amd64: move signal handling and register structures manipulations into exec_machdep.c

from machdep.c which is too large pile of unrelated things.
Some ptrace functions are moved from machdep.c to ptrace_machdep.c.

Now machdep.c contains code mostly related to the low level initialization
and regular low level operation of the architecture, while signal MD code
and registers handling is placed in exec_machdep.c.

Reviewed by:	jhb, markj
Discussed with:	jrtc27
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D31954

4 files changed, 1021 insertions, 924 deletions

diff --git a/sys/amd64/amd64/exec_machdep.c b/sys/amd64/amd64/exec_machdep.c
new file mode 100644
index 000000000000..5cd905e1051b
--- /dev/null
+++ b/sys/amd64/amd64/exec_machdep.c
@@ -0,0 +1,987 @@
+/*-
+ * SPDX-License-Identifier: BSD-4-Clause
+ *
+ * Copyright (c) 2003 Peter Wemm.
+ * Copyright (c) 1992 Terrence R. Lambert.
+ * Copyright (c) 1982, 1987, 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * William Jolitz.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 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: @(#)machdep.c	7.4 (Berkeley) 6/3/91
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "opt_cpu.h"
+#include "opt_ddb.h"
+#include "opt_kstack_pages.h"
+
+#include <sys/param.h>
+#include <sys/proc.h>
+#include <sys/systm.h>
+#include <sys/exec.h>
+#include <sys/imgact.h>
+#include <sys/kdb.h>
+#include <sys/kernel.h>
+#include <sys/ktr.h>
+#include <sys/linker.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/pcpu.h>
+#include <sys/reg.h>
+#include <sys/rwlock.h>
+#include <sys/signalvar.h>
+#ifdef SMP
+#include <sys/smp.h>
+#endif
+#include <sys/syscallsubr.h>
+#include <sys/sysctl.h>
+#include <sys/sysent.h>
+#include <sys/sysproto.h>
+#include <sys/ucontext.h>
+#include <sys/vmmeter.h>
+
+#include <vm/vm.h>
+#include <vm/vm_param.h>
+#include <vm/vm_extern.h>
+#include <vm/pmap.h>
+
+#ifdef DDB
+#ifndef KDB
+#error KDB must be enabled in order for DDB to work!
+#endif
+#include <ddb/ddb.h>
+#include <ddb/db_sym.h>
+#endif
+
+#include <machine/vmparam.h>
+#include <machine/frame.h>
+#include <machine/md_var.h>
+#include <machine/pcb.h>
+#include <machine/proc.h>
+#include <machine/sigframe.h>
+#include <machine/specialreg.h>
+#include <machine/trap.h>
+
+static void get_fpcontext(struct thread *td, mcontext_t *mcp,
+    char *xfpusave, size_t xfpusave_len);
+static int  set_fpcontext(struct thread *td, mcontext_t *mcp,
+    char *xfpustate, size_t xfpustate_len);
+
+/*
+ * Send an interrupt to process.
+ *
+ * Stack is set up to allow sigcode stored at top to call routine,
+ * followed by call to sigreturn routine below.  After sigreturn
+ * resets the signal mask, the stack, and the frame pointer, it
+ * returns to the user specified pc, psl.
+ */
+void
+sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+{
+	struct sigframe sf, *sfp;
+	struct pcb *pcb;
+	struct proc *p;
+	struct thread *td;
+	struct sigacts *psp;
+	char *sp;
+	struct trapframe *regs;
+	char *xfpusave;
+	size_t xfpusave_len;
+	int sig;
+	int oonstack;
+
+	td = curthread;
+	pcb = td->td_pcb;
+	p = td->td_proc;
+	PROC_LOCK_ASSERT(p, MA_OWNED);
+	sig = ksi->ksi_signo;
+	psp = p->p_sigacts;
+	mtx_assert(&psp->ps_mtx, MA_OWNED);
+	regs = td->td_frame;
+	oonstack = sigonstack(regs->tf_rsp);
+
+	if (cpu_max_ext_state_size > sizeof(struct savefpu) && use_xsave) {
+		xfpusave_len = cpu_max_ext_state_size - sizeof(struct savefpu);
+		xfpusave = __builtin_alloca(xfpusave_len);
+	} else {
+		xfpusave_len = 0;
+		xfpusave = NULL;
+	}
+
+	/* Save user context. */
+	bzero(&sf, sizeof(sf));
+	sf.sf_uc.uc_sigmask = *mask;
+	sf.sf_uc.uc_stack = td->td_sigstk;
+	sf.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
+	    ? ((oonstack) ? SS_ONSTACK : 0) : SS_DISABLE;
+	sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
+	bcopy(regs, &sf.sf_uc.uc_mcontext.mc_rdi, sizeof(*regs));
+	sf.sf_uc.uc_mcontext.mc_len = sizeof(sf.sf_uc.uc_mcontext); /* magic */
+	get_fpcontext(td, &sf.sf_uc.uc_mcontext, xfpusave, xfpusave_len);
+	fpstate_drop(td);
+	update_pcb_bases(pcb);
+	sf.sf_uc.uc_mcontext.mc_fsbase = pcb->pcb_fsbase;
+	sf.sf_uc.uc_mcontext.mc_gsbase = pcb->pcb_gsbase;
+	bzero(sf.sf_uc.uc_mcontext.mc_spare,
+	    sizeof(sf.sf_uc.uc_mcontext.mc_spare));
+
+	/* Allocate space for the signal handler context. */
+	if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
+	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
+		sp = (char *)td->td_sigstk.ss_sp + td->td_sigstk.ss_size;
+#if defined(COMPAT_43)
+		td->td_sigstk.ss_flags |= SS_ONSTACK;
+#endif
+	} else
+		sp = (char *)regs->tf_rsp - 128;
+	if (xfpusave != NULL) {
+		sp -= xfpusave_len;
+		sp = (char *)((unsigned long)sp & ~0x3Ful);
+		sf.sf_uc.uc_mcontext.mc_xfpustate = (register_t)sp;
+	}
+	sp -= sizeof(struct sigframe);
+	/* Align to 16 bytes. */
+	sfp = (struct sigframe *)((unsigned long)sp & ~0xFul);
+
+	/* Build the argument list for the signal handler. */
+	regs->tf_rdi = sig;			/* arg 1 in %rdi */
+	regs->tf_rdx = (register_t)&sfp->sf_uc;	/* arg 3 in %rdx */
+	bzero(&sf.sf_si, sizeof(sf.sf_si));
+	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+		/* Signal handler installed with SA_SIGINFO. */
+		regs->tf_rsi = (register_t)&sfp->sf_si;	/* arg 2 in %rsi */
+		sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;
+
+		/* Fill in POSIX parts */
+		sf.sf_si = ksi->ksi_info;
+		sf.sf_si.si_signo = sig; /* maybe a translated signal */
+		regs->tf_rcx = (register_t)ksi->ksi_addr; /* arg 4 in %rcx */
+	} else {
+		/* Old FreeBSD-style arguments. */
+		regs->tf_rsi = ksi->ksi_code;	/* arg 2 in %rsi */
+		regs->tf_rcx = (register_t)ksi->ksi_addr; /* arg 4 in %rcx */
+		sf.sf_ahu.sf_handler = catcher;
+	}
+	mtx_unlock(&psp->ps_mtx);
+	PROC_UNLOCK(p);
+
+	/*
+	 * Copy the sigframe out to the user's stack.
+	 */
+	if (copyout(&sf, sfp, sizeof(*sfp)) != 0 ||
+	    (xfpusave != NULL && copyout(xfpusave,
+	    (void *)sf.sf_uc.uc_mcontext.mc_xfpustate, xfpusave_len)
+	    != 0)) {
+#ifdef DEBUG
+		printf("process %ld has trashed its stack\n", (long)p->p_pid);
+#endif
+		PROC_LOCK(p);
+		sigexit(td, SIGILL);
+	}
+
+	regs->tf_rsp = (long)sfp;
+	regs->tf_rip = p->p_sysent->sv_sigcode_base;
+	regs->tf_rflags &= ~(PSL_T | PSL_D);
+	regs->tf_cs = _ucodesel;
+	regs->tf_ds = _udatasel;
+	regs->tf_ss = _udatasel;
+	regs->tf_es = _udatasel;
+	regs->tf_fs = _ufssel;
+	regs->tf_gs = _ugssel;
+	regs->tf_flags = TF_HASSEGS;
+	PROC_LOCK(p);
+	mtx_lock(&psp->ps_mtx);
+}
+
+/*
+ * System call to cleanup state after a signal
+ * has been taken.  Reset signal mask and
+ * stack state from context left by sendsig (above).
+ * Return to previous pc and psl as specified by
+ * context left by sendsig. Check carefully to
+ * make sure that the user has not modified the
+ * state to gain improper privileges.
+ */
+int
+sys_sigreturn(td, uap)
+	struct thread *td;
+	struct sigreturn_args /* {
+		const struct __ucontext *sigcntxp;
+	} */ *uap;
+{
+	ucontext_t uc;
+	struct pcb *pcb;
+	struct proc *p;
+	struct trapframe *regs;
+	ucontext_t *ucp;
+	char *xfpustate;
+	size_t xfpustate_len;
+	long rflags;
+	int cs, error, ret;
+	ksiginfo_t ksi;
+
+	pcb = td->td_pcb;
+	p = td->td_proc;
+
+	error = copyin(uap->sigcntxp, &uc, sizeof(uc));
+	if (error != 0) {
+		uprintf("pid %d (%s): sigreturn copyin failed\n",
+		    p->p_pid, td->td_name);
+		return (error);
+	}
+	ucp = &uc;
+	if ((ucp->uc_mcontext.mc_flags & ~_MC_FLAG_MASK) != 0) {
+		uprintf("pid %d (%s): sigreturn mc_flags %x\n", p->p_pid,
+		    td->td_name, ucp->uc_mcontext.mc_flags);
+		return (EINVAL);
+	}
+	regs = td->td_frame;
+	rflags = ucp->uc_mcontext.mc_rflags;
+	/*
+	 * Don't allow users to change privileged or reserved flags.
