intel/dtrace/dtrace_isa.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2013, 2014 by Delphix. All rights reserved.
 * Copyright (c) 2017 Joyent, Inc.
 */

#include <sys/dtrace_impl.h>
#include <sys/stack.h>
#include <sys/frame.h>
#include <sys/cmn_err.h>
#include <sys/privregs.h>
#include <sys/sysmacros.h>

extern uintptr_t kernelbase;

int	dtrace_ustackdepth_max = 2048;

void
dtrace_getpcstack(pc_t *pcstack, int pcstack_limit, int aframes,
    uint32_t *intrpc)
{
	struct frame *fp = (struct frame *)dtrace_getfp();
	struct frame *nextfp, *minfp, *stacktop;
	int depth = 0;
	int on_intr, last = 0;
	uintptr_t pc;
	uintptr_t caller = CPU->cpu_dtrace_caller;

	if ((on_intr = CPU_ON_INTR(CPU)) != 0)
		stacktop = (struct frame *)(CPU->cpu_intr_stack + SA(MINFRAME));
	else
		stacktop = (struct frame *)curthread->t_stk;
	minfp = fp;

	aframes++;

	if (intrpc != NULL && depth < pcstack_limit)
		pcstack[depth++] = (pc_t)intrpc;

	while (depth < pcstack_limit) {
		nextfp = (struct frame *)fp->fr_savfp;
		pc = fp->fr_savpc;

		if (nextfp <= minfp || nextfp >= stacktop) {
			if (on_intr) {
				/*
				 * Hop from interrupt stack to thread stack.
				 */
				stacktop = (struct frame *)curthread->t_stk;
				minfp = (struct frame *)curthread->t_stkbase;
				on_intr = 0;
				continue;
			}

			/*
			 * This is the last frame we can process; indicate
			 * that we should return after processing this frame.
			 */
			last = 1;
		}

		if (aframes > 0) {
			if (--aframes == 0 && caller != NULL) {
				/*
				 * We've just run out of artificial frames,
				 * and we have a valid caller -- fill it in
				 * now.
				 */
				ASSERT(depth < pcstack_limit);
				pcstack[depth++] = (pc_t)caller;
				caller = NULL;
			}
		} else {
			if (depth < pcstack_limit)
				pcstack[depth++] = (pc_t)pc;
		}

		if (last) {
			while (depth < pcstack_limit)
				pcstack[depth++] = NULL;
			return;
		}

		fp = nextfp;
		minfp = fp;
	}
}

static int
dtrace_getustack_common(uint64_t *pcstack, int pcstack_limit, uintptr_t pc,
    uintptr_t sp)
{
	klwp_t *lwp = ttolwp(curthread);
	proc_t *p = curproc;
	uintptr_t oldcontext = lwp->lwp_oldcontext;
	uintptr_t oldsp;
	volatile uint16_t *flags =
	    (volatile uint16_t *)&cpu_core[CPU->cpu_id].cpuc_dtrace_flags;
	size_t s1, s2;
	int ret = 0;

	ASSERT(pcstack == NULL || pcstack_limit > 0);
	ASSERT(dtrace_ustackdepth_max > 0);

	if (p->p_model == DATAMODEL_NATIVE) {
		s1 = sizeof (struct frame) + 2 * sizeof (long);
		s2 = s1 + sizeof (siginfo_t);
	} else {
		s1 = sizeof (struct frame32) + 3 * sizeof (int);
		s2 = s1 + sizeof (siginfo32_t);
	}

	while (pc != 0) {
		/*
		 * We limit the number of times we can go around this
		 * loop to account for a circular stack.
		 */
		if (ret++ >= dtrace_ustackdepth_max) {
			*flags |= CPU_DTRACE_BADSTACK;
			cpu_core[CPU->cpu_id].cpuc_dtrace_illval = sp;
			break;
		}

		if (pcstack != NULL) {
			*pcstack++ = (uint64_t)pc;
			pcstack_limit--;
			if (pcstack_limit <= 0)
				break;
		}

