OS-4406 native signalfd support

23 files changed, 1320 insertions, 1 deletions

diff --git a/manifest b/manifest
index fd04ed0ebf..1c6e3a09c8 100644
--- a/manifest
+++ b/manifest
@@ -4196,6 +4196,7 @@ f usr/include/sys/shm_impl.h 0644 root bin
 f usr/include/sys/sid.h 0644 root bin
 f usr/include/sys/siginfo.h 0644 root bin
 f usr/include/sys/signal.h 0644 root bin
+f usr/include/sys/signalfd.h 0644 root bin
 f usr/include/sys/sleepq.h 0644 root bin
 f usr/include/sys/smbios.h 0644 root bin
 f usr/include/sys/smbios_impl.h 0644 root bin
@@ -4529,6 +4530,7 @@ f usr/kernel/drv/amd64/pm 0755 root sys
 f usr/kernel/drv/amd64/pool 0755 root sys
 f usr/kernel/drv/amd64/ptm 0755 root sys
 f usr/kernel/drv/amd64/pts 0755 root sys
+f usr/kernel/drv/amd64/signalfd 0755 root sys
 f usr/kernel/drv/amd64/smbsrv 0755 root sys
 f usr/kernel/drv/amd64/sppp 0755 root sys
 f usr/kernel/drv/amd64/sppptun 0755 root sys
@@ -4553,6 +4555,7 @@ f usr/kernel/drv/pm.conf 0644 root sys
 f usr/kernel/drv/pool.conf 0644 root sys
 f usr/kernel/drv/ptm.conf 0644 root sys
 f usr/kernel/drv/pts.conf 0644 root sys
+f usr/kernel/drv/signalfd.conf 0644 root sys
 f usr/kernel/drv/smbsrv.conf 0644 root sys
 f usr/kernel/drv/sppp.conf 0644 root sys
 f usr/kernel/drv/sppptun.conf 0644 root sys
@@ -13513,6 +13516,7 @@ f usr/share/man/man3c/siginterrupt.3c 0444 root bin
 s usr/share/man/man3c/sigismember.3c=sigsetops.3c
 s usr/share/man/man3c/siglongjmp.3c=setjmp.3c
 f usr/share/man/man3c/signal.3c 0444 root bin
+f usr/share/man/man3c/signalfd.3c 0444 root bin
 s usr/share/man/man3c/sigpause.3c=signal.3c
 f usr/share/man/man3c/sigqueue.3c 0444 root bin
 s usr/share/man/man3c/sigrelse.3c=signal.3c
diff --git a/usr/src/cmd/devfsadm/misc_link.c b/usr/src/cmd/devfsadm/misc_link.c
index fa55eb401f..55aff1e4f7 100644
--- a/usr/src/cmd/devfsadm/misc_link.c
+++ b/usr/src/cmd/devfsadm/misc_link.c
@@ -94,6 +94,9 @@ static devfsadm_create_t misc_cbt[] = {
 	{ "pseudo", "ddi_pseudo", "eventfd",
 	    TYPE_EXACT | DRV_EXACT, ILEVEL_0, minor_name
 	},
+	{ "pseudo", "ddi_pseudo", "signalfd",
+	    TYPE_EXACT | DRV_EXACT, ILEVEL_0, minor_name
+	},
 	{ "pseudo", "ddi_pseudo", "rsm",
 	    TYPE_EXACT | DRV_EXACT, ILEVEL_0, minor_name
 	},
diff --git a/usr/src/lib/libc/amd64/Makefile b/usr/src/lib/libc/amd64/Makefile
index dc86e1a197..af70e66123 100644
--- a/usr/src/lib/libc/amd64/Makefile
+++ b/usr/src/lib/libc/amd64/Makefile
@@ -904,6 +904,7 @@ PORTSYS=			\
 	sidsys.o		\
 	siginterrupt.o		\
 	signal.o		\
+	signalfd.o		\
 	sigpending.o		\
 	sigstack.o		\
 	stat.o			\
diff --git a/usr/src/lib/libc/i386/Makefile.com b/usr/src/lib/libc/i386/Makefile.com
index 9896614023..241afc45cb 100644
--- a/usr/src/lib/libc/i386/Makefile.com
+++ b/usr/src/lib/libc/i386/Makefile.com
@@ -944,6 +944,7 @@ PORTSYS=			\
 	sidsys.o		\
 	siginterrupt.o		\
 	signal.o		\
+	signalfd.o		\
 	sigpending.o		\
 	sigstack.o		\
 	stat.o			\
diff --git a/usr/src/lib/libc/port/mapfile-vers b/usr/src/lib/libc/port/mapfile-vers
index 56f372fe80..296e49fe3b 100644
--- a/usr/src/lib/libc/port/mapfile-vers
+++ b/usr/src/lib/libc/port/mapfile-vers
@@ -3003,6 +3003,7 @@ $endif
 	_so_shutdown;
 	_so_socket;
 	_so_socketpair;
+	signalfd;
 	str2group;
 	str2passwd;
 	str2spwd;
diff --git a/usr/src/lib/libc/port/sys/signalfd.c b/usr/src/lib/libc/port/sys/signalfd.c
new file mode 100644
index 0000000000..0080c52bdf
--- /dev/null
+++ b/usr/src/lib/libc/port/sys/signalfd.c
@@ -0,0 +1,60 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2015, Joyent, Inc.
