summaryrefslogtreecommitdiffstats
path: root/sys/amd64/amd64/fpu.c
blob: 540966b9e85903de1aec3deb076ef10ebb86cc4a (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
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
/*-
 * Copyright (c) 1990 William Jolitz.
 * Copyright (c) 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from: @(#)npx.c	7.2 (Berkeley) 5/12/91
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include <sys/signalvar.h>
#include <vm/uma.h>

#include <machine/cputypes.h>
#include <machine/frame.h>
#include <machine/intr_machdep.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/psl.h>
#include <machine/resource.h>
#include <machine/specialreg.h>
#include <machine/segments.h>
#include <machine/ucontext.h>

/*
 * Floating point support.
 */

#if defined(__GNUCLIKE_ASM) && !defined(lint)

#define	fldcw(cw)		__asm __volatile("fldcw %0" : : "m" (cw))
#define	fnclex()		__asm __volatile("fnclex")
#define	fninit()		__asm __volatile("fninit")
#define	fnstcw(addr)		__asm __volatile("fnstcw %0" : "=m" (*(addr)))
#define	fnstsw(addr)		__asm __volatile("fnstsw %0" : "=am" (*(addr)))
#define	fxrstor(addr)		__asm __volatile("fxrstor %0" : : "m" (*(addr)))
#define	fxsave(addr)		__asm __volatile("fxsave %0" : "=m" (*(addr)))
#define	ldmxcsr(csr)		__asm __volatile("ldmxcsr %0" : : "m" (csr))
#define	stmxcsr(addr)		__asm __volatile("stmxcsr %0" : : "m" (*(addr)))

static __inline void
xrstor(char *addr, uint64_t mask)
{
	uint32_t low, hi;

	low = mask;
	hi = mask >> 32;
	__asm __volatile("xrstor %0" : : "m" (*addr), "a" (low), "d" (hi));
}

static __inline void
xsave(char *addr, uint64_t mask)
{
	uint32_t low, hi;

	low = mask;
	hi = mask >> 32;
	__asm __volatile("xsave %0" : "=m" (*addr) : "a" (low), "d" (hi) :
	    "memory");
}

#else	/* !(__GNUCLIKE_ASM && !lint) */

void	fldcw(u_short cw);
void	fnclex(void);
void	fninit(void);
void	fnstcw(caddr_t addr);
void	fnstsw(caddr_t addr);
void	fxsave(caddr_t addr);
void	fxrstor(caddr_t addr);
void	ldmxcsr(u_int csr);
void	stmxcsr(u_int *csr);
void	xrstor(char *addr, uint64_t mask);
void	xsave(char *addr, uint64_t mask);

#endif	/* __GNUCLIKE_ASM && !lint */

#define	start_emulating()	load_cr0(rcr0() | CR0_TS)
#define	stop_emulating()	clts()

CTASSERT(sizeof(struct savefpu) == 512);
CTASSERT(sizeof(struct xstate_hdr) == 64);
CTASSERT(sizeof(struct savefpu_ymm) == 832);

/*
 * This requirement is to make it easier for asm code to calculate
 * offset of the fpu save area from the pcb address. FPU save area
 * must be 64-byte aligned.
 */
CTASSERT(sizeof(struct pcb) % XSAVE_AREA_ALIGN == 0);

/*
 * Ensure the copy of XCR0 saved in a core is contained in the padding
 * area.
 */
CTASSERT(X86_XSTATE_XCR0_OFFSET >= offsetof(struct savefpu, sv_pad) &&
    X86_XSTATE_XCR0_OFFSET + sizeof(uint64_t) <= sizeof(struct savefpu));

static	void	fpu_clean_state(void);

SYSCTL_INT(_hw, HW_FLOATINGPT, floatingpoint, CTLFLAG_RD,
    SYSCTL_NULL_INT_PTR, 1, "Floating point instructions executed in hardware");

int use_xsave;			/* non-static for cpu_switch.S */
uint64_t xsave_mask;		/* the same */
static	uma_zone_t fpu_save_area_zone;
static	struct savefpu *fpu_initialstate;

struct xsave_area_elm_descr {
	u_int	offset;
	u_int	size;
} *xsave_area_desc;

void
fpusave(void *addr)
{

	if (use_xsave)
		xsave((char *)addr, xsave_mask);
	else
		fxsave((char *)addr);
}

void
fpurestore(void *addr)
{

	if (use_xsave)
		xrstor((char *)addr, xsave_mask);
	else
		fxrstor((char *)addr);
}

void
fpususpend(void *addr)
{
	u_long cr0;

	cr0 = rcr0();
	stop_emulating();
	fpusave(addr);
	load_cr0(cr0);
}

void
fpuresume(void *addr)
{
	u_long cr0;

	cr0 = rcr0();
	stop_emulating();
	fninit();
	if (use_xsave)
		load_xcr(XCR0, xsave_mask);
	fpurestore(addr);
	load_cr0(cr0);
}

