xref: /xnu-10002.61.3/bsd/kern/kern_sig.c (revision 0f4c859e951fba394238ab619495c4e1d54d0f34)

/*
 * Copyright (c) 1995-2016 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1982, 1986, 1989, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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.
 *
 *	@(#)kern_sig.c	8.7 (Berkeley) 4/18/94
 */
/*
 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */

#define SIGPROP         /* include signal properties table */
#include <sys/param.h>
#include <sys/resourcevar.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/systm.h>
#include <sys/timeb.h>
#include <sys/times.h>
#include <sys/acct.h>
#include <sys/file_internal.h>
#include <sys/kernel.h>
#include <sys/wait.h>
#include <sys/signalvar.h>
#include <sys/syslog.h>
#include <sys/stat.h>
#include <sys/lock.h>
#include <sys/kdebug.h>
#include <sys/reason.h>

#include <sys/mount.h>
#include <sys/sysproto.h>

#include <security/audit/audit.h>

#include <kern/cpu_number.h>

#include <sys/vm.h>
#include <sys/user.h>           /* for coredump */
#include <kern/ast.h>           /* for APC support */
#include <kern/kalloc.h>
#include <kern/task.h>          /* extern void   *get_bsdtask_info(task_t); */
#include <kern/thread.h>
#include <kern/sched_prim.h>
#include <kern/thread_call.h>
#include <kern/policy_internal.h>
#include <kern/sync_sema.h>

#include <os/log.h>

#include <mach/exception.h>
#include <mach/task.h>
#include <mach/thread_act.h>
#include <libkern/OSAtomic.h>

#include <sys/sdt.h>
#include <sys/codesign.h>
#include <sys/random.h>
#include <libkern/section_keywords.h>

#if CONFIG_MACF
#include <security/mac_framework.h>
#endif

/*
 * Missing prototypes that Mach should export
 *
 * +++
 */
extern int thread_enable_fpe(thread_t act, int onoff);
extern kern_return_t get_signalact(task_t, thread_t *, int);
extern unsigned int get_useraddr(void);
extern boolean_t task_did_exec(task_t task);
extern boolean_t task_is_exec_copy(task_t task);
extern void vm_shared_region_reslide_stale(boolean_t driverkit);

/*
 * ---
 */

extern void doexception(int exc, mach_exception_code_t code,
    mach_exception_subcode_t sub);

static void stop(proc_t, proc_t);
static int cansignal_nomac(proc_t, kauth_cred_t, proc_t, int);
int cansignal(proc_t, kauth_cred_t, proc_t, int);
int killpg1(proc_t, int, int, int, int);
kern_return_t do_bsdexception(int, int, int);
void __posix_sem_syscall_return(kern_return_t);
char *proc_name_address(void *p);

static int      filt_sigattach(struct knote *kn, struct kevent_qos_s *kev);
static void     filt_sigdetach(struct knote *kn);
static int      filt_signal(struct knote *kn, long hint);
static int      filt_signaltouch(struct knote *kn, struct kevent_qos_s *kev);
static int      filt_signalprocess(struct knote *kn, struct kevent_qos_s *kev);

SECURITY_READ_ONLY_EARLY(struct filterops) sig_filtops = {
	.f_attach = filt_sigattach,
	.f_detach = filt_sigdetach,
	.f_event = filt_signal,
	.f_touch = filt_signaltouch,
	.f_process = filt_signalprocess,
};

/* structures  and fns for killpg1 iterartion callback and filters */
struct killpg1_filtargs {
	bool posix;
	proc_t curproc;
};

struct killpg1_iterargs {
	proc_t curproc;
	kauth_cred_t uc;
	int signum;
	int nfound;
};

static int killpg1_allfilt(proc_t p, void * arg);
static int killpg1_callback(proc_t p, void * arg);

static int pgsignal_callback(proc_t p, void * arg);
static kern_return_t get_signalthread(proc_t, int, thread_t *);


/* flags for psignal_internal */
#define PSIG_LOCKED     0x1
#define PSIG_VFORK      0x2
#define PSIG_THREAD     0x4
#define PSIG_TRY_THREAD 0x8

static os_reason_t build_signal_reason(int signum, const char *procname);
static void psignal_internal(proc_t p, task_t task, thread_t thread, int flavor, int signum, os_reason_t signal_reason);

/*
 * NOTE: Source and target may *NOT* overlap! (target is smaller)
 */
static void
sigaltstack_kern_to_user32(struct kern_sigaltstack *in, struct user32_sigaltstack *out)
{
	out->ss_sp          = CAST_DOWN_EXPLICIT(user32_addr_t, in->ss_sp);
	out->ss_size    = CAST_DOWN_EXPLICIT(user32_size_t, in->ss_size);
	out->ss_flags   = in->ss_flags;
}

static void
sigaltstack_kern_to_user64(struct kern_sigaltstack *in, struct user64_sigaltstack *out)
{
	out->ss_sp          = in->ss_sp;
	out->ss_size    = in->ss_size;
	out->ss_flags   = in->ss_flags;
}

/*
 * NOTE: Source and target may are permitted to overlap! (source is smaller);
 * this works because we copy fields in order from the end of the struct to
 * the beginning.
 */
static void
sigaltstack_user32_to_kern(struct user32_sigaltstack *in, struct kern_sigaltstack *out)
{
	out->ss_flags   = in->ss_flags;
	out->ss_size    = in->ss_size;
	out->ss_sp              = CAST_USER_ADDR_T(in->ss_sp);
}
static void
sigaltstack_user64_to_kern(struct user64_sigaltstack *in, struct kern_sigaltstack *out)
{
	out->ss_flags   = in->ss_flags;
	out->ss_size    = (user_size_t)in->ss_size;
	out->ss_sp      = (user_addr_t)in->ss_sp;
}

static void
sigaction_kern_to_user32(struct kern_sigaction *in, struct user32_sigaction *out)
{
	/* This assumes 32 bit __sa_handler is of type sig_t */
	out->__sigaction_u.__sa_handler = CAST_DOWN_EXPLICIT(user32_addr_t, in->__sigaction_u.__sa_handler);
	out->sa_mask = in->sa_mask;
	out->sa_flags = in->sa_flags;
}
static void
sigaction_kern_to_user64(struct kern_sigaction *in, struct user64_sigaction *out)
{
	/* This assumes 32 bit __sa_handler is of type sig_t */
	out->__sigaction_u.__sa_handler = in->__sigaction_u.__sa_handler;
	out->sa_mask = in->sa_mask;
	out->sa_flags = in->sa_flags;
}

static void
__sigaction_user32_to_kern(struct __user32_sigaction *in, struct __kern_sigaction *out)
{
	out->__sigaction_u.__sa_handler = CAST_USER_ADDR_T(in->__sigaction_u.__sa_handler);
	out->sa_tramp = CAST_USER_ADDR_T(in->sa_tramp);
	out->sa_mask = in->sa_mask;
	out->sa_flags = in->sa_flags;

	kern_return_t kr;
	kr = machine_thread_function_pointers_convert_from_user(current_thread(),
	    &out->sa_tramp, 1);
	assert(kr == KERN_SUCCESS);
}

static void
__sigaction_user64_to_kern(struct __user64_sigaction *in, struct __kern_sigaction *out)
{
	out->__sigaction_u.__sa_handler = (user_addr_t)in->__sigaction_u.__sa_handler;
	out->sa_tramp = (user_addr_t)in->sa_tramp;
	out->sa_mask = in->sa_mask;
	out->sa_flags = in->sa_flags;

	kern_return_t kr;
	kr = machine_thread_function_pointers_convert_from_user(current_thread(),
	    &out->sa_tramp, 1);
	assert(kr == KERN_SUCCESS);
}

#if SIGNAL_DEBUG
void ram_printf(int);
int ram_debug = 0;
unsigned int rdebug_proc = 0;
void
ram_printf(int x)
{
	printf("x is %d", x);
}
#endif /* SIGNAL_DEBUG */


void
signal_setast(thread_t sig_actthread)
{
	act_set_astbsd(sig_actthread);
}

static int
cansignal_nomac(proc_t src, kauth_cred_t uc_src, proc_t dst, int signum)
{
	/* you can signal yourself */
	if (src == dst) {
		return 1;
	}

	/* you can't send the init proc SIGKILL, even if root */
	if (signum == SIGKILL && dst == initproc) {
		return 0;
	}

	/* otherwise, root can always signal */
	if (kauth_cred_issuser(uc_src)) {
		return 1;
	}

	/* processes in the same session can send SIGCONT to each other */
	if (signum == SIGCONT && proc_sessionid(src) == proc_sessionid(dst)) {
		return 1;
	}

#if XNU_TARGET_OS_IOS
	// Allow debugging of third party drivers on iOS
	if (proc_is_third_party_debuggable_driver(dst)) {
		return 1;
	}
#endif /* XNU_TARGET_OS_IOS */

	/* the source process must be authorized to signal the target */
	{
		int allowed = 0;
		kauth_cred_t uc_dst = NOCRED, uc_ref = NOCRED;

		uc_dst = uc_ref = kauth_cred_proc_ref(dst);

		/*
		 * If the real or effective UID of the sender matches the real or saved
		 * UID of the target, allow the signal to be sent.
		 */
		if (kauth_cred_getruid(uc_src) == kauth_cred_getruid(uc_dst) ||
		    kauth_cred_getruid(uc_src) == kauth_cred_getsvuid(uc_dst) ||
		    kauth_cred_getuid(uc_src) == kauth_cred_getruid(uc_dst) ||
		    kauth_cred_getuid(uc_src) == kauth_cred_getsvuid(uc_dst)) {
			allowed = 1;
		}

		if (uc_ref != NOCRED) {
			kauth_cred_unref(&uc_ref);
			uc_ref = NOCRED;
		}

		return allowed;
	}
}

/*
 * Can process `src`, with ucred `uc_src`, send the signal `signum` to process
 * `dst`?  The ucred is referenced by the caller so internal fileds can be used
 * safely.
 */
int
cansignal(proc_t src, kauth_cred_t uc_src, proc_t dst, int signum)
{
#if CONFIG_MACF
	if (mac_proc_check_signal(src, dst, signum)) {
		return 0;
	}
#endif

	return cansignal_nomac(src, uc_src, dst, signum);
}

/*
 * <rdar://problem/21952708> Some signals can be restricted from being handled,
 * forcing the default action for that signal. This behavior applies only to
 * non-root (EUID != 0) processes, and is configured with the "sigrestrict=x"
 * bootarg:
 *
 *   0 (default): Disallow use of restricted signals. Trying to register a handler
 *		returns ENOTSUP, which userspace may use to take special action (e.g. abort).
 *   1: As above, but return EINVAL. Restricted signals behave similarly to SIGKILL.
 *   2: Usual POSIX semantics.
 */
static TUNABLE(unsigned, sigrestrict_arg, "sigrestrict", 0);

#if XNU_PLATFORM_WatchOS
static int
sigrestrictmask(void)
{
	if (kauth_getuid() != 0 && sigrestrict_arg != 2) {
		return SIGRESTRICTMASK;
	}
	return 0;
}

static int
signal_is_restricted(proc_t p, int signum)
{
	if (sigmask(signum) & sigrestrictmask()) {
		if (sigrestrict_arg == 0 &&
		    task_get_apptype(proc_task(p)) == TASK_APPTYPE_APP_DEFAULT) {
			return ENOTSUP;
		} else {
			return EINVAL;
		}
	}
	return 0;
}

#else

static inline int
signal_is_restricted(proc_t p, int signum)
{
	(void)p;
	(void)signum;
	return 0;
}
#endif /* !XNU_PLATFORM_WatchOS */

/*
 * Returns:	0			Success
 *		EINVAL
 *	copyout:EFAULT
 *	copyin:EFAULT
 *
 * Notes:	Uses current thread as a parameter to inform PPC to enable
 *		FPU exceptions via setsigvec(); this operation is not proxy
 *		safe!
 */
/* ARGSUSED */
int
sigaction(proc_t p, struct sigaction_args *uap, __unused int32_t *retval)
{
	struct kern_sigaction vec;
	struct __kern_sigaction __vec;

	struct kern_sigaction *sa = &vec;
	struct sigacts *ps = &p->p_sigacts;

	int signum;
	int bit, error = 0;
	uint32_t sigreturn_validation = PS_SIGRETURN_VALIDATION_DEFAULT;

	signum = uap->signum;
	if (signum <= 0 || signum >= NSIG ||
	    signum == SIGKILL || signum == SIGSTOP) {
		return EINVAL;
	}

	if (uap->nsa) {
		if (IS_64BIT_PROCESS(p)) {
			struct __user64_sigaction       __vec64;
			error = copyin(uap->nsa, &__vec64, sizeof(__vec64));
			__sigaction_user64_to_kern(&__vec64, &__vec);
		} else {
			struct __user32_sigaction       __vec32;
			error = copyin(uap->nsa, &__vec32, sizeof(__vec32));
			__sigaction_user32_to_kern(&__vec32, &__vec);
		}
		if (error) {
			return error;
		}

		sigreturn_validation = (__vec.sa_flags & SA_VALIDATE_SIGRETURN_FROM_SIGTRAMP) ?
		    PS_SIGRETURN_VALIDATION_ENABLED : PS_SIGRETURN_VALIDATION_DISABLED;
		__vec.sa_flags &= SA_USERSPACE_MASK; /* Only pass on valid sa_flags */

		if ((__vec.sa_flags & SA_SIGINFO) || __vec.sa_handler != SIG_DFL) {
			if ((error = signal_is_restricted(p, signum))) {
				if (error == ENOTSUP) {
					printf("%s(%d): denied attempt to register action for signal %d\n",
					    proc_name_address(p), proc_pid(p), signum);
				}
				return error;
			}
		}
	}

