SIG_BLOCK,r32
	;;
	ld8 r19=[r19]			// r19 <- current->signal
	cmp4.eq p7,p0=SIG_UNBLOCK,r32
	cmp4.eq p8,p0=SIG_SETMASK,r32
	;;
	ld8 r18=[r18]			// r18 <- current->pending.signal
	.pred.rel.mutex p6,p7,p8
(p6)	or r14=r3,r14			// SIG_BLOCK
(p7)	andcm r14=r3,r14		// SIG_UNBLOCK

(p8)	mov r14=r14			// SIG_SETMASK
(p6)	mov r8=0			// clear error code
	// recalc_sigpending()
	add r17=IA64_SIGNAL_GROUP_STOP_COUNT_OFFSET,r19

	add r19=IA64_SIGNAL_SHARED_PENDING_OFFSET+IA64_SIGPENDING_SIGNAL_OFFSET,r19
	;;
	ld4 r17=[r17]		// r17 <- current->signal->group_stop_count
(p7)	mov r8=0		// clear error code

	ld8 r19=[r19]		// r19 <- current->signal->shared_pending
	;;
	cmp4.gt p6,p7=r17,r0	// p6/p7 <- (current->signal->group_stop_count > 0)?
(p8)	mov r8=0		// clear error code

	or r18=r18,r19		// r18 <- current->pending | current->signal->shared_pending
	;;
	// r18 <- (current->pending | current->signal->shared_pending) & ~current->blocked:
	andcm r18=r18,r14
	add r9=TI_FLAGS+IA64_TASK_SIZE,r16
	;;

(p7)	cmp.ne.or.andcm p6,p7=r18,r0		// p6/p7 <- signal pending
	mov r19=0					// i must not leak kernel bits...
(p6)	br.cond.dpnt.many .sig_pending
	;;

1:	ld4 r17=[r9]				// r17 <- current->thread_info->flags
	;;
	mov ar.ccv=r17
	and r18=~_TIF_SIGPENDING,r17		// r18 <- r17 & ~(1 << TIF_SIGPENDING)
	;;

	st8 [r2]=r14				// update current->blocked with new mask
	cmpxchg4.acq r14=[r9],r18,ar.ccv	// current->thread_info->flags <- r18
	;;
	cmp.ne p6,p0=r17,r14			// update failed?
(p6)	br.cond.spnt.few 1b			// yes -> retry

#ifdef CONFIG_SMP
	st4.rel [r31]=r0			// release the lock
#endif
	ssm psr.i
	;;

	srlz.d					// ensure psr.i is set again
	mov r18=0					// i must not leak kernel bits...

.store_mask:
EX(.fail_efault, (p15) probe.w.fault r34, 3)	// verify user has write-access to *oset
EX(.fail_efault, (p15) st8 [r34]=r3)
	mov r2=0					// i must not leak kernel bits...
	mov r3=0					// i must not leak kernel bits...
	mov r8=0				// return 0
	mov r9=0					// i must not leak kernel bits...
	mov r14=0					// i must not leak kernel bits...
	mov r17=0					// i must not leak kernel bits...
	mov r31=0					// i must not leak kernel bits...
	FSYS_RETURN

.sig_pending:
#ifdef CONFIG_SMP
	st4.rel [r31]=r0			// release the lock
#endif
	ssm psr.i
	;;
	srlz.d
	br.sptk.many fsys_fallback_syscall	// with signal pending, do the heavy-weight syscall

#ifdef CONFIG_SMP
.lock_contention:
	/* Rather than spinning here, fall back on doing a heavy-weight syscall.  */
	ssm psr.i
	;;
	srlz.d
	br.sptk.many fsys_fallback_syscall
#endif
END(fsys_rt_sigprocmask)