+ */
+
+#include <sys/signalfd.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+int
+signalfd(int fd, const sigset_t *mask, int flags)
+{
+	int origfd = fd;
+
+	if (fd == -1) {
+		int oflags = O_RDONLY;
+
+		if (flags & ~(SFD_NONBLOCK | SFD_CLOEXEC)) {
+			errno = EINVAL;
+			return (-1);
+		}
+
+		if (flags & SFD_NONBLOCK)
+			oflags |= O_NONBLOCK;
+
+		if (flags & SFD_CLOEXEC)
+			oflags |= O_CLOEXEC;
+
+		if ((fd = open("/dev/signalfd", oflags)) < 0)
+			return (-1);
+	}
+
+	if (ioctl(fd, SIGNALFDIOC_MASK, mask) != 0) {
+		if (origfd == -1) {
+			int old = errno;
+			(void) close(fd);
+			errno = old;
+		}
+		/*
+		 * Trying to modify an existing sigfd so if this failed
+		 * it's because it's not a valid fd or not a sigfd. ioctl
+		 * returns the correct errno for these cases.
+		 */
+		return (-1);
+	}
+
+	return (fd);
+}
diff --git a/usr/src/lib/libc/sparc/Makefile.com b/usr/src/lib/libc/sparc/Makefile.com
index 1e54306c85..2091b1bd3c 100644
--- a/usr/src/lib/libc/sparc/Makefile.com
+++ b/usr/src/lib/libc/sparc/Makefile.com
@@ -978,6 +978,7 @@ PORTSYS=			\
 	sidsys.o		\
 	siginterrupt.o		\
 	signal.o		\
+	signalfd.o		\
 	sigpending.o		\
 	sigstack.o		\
 	stat.o			\
diff --git a/usr/src/man/man3c/Makefile b/usr/src/man/man3c/Makefile
index 47b3014510..975c56e921 100644
--- a/usr/src/man/man3c/Makefile
+++ b/usr/src/man/man3c/Makefile
@@ -415,6 +415,7 @@ MANFILES= 	__fbufsize.3c					\
 	 	sigfpe.3c					\
 	 	siginterrupt.3c					\
 	 	signal.3c					\
+		signalfd.3c					\
 	 	sigqueue.3c					\
 	 	sigsetops.3c					\
 	 	sigstack.3c					\
diff --git a/usr/src/man/man3c/signalfd.3c b/usr/src/man/man3c/signalfd.3c
new file mode 100644
index 0000000000..43699a50a5
--- /dev/null
+++ b/usr/src/man/man3c/signalfd.3c
@@ -0,0 +1,192 @@
+.\"
+.\"  This file and its contents are supplied under the terms of the
+.\"  Common Development and Distribution License ("CDDL"), version 1.0.
+.\"  You may only use this file in accordance with the terms of version
+.\"  1.0 of the CDDL.
+.\" 
+.\"  A full copy of the text of the CDDL should have accompanied this
+.\"  source.  A copy of the CDDL is also available via the Internet at
+.\"  http://www.illumos.org/license/CDDL.
+.\"
+.\"  Copyright 2015, Joyent, Inc.
+.\"
+.Dd "Jun 15, 2015"
+.Dt SIGNALFD 3C
+.Os
+.Sh NAME
+.Nm signalfd
+.Nd create or modify a file descriptor for signal handling
+.Sh SYNOPSIS
+.In sys/signalfd.h
+.
+.Ft int
+.Fo signalfd
+.Fa "int fd"
+.Fa "const sigset_t *mask"
+.Fa "int flags"
+.Fc
+.