	if (uap->osa) {
		sa->sa_handler = SIGACTION(p, signum);
		sa->sa_mask = ps->ps_catchmask[signum];
		bit = sigmask(signum);
		sa->sa_flags = 0;
		if ((ps->ps_sigonstack & bit) != 0) {
			sa->sa_flags |= SA_ONSTACK;
		}
		if ((ps->ps_sigintr & bit) == 0) {
			sa->sa_flags |= SA_RESTART;
		}
		if (ps->ps_siginfo & bit) {
			sa->sa_flags |= SA_SIGINFO;
		}
		if (ps->ps_signodefer & bit) {
			sa->sa_flags |= SA_NODEFER;
		}
		if ((signum == SIGCHLD) && (p->p_flag & P_NOCLDSTOP)) {
			sa->sa_flags |= SA_NOCLDSTOP;
		}
		if ((signum == SIGCHLD) && (p->p_flag & P_NOCLDWAIT)) {
			sa->sa_flags |= SA_NOCLDWAIT;
		}

		if (IS_64BIT_PROCESS(p)) {
			struct user64_sigaction vec64 = {};
			sigaction_kern_to_user64(sa, &vec64);
			error = copyout(&vec64, uap->osa, sizeof(vec64));
		} else {
			struct user32_sigaction vec32 = {};
			sigaction_kern_to_user32(sa, &vec32);
			error = copyout(&vec32, uap->osa, sizeof(vec32));
		}
		if (error) {
			return error;
		}
	}

	if (uap->nsa) {
		uint32_t old_sigreturn_validation = atomic_load_explicit(
			&ps->ps_sigreturn_validation, memory_order_relaxed);
		if (old_sigreturn_validation == PS_SIGRETURN_VALIDATION_DEFAULT) {
			atomic_compare_exchange_strong_explicit(&ps->ps_sigreturn_validation,
			    &old_sigreturn_validation, sigreturn_validation,
			    memory_order_relaxed, memory_order_relaxed);
		}
		error = setsigvec(p, current_thread(), signum, &__vec, FALSE);
	}

	return error;
}

/* Routines to manipulate bits on all threads */
int
clear_procsiglist(proc_t p, int bit, boolean_t in_signalstart)
{
	struct uthread * uth;

	proc_lock(p);
	if (!in_signalstart) {
		proc_signalstart(p, 1);
	}


	TAILQ_FOREACH(uth, &p->p_uthlist, uu_list) {
		uth->uu_siglist &= ~bit;
	}
	p->p_siglist &= ~bit;
	if (!in_signalstart) {
		proc_signalend(p, 1);
	}
	proc_unlock(p);

	return 0;
}


static int
unblock_procsigmask(proc_t p, int bit)
{
	struct uthread * uth;

	proc_lock(p);
	proc_signalstart(p, 1);


	TAILQ_FOREACH(uth, &p->p_uthlist, uu_list) {
		uth->uu_sigmask &= ~bit;
	}
	p->p_sigmask &= ~bit;

	proc_signalend(p, 1);
	proc_unlock(p);
	return 0;
}

static int
block_procsigmask(proc_t p, int bit)
{
	struct uthread * uth;

	proc_lock(p);
	proc_signalstart(p, 1);


	TAILQ_FOREACH(uth, &p->p_uthlist, uu_list) {
		uth->uu_sigmask |= bit;
	}
	p->p_sigmask |=  bit;

	proc_signalend(p, 1);
	proc_unlock(p);
	return 0;
}

int
set_procsigmask(proc_t p, int bit)
{
	struct uthread * uth;

	proc_lock(p);
	proc_signalstart(p, 1);


	TAILQ_FOREACH(uth, &p->p_uthlist, uu_list) {
		uth->uu_sigmask = bit;
	}
	p->p_sigmask =  bit;
	proc_signalend(p, 1);
	proc_unlock(p);

	return 0;
}

/* XXX should be static? */
/*
 * Notes:	The thread parameter is used in the PPC case to select the
 *		thread on which the floating point exception will be enabled
 *		or disabled.  We can't simply take current_thread(), since
 *		this is called from posix_spawn() on the not currently running
 *		process/thread pair.
 *
 *		We mark thread as unused to alow compilation without warning
 *		on non-PPC platforms.
 */
int
setsigvec(proc_t p, __unused thread_t thread, int signum, struct __kern_sigaction *sa, boolean_t in_sigstart)
{
	struct sigacts *ps = &p->p_sigacts;
	int bit;

	assert(signum < NSIG);

	if ((signum == SIGKILL || signum == SIGSTOP) &&
	    sa->sa_handler != SIG_DFL) {
		return EINVAL;
	}
	bit = sigmask(signum);
	/*
	 * Change setting atomically.
	 */
	proc_set_sigact_trampact(p, signum, sa->sa_handler, sa->sa_tramp);
	ps->ps_catchmask[signum] = sa->sa_mask & ~sigcantmask;
	if (sa->sa_flags & SA_SIGINFO) {
		ps->ps_siginfo |= bit;
	} else {
		ps->ps_siginfo &= ~bit;
	}
	if ((sa->sa_flags & SA_RESTART) == 0) {
		ps->ps_sigintr |= bit;
	} else {
		ps->ps_sigintr &= ~bit;
	}
	if (sa->sa_flags & SA_ONSTACK) {
		ps->ps_sigonstack |= bit;
	} else {
		ps->ps_sigonstack &= ~bit;
	}
	if (sa->sa_flags & SA_RESETHAND) {
		ps->ps_sigreset |= bit;
	} else {
		ps->ps_sigreset &= ~bit;
	}
	if (sa->sa_flags & SA_NODEFER) {
		ps->ps_signodefer |= bit;
	} else {
		ps->ps_signodefer &= ~bit;
	}
	if (signum == SIGCHLD) {
		if (sa->sa_flags & SA_NOCLDSTOP) {
			OSBitOrAtomic(P_NOCLDSTOP, &p->p_flag);
		} else {
			OSBitAndAtomic(~((uint32_t)P_NOCLDSTOP), &p->p_flag);
		}
		if ((sa->sa_flags & SA_NOCLDWAIT) || (sa->sa_handler == SIG_IGN)) {
			OSBitOrAtomic(P_NOCLDWAIT, &p->p_flag);
		} else {
			OSBitAndAtomic(~((uint32_t)P_NOCLDWAIT), &p->p_flag);
		}
	}

	/*
	 * Set bit in p_sigignore for signals that are set to SIG_IGN,
	 * and for signals set to SIG_DFL where the default is to ignore.
	 * However, don't put SIGCONT in p_sigignore,
	 * as we have to restart the process.
	 */
	if (sa->sa_handler == SIG_IGN ||
	    (sigprop[signum] & SA_IGNORE && sa->sa_handler == SIG_DFL)) {
		clear_procsiglist(p, bit, in_sigstart);
		if (signum != SIGCONT) {
			p->p_sigignore |= bit;  /* easier in psignal */
		}
		p->p_sigcatch &= ~bit;
	} else {
		p->p_sigignore &= ~bit;
		if (sa->sa_handler == SIG_DFL) {
			p->p_sigcatch &= ~bit;
		} else {
			p->p_sigcatch |= bit;
		}
	}
	return 0;
}

/*
 * Initialize signal state for process 0;
 * set to ignore signals that are ignored by default.
 */
void
siginit(proc_t p)
{
	int i;

	for (i = 1; i < NSIG; i++) {
		if (sigprop[i] & SA_IGNORE && i != SIGCONT) {
			p->p_sigignore |= sigmask(i);
		}
	}
}

/*
 * Reset signals for an exec of the specified process.
 */
void
execsigs(proc_t p, thread_t thread)
{
	struct sigacts *ps = &p->p_sigacts;
	int nc, mask;
	struct uthread *ut;

	ut = (struct uthread *)get_bsdthread_info(thread);

	/*
	 * transfer saved signal states from the process
	 * back to the current thread.
	 *
	 * NOTE: We do this without the process locked,
	 * because we are guaranteed to be single-threaded
	 * by this point in exec and the p_siglist is
	 * only accessed by threads inside the process.
	 */
	ut->uu_siglist |= p->p_siglist;
	p->p_siglist = 0;

	/*
	 * Reset caught signals.  Held signals remain held
	 * through p_sigmask (unless they were caught,
	 * and are now ignored by default).
	 */
	proc_reset_sigact(p, p->p_sigcatch);
	while (p->p_sigcatch) {
		nc = ffs((unsigned int)p->p_sigcatch);
		mask = sigmask(nc);
		p->p_sigcatch &= ~mask;
		if (sigprop[nc] & SA_IGNORE) {
			if (nc != SIGCONT) {
				p->p_sigignore |= mask;
			}
			ut->uu_siglist &= ~mask;
		}
	}

	atomic_store_explicit(&ps->ps_sigreturn_validation,
	    PS_SIGRETURN_VALIDATION_DEFAULT, memory_order_relaxed);

	/*
	 * Reset stack state to the user stack.
	 * Clear set of signals caught on the signal stack.
	 */
	/* thread */
	ut->uu_sigstk.ss_flags = SA_DISABLE;
	ut->uu_sigstk.ss_size = 0;
	ut->uu_sigstk.ss_sp = USER_ADDR_NULL;
	ut->uu_flag &= ~UT_ALTSTACK;
	/* process */
	ps->ps_sigonstack = 0;
}

/*
 * Manipulate signal mask.
 * Note that we receive new mask, not pointer,
 * and return old mask as return value;
 * the library stub does the rest.
 */
int
sigprocmask(proc_t p, struct sigprocmask_args *uap, __unused int32_t *retval)
{
	int error = 0;
	sigset_t oldmask, nmask;
	user_addr_t omask = uap->omask;
	struct uthread *ut;

	ut = current_uthread();
	oldmask  = ut->uu_sigmask;

	if (uap->mask == USER_ADDR_NULL) {
		/* just want old mask */
		goto out;
	}
	error = copyin(uap->mask, &nmask, sizeof(sigset_t));
	if (error) {
		goto out;
	}

	switch (uap->how) {
	case SIG_BLOCK:
		block_procsigmask(p, (nmask & ~sigcantmask));
		signal_setast(current_thread());
		break;

	case SIG_UNBLOCK:
		unblock_procsigmask(p, (nmask & ~sigcantmask));
		signal_setast(current_thread());
		break;

	case SIG_SETMASK:
		set_procsigmask(p, (nmask & ~sigcantmask));
		signal_setast(current_thread());
		break;

	default:
		error = EINVAL;
		break;
	}
out:
	if (!error && omask != USER_ADDR_NULL) {
		copyout(&oldmask, omask, sizeof(sigset_t));
	}
	return error;
}

int
sigpending(__unused proc_t p, struct sigpending_args *uap, __unused int32_t *retval)
{
	struct uthread *ut;
	sigset_t pendlist;

	ut = current_uthread();
	pendlist = ut->uu_siglist;

	if (uap->osv) {
		copyout(&pendlist, uap->osv, sizeof(sigset_t));
	}
	return 0;
}

/*
 * Suspend process until signal, providing mask to be set
 * in the meantime.  Note nonstandard calling convention:
 * libc stub passes mask, not pointer, to save a copyin.
 */

static int
sigcontinue(__unused int error)
{
//	struct uthread *ut = current_uthread();
	unix_syscall_return(EINTR);
}

int
sigsuspend(proc_t p, struct sigsuspend_args *uap, int32_t *retval)
{
	__pthread_testcancel(1);
	return sigsuspend_nocancel(p, (struct sigsuspend_nocancel_args *)uap, retval);
}

int
sigsuspend_nocancel(proc_t p, struct sigsuspend_nocancel_args *uap, __unused int32_t *retval)
{
	struct uthread *ut;

	ut = current_uthread();

	/*
	 * When returning from sigpause, we want
	 * the old mask to be restored after the
	 * signal handler has finished.  Thus, we
	 * save it here and mark the sigacts structure
	 * to indicate this.
	 */
	ut->uu_oldmask = ut->uu_sigmask;
	ut->uu_flag |= UT_SAS_OLDMASK;
	ut->uu_sigmask = (uap->mask & ~sigcantmask);
	(void) tsleep0((caddr_t) p, PPAUSE | PCATCH, "pause", 0, sigcontinue);
	/* always return EINTR rather than ERESTART... */
	return EINTR;
}


int
__disable_threadsignal(__unused proc_t p,
    __unused struct __disable_threadsignal_args *uap,
    __unused int32_t *retval)
{
	struct uthread *uth;

	uth = current_uthread();

	/* No longer valid to have any signal delivered */
	uth->uu_flag |= (UT_NO_SIGMASK | UT_CANCELDISABLE);

	return 0;
}

void
__pthread_testcancel(int presyscall)
{
	thread_t self = current_thread();
	struct uthread * uthread;

	uthread = (struct uthread *)get_bsdthread_info(self);


	uthread->uu_flag &= ~UT_NOTCANCELPT;

	if ((uthread->uu_flag & (UT_CANCELDISABLE | UT_CANCEL | UT_CANCELED)) == UT_CANCEL) {
		if (presyscall != 0) {
			unix_syscall_return(EINTR);
			/* NOTREACHED */
		} else {
			thread_abort_safely(self);
		}
	}
}



int
__pthread_markcancel(__unused proc_t p,
    struct __pthread_markcancel_args *uap, __unused int32_t *retval)
{
	thread_act_t target_act;
	int error = 0;
	struct uthread *uth;

	target_act = (thread_act_t)port_name_to_thread(uap->thread_port,
	    PORT_INTRANS_THREAD_IN_CURRENT_TASK);

	if (target_act == THR_ACT_NULL) {
		return ESRCH;
	}

	uth = (struct uthread *)get_bsdthread_info(target_act);

	if ((uth->uu_flag & (UT_CANCEL | UT_CANCELED)) == 0) {
		uth->uu_flag |= (UT_CANCEL | UT_NO_SIGMASK);
		if (((uth->uu_flag & UT_NOTCANCELPT) == 0)
		    && ((uth->uu_flag & UT_CANCELDISABLE) == 0)) {
			thread_abort_safely(target_act);
		}
	}

	thread_deallocate(target_act);
	return error;
}

/* if action =0 ; return the cancellation state ,
 *      if marked for cancellation, make the thread canceled
 * if action = 1 ; Enable the cancel handling
 * if action = 2; Disable the cancel handling
 */
int
__pthread_canceled(__unused proc_t p,
    struct __pthread_canceled_args *uap, __unused int32_t *retval)
{
	thread_act_t thread;
	struct uthread *uth;
	int action = uap->action;

	thread = current_thread();
	uth = (struct uthread *)get_bsdthread_info(thread);

	switch (action) {
	case 1:
		uth->uu_flag &= ~UT_CANCELDISABLE;
		return 0;
	case 2:
		uth->uu_flag |= UT_CANCELDISABLE;
		return 0;
	case 0:
	default:
		if ((uth->uu_flag & (UT_CANCELDISABLE | UT_CANCEL | UT_CANCELED)) == UT_CANCEL) {
			uth->uu_flag &= ~UT_CANCEL;
			uth->uu_flag |= (UT_CANCELED | UT_NO_SIGMASK);
			return 0;
		}
		return EINVAL;
	}
	return EINVAL;
}