		if (sp == 0)
			break;

		oldsp = sp;

		if (oldcontext == sp + s1 || oldcontext == sp + s2) {
			if (p->p_model == DATAMODEL_NATIVE) {
				ucontext_t *ucp = (ucontext_t *)oldcontext;
				greg_t *gregs = ucp->uc_mcontext.gregs;

				sp = dtrace_fulword(&gregs[REG_FP]);
				pc = dtrace_fulword(&gregs[REG_PC]);

				oldcontext = dtrace_fulword(&ucp->uc_link);
			} else {
				ucontext32_t *ucp = (ucontext32_t *)oldcontext;
				greg32_t *gregs = ucp->uc_mcontext.gregs;

				sp = dtrace_fuword32(&gregs[EBP]);
				pc = dtrace_fuword32(&gregs[EIP]);

				oldcontext = dtrace_fuword32(&ucp->uc_link);
			}
		} else {
			if (p->p_model == DATAMODEL_NATIVE) {
				struct frame *fr = (struct frame *)sp;

				pc = dtrace_fulword(&fr->fr_savpc);
				sp = dtrace_fulword(&fr->fr_savfp);
			} else {
				struct frame32 *fr = (struct frame32 *)sp;

				pc = dtrace_fuword32(&fr->fr_savpc);
				sp = dtrace_fuword32(&fr->fr_savfp);
			}
		}

		if (sp == oldsp) {
			*flags |= CPU_DTRACE_BADSTACK;
			cpu_core[CPU->cpu_id].cpuc_dtrace_illval = sp;
			break;
		}

		/*
		 * This is totally bogus:  if we faulted, we're going to clear
		 * the fault and break.  This is to deal with the apparently
		 * broken Java stacks on x86.
		 */
		if (*flags & CPU_DTRACE_FAULT) {
			*flags &= ~CPU_DTRACE_FAULT;
			break;
		}
	}

	return (ret);
}

void
dtrace_getupcstack(uint64_t *pcstack, int pcstack_limit)
{
	klwp_t *lwp = ttolwp(curthread);
	proc_t *p = curproc;
	struct regs *rp;
	uintptr_t pc, sp;
	int n;

	ASSERT(DTRACE_CPUFLAG_ISSET(CPU_DTRACE_NOFAULT));

	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_FAULT))
		return;

	if (pcstack_limit <= 0)
		return;

	/*
	 * If there's no user context we still need to zero the stack.
	 */
	if (lwp == NULL || p == NULL || (rp = lwp->lwp_regs) == NULL)
		goto zero;

	*pcstack++ = (uint64_t)p->p_pid;
	pcstack_limit--;

	if (pcstack_limit <= 0)
		return;

	pc = rp->r_pc;
	sp = rp->r_fp;

	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_ENTRY)) {
		*pcstack++ = (uint64_t)pc;
		pcstack_limit--;
		if (pcstack_limit <= 0)
			return;

		if (p->p_model == DATAMODEL_NATIVE)
			pc = dtrace_fulword((void *)rp->r_sp);
		else
			pc = dtrace_fuword32((void *)rp->r_sp);
	}

	n = dtrace_getustack_common(pcstack, pcstack_limit, pc, sp);
	ASSERT(n >= 0);
	ASSERT(n <= pcstack_limit);

	pcstack += n;
	pcstack_limit -= n;

zero:
	while (pcstack_limit-- > 0)
		*pcstack++ = NULL;
}

int
dtrace_getustackdepth(void)
{
	klwp_t *lwp = ttolwp(curthread);
	proc_t *p = curproc;
	struct regs *rp;
	uintptr_t pc, sp;
	int n = 0;

	if (lwp == NULL || p == NULL || (rp = lwp->lwp_regs) == NULL)
		return (0);

	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_FAULT))
		return (-1);

	pc = rp->r_pc;
	sp = rp->r_fp;