ENTRY(fsys_fallback_syscall)
	.prologue
	.altrp b6
	.body
	/*
	 * We only get here from light-weight syscall handlers.  Thus, we already
	 * know that r15 contains a valid syscall number.  No need to re-check.
	 */
	adds r17=-1024,r15
	movl r14=sys_call_table
	;;
	rsm psr.i
	shladd r18=r17,3,r14
	;;
	ld8 r18=[r18]				// load normal (heavy-weight) syscall entry-point
	mov r29=psr				// read psr (12 cyc load latency)
	mov r27=ar.rsc
	mov r21=ar.fpsr
	mov r26=ar.pfs
END(fsys_fallback_syscall)
	/* FALL THROUGH */
GLOBAL_ENTRY(fsys_bubble_down)
	.prologue
	.altrp b6
	.body
	/*
	 * We get here for syscalls that don't have a lightweight handler.  For those, we
	 * need to bubble down into the kernel and that requires setting up a minimal
	 * pt_regs structure, and initializing the CPU state more or less as if an
	 * interruption had occurred.  To make syscall-restarts work, we setup pt_regs
	 * such that cr_iip points to the second instruction in syscall_via_break.
	 * Decrementing the IP hence will restart the syscall via break and not
	 * decrementing IP will return us to the caller, as usual.  Note that we preserve
	 * the value of psr.pp rather than initializing it from dcr.pp.  This makes it
	 * possible to distinguish fsyscall execution from other privileged execution.
	 *
	 * On entry:
	 *	- normal fsyscall handler register usage, except that we also have:
	 *	- r18: address of syscall entry point
	 *	- r21: ar.fpsr
	 *	- r26: ar.pfs
	 *	- r27: ar.rsc
	 *	- r29: psr
	 */
#	define PSR_PRESERVED_BITS	(IA64_PSR_UP | IA64_PSR_MFL | IA64_PSR_MFH | IA64_PSR_PK \
					 | IA64_PSR_DT | IA64_PSR_PP | IA64_PSR_SP | IA64_PSR_RT \
					 | IA64_PSR_IC)
	/*
	 * Reading psr.l gives us only bits 0-31, psr.it, and psr.mc.  The rest we have
	 * to synthesize.
	 */
#	define PSR_ONE_BITS		((3 << IA64_PSR_CPL0_BIT) | (0x1 << IA64_PSR_RI_BIT) \
					 | IA64_PSR_BN | IA64_PSR_I)

	invala
	movl r8=PSR_ONE_BITS

	mov r25=ar.unat			// save ar.unat (5 cyc)
	movl r9=PSR_PRESERVED_BITS

	mov ar.rsc=0			// set enforced lazy mode, pl 0, little-endian, loadrs=0
	movl r28=__kernel_syscall_via_break
	;;
	mov r23=ar.bspstore		// save ar.bspstore (12 cyc)
	mov r31=pr			// save pr (2 cyc)
	mov r20=r1			// save caller's gp in r20
	;;
	mov r2=r16			// copy current task addr to addl-addressable register
	and r9=r9,r29
	mov r19=b6			// save b6 (2 cyc)
	;;
	mov psr.l=r9			// slam the door (17 cyc to srlz.i)
	or r29=r8,r29			// construct cr.ipsr value to save
	addl r22=IA64_RBS_OFFSET,r2	// compute base of RBS
	;;
	// GAS reports a spurious RAW hazard on the read of ar.rnat because it thinks
	// we may be reading ar.itc after writing to psr.l.  Avoid that message with
	// this directive:
	dv_serialize_data
	mov.m r24=ar.rnat		// read ar.rnat (5 cyc lat)
	lfetch.fault.excl.nt1 [r22]
	adds r16=IA64_TASK_THREAD_ON_USTACK_OFFSET,r2

	// ensure previous insn group is issued before we stall for srlz.i:
	;;
	srlz.i				// ensure new psr.l has been established
	/////////////////////////////////////////////////////////////////////////////
	////////// from this point on, execution is not interruptible anymore
	/////////////////////////////////////////////////////////////////////////////
	addl r1=IA64_STK_OFFSET-IA64_PT_REGS_SIZE,r2	// compute base of memory stack
	cmp.ne pKStk,pUStk=r0,r0	// set pKStk <- 0, pUStk <- 1
	;;
	st1 [r16]=r0			// clear current->thread.on_ustack flag
	mov ar.bspstore=r22		// switch to kernel RBS
	mov b6=r18			// copy syscall entry-point to b6 (7 cyc)
	add r3=TI_FLAGS+IA64_TASK_SIZE,r2
	;;
	ld4 r3=[r3]				// r2 = current_thread_info()->flags
	mov r18=ar.bsp			// save (kernel) ar.bsp (12 cyc)
	mov ar.rsc=0x3			// set eager mode, pl 0, little-endian, loadrs=0
	br.call.sptk.many b7=ia64_syscall_setup
	;;
	ssm psr.i
	movl r2=ia64_ret_from_syscall
	;;
	mov rp=r2				// set the real return addr
	and r3=_TIF_SYSCALL_TRACEAUDIT,r3
	;;
	cmp.eq p8,p0=r3,r0