__attribute__((noreturn))
void
__posix_sem_syscall_return(kern_return_t kern_result)
{
	int error = 0;

	if (kern_result == KERN_SUCCESS) {
		error = 0;
	} else if (kern_result == KERN_ABORTED) {
		error = EINTR;
	} else if (kern_result == KERN_OPERATION_TIMED_OUT) {
		error = ETIMEDOUT;
	} else {
		error = EINVAL;
	}
	unix_syscall_return(error);
	/* does not return */
}

/*
 * Returns:	0			Success
 *		EINTR
 *		ETIMEDOUT
 *		EINVAL
 *      EFAULT if timespec is NULL
 */
int
__semwait_signal(proc_t p, struct __semwait_signal_args *uap,
    int32_t *retval)
{
	__pthread_testcancel(0);
	return __semwait_signal_nocancel(p, (struct __semwait_signal_nocancel_args *)uap, retval);
}

int
__semwait_signal_nocancel(__unused proc_t p, struct __semwait_signal_nocancel_args *uap,
    __unused int32_t *retval)
{
	kern_return_t kern_result;
	mach_timespec_t then;
	struct timespec now;
	struct user_timespec ts;
	boolean_t truncated_timeout = FALSE;

	if (uap->timeout) {
		ts.tv_sec = (user_time_t)uap->tv_sec;
		ts.tv_nsec = uap->tv_nsec;

		if ((ts.tv_sec & 0xFFFFFFFF00000000ULL) != 0) {
			ts.tv_sec = 0xFFFFFFFF;
			ts.tv_nsec = 0;
			truncated_timeout = TRUE;
		}

		if (uap->relative) {
			then.tv_sec = (unsigned int)ts.tv_sec;
			then.tv_nsec = (clock_res_t)ts.tv_nsec;
		} else {
			nanotime(&now);

			/* if time has elapsed, set time to null timepsec to bailout rightaway */
			if (now.tv_sec == ts.tv_sec ?
			    now.tv_nsec > ts.tv_nsec :
			    now.tv_sec > ts.tv_sec) {
				then.tv_sec = 0;
				then.tv_nsec = 0;
			} else {
				then.tv_sec = (unsigned int)(ts.tv_sec - now.tv_sec);
				then.tv_nsec = (clock_res_t)(ts.tv_nsec - now.tv_nsec);
				if (then.tv_nsec < 0) {
					then.tv_nsec += NSEC_PER_SEC;
					then.tv_sec--;
				}
			}
		}

		if (uap->mutex_sem == 0) {
			kern_result = semaphore_timedwait_trap_internal((mach_port_name_t)uap->cond_sem, then.tv_sec, then.tv_nsec, __posix_sem_syscall_return);
		} else {
			kern_result = semaphore_timedwait_signal_trap_internal(uap->cond_sem, uap->mutex_sem, then.tv_sec, then.tv_nsec, __posix_sem_syscall_return);
		}
	} else {
		if (uap->mutex_sem == 0) {
			kern_result = semaphore_wait_trap_internal(uap->cond_sem, __posix_sem_syscall_return);
		} else {
			kern_result = semaphore_wait_signal_trap_internal(uap->cond_sem, uap->mutex_sem, __posix_sem_syscall_return);
		}
	}

	if (kern_result == KERN_SUCCESS && !truncated_timeout) {
		return 0;
	} else if (kern_result == KERN_SUCCESS && truncated_timeout) {
		return EINTR; /* simulate an exceptional condition because Mach doesn't support a longer timeout */
	} else if (kern_result == KERN_ABORTED) {
		return EINTR;
	} else if (kern_result == KERN_OPERATION_TIMED_OUT) {
		return ETIMEDOUT;
	} else {
		return EINVAL;
	}
}


int
__pthread_kill(__unused proc_t p, struct __pthread_kill_args *uap,
    __unused int32_t *retval)
{
	thread_t target_act;
	int error = 0;
	int signum = uap->sig;
	struct uthread *uth;

	target_act = (thread_t)port_name_to_thread(uap->thread_port,
	    PORT_INTRANS_OPTIONS_NONE);

	if (target_act == THREAD_NULL) {
		return ESRCH;
	}
	if ((u_int)signum >= NSIG) {
		error = EINVAL;
		goto out;
	}

	uth = (struct uthread *)get_bsdthread_info(target_act);

	if (uth->uu_flag & UT_NO_SIGMASK) {
		error = ESRCH;
		goto out;
	}

	if ((thread_get_tag(target_act) & THREAD_TAG_WORKQUEUE) && !uth->uu_workq_pthread_kill_allowed) {
		error = ENOTSUP;
		goto out;
	}

	if (signum) {
		psignal_uthread(target_act, signum);
	}
out:
	thread_deallocate(target_act);
	return error;
}


int
__pthread_sigmask(__unused proc_t p, struct __pthread_sigmask_args *uap,
    __unused int32_t *retval)
{
	user_addr_t set = uap->set;
	user_addr_t oset = uap->oset;
	sigset_t nset;
	int error = 0;
	struct uthread *ut;
	sigset_t  oldset;

	ut = current_uthread();
	oldset = ut->uu_sigmask;

	if (set == USER_ADDR_NULL) {
		/* need only old mask */
		goto out;
	}

	error = copyin(set, &nset, sizeof(sigset_t));
	if (error) {
		goto out;
	}

	switch (uap->how) {
	case SIG_BLOCK:
		ut->uu_sigmask |= (nset & ~sigcantmask);
		break;

	case SIG_UNBLOCK:
		ut->uu_sigmask &= ~(nset);
		signal_setast(current_thread());
		break;

	case SIG_SETMASK:
		ut->uu_sigmask = (nset & ~sigcantmask);
		signal_setast(current_thread());
		break;

	default:
		error = EINVAL;
	}
out:
	if (!error && oset != USER_ADDR_NULL) {
		copyout(&oldset, oset, sizeof(sigset_t));
	}

	return error;
}

/*
 * Returns:	0			Success
 *		EINVAL
 *	copyin:EFAULT
 *	copyout:EFAULT
 */
int
__sigwait(proc_t p, struct __sigwait_args *uap, int32_t *retval)
{
	__pthread_testcancel(1);
	return __sigwait_nocancel(p, (struct __sigwait_nocancel_args *)uap, retval);
}

int
__sigwait_nocancel(proc_t p, struct __sigwait_nocancel_args *uap, __unused int32_t *retval)
{
	struct uthread *ut;
	struct uthread *uth;
	int error = 0;
	sigset_t mask;
	sigset_t siglist;
	sigset_t sigw = 0;
	int signum;

	ut = current_uthread();

	if (uap->set == USER_ADDR_NULL) {
		return EINVAL;
	}

	error = copyin(uap->set, &mask, sizeof(sigset_t));
	if (error) {
		return error;
	}

	siglist = (mask & ~sigcantmask);

	if (siglist == 0) {
		return EINVAL;
	}

	proc_lock(p);

	proc_signalstart(p, 1);
	TAILQ_FOREACH(uth, &p->p_uthlist, uu_list) {
		if ((sigw = uth->uu_siglist & siglist)) {
			break;
		}
	}
	proc_signalend(p, 1);

	if (sigw) {
		/* The signal was pending on a thread */
		goto sigwait1;
	}
	/*
	 * When returning from sigwait, we want
	 * the old mask to be restored after the
	 * signal handler has finished.  Thus, we
	 * save it here and mark the sigacts structure
	 * to indicate this.
	 */
	uth = ut;               /* wait for it to be delivered to us */
	ut->uu_oldmask = ut->uu_sigmask;
	ut->uu_flag |= UT_SAS_OLDMASK;
	if (siglist == (sigset_t)0) {
		proc_unlock(p);
		return EINVAL;
	}
	/* SIGKILL and SIGSTOP are not maskable as well */
	ut->uu_sigmask = ~(siglist | sigcantmask);
	ut->uu_sigwait = siglist;

	/* No Continuations for now */
	error =  msleep((caddr_t)&ut->uu_sigwait, &p->p_mlock, PPAUSE | PCATCH, "pause", 0);

	if (error == ERESTART) {
		error = 0;
	}

	sigw = (ut->uu_sigwait & siglist);
	ut->uu_sigmask = ut->uu_oldmask;
	ut->uu_oldmask = 0;
	ut->uu_flag &= ~UT_SAS_OLDMASK;
sigwait1:
	ut->uu_sigwait = 0;
	if (!error) {
		signum = ffs((unsigned int)sigw);
		if (!signum) {
			panic("sigwait with no signal wakeup");
		}
		/* Clear the pending signal in the thread it was delivered */
		uth->uu_siglist &= ~(sigmask(signum));

#if CONFIG_DTRACE
		DTRACE_PROC2(signal__clear, int, signum, siginfo_t *, &(ut->t_dtrace_siginfo));
#endif

		proc_unlock(p);
		if (uap->sig != USER_ADDR_NULL) {
			error = copyout(&signum, uap->sig, sizeof(int));
		}
	} else {
		proc_unlock(p);
	}

	return error;
}

int
sigaltstack(__unused proc_t p, struct sigaltstack_args *uap, __unused int32_t *retval)
{
	struct kern_sigaltstack ss;
	struct kern_sigaltstack *pstk;
	int error;
	struct uthread *uth;
	int onstack;

	uth = current_uthread();

	pstk = &uth->uu_sigstk;
	if ((uth->uu_flag & UT_ALTSTACK) == 0) {
		uth->uu_sigstk.ss_flags |= SA_DISABLE;
	}
	onstack = pstk->ss_flags & SA_ONSTACK;
	if (uap->oss) {
		if (IS_64BIT_PROCESS(p)) {
			struct user64_sigaltstack ss64 = {};
			sigaltstack_kern_to_user64(pstk, &ss64);
			error = copyout(&ss64, uap->oss, sizeof(ss64));
		} else {
			struct user32_sigaltstack ss32 = {};
			sigaltstack_kern_to_user32(pstk, &ss32);
			error = copyout(&ss32, uap->oss, sizeof(ss32));
		}
		if (error) {
			return error;
		}
	}
	if (uap->nss == USER_ADDR_NULL) {
		return 0;
	}
	if (IS_64BIT_PROCESS(p)) {
		struct user64_sigaltstack ss64;
		error = copyin(uap->nss, &ss64, sizeof(ss64));
		sigaltstack_user64_to_kern(&ss64, &ss);
	} else {
		struct user32_sigaltstack ss32;
		error = copyin(uap->nss, &ss32, sizeof(ss32));
		sigaltstack_user32_to_kern(&ss32, &ss);
	}
	if (error) {
		return error;
	}
	if ((ss.ss_flags & ~SA_DISABLE) != 0) {
		return EINVAL;
	}

	if (ss.ss_flags & SA_DISABLE) {
		/* if we are here we are not in the signal handler ;so no need to check */
		if (uth->uu_sigstk.ss_flags & SA_ONSTACK) {
			return EINVAL;
		}
		uth->uu_flag &= ~UT_ALTSTACK;
		uth->uu_sigstk.ss_flags = ss.ss_flags;
		return 0;
	}
	if (onstack) {
		return EPERM;
	}
/* The older stacksize was 8K, enforce that one so no compat problems */
#define OLDMINSIGSTKSZ 8*1024
	if (ss.ss_size < OLDMINSIGSTKSZ) {
		return ENOMEM;
	}
	uth->uu_flag |= UT_ALTSTACK;
	uth->uu_sigstk = ss;
	return 0;
}

int
kill(proc_t cp, struct kill_args *uap, __unused int32_t *retval)
{
	proc_t p;
	kauth_cred_t uc = kauth_cred_get();
	int posix = uap->posix;         /* !0 if posix behaviour desired */

	AUDIT_ARG(pid, uap->pid);
	AUDIT_ARG(signum, uap->signum);

	if ((u_int)uap->signum >= NSIG) {
		return EINVAL;
	}
	if (uap->pid > 0) {
		/* kill single process */
		if ((p = proc_find(uap->pid)) == NULL) {
			if ((p = pzfind(uap->pid)) != NULL) {
				/*
				 * POSIX 1003.1-2001 requires returning success when killing a
				 * zombie; see Rationale for kill(2).
				 */
				return 0;
			}
			return ESRCH;
		}
		AUDIT_ARG(process, p);
		if (!cansignal(cp, uc, p, uap->signum)) {
			proc_rele(p);
			return EPERM;
		}
		if (uap->signum) {
			psignal(p, uap->signum);
		}
		proc_rele(p);
		return 0;
	}
	switch (uap->pid) {
	case -1: /* broadcast signal */
		return killpg1(cp, uap->signum, 0, 1, posix);
	case 0: /* signal own process group */
		return killpg1(cp, uap->signum, 0, 0, posix);
	default: /* negative explicit process group */
		return killpg1(cp, uap->signum, -(uap->pid), 0, posix);
	}
	/* NOTREACHED */
}

os_reason_t
build_userspace_exit_reason(uint32_t reason_namespace, uint64_t reason_code, user_addr_t payload, uint32_t payload_size,
    user_addr_t reason_string, uint64_t reason_flags)
{
	os_reason_t exit_reason = OS_REASON_NULL;

	int error = 0;
	int num_items_to_copy = 0;
	uint32_t user_data_to_copy = 0;
	char *reason_user_desc = NULL;
	size_t reason_user_desc_len = 0;

	exit_reason = os_reason_create(reason_namespace, reason_code);
	if (exit_reason == OS_REASON_NULL) {
		os_log(OS_LOG_DEFAULT, "build_userspace_exit_reason: failed to allocate exit reason\n");
		return exit_reason;
	}

	exit_reason->osr_flags |= OS_REASON_FLAG_FROM_USERSPACE;