/*
 * Enable XSAVE if supported and allowed by user.
 * Calculate the xsave_mask.
 */
static void
fpuinit_bsp1(void)
{
	u_int cp[4];
	uint64_t xsave_mask_user;

	if ((cpu_feature2 & CPUID2_XSAVE) != 0) {
		use_xsave = 1;
		TUNABLE_INT_FETCH("hw.use_xsave", &use_xsave);
	}
	if (!use_xsave)
		return;

	cpuid_count(0xd, 0x0, cp);
	xsave_mask = XFEATURE_ENABLED_X87 | XFEATURE_ENABLED_SSE;
	if ((cp[0] & xsave_mask) != xsave_mask)
		panic("CPU0 does not support X87 or SSE: %x", cp[0]);
	xsave_mask = ((uint64_t)cp[3] << 32) | cp[0];
	xsave_mask_user = xsave_mask;
	TUNABLE_ULONG_FETCH("hw.xsave_mask", &xsave_mask_user);
	xsave_mask_user |= XFEATURE_ENABLED_X87 | XFEATURE_ENABLED_SSE;
	xsave_mask &= xsave_mask_user;
	if ((xsave_mask & XFEATURE_AVX512) != XFEATURE_AVX512)
		xsave_mask &= ~XFEATURE_AVX512;
	if ((xsave_mask & XFEATURE_MPX) != XFEATURE_MPX)
		xsave_mask &= ~XFEATURE_MPX;

	cpuid_count(0xd, 0x1, cp);
	if ((cp[0] & CPUID_EXTSTATE_XSAVEOPT) != 0) {
		/*
		 * Patch the XSAVE instruction in the cpu_switch code
		 * to XSAVEOPT.  We assume that XSAVE encoding used
		 * REX byte, and set the bit 4 of the r/m byte.
		 */
		ctx_switch_xsave[3] |= 0x10;
	}
}

/*
 * Calculate the fpu save area size.
 */
static void
fpuinit_bsp2(void)
{
	u_int cp[4];

	if (use_xsave) {
		cpuid_count(0xd, 0x0, cp);
		cpu_max_ext_state_size = cp[1];

		/*
		 * Reload the cpu_feature2, since we enabled OSXSAVE.
		 */
		do_cpuid(1, cp);
		cpu_feature2 = cp[2];
	} else
		cpu_max_ext_state_size = sizeof(struct savefpu);
}

/*
 * Initialize the floating point unit.
 */
void
fpuinit(void)
{
	register_t saveintr;
	u_int mxcsr;
	u_short control;

	if (IS_BSP())
		fpuinit_bsp1();

	if (use_xsave) {
		load_cr4(rcr4() | CR4_XSAVE);
		load_xcr(XCR0, xsave_mask);
	}

	/*
	 * XCR0 shall be set up before CPU can report the save area size.
	 */
	if (IS_BSP())
		fpuinit_bsp2();

	/*
	 * It is too early for critical_enter() to work on AP.
	 */
	saveintr = intr_disable();
	stop_emulating();
	fninit();
	control = __INITIAL_FPUCW__;
	fldcw(control);
	mxcsr = __INITIAL_MXCSR__;
	ldmxcsr(mxcsr);
	start_emulating();
	intr_restore(saveintr);
}

/*
 * On the boot CPU we generate a clean state that is used to
 * initialize the floating point unit when it is first used by a
 * process.
 */
static void
fpuinitstate(void *arg __unused)
{
	register_t saveintr;
	int cp[4], i, max_ext_n;

	fpu_initialstate = malloc(cpu_max_ext_state_size, M_DEVBUF,
	    M_WAITOK | M_ZERO);
	saveintr = intr_disable();
	stop_emulating();

	fpusave(fpu_initialstate);
	if (fpu_initialstate->sv_env.en_mxcsr_mask)
		cpu_mxcsr_mask = fpu_initialstate->sv_env.en_mxcsr_mask;
	else
		cpu_mxcsr_mask = 0xFFBF;

	/*
	 * The fninit instruction does not modify XMM registers or x87
	 * registers (MM/ST).  The fpusave call dumped the garbage
	 * contained in the registers after reset to the initial state
	 * saved.  Clear XMM and x87 registers file image to make the
	 * startup program state and signal handler XMM/x87 register
	 * content predictable.
	 */
	bzero(fpu_initialstate->sv_fp, sizeof(fpu_initialstate->sv_fp));
	bzero(fpu_initialstate->sv_xmm, sizeof(fpu_initialstate->sv_xmm));

	/*
	 * Create a table describing the layout of the CPU Extended
	 * Save Area.
	 */
	if (use_xsave) {
		max_ext_n = flsl(xsave_mask);
		xsave_area_desc = malloc(max_ext_n * sizeof(struct
		    xsave_area_elm_descr), M_DEVBUF, M_WAITOK | M_ZERO);
		/* x87 state */
		xsave_area_desc[0].offset = 0;
		xsave_area_desc[0].size = 160;
		/* XMM */
		xsave_area_desc[1].offset = 160;
		xsave_area_desc[1].size = 288 - 160;

		for (i = 2; i < max_ext_n; i++) {
			cpuid_count(0xd, i, cp);
			xsave_area_desc[i].offset = cp[1];
			xsave_area_desc[i].size = cp[0];
		}
	}

	fpu_save_area_zone = uma_zcreate("FPU_save_area",
	    cpu_max_ext_state_size, NULL, NULL, NULL, NULL,
	    XSAVE_AREA_ALIGN - 1, 0);

	start_emulating();
	intr_restore(saveintr);
}
SYSINIT(fpuinitstate, SI_SUB_DRIVERS, SI_ORDER_ANY, fpuinitstate, NULL);