+.Sh DESCRIPTION
+The
+.Fn signalfd
+function returns a file descriptor that can be used
+for synchronous consumption of signals. The file descriptor can be operated
+upon via
+.Xr read 2
+and the facilities that notify of file descriptor activity (e.g.
+.Xr poll 2 ,
+.Xr port_get 3C ,
+.Xr epoll_wait 3C
+). To dispose of the instance
+.Xr close 2
+should be called on the file descriptor.
+.Pp
+If the
+.Va fd
+argument is -1, a new signalfd file descriptor will be
+returned, otherwise the
+.Va fd
+argument should be an existing signalfd file descriptor whose signal mask will
+be updated.
+.Pp
+The
+.Va mask
+argument specifies the set of signals that are relevant to the file descriptor.
+It may be manipulated with the standard signal set manipulation functions
+documented in
+.Xr sigsetops 3C .
+Signals in the mask which cannot be caught (e.g.
+.Fa SIGKILL )
+are ignored.
+.Pp
+The
+.Va flags
+argument specifies additional parameters for the instance, and can have any of
+the following values:
+.Bl -tag -width Dv
+.It Sy SFD_CLOEXEC
+Instance will be closed upon an
+.Xr exec 2 ;
+see description for
+.Fa O_CLOEXEC
+in
+.Xr open 2 .
+.It Sy SFD_NONBLOCK
+Instance will be set to be non-blocking. A
+.Xr read 2
+on a signalfd instance that has been initialized with
+.Fa SFD_NONBLOCK ,
+or made non-blocking in other ways, will return
+.Er EAGAIN
+in lieu of blocking if there are no signals from the
+.Va mask
+that are pending.
+.El
+.Pp
+As with
+.Xr sigwait 2 ,
+reading a signal from the file descriptor will consume the signal. The signals
+used with signalfd file descriptors are normally first blocked so that their
+handler does not run when a signal arrives. If the signal is not blocked the
+behavior matches that of
+.Xr sigwait 2 ;
+if a
+.Xr read 2
+is pending then the signal is consumed by the read, otherwise the signal is
+consumed by the handler.
+.Pp
+The following operations can be performed upon a signalfd file descriptor:
+.Bl -tag -width Dv
+.It Sy read(2)
+Reads and consumes one or more of the pending signals that match the file
+descriptor's
+.Va mask .
+The read buffer must be large enough to hold one or more
+.Vt signalfd_siginfo
+structures, which is described below.
+.Xr read 2
+will block if there are no matching signals pending, or return
+.Er EAGAIN
+if the instance was created with
+.Fa SFD_NONBLOCK .
+After a
+.Xr fork 2 ,
+if the child reads from the descriptor it will only consume signals from itself.
+.It Sy poll(2)
+Provide notification when one of the signals from the
+.Va mask
+arrives.
+.Fa POLLIN
+and
+.Fa POLLRDNORM
+will be set.
+.It Sy close(2)
+Closes the desriptor.
+.El
+.Pp
+The
+.Vt signalfd_siginfo
+structure returned from
+.Xr read 2
+is a fixed size 128 byte structure defined as follows:
+.Bd -literal
+typedef struct signalfd_siginfo {
+        uint32_t ssi_signo;     /* signal from signal.h */
+        int32_t  ssi_errno;     /* error from errno.h */
+        int32_t  ssi_code;      /* signal code */
+        uint32_t ssi_pid;       /* PID of sender */
+        uint32_t ssi_uid;       /* real UID of sender */
+        int32_t  ssi_fd;        /* file descriptor (SIGIO) */
+        uint32_t ssi_tid;       /* unused */
+        uint32_t ssi_band;      /* band event (SIGIO) */
+        uint32_t ssi_overrun;   /* unused */
+        uint32_t ssi_trapno;    /* trap number that caused signal */
+        int32_t  ssi_status;    /* exit status or signal (SIGCHLD) */
+        int32_t  ssi_int;       /* unused */
+        uint64_t ssi_ptr;       /* unused */
+        uint64_t ssi_utime;     /* user CPU time consumed (SIGCHLD) */
+        uint64_t ssi_stime;     /* system CPU time consumed (SIGCHLD) */
+        uint64_t ssi_addr;      /* address that generated signal */
+        uint8_t  ssi_pad[48];   /* pad size to 128 bytes */
+} signalfd_siginfo_t;
+.Ed
+.Sh RETURN VALUES
+Upon succesful completion, a file descriptor associated with the instance
+is returned. Otherwise, -1 is returned and errno is set to indicate the error.
+When
+.Va fd
+is not -1 and there is no error, the value of
+.Va fd
+is returned.