	/*
	 * Only apply flags that are allowed to be passed from userspace.
	 */
	reason_flags = reason_flags & OS_REASON_FLAG_MASK_ALLOWED_FROM_USER;
	exit_reason->osr_flags |= reason_flags;

	if (!(exit_reason->osr_flags & OS_REASON_FLAG_NO_CRASH_REPORT)) {
		exit_reason->osr_flags |= OS_REASON_FLAG_GENERATE_CRASH_REPORT;
	}

	if (payload != USER_ADDR_NULL) {
		if (payload_size == 0) {
			os_log(OS_LOG_DEFAULT, "build_userspace_exit_reason: exit reason with namespace %u,"
			    " nonzero payload but zero length\n", reason_namespace);
			exit_reason->osr_flags |= OS_REASON_FLAG_BAD_PARAMS;
			payload = USER_ADDR_NULL;
		} else {
			num_items_to_copy++;

			if (payload_size > EXIT_REASON_PAYLOAD_MAX_LEN) {
				exit_reason->osr_flags |= OS_REASON_FLAG_PAYLOAD_TRUNCATED;
				payload_size = EXIT_REASON_PAYLOAD_MAX_LEN;
			}

			user_data_to_copy += payload_size;
		}
	}

	if (reason_string != USER_ADDR_NULL) {
		reason_user_desc = (char *)kalloc_data(EXIT_REASON_USER_DESC_MAX_LEN, Z_WAITOK);

		if (reason_user_desc != NULL) {
			error = copyinstr(reason_string, (void *) reason_user_desc,
			    EXIT_REASON_USER_DESC_MAX_LEN, &reason_user_desc_len);

			if (error == 0) {
				num_items_to_copy++;
				user_data_to_copy += reason_user_desc_len;
			} else if (error == ENAMETOOLONG) {
				num_items_to_copy++;
				reason_user_desc[EXIT_REASON_USER_DESC_MAX_LEN - 1] = '\0';
				user_data_to_copy += reason_user_desc_len;
			} else {
				exit_reason->osr_flags |= OS_REASON_FLAG_FAILED_DATA_COPYIN;
				kfree_data(reason_user_desc, EXIT_REASON_USER_DESC_MAX_LEN);
				reason_user_desc = NULL;
				reason_user_desc_len = 0;
			}
		}
	}

	if (num_items_to_copy != 0) {
		uint32_t reason_buffer_size_estimate = 0;
		mach_vm_address_t data_addr = 0;

		reason_buffer_size_estimate = kcdata_estimate_required_buffer_size(num_items_to_copy, user_data_to_copy);

		error = os_reason_alloc_buffer(exit_reason, reason_buffer_size_estimate);
		if (error != 0) {
			os_log(OS_LOG_DEFAULT, "build_userspace_exit_reason: failed to allocate signal reason buffer\n");
			goto out_failed_copyin;
		}

		if (reason_user_desc != NULL && reason_user_desc_len != 0) {
			if (KERN_SUCCESS == kcdata_get_memory_addr(&exit_reason->osr_kcd_descriptor,
			    EXIT_REASON_USER_DESC,
			    (uint32_t)reason_user_desc_len,
			    &data_addr)) {
				kcdata_memcpy(&exit_reason->osr_kcd_descriptor, (mach_vm_address_t) data_addr,
				    reason_user_desc, (uint32_t)reason_user_desc_len);
			} else {
				os_log(OS_LOG_DEFAULT, "build_userspace_exit_reason: failed to allocate space for reason string\n");
				goto out_failed_copyin;
			}
		}

		if (payload != USER_ADDR_NULL) {
			if (KERN_SUCCESS ==
			    kcdata_get_memory_addr(&exit_reason->osr_kcd_descriptor,
			    EXIT_REASON_USER_PAYLOAD,
			    payload_size,
			    &data_addr)) {
				error = copyin(payload, (void *) data_addr, payload_size);
				if (error) {
					os_log(OS_LOG_DEFAULT, "build_userspace_exit_reason: failed to copy in payload data with error %d\n", error);
					goto out_failed_copyin;
				}
			} else {
				os_log(OS_LOG_DEFAULT, "build_userspace_exit_reason: failed to allocate space for payload data\n");
				goto out_failed_copyin;
			}
		}
	}

	if (reason_user_desc != NULL) {
		kfree_data(reason_user_desc, EXIT_REASON_USER_DESC_MAX_LEN);
		reason_user_desc = NULL;
		reason_user_desc_len = 0;
	}

	return exit_reason;

out_failed_copyin:

	if (reason_user_desc != NULL) {
		kfree_data(reason_user_desc, EXIT_REASON_USER_DESC_MAX_LEN);
		reason_user_desc = NULL;
		reason_user_desc_len = 0;
	}

	exit_reason->osr_flags |= OS_REASON_FLAG_FAILED_DATA_COPYIN;
	os_reason_alloc_buffer(exit_reason, 0);
	return exit_reason;
}

static int
terminate_with_payload_internal(struct proc *cur_proc, int target_pid, uint32_t reason_namespace,
    uint64_t reason_code, user_addr_t payload, uint32_t payload_size,
    user_addr_t reason_string, uint64_t reason_flags)
{
	proc_t target_proc = PROC_NULL;
	kauth_cred_t cur_cred = kauth_cred_get();

	os_reason_t signal_reason = OS_REASON_NULL;

	AUDIT_ARG(pid, target_pid);
	if ((target_pid <= 0)) {
		return EINVAL;
	}

	target_proc = proc_find(target_pid);
	if (target_proc == PROC_NULL) {
		return ESRCH;
	}

	AUDIT_ARG(process, target_proc);

	if (!cansignal(cur_proc, cur_cred, target_proc, SIGKILL)) {
		proc_rele(target_proc);
		return EPERM;
	}

	if (target_pid != proc_getpid(cur_proc)) {
		/*
		 * FLAG_ABORT should only be set on terminate_with_reason(getpid()) that
		 * was a fallback from an unsuccessful abort_with_reason(). In that case
		 * caller's pid matches the target one. Otherwise remove the flag.
		 */
		reason_flags &= ~((typeof(reason_flags))OS_REASON_FLAG_ABORT);
	}

	KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_EXITREASON_CREATE) | DBG_FUNC_NONE,
	    proc_getpid(target_proc), reason_namespace,
	    reason_code, 0, 0);

	signal_reason = build_userspace_exit_reason(reason_namespace, reason_code, payload, payload_size,
	    reason_string, (reason_flags | OS_REASON_FLAG_NO_CRASHED_TID));

	if (target_pid == proc_getpid(cur_proc)) {
		/*
		 * psignal_thread_with_reason() will pend a SIGKILL on the specified thread or
		 * return if the thread and/or task are already terminating. Either way, the
		 * current thread won't return to userspace.
		 */
		psignal_thread_with_reason(target_proc, current_thread(), SIGKILL, signal_reason);
	} else {
		psignal_with_reason(target_proc, SIGKILL, signal_reason);
	}

	proc_rele(target_proc);

	return 0;
}

int
terminate_with_payload(struct proc *cur_proc, struct terminate_with_payload_args *args,
    __unused int32_t *retval)
{
	return terminate_with_payload_internal(cur_proc, args->pid, args->reason_namespace, args->reason_code, args->payload,
	           args->payload_size, args->reason_string, args->reason_flags);
}

static int
killpg1_allfilt(proc_t p, void * arg)
{
	struct killpg1_filtargs * kfargp = (struct killpg1_filtargs *)arg;

	/*
	 * Don't signal initproc, a system process, or the current process if POSIX
	 * isn't specified.
	 */
	return proc_getpid(p) > 1 && !(p->p_flag & P_SYSTEM) &&
	       (kfargp->posix ? true : p != kfargp->curproc);
}

static int
killpg1_callback(proc_t p, void *arg)
{
	struct killpg1_iterargs *kargp = (struct killpg1_iterargs *)arg;
	int signum = kargp->signum;

	if (proc_list_exited(p)) {
		/*
		 * Count zombies as found for the purposes of signalling, since POSIX
		 * 1003.1-2001 sees signalling zombies as successful.  If killpg(2) or
		 * kill(2) with pid -1 only finds zombies that can be signalled, it
		 * shouldn't return ESRCH.  See the Rationale for kill(2).
		 *
		 * Don't call into MAC -- it's not expecting signal checks for exited
		 * processes.
		 */
		if (cansignal_nomac(kargp->curproc, kargp->uc, p, signum)) {
			kargp->nfound++;
		}
	} else if (cansignal(kargp->curproc, kargp->uc, p, signum)) {
		kargp->nfound++;

		if (signum != 0) {
			psignal(p, signum);
		}
	}

	return PROC_RETURNED;
}

/*
 * Common code for kill process group/broadcast kill.
 */
int
killpg1(proc_t curproc, int signum, int pgid, int all, int posix)
{
	kauth_cred_t uc;
	struct pgrp *pgrp;
	int error = 0;

	uc = kauth_cred_proc_ref(curproc);
	struct killpg1_iterargs karg = {
		.curproc = curproc, .uc = uc, .nfound = 0, .signum = signum
	};

	if (all) {
		/*
		 * Broadcast to all processes that the user can signal (pid was -1).
		 */
		struct killpg1_filtargs kfarg = {
			.posix = posix, .curproc = curproc
		};
		proc_iterate(PROC_ALLPROCLIST | PROC_ZOMBPROCLIST, killpg1_callback,
		    &karg, killpg1_allfilt, &kfarg);
	} else {
		if (pgid == 0) {
			/*
			 * Send to current the current process' process group.
			 */
			pgrp = proc_pgrp(curproc, NULL);
		} else {
			pgrp = pgrp_find(pgid);
			if (pgrp == NULL) {
				error = ESRCH;
				goto out;
			}
		}

		pgrp_iterate(pgrp, killpg1_callback, &karg, ^bool (proc_t p) {
			if (p == kernproc || p == initproc) {
			        return false;
			}
			/* XXX shouldn't this allow signalling zombies? */
			return !(p->p_flag & P_SYSTEM) && p->p_stat != SZOMB;
		});
		pgrp_rele(pgrp);
	}
	error = (karg.nfound > 0 ? 0 : (posix ? EPERM : ESRCH));
out:
	kauth_cred_unref(&uc);
	return error;
}

/*
 * Send a signal to a process group.
 */
void
gsignal(int pgid, int signum)
{
	struct pgrp *pgrp;

	if (pgid && (pgrp = pgrp_find(pgid))) {
		pgsignal(pgrp, signum, 0);
		pgrp_rele(pgrp);
	}
}

/*
 * Send a signal to a process group.  If checkctty is 1,
 * limit to members which have a controlling terminal.
 */

static int
pgsignal_callback(proc_t p, void * arg)
{
	int  signum = *(int*)arg;

	psignal(p, signum);
	return PROC_RETURNED;
}

void
pgsignal(struct pgrp *pgrp, int signum, int checkctty)
{
	if (pgrp == PGRP_NULL) {
		return;
	}

	bool (^filter)(proc_t) = ^bool (proc_t p) {
		return p->p_flag & P_CONTROLT;
	};

	pgrp_iterate(pgrp, pgsignal_callback, &signum, checkctty ? filter : NULL);
}


void
tty_pgsignal_locked(struct tty *tp, int signum, int checkctty)
{
	struct pgrp * pg;

	pg = tty_pgrp_locked(tp);
	if (pg != PGRP_NULL) {
		tty_unlock(tp);
		pgsignal(pg, signum, checkctty);
		pgrp_rele(pg);
		tty_lock(tp);
	}
}
/*
 * Send a signal caused by a trap to a specific thread.
 */
void
threadsignal(thread_t sig_actthread, int signum, mach_exception_code_t code, boolean_t set_exitreason)
{
	struct uthread *uth;
	struct task * sig_task;
	proc_t p;
	int mask;

	if ((u_int)signum >= NSIG || signum == 0) {
		return;
	}

	mask = sigmask(signum);
	if ((mask & threadmask) == 0) {
		return;
	}
	sig_task = get_threadtask(sig_actthread);
	p = (proc_t)(get_bsdtask_info(sig_task));

	uth = get_bsdthread_info(sig_actthread);

	proc_lock(p);
	if (!(p->p_lflag & P_LTRACED) && (p->p_sigignore & mask)) {
		proc_unlock(p);
		return;
	}

	uth->uu_siglist |= mask;
	uth->uu_code = code;

	/* Attempt to establish whether the signal will be fatal (mirrors logic in psignal_internal()) */
	if (set_exitreason && ((p->p_lflag & P_LTRACED) || (!(uth->uu_sigwait & mask)
	    && !(uth->uu_sigmask & mask) && !(p->p_sigcatch & mask))) &&
	    !(mask & stopsigmask) && !(mask & contsigmask)) {
		if (uth->uu_exit_reason == OS_REASON_NULL) {
			KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_EXITREASON_CREATE) | DBG_FUNC_NONE,
			    proc_getpid(p), OS_REASON_SIGNAL, signum, 0, 0);

			os_reason_t signal_reason = build_signal_reason(signum, "exc handler");

			set_thread_exit_reason(sig_actthread, signal_reason, TRUE);

			/* We dropped/consumed the reference in set_thread_exit_reason() */
			signal_reason = OS_REASON_NULL;
		}
	}

	proc_unlock(p);