	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_ENTRY)) {
		n++;

		if (p->p_model == DATAMODEL_NATIVE)
			pc = dtrace_fulword((void *)rp->r_sp);
		else
			pc = dtrace_fuword32((void *)rp->r_sp);
	}

	n += dtrace_getustack_common(NULL, 0, pc, sp);

	return (n);
}

void
dtrace_getufpstack(uint64_t *pcstack, uint64_t *fpstack, int pcstack_limit)
{
	klwp_t *lwp = ttolwp(curthread);
	proc_t *p = curproc;
	struct regs *rp;
	uintptr_t pc, sp, oldcontext;
	volatile uint16_t *flags =
	    (volatile uint16_t *)&cpu_core[CPU->cpu_id].cpuc_dtrace_flags;
	size_t s1, s2;

	if (*flags & CPU_DTRACE_FAULT)
		return;

	if (pcstack_limit <= 0)
		return;

	/*
	 * If there's no user context we still need to zero the stack.
	 */
	if (lwp == NULL || p == NULL || (rp = lwp->lwp_regs) == NULL)
		goto zero;

	*pcstack++ = (uint64_t)p->p_pid;
	pcstack_limit--;

	if (pcstack_limit <= 0)
		return;

	pc = rp->r_pc;
	sp = rp->r_fp;
	oldcontext = lwp->lwp_oldcontext;

	if (p->p_model == DATAMODEL_NATIVE) {
		s1 = sizeof (struct frame) + 2 * sizeof (long);
		s2 = s1 + sizeof (siginfo_t);
	} else {
		s1 = sizeof (struct frame32) + 3 * sizeof (int);
		s2 = s1 + sizeof (siginfo32_t);
	}

	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_ENTRY)) {
		*pcstack++ = (uint64_t)pc;
		*fpstack++ = 0;
		pcstack_limit--;
		if (pcstack_limit <= 0)
			return;

		if (p->p_model == DATAMODEL_NATIVE)
			pc = dtrace_fulword((void *)rp->r_sp);
		else
			pc = dtrace_fuword32((void *)rp->r_sp);
	}

	while (pc != 0) {
		*pcstack++ = (uint64_t)pc;
		*fpstack++ = sp;
		pcstack_limit--;
		if (pcstack_limit <= 0)
			break;

		if (sp == 0)
			break;

		if (oldcontext == sp + s1 || oldcontext == sp + s2) {
			if (p->p_model == DATAMODEL_NATIVE) {
				ucontext_t *ucp = (ucontext_t *)oldcontext;
				greg_t *gregs = ucp->uc_mcontext.gregs;

				sp = dtrace_fulword(&gregs[REG_FP]);
				pc = dtrace_fulword(&gregs[REG_PC]);

				oldcontext = dtrace_fulword(&ucp->uc_link);
			} else {
				ucontext_t *ucp = (ucontext_t *)oldcontext;
				greg_t *gregs = ucp->uc_mcontext.gregs;

				sp = dtrace_fuword32(&gregs[EBP]);
				pc = dtrace_fuword32(&gregs[EIP]);

				oldcontext = dtrace_fuword32(&ucp->uc_link);
			}
		} else {
			if (p->p_model == DATAMODEL_NATIVE) {
				struct frame *fr = (struct frame *)sp;

				pc = dtrace_fulword(&fr->fr_savpc);
				sp = dtrace_fulword(&fr->fr_savfp);
			} else {
				struct frame32 *fr = (struct frame32 *)sp;

				pc = dtrace_fuword32(&fr->fr_savpc);
				sp = dtrace_fuword32(&fr->fr_savfp);
			}
		}