+.Sh ERRORS
+The
+.Fn signalfd function
+will fail if:
+.Bl -tag -width Er
+.It Er EBADF
+The
+.Va fd
+descriptor is invalid.
+.It Er EFAULT
+The
+.Va mask
+address is invalid.
+.It Er EINVAL
+The
+.Va fd
+descriptor is not a signalfd descriptor or the
+.Va flags
+are invalid.
+.It Er EMFILE
+There are currently
+.Va  OPEN_MAX
+file descriptors open in the calling process.
+.It Er ENODEV
+Unable to allocate state for the file descriptor.
+.El
+.Sh SEE ALSO
+.Xr poll 2 ,
+.Xr sigwait 2 ,
+.Xr sigsetops 3C ,
+.Xr sigwaitinfo 3C ,
+.Xr signal.h 3HEAD
diff --git a/usr/src/uts/common/Makefile.files b/usr/src/uts/common/Makefile.files
index d7a58d0529..50ab92b081 100644
--- a/usr/src/uts/common/Makefile.files
+++ b/usr/src/uts/common/Makefile.files
@@ -1011,6 +1011,8 @@ DEVPOOL_OBJS += devpool.o
 
 EVENTFD_OBJS +=	eventfd.o
 
+SIGNALFD_OBJS += signalfd.o
+
 I8042_OBJS +=	i8042.o
 
 INOTIFY_OBJS +=	inotify.o
diff --git a/usr/src/uts/common/io/signalfd.c b/usr/src/uts/common/io/signalfd.c
new file mode 100644
index 0000000000..3b9b76e7f4
--- /dev/null
+++ b/usr/src/uts/common/io/signalfd.c
@@ -0,0 +1,762 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2015 Joyent, Inc.
+ */
+
+/*
+ * Support for the signalfd facility, a Linux-borne facility for
+ * file descriptor-based synchronous signal consumption.
+ *
+ * As described on the signalfd(3C) man page, the general idea behind these
+ * file descriptors is that they can be used to synchronously consume signals
+ * via the read(2) syscall. That capability already exists with the
+ * sigwaitinfo(3C) function but the key advantage of signalfd is that, because
+ * it is file descriptor based, poll(2) can be used to determine when signals
+ * are available to be consumed.
+ *
+ * The general implementation uses signalfd_state to hold both the signal set
+ * and poll head for an open file descriptor. Because a process can be using
+ * different sigfds with different signal sets, each signalfd_state poll head
+ * can be thought of as an independent signal stream and the thread(s) waiting
+ * on that stream will get poll notification when any signal in the
+ * corresponding set is received.
+ *
+ * The sigfd_proc_state_t struct lives on the proc_t and maintains per-proc
+ * state for function callbacks and data when the proc needs to do work during
+ * signal delivery for pollwakeup.
+ *
+ * The read side of the implementation is straightforward and mimics the
+ * kernel behavior for sigtimedwait(). Signals continue to live on either
+ * the proc's p_sig, or thread's t_sig, member. Read consumes the signal so
+ * that it is no longer pending.
+ *
+ * The poll side is more complex since all of the sigfds on the process need
+ * to be examined every time a signal is delivered to the process in order to
+ * determine if any thread is waiting in poll for that signal.
+ *
+ * Because it is likely that a process will only be using a few sigfds, but
+ * perhaps many total file descriptors, we maintain a list of sigfds (which
+ * may need pollwakeup) that lives on the proc's p_sigfd struct. In this way
+ * only a few of the state structs will need to be examined every time a signal
+ * is delivered to the process, instead of having to examine all of the file
+ * descriptors to find the state structs.
+ *
+ * When a state struct with a matching signal set is found, if there are any
+ * threads waiting in poll for that signal, then pollwakeup is called.
+ *
+ * Forking causes some complications with sigfd polling because now two
+ * processes have a fd that references the same signalfd_state, but signals go
+ * to only one of those processes. Because the state struct is referenced by
+ * both file descriptors, and the state struct represents a signal stream to be
+ * polled, it can be confusing as to which processes should get a pollwakeup.
+ * Fortunately this is not a common problem in practice, but the implementation
+ * goes to some length to mitigate unexpected behavior.
+ *
+ * When the parent process forks (or forkall), if any thread is in poll then
+ * both the parent and child will return from poll with EINTR. This means
+ * that if either process wants to re-poll on a sigfd then it needs to re-run
+ * poll. Our fork helper function will cleanup all of the poll state on the
+ * parent process and null-out the state pointers on the child process. In this
+ * way the state will only get reestablished on either process when one of them
+ * does another poll on the sigfd. Under normal circumstances the child will
+ * close the sigfd, so it never does a re-poll, and signal delivery for the
+ * child will never come into our code path.