	/* mark on process as well */
	signal_setast(sig_actthread);
}

/* Called with proc locked */
static void
set_thread_extra_flags(task_t task, struct uthread *uth, os_reason_t reason)
{
	extern int vm_shared_region_reslide_restrict;
	boolean_t reslide_shared_region = FALSE;
	boolean_t driver = task_is_driver(task);
	assert(uth != NULL);
	/*
	 * Check whether the userland fault address falls within the shared
	 * region and notify userland if so. To limit the occurrences of shared
	 * cache resliding - and its associated memory tax - only investigate the
	 * fault if it is consequence of accessing unmapped memory (SIGSEGV) or
	 * accessing with incorrect permissions (SIGBUS - KERN_PROTECTION_FAILURE).
	 *
	 * This allows launchd to apply special policies around this fault type.
	 */
	if (reason->osr_namespace == OS_REASON_SIGNAL &&
	    (reason->osr_code == SIGSEGV ||
	    (reason->osr_code == SIGBUS && uth->uu_code == KERN_PROTECTION_FAILURE))) {
		mach_vm_address_t fault_address = uth->uu_subcode;

		/* Address is in userland, so we hard clear any non-canonical bits to 0 here */
		fault_address = VM_USER_STRIP_PTR(fault_address);

		if (fault_address >= SHARED_REGION_BASE &&
		    fault_address <= SHARED_REGION_BASE + SHARED_REGION_SIZE) {
			/*
			 * Always report whether the fault happened within the shared cache
			 * region, but only stale the slide if the resliding is extended
			 * to all processes or if the process faulting is a platform one.
			 */
			reason->osr_flags |= OS_REASON_FLAG_SHAREDREGION_FAULT;

#if __has_feature(ptrauth_calls)
			if (!vm_shared_region_reslide_restrict || csproc_get_platform_binary(current_proc())) {
				reslide_shared_region = TRUE;
			}
#endif /* __has_feature(ptrauth_calls) */
		}

		if (driver) {
			/*
			 * Always reslide the DriverKit shared region if the driver faulted.
			 * The memory cost is acceptable because the DriverKit shared cache is small
			 * and there are relatively few driver processes.
			 */
			reslide_shared_region = TRUE;
		}
	}

	if (reslide_shared_region) {
		vm_shared_region_reslide_stale(driver);
	}
}

void
set_thread_exit_reason(void *th, void *reason, boolean_t proc_locked)
{
	struct uthread *targ_uth = get_bsdthread_info(th);
	struct task *targ_task = get_threadtask(th);
	proc_t targ_proc = NULL;

	os_reason_t exit_reason = (os_reason_t)reason;

	if (exit_reason == OS_REASON_NULL) {
		return;
	}

	if (!proc_locked) {
		targ_proc = (proc_t)(get_bsdtask_info(targ_task));

		proc_lock(targ_proc);
	}

	set_thread_extra_flags(targ_task, targ_uth, exit_reason);

	if (targ_uth->uu_exit_reason == OS_REASON_NULL) {
		targ_uth->uu_exit_reason = exit_reason;
	} else {
		/* The caller expects that we drop a reference on the exit reason */
		os_reason_free(exit_reason);
	}

	if (!proc_locked) {
		assert(targ_proc != NULL);
		proc_unlock(targ_proc);
	}
}

/*
 * get_signalthread
 *
 * Picks an appropriate thread from a process to target with a signal.
 *
 * Called with proc locked.
 * Returns thread with BSD ast set.
 *
 * We attempt to deliver a proc-wide signal to the first thread in the task.
 * This allows single threaded applications which use signals to
 * be able to be linked with multithreaded libraries.
 */
static kern_return_t
get_signalthread(proc_t p, int signum, thread_t * thr)
{
	struct uthread *uth;
	sigset_t mask = sigmask(signum);
	bool skip_wqthreads = true;

	*thr = THREAD_NULL;


again:
	TAILQ_FOREACH(uth, &p->p_uthlist, uu_list) {
		if (((uth->uu_flag & UT_NO_SIGMASK) == 0) &&
		    (((uth->uu_sigmask & mask) == 0) || (uth->uu_sigwait & mask))) {
			thread_t th = get_machthread(uth);
			if (skip_wqthreads && (thread_get_tag(th) & THREAD_TAG_WORKQUEUE)) {
				/* Workqueue threads may be parked in the kernel unable to
				 * deliver signals for an extended period of time, so skip them
				 * in favor of pthreads in a first pass. (rdar://50054475). */
			} else if (check_actforsig(proc_task(p), th, 1) == KERN_SUCCESS) {
				*thr = th;
				return KERN_SUCCESS;
			}
		}
	}
	if (skip_wqthreads) {
		skip_wqthreads = false;
		goto again;
	}
	if (get_signalact(proc_task(p), thr, 1) == KERN_SUCCESS) {
		return KERN_SUCCESS;
	}

	return KERN_FAILURE;
}

static os_reason_t
build_signal_reason(int signum, const char *procname)
{
	os_reason_t signal_reason = OS_REASON_NULL;
	proc_t sender_proc = current_proc();
	uint32_t reason_buffer_size_estimate = 0, proc_name_length = 0;
	const char *default_sender_procname = "unknown";
	mach_vm_address_t data_addr;
	int ret;

	signal_reason = os_reason_create(OS_REASON_SIGNAL, signum);
	if (signal_reason == OS_REASON_NULL) {
		printf("build_signal_reason: unable to allocate signal reason structure.\n");
		return signal_reason;
	}

	reason_buffer_size_estimate = kcdata_estimate_required_buffer_size(2, sizeof(sender_proc->p_name) +
	    sizeof(pid_t));

	ret = os_reason_alloc_buffer_noblock(signal_reason, reason_buffer_size_estimate);
	if (ret != 0) {
		printf("build_signal_reason: unable to allocate signal reason buffer.\n");
		return signal_reason;
	}

	if (KERN_SUCCESS == kcdata_get_memory_addr(&signal_reason->osr_kcd_descriptor, KCDATA_TYPE_PID,
	    sizeof(pid_t), &data_addr)) {
		pid_t pid = proc_getpid(sender_proc);
		kcdata_memcpy(&signal_reason->osr_kcd_descriptor, data_addr, &pid, sizeof(pid));
	} else {
		printf("build_signal_reason: exceeded space in signal reason buf, unable to log PID\n");
	}

	proc_name_length = sizeof(sender_proc->p_name);
	if (KERN_SUCCESS == kcdata_get_memory_addr(&signal_reason->osr_kcd_descriptor, KCDATA_TYPE_PROCNAME,
	    proc_name_length, &data_addr)) {
		if (procname) {
			char truncated_procname[proc_name_length];
			strncpy((char *) &truncated_procname, procname, proc_name_length);
			truncated_procname[proc_name_length - 1] = '\0';

			kcdata_memcpy(&signal_reason->osr_kcd_descriptor, data_addr, truncated_procname,
			    (uint32_t)strlen((char *) &truncated_procname));
		} else if (*sender_proc->p_name) {
			kcdata_memcpy(&signal_reason->osr_kcd_descriptor, data_addr, &sender_proc->p_name,
			    sizeof(sender_proc->p_name));
		} else {
			kcdata_memcpy(&signal_reason->osr_kcd_descriptor, data_addr, &default_sender_procname,
			    (uint32_t)strlen(default_sender_procname) + 1);
		}
	} else {
		printf("build_signal_reason: exceeded space in signal reason buf, unable to log procname\n");
	}

	return signal_reason;
}

/*
 * Send the signal to the process.  If the signal has an action, the action
 * is usually performed by the target process rather than the caller; we add
 * the signal to the set of pending signals for the process.
 *
 * Always drops a reference on a signal_reason if one is provided, whether via
 * passing it to a thread or deallocating directly.
 *
 * Exceptions:
 *   o When a stop signal is sent to a sleeping process that takes the
 *     default action, the process is stopped without awakening it.
 *   o SIGCONT restarts stopped processes (or puts them back to sleep)
 *     regardless of the signal action (eg, blocked or ignored).
 *
 * Other ignored signals are discarded immediately.
 */
static void
psignal_internal(proc_t p, task_t task, thread_t thread, int flavor, int signum, os_reason_t signal_reason)
{
	int prop;
	user_addr_t action = USER_ADDR_NULL;
	proc_t                  sig_proc;
	thread_t                sig_thread;
	task_t                  sig_task;
	int                     mask;
	struct uthread          *uth;
	kern_return_t           kret;
	uid_t                   r_uid;
	proc_t                  pp;
	kauth_cred_t            my_cred;
	char                    *launchd_exit_reason_desc = NULL;
	boolean_t               update_thread_policy = FALSE;

	if ((u_int)signum >= NSIG || signum == 0) {
		panic("psignal: bad signal number %d", signum);
	}

	mask = sigmask(signum);
	prop = sigprop[signum];

#if SIGNAL_DEBUG
	if (rdebug_proc && (p != PROC_NULL) && (p == rdebug_proc)) {
		ram_printf(3);
	}
#endif /* SIGNAL_DEBUG */

	/* catch unexpected initproc kills early for easier debuggging */
	if (signum == SIGKILL && p == initproc) {
		if (signal_reason == NULL) {
			panic_plain("unexpected SIGKILL of %s %s (no reason provided)",
			    (p->p_name[0] != '\0' ? p->p_name : "initproc"),
			    ((proc_getcsflags(p) & CS_KILLED) ? "(CS_KILLED)" : ""));
		} else {
			launchd_exit_reason_desc = exit_reason_get_string_desc(signal_reason);
			panic_plain("unexpected SIGKILL of %s %s with reason -- namespace %d code 0x%llx description %." LAUNCHD_PANIC_REASON_STRING_MAXLEN "s",
			    (p->p_name[0] != '\0' ? p->p_name : "initproc"),
			    ((proc_getcsflags(p) & CS_KILLED) ? "(CS_KILLED)" : ""),
			    signal_reason->osr_namespace, signal_reason->osr_code,
			    launchd_exit_reason_desc ? launchd_exit_reason_desc : "none");
		}
	}

	/*
	 *	We will need the task pointer later.  Grab it now to
	 *	check for a zombie process.  Also don't send signals
	 *	to kernel internal tasks.
	 */
	if (flavor & PSIG_VFORK) {
		sig_task = task;
		sig_thread = thread;
		sig_proc = p;
	} else if (flavor & PSIG_THREAD) {
		sig_task = get_threadtask(thread);
		sig_thread = thread;
		sig_proc = (proc_t)get_bsdtask_info(sig_task);
	} else if (flavor & PSIG_TRY_THREAD) {
		assert((thread == current_thread()) && (p == current_proc()));
		sig_task = proc_task(p);
		sig_thread = thread;
		sig_proc = p;
	} else {
		sig_task = proc_task(p);
		sig_thread = THREAD_NULL;
		sig_proc = p;
	}

	if ((sig_task == TASK_NULL) || is_kerneltask(sig_task)) {
		os_reason_free(signal_reason);
		return;
	}

	if ((flavor & (PSIG_VFORK | PSIG_THREAD)) == 0) {
		proc_knote(sig_proc, NOTE_SIGNAL | signum);
	}

	if ((flavor & PSIG_LOCKED) == 0) {
		proc_signalstart(sig_proc, 0);
	}

	/* Don't send signals to a process that has ignored them. */
	if (((flavor & PSIG_VFORK) == 0) && ((sig_proc->p_lflag & P_LTRACED) == 0) && (sig_proc->p_sigignore & mask)) {
		DTRACE_PROC3(signal__discard, thread_t, sig_thread, proc_t, sig_proc, int, signum);
		goto sigout_unlocked;
	}

	/*
	 * The proc_lock prevents the targeted thread from being deallocated
	 * or handling the signal until we're done signaling it.
	 *
	 * Once the proc_lock is dropped, we have no guarantee the thread or uthread exists anymore.
	 *
	 * XXX: What if the thread goes inactive after the thread passes bsd ast point?
	 */
	proc_lock(sig_proc);

	/*
	 * Don't send signals to a process which has already exited and thus
	 * committed to a particular p_xstat exit code.
	 * Additionally, don't abort the process running 'reboot'.
	 */
	if (ISSET(sig_proc->p_flag, P_REBOOT) || ISSET(sig_proc->p_lflag, P_LEXIT)) {
		DTRACE_PROC3(signal__discard, thread_t, sig_thread, proc_t, sig_proc, int, signum);
		goto sigout_locked;
	}

	if (flavor & PSIG_VFORK) {
		action = SIG_DFL;
		act_set_astbsd(sig_thread);
		kret = KERN_SUCCESS;
	} else if (flavor & PSIG_TRY_THREAD) {
		uth = get_bsdthread_info(sig_thread);
		if (((uth->uu_flag & UT_NO_SIGMASK) == 0) &&
		    (((uth->uu_sigmask & mask) == 0) || (uth->uu_sigwait & mask)) &&
		    ((kret = check_actforsig(proc_task(sig_proc), sig_thread, 1)) == KERN_SUCCESS)) {
			/* deliver to specified thread */
		} else {
			/* deliver to any willing thread */
			kret = get_signalthread(sig_proc, signum, &sig_thread);
		}
	} else if (flavor & PSIG_THREAD) {
		/* If successful return with ast set */
		kret = check_actforsig(sig_task, sig_thread, 1);
	} else {
		/* If successful return with ast set */
		kret = get_signalthread(sig_proc, signum, &sig_thread);
	}

	if (kret != KERN_SUCCESS) {
		DTRACE_PROC3(signal__discard, thread_t, sig_thread, proc_t, sig_proc, int, signum);
		proc_unlock(sig_proc);
		goto sigout_unlocked;
	}

	uth = get_bsdthread_info(sig_thread);