(p10)	br.cond.spnt.many ia64_ret_from_syscall	// p10==true means out registers are more than 8
(p8)	br.call.sptk.many b6=b6		// ignore this return addr
	br.cond.sptk ia64_trace_syscall
END(fsys_bubble_down)

	.rodata
	.align 8
	.globl fsyscall_table

	data8 fsys_bubble_down
fsyscall_table:
	data8 fsys_ni_syscall
	data8 0				// exit			// 1025
	data8 0				// read
	data8 0				// write
	data8 0				// open
	data8 0				// close
	data8 0				// creat		// 1030
	data8 0				// link
	data8 0				// unlink
	data8 0				// execve
	data8 0				// chdir
	data8 0				// fchdir		// 1035
	data8 0				// utimes
	data8 0				// mknod
	data8 0				// chmod
	data8 0				// chown
	data8 0				// lseek		// 1040
	data8 fsys_getpid		// getpid
	data8 fsys_getppid		// getppid
	data8 0				// mount
	data8 0				// umount
	data8 0				// setuid		// 1045
	data8 0				// getuid
	data8 0				// geteuid
	data8 0				// ptrace
	data8 0				// access
	data8 0				// sync			// 1050
	data8 0				// fsync
	data8 0				// fdatasync
	data8 0				// kill
	data8 0				// rename
	data8 0				// mkdir		// 1055
	data8 0				// rmdir
	data8 0				// dup
	data8 0				// pipe
	data8 0				// times
	data8 0				// brk			// 1060
	data8 0				// setgid
	data8 0				// getgid
	data8 0				// getegid
	data8 0				// acct
	data8 0				// ioctl		// 1065
	data8 0				// fcntl
	data8 0				// umask
	data8 0				// chroot
	data8 0				// ustat
	data8 0				// dup2			// 1070
	data8 0				// setreuid
	data8 0				// setregid
	data8 0				// getresuid
	data8 0				// setresuid
	data8 0				// getresgid		// 1075
	data8 0				// setresgid
	data8 0				// getgroups
	data8 0				// setgroups
	data8 0				// getpgid
	data8 0				// setpgid		// 1080
	data8 0				// setsid
	data8 0				// getsid
	data8 0				// sethostname
	data8 0				// setrlimit
	data8 0				// getrlimit		// 1085
	data8 0				// getrusage
	data8 fsys_gettimeofday		// gettimeofday
	data8 0				// settimeofday
	data8 0				// select
	data8 0				// poll			// 1090
	data8 0				// symlink
	data8 0				// readlink
	data8 0				// uselib
	data8 0				// swapon
	data8 0				// swapoff		// 1095
	data8 0				// reboot
	data8 0				// truncate
	data8 0				// ftruncate
	data8 0				// fchmod
	data8 0				// fchown		// 1100
	data8 0				// getpriority
	data8 0				// setpriority
	data8 0				// statfs
	data8 0				// fstatfs
	data8 0				// gettid		// 1105
	data8 0				// semget
	data8 0				// semop
	data8 0				// semctl
	data8 0				// msgget
	data8 0				// msgsnd		// 1110
	data8 0				// msgrcv
	data8 0				// msgctl
	data8 0				// shmget
	data8 0				// shmat
	data8 0				// shmdt		// 1115
	data8 0				// shmctl
	data8 0				// syslog
	data8 0				// setitimer
	data8 0				// getitimer
	data8 0					 		// 1120
	data8 0
	data8 0
	data8 0				// vhangup
	data8 0				// lchown
	data8 0				// remap_file_pages	// 1125
	data8 0				// wait4
	data8 0				// sysinfo
	data8 0				// clone
	data8 0				// setdomainname
	data8 0				// newuname		// 1130
	data8 0				// adjtimex
	data8 0
	data8 0				// init_module
	data8 0				// delete_module
	data8 0							// 1135
	data8 0
	data8 0				// quotactl
	data8 0				// bdflush
	data8 0				// sysfs
	data8 0				// personality		// 1140
	data8 0				// afs_syscall
	data8 0				// setfsuid
	data8 0				// setfsgid
	data8 0				// getdents
	data8 0				// flock		// 1145
	data8 0				// readv
	data8 0				// writev
	data8 0				// pread64
	data8 0				// pwrite64
	data8 0				// sysctl		// 1150
	data8 0				// mmap
	data8 0				// munmap
