Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  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
/* $NetBSD: asm.h,v 1.45 2023/02/23 14:55:10 riastradh Exp $ */

/*
 * Copyright (c) 1991,1990,1989,1994,1995,1996 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */

/*
 *	Assembly coding style
 *
 *	This file contains macros and register defines to
 *	aid in writing more readable assembly code.
 *	Some rules to make assembly code understandable by
 *	a debugger are also noted.
 *
 *	The document
 *
 *		"ALPHA Calling Standard", DEC 27-Apr-90
 *
 *	defines (a superset of) the rules and conventions
 *	we use.  While we make no promise of adhering to
 *	such standard and its evolution (esp where we
 *	can get faster code paths) it is certainly intended
 *	that we be interoperable with such standard.
 *
 *	In this sense, this file is a proper part of the
 *	definition of the (software) Alpha architecture.
 */

/*
 *	Symbolic register names and register saving rules
 *
 *	Legend:
 *		T	Saved by caller (Temporaries)
 *		S	Saved by callee (call-Safe registers)
 */

#define	v0	$0	/* (T)		return value		*/
#define t0	$1	/* (T)		temporary registers	*/
#define t1	$2
#define t2	$3
#define t3	$4
#define t4	$5
#define t5	$6
#define t6	$7
#define t7	$8

#define s0	$9	/* (S)		call-safe registers	*/
#define s1	$10
#define s2	$11
#define s3	$12
#define s4	$13
#define s5	$14
#define s6	$15
#define a0	$16	/* (T)		argument registers	*/
#define a1	$17
#define a2	$18
#define a3	$19
#define a4	$20
#define a5	$21
#define t8	$22	/* (T)		temporary registers	*/
#define t9	$23
#define t10	$24
#define t11	$25
#define ra	$26	/* (S)		return address		*/
#define t12	$27	/* (T)		another temporary	*/
#define at_reg	$28	/* (T)		assembler scratch	*/
#define	gp	$29	/* (T)		(local) data pointer	*/
#define sp	$30	/* (S)		stack pointer		*/
#define zero	$31	/* 		wired zero		*/

/* Floating point registers  (XXXX VERIFY THIS) */
#define	fv0	$f0	/* (T)		return value (real)	*/
#define	fv1	$f1	/* (T)		return value (imaginary)*/
#define	ft0	fv1
#define	fs0	$f2	/* (S)		call-safe registers	*/
#define	fs1	$f3
#define	fs2	$f4
#define	fs3	$f5
#define	fs4	$f6
#define	fs5	$f7
#define	fs6	$f8
#define	fs7	$f9
#define	ft1	$f10	/* (T)		temporary registers	*/
#define	ft2	$f11
#define	ft3	$f12
#define	ft4	$f13
#define	ft5	$f14
#define	ft6	$f15
#define	fa0	$f16	/* (T)		argument registers	*/
#define	fa1	$f17
#define	fa2	$f18
#define	fa3	$f19
#define	fa4	$f20
#define	fa5	$f21
#define	ft7	$f22	/* (T)		more temporaries	*/
#define	ft8	$f23
#define	ft9	$f24
#define	ft10	$f25
#define	ft11	$f26
#define	ft12	$f27
#define	ft13	$f28
#define	ft14	$f29
#define	ft15	$f30
#define	fzero	$f31	/*		wired zero		*/


/* Other DEC standard names */
#define ai	$25	/* (T)		argument information	*/
#define pv	$27	/* (T)		procedure value		*/


/*
 * Useful stuff.
 */
#ifdef __STDC__
#define	__CONCAT(a,b)	a ## b
#else
#define	__CONCAT(a,b)	a/**/b
#endif
#define ___CONCAT(a,b)	__CONCAT(a,b)

/*
 * Macro to make a local label name.
 */
#define	LLABEL(name,num)	___CONCAT(___CONCAT(L,name),num)