+ *
+ * This leaves only one odd corner case. If the parent and child both use
+ * the dup-ed sigfd to poll then when a signal is delivered to either process
+ * there is no way to determine which one should get the pollwakeup (since
+ * both processes will be queued on the same signal stream poll head). What
+ * happens in this case is that both processes will return from poll, but only
+ * one of them will actually have a signal to read. The other will return
+ * from read with EAGAIN, or block. This case is actually similar to the
+ * situation within a single process which got two different sigfd's with the
+ * same mask (or poll on two fd's that are dup-ed). Both would return from poll
+ * when a signal arrives but only one read would consume the signal and the
+ * other read would fail or block. Applications which poll on shared fd's
+ * cannot assume that a subsequent read will actually obtain data.
+ */
+
+#include <sys/ddi.h>
+#include <sys/sunddi.h>
+#include <sys/signalfd.h>
+#include <sys/conf.h>
+#include <sys/sysmacros.h>
+#include <sys/filio.h>
+#include <sys/stat.h>
+#include <sys/file.h>
+#include <sys/schedctl.h>
+#include <sys/id_space.h>
+#include <sys/sdt.h>
+
+typedef struct signalfd_state signalfd_state_t;
+
+struct signalfd_state {
+	kmutex_t sfd_lock;			/* lock protecting state */
+	pollhead_t sfd_pollhd;			/* poll head */
+	k_sigset_t sfd_set;			/* signals for this fd */
+	signalfd_state_t *sfd_next;		/* next state on global list */
+};
+
+/*
+ * Internal global variables.
+ */
+static kmutex_t		signalfd_lock;		/* lock protecting state */
+static dev_info_t	*signalfd_devi;		/* device info */
+static major_t		signalfd_major;
+static id_space_t	*signalfd_minor;	/* minor number arena */
+static void		*signalfd_softstate;	/* softstate pointer */
+static signalfd_state_t	*signalfd_state;	/* global list of state */
+
+/*
+ * If we don't already have an entry in the proc's list for this state, add one.
+ */
+static void
+signalfd_wake_list_add(signalfd_state_t *state)
+{
+	proc_t *p = curproc;
+	list_t *lst;
+	sigfd_wake_list_t *wlp;
+
+	ASSERT(MUTEX_HELD(&p->p_lock));
+	ASSERT(p->p_sigfd != NULL);
+
+	lst = &((sigfd_proc_state_t *)p->p_sigfd)->sigfd_list;
+	for (wlp = list_head(lst); wlp != NULL; wlp = list_next(lst, wlp)) {
+		if (wlp->sigfd_wl_state == state)
+			break;
+	}
+
+	if (wlp == NULL) {
+		wlp = kmem_zalloc(sizeof (sigfd_wake_list_t), KM_SLEEP);
+		wlp->sigfd_wl_state = state;
+		list_insert_head(lst, wlp);
+	}
+}
+
+static void
+signalfd_wake_rm(list_t *lst, sigfd_wake_list_t *wlp)
+{
+	list_remove(lst, wlp);
+	kmem_free(wlp, sizeof (sigfd_wake_list_t));
+}
+
+static void
+signalfd_wake_list_rm(proc_t *p, signalfd_state_t *state)
+{
+	sigfd_wake_list_t *wlp;
+	list_t *lst;
+
+	ASSERT(MUTEX_HELD(&p->p_lock));
+
+	if (p->p_sigfd == NULL)
+		return;
+
+	lst = &((sigfd_proc_state_t *)p->p_sigfd)->sigfd_list;
+	for (wlp = list_head(lst); wlp != NULL; wlp = list_next(lst, wlp)) {
+		if (wlp->sigfd_wl_state == state) {
+			signalfd_wake_rm(lst, wlp);
+			break;
+		}
+	}
+}
+
+static void
+signalfd_wake_list_cleanup(proc_t *p)
+{
+	sigfd_wake_list_t *wlp;
+	list_t *lst;
+
+	ASSERT(MUTEX_HELD(&p->p_lock));
+
+	((sigfd_proc_state_t *)p->p_sigfd)->sigfd_pollwake_cb = NULL;
+
+	lst = &((sigfd_proc_state_t *)p->p_sigfd)->sigfd_list;
+	while (!list_is_empty(lst)) {
+		wlp = (sigfd_wake_list_t *)list_remove_head(lst);
+		kmem_free(wlp, sizeof (sigfd_wake_list_t));
+	}
+}
+
+static void
+signalfd_exit_helper()
+{
+	proc_t *p = curproc;
+	list_t *lst;
+
+	/* This being non-null is the only way we can get here */
+	ASSERT(p->p_sigfd != NULL);
+
+	mutex_enter(&p->p_lock);
+	lst = &((sigfd_proc_state_t *)p->p_sigfd)->sigfd_list;
+
+	signalfd_wake_list_cleanup(p);
+	list_destroy(lst);
+	kmem_free(p->p_sigfd, sizeof (sigfd_proc_state_t));
+	p->p_sigfd = NULL;
+	mutex_exit(&p->p_lock);
+}
+
+/*
+ * Clear the parent's signal state list and pollwakeup callback. The child
+ * starts with no signal pollwakeup state. That will be added when needed if
+ * the child needs pollwakeup later.