	/*
	 * If proc is traced, always give parent a chance.
	 */

	if ((flavor & PSIG_VFORK) == 0) {
		if (sig_proc->p_lflag & P_LTRACED) {
			action = SIG_DFL;
		} else {
			/*
			 * If the signal is being ignored,
			 * then we forget about it immediately.
			 * (Note: we don't set SIGCONT in p_sigignore,
			 * and if it is set to SIG_IGN,
			 * action will be SIG_DFL here.)
			 */
			if (sig_proc->p_sigignore & mask) {
				goto sigout_locked;
			}

			if (uth->uu_sigwait & mask) {
				action = KERN_SIG_WAIT;
			} else if (uth->uu_sigmask & mask) {
				action = KERN_SIG_HOLD;
			} else if (sig_proc->p_sigcatch & mask) {
				action = KERN_SIG_CATCH;
			} else {
				action = SIG_DFL;
			}
		}
	}

	/* TODO: p_nice isn't hooked up to the scheduler... */
	if (sig_proc->p_nice > NZERO && action == SIG_DFL && (prop & SA_KILL) &&
	    (sig_proc->p_lflag & P_LTRACED) == 0) {
		sig_proc->p_nice = NZERO;
	}

	if (prop & SA_CONT) {
		uth->uu_siglist &= ~stopsigmask;
	}

	if (prop & SA_STOP) {
		struct pgrp *pg;
		/*
		 * If sending a tty stop signal to a member of an orphaned
		 * process group, discard the signal here if the action
		 * is default; don't stop the process below if sleeping,
		 * and don't clear any pending SIGCONT.
		 */
		pg = proc_pgrp(sig_proc, NULL);
		if (prop & SA_TTYSTOP && pg->pg_jobc == 0 &&
		    action == SIG_DFL) {
			pgrp_rele(pg);
			goto sigout_locked;
		}
		pgrp_rele(pg);
		uth->uu_siglist &= ~contsigmask;
	}

	uth->uu_siglist |= mask;

	/*
	 * Defer further processing for signals which are held,
	 * except that stopped processes must be continued by SIGCONT.
	 */
	if ((action == KERN_SIG_HOLD) && ((prop & SA_CONT) == 0 || sig_proc->p_stat != SSTOP)) {
		goto sigout_locked;
	}

	/*
	 *	SIGKILL priority twiddling moved here from above because
	 *	it needs sig_thread.  Could merge it into large switch
	 *	below if we didn't care about priority for tracing
	 *	as SIGKILL's action is always SIG_DFL.
	 *
	 *	TODO: p_nice isn't hooked up to the scheduler...
	 */
	if ((signum == SIGKILL) && (sig_proc->p_nice > NZERO)) {
		sig_proc->p_nice = NZERO;
	}

	/*
	 *	Process is traced - wake it up (if not already
	 *	stopped) so that it can discover the signal in
	 *	issig() and stop for the parent.
	 */
	if (sig_proc->p_lflag & P_LTRACED) {
		if (sig_proc->p_stat != SSTOP) {
			goto runlocked;
		} else {
			goto sigout_locked;
		}
	}

	if ((flavor & PSIG_VFORK) != 0) {
		goto runlocked;
	}

	if (action == KERN_SIG_WAIT) {
#if CONFIG_DTRACE
		/*
		 * DTrace proc signal-clear returns a siginfo_t. Collect the needed info.
		 */
		r_uid = kauth_getruid(); /* per thread credential; protected by our thread context */

		bzero((caddr_t)&(uth->t_dtrace_siginfo), sizeof(uth->t_dtrace_siginfo));

		uth->t_dtrace_siginfo.si_signo = signum;
		uth->t_dtrace_siginfo.si_pid = proc_getpid(current_proc());
		uth->t_dtrace_siginfo.si_status = W_EXITCODE(signum, 0);
		uth->t_dtrace_siginfo.si_uid = r_uid;
		uth->t_dtrace_siginfo.si_code = 0;
#endif
		uth->uu_sigwait = mask;
		uth->uu_siglist &= ~mask;
		wakeup(&uth->uu_sigwait);
		/* if it is SIGCONT resume whole process */
		if (prop & SA_CONT) {
			OSBitOrAtomic(P_CONTINUED, &sig_proc->p_flag);
			sig_proc->p_contproc = proc_getpid(current_proc());
			(void) task_resume_internal(sig_task);
		}
		goto sigout_locked;
	}

	if (action != SIG_DFL) {
		/*
		 *	User wants to catch the signal.
		 *	Wake up the thread, but don't un-suspend it
		 *	(except for SIGCONT).
		 */
		if (prop & SA_CONT) {
			OSBitOrAtomic(P_CONTINUED, &sig_proc->p_flag);
			(void) task_resume_internal(sig_task);
			sig_proc->p_stat = SRUN;
		} else if (sig_proc->p_stat == SSTOP) {
			goto sigout_locked;
		}
		/*
		 * Fill out siginfo structure information to pass to the
		 * signalled process/thread sigaction handler, when it
		 * wakes up.  si_code is 0 because this is an ordinary
		 * signal, not a SIGCHLD, and so si_status is the signal
		 * number itself, instead of the child process exit status.
		 * We shift this left because it will be shifted right before
		 * it is passed to user space.  kind of ugly to use W_EXITCODE
		 * this way, but it beats defining a new macro.
		 *
		 * Note:	Avoid the SIGCHLD recursion case!
		 */
		if (signum != SIGCHLD) {
			r_uid = kauth_getruid();

			sig_proc->si_pid = proc_getpid(current_proc());
			sig_proc->si_status = W_EXITCODE(signum, 0);
			sig_proc->si_uid = r_uid;
			sig_proc->si_code = 0;
		}

		goto runlocked;
	} else {
		/*	Default action - varies */
		if (mask & stopsigmask) {
			assert(signal_reason == NULL);
			/*
			 * These are the signals which by default
			 * stop a process.
			 *
			 * Don't clog system with children of init
			 * stopped from the keyboard.
			 */
			if (!(prop & SA_STOP) && sig_proc->p_pptr == initproc) {
				uth->uu_siglist &= ~mask;
				proc_unlock(sig_proc);
				/* siglock still locked, proc_lock not locked */
				psignal_locked(sig_proc, SIGKILL);
				goto sigout_unlocked;
			}

			/*
			 *	Stop the task
			 *	if task hasn't already been stopped by
			 *	a signal.
			 */
			uth->uu_siglist &= ~mask;
			if (sig_proc->p_stat != SSTOP) {
				sig_proc->p_xstat = signum;
				sig_proc->p_stat = SSTOP;
				OSBitAndAtomic(~((uint32_t)P_CONTINUED), &sig_proc->p_flag);
				sig_proc->p_lflag &= ~P_LWAITED;
				proc_signalend(sig_proc, 1);
				proc_unlock(sig_proc);

				pp = proc_parentholdref(sig_proc);
				proc_signalstart(sig_proc, 0);
				stop(sig_proc, pp);
				if ((pp != PROC_NULL) && ((pp->p_flag & P_NOCLDSTOP) == 0)) {
					my_cred = kauth_cred_proc_ref(sig_proc);
					r_uid = kauth_cred_getruid(my_cred);
					kauth_cred_unref(&my_cred);

					proc_lock(sig_proc);
					pp->si_pid = proc_getpid(sig_proc);
					/*
					 * POSIX: sigaction for a stopped child
					 * when sent to the parent must set the
					 * child's signal number into si_status.
					 */
					if (signum != SIGSTOP) {
						pp->si_status = WEXITSTATUS(sig_proc->p_xstat);
					} else {
						pp->si_status = W_EXITCODE(signum, signum);
					}
					pp->si_code = CLD_STOPPED;
					pp->si_uid = r_uid;
					proc_unlock(sig_proc);

					psignal(pp, SIGCHLD);
				}
				if (pp != PROC_NULL) {
					proc_parentdropref(pp, 0);
				}

				goto sigout_unlocked;
			}

			goto sigout_locked;
		}

		DTRACE_PROC3(signal__send, thread_t, sig_thread, proc_t, p, int, signum);

		switch (signum) {
		/*
		 * Signals ignored by default have been dealt
		 * with already, since their bits are on in
		 * p_sigignore.
		 */

		case SIGKILL:
			/*
			 * Kill signal always sets process running and
			 * unsuspends it.
			 */
			/*
			 *	Process will be running after 'run'
			 */
			sig_proc->p_stat = SRUN;
			/*
			 * In scenarios where suspend/resume are racing
			 * the signal we are missing AST_BSD by the time
			 * we get here, set again to avoid races. This
			 * was the scenario with spindump enabled shutdowns.
			 * We would need to cover this approp down the line.
			 */
			act_set_astbsd(sig_thread);
			kret = thread_abort(sig_thread);
			update_thread_policy = (kret == KERN_SUCCESS);

			if (uth->uu_exit_reason == OS_REASON_NULL) {
				if (signal_reason == OS_REASON_NULL) {
					KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_EXITREASON_CREATE) | DBG_FUNC_NONE,
					    proc_getpid(sig_proc), OS_REASON_SIGNAL, signum, 0, 0);

					signal_reason = build_signal_reason(signum, NULL);
				}

				os_reason_ref(signal_reason);
				set_thread_exit_reason(sig_thread, signal_reason, TRUE);
			}

			goto sigout_locked;

		case SIGCONT:
			/*
			 * Let the process run.  If it's sleeping on an
			 * event, it remains so.
			 */
			assert(signal_reason == NULL);
			OSBitOrAtomic(P_CONTINUED, &sig_proc->p_flag);
			sig_proc->p_contproc = proc_getpid(sig_proc);
			sig_proc->p_xstat = signum;

			(void) task_resume_internal(sig_task);

			/*
			 * When processing a SIGCONT, we need to check
			 * to see if there are signals pending that
			 * were not delivered because we had been
			 * previously stopped.  If that's the case,
			 * we need to thread_abort_safely() to trigger
			 * interruption of the current system call to
			 * cause their handlers to fire.  If it's only
			 * the SIGCONT, then don't wake up.
			 */
			if (((flavor & (PSIG_VFORK | PSIG_THREAD)) == 0) && (((uth->uu_siglist & ~uth->uu_sigmask) & ~sig_proc->p_sigignore) & ~mask)) {
				uth->uu_siglist &= ~mask;
				sig_proc->p_stat = SRUN;
				goto runlocked;
			}

			uth->uu_siglist &= ~mask;
			sig_proc->p_stat = SRUN;
			goto sigout_locked;

		default:
		{
			/*
			 * A signal which has a default action of killing
			 * the process, and for which there is no handler,
			 * needs to act like SIGKILL
			 *
			 * The thread_sstop condition is a remnant of a fix
			 * where PSIG_THREAD exit reasons were not set
			 * correctly (93593933). We keep the behavior with
			 * SSTOP the same as before.
			 */
			const bool default_kill = (action == SIG_DFL) && (prop & SA_KILL);
			const bool thread_sstop = (flavor & PSIG_THREAD) && (sig_proc->p_stat == SSTOP);

			if (default_kill && !thread_sstop) {
				sig_proc->p_stat = SRUN;
				kret = thread_abort(sig_thread);
				update_thread_policy = (kret == KERN_SUCCESS);

				if (uth->uu_exit_reason == OS_REASON_NULL) {
					if (signal_reason == OS_REASON_NULL) {
						KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_EXITREASON_CREATE) | DBG_FUNC_NONE,
						    proc_getpid(sig_proc), OS_REASON_SIGNAL, signum, 0, 0);

						signal_reason = build_signal_reason(signum, NULL);
					}

					os_reason_ref(signal_reason);
					set_thread_exit_reason(sig_thread, signal_reason, TRUE);
				}

				goto sigout_locked;
			}

			/*
			 * All other signals wake up the process, but don't
			 * resume it.
			 */
			if (sig_proc->p_stat == SSTOP) {
				goto sigout_locked;
			}
			goto runlocked;
		}
		}
	}
	/*NOTREACHED*/

runlocked:
	/*
	 * If we're being traced (possibly because someone attached us
	 * while we were stopped), check for a signal from the debugger.
	 */
	if (sig_proc->p_stat == SSTOP) {
		if ((sig_proc->p_lflag & P_LTRACED) != 0 && sig_proc->p_xstat != 0) {
			uth->uu_siglist |= sigmask(sig_proc->p_xstat);
		}

		if ((flavor & PSIG_VFORK) != 0) {
			sig_proc->p_stat = SRUN;
		}
	} else {
		/*
		 * setrunnable(p) in BSD and
		 * Wake up the thread if it is interruptible.
		 */
		sig_proc->p_stat = SRUN;
		if ((flavor & PSIG_VFORK) == 0) {
			thread_abort_safely(sig_thread);
		}
	}

sigout_locked:
	if (update_thread_policy) {
		/*
		 * Update the thread policy to heading to terminate, increase priority if
		 * necessary. This needs to be done before we drop the proc lock because the
		 * thread can take the fatal signal once it's dropped.
		 */
		proc_set_thread_policy(sig_thread, TASK_POLICY_ATTRIBUTE, TASK_POLICY_TERMINATED, TASK_POLICY_ENABLE);
	}

	proc_unlock(sig_proc);

sigout_unlocked:
	os_reason_free(signal_reason);
	if ((flavor & PSIG_LOCKED) == 0) {
		proc_signalend(sig_proc, 0);
	}
}

void
psignal(proc_t p, int signum)
{
	psignal_internal(p, NULL, NULL, 0, signum, NULL);
}

void
psignal_with_reason(proc_t p, int signum, struct os_reason *signal_reason)
{
	psignal_internal(p, NULL, NULL, 0, signum, signal_reason);
}

void
psignal_sigkill_with_reason(struct proc *p, struct os_reason *signal_reason)
{
	psignal_internal(p, NULL, NULL, 0, SIGKILL, signal_reason);
}

void
psignal_locked(proc_t p, int signum)
{
	psignal_internal(p, NULL, NULL, PSIG_LOCKED, signum, NULL);
}

void
psignal_vfork_with_reason(proc_t p, task_t new_task, thread_t thread, int signum, struct os_reason *signal_reason)
{
	psignal_internal(p, new_task, thread, PSIG_VFORK, signum, signal_reason);
}

void
psignal_vfork(proc_t p, task_t new_task, thread_t thread, int signum)
{
	psignal_internal(p, new_task, thread, PSIG_VFORK, signum, NULL);
}

void
psignal_uthread(thread_t thread, int signum)
{
	psignal_internal(PROC_NULL, TASK_NULL, thread, PSIG_THREAD, signum, NULL);
}