+	 */
+	if (!EFL_SECURE(rflags, regs->tf_rflags)) {
+		uprintf("pid %d (%s): sigreturn rflags = 0x%lx\n", p->p_pid,
+		    td->td_name, rflags);
+		return (EINVAL);
+	}
+
+	/*
+	 * Don't allow users to load a valid privileged %cs.  Let the
+	 * hardware check for invalid selectors, excess privilege in
+	 * other selectors, invalid %eip's and invalid %esp's.
+	 */
+	cs = ucp->uc_mcontext.mc_cs;
+	if (!CS_SECURE(cs)) {
+		uprintf("pid %d (%s): sigreturn cs = 0x%x\n", p->p_pid,
+		    td->td_name, cs);
+		ksiginfo_init_trap(&ksi);
+		ksi.ksi_signo = SIGBUS;
+		ksi.ksi_code = BUS_OBJERR;
+		ksi.ksi_trapno = T_PROTFLT;
+		ksi.ksi_addr = (void *)regs->tf_rip;
+		trapsignal(td, &ksi);
+		return (EINVAL);
+	}
+
+	if ((uc.uc_mcontext.mc_flags & _MC_HASFPXSTATE) != 0) {
+		xfpustate_len = uc.uc_mcontext.mc_xfpustate_len;
+		if (xfpustate_len > cpu_max_ext_state_size -
+		    sizeof(struct savefpu)) {
+			uprintf("pid %d (%s): sigreturn xfpusave_len = 0x%zx\n",
+			    p->p_pid, td->td_name, xfpustate_len);
+			return (EINVAL);
+		}
+		xfpustate = __builtin_alloca(xfpustate_len);
+		error = copyin((const void *)uc.uc_mcontext.mc_xfpustate,
+		    xfpustate, xfpustate_len);
+		if (error != 0) {
+			uprintf(
+	"pid %d (%s): sigreturn copying xfpustate failed\n",
+			    p->p_pid, td->td_name);
+			return (error);
+		}
+	} else {
+		xfpustate = NULL;
+		xfpustate_len = 0;
+	}
+	ret = set_fpcontext(td, &ucp->uc_mcontext, xfpustate, xfpustate_len);
+	if (ret != 0) {
+		uprintf("pid %d (%s): sigreturn set_fpcontext err %d\n",
+		    p->p_pid, td->td_name, ret);
+		return (ret);
+	}
+	bcopy(&ucp->uc_mcontext.mc_rdi, regs, sizeof(*regs));
+	update_pcb_bases(pcb);
+	pcb->pcb_fsbase = ucp->uc_mcontext.mc_fsbase;
+	pcb->pcb_gsbase = ucp->uc_mcontext.mc_gsbase;
+
+#if defined(COMPAT_43)
+	if (ucp->uc_mcontext.mc_onstack & 1)
+		td->td_sigstk.ss_flags |= SS_ONSTACK;
+	else
+		td->td_sigstk.ss_flags &= ~SS_ONSTACK;
+#endif
+
+	kern_sigprocmask(td, SIG_SETMASK, &ucp->uc_sigmask, NULL, 0);
+	return (EJUSTRETURN);
+}
+
+#ifdef COMPAT_FREEBSD4
+int
+freebsd4_sigreturn(struct thread *td, struct freebsd4_sigreturn_args *uap)
+{
+
+	return sys_sigreturn(td, (struct sigreturn_args *)uap);
+}
+#endif
+
+/*
+ * Reset the hardware debug registers if they were in use.
+ * They won't have any meaning for the newly exec'd process.
+ */
+void
+x86_clear_dbregs(struct pcb *pcb)
+{
+	if ((pcb->pcb_flags & PCB_DBREGS) == 0)
+		return;
+
+	pcb->pcb_dr0 = 0;
+	pcb->pcb_dr1 = 0;
+	pcb->pcb_dr2 = 0;
+	pcb->pcb_dr3 = 0;
+	pcb->pcb_dr6 = 0;
+	pcb->pcb_dr7 = 0;
+
+	if (pcb == curpcb) {
+		/*
+		 * Clear the debug registers on the running CPU,
+		 * otherwise they will end up affecting the next
+		 * process we switch to.
+		 */
+		reset_dbregs();
+	}
+	clear_pcb_flags(pcb, PCB_DBREGS);
+}
+
+/*
+ * Reset registers to default values on exec.
+ */
+void
+exec_setregs(struct thread *td, struct image_params *imgp, uintptr_t stack)
+{
+	struct trapframe *regs;
+	struct pcb *pcb;
+	register_t saved_rflags;
+
+	regs = td->td_frame;
+	pcb = td->td_pcb;
+
+	if (td->td_proc->p_md.md_ldt != NULL)
+		user_ldt_free(td);
+
+	update_pcb_bases(pcb);
+	pcb->pcb_fsbase = 0;
+	pcb->pcb_gsbase = 0;
+	clear_pcb_flags(pcb, PCB_32BIT);
+	pcb->pcb_initial_fpucw = __INITIAL_FPUCW__;
+
+	saved_rflags = regs->tf_rflags & PSL_T;
+	bzero((char *)regs, sizeof(struct trapframe));
+	regs->tf_rip = imgp->entry_addr;
+	regs->tf_rsp = ((stack - 8) & ~0xFul) + 8;
+	regs->tf_rdi = stack;		/* argv */
+	regs->tf_rflags = PSL_USER | saved_rflags;
+	regs->tf_ss = _udatasel;
+	regs->tf_cs = _ucodesel;
+	regs->tf_ds = _udatasel;
+	regs->tf_es = _udatasel;
+	regs->tf_fs = _ufssel;
+	regs->tf_gs = _ugssel;
+	regs->tf_flags = TF_HASSEGS;
+
+	x86_clear_dbregs(pcb);
+
+	/*
+	 * Drop the FP state if we hold it, so that the process gets a
+	 * clean FP state if it uses the FPU again.
+	 */
+	fpstate_drop(td);
+}
+
+int
+fill_regs(struct thread *td, struct reg *regs)
+{
+	struct trapframe *tp;
+
+	tp = td->td_frame;
+	return (fill_frame_regs(tp, regs));
+}
+
+int
+fill_frame_regs(struct trapframe *tp, struct reg *regs)
+{
+
+	regs->r_r15 = tp->tf_r15;
+	regs->r_r14 = tp->tf_r14;
+	regs->r_r13 = tp->tf_r13;
+	regs->r_r12 = tp->tf_r12;
+	regs->r_r11 = tp->tf_r11;
+	regs->r_r10 = tp->tf_r10;
+	regs->r_r9  = tp->tf_r9;
+	regs->r_r8  = tp->tf_r8;
+	regs->r_rdi = tp->tf_rdi;
+	regs->r_rsi = tp->tf_rsi;
+	regs->r_rbp = tp->tf_rbp;
+	regs->r_rbx = tp->tf_rbx;
+	regs->r_rdx = tp->tf_rdx;
+	regs->r_rcx = tp->tf_rcx;
+	regs->r_rax = tp->tf_rax;
+	regs->r_rip = tp->tf_rip;
+	regs->r_cs = tp->tf_cs;
+	regs->r_rflags = tp->tf_rflags;
+	regs->r_rsp = tp->tf_rsp;
+	regs->r_ss = tp->tf_ss;
+	if (tp->tf_flags & TF_HASSEGS) {
+		regs->r_ds = tp->tf_ds;
+		regs->r_es = tp->tf_es;
+		regs->r_fs = tp->tf_fs;
+		regs->r_gs = tp->tf_gs;
+	} else {
+		regs->r_ds = 0;
+		regs->r_es = 0;
+		regs->r_fs = 0;
+		regs->r_gs = 0;
+	}
+	regs->r_err = 0;
+	regs->r_trapno = 0;
+	return (0);
+}
+
+int
+set_regs(struct thread *td, struct reg *regs)
+{
+	struct trapframe *tp;
+	register_t rflags;
+
+	tp = td->td_frame;
+	rflags = regs->r_rflags & 0xffffffff;
+	if (!EFL_SECURE(rflags, tp->tf_rflags) || !CS_SECURE(regs->r_cs))
+		return (EINVAL);
+	tp->tf_r15 = regs->r_r15;
+	tp->tf_r14 = regs->r_r14;
+	tp->tf_r13 = regs->r_r13;
+	tp->tf_r12 = regs->r_r12;
+	tp->tf_r11 = regs->r_r11;
+	tp->tf_r10 = regs->r_r10;
+	tp->tf_r9  = regs->r_r9;
+	tp->tf_r8  = regs->r_r8;
+	tp->tf_rdi = regs->r_rdi;
+	tp->tf_rsi = regs->r_rsi;
+	tp->tf_rbp = regs->r_rbp;
+	tp->tf_rbx = regs->r_rbx;
+	tp->tf_rdx = regs->r_rdx;
+	tp->tf_rcx = regs->r_rcx;
+	tp->tf_rax = regs->r_rax;
+	tp->tf_rip = regs->r_rip;
+	tp->tf_cs = regs->r_cs;
+	tp->tf_rflags = rflags;
+	tp->tf_rsp = regs->r_rsp;
+	tp->tf_ss = regs->r_ss;
+	if (0) {	/* XXXKIB */
+		tp->tf_ds = regs->r_ds;
+		tp->tf_es = regs->r_es;
+		tp->tf_fs = regs->r_fs;
+		tp->tf_gs = regs->r_gs;
+		tp->tf_flags = TF_HASSEGS;
+	}
+	set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
+	return (0);
+}
+
+/* XXX check all this stuff! */
+/* externalize from sv_xmm */
+static void
+fill_fpregs_xmm(struct savefpu *sv_xmm, struct fpreg *fpregs)
+{
+	struct envxmm *penv_fpreg = (struct envxmm *)&fpregs->fpr_env;
+	struct envxmm *penv_xmm = &sv_xmm->sv_env;
+	int i;
+
+	/* pcb -> fpregs */
+	bzero(fpregs, sizeof(*fpregs));
+
+	/* FPU control/status */
+	penv_fpreg->en_cw = penv_xmm->en_cw;
+	penv_fpreg->en_sw = penv_xmm->en_sw;
+	penv_fpreg->en_tw = penv_xmm->en_tw;
+	penv_fpreg->en_opcode = penv_xmm->en_opcode;
+	penv_fpreg->en_rip = penv_xmm->en_rip;
+	penv_fpreg->en_rdp = penv_xmm->en_rdp;