/*
 * Free coprocessor (if we have it).
 */
void
fpuexit(struct thread *td)
{

	critical_enter();
	if (curthread == PCPU_GET(fpcurthread)) {
		stop_emulating();
		fpusave(curpcb->pcb_save);
		start_emulating();
		PCPU_SET(fpcurthread, NULL);
	}
	critical_exit();
}

int
fpuformat(void)
{

	return (_MC_FPFMT_XMM);
}

/* 
 * The following mechanism is used to ensure that the FPE_... value
 * that is passed as a trapcode to the signal handler of the user
 * process does not have more than one bit set.
 * 
 * Multiple bits may be set if the user process modifies the control
 * word while a status word bit is already set.  While this is a sign
 * of bad coding, we have no choise than to narrow them down to one
 * bit, since we must not send a trapcode that is not exactly one of
 * the FPE_ macros.
 *
 * The mechanism has a static table with 127 entries.  Each combination
 * of the 7 FPU status word exception bits directly translates to a
 * position in this table, where a single FPE_... value is stored.
 * This FPE_... value stored there is considered the "most important"
 * of the exception bits and will be sent as the signal code.  The
 * precedence of the bits is based upon Intel Document "Numerical
 * Applications", Chapter "Special Computational Situations".
 *
 * The macro to choose one of these values does these steps: 1) Throw
 * away status word bits that cannot be masked.  2) Throw away the bits
 * currently masked in the control word, assuming the user isn't
 * interested in them anymore.  3) Reinsert status word bit 7 (stack
 * fault) if it is set, which cannot be masked but must be presered.
 * 4) Use the remaining bits to point into the trapcode table.
 *
 * The 6 maskable bits in order of their preference, as stated in the
 * above referenced Intel manual:
 * 1  Invalid operation (FP_X_INV)
 * 1a   Stack underflow
 * 1b   Stack overflow
 * 1c   Operand of unsupported format
 * 1d   SNaN operand.
 * 2  QNaN operand (not an exception, irrelavant here)
 * 3  Any other invalid-operation not mentioned above or zero divide
 *      (FP_X_INV, FP_X_DZ)
 * 4  Denormal operand (FP_X_DNML)
 * 5  Numeric over/underflow (FP_X_OFL, FP_X_UFL)
 * 6  Inexact result (FP_X_IMP) 
 */
static char fpetable[128] = {
	0,
	FPE_FLTINV,	/*  1 - INV */
	FPE_FLTUND,	/*  2 - DNML */
	FPE_FLTINV,	/*  3 - INV | DNML */
	FPE_FLTDIV,	/*  4 - DZ */
	FPE_FLTINV,	/*  5 - INV | DZ */
	FPE_FLTDIV,	/*  6 - DNML | DZ */
	FPE_FLTINV,	/*  7 - INV | DNML | DZ */
	FPE_FLTOVF,	/*  8 - OFL */
	FPE_FLTINV,	/*  9 - INV | OFL */
	FPE_FLTUND,	/*  A - DNML | OFL */
	FPE_FLTINV,	/*  B - INV | DNML | OFL */
	FPE_FLTDIV,	/*  C - DZ | OFL */
	FPE_FLTINV,	/*  D - INV | DZ | OFL */
	FPE_FLTDIV,	/*  E - DNML | DZ | OFL */
	FPE_FLTINV,	/*  F - INV | DNML | DZ | OFL */
	FPE_FLTUND,	/* 10 - UFL */
	FPE_FLTINV,	/* 11 - INV | UFL */
	FPE_FLTUND,	/* 12 - DNML | UFL */
	FPE_FLTINV,	/* 13 - INV | DNML | UFL */
	FPE_FLTDIV,	/* 14 - DZ | UFL */
	FPE_FLTINV,	/* 15 - INV | DZ | UFL */
	FPE_FLTDIV,	/* 16 - DNML | DZ | UFL */
	FPE_FLTINV,	/* 17 - INV | DNML | DZ | UFL */
	FPE_FLTOVF,	/* 18 - OFL | UFL */
	FPE_FLTINV,	/* 19 - INV | OFL | UFL */
	FPE_FLTUND,	/* 1A - DNML | OFL | UFL */
	FPE_FLTINV,	/* 1B - INV | DNML | OFL | UFL */
	FPE_FLTDIV,	/* 1C - DZ | OFL | UFL */
	FPE_FLTINV,	/* 1D - INV | DZ | OFL | UFL */
	FPE_FLTDIV,	/* 1E - DNML | DZ | OFL | UFL */
	FPE_FLTINV,	/* 1F - INV | DNML | DZ | OFL | UFL */
	FPE_FLTRES,	/* 20 - IMP */
	FPE_FLTINV,	/* 21 - INV | IMP */
	FPE_FLTUND,	/* 22 - DNML | IMP */
	FPE_FLTINV,	/* 23 - INV | DNML | IMP */
	FPE_FLTDIV,	/* 24 - DZ | IMP */
	FPE_FLTINV,	/* 25 - INV | DZ | IMP */
	FPE_FLTDIV,	/* 26 - DNML | DZ | IMP */
	FPE_FLTINV,	/* 27 - INV | DNML | DZ | IMP */
	FPE_FLTOVF,	/* 28 - OFL | IMP */
	FPE_FLTINV,	/* 29 - INV | OFL | IMP */
	FPE_FLTUND,	/* 2A - DNML | OFL | IMP */
	FPE_FLTINV,	/* 2B - INV | DNML | OFL | IMP */
