1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 *
22 * $FreeBSD$
23 */
24/*
25 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
26 * Use is subject to license terms.
27 */
28#include <sys/cdefs.h>
29
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/kernel.h>
33#include <sys/stack.h>
34#include <sys/pcpu.h>
35
36#include <machine/frame.h>
37#include <machine/md_var.h>
38#include <machine/reg.h>
39#include <machine/stack.h>
40#include <x86/ifunc.h>
41
42#include <vm/vm.h>
43#include <vm/vm_param.h>
44#include <vm/pmap.h>
45
46#include "regset.h"
47
48uint8_t dtrace_fuword8_nocheck(void *);
49uint16_t dtrace_fuword16_nocheck(void *);
50uint32_t dtrace_fuword32_nocheck(void *);
51uint64_t dtrace_fuword64_nocheck(void *);
52
53int	dtrace_ustackdepth_max = 2048;
54
55void
56dtrace_getpcstack(pc_t *pcstack, int pcstack_limit, int aframes,
57    uint32_t *intrpc)
58{
59	struct thread *td;
60	int depth = 0;
61	register_t rbp;
62	struct amd64_frame *frame;
63	vm_offset_t callpc;
64	pc_t caller = (pc_t) solaris_cpu[curcpu].cpu_dtrace_caller;
65
66	if (intrpc != 0)
67		pcstack[depth++] = (pc_t) intrpc;
68
69	aframes++;
70
71	__asm __volatile("movq %%rbp,%0" : "=r" (rbp));
72
73	frame = (struct amd64_frame *)rbp;
74	td = curthread;
75	while (depth < pcstack_limit) {
76		if (!kstack_contains(curthread, (vm_offset_t)frame,
77		    sizeof(*frame)))
78			break;
79
80		callpc = frame->f_retaddr;
81
82		if (!INKERNEL(callpc))
83			break;
84
85		if (aframes > 0) {
86			aframes--;
87			if ((aframes == 0) && (caller != 0)) {
88				pcstack[depth++] = caller;
89			}
90		} else {
91			pcstack[depth++] = callpc;
92		}
93
94		if ((vm_offset_t)frame->f_frame <= (vm_offset_t)frame)
95			break;
96		frame = frame->f_frame;
97	}
98
99	for (; depth < pcstack_limit; depth++) {
100		pcstack[depth] = 0;
101	}
102}
103
104static int
105dtrace_getustack_common(uint64_t *pcstack, int pcstack_limit, uintptr_t pc,
106    uintptr_t sp)
107{
108	uintptr_t oldsp;
109	volatile uint16_t *flags =
110	    (volatile uint16_t *)&cpu_core[curcpu].cpuc_dtrace_flags;
111	int ret = 0;
112
113	ASSERT(pcstack == NULL || pcstack_limit > 0);
114	ASSERT(dtrace_ustackdepth_max > 0);
115
116	while (pc != 0) {
117		/*
118		 * We limit the number of times we can go around this
119		 * loop to account for a circular stack.
120		 */
121		if (ret++ >= dtrace_ustackdepth_max) {
122			*flags |= CPU_DTRACE_BADSTACK;
123			cpu_core[curcpu].cpuc_dtrace_illval = sp;
124			break;
125		}
126
127		if (pcstack != NULL) {
128			*pcstack++ = (uint64_t)pc;
129			pcstack_limit--;
130			if (pcstack_limit <= 0)
131				break;
132		}
133
134		if (sp == 0)
135			break;
136
137		oldsp = sp;
138
139		pc = dtrace_fuword64((void *)(sp +
140			offsetof(struct amd64_frame, f_retaddr)));
141		sp = dtrace_fuword64((void *)sp);
142
143		if (sp == oldsp) {
144			*flags |= CPU_DTRACE_BADSTACK;
145			cpu_core[curcpu].cpuc_dtrace_illval = sp;
146			break;
147		}
148
149		/*
150		 * This is totally bogus:  if we faulted, we're going to clear
151		 * the fault and break.  This is to deal with the apparently
152		 * broken Java stacks on x86.