+ */
+static void
+signalfd_fork_helper(struct proc *p, struct proc *cp)
+{
+	/* This being non-null is the only way we can get here */
+	ASSERT(p->p_sigfd != NULL);
+
+	mutex_enter(&p->p_lock);
+	signalfd_wake_list_cleanup(p);
+	mutex_exit(&p->p_lock);
+	cp->p_sigfd = NULL;
+}
+
+/*
+ * Called every time a signal is delivered to the process so that we can
+ * see if any signal stream needs a pollwakeup. We maintain a list of
+ * signal state elements so that we don't have to look at every file descriptor
+ * on the process. If necessary, a further optimization would be to maintain a
+ * signal set mask that is a union of all of the sets in the list so that
+ * we don't even traverse the list if the signal is not in one of the elements.
+ * However, since the list is likely to be very short, this is not currently
+ * being done. A more complex data structure might also be used, but it is
+ * unclear what that would be since each signal set needs to be checked for a
+ * match.
+ */
+static void
+signalfd_pollwake_cb(void *arg0, int sig)
+{
+	proc_t *p = (proc_t *)arg0;
+	list_t *lst;
+	sigfd_wake_list_t *wlp;
+
+	ASSERT(MUTEX_HELD(&p->p_lock));
+
+	if (p->p_sigfd == NULL)
+		return;
+
+	lst = &((sigfd_proc_state_t *)p->p_sigfd)->sigfd_list;
+	wlp = list_head(lst);
+	while (wlp != NULL) {
+		signalfd_state_t *state = wlp->sigfd_wl_state;
+
+		mutex_enter(&state->sfd_lock);
+
+		if (sigismember(&state->sfd_set, sig) &&
+		    state->sfd_pollhd.ph_list != NULL) {
+			sigfd_wake_list_t *tmp = wlp;
+
+			/* remove it from the list */
+			wlp = list_next(lst, wlp);
+			signalfd_wake_rm(lst, tmp);
+
+			mutex_exit(&state->sfd_lock);
+			pollwakeup(&state->sfd_pollhd, POLLRDNORM | POLLIN);
+		} else {
+			mutex_exit(&state->sfd_lock);
+			wlp = list_next(lst, wlp);
+		}
+	}
+}
+
+/*ARGSUSED*/
+static int
+signalfd_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
+{
+	signalfd_state_t *state;
+	major_t major = getemajor(*devp);
+	minor_t minor = getminor(*devp);
+
+	if (minor != SIGNALFDMNRN_SIGNALFD)
+		return (ENXIO);
+
+	mutex_enter(&signalfd_lock);
+
+	minor = (minor_t)id_allocff(signalfd_minor);
+
+	if (ddi_soft_state_zalloc(signalfd_softstate, minor) != DDI_SUCCESS) {
+		id_free(signalfd_minor, minor);
+		mutex_exit(&signalfd_lock);
+		return (ENODEV);
+	}
+
+	state = ddi_get_soft_state(signalfd_softstate, minor);
+	*devp = makedevice(major, minor);
+
+	state->sfd_next = signalfd_state;
+	signalfd_state = state;
+
+	mutex_exit(&signalfd_lock);
+
+	return (0);
+}
+
+/*
+ * Consume one signal from our set in a manner similar to sigtimedwait().
+ * The block parameter is used to control whether we wait for a signal or
+ * return immediately if no signal is pending. We use the thread's t_sigwait
+ * member in the same way that it is used by sigtimedwait.
+ *
+ * Return 0 if we successfully consumed a signal or an errno if not.