+	penv_fpreg->en_mxcsr = penv_xmm->en_mxcsr;
+	penv_fpreg->en_mxcsr_mask = penv_xmm->en_mxcsr_mask;
+
+	/* FPU registers */
+	for (i = 0; i < 8; ++i)
+		bcopy(sv_xmm->sv_fp[i].fp_acc.fp_bytes, fpregs->fpr_acc[i], 10);
+
+	/* SSE registers */
+	for (i = 0; i < 16; ++i)
+		bcopy(sv_xmm->sv_xmm[i].xmm_bytes, fpregs->fpr_xacc[i], 16);
+}
+
+/* internalize from fpregs into sv_xmm */
+static void
+set_fpregs_xmm(struct fpreg *fpregs, struct savefpu *sv_xmm)
+{
+	struct envxmm *penv_xmm = &sv_xmm->sv_env;
+	struct envxmm *penv_fpreg = (struct envxmm *)&fpregs->fpr_env;
+	int i;
+
+	/* fpregs -> pcb */
+	/* FPU control/status */
+	penv_xmm->en_cw = penv_fpreg->en_cw;
+	penv_xmm->en_sw = penv_fpreg->en_sw;
+	penv_xmm->en_tw = penv_fpreg->en_tw;
+	penv_xmm->en_opcode = penv_fpreg->en_opcode;
+	penv_xmm->en_rip = penv_fpreg->en_rip;
+	penv_xmm->en_rdp = penv_fpreg->en_rdp;
+	penv_xmm->en_mxcsr = penv_fpreg->en_mxcsr;
+	penv_xmm->en_mxcsr_mask = penv_fpreg->en_mxcsr_mask & cpu_mxcsr_mask;
+
+	/* FPU registers */
+	for (i = 0; i < 8; ++i)
+		bcopy(fpregs->fpr_acc[i], sv_xmm->sv_fp[i].fp_acc.fp_bytes, 10);
+
+	/* SSE registers */
+	for (i = 0; i < 16; ++i)
+		bcopy(fpregs->fpr_xacc[i], sv_xmm->sv_xmm[i].xmm_bytes, 16);
+}
+
+/* externalize from td->pcb */
+int
+fill_fpregs(struct thread *td, struct fpreg *fpregs)
+{
+
+	KASSERT(td == curthread || TD_IS_SUSPENDED(td) ||
+	    P_SHOULDSTOP(td->td_proc),
+	    ("not suspended thread %p", td));
+	fpugetregs(td);
+	fill_fpregs_xmm(get_pcb_user_save_td(td), fpregs);
+	return (0);
+}
+
+/* internalize to td->pcb */
+int
+set_fpregs(struct thread *td, struct fpreg *fpregs)
+{
+
+	critical_enter();
+	set_fpregs_xmm(fpregs, get_pcb_user_save_td(td));
+	fpuuserinited(td);
+	critical_exit();
+	return (0);
+}
+
+/*
+ * Get machine context.
+ */
+int
+get_mcontext(struct thread *td, mcontext_t *mcp, int flags)
+{
+	struct pcb *pcb;
+	struct trapframe *tp;
+
+	pcb = td->td_pcb;
+	tp = td->td_frame;
+	PROC_LOCK(curthread->td_proc);
+	mcp->mc_onstack = sigonstack(tp->tf_rsp);
+	PROC_UNLOCK(curthread->td_proc);
+	mcp->mc_r15 = tp->tf_r15;
+	mcp->mc_r14 = tp->tf_r14;
+	mcp->mc_r13 = tp->tf_r13;
+	mcp->mc_r12 = tp->tf_r12;
+	mcp->mc_r11 = tp->tf_r11;
+	mcp->mc_r10 = tp->tf_r10;
+	mcp->mc_r9  = tp->tf_r9;
+	mcp->mc_r8  = tp->tf_r8;
+	mcp->mc_rdi = tp->tf_rdi;
+	mcp->mc_rsi = tp->tf_rsi;
+	mcp->mc_rbp = tp->tf_rbp;
+	mcp->mc_rbx = tp->tf_rbx;
+	mcp->mc_rcx = tp->tf_rcx;
+	mcp->mc_rflags = tp->tf_rflags;
+	if (flags & GET_MC_CLEAR_RET) {
+		mcp->mc_rax = 0;
+		mcp->mc_rdx = 0;
+		mcp->mc_rflags &= ~PSL_C;
+	} else {
+		mcp->mc_rax = tp->tf_rax;
+		mcp->mc_rdx = tp->tf_rdx;
+	}
+	mcp->mc_rip = tp->tf_rip;
+	mcp->mc_cs = tp->tf_cs;
+	mcp->mc_rsp = tp->tf_rsp;
+	mcp->mc_ss = tp->tf_ss;
+	mcp->mc_ds = tp->tf_ds;
+	mcp->mc_es = tp->tf_es;
+	mcp->mc_fs = tp->tf_fs;
+	mcp->mc_gs = tp->tf_gs;
+	mcp->mc_flags = tp->tf_flags;
+	mcp->mc_len = sizeof(*mcp);
+	get_fpcontext(td, mcp, NULL, 0);
+	update_pcb_bases(pcb);
+	mcp->mc_fsbase = pcb->pcb_fsbase;
+	mcp->mc_gsbase = pcb->pcb_gsbase;
+	mcp->mc_xfpustate = 0;
+	mcp->mc_xfpustate_len = 0;
+	bzero(mcp->mc_spare, sizeof(mcp->mc_spare));
+	return (0);
+}
+
+/*
+ * Set machine context.
+ *
+ * However, we don't set any but the user modifiable flags, and we won't
+ * touch the cs selector.
+ */
+int
+set_mcontext(struct thread *td, mcontext_t *mcp)
+{
+	struct pcb *pcb;
+	struct trapframe *tp;
+	char *xfpustate;
+	long rflags;
+	int ret;
+
+	pcb = td->td_pcb;
+	tp = td->td_frame;
+	if (mcp->mc_len != sizeof(*mcp) ||
+	    (mcp->mc_flags & ~_MC_FLAG_MASK) != 0)
+		return (EINVAL);
+	rflags = (mcp->mc_rflags & PSL_USERCHANGE) |
+	    (tp->tf_rflags & ~PSL_USERCHANGE);
+	if (mcp->mc_flags & _MC_HASFPXSTATE) {
+		if (mcp->mc_xfpustate_len > cpu_max_ext_state_size -
+		    sizeof(struct savefpu))
+			return (EINVAL);
+		xfpustate = __builtin_alloca(mcp->mc_xfpustate_len);
+		ret = copyin((void *)mcp->mc_xfpustate, xfpustate,
+		    mcp->mc_xfpustate_len);
+		if (ret != 0)
+			return (ret);
+	} else
+		xfpustate = NULL;
+	ret = set_fpcontext(td, mcp, xfpustate, mcp->mc_xfpustate_len);
+	if (ret != 0)
+		return (ret);
+	tp->tf_r15 = mcp->mc_r15;
+	tp->tf_r14 = mcp->mc_r14;
+	tp->tf_r13 = mcp->mc_r13;
+	tp->tf_r12 = mcp->mc_r12;
+	tp->tf_r11 = mcp->mc_r11;
+	tp->tf_r10 = mcp->mc_r10;
+	tp->tf_r9  = mcp->mc_r9;
+	tp->tf_r8  = mcp->mc_r8;
+	tp->tf_rdi = mcp->mc_rdi;
+	tp->tf_rsi = mcp->mc_rsi;
+	tp->tf_rbp = mcp->mc_rbp;
+	tp->tf_rbx = mcp->mc_rbx;
+	tp->tf_rdx = mcp->mc_rdx;
+	tp->tf_rcx = mcp->mc_rcx;
+	tp->tf_rax = mcp->mc_rax;
+	tp->tf_rip = mcp->mc_rip;
+	tp->tf_rflags = rflags;
+	tp->tf_rsp = mcp->mc_rsp;
+	tp->tf_ss = mcp->mc_ss;
+	tp->tf_flags = mcp->mc_flags;
+	if (tp->tf_flags & TF_HASSEGS) {
+		tp->tf_ds = mcp->mc_ds;
+		tp->tf_es = mcp->mc_es;
+		tp->tf_fs = mcp->mc_fs;
+		tp->tf_gs = mcp->mc_gs;
+	}
+	set_pcb_flags(pcb, PCB_FULL_IRET);
+	if (mcp->mc_flags & _MC_HASBASES) {
+		pcb->pcb_fsbase = mcp->mc_fsbase;
+		pcb->pcb_gsbase = mcp->mc_gsbase;
+	}
+	return (0);
+}
+
+static void
+get_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpusave,
+    size_t xfpusave_len)
+{
+	size_t max_len, len;
+
+	mcp->mc_ownedfp = fpugetregs(td);
+	bcopy(get_pcb_user_save_td(td), &mcp->mc_fpstate[0],
+	    sizeof(mcp->mc_fpstate));
+	mcp->mc_fpformat = fpuformat();
+	if (!use_xsave || xfpusave_len == 0)
+		return;
+	max_len = cpu_max_ext_state_size - sizeof(struct savefpu);
+	len = xfpusave_len;
+	if (len > max_len) {
+		len = max_len;
+		bzero(xfpusave + max_len, len - max_len);
+	}
+	mcp->mc_flags |= _MC_HASFPXSTATE;
+	mcp->mc_xfpustate_len = len;
+	bcopy(get_pcb_user_save_td(td) + 1, xfpusave, len);
+}
+
+static int
+set_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpustate,
+    size_t xfpustate_len)
+{
+	int error;
+
+	if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
+		return (0);
+	else if (mcp->mc_fpformat != _MC_FPFMT_XMM)
+		return (EINVAL);
+	else if (mcp->mc_ownedfp == _MC_FPOWNED_NONE) {
+		/* We don't care what state is left in the FPU or PCB. */
+		fpstate_drop(td);
+		error = 0;
+	} else if (mcp->mc_ownedfp == _MC_FPOWNED_FPU ||
+	    mcp->mc_ownedfp == _MC_FPOWNED_PCB) {
+		error = fpusetregs(td, (struct savefpu *)&mcp->mc_fpstate,
+		    xfpustate, xfpustate_len);
+	} else
+		return (EINVAL);
+	return (error);
+}
+
+void
+fpstate_drop(struct thread *td)
+{
+
+	KASSERT(PCB_USER_FPU(td->td_pcb), ("fpstate_drop: kernel-owned fpu"));
+	critical_enter();
+	if (PCPU_GET(fpcurthread) == td)
+		fpudrop();
+	/*
+	 * XXX force a full drop of the fpu.  The above only drops it if we
+	 * owned it.