	FPE_FLTDIV,	/* 2C - DZ | OFL | IMP */
	FPE_FLTINV,	/* 2D - INV | DZ | OFL | IMP */
	FPE_FLTDIV,	/* 2E - DNML | DZ | OFL | IMP */
	FPE_FLTINV,	/* 2F - INV | DNML | DZ | OFL | IMP */
	FPE_FLTUND,	/* 30 - UFL | IMP */
	FPE_FLTINV,	/* 31 - INV | UFL | IMP */
	FPE_FLTUND,	/* 32 - DNML | UFL | IMP */
	FPE_FLTINV,	/* 33 - INV | DNML | UFL | IMP */
	FPE_FLTDIV,	/* 34 - DZ | UFL | IMP */
	FPE_FLTINV,	/* 35 - INV | DZ | UFL | IMP */
	FPE_FLTDIV,	/* 36 - DNML | DZ | UFL | IMP */
	FPE_FLTINV,	/* 37 - INV | DNML | DZ | UFL | IMP */
	FPE_FLTOVF,	/* 38 - OFL | UFL | IMP */
	FPE_FLTINV,	/* 39 - INV | OFL | UFL | IMP */
	FPE_FLTUND,	/* 3A - DNML | OFL | UFL | IMP */
	FPE_FLTINV,	/* 3B - INV | DNML | OFL | UFL | IMP */
	FPE_FLTDIV,	/* 3C - DZ | OFL | UFL | IMP */
	FPE_FLTINV,	/* 3D - INV | DZ | OFL | UFL | IMP */
	FPE_FLTDIV,	/* 3E - DNML | DZ | OFL | UFL | IMP */
	FPE_FLTINV,	/* 3F - INV | DNML | DZ | OFL | UFL | IMP */
	FPE_FLTSUB,	/* 40 - STK */
	FPE_FLTSUB,	/* 41 - INV | STK */
	FPE_FLTUND,	/* 42 - DNML | STK */
	FPE_FLTSUB,	/* 43 - INV | DNML | STK */
	FPE_FLTDIV,	/* 44 - DZ | STK */
	FPE_FLTSUB,	/* 45 - INV | DZ | STK */
	FPE_FLTDIV,	/* 46 - DNML | DZ | STK */
	FPE_FLTSUB,	/* 47 - INV | DNML | DZ | STK */
	FPE_FLTOVF,	/* 48 - OFL | STK */
	FPE_FLTSUB,	/* 49 - INV | OFL | STK */
	FPE_FLTUND,	/* 4A - DNML | OFL | STK */
	FPE_FLTSUB,	/* 4B - INV | DNML | OFL | STK */
	FPE_FLTDIV,	/* 4C - DZ | OFL | STK */
	FPE_FLTSUB,	/* 4D - INV | DZ | OFL | STK */
	FPE_FLTDIV,	/* 4E - DNML | DZ | OFL | STK */
	FPE_FLTSUB,	/* 4F - INV | DNML | DZ | OFL | STK */
	FPE_FLTUND,	/* 50 - UFL | STK */
	FPE_FLTSUB,	/* 51 - INV | UFL | STK */
	FPE_FLTUND,	/* 52 - DNML | UFL | STK */
	FPE_FLTSUB,	/* 53 - INV | DNML | UFL | STK */
	FPE_FLTDIV,	/* 54 - DZ | UFL | STK */
	FPE_FLTSUB,	/* 55 - INV | DZ | UFL | STK */
	FPE_FLTDIV,	/* 56 - DNML | DZ | UFL | STK */
	FPE_FLTSUB,	/* 57 - INV | DNML | DZ | UFL | STK */
	FPE_FLTOVF,	/* 58 - OFL | UFL | STK */
	FPE_FLTSUB,	/* 59 - INV | OFL | UFL | STK */
	FPE_FLTUND,	/* 5A - DNML | OFL | UFL | STK */
	FPE_FLTSUB,	/* 5B - INV | DNML | OFL | UFL | STK */
	FPE_FLTDIV,	/* 5C - DZ | OFL | UFL | STK */
	FPE_FLTSUB,	/* 5D - INV | DZ | OFL | UFL | STK */
	FPE_FLTDIV,	/* 5E - DNML | DZ | OFL | UFL | STK */
	FPE_FLTSUB,	/* 5F - INV | DNML | DZ | OFL | UFL | STK */
	FPE_FLTRES,	/* 60 - IMP | STK */
	FPE_FLTSUB,	/* 61 - INV | IMP | STK */
	FPE_FLTUND,	/* 62 - DNML | IMP | STK */
	FPE_FLTSUB,	/* 63 - INV | DNML | IMP | STK */
	FPE_FLTDIV,	/* 64 - DZ | IMP | STK */
	FPE_FLTSUB,	/* 65 - INV | DZ | IMP | STK */
	FPE_FLTDIV,	/* 66 - DNML | DZ | IMP | STK */
	FPE_FLTSUB,	/* 67 - INV | DNML | DZ | IMP | STK */
	FPE_FLTOVF,	/* 68 - OFL | IMP | STK */
	FPE_FLTSUB,	/* 69 - INV | OFL | IMP | STK */
	FPE_FLTUND,	/* 6A - DNML | OFL | IMP | STK */
	FPE_FLTSUB,	/* 6B - INV | DNML | OFL | IMP | STK */
	FPE_FLTDIV,	/* 6C - DZ | OFL | IMP | STK */
	FPE_FLTSUB,	/* 6D - INV | DZ | OFL | IMP | STK */
	FPE_FLTDIV,	/* 6E - DNML | DZ | OFL | IMP | STK */
	FPE_FLTSUB,	/* 6F - INV | DNML | DZ | OFL | IMP | STK */
	FPE_FLTUND,	/* 70 - UFL | IMP | STK */
	FPE_FLTSUB,	/* 71 - INV | UFL | IMP | STK */
	FPE_FLTUND,	/* 72 - DNML | UFL | IMP | STK */
	FPE_FLTSUB,	/* 73 - INV | DNML | UFL | IMP | STK */
	FPE_FLTDIV,	/* 74 - DZ | UFL | IMP | STK */
	FPE_FLTSUB,	/* 75 - INV | DZ | UFL | IMP | STK */
	FPE_FLTDIV,	/* 76 - DNML | DZ | UFL | IMP | STK */
	FPE_FLTSUB,	/* 77 - INV | DNML | DZ | UFL | IMP | STK */
	FPE_FLTOVF,	/* 78 - OFL | UFL | IMP | STK */
	FPE_FLTSUB,	/* 79 - INV | OFL | UFL | IMP | STK */
	FPE_FLTUND,	/* 7A - DNML | OFL | UFL | IMP | STK */
	FPE_FLTSUB,	/* 7B - INV | DNML | OFL | UFL | IMP | STK */
	FPE_FLTDIV,	/* 7C - DZ | OFL | UFL | IMP | STK */
	FPE_FLTSUB,	/* 7D - INV | DZ | OFL | UFL | IMP | STK */
	FPE_FLTDIV,	/* 7E - DNML | DZ | OFL | UFL | IMP | STK */
	FPE_FLTSUB,	/* 7F - INV | DNML | DZ | OFL | UFL | IMP | STK */
};