		/*
		 * This is totally bogus:  if we faulted, we're going to clear
		 * the fault and break.  This is to deal with the apparently
		 * broken Java stacks on x86.
		 */
		if (*flags & CPU_DTRACE_FAULT) {
			*flags &= ~CPU_DTRACE_FAULT;
			break;
		}
	}

zero:
	while (pcstack_limit-- > 0)
		*pcstack++ = NULL;
}

/*ARGSUSED*/
uint64_t
dtrace_getarg(int arg, int aframes)
{
	uintptr_t val;
	struct frame *fp = (struct frame *)dtrace_getfp();
	uintptr_t *stack;
	int i;
#if defined(__amd64)
	/*
	 * A total of 6 arguments are passed via registers; any argument with
	 * index of 5 or lower is therefore in a register.
	 */
	int inreg = 5;
#endif

	for (i = 1; i <= aframes; i++) {
		fp = (struct frame *)(fp->fr_savfp);

		if (fp->fr_savpc == (pc_t)dtrace_invop_callsite) {
#if !defined(__amd64)
			/*
			 * If we pass through the invalid op handler, we will
			 * use the pointer that it passed to the stack as the
			 * second argument to dtrace_invop() as the pointer to
			 * the stack.  When using this stack, we must step
			 * beyond the EIP that was pushed when the trap was
			 * taken -- hence the "+ 1" below.
			 */
			stack = ((uintptr_t **)&fp[1])[1] + 1;
#else
			/*
			 * In the case of amd64, we will use the pointer to the
			 * regs structure that was pushed when we took the
			 * trap.  To get this structure, we must increment
			 * beyond the frame structure, the calling RIP, and
			 * padding stored in dtrace_invop().  If the argument
			 * that we're seeking is passed on the stack, we'll
			 * pull the true stack pointer out of the saved
			 * registers and decrement our argument by the number
			 * of arguments passed in registers; if the argument
			 * we're seeking is passed in regsiters, we can just
			 * load it directly.
			 */
			struct regs *rp = (struct regs *)((uintptr_t)&fp[1] +
			    sizeof (uintptr_t) * 2);

			if (arg <= inreg) {
				stack = (uintptr_t *)&rp->r_rdi;
			} else {
				stack = (uintptr_t *)(rp->r_rsp);
				arg -= inreg;
			}
#endif
			goto load;
		}

	}

	/*
	 * We know that we did not come through a trap to get into
	 * dtrace_probe() -- the provider simply called dtrace_probe()
	 * directly.  As this is the case, we need to shift the argument
	 * that we're looking for:  the probe ID is the first argument to
	 * dtrace_probe(), so the argument n will actually be found where
	 * one would expect to find argument (n + 1).
	 */
	arg++;

#if defined(__amd64)
	if (arg <= inreg) {
		/*
		 * This shouldn't happen.  If the argument is passed in a
		 * register then it should have been, well, passed in a
		 * register...
		 */
		DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
		return (0);
	}

	arg -= (inreg + 1);
#endif
	stack = (uintptr_t *)&fp[1];

load:
	DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
	val = stack[arg];
	DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);

	return (val);
}

/*ARGSUSED*/
int
dtrace_getstackdepth(int aframes)
{
	struct frame *fp = (struct frame *)dtrace_getfp();
	struct frame *nextfp, *minfp, *stacktop;
	int depth = 0;
	int on_intr;

	if ((on_intr = CPU_ON_INTR(CPU)) != 0)
		stacktop = (struct frame *)(CPU->cpu_intr_stack + SA(MINFRAME));
	else
		stacktop = (struct frame *)curthread->t_stk;
	minfp = fp;

	aframes++;

	for (;;) {
		depth++;

		nextfp = (struct frame *)fp->fr_savfp;

		if (nextfp <= minfp || nextfp >= stacktop) {
			if (on_intr) {
				/*
				 * Hop from interrupt stack to thread stack.
				 */
				stacktop = (struct frame *)curthread->t_stk;
				minfp = (struct frame *)curthread->t_stkbase;
				on_intr = 0;
				continue;
			}
			break;
		}

		fp = nextfp;
		minfp = fp;
	}

	if (depth <= aframes)
		return (0);