+	 *
+	 * XXX I don't much like fpugetuserregs()'s semantics of doing a full
+	 * drop.  Dropping only to the pcb matches fnsave's behaviour.
+	 * We only need to drop to !PCB_INITDONE in sendsig().  But
+	 * sendsig() is the only caller of fpugetuserregs()... perhaps we just
+	 * have too many layers.
+	 */
+	clear_pcb_flags(curthread->td_pcb,
+	    PCB_FPUINITDONE | PCB_USERFPUINITDONE);
+	critical_exit();
+}
+
+int
+fill_dbregs(struct thread *td, struct dbreg *dbregs)
+{
+	struct pcb *pcb;
+
+	if (td == NULL) {
+		dbregs->dr[0] = rdr0();
+		dbregs->dr[1] = rdr1();
+		dbregs->dr[2] = rdr2();
+		dbregs->dr[3] = rdr3();
+		dbregs->dr[6] = rdr6();
+		dbregs->dr[7] = rdr7();
+	} else {
+		pcb = td->td_pcb;
+		dbregs->dr[0] = pcb->pcb_dr0;
+		dbregs->dr[1] = pcb->pcb_dr1;
+		dbregs->dr[2] = pcb->pcb_dr2;
+		dbregs->dr[3] = pcb->pcb_dr3;
+		dbregs->dr[6] = pcb->pcb_dr6;
+		dbregs->dr[7] = pcb->pcb_dr7;
+	}
+	dbregs->dr[4] = 0;
+	dbregs->dr[5] = 0;
+	dbregs->dr[8] = 0;
+	dbregs->dr[9] = 0;
+	dbregs->dr[10] = 0;
+	dbregs->dr[11] = 0;
+	dbregs->dr[12] = 0;
+	dbregs->dr[13] = 0;
+	dbregs->dr[14] = 0;
+	dbregs->dr[15] = 0;
+	return (0);
+}
+
+int
+set_dbregs(struct thread *td, struct dbreg *dbregs)
+{
+	struct pcb *pcb;
+	int i;
+
+	if (td == NULL) {
+		load_dr0(dbregs->dr[0]);
+		load_dr1(dbregs->dr[1]);
+		load_dr2(dbregs->dr[2]);
+		load_dr3(dbregs->dr[3]);
+		load_dr6(dbregs->dr[6]);
+		load_dr7(dbregs->dr[7]);
+	} else {
+		/*
+		 * Don't let an illegal value for dr7 get set.  Specifically,
+		 * check for undefined settings.  Setting these bit patterns
+		 * result in undefined behaviour and can lead to an unexpected
+		 * TRCTRAP or a general protection fault right here.
+		 * Upper bits of dr6 and dr7 must not be set
+		 */
+		for (i = 0; i < 4; i++) {
+			if (DBREG_DR7_ACCESS(dbregs->dr[7], i) == 0x02)
+				return (EINVAL);
+			if (td->td_frame->tf_cs == _ucode32sel &&
+			    DBREG_DR7_LEN(dbregs->dr[7], i) == DBREG_DR7_LEN_8)
+				return (EINVAL);
+		}
+		if ((dbregs->dr[6] & 0xffffffff00000000ul) != 0 ||
+		    (dbregs->dr[7] & 0xffffffff00000000ul) != 0)
+			return (EINVAL);
+
+		pcb = td->td_pcb;
+
+		/*
+		 * Don't let a process set a breakpoint that is not within the
+		 * process's address space.  If a process could do this, it
+		 * could halt the system by setting a breakpoint in the kernel
+		 * (if ddb was enabled).  Thus, we need to check to make sure
+		 * that no breakpoints are being enabled for addresses outside
+		 * process's address space.
+		 *
+		 * XXX - what about when the watched area of the user's
+		 * address space is written into from within the kernel
+		 * ... wouldn't that still cause a breakpoint to be generated
+		 * from within kernel mode?
+		 */
+
+		if (DBREG_DR7_ENABLED(dbregs->dr[7], 0)) {
+			/* dr0 is enabled */
+			if (dbregs->dr[0] >= VM_MAXUSER_ADDRESS)
+				return (EINVAL);
+		}
+		if (DBREG_DR7_ENABLED(dbregs->dr[7], 1)) {
+			/* dr1 is enabled */
+			if (dbregs->dr[1] >= VM_MAXUSER_ADDRESS)
+				return (EINVAL);
+		}
+		if (DBREG_DR7_ENABLED(dbregs->dr[7], 2)) {
+			/* dr2 is enabled */
+			if (dbregs->dr[2] >= VM_MAXUSER_ADDRESS)
+				return (EINVAL);
+		}
+		if (DBREG_DR7_ENABLED(dbregs->dr[7], 3)) {
+			/* dr3 is enabled */
+			if (dbregs->dr[3] >= VM_MAXUSER_ADDRESS)
+				return (EINVAL);
+		}
+
+		pcb->pcb_dr0 = dbregs->dr[0];
+		pcb->pcb_dr1 = dbregs->dr[1];
+		pcb->pcb_dr2 = dbregs->dr[2];
+		pcb->pcb_dr3 = dbregs->dr[3];
+		pcb->pcb_dr6 = dbregs->dr[6];
+		pcb->pcb_dr7 = dbregs->dr[7];
+
+		set_pcb_flags(pcb, PCB_DBREGS);
+	}
+
+	return (0);
+}
+
+void
+reset_dbregs(void)
+{
+
+	load_dr7(0);	/* Turn off the control bits first */
+	load_dr0(0);
+	load_dr1(0);
+	load_dr2(0);
+	load_dr3(0);
+	load_dr6(0);
+}
+
+/*
+ * Return > 0 if a hardware breakpoint has been hit, and the
+ * breakpoint was in user space.  Return 0, otherwise.
+ */
+int
+user_dbreg_trap(register_t dr6)
+{
+        u_int64_t dr7;
+        u_int64_t bp;       /* breakpoint bits extracted from dr6 */
+        int nbp;            /* number of breakpoints that triggered */
+        caddr_t addr[4];    /* breakpoint addresses */
+        int i;
+
+        bp = dr6 & DBREG_DR6_BMASK;
+        if (bp == 0) {
+                /*
+                 * None of the breakpoint bits are set meaning this
+                 * trap was not caused by any of the debug registers
+                 */
+                return 0;
+        }
+
+        dr7 = rdr7();
+        if ((dr7 & 0x000000ff) == 0) {
+                /*
+                 * all GE and LE bits in the dr7 register are zero,
+                 * thus the trap couldn't have been caused by the
+                 * hardware debug registers
+                 */
+                return 0;
+        }
+
+        nbp = 0;
+
+        /*
+         * at least one of the breakpoints were hit, check to see
+         * which ones and if any of them are user space addresses
+         */
+
+        if (bp & 0x01) {
+                addr[nbp++] = (caddr_t)rdr0();
+        }
+        if (bp & 0x02) {
+                addr[nbp++] = (caddr_t)rdr1();
+        }
+        if (bp & 0x04) {
+                addr[nbp++] = (caddr_t)rdr2();
+        }
+        if (bp & 0x08) {
+                addr[nbp++] = (caddr_t)rdr3();
+        }
+
+        for (i = 0; i < nbp; i++) {
+                if (addr[i] < (caddr_t)VM_MAXUSER_ADDRESS) {
+                        /*
+                         * addr[i] is in user space
+                         */
+                        return nbp;
+                }
+        }
+
+        /*
+         * None of the breakpoints are in user space.
+         */
+        return 0;
+}
diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index 55d52a28b576..d4e2356a9ae1 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -167,10 +167,6 @@ CTASSERT(PC_PTI_STACK_SZ * sizeof(register_t) >= 2 * sizeof(struct pti_frame) -
 extern u_int64_t hammer_time(u_int64_t, u_int64_t);
 
 static void cpu_startup(void *);
-static void get_fpcontext(struct thread *td, mcontext_t *mcp,
-    char *xfpusave, size_t xfpusave_len);
-static int  set_fpcontext(struct thread *td, mcontext_t *mcp,
-    char *xfpustate, size_t xfpustate_len);
 SYSINIT(cpu, SI_SUB_CPU, SI_ORDER_FIRST, cpu_startup, NULL);
 
 /* Preload data parse function */
@@ -322,331 +318,6 @@ late_ifunc_resolve(void *dummy __unused)
 }
 SYSINIT(late_ifunc_resolve, SI_SUB_CPU, SI_ORDER_ANY, late_ifunc_resolve, NULL);
 
-/*
- * Send an interrupt to process.