153		 */
154		if (*flags & CPU_DTRACE_FAULT) {
155			*flags &= ~CPU_DTRACE_FAULT;
156			break;
157		}
158	}
159
160	return (ret);
161}
162
163void
164dtrace_getupcstack(uint64_t *pcstack, int pcstack_limit)
165{
166	proc_t *p = curproc;
167	struct trapframe *tf;
168	uintptr_t pc, sp, fp;
169	volatile uint16_t *flags =
170	    (volatile uint16_t *)&cpu_core[curcpu].cpuc_dtrace_flags;
171	int n;
172
173	if (*flags & CPU_DTRACE_FAULT)
174		return;
175
176	if (pcstack_limit <= 0)
177		return;
178
179	/*
180	 * If there's no user context we still need to zero the stack.
181	 */
182	if (p == NULL || (tf = curthread->td_frame) == NULL)
183		goto zero;
184
185	*pcstack++ = (uint64_t)p->p_pid;
186	pcstack_limit--;
187
188	if (pcstack_limit <= 0)
189		return;
190
191	pc = tf->tf_rip;
192	fp = tf->tf_rbp;
193	sp = tf->tf_rsp;
194
195	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_ENTRY)) {
196		/*
197		 * In an entry probe.  The frame pointer has not yet been
198		 * pushed (that happens in the function prologue).  The
199		 * best approach is to add the current pc as a missing top
200		 * of stack and back the pc up to the caller, which is stored
201		 * at the current stack pointer address since the call
202		 * instruction puts it there right before the branch.
203		 */
204
205		*pcstack++ = (uint64_t)pc;
206		pcstack_limit--;
207		if (pcstack_limit <= 0)
208			return;
209
210		pc = dtrace_fuword64((void *) sp);
211	}
212
213	n = dtrace_getustack_common(pcstack, pcstack_limit, pc, fp);
214	ASSERT(n >= 0);
215	ASSERT(n <= pcstack_limit);
216
217	pcstack += n;
218	pcstack_limit -= n;
219
220zero:
221	while (pcstack_limit-- > 0)
222		*pcstack++ = 0;
223}
224
225int
226dtrace_getustackdepth(void)
227{
228	proc_t *p = curproc;
229	struct trapframe *tf;
230	uintptr_t pc, fp, sp;
231	int n = 0;
232
233	if (p == NULL || (tf = curthread->td_frame) == NULL)
234		return (0);
235
236	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_FAULT))
237		return (-1);
238
239	pc = tf->tf_rip;
240	fp = tf->tf_rbp;
241	sp = tf->tf_rsp;
242
243	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_ENTRY)) {
244		/*
245		 * In an entry probe.  The frame pointer has not yet been
246		 * pushed (that happens in the function prologue).  The
247		 * best approach is to add the current pc as a missing top
248		 * of stack and back the pc up to the caller, which is stored
249		 * at the current stack pointer address since the call
250		 * instruction puts it there right before the branch.
251		 */
252
253		pc = dtrace_fuword64((void *) sp);
254		n++;
255	}
256
257	n += dtrace_getustack_common(NULL, 0, pc, fp);
258
259	return (n);
260}
261
262void
263dtrace_getufpstack(uint64_t *pcstack, uint64_t *fpstack, int pcstack_limit)
264{
265	proc_t *p = curproc;
266	struct trapframe *tf;
267	uintptr_t pc, sp, fp;
268	volatile uint16_t *flags =
269	    (volatile uint16_t *)&cpu_core[curcpu].cpuc_dtrace_flags;
270#ifdef notyet	/* XXX signal stack */
271	uintptr_t oldcontext;
272	size_t s1, s2;
273#endif
274
275	if (*flags & CPU_DTRACE_FAULT)
276		return;
277
278	if (pcstack_limit <= 0)
279		return;
280
281	/*
282	 * If there's no user context we still need to zero the stack.