/*
 * Read the FP status and control words, then generate si_code value
 * for SIGFPE.  The error code chosen will be one of the
 * FPE_... macros.  It will be sent as the second argument to old
 * BSD-style signal handlers and as "siginfo_t->si_code" (second
 * argument) to SA_SIGINFO signal handlers.
 *
 * Some time ago, we cleared the x87 exceptions with FNCLEX there.
 * Clearing exceptions was necessary mainly to avoid IRQ13 bugs.  The
 * usermode code which understands the FPU hardware enough to enable
 * the exceptions, can also handle clearing the exception state in the
 * handler.  The only consequence of not clearing the exception is the
 * rethrow of the SIGFPE on return from the signal handler and
 * reexecution of the corresponding instruction.
 *
 * For XMM traps, the exceptions were never cleared.
 */
int
fputrap_x87(void)
{
	struct savefpu *pcb_save;
	u_short control, status;

	critical_enter();

	/*
	 * Interrupt handling (for another interrupt) may have pushed the
	 * state to memory.  Fetch the relevant parts of the state from
	 * wherever they are.
	 */
	if (PCPU_GET(fpcurthread) != curthread) {
		pcb_save = curpcb->pcb_save;
		control = pcb_save->sv_env.en_cw;
		status = pcb_save->sv_env.en_sw;
	} else {
		fnstcw(&control);
		fnstsw(&status);
	}

	critical_exit();
	return (fpetable[status & ((~control & 0x3f) | 0x40)]);
}

int
fputrap_sse(void)
{
	u_int mxcsr;

	critical_enter();
	if (PCPU_GET(fpcurthread) != curthread)
		mxcsr = curpcb->pcb_save->sv_env.en_mxcsr;
	else
		stmxcsr(&mxcsr);
	critical_exit();
	return (fpetable[(mxcsr & (~mxcsr >> 7)) & 0x3f]);
}

/*
 * Device Not Available (DNA, #NM) exception handler.
 *
 * It would be better to switch FP context here (if curthread !=
 * fpcurthread) and not necessarily for every context switch, but it
 * is too hard to access foreign pcb's.
 */
void
fpudna(void)
{

	/*
	 * This handler is entered with interrupts enabled, so context
	 * switches may occur before critical_enter() is executed.  If
	 * a context switch occurs, then when we regain control, our
	 * state will have been completely restored.  The CPU may
	 * change underneath us, but the only part of our context that
	 * lives in the CPU is CR0.TS and that will be "restored" by
	 * setting it on the new CPU.
	 */
	critical_enter();

	KASSERT((curpcb->pcb_flags & PCB_FPUNOSAVE) == 0,
	    ("fpudna while in fpu_kern_enter(FPU_KERN_NOCTX)"));
	if (PCPU_GET(fpcurthread) == curthread) {
		printf("fpudna: fpcurthread == curthread\n");
		stop_emulating();
		critical_exit();
		return;
	}
	if (PCPU_GET(fpcurthread) != NULL) {
		panic("fpudna: fpcurthread = %p (%d), curthread = %p (%d)\n",
		    PCPU_GET(fpcurthread), PCPU_GET(fpcurthread)->td_tid,
		    curthread, curthread->td_tid);
	}
	stop_emulating();
	/*
	 * Record new context early in case frstor causes a trap.
	 */
	PCPU_SET(fpcurthread, curthread);

	fpu_clean_state();