- *
- * Stack is set up to allow sigcode stored
- * at top to call routine, followed by call
- * to sigreturn routine below.  After sigreturn
- * resets the signal mask, the stack, and the
- * frame pointer, it returns to the user
- * specified pc, psl.
- */
-void
-sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
-{
-	struct sigframe sf, *sfp;
-	struct pcb *pcb;
-	struct proc *p;
-	struct thread *td;
-	struct sigacts *psp;
-	char *sp;
-	struct trapframe *regs;
-	char *xfpusave;
-	size_t xfpusave_len;
-	int sig;
-	int oonstack;
-
-	td = curthread;
-	pcb = td->td_pcb;
-	p = td->td_proc;
-	PROC_LOCK_ASSERT(p, MA_OWNED);
-	sig = ksi->ksi_signo;
-	psp = p->p_sigacts;
-	mtx_assert(&psp->ps_mtx, MA_OWNED);
-	regs = td->td_frame;
-	oonstack = sigonstack(regs->tf_rsp);
-
-	if (cpu_max_ext_state_size > sizeof(struct savefpu) && use_xsave) {
-		xfpusave_len = cpu_max_ext_state_size - sizeof(struct savefpu);
-		xfpusave = __builtin_alloca(xfpusave_len);
-	} else {
-		xfpusave_len = 0;
-		xfpusave = NULL;
-	}
-
-	/* Save user context. */
-	bzero(&sf, sizeof(sf));
-	sf.sf_uc.uc_sigmask = *mask;
-	sf.sf_uc.uc_stack = td->td_sigstk;
-	sf.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
-	    ? ((oonstack) ? SS_ONSTACK : 0) : SS_DISABLE;
-	sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
-	bcopy(regs, &sf.sf_uc.uc_mcontext.mc_rdi, sizeof(*regs));
-	sf.sf_uc.uc_mcontext.mc_len = sizeof(sf.sf_uc.uc_mcontext); /* magic */
-	get_fpcontext(td, &sf.sf_uc.uc_mcontext, xfpusave, xfpusave_len);
-	fpstate_drop(td);
-	update_pcb_bases(pcb);
-	sf.sf_uc.uc_mcontext.mc_fsbase = pcb->pcb_fsbase;
-	sf.sf_uc.uc_mcontext.mc_gsbase = pcb->pcb_gsbase;
-	bzero(sf.sf_uc.uc_mcontext.mc_spare,
-	    sizeof(sf.sf_uc.uc_mcontext.mc_spare));
-
-	/* Allocate space for the signal handler context. */
-	if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
-	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
-		sp = (char *)td->td_sigstk.ss_sp + td->td_sigstk.ss_size;
-#if defined(COMPAT_43)
-		td->td_sigstk.ss_flags |= SS_ONSTACK;
-#endif
-	} else
-		sp = (char *)regs->tf_rsp - 128;
-	if (xfpusave != NULL) {
-		sp -= xfpusave_len;
-		sp = (char *)((unsigned long)sp & ~0x3Ful);
-		sf.sf_uc.uc_mcontext.mc_xfpustate = (register_t)sp;
-	}
-	sp -= sizeof(struct sigframe);
-	/* Align to 16 bytes. */
-	sfp = (struct sigframe *)((unsigned long)sp & ~0xFul);
-
-	/* Build the argument list for the signal handler. */
-	regs->tf_rdi = sig;			/* arg 1 in %rdi */
-	regs->tf_rdx = (register_t)&sfp->sf_uc;	/* arg 3 in %rdx */
-	bzero(&sf.sf_si, sizeof(sf.sf_si));
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
-		/* Signal handler installed with SA_SIGINFO. */
-		regs->tf_rsi = (register_t)&sfp->sf_si;	/* arg 2 in %rsi */
-		sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;
-
-		/* Fill in POSIX parts */
-		sf.sf_si = ksi->ksi_info;
-		sf.sf_si.si_signo = sig; /* maybe a translated signal */
-		regs->tf_rcx = (register_t)ksi->ksi_addr; /* arg 4 in %rcx */
-	} else {
-		/* Old FreeBSD-style arguments. */
-		regs->tf_rsi = ksi->ksi_code;	/* arg 2 in %rsi */
-		regs->tf_rcx = (register_t)ksi->ksi_addr; /* arg 4 in %rcx */
-		sf.sf_ahu.sf_handler = catcher;
-	}
-	mtx_unlock(&psp->ps_mtx);
-	PROC_UNLOCK(p);
-
-	/*
-	 * Copy the sigframe out to the user's stack.
-	 */
-	if (copyout(&sf, sfp, sizeof(*sfp)) != 0 ||
-	    (xfpusave != NULL && copyout(xfpusave,
-	    (void *)sf.sf_uc.uc_mcontext.mc_xfpustate, xfpusave_len)
-	    != 0)) {
-#ifdef DEBUG
-		printf("process %ld has trashed its stack\n", (long)p->p_pid);
-#endif
-		PROC_LOCK(p);
-		sigexit(td, SIGILL);
-	}
-
-	regs->tf_rsp = (long)sfp;
-	regs->tf_rip = p->p_sysent->sv_sigcode_base;
-	regs->tf_rflags &= ~(PSL_T | PSL_D);
-	regs->tf_cs = _ucodesel;
-	regs->tf_ds = _udatasel;
-	regs->tf_ss = _udatasel;
-	regs->tf_es = _udatasel;
-	regs->tf_fs = _ufssel;
-	regs->tf_gs = _ugssel;
-	regs->tf_flags = TF_HASSEGS;
-	PROC_LOCK(p);
-	mtx_lock(&psp->ps_mtx);
-}
-
-/*
- * System call to cleanup state after a signal
- * has been taken.  Reset signal mask and
- * stack state from context left by sendsig (above).
- * Return to previous pc and psl as specified by
- * context left by sendsig. Check carefully to
- * make sure that the user has not modified the
- * state to gain improper privileges.
- *
- * MPSAFE
- */
-int
-sys_sigreturn(td, uap)
-	struct thread *td;
-	struct sigreturn_args /* {
-		const struct __ucontext *sigcntxp;
-	} */ *uap;
-{
-	ucontext_t uc;
-	struct pcb *pcb;
-	struct proc *p;
-	struct trapframe *regs;
-	ucontext_t *ucp;
-	char *xfpustate;
-	size_t xfpustate_len;
-	long rflags;
-	int cs, error, ret;
-	ksiginfo_t ksi;
-
-	pcb = td->td_pcb;
-	p = td->td_proc;
-
-	error = copyin(uap->sigcntxp, &uc, sizeof(uc));
-	if (error != 0) {
-		uprintf("pid %d (%s): sigreturn copyin failed\n",
-		    p->p_pid, td->td_name);
-		return (error);
-	}
-	ucp = &uc;
-	if ((ucp->uc_mcontext.mc_flags & ~_MC_FLAG_MASK) != 0) {
-		uprintf("pid %d (%s): sigreturn mc_flags %x\n", p->p_pid,
-		    td->td_name, ucp->uc_mcontext.mc_flags);
-		return (EINVAL);
-	}
-	regs = td->td_frame;
-	rflags = ucp->uc_mcontext.mc_rflags;
-	/*
-	 * Don't allow users to change privileged or reserved flags.
-	 */
-	if (!EFL_SECURE(rflags, regs->tf_rflags)) {
-		uprintf("pid %d (%s): sigreturn rflags = 0x%lx\n", p->p_pid,
-		    td->td_name, rflags);
-		return (EINVAL);
-	}
-
-	/*
-	 * Don't allow users to load a valid privileged %cs.  Let the
-	 * hardware check for invalid selectors, excess privilege in
-	 * other selectors, invalid %eip's and invalid %esp's.
-	 */
-	cs = ucp->uc_mcontext.mc_cs;
-	if (!CS_SECURE(cs)) {
-		uprintf("pid %d (%s): sigreturn cs = 0x%x\n", p->p_pid,
-		    td->td_name, cs);
-		ksiginfo_init_trap(&ksi);
-		ksi.ksi_signo = SIGBUS;
-		ksi.ksi_code = BUS_OBJERR;
-		ksi.ksi_trapno = T_PROTFLT;
-		ksi.ksi_addr = (void *)regs->tf_rip;
-		trapsignal(td, &ksi);
-		return (EINVAL);
-	}
-
-	if ((uc.uc_mcontext.mc_flags & _MC_HASFPXSTATE) != 0) {
-		xfpustate_len = uc.uc_mcontext.mc_xfpustate_len;
-		if (xfpustate_len > cpu_max_ext_state_size -
-		    sizeof(struct savefpu)) {
-			uprintf("pid %d (%s): sigreturn xfpusave_len = 0x%zx\n",
-			    p->p_pid, td->td_name, xfpustate_len);
-			return (EINVAL);
-		}
-		xfpustate = __builtin_alloca(xfpustate_len);
-		error = copyin((const void *)uc.uc_mcontext.mc_xfpustate,
-		    xfpustate, xfpustate_len);
-		if (error != 0) {
-			uprintf(
-	"pid %d (%s): sigreturn copying xfpustate failed\n",
-			    p->p_pid, td->td_name);
-			return (error);
-		}
-	} else {
-		xfpustate = NULL;
-		xfpustate_len = 0;
-	}
-	ret = set_fpcontext(td, &ucp->uc_mcontext, xfpustate, xfpustate_len);
-	if (ret != 0) {
-		uprintf("pid %d (%s): sigreturn set_fpcontext err %d\n",
-		    p->p_pid, td->td_name, ret);
-		return (ret);
-	}
-	bcopy(&ucp->uc_mcontext.mc_rdi, regs, sizeof(*regs));
-	update_pcb_bases(pcb);
-	pcb->pcb_fsbase = ucp->uc_mcontext.mc_fsbase;
-	pcb->pcb_gsbase = ucp->uc_mcontext.mc_gsbase;
-
-#if defined(COMPAT_43)
-	if (ucp->uc_mcontext.mc_onstack & 1)
-		td->td_sigstk.ss_flags |= SS_ONSTACK;
-	else
-		td->td_sigstk.ss_flags &= ~SS_ONSTACK;
-#endif
-
-	kern_sigprocmask(td, SIG_SETMASK, &ucp->uc_sigmask, NULL, 0);
-	return (EJUSTRETURN);
-}
-
-#ifdef COMPAT_FREEBSD4
-int
-freebsd4_sigreturn(struct thread *td, struct freebsd4_sigreturn_args *uap)
-{
-
-	return sys_sigreturn(td, (struct sigreturn_args *)uap);
-}
-#endif
-
-/*
- * Reset the hardware debug registers if they were in use.