283	 */
284	if (p == NULL || (tf = curthread->td_frame) == NULL)
285		goto zero;
286
287	*pcstack++ = (uint64_t)p->p_pid;
288	pcstack_limit--;
289
290	if (pcstack_limit <= 0)
291		return;
292
293	pc = tf->tf_rip;
294	sp = tf->tf_rsp;
295	fp = tf->tf_rbp;
296
297#ifdef notyet /* XXX signal stack */
298	oldcontext = lwp->lwp_oldcontext;
299	s1 = sizeof (struct xframe) + 2 * sizeof (long);
300	s2 = s1 + sizeof (siginfo_t);
301#endif
302
303	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_ENTRY)) {
304		*pcstack++ = (uint64_t)pc;
305		*fpstack++ = 0;
306		pcstack_limit--;
307		if (pcstack_limit <= 0)
308			return;
309
310		pc = dtrace_fuword64((void *)sp);
311	}
312
313	while (pc != 0) {
314		*pcstack++ = (uint64_t)pc;
315		*fpstack++ = fp;
316		pcstack_limit--;
317		if (pcstack_limit <= 0)
318			break;
319
320		if (fp == 0)
321			break;
322
323#ifdef notyet /* XXX signal stack */
324		if (oldcontext == sp + s1 || oldcontext == sp + s2) {
325			ucontext_t *ucp = (ucontext_t *)oldcontext;
326			greg_t *gregs = ucp->uc_mcontext.gregs;
327
328			sp = dtrace_fulword(&gregs[REG_FP]);
329			pc = dtrace_fulword(&gregs[REG_PC]);
330
331			oldcontext = dtrace_fulword(&ucp->uc_link);
332		} else
333#endif /* XXX */
334		{
335			pc = dtrace_fuword64((void *)(fp +
336				offsetof(struct amd64_frame, f_retaddr)));
337			fp = dtrace_fuword64((void *)fp);
338		}
339
340		/*
341		 * This is totally bogus:  if we faulted, we're going to clear
342		 * the fault and break.  This is to deal with the apparently
343		 * broken Java stacks on x86.
344		 */
345		if (*flags & CPU_DTRACE_FAULT) {
346			*flags &= ~CPU_DTRACE_FAULT;
347			break;
348		}
349	}
350
351zero:
352	while (pcstack_limit-- > 0)
353		*pcstack++ = 0;
354}
355
356/*ARGSUSED*/
357uint64_t
358dtrace_getarg(int arg, int aframes)
359{
360	uintptr_t val;
361	struct amd64_frame *fp = (struct amd64_frame *)dtrace_getfp();
362	uintptr_t *stack;
363	int i;
364
365	/*
366	 * A total of 6 arguments are passed via registers; any argument with
367	 * index of 5 or lower is therefore in a register.
368	 */
369	int inreg = 5;
370
371	for (i = 1; i <= aframes; i++) {
372		fp = fp->f_frame;
373
374		if (P2ROUNDUP(fp->f_retaddr, 16) ==
375		    (long)dtrace_invop_callsite) {
376			/*
377			 * In the case of amd64, we will use the pointer to the
378			 * regs structure that was pushed when we took the
379			 * trap.  To get this structure, we must increment
380			 * beyond the frame structure, and then again beyond
381			 * the calling RIP stored in dtrace_invop().  If the
382			 * argument that we're seeking is passed on the stack,
383			 * we'll pull the true stack pointer out of the saved
384			 * registers and decrement our argument by the number
385			 * of arguments passed in registers; if the argument
386			 * we're seeking is passed in registers, we can just
387			 * load it directly.