	data8 0				// mlock
	data8 0				// mlockall
	data8 0				// mprotect		// 1155
	data8 0				// mremap
	data8 0				// msync
	data8 0				// munlock
	data8 0				// munlockall
	data8 0				// sched_getparam	// 1160
	data8 0				// sched_setparam
	data8 0				// sched_getscheduler
	data8 0				// sched_setscheduler
	data8 0				// sched_yield
	data8 0				// sched_get_priority_max	// 1165
	data8 0				// sched_get_priority_min
	data8 0				// sched_rr_get_interval
	data8 0				// nanosleep
	data8 0				// nfsservctl
	data8 0				// prctl		// 1170
	data8 0				// getpagesize
	data8 0				// mmap2
	data8 0				// pciconfig_read
	data8 0				// pciconfig_write
	data8 0				// perfmonctl		// 1175
	data8 0				// sigaltstack
	data8 0				// rt_sigaction
	data8 0				// rt_sigpending
	data8 fsys_rt_sigprocmask	// rt_sigprocmask
	data8 0				// rt_sigqueueinfo	// 1180
	data8 0				// rt_sigreturn
	data8 0				// rt_sigsuspend
	data8 0				// rt_sigtimedwait
	data8 0				// getcwd
	data8 0				// capget		// 1185
	data8 0				// capset
	data8 0				// sendfile
	data8 0
	data8 0
	data8 0				// socket		// 1190
	data8 0				// bind
	data8 0				// connect
	data8 0				// listen
	data8 0				// accept
	data8 0				// getsockname		// 1195
	data8 0				// getpeername
	data8 0				// socketpair
	data8 0				// send
	data8 0				// sendto
	data8 0				// recv			// 1200
	data8 0				// recvfrom
	data8 0				// shutdown
	data8 0				// setsockopt
	data8 0				// getsockopt
	data8 0				// sendmsg		// 1205
	data8 0				// recvmsg
	data8 0				// pivot_root
	data8 0				// mincore
	data8 0				// madvise
	data8 0				// newstat		// 1210
	data8 0				// newlstat
	data8 0				// newfstat
	data8 0				// clone2
	data8 0				// getdents64
	data8 0				// getunwind		// 1215
	data8 0				// readahead
	data8 0				// setxattr
	data8 0				// lsetxattr
	data8 0				// fsetxattr
	data8 0				// getxattr		// 1220
	data8 0				// lgetxattr
	data8 0				// fgetxattr
	data8 0				// listxattr
	data8 0				// llistxattr
	data8 0				// flistxattr		// 1225
	data8 0				// removexattr
	data8 0				// lremovexattr
	data8 0				// fremovexattr
	data8 0				// tkill
	data8 0				// futex		// 1230
	data8 0				// sched_setaffinity
	data8 0				// sched_getaffinity
	data8 fsys_set_tid_address	// set_tid_address
	data8 0				// fadvise64_64
	data8 0				// tgkill		// 1235
	data8 0				// exit_group
	data8 0				// lookup_dcookie
	data8 0				// io_setup
	data8 0				// io_destroy
	data8 0				// io_getevents		// 1240
	data8 0				// io_submit
	data8 0				// io_cancel
	data8 0				// epoll_create
	data8 0				// epoll_ctl
	data8 0				// epoll_wait		// 1245
	data8 0				// restart_syscall
	data8 0				// semtimedop
	data8 0				// timer_create
	data8 0				// timer_settime
	data8 0				// timer_gettime 	// 1250
	data8 0				// timer_getoverrun
	data8 0				// timer_delete
	data8 0				// clock_settime
	data8 fsys_clock_gettime	// clock_gettime
	data8 0				// clock_getres		// 1255
	data8 0				// clock_nanosleep
	data8 0				// fstatfs64
	data8 0				// statfs64
	data8 0
	data8 0							// 1260
	data8 0
	data8 0				// mq_open
	data8 0				// mq_unlink
	data8 0				// mq_timedsend
	data8 0				// mq_timedreceive	// 1265
	data8 0				// mq_notify
	data8 0				// mq_getsetattr
	data8 0				// kexec_load
	data8 0
	data8 0							// 1270
	data8 0
	data8 0
	data8 0
	data8 0
	data8 0							// 1275
	data8 0
	data8 0
	data8 0
	data8 0

	.org fsyscall_table + 8*NR_syscalls	// guard against failures to increase NR_syscalls