- * They won't have any meaning for the newly exec'd process.
- */
-void
-x86_clear_dbregs(struct pcb *pcb)
-{
-	if ((pcb->pcb_flags & PCB_DBREGS) == 0)
-		return;
-
-	pcb->pcb_dr0 = 0;
-	pcb->pcb_dr1 = 0;
-	pcb->pcb_dr2 = 0;
-	pcb->pcb_dr3 = 0;
-	pcb->pcb_dr6 = 0;
-	pcb->pcb_dr7 = 0;
-
-	if (pcb == curpcb) {
-		/*
-		 * Clear the debug registers on the running CPU,
-		 * otherwise they will end up affecting the next
-		 * process we switch to.
-		 */
-		reset_dbregs();
-	}
-	clear_pcb_flags(pcb, PCB_DBREGS);
-}
-
-/*
- * Reset registers to default values on exec.
- */
-void
-exec_setregs(struct thread *td, struct image_params *imgp, uintptr_t stack)
-{
-	struct trapframe *regs;
-	struct pcb *pcb;
-	register_t saved_rflags;
-
-	regs = td->td_frame;
-	pcb = td->td_pcb;
-
-	if (td->td_proc->p_md.md_ldt != NULL)
-		user_ldt_free(td);
-
-	update_pcb_bases(pcb);
-	pcb->pcb_fsbase = 0;
-	pcb->pcb_gsbase = 0;
-	clear_pcb_flags(pcb, PCB_32BIT);
-	pcb->pcb_initial_fpucw = __INITIAL_FPUCW__;
-
-	saved_rflags = regs->tf_rflags & PSL_T;
-	bzero((char *)regs, sizeof(struct trapframe));
-	regs->tf_rip = imgp->entry_addr;
-	regs->tf_rsp = ((stack - 8) & ~0xFul) + 8;
-	regs->tf_rdi = stack;		/* argv */
-	regs->tf_rflags = PSL_USER | saved_rflags;
-	regs->tf_ss = _udatasel;
-	regs->tf_cs = _ucodesel;
-	regs->tf_ds = _udatasel;
-	regs->tf_es = _udatasel;
-	regs->tf_fs = _ufssel;
-	regs->tf_gs = _ugssel;
-	regs->tf_flags = TF_HASSEGS;
-
-	x86_clear_dbregs(pcb);
-
-	/*
-	 * Drop the FP state if we hold it, so that the process gets a
-	 * clean FP state if it uses the FPU again.
-	 */
-	fpstate_drop(td);
-}
 
 void
 cpu_setregs(void)
@@ -2068,601 +1739,6 @@ makectx(struct trapframe *tf, struct pcb *pcb)
 	pcb->pcb_rsp = tf->tf_rsp;
 }
 
-int
-ptrace_set_pc(struct thread *td, unsigned long addr)
-{
-
-	td->td_frame->tf_rip = addr;
-	set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
-	return (0);
-}
-
-int
-ptrace_single_step(struct thread *td)
-{
-
-	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
-	if ((td->td_frame->tf_rflags & PSL_T) == 0) {
-		td->td_frame->tf_rflags |= PSL_T;
-		td->td_dbgflags |= TDB_STEP;
-	}
-	return (0);
-}
-
-int
-ptrace_clear_single_step(struct thread *td)
-{
-
-	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
-	td->td_frame->tf_rflags &= ~PSL_T;
-	td->td_dbgflags &= ~TDB_STEP;
-	return (0);
-}
-
-int
-fill_regs(struct thread *td, struct reg *regs)
-{
-	struct trapframe *tp;
-
-	tp = td->td_frame;
-	return (fill_frame_regs(tp, regs));
-}
-
-int
-fill_frame_regs(struct trapframe *tp, struct reg *regs)
-{
-
-	regs->r_r15 = tp->tf_r15;
-	regs->r_r14 = tp->tf_r14;
-	regs->r_r13 = tp->tf_r13;
-	regs->r_r12 = tp->tf_r12;
-	regs->r_r11 = tp->tf_r11;
-	regs->r_r10 = tp->tf_r10;
-	regs->r_r9  = tp->tf_r9;
-	regs->r_r8  = tp->tf_r8;
-	regs->r_rdi = tp->tf_rdi;
-	regs->r_rsi = tp->tf_rsi;
-	regs->r_rbp = tp->tf_rbp;
-	regs->r_rbx = tp->tf_rbx;
-	regs->r_rdx = tp->tf_rdx;
-	regs->r_rcx = tp->tf_rcx;
-	regs->r_rax = tp->tf_rax;
-	regs->r_rip = tp->tf_rip;
-	regs->r_cs = tp->tf_cs;
-	regs->r_rflags = tp->tf_rflags;
-	regs->r_rsp = tp->tf_rsp;
-	regs->r_ss = tp->tf_ss;
-	if (tp->tf_flags & TF_HASSEGS) {
-		regs->r_ds = tp->tf_ds;
-		regs->r_es = tp->tf_es;
-		regs->r_fs = tp->tf_fs;
-		regs->r_gs = tp->tf_gs;
-	} else {
-		regs->r_ds = 0;
-		regs->r_es = 0;
-		regs->r_fs = 0;
-		regs->r_gs = 0;
-	}
-	regs->r_err = 0;
-	regs->r_trapno = 0;
-	return (0);
-}
-
-int
-set_regs(struct thread *td, struct reg *regs)
-{
-	struct trapframe *tp;
-	register_t rflags;
-
-	tp = td->td_frame;
-	rflags = regs->r_rflags & 0xffffffff;
-	if (!EFL_SECURE(rflags, tp->tf_rflags) || !CS_SECURE(regs->r_cs))
-		return (EINVAL);
-	tp->tf_r15 = regs->r_r15;
-	tp->tf_r14 = regs->r_r14;
-	tp->tf_r13 = regs->r_r13;
-	tp->tf_r12 = regs->r_r12;
-	tp->tf_r11 = regs->r_r11;
-	tp->tf_r10 = regs->r_r10;
-	tp->tf_r9  = regs->r_r9;
-	tp->tf_r8  = regs->r_r8;
-	tp->tf_rdi = regs->r_rdi;
-	tp->tf_rsi = regs->r_rsi;
-	tp->tf_rbp = regs->r_rbp;
-	tp->tf_rbx = regs->r_rbx;
-	tp->tf_rdx = regs->r_rdx;
-	tp->tf_rcx = regs->r_rcx;
-	tp->tf_rax = regs->r_rax;
-	tp->tf_rip = regs->r_rip;
-	tp->tf_cs = regs->r_cs;
-	tp->tf_rflags = rflags;
-	tp->tf_rsp = regs->r_rsp;
-	tp->tf_ss = regs->r_ss;
-	if (0) {	/* XXXKIB */
-		tp->tf_ds = regs->r_ds;
-		tp->tf_es = regs->r_es;
-		tp->tf_fs = regs->r_fs;
-		tp->tf_gs = regs->r_gs;
-		tp->tf_flags = TF_HASSEGS;
-	}
-	set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
-	return (0);
-}
-
-/* XXX check all this stuff! */
-/* externalize from sv_xmm */
-static void
-fill_fpregs_xmm(struct savefpu *sv_xmm, struct fpreg *fpregs)
-{
-	struct envxmm *penv_fpreg = (struct envxmm *)&fpregs->fpr_env;
-	struct envxmm *penv_xmm = &sv_xmm->sv_env;
-	int i;
-
-	/* pcb -> fpregs */
-	bzero(fpregs, sizeof(*fpregs));
-
-	/* FPU control/status */
-	penv_fpreg->en_cw = penv_xmm->en_cw;
-	penv_fpreg->en_sw = penv_xmm->en_sw;
-	penv_fpreg->en_tw = penv_xmm->en_tw;
-	penv_fpreg->en_opcode = penv_xmm->en_opcode;
-	penv_fpreg->en_rip = penv_xmm->en_rip;
-	penv_fpreg->en_rdp = penv_xmm->en_rdp;
-	penv_fpreg->en_mxcsr = penv_xmm->en_mxcsr;
-	penv_fpreg->en_mxcsr_mask = penv_xmm->en_mxcsr_mask;
-
-	/* FPU registers */
-	for (i = 0; i < 8; ++i)
-		bcopy(sv_xmm->sv_fp[i].fp_acc.fp_bytes, fpregs->fpr_acc[i], 10);
-
-	/* SSE registers */
-	for (i = 0; i < 16; ++i)
-		bcopy(sv_xmm->sv_xmm[i].xmm_bytes, fpregs->fpr_xacc[i], 16);
-}
-
-/* internalize from fpregs into sv_xmm */
-static void
-set_fpregs_xmm(struct fpreg *fpregs, struct savefpu *sv_xmm)
-{
-	struct envxmm *penv_xmm = &sv_xmm->sv_env;
-	struct envxmm *penv_fpreg = (struct envxmm *)&fpregs->fpr_env;
-	int i;
-
-	/* fpregs -> pcb */
-	/* FPU control/status */
-	penv_xmm->en_cw = penv_fpreg->en_cw;
-	penv_xmm->en_sw = penv_fpreg->en_sw;
-	penv_xmm->en_tw = penv_fpreg->en_tw;
-	penv_xmm->en_opcode = penv_fpreg->en_opcode;
-	penv_xmm->en_rip = penv_fpreg->en_rip;
-	penv_xmm->en_rdp = penv_fpreg->en_rdp;
-	penv_xmm->en_mxcsr = penv_fpreg->en_mxcsr;
-	penv_xmm->en_mxcsr_mask = penv_fpreg->en_mxcsr_mask & cpu_mxcsr_mask;
-
-	/* FPU registers */
-	for (i = 0; i < 8; ++i)
-		bcopy(fpregs->fpr_acc[i], sv_xmm->sv_fp[i].fp_acc.fp_bytes, 10);
-
-	/* SSE registers */
-	for (i = 0; i < 16; ++i)
-		bcopy(fpregs->fpr_xacc[i], sv_xmm->sv_xmm[i].xmm_bytes, 16);
-}
-
-/* externalize from td->pcb */
-int
-fill_fpregs(struct thread *td, struct fpreg *fpregs)
-{
-
-	KASSERT(td == curthread || TD_IS_SUSPENDED(td) ||
-	    P_SHOULDSTOP(td->td_proc),
-	    ("not suspended thread %p", td));
-	fpugetregs(td);
-	fill_fpregs_xmm(get_pcb_user_save_td(td), fpregs);
-	return (0);
-}
-
-/* internalize to td->pcb */
-int
-set_fpregs(struct thread *td, struct fpreg *fpregs)
-{
-
-	critical_enter();
-	set_fpregs_xmm(fpregs, get_pcb_user_save_td(td));
-	fpuuserinited(td);
-	critical_exit();
-	return (0);
-}
-
-/*
- * Get machine context.