388			 */
389			struct trapframe *tf = (struct trapframe *)&fp[1];
390
391			if (arg <= inreg) {
392				switch (arg) {
393				case 0:
394					stack = (uintptr_t *)&tf->tf_rdi;
395					break;
396				case 1:
397					stack = (uintptr_t *)&tf->tf_rsi;
398					break;
399				case 2:
400					stack = (uintptr_t *)&tf->tf_rdx;
401					break;
402				case 3:
403					stack = (uintptr_t *)&tf->tf_rcx;
404					break;
405				case 4:
406					stack = (uintptr_t *)&tf->tf_r8;
407					break;
408				case 5:
409					stack = (uintptr_t *)&tf->tf_r9;
410					break;
411				}
412				arg = 0;
413			} else {
414				stack = (uintptr_t *)(tf->tf_rsp);
415				arg -= inreg;
416			}
417			goto load;
418		}
419
420	}
421
422	/*
423	 * We know that we did not come through a trap to get into
424	 * dtrace_probe() -- the provider simply called dtrace_probe()
425	 * directly.  As this is the case, we need to shift the argument
426	 * that we're looking for:  the probe ID is the first argument to
427	 * dtrace_probe(), so the argument n will actually be found where
428	 * one would expect to find argument (n + 1).
429	 */
430	arg++;
431
432	if (arg <= inreg) {
433		/*
434		 * This shouldn't happen.  If the argument is passed in a
435		 * register then it should have been, well, passed in a
436		 * register...
437		 */
438		DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
439		return (0);
440	}
441
442	arg -= (inreg + 1);
443	stack = (uintptr_t *)&fp[1];
444
445load:
446	DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
447	val = stack[arg];
448	DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
449
450	return (val);
451}
452
453int
454dtrace_getstackdepth(int aframes)
455{
456	int depth = 0;
457	struct amd64_frame *frame;
458	vm_offset_t rbp;
459
460	aframes++;
461	rbp = dtrace_getfp();
462	frame = (struct amd64_frame *)rbp;
463	depth++;
464	for(;;) {
465		if (!kstack_contains(curthread, (vm_offset_t)frame,
466		    sizeof(*frame)))
467			break;
468		depth++;
469		if (frame->f_frame <= frame)
470			break;
471		frame = frame->f_frame;
472	}
473	if (depth < aframes)
474		return 0;
475	else
476		return depth - aframes;
477}
478
479ulong_t
480dtrace_getreg(struct trapframe *rp, uint_t reg)
481{
482	/* This table is dependent on reg.d. */
483	int regmap[] = {
484		REG_GS,		/* 0  GS */
485		REG_FS,		/* 1  FS */
486		REG_ES,		/* 2  ES */
487		REG_DS,		/* 3  DS */
488		REG_RDI,	/* 4  EDI */
489		REG_RSI,	/* 5  ESI */
490		REG_RBP,	/* 6  EBP, REG_FP */
491		REG_RSP,	/* 7  ESP */
492		REG_RBX,	/* 8  EBX, REG_R1 */
493		REG_RDX,	/* 9  EDX */
494		REG_RCX,	/* 10 ECX */
495		REG_RAX,	/* 11 EAX, REG_R0 */
496		REG_TRAPNO,	/* 12 TRAPNO */
497		REG_ERR,	/* 13 ERR */
498		REG_RIP,	/* 14 EIP, REG_PC */
499		REG_CS,		/* 15 CS */
500		REG_RFL,	/* 16 EFL, REG_PS */
501		REG_RSP,	/* 17 UESP, REG_SP */
502		REG_SS		/* 18 SS */
503	};
504
505#ifdef illumos
506	if (reg <= SS) {
507#else	/* !illumos */
508	if (reg <= GS) {
509#endif
510		if (reg >= sizeof (regmap) / sizeof (int)) {
511			DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