/* same as psignal(), but prefer delivery to 'thread' if possible */
void
psignal_try_thread(proc_t p, thread_t thread, int signum)
{
	psignal_internal(p, NULL, thread, PSIG_TRY_THREAD, signum, NULL);
}

void
psignal_try_thread_with_reason(proc_t p, thread_t thread, int signum, struct os_reason *signal_reason)
{
	psignal_internal(p, TASK_NULL, thread, PSIG_TRY_THREAD, signum, signal_reason);
}

void
psignal_thread_with_reason(proc_t p, thread_t thread, int signum, struct os_reason *signal_reason)
{
	psignal_internal(p, TASK_NULL, thread, PSIG_THREAD, signum, signal_reason);
}

/*
 * If the current process has received a signal (should be caught or cause
 * termination, should interrupt current syscall), return the signal number.
 * Stop signals with default action are processed immediately, then cleared;
 * they aren't returned.  This is checked after each entry to the system for
 * a syscall or trap (though this can usually be done without calling issignal
 * by checking the pending signal masks in the CURSIG macro.) The normal call
 * sequence is
 *
 *	while (signum = CURSIG(curproc))
 *		postsig(signum);
 */
int
issignal_locked(proc_t p)
{
	int signum, mask, prop, sigbits;
	thread_t cur_act;
	struct uthread * ut;
	proc_t pp;
	kauth_cred_t my_cred;
	int retval = 0;
	uid_t r_uid;

	cur_act = current_thread();

#if SIGNAL_DEBUG
	if (rdebug_proc && (p == rdebug_proc)) {
		ram_printf(3);
	}
#endif /* SIGNAL_DEBUG */

	/*
	 * Try to grab the signal lock.
	 */
	if (sig_try_locked(p) <= 0) {
		return 0;
	}

	proc_signalstart(p, 1);

	ut = get_bsdthread_info(cur_act);
	for (;;) {
		sigbits = ut->uu_siglist & ~ut->uu_sigmask;

		if (p->p_lflag & P_LPPWAIT) {
			sigbits &= ~stopsigmask;
		}
		if (sigbits == 0) {             /* no signal to send */
			retval = 0;
			goto out;
		}

		signum = ffs((unsigned int)sigbits);
		mask = sigmask(signum);
		prop = sigprop[signum];

		/*
		 * We should see pending but ignored signals
		 * only if P_LTRACED was on when they were posted.
		 */
		if (mask & p->p_sigignore && (p->p_lflag & P_LTRACED) == 0) {
			ut->uu_siglist &= ~mask;
			continue;
		}

		if (p->p_lflag & P_LTRACED && (p->p_lflag & P_LPPWAIT) == 0) {
			/*
			 * If traced, deliver the signal to the debugger, and wait to be
			 * released.
			 */
			task_t  task;
			p->p_xstat = signum;

			if (p->p_lflag & P_LSIGEXC) {
				p->sigwait = TRUE;
				p->sigwait_thread = cur_act;
				p->p_stat = SSTOP;
				OSBitAndAtomic(~((uint32_t)P_CONTINUED), &p->p_flag);
				p->p_lflag &= ~P_LWAITED;
				ut->uu_siglist &= ~mask; /* clear the current signal from the pending list */
				proc_signalend(p, 1);
				proc_unlock(p);
				do_bsdexception(EXC_SOFTWARE, EXC_SOFT_SIGNAL, signum);
				proc_lock(p);
				proc_signalstart(p, 1);
			} else {
				proc_unlock(p);
				my_cred = kauth_cred_proc_ref(p);
				r_uid = kauth_cred_getruid(my_cred);
				kauth_cred_unref(&my_cred);

				/*
				 *	XXX Have to really stop for debuggers;
				 *	XXX stop() doesn't do the right thing.
				 */
				task = proc_task(p);
				task_suspend_internal(task);

				proc_lock(p);
				p->sigwait = TRUE;
				p->sigwait_thread = cur_act;
				p->p_stat = SSTOP;
				OSBitAndAtomic(~((uint32_t)P_CONTINUED), &p->p_flag);
				p->p_lflag &= ~P_LWAITED;
				ut->uu_siglist &= ~mask;

				proc_signalend(p, 1);
				proc_unlock(p);

				pp = proc_parentholdref(p);
				if (pp != PROC_NULL) {
					proc_lock(pp);
					pp->si_pid = proc_getpid(p);
					pp->p_xhighbits = p->p_xhighbits;
					p->p_xhighbits = 0;
					pp->si_status = p->p_xstat;
					pp->si_code = CLD_TRAPPED;
					pp->si_uid = r_uid;
					proc_unlock(pp);

					psignal(pp, SIGCHLD);
					proc_list_lock();
					wakeup((caddr_t)pp);
					proc_parentdropref(pp, 1);
					proc_list_unlock();
				}

				assert_wait((caddr_t)&p->sigwait, (THREAD_INTERRUPTIBLE));
				thread_block(THREAD_CONTINUE_NULL);
				proc_lock(p);
				proc_signalstart(p, 1);
			}

			p->sigwait = FALSE;
			p->sigwait_thread = NULL;
			wakeup((caddr_t)&p->sigwait_thread);

			if (signum == SIGKILL || ut->uu_siglist & sigmask(SIGKILL)) {
				/*
				 * Deliver a pending sigkill even if it's not the current signal.
				 * Necessary for PT_KILL, which should not be delivered to the
				 * debugger, but we can't differentiate it from any other KILL.
				 */
				signum = SIGKILL;
				goto deliver_sig;
			}

			/* We may have to quit. */
			if (thread_should_abort(current_thread())) {
				retval = 0;
				goto out;
			}

			/*
			 * If parent wants us to take the signal,
			 * then it will leave it in p->p_xstat;
			 * otherwise we just look for signals again.
			 */
			signum = p->p_xstat;
			if (signum == 0) {
				continue;
			}

			/*
			 * Put the new signal into p_siglist.  If the
			 * signal is being masked, look for other signals.
			 */
			mask = sigmask(signum);
			ut->uu_siglist |= mask;
			if (ut->uu_sigmask & mask) {
				continue;
			}
		}

		/*
		 * Decide whether the signal should be returned.
		 * Return the signal's number, or fall through
		 * to clear it from the pending mask.
		 */

		switch ((long)SIGACTION(p, signum)) {
		case (long)SIG_DFL:
			/*
			 * If there is a pending stop signal to process
			 * with default action, stop here,
			 * then clear the signal.  However,
			 * if process is member of an orphaned
			 * process group, ignore tty stop signals.
			 */
			if (prop & SA_STOP) {
				struct pgrp * pg;

				proc_unlock(p);
				pg = proc_pgrp(p, NULL);
				if (p->p_lflag & P_LTRACED ||
				    (pg->pg_jobc == 0 &&
				    prop & SA_TTYSTOP)) {
					proc_lock(p);
					pgrp_rele(pg);
					break; /* ignore signal */
				}
				pgrp_rele(pg);
				if (p->p_stat != SSTOP) {
					proc_lock(p);
					p->p_xstat = signum;
					p->p_stat = SSTOP;
					p->p_lflag &= ~P_LWAITED;
					proc_signalend(p, 1);
					proc_unlock(p);

					pp = proc_parentholdref(p);
					proc_signalstart(p, 0);
					stop(p, pp);
					if ((pp != PROC_NULL) && ((pp->p_flag & P_NOCLDSTOP) == 0)) {
						my_cred = kauth_cred_proc_ref(p);
						r_uid = kauth_cred_getruid(my_cred);
						kauth_cred_unref(&my_cred);

						proc_lock(pp);
						pp->si_pid = proc_getpid(p);
						pp->si_status = WEXITSTATUS(p->p_xstat);
						pp->si_code = CLD_STOPPED;
						pp->si_uid = r_uid;
						proc_unlock(pp);

						psignal(pp, SIGCHLD);
					}
					if (pp != PROC_NULL) {
						proc_parentdropref(pp, 0);
					}
				}
				proc_lock(p);
				break;
			} else if (prop & SA_IGNORE) {
				/*
				 * Except for SIGCONT, shouldn't get here.
				 * Default action is to ignore; drop it.
				 */
				break; /* ignore signal */
			} else {
				goto deliver_sig;
			}

		case (long)SIG_IGN:
			/*
			 * Masking above should prevent us ever trying
			 * to take action on an ignored signal other
			 * than SIGCONT, unless process is traced.
			 */
			if ((prop & SA_CONT) == 0 &&
			    (p->p_lflag & P_LTRACED) == 0) {
				printf("issignal\n");
			}
			break; /* ignore signal */

		default:
			/* This signal has an action - deliver it. */
			goto deliver_sig;
		}

		/* If we dropped through, the signal was ignored - remove it from pending list. */
		ut->uu_siglist &= ~mask;
	} /* for(;;) */

	/* NOTREACHED */

deliver_sig:
	ut->uu_siglist &= ~mask;
	retval = signum;

out:
	proc_signalend(p, 1);
	return retval;
}

/* called from _sleep */
int
CURSIG(proc_t p)
{
	int signum, mask, prop, sigbits;
	thread_t cur_act;
	struct uthread * ut;
	int retnum = 0;


	cur_act = current_thread();

	ut = get_bsdthread_info(cur_act);

	if (ut->uu_siglist == 0) {
		return 0;
	}

	if (((ut->uu_siglist & ~ut->uu_sigmask) == 0) && ((p->p_lflag & P_LTRACED) == 0)) {
		return 0;
	}

	sigbits = ut->uu_siglist & ~ut->uu_sigmask;

	for (;;) {
		if (p->p_lflag & P_LPPWAIT) {
			sigbits &= ~stopsigmask;
		}
		if (sigbits == 0) {             /* no signal to send */
			return retnum;
		}

		signum = ffs((unsigned int)sigbits);
		mask = sigmask(signum);
		prop = sigprop[signum];
		sigbits &= ~mask;               /* take the signal out */

		/*
		 * We should see pending but ignored signals
		 * only if P_LTRACED was on when they were posted.
		 */
		if (mask & p->p_sigignore && (p->p_lflag & P_LTRACED) == 0) {
			continue;
		}

		if (p->p_lflag & P_LTRACED && (p->p_lflag & P_LPPWAIT) == 0) {
			return signum;
		}

		/*
		 * Decide whether the signal should be returned.
		 * Return the signal's number, or fall through
		 * to clear it from the pending mask.
		 */

		switch ((long)SIGACTION(p, signum)) {
		case (long)SIG_DFL:
			/*
			 * If there is a pending stop signal to process
			 * with default action, stop here,
			 * then clear the signal.  However,
			 * if process is member of an orphaned
			 * process group, ignore tty stop signals.
			 */
			if (prop & SA_STOP) {
				struct pgrp *pg;

				pg = proc_pgrp(p, NULL);

				if (p->p_lflag & P_LTRACED ||
				    (pg->pg_jobc == 0 &&
				    prop & SA_TTYSTOP)) {
					pgrp_rele(pg);
					break;  /* == ignore */
				}
				pgrp_rele(pg);
				retnum = signum;
				break;
			} else if (prop & SA_IGNORE) {
				/*
				 * Except for SIGCONT, shouldn't get here.
				 * Default action is to ignore; drop it.
				 */
				break;          /* == ignore */
			} else {
				return signum;
			}
		/*NOTREACHED*/

		case (long)SIG_IGN:
			/*
			 * Masking above should prevent us ever trying
			 * to take action on an ignored signal other
			 * than SIGCONT, unless process is traced.
			 */
			if ((prop & SA_CONT) == 0 &&
			    (p->p_lflag & P_LTRACED) == 0) {
				printf("issignal\n");
			}
			break;          /* == ignore */

		default:
			/*
			 * This signal has an action, let
			 * postsig() process it.
			 */
			return signum;
		}
	}
	/* NOTREACHED */
}

/*
 * Put the argument process into the stopped state and notify the parent
 * via wakeup.  Signals are handled elsewhere.  The process must not be
 * on the run queue.
 */
static void
stop(proc_t p, proc_t parent)
{
	OSBitAndAtomic(~((uint32_t)P_CONTINUED), &p->p_flag);
	if ((parent != PROC_NULL) && (parent->p_stat != SSTOP)) {
		proc_list_lock();
		wakeup((caddr_t)parent);
		proc_list_unlock();
	}
	(void) task_suspend_internal(proc_task(p));
}

/*
 * Take the action for the specified signal
 * from the current set of pending signals.
 */
void
postsig_locked(int signum)
{
	proc_t p = current_proc();
	struct sigacts *ps = &p->p_sigacts;
	user_addr_t catcher;
	uint32_t code;
	int mask, returnmask;
	struct uthread * ut;
	os_reason_t ut_exit_reason = OS_REASON_NULL;
	int coredump_flags = 0;

#if DIAGNOSTIC
	if (signum == 0) {
		panic("postsig");
	}
	/*
	 *	This must be called on master cpu
	 */
	if (cpu_number() != master_cpu) {
		panic("psig not on master");
	}
#endif

	/*
	 * Try to grab the signal lock.
	 */
	if (sig_try_locked(p) <= 0) {
		return;
	}

	proc_signalstart(p, 1);

	ut = current_uthread();
	mask = sigmask(signum);
	ut->uu_siglist &= ~mask;
	catcher = SIGACTION(p, signum);
	if (catcher == SIG_DFL) {
		/*
		 * Default catcher, where the default is to kill
		 * the process.  (Other cases were ignored above.)
		 */