- */
-int
-get_mcontext(struct thread *td, mcontext_t *mcp, int flags)
-{
-	struct pcb *pcb;
-	struct trapframe *tp;
-
-	pcb = td->td_pcb;
-	tp = td->td_frame;
-	PROC_LOCK(curthread->td_proc);
-	mcp->mc_onstack = sigonstack(tp->tf_rsp);
-	PROC_UNLOCK(curthread->td_proc);
-	mcp->mc_r15 = tp->tf_r15;
-	mcp->mc_r14 = tp->tf_r14;
-	mcp->mc_r13 = tp->tf_r13;
-	mcp->mc_r12 = tp->tf_r12;
-	mcp->mc_r11 = tp->tf_r11;
-	mcp->mc_r10 = tp->tf_r10;
-	mcp->mc_r9  = tp->tf_r9;
-	mcp->mc_r8  = tp->tf_r8;
-	mcp->mc_rdi = tp->tf_rdi;
-	mcp->mc_rsi = tp->tf_rsi;
-	mcp->mc_rbp = tp->tf_rbp;
-	mcp->mc_rbx = tp->tf_rbx;
-	mcp->mc_rcx = tp->tf_rcx;
-	mcp->mc_rflags = tp->tf_rflags;
-	if (flags & GET_MC_CLEAR_RET) {
-		mcp->mc_rax = 0;
-		mcp->mc_rdx = 0;
-		mcp->mc_rflags &= ~PSL_C;
-	} else {
-		mcp->mc_rax = tp->tf_rax;
-		mcp->mc_rdx = tp->tf_rdx;
-	}
-	mcp->mc_rip = tp->tf_rip;
-	mcp->mc_cs = tp->tf_cs;
-	mcp->mc_rsp = tp->tf_rsp;
-	mcp->mc_ss = tp->tf_ss;
-	mcp->mc_ds = tp->tf_ds;
-	mcp->mc_es = tp->tf_es;
-	mcp->mc_fs = tp->tf_fs;
-	mcp->mc_gs = tp->tf_gs;
-	mcp->mc_flags = tp->tf_flags;
-	mcp->mc_len = sizeof(*mcp);
-	get_fpcontext(td, mcp, NULL, 0);
-	update_pcb_bases(pcb);
-	mcp->mc_fsbase = pcb->pcb_fsbase;
-	mcp->mc_gsbase = pcb->pcb_gsbase;
-	mcp->mc_xfpustate = 0;
-	mcp->mc_xfpustate_len = 0;
-	bzero(mcp->mc_spare, sizeof(mcp->mc_spare));
-	return (0);
-}
-
-/*
- * Set machine context.
- *
- * However, we don't set any but the user modifiable flags, and we won't
- * touch the cs selector.
- */
-int
-set_mcontext(struct thread *td, mcontext_t *mcp)
-{
-	struct pcb *pcb;
-	struct trapframe *tp;
-	char *xfpustate;
-	long rflags;
-	int ret;
-
-	pcb = td->td_pcb;
-	tp = td->td_frame;
-	if (mcp->mc_len != sizeof(*mcp) ||
-	    (mcp->mc_flags & ~_MC_FLAG_MASK) != 0)
-		return (EINVAL);
-	rflags = (mcp->mc_rflags & PSL_USERCHANGE) |
-	    (tp->tf_rflags & ~PSL_USERCHANGE);
-	if (mcp->mc_flags & _MC_HASFPXSTATE) {
-		if (mcp->mc_xfpustate_len > cpu_max_ext_state_size -
-		    sizeof(struct savefpu))
-			return (EINVAL);
-		xfpustate = __builtin_alloca(mcp->mc_xfpustate_len);
-		ret = copyin((void *)mcp->mc_xfpustate, xfpustate,
-		    mcp->mc_xfpustate_len);
-		if (ret != 0)
-			return (ret);
-	} else
-		xfpustate = NULL;
-	ret = set_fpcontext(td, mcp, xfpustate, mcp->mc_xfpustate_len);
-	if (ret != 0)
-		return (ret);
-	tp->tf_r15 = mcp->mc_r15;
-	tp->tf_r14 = mcp->mc_r14;
-	tp->tf_r13 = mcp->mc_r13;
-	tp->tf_r12 = mcp->mc_r12;
-	tp->tf_r11 = mcp->mc_r11;
-	tp->tf_r10 = mcp->mc_r10;
-	tp->tf_r9  = mcp->mc_r9;
-	tp->tf_r8  = mcp->mc_r8;
-	tp->tf_rdi = mcp->mc_rdi;
-	tp->tf_rsi = mcp->mc_rsi;
-	tp->tf_rbp = mcp->mc_rbp;
-	tp->tf_rbx = mcp->mc_rbx;
-	tp->tf_rdx = mcp->mc_rdx;
-	tp->tf_rcx = mcp->mc_rcx;
-	tp->tf_rax = mcp->mc_rax;
-	tp->tf_rip = mcp->mc_rip;
-	tp->tf_rflags = rflags;
-	tp->tf_rsp = mcp->mc_rsp;
-	tp->tf_ss = mcp->mc_ss;
-	tp->tf_flags = mcp->mc_flags;
-	if (tp->tf_flags & TF_HASSEGS) {
-		tp->tf_ds = mcp->mc_ds;
-		tp->tf_es = mcp->mc_es;
-		tp->tf_fs = mcp->mc_fs;
-		tp->tf_gs = mcp->mc_gs;
-	}
-	set_pcb_flags(pcb, PCB_FULL_IRET);
-	if (mcp->mc_flags & _MC_HASBASES) {
-		pcb->pcb_fsbase = mcp->mc_fsbase;
-		pcb->pcb_gsbase = mcp->mc_gsbase;
-	}
-	return (0);
-}
-
-static void
-get_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpusave,
-    size_t xfpusave_len)
-{
-	size_t max_len, len;
-
-	mcp->mc_ownedfp = fpugetregs(td);
-	bcopy(get_pcb_user_save_td(td), &mcp->mc_fpstate[0],
-	    sizeof(mcp->mc_fpstate));
-	mcp->mc_fpformat = fpuformat();
-	if (!use_xsave || xfpusave_len == 0)
-		return;
-	max_len = cpu_max_ext_state_size - sizeof(struct savefpu);
-	len = xfpusave_len;
-	if (len > max_len) {
-		len = max_len;
-		bzero(xfpusave + max_len, len - max_len);
-	}
-	mcp->mc_flags |= _MC_HASFPXSTATE;
-	mcp->mc_xfpustate_len = len;
-	bcopy(get_pcb_user_save_td(td) + 1, xfpusave, len);
-}
-
-static int
-set_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpustate,
-    size_t xfpustate_len)
-{
-	int error;
-
-	if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
-		return (0);
-	else if (mcp->mc_fpformat != _MC_FPFMT_XMM)
-		return (EINVAL);
-	else if (mcp->mc_ownedfp == _MC_FPOWNED_NONE) {
-		/* We don't care what state is left in the FPU or PCB. */
-		fpstate_drop(td);
-		error = 0;
-	} else if (mcp->mc_ownedfp == _MC_FPOWNED_FPU ||
-	    mcp->mc_ownedfp == _MC_FPOWNED_PCB) {
-		error = fpusetregs(td, (struct savefpu *)&mcp->mc_fpstate,
-		    xfpustate, xfpustate_len);
-	} else
-		return (EINVAL);
-	return (error);
-}
-
-void
-fpstate_drop(struct thread *td)
-{
-
-	KASSERT(PCB_USER_FPU(td->td_pcb), ("fpstate_drop: kernel-owned fpu"));
-	critical_enter();
-	if (PCPU_GET(fpcurthread) == td)
-		fpudrop();
-	/*
-	 * XXX force a full drop of the fpu.  The above only drops it if we
-	 * owned it.