	if ((curpcb->pcb_flags & PCB_FPUINITDONE) == 0) {
		/*
		 * This is the first time this thread has used the FPU or
		 * the PCB doesn't contain a clean FPU state.  Explicitly
		 * load an initial state.
		 *
		 * We prefer to restore the state from the actual save
		 * area in PCB instead of directly loading from
		 * fpu_initialstate, to ignite the XSAVEOPT
		 * tracking engine.
		 */
		bcopy(fpu_initialstate, curpcb->pcb_save,
		    cpu_max_ext_state_size);
		fpurestore(curpcb->pcb_save);
		if (curpcb->pcb_initial_fpucw != __INITIAL_FPUCW__)
			fldcw(curpcb->pcb_initial_fpucw);
		if (PCB_USER_FPU(curpcb))
			set_pcb_flags(curpcb,
			    PCB_FPUINITDONE | PCB_USERFPUINITDONE);
		else
			set_pcb_flags(curpcb, PCB_FPUINITDONE);
	} else
		fpurestore(curpcb->pcb_save);
	critical_exit();
}

void
fpudrop(void)
{
	struct thread *td;

	td = PCPU_GET(fpcurthread);
	KASSERT(td == curthread, ("fpudrop: fpcurthread != curthread"));
	CRITICAL_ASSERT(td);
	PCPU_SET(fpcurthread, NULL);
	clear_pcb_flags(td->td_pcb, PCB_FPUINITDONE);
	start_emulating();
}

/*
 * Get the user state of the FPU into pcb->pcb_user_save without
 * dropping ownership (if possible).  It returns the FPU ownership
 * status.
 */
int
fpugetregs(struct thread *td)
{
	struct pcb *pcb;
	uint64_t *xstate_bv, bit;
	char *sa;
	int max_ext_n, i, owned;

	pcb = td->td_pcb;
	if ((pcb->pcb_flags & PCB_USERFPUINITDONE) == 0) {
		bcopy(fpu_initialstate, get_pcb_user_save_pcb(pcb),
		    cpu_max_ext_state_size);
		get_pcb_user_save_pcb(pcb)->sv_env.en_cw =
		    pcb->pcb_initial_fpucw;
		fpuuserinited(td);
		return (_MC_FPOWNED_PCB);
	}
	critical_enter();
	if (td == PCPU_GET(fpcurthread) && PCB_USER_FPU(pcb)) {
		fpusave(get_pcb_user_save_pcb(pcb));
		owned = _MC_FPOWNED_FPU;
	} else {
		owned = _MC_FPOWNED_PCB;
	}
	critical_exit();
	if (use_xsave) {
		/*
		 * Handle partially saved state.
		 */
		sa = (char *)get_pcb_user_save_pcb(pcb);
		xstate_bv = (uint64_t *)(sa + sizeof(struct savefpu) +
		    offsetof(struct xstate_hdr, xstate_bv));
		max_ext_n = flsl(xsave_mask);
		for (i = 0; i < max_ext_n; i++) {
			bit = 1ULL << i;
			if ((xsave_mask & bit) == 0 || (*xstate_bv & bit) != 0)
				continue;
			bcopy((char *)fpu_initialstate +
			    xsave_area_desc[i].offset,
			    sa + xsave_area_desc[i].offset,
			    xsave_area_desc[i].size);
			*xstate_bv |= bit;
		}
	}
	return (owned);
}

void
fpuuserinited(struct thread *td)
{
	struct pcb *pcb;

	pcb = td->td_pcb;
	if (PCB_USER_FPU(pcb))
		set_pcb_flags(pcb,
		    PCB_FPUINITDONE | PCB_USERFPUINITDONE);
	else
		set_pcb_flags(pcb, PCB_FPUINITDONE);
}

int
fpusetxstate(struct thread *td, char *xfpustate, size_t xfpustate_size)
{
	struct xstate_hdr *hdr, *ehdr;
	size_t len, max_len;
	uint64_t bv;

	/* XXXKIB should we clear all extended state in xstate_bv instead ? */
	if (xfpustate == NULL)
		return (0);
	if (!use_xsave)
		return (EOPNOTSUPP);

	len = xfpustate_size;
	if (len < sizeof(struct xstate_hdr))
		return (EINVAL);
	max_len = cpu_max_ext_state_size - sizeof(struct savefpu);
	if (len > max_len)
		return (EINVAL);

	ehdr = (struct xstate_hdr *)xfpustate;
	bv = ehdr->xstate_bv;

	/*
	 * Avoid #gp.
	 */
	if (bv & ~xsave_mask)
		return (EINVAL);

	hdr = (struct xstate_hdr *)(get_pcb_user_save_td(td) + 1);

	hdr->xstate_bv = bv;
	bcopy(xfpustate + sizeof(struct xstate_hdr),
	    (char *)(hdr + 1), len - sizeof(struct xstate_hdr));

	return (0);
}

/*
 * Set the state of the FPU.
 */
int
fpusetregs(struct thread *td, struct savefpu *addr, char *xfpustate,
    size_t xfpustate_size)
{
	struct pcb *pcb;
	int error;

	addr->sv_env.en_mxcsr &= cpu_mxcsr_mask;
	pcb = td->td_pcb;
	critical_enter();
	if (td == PCPU_GET(fpcurthread) && PCB_USER_FPU(pcb)) {
		error = fpusetxstate(td, xfpustate, xfpustate_size);
		if (error != 0) {
			critical_exit();
			return (error);
		}
		bcopy(addr, get_pcb_user_save_td(td), sizeof(*addr));
		fpurestore(get_pcb_user_save_td(td));
		critical_exit();
		set_pcb_flags(pcb, PCB_FPUINITDONE | PCB_USERFPUINITDONE);
	} else {
		critical_exit();
		error = fpusetxstate(td, xfpustate, xfpustate_size);
		if (error != 0)
			return (error);
		bcopy(addr, get_pcb_user_save_td(td), sizeof(*addr));
		fpuuserinited(td);
	}
	return (0);
}