512			return (0);
513		}
514
515		reg = regmap[reg];
516	} else {
517		/* This is dependent on reg.d. */
518#ifdef illumos
519		reg -= SS + 1;
520#else	/* !illumos */
521		reg -= GS + 1;
522#endif
523	}
524
525	switch (reg) {
526	case REG_RDI:
527		return (rp->tf_rdi);
528	case REG_RSI:
529		return (rp->tf_rsi);
530	case REG_RDX:
531		return (rp->tf_rdx);
532	case REG_RCX:
533		return (rp->tf_rcx);
534	case REG_R8:
535		return (rp->tf_r8);
536	case REG_R9:
537		return (rp->tf_r9);
538	case REG_RAX:
539		return (rp->tf_rax);
540	case REG_RBX:
541		return (rp->tf_rbx);
542	case REG_RBP:
543		return (rp->tf_rbp);
544	case REG_R10:
545		return (rp->tf_r10);
546	case REG_R11:
547		return (rp->tf_r11);
548	case REG_R12:
549		return (rp->tf_r12);
550	case REG_R13:
551		return (rp->tf_r13);
552	case REG_R14:
553		return (rp->tf_r14);
554	case REG_R15:
555		return (rp->tf_r15);
556	case REG_DS:
557		return (rp->tf_ds);
558	case REG_ES:
559		return (rp->tf_es);
560	case REG_FS:
561		return (rp->tf_fs);
562	case REG_GS:
563		return (rp->tf_gs);
564	case REG_TRAPNO:
565		return (rp->tf_trapno);
566	case REG_ERR:
567		return (rp->tf_err);
568	case REG_RIP:
569		return (rp->tf_rip);
570	case REG_CS:
571		return (rp->tf_cs);
572	case REG_SS:
573		return (rp->tf_ss);
574	case REG_RFL:
575		return (rp->tf_rflags);
576	case REG_RSP:
577		return (rp->tf_rsp);
578	default:
579		DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
580		return (0);
581	}
582}
583
584static int
585dtrace_copycheck(uintptr_t uaddr, uintptr_t kaddr, size_t size)
586{
587	ASSERT(INKERNEL(kaddr) && kaddr + size >= kaddr);
588
589	if (uaddr + size > VM_MAXUSER_ADDRESS || uaddr + size < uaddr) {
590		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
591		cpu_core[curcpu].cpuc_dtrace_illval = uaddr;
592		return (0);
593	}
594
595	return (1);
596}
597
598void
599dtrace_copyin(uintptr_t uaddr, uintptr_t kaddr, size_t size,
600    volatile uint16_t *flags)
601{
602	if (dtrace_copycheck(uaddr, kaddr, size))
603		dtrace_copy(uaddr, kaddr, size);
604}
605
606void
607dtrace_copyout(uintptr_t kaddr, uintptr_t uaddr, size_t size,
608    volatile uint16_t *flags)
609{
610	if (dtrace_copycheck(uaddr, kaddr, size))
611		dtrace_copy(kaddr, uaddr, size);
612}
613
614void
615dtrace_copyinstr(uintptr_t uaddr, uintptr_t kaddr, size_t size,
616    volatile uint16_t *flags)
617{
618	if (dtrace_copycheck(uaddr, kaddr, size))
619		dtrace_copystr(uaddr, kaddr, size, flags);
620}
621
622void
623dtrace_copyoutstr(uintptr_t kaddr, uintptr_t uaddr, size_t size,
624    volatile uint16_t *flags)
625{
626	if (dtrace_copycheck(uaddr, kaddr, size))
627		dtrace_copystr(kaddr, uaddr, size, flags);
628}
629
630uint8_t
631dtrace_fuword8(void *uaddr)
632{
633	if ((uintptr_t)uaddr > VM_MAXUSER_ADDRESS) {
634		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
635		cpu_core[curcpu].cpuc_dtrace_illval = (uintptr_t)uaddr;
636		return (0);
637	}
638	return (dtrace_fuword8_nocheck(uaddr));
639}
640
641uint16_t
642dtrace_fuword16(void *uaddr)
643{
644	if ((uintptr_t)uaddr > VM_MAXUSER_ADDRESS) {