	return (depth - aframes);
}

#if defined(__amd64)
static const int dtrace_regmap[] = {
	REG_GS,		/* GS */
	REG_FS,		/* FS */
	REG_ES,		/* ES */
	REG_DS,		/* DS */
	REG_RDI,	/* EDI */
	REG_RSI,	/* ESI */
	REG_RBP,	/* EBP */
	REG_RSP,	/* ESP */
	REG_RBX,	/* EBX */
	REG_RDX,	/* EDX */
	REG_RCX,	/* ECX */
	REG_RAX,	/* EAX */
	REG_TRAPNO,	/* TRAPNO */
	REG_ERR,	/* ERR */
	REG_RIP,	/* EIP */
	REG_CS,		/* CS */
	REG_RFL,	/* EFL */
	REG_RSP,	/* UESP */
	REG_SS		/* SS */
};
#endif


ulong_t
dtrace_getreg(struct regs *rp, uint_t reg)
{
#if defined(__amd64)
	if (reg <= SS) {
		if (reg >= sizeof (dtrace_regmap) / sizeof (int)) {
			DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
			return (0);
		}

		reg = dtrace_regmap[reg];
	} else {
		reg -= SS + 1;
	}

	switch (reg) {
	case REG_RDI:
		return (rp->r_rdi);
	case REG_RSI:
		return (rp->r_rsi);
	case REG_RDX:
		return (rp->r_rdx);
	case REG_RCX:
		return (rp->r_rcx);
	case REG_R8:
		return (rp->r_r8);
	case REG_R9:
		return (rp->r_r9);
	case REG_RAX:
		return (rp->r_rax);
	case REG_RBX:
		return (rp->r_rbx);
	case REG_RBP:
		return (rp->r_rbp);
	case REG_R10:
		return (rp->r_r10);
	case REG_R11:
		return (rp->r_r11);
	case REG_R12:
		return (rp->r_r12);
	case REG_R13:
		return (rp->r_r13);
	case REG_R14:
		return (rp->r_r14);
	case REG_R15:
		return (rp->r_r15);
	case REG_DS:
		return (rp->r_ds);
	case REG_ES:
		return (rp->r_es);
	case REG_FS:
		return (rp->r_fs);
	case REG_GS:
		return (rp->r_gs);
	case REG_TRAPNO:
		return (rp->r_trapno);
	case REG_ERR:
		return (rp->r_err);
	case REG_RIP:
		return (rp->r_rip);
	case REG_CS:
		return (rp->r_cs);
	case REG_SS:
		return (rp->r_ss);
	case REG_RFL:
		return (rp->r_rfl);
	case REG_RSP:
		return (rp->r_rsp);
	default:
		DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
		return (0);
	}

#else
	if (reg > SS) {
		DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
		return (0);
	}

	return ((&rp->r_gs)[reg]);
#endif
}

void
dtrace_setreg(struct regs *rp, uint_t reg, ulong_t val)
{
#if defined(__amd64)
	if (reg <= SS) {
		ASSERT(reg < (sizeof (dtrace_regmap) / sizeof (int)));

		reg = dtrace_regmap[reg];
	} else {
		reg -= SS + 1;
	}

	switch (reg) {
	case REG_RDI:
		rp->r_rdi = val;
		break;
	case REG_RSI:
		rp->r_rsi = val;
		break;
	case REG_RDX:
		rp->r_rdx = val;
		break;
	case REG_RCX:
		rp->r_rcx = val;
		break;
	case REG_R8:
		rp->r_r8 = val;
		break;
	case REG_R9:
		rp->r_r9 = val;
		break;
	case REG_RAX:
		rp->r_rax = val;
		break;
	case REG_RBX:
		rp->r_rbx = val;
		break;
	case REG_RBP:
		rp->r_rbp = val;
		break;
	case REG_R10:
		rp->r_r10 = val;
		break;
	case REG_R11:
		rp->r_r11 = val;
		break;
	case REG_R12:
		rp->r_r12 = val;
		break;
	case REG_R13:
		rp->r_r13 = val;
		break;
	case REG_R14:
		rp->r_r14 = val;
		break;
	case REG_R15:
		rp->r_r15 = val;
		break;
	case REG_RSP:
		rp->r_rsp = val;
		break;
	default:
		DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
		return;
	}