/*
 *
 * Debuggers need symbol table information to be able to properly
 * decode a stack trace.  The minimum that should be provided is:
 *
 * 	name:
 *		.proc	name,numargs
 *
 * where "name" 	is the function's name;
 *	 "numargs"	how many arguments it expects. For varargs
 *			procedures this should be a negative number,
 *			indicating the minimum required number of
 *			arguments (which is at least 1);
 *
 * NESTED functions (functions that call other functions) should define
 * how they handle their stack frame in a .frame directive:
 *
 *		.frame	framesize, pc_reg, i_mask, f_mask
 *
 * where "framesize"	is the size of the frame for this function, in bytes.
 *			That is:
 *				new_sp + framesize == old_sp
 *			Framesizes should be rounded to a cacheline size.
 *			Note that old_sp plays the role of a conventional
 *			"frame pointer";
 *	 "pc_reg"	is either a register which preserves the caller's PC
 *			or 'std', if std the saved PC should be stored at
 *				old_sp-8
 * 	 "i_mask"	is a bitmask that indicates which of the integer
 *			registers are saved. See the M_xx defines at the
 *			end for the encoding of this 32bit value.
 *	 "f_mask"	is the same, for floating point registers.
 *
 * Note, 10/31/97: This is interesting but it isn't the way gcc outputs
 * frame directives and it isn't the way the macros below output them
 * either. Frame directives look like this:
 *
 *		.frame	$15,framesize,$26,0
 *
 * If no fp is set up then $30 should be used instead of $15.
 * Also, gdb expects to find a <lda sp,-framesize(sp)> at the beginning
 * of a procedure. Don't use things like sub sp,framesize,sp for this
 * reason. End Note 10/31/97. ross@NetBSD.org
 *
 * Note that registers should be saved starting at "old_sp-8", where the
 * return address should be stored. Other registers follow at -16-24-32..
 * starting from register 0 (if saved) and up. Then float registers (ifany)
 * are saved.
 *
 * If you need to alias a leaf function, or to provide multiple entry points
 * use the LEAF() macro for the main entry point and XLEAF() for the other
 * additional/alternate entry points.
 * "XLEAF"s must be nested within a "LEAF" and a ".end".
 * Similar rules for nested routines, e.g. use NESTED/XNESTED
 * Symbols that should not be exported can be declared with the STATIC_xxx
 * macros.
 *
 * All functions must be terminated by the END macro
 *
 * It is conceivable, although currently at the limits of compiler
 * technology, that while performing inter-procedural optimizations
 * the compiler/linker be able to avoid unnecessary register spills
 * if told about the register usage of LEAF procedures (and by transitive
 * closure of NESTED procedures as well).  Assembly code can help
 * this process using the .reguse directive:
 *
 *		.reguse	i_mask, f_mask
 *
 * where the register masks are built as above or-ing M_xx defines.
 *	
 *
 * All symbols are internal unless EXPORTed.  Symbols that are IMPORTed
 * must be appropriately described to the debugger.
 *
 */

/*
 * MCOUNT
 */

#ifndef GPROF
#define MCOUNT	/* nothing */
#else
#define MCOUNT							\
	.set noat;						\
	jsr	at_reg,_mcount;					\
	.set at
#endif
/*
 * PALVECT, ESETUP, and ERSAVE
 *	Declare a palcode transfer point, and carefully construct
 *	gdb symbols with an unusual _negative_ register-save offset
 *	so that gdb can find the otherwise lost PC and then
 *	invert the vector for traceback. Also, fix up framesize,
 *	allowing for the palframe for the same reason.
 */

#define PALVECT(_name_)						\
	ESETUP(_name_);						\
	ERSAVE()

#define	ESETUP(_name_)						\
	/* .loc	1 __LINE__; */					\
	.globl	_name_;						\
	.ent	_name_ 0;					\
_name_:;							\
	.set	noat;						\
	lda	sp,-(FRAME_SW_SIZE*8)(sp);			\
	.frame	$30,(FRAME_SW_SIZE+6)*8,$26,0;   /* give gdb the real size */\
	.mask	0x4000000,-0x28;				\
	.set	at

#define	ERSAVE()						\
	.set	noat;						\
	stq	at_reg,(FRAME_AT*8)(sp);			\
	.set	at;						\
	stq	ra,(FRAME_RA*8)(sp);				\
	/* .loc	1 __LINE__; */					\
	bsr	ra,exception_save_regs         /* jmp/CALL trashes pv/t12 */


/*
 * LEAF
 *	Declare a global leaf function.
 *	A leaf function does not call other functions AND does not
 *	use any register that is callee-saved AND does not modify
 *	the stack pointer.
 */
#define	LEAF(_name_,_n_args_)					\
	.globl	_name_;						\
	.ent	_name_ 0;					\
_name_:;							\
	.frame	sp,0,ra;					\
	MCOUNT
/* should have been
	.proc	_name_,_n_args_;				\
	.frame	0,ra,0,0
*/