		/*
		 * exit_with_reason() below will consume a reference to the thread's exit reason, so we take another
		 * reference so the thread still has one even after we call exit_with_reason(). The thread's reference will
		 * ultimately be destroyed in uthread_cleanup().
		 */
		ut_exit_reason = ut->uu_exit_reason;
		os_reason_ref(ut_exit_reason);

		p->p_acflag |= AXSIG;
		if (sigprop[signum] & SA_CORE) {
			p->p_sigacts.ps_sig = signum;
			proc_signalend(p, 1);
			proc_unlock(p);
			if (task_is_driver(proc_task(p))) {
				coredump_flags |= COREDUMP_FULLFSYNC;
			}
#if CONFIG_COREDUMP
			if (coredump(p, 0, coredump_flags) == 0) {
				signum |= WCOREFLAG;
			}
#endif
		} else {
			proc_signalend(p, 1);
			proc_unlock(p);
		}

#if CONFIG_DTRACE
		bzero((caddr_t)&(ut->t_dtrace_siginfo), sizeof(ut->t_dtrace_siginfo));

		ut->t_dtrace_siginfo.si_signo = signum;
		ut->t_dtrace_siginfo.si_pid = p->si_pid;
		ut->t_dtrace_siginfo.si_uid = p->si_uid;
		ut->t_dtrace_siginfo.si_status = WEXITSTATUS(p->si_status);

		/* Fire DTrace proc:::fault probe when signal is generated by hardware. */
		switch (signum) {
		case SIGILL: case SIGBUS: case SIGSEGV: case SIGFPE: case SIGTRAP:
			DTRACE_PROC2(fault, int, (int)(ut->uu_code), siginfo_t *, &(ut->t_dtrace_siginfo));
			break;
		default:
			break;
		}


		DTRACE_PROC3(signal__handle, int, signum, siginfo_t *, &(ut->t_dtrace_siginfo),
		    void (*)(void), SIG_DFL);
#endif

		KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_FRCEXIT) | DBG_FUNC_NONE,
		    proc_getpid(p), W_EXITCODE(0, signum), 3, 0, 0);

		exit_with_reason(p, W_EXITCODE(0, signum), (int *)NULL, TRUE, TRUE, 0, ut_exit_reason);

		proc_lock(p);
		return;
	} else {
		/*
		 * If we get here, the signal must be caught.
		 */
#if DIAGNOSTIC
		if (catcher == SIG_IGN || (ut->uu_sigmask & mask)) {
			log(LOG_WARNING,
			    "postsig: processing masked or ignored signal\n");
		}
#endif

		/*
		 * Set the new mask value and also defer further
		 * occurences of this signal.
		 *
		 * Special case: user has done a sigpause.  Here the
		 * current mask is not of interest, but rather the
		 * mask from before the sigpause is what we want
		 * restored after the signal processing is completed.
		 */
		if (ut->uu_flag & UT_SAS_OLDMASK) {
			returnmask = ut->uu_oldmask;
			ut->uu_flag &= ~UT_SAS_OLDMASK;
			ut->uu_oldmask = 0;
		} else {
			returnmask = ut->uu_sigmask;
		}
		ut->uu_sigmask |= ps->ps_catchmask[signum];
		if ((ps->ps_signodefer & mask) == 0) {
			ut->uu_sigmask |= mask;
		}
		sigset_t siginfo = ps->ps_siginfo;
		if ((signum != SIGILL) && (signum != SIGTRAP) && (ps->ps_sigreset & mask)) {
			if ((signum != SIGCONT) && (sigprop[signum] & SA_IGNORE)) {
				p->p_sigignore |= mask;
			}
			if (SIGACTION(p, signum) != SIG_DFL) {
				proc_set_sigact(p, signum, SIG_DFL);
			}
			ps->ps_siginfo &= ~mask;
			ps->ps_signodefer &= ~mask;
		}

		if (ps->ps_sig != signum) {
			code = 0;
		} else {
			code = ps->ps_code;
			ps->ps_code = 0;
		}
		OSIncrementAtomicLong(&p->p_stats->p_ru.ru_nsignals);
		sendsig(p, catcher, signum, returnmask, code, siginfo);
	}
	proc_signalend(p, 1);
}

/*
 * Attach a signal knote to the list of knotes for this process.
 *
 * Signal knotes share the knote list with proc knotes.  This
 * could be avoided by using a signal-specific knote list, but
 * probably isn't worth the trouble.
 */

static int
filt_sigattach(struct knote *kn, __unused struct kevent_qos_s *kev)
{
	proc_t p = current_proc();  /* can attach only to oneself */

	proc_klist_lock();

	kn->kn_proc = p;
	kn->kn_flags |= EV_CLEAR; /* automatically set */
	kn->kn_sdata = 0;         /* incoming data is ignored */

	KNOTE_ATTACH(&p->p_klist, kn);

	proc_klist_unlock();

	/* edge-triggered events can't have fired before we attached */
	return 0;
}

/*
 * remove the knote from the process list, if it hasn't already
 * been removed by exit processing.
 */

static void
filt_sigdetach(struct knote *kn)
{
	proc_t p;

	proc_klist_lock();
	p = kn->kn_proc;
	if (p != NULL) {
		kn->kn_proc = NULL;
		KNOTE_DETACH(&p->p_klist, kn);
	}
	proc_klist_unlock();
}

/*
 * Post an event to the signal filter.  Because we share the same list
 * as process knotes, we have to filter out and handle only signal events.
 *
 * We assume that we process fdt_invalidate() before we post the NOTE_EXIT for
 * a process during exit.  Therefore, since signal filters can only be
 * set up "in-process", we should have already torn down the kqueue
 * hosting the EVFILT_SIGNAL knote and should never see NOTE_EXIT.
 */
static int
filt_signal(struct knote *kn, long hint)
{
	if (hint & NOTE_SIGNAL) {
		hint &= ~NOTE_SIGNAL;

		if (kn->kn_id == (unsigned int)hint) {
			kn->kn_hook32++;
		}
	} else if (hint & NOTE_EXIT) {
		panic("filt_signal: detected NOTE_EXIT event");
	}

	return kn->kn_hook32 != 0;
}

static int
filt_signaltouch(struct knote *kn, struct kevent_qos_s *kev)
{
#pragma unused(kev)

	int res;

	proc_klist_lock();

	/*
	 * No data to save - just capture if it is already fired
	 */
	res = (kn->kn_hook32 > 0);

	proc_klist_unlock();

	return res;
}

static int
filt_signalprocess(struct knote *kn, struct kevent_qos_s *kev)
{
	int res = 0;

	/*
	 * Snapshot the event data.
	 */

	proc_klist_lock();
	if (kn->kn_hook32) {
		knote_fill_kevent(kn, kev, kn->kn_hook32);
		kn->kn_hook32 = 0;
		res = 1;
	}
	proc_klist_unlock();
	return res;
}

void
bsd_ast(thread_t thread)
{
	proc_t p = current_proc();
	struct uthread *ut = get_bsdthread_info(thread);
	int     signum;
	static int bsd_init_done = 0;

	if (p == NULL) {
		return;
	}

	if (timerisset(&p->p_vtimer_user.it_value)) {
		uint32_t        microsecs;

		task_vtimer_update(proc_task(p), TASK_VTIMER_USER, &microsecs);

		if (!itimerdecr(p, &p->p_vtimer_user, microsecs)) {
			if (timerisset(&p->p_vtimer_user.it_value)) {
				task_vtimer_set(proc_task(p), TASK_VTIMER_USER);
			} else {
				task_vtimer_clear(proc_task(p), TASK_VTIMER_USER);
			}

			psignal_try_thread(p, thread, SIGVTALRM);
		}
	}

	if (timerisset(&p->p_vtimer_prof.it_value)) {
		uint32_t        microsecs;

		task_vtimer_update(proc_task(p), TASK_VTIMER_PROF, &microsecs);

		if (!itimerdecr(p, &p->p_vtimer_prof, microsecs)) {
			if (timerisset(&p->p_vtimer_prof.it_value)) {
				task_vtimer_set(proc_task(p), TASK_VTIMER_PROF);
			} else {
				task_vtimer_clear(proc_task(p), TASK_VTIMER_PROF);
			}

			psignal_try_thread(p, thread, SIGPROF);
		}
	}

	if (timerisset(&p->p_rlim_cpu)) {
		struct timeval          tv;

		task_vtimer_update(proc_task(p), TASK_VTIMER_RLIM, (uint32_t *) &tv.tv_usec);

		proc_spinlock(p);
		if (p->p_rlim_cpu.tv_sec > 0 || p->p_rlim_cpu.tv_usec > tv.tv_usec) {
			tv.tv_sec = 0;
			timersub(&p->p_rlim_cpu, &tv, &p->p_rlim_cpu);
			proc_spinunlock(p);
		} else {
			timerclear(&p->p_rlim_cpu);
			proc_spinunlock(p);

			task_vtimer_clear(proc_task(p), TASK_VTIMER_RLIM);

			psignal_try_thread(p, thread, SIGXCPU);
		}
	}

#if CONFIG_DTRACE
	if (ut->t_dtrace_sig) {
		uint8_t dt_action_sig = ut->t_dtrace_sig;
		ut->t_dtrace_sig = 0;
		psignal(p, dt_action_sig);
	}

	if (ut->t_dtrace_stop) {
		ut->t_dtrace_stop = 0;
		proc_lock(p);
		p->p_dtrace_stop = 1;
		proc_unlock(p);
		(void)task_suspend_internal(proc_task(p));
	}

	if (ut->t_dtrace_resumepid) {
		proc_t resumeproc = proc_find((int)ut->t_dtrace_resumepid);
		ut->t_dtrace_resumepid = 0;
		if (resumeproc != PROC_NULL) {
			proc_lock(resumeproc);
			/* We only act on processes stopped by dtrace */
			if (resumeproc->p_dtrace_stop) {
				resumeproc->p_dtrace_stop = 0;
				proc_unlock(resumeproc);
				task_resume_internal(proc_task(resumeproc));
			} else {
				proc_unlock(resumeproc);
			}
			proc_rele(resumeproc);
		}
	}

#endif /* CONFIG_DTRACE */

	proc_lock(p);
	if (CHECK_SIGNALS(p, current_thread(), ut)) {
		while ((signum = issignal_locked(p))) {
			postsig_locked(signum);
		}
	}
	proc_unlock(p);

	if (!bsd_init_done) {
		bsd_init_done = 1;
		bsdinit_task();
	}
}

/* ptrace set runnable */
void
pt_setrunnable(proc_t p)
{
	task_t task;

	task = proc_task(p);

	if (p->p_lflag & P_LTRACED) {
		proc_lock(p);
		p->p_stat = SRUN;
		proc_unlock(p);
		if (p->sigwait) {
			wakeup((caddr_t)&(p->sigwait));
			if ((p->p_lflag & P_LSIGEXC) == 0) {    // 5878479
				task_release(task);
			}
		}
	}
}

kern_return_t
do_bsdexception(
	int exc,
	int code,
	int sub)
{
	mach_exception_data_type_t   codes[EXCEPTION_CODE_MAX];

	codes[0] = code;
	codes[1] = sub;
	return bsd_exception(exc, codes, 2);
}

int
proc_pendingsignals(proc_t p, sigset_t mask)
{
	struct uthread * uth;
	sigset_t bits = 0;

	proc_lock(p);
	/* If the process is in proc exit return no signal info */
	if (p->p_lflag & P_LPEXIT) {
		goto out;
	}


	bits = 0;
	TAILQ_FOREACH(uth, &p->p_uthlist, uu_list) {
		bits |= (((uth->uu_siglist & ~uth->uu_sigmask) & ~p->p_sigignore) & mask);
	}
out:
	proc_unlock(p);
	return bits;
}

int
thread_issignal(proc_t p, thread_t th, sigset_t mask)
{
	struct uthread * uth;
	sigset_t  bits = 0;

	proc_lock(p);
	uth = (struct uthread *)get_bsdthread_info(th);
	if (uth) {
		bits = (((uth->uu_siglist & ~uth->uu_sigmask) & ~p->p_sigignore) & mask);
	}
	proc_unlock(p);
	return bits;
}

/*
 * Allow external reads of the sigprop array.
 */
int
hassigprop(int sig, int prop)
{
	return sigprop[sig] & prop;
}

void
pgsigio(pid_t pgid, int sig)
{
	proc_t p = PROC_NULL;

	if (pgid < 0) {
		gsignal(-(pgid), sig);
	} else if (pgid > 0 && (p = proc_find(pgid)) != 0) {
		psignal(p, sig);
	}
	if (p != PROC_NULL) {
		proc_rele(p);
	}
}

void
proc_signalstart(proc_t p, int locked)
{
	if (!locked) {
		proc_lock(p);
	}

	if (p->p_signalholder == current_thread()) {
		panic("proc_signalstart: thread attempting to signal a process for which it holds the signal lock");
	}

	p->p_sigwaitcnt++;
	while ((p->p_lflag & P_LINSIGNAL) == P_LINSIGNAL) {
		msleep(&p->p_sigmask, &p->p_mlock, 0, "proc_signstart", NULL);
	}
	p->p_sigwaitcnt--;

	p->p_lflag |= P_LINSIGNAL;
	p->p_signalholder = current_thread();
	if (!locked) {
		proc_unlock(p);
	}
}

void
proc_signalend(proc_t p, int locked)
{
	if (!locked) {
		proc_lock(p);
	}
	p->p_lflag &= ~P_LINSIGNAL;

	if (p->p_sigwaitcnt > 0) {
		wakeup(&p->p_sigmask);
	}

	p->p_signalholder = NULL;
	if (!locked) {
		proc_unlock(p);
	}
}

void
sig_lock_to_exit(proc_t p)
{
	thread_t        self = current_thread();

	p->exit_thread = self;
	proc_unlock(p);

	task_hold(proc_task(p));
	task_wait(proc_task(p), FALSE);

	proc_lock(p);
}

int
sig_try_locked(proc_t p)
{
	thread_t        self = current_thread();

	while (p->sigwait || p->exit_thread) {
		if (p->exit_thread) {
			return 0;
		}
		msleep((caddr_t)&p->sigwait_thread, &p->p_mlock, PCATCH | PDROP, 0, 0);
		if (thread_should_abort(self)) {
			/*
			 * Terminate request - clean up.
			 */
			proc_lock(p);
			return -1;
		}
		proc_lock(p);
	}
	return 1;
}