645		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
646		cpu_core[curcpu].cpuc_dtrace_illval = (uintptr_t)uaddr;
647		return (0);
648	}
649	return (dtrace_fuword16_nocheck(uaddr));
650}
651
652uint32_t
653dtrace_fuword32(void *uaddr)
654{
655	if ((uintptr_t)uaddr > VM_MAXUSER_ADDRESS) {
656		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
657		cpu_core[curcpu].cpuc_dtrace_illval = (uintptr_t)uaddr;
658		return (0);
659	}
660	return (dtrace_fuword32_nocheck(uaddr));
661}
662
663uint64_t
664dtrace_fuword64(void *uaddr)
665{
666	if ((uintptr_t)uaddr > VM_MAXUSER_ADDRESS) {
667		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
668		cpu_core[curcpu].cpuc_dtrace_illval = (uintptr_t)uaddr;
669		return (0);
670	}
671	return (dtrace_fuword64_nocheck(uaddr));
672}
673
674/*
675 * ifunc resolvers for SMAP support
676 */
677void dtrace_copy_nosmap(uintptr_t, uintptr_t, size_t);
678void dtrace_copy_smap(uintptr_t, uintptr_t, size_t);
679DEFINE_IFUNC(, void, dtrace_copy, (uintptr_t, uintptr_t, size_t))
680{
681
682	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
683	    dtrace_copy_smap : dtrace_copy_nosmap);
684}
685
686void dtrace_copystr_nosmap(uintptr_t, uintptr_t, size_t, volatile uint16_t *);
687void dtrace_copystr_smap(uintptr_t, uintptr_t, size_t, volatile uint16_t *);
688DEFINE_IFUNC(, void, dtrace_copystr, (uintptr_t, uintptr_t, size_t,
689    volatile uint16_t *))
690{
691
692	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
693	    dtrace_copystr_smap : dtrace_copystr_nosmap);
694}
695
696uintptr_t dtrace_fulword_nosmap(void *);
697uintptr_t dtrace_fulword_smap(void *);
698DEFINE_IFUNC(, uintptr_t, dtrace_fulword, (void *))
699{
700
701	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
702	    dtrace_fulword_smap : dtrace_fulword_nosmap);
703}
704
705uint8_t dtrace_fuword8_nocheck_nosmap(void *);
706uint8_t dtrace_fuword8_nocheck_smap(void *);
707DEFINE_IFUNC(, uint8_t, dtrace_fuword8_nocheck, (void *))
708{
709
710	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
711	    dtrace_fuword8_nocheck_smap : dtrace_fuword8_nocheck_nosmap);
712}
713
714uint16_t dtrace_fuword16_nocheck_nosmap(void *);
715uint16_t dtrace_fuword16_nocheck_smap(void *);
716DEFINE_IFUNC(, uint16_t, dtrace_fuword16_nocheck, (void *))
717{
718
719	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
720	    dtrace_fuword16_nocheck_smap : dtrace_fuword16_nocheck_nosmap);
721}
722
723uint32_t dtrace_fuword32_nocheck_nosmap(void *);
724uint32_t dtrace_fuword32_nocheck_smap(void *);
725DEFINE_IFUNC(, uint32_t, dtrace_fuword32_nocheck, (void *))
726{
727
728	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
729	    dtrace_fuword32_nocheck_smap : dtrace_fuword32_nocheck_nosmap);
730}
731
732uint64_t dtrace_fuword64_nocheck_nosmap(void *);
733uint64_t dtrace_fuword64_nocheck_smap(void *);
734DEFINE_IFUNC(, uint64_t, dtrace_fuword64_nocheck, (void *))
735{
736
737	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
738	    dtrace_fuword64_nocheck_smap : dtrace_fuword64_nocheck_nosmap);
739}
740