#define	LEAF_NOPROFILE(_name_,_n_args_)					\
	.globl	_name_;						\
	.ent	_name_ 0;					\
_name_:;							\
	.frame	sp,0,ra
/* should have been
	.proc	_name_,_n_args_;				\
	.frame	0,ra,0,0
*/

/*
 * STATIC_LEAF
 *	Declare a local leaf function.
 */
#define STATIC_LEAF(_name_,_n_args_)				\
	.ent	_name_ 0;					\
_name_:;							\
	.frame	sp,0,ra;					\
	MCOUNT
/* should have been
	.proc	_name_,_n_args_;				\
	.frame	0,ra,0,0
*/
/*
 * XLEAF
 *	Global alias for a leaf function, or alternate entry point
 */
#define	XLEAF(_name_,_n_args_)					\
	.globl	_name_;						\
	.aent	_name_ 0;					\
_name_:
/* should have been
	.aproc	_name_,_n_args_;
*/

/*
 * STATIC_XLEAF
 *	Local alias for a leaf function, or alternate entry point
 */
#define	STATIC_XLEAF(_name_,_n_args_)				\
	.aent	_name_ 0;					\
_name_:
/* should have been
	.aproc	_name_,_n_args_;
*/

/*
 * NESTED
 *	Declare a (global) nested function
 *	A nested function calls other functions and needs
 *	therefore stack space to save/restore registers.
 */
#define	NESTED(_name_, _n_args_, _framesize_, _pc_reg_, _i_mask_, _f_mask_ ) \
	.globl	_name_;						\
	.ent	_name_ 0;					\
_name_:;							\
	.frame	sp,_framesize_,_pc_reg_;			\
	.livereg _i_mask_,_f_mask_;				\
	MCOUNT
/* should have been
	.proc	_name_,_n_args_;				\
	.frame	_framesize_, _pc_reg_, _i_mask_, _f_mask_
*/

#define	NESTED_NOPROFILE(_name_, _n_args_, _framesize_, _pc_reg_, _i_mask_, _f_mask_ ) \
	.globl	_name_;						\
	.ent	_name_ 0;					\
_name_:;							\
	.frame	sp,_framesize_,_pc_reg_;			\
	.livereg _i_mask_,_f_mask_
/* should have been
	.proc	_name_,_n_args_;				\
	.frame	_framesize_, _pc_reg_, _i_mask_, _f_mask_
*/

/*
 * STATIC_NESTED
 *	Declare a local nested function.
 */
#define	STATIC_NESTED(_name_, _n_args_, _framesize_, _pc_reg_, _i_mask_, _f_mask_ ) \
	.ent	_name_ 0;					\
_name_:;							\
	.frame	sp,_framesize_,_pc_reg_;			\
	.livereg _i_mask_,_f_mask_;				\
	MCOUNT
/* should have been
	.proc	_name_,_n_args_;				\
	.frame	_framesize_, _pc_reg_, _i_mask_, _f_mask_
*/

/*
 * XNESTED
 *	Same as XLEAF, for a nested function.
 */
#define	XNESTED(_name_,_n_args_)				\
	.globl	_name_;						\
	.aent	_name_ 0;					\
_name_:
/* should have been
	.aproc	_name_,_n_args_;
*/


/*
 * STATIC_XNESTED
 *	Same as STATIC_XLEAF, for a nested function.
 */
#define	STATIC_XNESTED(_name_,_n_args_)				\
	.aent	_name_ 0;					\
_name_:
/* should have been
	.aproc	_name_,_n_args_;
*/


/*
 * END
 *	Function delimiter
 */
#define	END(_name_)						\
	.end	_name_


/*
 * CALL
 *	Function invocation
 */
#define	CALL(_name_)						\
	/* .loc	1 __LINE__; */					\
	jsr	ra,_name_;					\
	ldgp	gp,0(ra)
/* but this would cover longer jumps
	br	ra,.+4;						\
	bsr	ra,_name_
*/


/*
 * RET
 *	Return from function
 */
#define	RET							\
	ret	zero,(ra),1


/*
 * EXPORT
 *	Export a symbol
 */
#define	EXPORT(_name_)						\
	.globl	_name_;						\
_name_:


/*
 * IMPORT
 *	Make an external name visible, typecheck the size
 */
#define	IMPORT(_name_, _size_)					\
	.extern	_name_,_size_


/*
 * ABS
 *	Define an absolute symbol
 */
#define	ABS(_name_, _value_)					\
	.globl	_name_;						\
_name_	=	_value_


/*
 * BSS
 *	Allocate un-initialized space for a global symbol
 */
#define	BSS(_name_,_numbytes_)					\
	.comm	_name_,_numbytes_

/*
 * VECTOR
 *	Make an exception entry point look like a called function,
 *	to make it digestible to the debugger (KERNEL only)
 */
#define	VECTOR(_name_, _i_mask_)				\
	.globl	_name_;						\
	.ent	_name_ 0;					\
_name_:;							\
	.mask	_i_mask_|IM_EXC,0;				\
	.frame	sp,MSS_SIZE,ra;				
/*	.livereg _i_mask_|IM_EXC,0	*/
/* should have been
	.proc	_name_,1;					\
	.frame	MSS_SIZE,$31,_i_mask_,0;			\
*/

/*
 * MSG
 *	Allocate space for a message (a read-only ascii string)
 */
#define	ASCIZ	.asciz
#define	MSG(msg,reg,label)					\
	lda reg, label;						\
	.data;							\
label:	ASCIZ msg;						\
	.text;

/*
 * PRINTF
 *	Print a message
 */
#define	PRINTF(msg,label)					\
	MSG(msg,a0,label);					\
	CALL(printf)

/*
 * PANIC
 *	Fatal error (KERNEL)
 */
#define	PANIC(msg,label)					\
	MSG(msg,a0,label);					\
	CALL(panic)

/*
 * Register mask defines, used to define both save
 * and use register sets.
 *
 * NOTE: The bit order should HAVE BEEN maintained when saving
 *	 registers on the stack: sp goes at the highest
 *	 address, gp lower on the stack, etc etc
 *	 BUT NOONE CARES ABOUT DEBUGGERS AT MIPS
 */

#define	IM_EXC	0x80000000
#define	IM_SP	0x40000000
#define	IM_GP	0x20000000
#define	IM_AT	0x10000000
#define	IM_T12	0x08000000
#	define	IM_PV	IM_T4
#define	IM_RA	0x04000000
#define	IM_T11	0x02000000
#	define	IM_AI	IM_T3
#define	IM_T10	0x01000000
#define	IM_T9	0x00800000
#define	IM_T8	0x00400000
#define	IM_A5	0x00200000
#define	IM_A4	0x00100000
#define	IM_A3	0x00080000
#define	IM_A2	0x00040000
#define	IM_A1	0x00020000
#define	IM_A0	0x00010000
#define	IM_S6	0x00008000
#define	IM_S5	0x00004000
#define	IM_S4	0x00002000
#define	IM_S3	0x00001000
#define	IM_S2	0x00000800
#define	IM_S1	0x00000400
#define	IM_S0	0x00000200
#define	IM_T7	0x00000100
#define	IM_T6	0x00000080
#define	IM_T5	0x00000040
#define	IM_T4	0x00000020
#define	IM_T3	0x00000010
#define	IM_T2	0x00000008
#define	IM_T1	0x00000004
#define	IM_T0	0x00000002
#define	IM_V0	0x00000001

#define	FM_T15	0x40000000
#define	FM_T14	0x20000000
#define	FM_T13	0x10000000
#define	FM_T12	0x08000000
#define	FM_T11	0x04000000
#define	FM_T10	0x02000000
#define	FM_T9	0x01000000
#define	FM_T8	0x00800000
#define	FM_T7	0x00400000
#define	FM_A5	0x00200000
#define	FM_A4	0x00100000
#define	FM_A3	0x00080000
#define	FM_A2	0x00040000
#define	FM_A1	0x00020000
#define	FM_A0	0x00010000
#define	FM_T6	0x00008000
#define	FM_T5	0x00004000
#define	FM_T4	0x00002000
#define	FM_T3	0x00001000
#define	FM_T2	0x00000800
#define	FM_T1	0x00000400
#define	FM_S7	0x00000200
#define	FM_S6	0x00000100
#define	FM_S5	0x00000080
#define	FM_S4	0x00000040
#define	FM_S3	0x00000020
#define	FM_S2	0x00000010
#define	FM_S1	0x00000008
#define	FM_S0	0x00000004
#define	FM_T0	0x00000002
#define	FM_V1	FM_T0
#define	FM_V0	0x00000001