+ */
+static int
+consume_signal(k_sigset_t set, uio_t *uio, boolean_t block)
+{
+	k_sigset_t oldmask;
+	kthread_t *t = curthread;
+	klwp_t *lwp = ttolwp(t);
+	proc_t *p = ttoproc(t);
+	timespec_t now;
+	timespec_t *rqtp = NULL;	/* null means blocking */
+	int timecheck = 0;
+	int ret = 0;
+	k_siginfo_t info, *infop;
+	signalfd_siginfo_t ssi, *ssp = &ssi;
+
+	if (block == B_FALSE) {
+		timecheck = timechanged;
+		gethrestime(&now);
+		rqtp = &now;	/* non-blocking check for pending signals */
+	}
+
+	t->t_sigwait = set;
+
+	mutex_enter(&p->p_lock);
+	/*
+	 * set the thread's signal mask to unmask those signals in the
+	 * specified set.
+	 */
+	schedctl_finish_sigblock(t);
+	oldmask = t->t_hold;
+	sigdiffset(&t->t_hold, &t->t_sigwait);
+
+	/*
+	 * Based on rqtp, wait indefinitely until we take a signal in our set
+	 * or return immediately if there are no signals pending from our set.
+	 */
+	while ((ret = cv_waituntil_sig(&t->t_delay_cv, &p->p_lock, rqtp,
+	    timecheck)) > 0)
+		continue;
+
+	/* Restore thread's signal mask to its previous value. */
+	t->t_hold = oldmask;
+	t->t_sig_check = 1;	/* so post_syscall sees new t_hold mask */
+
+	if (ret == -1) {
+		/* no signals pending */
+		mutex_exit(&p->p_lock);
+		sigemptyset(&t->t_sigwait);
+		return (EAGAIN);	/* no signals pending */
+	}
+
+	/* Don't bother with signal if it is not in request set. */
+	if (lwp->lwp_cursig == 0 ||
+	    !sigismember(&t->t_sigwait, lwp->lwp_cursig)) {
+		mutex_exit(&p->p_lock);
+		/*
+		 * lwp_cursig is zero if pokelwps() awakened cv_wait_sig().
+		 * This happens if some other thread in this process called
+		 * forkall() or exit().
+		 */
+		sigemptyset(&t->t_sigwait);
+		return (EINTR);
+	}
+
+	if (lwp->lwp_curinfo) {
+		infop = &lwp->lwp_curinfo->sq_info;
+	} else {
+		infop = &info;
+		bzero(infop, sizeof (info));
+		infop->si_signo = lwp->lwp_cursig;
+		infop->si_code = SI_NOINFO;
+	}
+
+	lwp->lwp_ru.nsignals++;
+
+	DTRACE_PROC2(signal__clear, int, ret, ksiginfo_t *, infop);
+	lwp->lwp_cursig = 0;
+	lwp->lwp_extsig = 0;
+	mutex_exit(&p->p_lock);
+
+	/* Convert k_siginfo into external, datamodel independent, struct. */
+	bzero(ssp, sizeof (*ssp));
+	ssp->ssi_signo = infop->si_signo;
+	ssp->ssi_errno = infop->si_errno;
+	ssp->ssi_code = infop->si_code;
+	ssp->ssi_pid = infop->si_pid;
+	ssp->ssi_uid = infop->si_uid;
+	ssp->ssi_fd = infop->si_fd;
+	ssp->ssi_band = infop->si_band;
+	ssp->ssi_trapno = infop->si_trapno;
+	ssp->ssi_status = infop->si_status;
+	ssp->ssi_utime = infop->si_utime;
+	ssp->ssi_stime = infop->si_stime;
+	ssp->ssi_addr = (uint64_t)(intptr_t)infop->si_addr;
+
+	ret = uiomove(ssp, sizeof (*ssp), UIO_READ, uio);
+
+	if (lwp->lwp_curinfo) {
+		siginfofree(lwp->lwp_curinfo);
+		lwp->lwp_curinfo = NULL;
+	}
+	sigemptyset(&t->t_sigwait);
+	return (ret);
+}
+
+/*
+ * This is similar to sigtimedwait. Based on the fd mode we may wait until a
+ * signal within our specified set is posted. We consume as many available
+ * signals within our set as we can.