/*
 * On AuthenticAMD processors, the fxrstor instruction does not restore
 * the x87's stored last instruction pointer, last data pointer, and last
 * opcode values, except in the rare case in which the exception summary
 * (ES) bit in the x87 status word is set to 1.
 *
 * In order to avoid leaking this information across processes, we clean
 * these values by performing a dummy load before executing fxrstor().
 */
static void
fpu_clean_state(void)
{
	static float dummy_variable = 0.0;
	u_short status;

	/*
	 * Clear the ES bit in the x87 status word if it is currently
	 * set, in order to avoid causing a fault in the upcoming load.
	 */
	fnstsw(&status);
	if (status & 0x80)
		fnclex();

	/*
	 * Load the dummy variable into the x87 stack.  This mangles
	 * the x87 stack, but we don't care since we're about to call
	 * fxrstor() anyway.
	 */
	__asm __volatile("ffree %%st(7); flds %0" : : "m" (dummy_variable));
}

/*
 * This really sucks.  We want the acpi version only, but it requires
 * the isa_if.h file in order to get the definitions.
 */
#include "opt_isa.h"
#ifdef DEV_ISA
#include <isa/isavar.h>
/*
 * This sucks up the legacy ISA support assignments from PNPBIOS/ACPI.
 */
static struct isa_pnp_id fpupnp_ids[] = {
	{ 0x040cd041, "Legacy ISA coprocessor support" }, /* PNP0C04 */
	{ 0 }
};

static int
fpupnp_probe(device_t dev)
{
	int result;

	result = ISA_PNP_PROBE(device_get_parent(dev), dev, fpupnp_ids);
	if (result <= 0)
		device_quiet(dev);
	return (result);
}

static int
fpupnp_attach(device_t dev)
{

	return (0);
}

static device_method_t fpupnp_methods[] = {
	/* Device interface */
	DEVMETHOD(device_probe,		fpupnp_probe),
	DEVMETHOD(device_attach,	fpupnp_attach),
	DEVMETHOD(device_detach,	bus_generic_detach),
	DEVMETHOD(device_shutdown,	bus_generic_shutdown),
	DEVMETHOD(device_suspend,	bus_generic_suspend),
	DEVMETHOD(device_resume,	bus_generic_resume),
	
	{ 0, 0 }
};

static driver_t fpupnp_driver = {
	"fpupnp",
	fpupnp_methods,
	1,			/* no softc */
};

static devclass_t fpupnp_devclass;

DRIVER_MODULE(fpupnp, acpi, fpupnp_driver, fpupnp_devclass, 0, 0);
#endif	/* DEV_ISA */

static MALLOC_DEFINE(M_FPUKERN_CTX, "fpukern_ctx",
    "Kernel contexts for FPU state");

#define	FPU_KERN_CTX_FPUINITDONE 0x01
#define	FPU_KERN_CTX_DUMMY	 0x02	/* avoided save for the kern thread */
#define	FPU_KERN_CTX_INUSE	 0x04

struct fpu_kern_ctx {
	struct savefpu *prev;
	uint32_t flags;
	char hwstate1[];
};

struct fpu_kern_ctx *
fpu_kern_alloc_ctx(u_int flags)
{
	struct fpu_kern_ctx *res;
	size_t sz;

	sz = sizeof(struct fpu_kern_ctx) + XSAVE_AREA_ALIGN +
	    cpu_max_ext_state_size;
	res = malloc(sz, M_FPUKERN_CTX, ((flags & FPU_KERN_NOWAIT) ?
	    M_NOWAIT : M_WAITOK) | M_ZERO);
	return (res);
}

void
fpu_kern_free_ctx(struct fpu_kern_ctx *ctx)
{

	KASSERT((ctx->flags & FPU_KERN_CTX_INUSE) == 0, ("free'ing inuse ctx"));
	/* XXXKIB clear the memory ? */
	free(ctx, M_FPUKERN_CTX);
}

static struct savefpu *
fpu_kern_ctx_savefpu(struct fpu_kern_ctx *ctx)
{
	vm_offset_t p;

	p = (vm_offset_t)&ctx->hwstate1;
	p = roundup2(p, XSAVE_AREA_ALIGN);
	return ((struct savefpu *)p);
}

int
fpu_kern_enter(struct thread *td, struct fpu_kern_ctx *ctx, u_int flags)
{
	struct pcb *pcb;

	pcb = td->td_pcb;
	KASSERT((flags & FPU_KERN_NOCTX) != 0 || ctx != NULL,
	    ("ctx is required when !FPU_KERN_NOCTX"));
	KASSERT(ctx == NULL || (ctx->flags & FPU_KERN_CTX_INUSE) == 0,
	    ("using inuse ctx"));
	KASSERT((pcb->pcb_flags & PCB_FPUNOSAVE) == 0,
	    ("recursive fpu_kern_enter while in PCB_FPUNOSAVE state"));

	if ((flags & FPU_KERN_NOCTX) != 0) {
		critical_enter();
		stop_emulating();
		if (curthread == PCPU_GET(fpcurthread)) {
			fpusave(curpcb->pcb_save);
			PCPU_SET(fpcurthread, NULL);
		} else {
			KASSERT(PCPU_GET(fpcurthread) == NULL,
			    ("invalid fpcurthread"));
		}