-	 *
-	 * XXX I don't much like fpugetuserregs()'s semantics of doing a full
-	 * drop.  Dropping only to the pcb matches fnsave's behaviour.
-	 * We only need to drop to !PCB_INITDONE in sendsig().  But
-	 * sendsig() is the only caller of fpugetuserregs()... perhaps we just
-	 * have too many layers.
-	 */
-	clear_pcb_flags(curthread->td_pcb,
-	    PCB_FPUINITDONE | PCB_USERFPUINITDONE);
-	critical_exit();
-}
-
-int
-fill_dbregs(struct thread *td, struct dbreg *dbregs)
-{
-	struct pcb *pcb;
-
-	if (td == NULL) {
-		dbregs->dr[0] = rdr0();
-		dbregs->dr[1] = rdr1();
-		dbregs->dr[2] = rdr2();
-		dbregs->dr[3] = rdr3();
-		dbregs->dr[6] = rdr6();
-		dbregs->dr[7] = rdr7();
-	} else {
-		pcb = td->td_pcb;
-		dbregs->dr[0] = pcb->pcb_dr0;
-		dbregs->dr[1] = pcb->pcb_dr1;
-		dbregs->dr[2] = pcb->pcb_dr2;
-		dbregs->dr[3] = pcb->pcb_dr3;
-		dbregs->dr[6] = pcb->pcb_dr6;
-		dbregs->dr[7] = pcb->pcb_dr7;
-	}
-	dbregs->dr[4] = 0;
-	dbregs->dr[5] = 0;
-	dbregs->dr[8] = 0;
-	dbregs->dr[9] = 0;
-	dbregs->dr[10] = 0;
-	dbregs->dr[11] = 0;
-	dbregs->dr[12] = 0;
-	dbregs->dr[13] = 0;
-	dbregs->dr[14] = 0;
-	dbregs->dr[15] = 0;
-	return (0);
-}
-
-int
-set_dbregs(struct thread *td, struct dbreg *dbregs)
-{
-	struct pcb *pcb;
-	int i;
-
-	if (td == NULL) {
-		load_dr0(dbregs->dr[0]);
-		load_dr1(dbregs->dr[1]);
-		load_dr2(dbregs->dr[2]);
-		load_dr3(dbregs->dr[3]);
-		load_dr6(dbregs->dr[6]);
-		load_dr7(dbregs->dr[7]);
-	} else {
-		/*
-		 * Don't let an illegal value for dr7 get set.  Specifically,
-		 * check for undefined settings.  Setting these bit patterns
-		 * result in undefined behaviour and can lead to an unexpected
-		 * TRCTRAP or a general protection fault right here.
-		 * Upper bits of dr6 and dr7 must not be set
-		 */
-		for (i = 0; i < 4; i++) {
-			if (DBREG_DR7_ACCESS(dbregs->dr[7], i) == 0x02)
-				return (EINVAL);
-			if (td->td_frame->tf_cs == _ucode32sel &&
-			    DBREG_DR7_LEN(dbregs->dr[7], i) == DBREG_DR7_LEN_8)
-				return (EINVAL);
-		}
-		if ((dbregs->dr[6] & 0xffffffff00000000ul) != 0 ||
-		    (dbregs->dr[7] & 0xffffffff00000000ul) != 0)
-			return (EINVAL);
-
-		pcb = td->td_pcb;
-
-		/*
-		 * Don't let a process set a breakpoint that is not within the
-		 * process's address space.  If a process could do this, it
-		 * could halt the system by setting a breakpoint in the kernel
-		 * (if ddb was enabled).  Thus, we need to check to make sure
-		 * that no breakpoints are being enabled for addresses outside
-		 * process's address space.
-		 *
-		 * XXX - what about when the watched area of the user's
-		 * address space is written into from within the kernel
-		 * ... wouldn't that still cause a breakpoint to be generated
-		 * from within kernel mode?
-		 */
-
-		if (DBREG_DR7_ENABLED(dbregs->dr[7], 0)) {
-			/* dr0 is enabled */
-			if (dbregs->dr[0] >= VM_MAXUSER_ADDRESS)
-				return (EINVAL);
-		}
-		if (DBREG_DR7_ENABLED(dbregs->dr[7], 1)) {
-			/* dr1 is enabled */
-			if (dbregs->dr[1] >= VM_MAXUSER_ADDRESS)
-				return (EINVAL);
-		}
-		if (DBREG_DR7_ENABLED(dbregs->dr[7], 2)) {
-			/* dr2 is enabled */
-			if (dbregs->dr[2] >= VM_MAXUSER_ADDRESS)
-				return (EINVAL);
-		}
-		if (DBREG_DR7_ENABLED(dbregs->dr[7], 3)) {
-			/* dr3 is enabled */
-			if (dbregs->dr[3] >= VM_MAXUSER_ADDRESS)
-				return (EINVAL);
-		}
-
-		pcb->pcb_dr0 = dbregs->dr[0];
-		pcb->pcb_dr1 = dbregs->dr[1];
-		pcb->pcb_dr2 = dbregs->dr[2];
-		pcb->pcb_dr3 = dbregs->dr[3];
-		pcb->pcb_dr6 = dbregs->dr[6];
-		pcb->pcb_dr7 = dbregs->dr[7];
-
-		set_pcb_flags(pcb, PCB_DBREGS);
-	}
-
-	return (0);
-}
-
-void
-reset_dbregs(void)
-{
-
-	load_dr7(0);	/* Turn off the control bits first */
-	load_dr0(0);
-	load_dr1(0);
-	load_dr2(0);
-	load_dr3(0);
-	load_dr6(0);
-}
-
-/*
- * Return > 0 if a hardware breakpoint has been hit, and the
- * breakpoint was in user space.  Return 0, otherwise.
- */
-int
-user_dbreg_trap(register_t dr6)
-{
-        u_int64_t dr7;
-        u_int64_t bp;       /* breakpoint bits extracted from dr6 */
-        int nbp;            /* number of breakpoints that triggered */
-        caddr_t addr[4];    /* breakpoint addresses */
-        int i;
-
-        bp = dr6 & DBREG_DR6_BMASK;
-        if (bp == 0) {
-                /*
-                 * None of the breakpoint bits are set meaning this
-                 * trap was not caused by any of the debug registers
-                 */
-                return 0;
-        }
-
-        dr7 = rdr7();
-        if ((dr7 & 0x000000ff) == 0) {
-                /*
-                 * all GE and LE bits in the dr7 register are zero,
-                 * thus the trap couldn't have been caused by the
-                 * hardware debug registers
-                 */
-                return 0;
-        }
-
-        nbp = 0;
-
-        /*
-         * at least one of the breakpoints were hit, check to see
-         * which ones and if any of them are user space addresses
-         */
-
-        if (bp & 0x01) {
-                addr[nbp++] = (caddr_t)rdr0();
-        }
-        if (bp & 0x02) {
-                addr[nbp++] = (caddr_t)rdr1();
-        }
-        if (bp & 0x04) {
-                addr[nbp++] = (caddr_t)rdr2();
-        }
-        if (bp & 0x08) {
-                addr[nbp++] = (caddr_t)rdr3();
-        }
-
-        for (i = 0; i < nbp; i++) {
-                if (addr[i] < (caddr_t)VM_MAXUSER_ADDRESS) {
-                        /*
-                         * addr[i] is in user space
-                         */
-                        return nbp;
-                }
-        }
-
-        /*
-         * None of the breakpoints are in user space.
-         */
-        return 0;
-}
-
 /*
  * The pcb_flags is only modified by current thread, or by other threads
  * when current thread is stopped.  However, current thread may change it
diff --git a/sys/amd64/amd64/ptrace_machdep.c b/sys/amd64/amd64/ptrace_machdep.c
index 5a552b03c90c..74fd48c68492 100644
--- a/sys/amd64/amd64/ptrace_machdep.c
+++ b/sys/amd64/amd64/ptrace_machdep.c
@@ -32,7 +32,9 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/systm.h>
+#include <sys/lock.h>
 #include <sys/malloc.h>
+#include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/ptrace.h>
 #include <sys/sysent.h>
@@ -278,3 +280,34 @@ cpu_ptrace(struct thread *td, int req, void *addr, int data)
 
 	return (error);
 }
+
+int
+ptrace_set_pc(struct thread *td, unsigned long addr)
+{
+
+	td->td_frame->tf_rip = addr;
+	set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
+	return (0);
+}
+
+int
+ptrace_single_step(struct thread *td)
+{
+
+	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
+	if ((td->td_frame->tf_rflags & PSL_T) == 0) {
+		td->td_frame->tf_rflags |= PSL_T;
+		td->td_dbgflags |= TDB_STEP;
+	}
+	return (0);
+}
+
+int
+ptrace_clear_single_step(struct thread *td)
+{
+
+	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
+	td->td_frame->tf_rflags &= ~PSL_T;
+	td->td_dbgflags &= ~TDB_STEP;
+	return (0);
+}
diff --git a/sys/conf/files.amd64 b/sys/conf/files.amd64
index b50034f38d96..c17730b37409 100644
--- a/sys/conf/files.amd64
+++ b/sys/conf/files.amd64
@@ -83,6 +83,7 @@ amd64/amd64/efirt_machdep.c	optional	efirt
 amd64/amd64/efirt_support.S	optional	efirt
 amd64/amd64/elf_machdep.c	standard
 amd64/amd64/exception.S		standard
+amd64/amd64/exec_machdep.c	standard
 amd64/amd64/fpu.c		standard
 amd64/amd64/gdb_machdep.c	optional	gdb
 amd64/amd64/in_cksum.c		optional	inet | inet6