#else /* defined(__amd64) */
	switch (reg) {
	case EAX:
		rp->r_eax = val;
		break;
	case ECX:
		rp->r_ecx = val;
		break;
	case EDX:
		rp->r_edx = val;
		break;
	case EBX:
		rp->r_ebx = val;
		break;
	case ESP:
		rp->r_esp = val;
		break;
	case EBP:
		rp->r_ebp = val;
		break;
	case ESI:
		rp->r_esi = val;
		break;
	case EDI:
		rp->r_edi = val;
		break;
	default:
		DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
		return;
	}
#endif /* defined(__amd64) */
}

static int
dtrace_copycheck(uintptr_t uaddr, uintptr_t kaddr, size_t size)
{
	ASSERT(kaddr >= kernelbase && kaddr + size >= kaddr);

	if (uaddr + size >= kernelbase || uaddr + size < uaddr) {
		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
		cpu_core[CPU->cpu_id].cpuc_dtrace_illval = uaddr;
		return (0);
	}

	return (1);
}

/*ARGSUSED*/
void
dtrace_copyin(uintptr_t uaddr, uintptr_t kaddr, size_t size,
    volatile uint16_t *flags)
{
	if (dtrace_copycheck(uaddr, kaddr, size))
		dtrace_copy(uaddr, kaddr, size);
}

/*ARGSUSED*/
void
dtrace_copyout(uintptr_t kaddr, uintptr_t uaddr, size_t size,
    volatile uint16_t *flags)
{
	if (dtrace_copycheck(uaddr, kaddr, size))
		dtrace_copy(kaddr, uaddr, size);
}

void
dtrace_copyinstr(uintptr_t uaddr, uintptr_t kaddr, size_t size,
    volatile uint16_t *flags)
{
	if (dtrace_copycheck(uaddr, kaddr, size))
		dtrace_copystr(uaddr, kaddr, size, flags);
}

void
dtrace_copyoutstr(uintptr_t kaddr, uintptr_t uaddr, size_t size,
    volatile uint16_t *flags)
{
	if (dtrace_copycheck(uaddr, kaddr, size))
		dtrace_copystr(kaddr, uaddr, size, flags);
}

uint8_t
dtrace_fuword8(void *uaddr)
{
	extern uint8_t dtrace_fuword8_nocheck(void *);
	if ((uintptr_t)uaddr >= _userlimit) {
		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
		cpu_core[CPU->cpu_id].cpuc_dtrace_illval = (uintptr_t)uaddr;
		return (0);
	}
	return (dtrace_fuword8_nocheck(uaddr));
}

uint16_t
dtrace_fuword16(void *uaddr)
{
	extern uint16_t dtrace_fuword16_nocheck(void *);
	if ((uintptr_t)uaddr >= _userlimit) {
		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
		cpu_core[CPU->cpu_id].cpuc_dtrace_illval = (uintptr_t)uaddr;
		return (0);
	}
	return (dtrace_fuword16_nocheck(uaddr));
}

uint32_t
dtrace_fuword32(void *uaddr)
{
	extern uint32_t dtrace_fuword32_nocheck(void *);
	if ((uintptr_t)uaddr >= _userlimit) {
		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
		cpu_core[CPU->cpu_id].cpuc_dtrace_illval = (uintptr_t)uaddr;
		return (0);
	}
	return (dtrace_fuword32_nocheck(uaddr));
}

uint64_t
dtrace_fuword64(void *uaddr)
{
	extern uint64_t dtrace_fuword64_nocheck(void *);
	if ((uintptr_t)uaddr >= _userlimit) {
		DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
		cpu_core[CPU->cpu_id].cpuc_dtrace_illval = (uintptr_t)uaddr;
		return (0);
	}
	return (dtrace_fuword64_nocheck(uaddr));
}