/* Pull in PAL "function" codes. */
#include <machine/pal.h>

/*
 * System call glue.
 */
#define	SYSCALLNUM(name)					\
	___CONCAT(SYS_,name)

#define	CALLSYS_NOERROR(name)					\
	ldiq	v0, SYSCALLNUM(name);				\
	call_pal PAL_OSF1_callsys

#define LINUX_SYSCALLNUM(name)					\
	___CONCAT(LINUX_SYS_,name)

#define LINUX_CALLSYS_NOERROR(name)				\
	ldiq	v0, LINUX_SYSCALLNUM(name);			\
	call_pal PAL_OSF1_callsys

/*
 * Load the global pointer.
 */
#define	LDGP(reg)						\
	ldgp	gp, 0(reg)

/*
 * WEAK_ALIAS: create a weak alias.
 */
#define WEAK_ALIAS(alias,sym)					\
	.weak alias;						\
	alias = sym

/*
 * STRONG_ALIAS: create a strong alias.
 */
#define STRONG_ALIAS(alias,sym)					\
	.globl alias;						\
	alias = sym

/*
 * WARN_REFERENCES: create a warning if the specified symbol is referenced.
 */
#ifdef __STDC__
#define	WARN_REFERENCES(sym,msg)					\
	.pushsection .gnu.warning. ## sym;				\
	.ascii msg;							\
	.popsection
#else
#define	WARN_REFERENCES(sym,msg)					\
	.pushsection .gnu.warning./**/sym;				\
	.ascii msg;							\
	.popsection
#endif /* __STDC__ */

/*
 * Kernel RCS ID tag and copyright macros
 */
#define	__SECTIONSTRING(_sec, _str)				\
	.pushsection _sec,"MS",@progbits,1;			\
	.asciz _str;						\
	.popsection

#ifdef _KERNEL

#define	__KERNEL_RCSID(_n, _s)		__SECTIONSTRING(.ident, _s)
#define	__KERNEL_COPYRIGHT(_n, _s)	__SECTIONSTRING(.copyright, _s)

#ifdef NO_KERNEL_RCSIDS
#undef __KERNEL_RCSID
#define	__KERNEL_RCSID(_n, _s)		/* nothing */
#endif

#if defined(MULTIPROCESSOR)

/*
 * Get various per-cpu values.  A pointer to our cpu_info structure
 * is stored in SysValue.  These macros clobber v0, t0, t8..t11.
 * SET_CURLWP also clobbers a0.
 *
 * All return values are in v0.
 */
#define	GET_CURLWP							\
	call_pal PAL_OSF1_rdval

/*
 * Issue barriers to coordinate mutex_exit on this CPU with
 * mutex_vector_enter on another CPU.
 *
 * 1. Any prior mutex_exit by oldlwp must be visible to other
 *    CPUs before we set ci_curlwp := newlwp on this one,
 *    requiring a store-before-store barrier.
 *
 * 2. ci_curlwp := newlwp must be visible on all other CPUs
 *    before any subsequent mutex_exit by newlwp can even test
 *    whether there might be waiters, requiring a
 *    store-before-load barrier.
 *
 * See kern_mutex.c for details -- this is necessary for
 * adaptive mutexes to detect whether the lwp is on the CPU in
 * order to safely block without requiring atomic r/m/w in
 * mutex_exit.
 */
#define	SET_CURLWP(r)							\
	ldq	v0, L_CPU(r)					;	\
	mov	r, a0						;	\
	wmb	/* store-before-store XXX patch out if !MP? */	;	\
	stq	r, CPU_INFO_CURLWP(v0)				;	\
	mb	/* store-before-load XXX patch out if !MP? */	;	\
	call_pal PAL_OSF1_wrval

#else	/* if not MULTIPROCESSOR... */

IMPORT(cpu_info_primary, CPU_INFO_SIZEOF)

#define	GET_CURLWP		lda v0, cpu_info_primary	;	\
				ldq v0, CPU_INFO_CURLWP(v0)

#define	SET_CURLWP(r)		lda v0, cpu_info_primary 	;	\
				stq r, CPU_INFO_CURLWP(v0)

#endif /* MULTIPROCESSOR */
#else
#define	RCSID(_s)		__SECTIONSTRING(.ident, _s)

#endif /* _KERNEL */