		/*
		 * This breaks XSAVEOPT tracker, but
		 * PCB_FPUNOSAVE state is supposed to never need to
		 * save FPU context at all.
		 */
		fpurestore(fpu_initialstate);
		set_pcb_flags(pcb, PCB_KERNFPU | PCB_FPUNOSAVE |
		    PCB_FPUINITDONE);
		return (0);
	}
	if ((flags & FPU_KERN_KTHR) != 0 && is_fpu_kern_thread(0)) {
		ctx->flags = FPU_KERN_CTX_DUMMY | FPU_KERN_CTX_INUSE;
		return (0);
	}
	KASSERT(!PCB_USER_FPU(pcb) || pcb->pcb_save ==
	    get_pcb_user_save_pcb(pcb), ("mangled pcb_save"));
	ctx->flags = FPU_KERN_CTX_INUSE;
	if ((pcb->pcb_flags & PCB_FPUINITDONE) != 0)
		ctx->flags |= FPU_KERN_CTX_FPUINITDONE;
	fpuexit(td);
	ctx->prev = pcb->pcb_save;
	pcb->pcb_save = fpu_kern_ctx_savefpu(ctx);
	set_pcb_flags(pcb, PCB_KERNFPU);
	clear_pcb_flags(pcb, PCB_FPUINITDONE);
	return (0);
}

int
fpu_kern_leave(struct thread *td, struct fpu_kern_ctx *ctx)
{
	struct pcb *pcb;

	pcb = td->td_pcb;

	if ((pcb->pcb_flags & PCB_FPUNOSAVE) != 0) {
		KASSERT(ctx == NULL, ("non-null ctx after FPU_KERN_NOCTX"));
		KASSERT(PCPU_GET(fpcurthread) == NULL,
		    ("non-NULL fpcurthread for PCB_FPUNOSAVE"));
		CRITICAL_ASSERT(td);

		clear_pcb_flags(pcb,  PCB_FPUNOSAVE | PCB_FPUINITDONE);
		start_emulating();
		critical_exit();
	} else {
		KASSERT((ctx->flags & FPU_KERN_CTX_INUSE) != 0,
		    ("leaving not inuse ctx"));
		ctx->flags &= ~FPU_KERN_CTX_INUSE;

		if (is_fpu_kern_thread(0) &&
		    (ctx->flags & FPU_KERN_CTX_DUMMY) != 0)
			return (0);
		KASSERT((ctx->flags & FPU_KERN_CTX_DUMMY) == 0,
		    ("dummy ctx"));
		critical_enter();
		if (curthread == PCPU_GET(fpcurthread))
			fpudrop();
		critical_exit();
		pcb->pcb_save = ctx->prev;
	}

	if (pcb->pcb_save == get_pcb_user_save_pcb(pcb)) {
		if ((pcb->pcb_flags & PCB_USERFPUINITDONE) != 0) {
			set_pcb_flags(pcb, PCB_FPUINITDONE);
			clear_pcb_flags(pcb, PCB_KERNFPU);
		} else
			clear_pcb_flags(pcb, PCB_FPUINITDONE | PCB_KERNFPU);
	} else {
		if ((ctx->flags & FPU_KERN_CTX_FPUINITDONE) != 0)
			set_pcb_flags(pcb, PCB_FPUINITDONE);
		else
			clear_pcb_flags(pcb, PCB_FPUINITDONE);
		KASSERT(!PCB_USER_FPU(pcb), ("unpaired fpu_kern_leave"));
	}
	return (0);
}

int
fpu_kern_thread(u_int flags)
{

	KASSERT((curthread->td_pflags & TDP_KTHREAD) != 0,
	    ("Only kthread may use fpu_kern_thread"));
	KASSERT(curpcb->pcb_save == get_pcb_user_save_pcb(curpcb),
	    ("mangled pcb_save"));
	KASSERT(PCB_USER_FPU(curpcb), ("recursive call"));

	set_pcb_flags(curpcb, PCB_KERNFPU);
	return (0);
}

int
is_fpu_kern_thread(u_int flags)
{

	if ((curthread->td_pflags & TDP_KTHREAD) == 0)
		return (0);
	return ((curpcb->pcb_flags & PCB_KERNFPU) != 0);
}

/*
 * FPU save area alloc/free/init utility routines
 */
struct savefpu *
fpu_save_area_alloc(void)
{

	return (uma_zalloc(fpu_save_area_zone, 0));
}

void
fpu_save_area_free(struct savefpu *fsa)
{

	uma_zfree(fpu_save_area_zone, fsa);
}

void
fpu_save_area_reset(struct savefpu *fsa)
{

	bcopy(fpu_initialstate, fsa, cpu_max_ext_state_size);
}
OpenPOWER on IntegriCloud