+ */
+/*ARGSUSED*/
+static int
+signalfd_read(dev_t dev, uio_t *uio, cred_t *cr)
+{
+	signalfd_state_t *state;
+	minor_t minor = getminor(dev);
+	boolean_t block = B_TRUE;
+	k_sigset_t set;
+	boolean_t got_one = B_FALSE;
+	int res;
+
+	if (uio->uio_resid < sizeof (signalfd_siginfo_t))
+		return (EINVAL);
+
+	state = ddi_get_soft_state(signalfd_softstate, minor);
+
+	if (uio->uio_fmode & (FNDELAY|FNONBLOCK))
+		block = B_FALSE;
+
+	mutex_enter(&state->sfd_lock);
+	set = state->sfd_set;
+	mutex_exit(&state->sfd_lock);
+
+	if (sigisempty(&set))
+		return (set_errno(EINVAL));
+
+	do  {
+		res = consume_signal(state->sfd_set, uio, block);
+		if (res == 0)
+			got_one = B_TRUE;
+
+		/*
+		 * After consuming one signal we won't block trying to consume
+		 * further signals.
+		 */
+		block = B_FALSE;
+	} while (res == 0 && uio->uio_resid >= sizeof (signalfd_siginfo_t));
+
+	if (got_one)
+		res = 0;
+
+	return (res);
+}
+
+/*
+ * If ksigset_t's were a single word, we would do:
+ *      return (((p->p_sig | t->t_sig) & set) & fillset);
+ */
+static int
+signalfd_sig_pending(proc_t *p, kthread_t *t, k_sigset_t set)
+{
+	return (((p->p_sig.__sigbits[0] | t->t_sig.__sigbits[0]) &
+	    set.__sigbits[0]) |
+	    ((p->p_sig.__sigbits[1] | t->t_sig.__sigbits[1]) &
+	    set.__sigbits[1]) |
+	    (((p->p_sig.__sigbits[2] | t->t_sig.__sigbits[2]) &
+	    set.__sigbits[2]) & FILLSET2));
+}
+
+/*ARGSUSED*/
+static int
+signalfd_poll(dev_t dev, short events, int anyyet, short *reventsp,
+    struct pollhead **phpp)
+{
+	signalfd_state_t *state;
+	minor_t minor = getminor(dev);
+	kthread_t *t = curthread;
+	proc_t *p = ttoproc(t);
+	short revents = 0;
+
+	state = ddi_get_soft_state(signalfd_softstate, minor);
+
+	mutex_enter(&state->sfd_lock);
+
+	if (signalfd_sig_pending(p, t, state->sfd_set) != 0)
+		revents |= POLLRDNORM | POLLIN;
+
+	mutex_exit(&state->sfd_lock);
+
+	if (!(*reventsp = revents & events) && !anyyet) {
+		*phpp = &state->sfd_pollhd;
+
+		/*
+		 * Enable pollwakeup handling.
+		 */
+		if (p->p_sigfd == NULL) {
+			sigfd_proc_state_t *pstate;
+
+			pstate = kmem_zalloc(sizeof (sigfd_proc_state_t),
+			    KM_SLEEP);
+			list_create(&pstate->sigfd_list,
+			    sizeof (sigfd_wake_list_t),
+			    offsetof(sigfd_wake_list_t, sigfd_wl_lst));
+
+			mutex_enter(&p->p_lock);
+			/* check again now that we're locked */
+			if (p->p_sigfd == NULL) {
+				p->p_sigfd = pstate;
+			} else {
+				/* someone beat us to it */
+				list_destroy(&pstate->sigfd_list);
+				kmem_free(pstate, sizeof (sigfd_proc_state_t));
+			}
+			mutex_exit(&p->p_lock);
+		}
+
+		mutex_enter(&p->p_lock);
+		if (((sigfd_proc_state_t *)p->p_sigfd)->sigfd_pollwake_cb ==
+		    NULL) {
+			((sigfd_proc_state_t *)p->p_sigfd)->sigfd_pollwake_cb =
+			    signalfd_pollwake_cb;
+		}
+		signalfd_wake_list_add(state);
+		mutex_exit(&p->p_lock);
+	}
+
+	return (0);
+}
+
+/*ARGSUSED*/
+static int
+signalfd_ioctl(dev_t dev, int cmd, intptr_t arg, int md, cred_t *cr, int *rv)
+{
+	signalfd_state_t *state;
+	minor_t minor = getminor(dev);
+	sigset_t mask;
+
+	state = ddi_get_soft_state(signalfd_softstate, minor);
+
+	switch (cmd) {
+	case SIGNALFDIOC_MASK:
+		if (copyin((caddr_t)arg, (caddr_t)&mask, sizeof (sigset_t)))
+			return (set_errno(EFAULT));
+
+		mutex_enter(&state->sfd_lock);
+		sigutok(&mask, &state->sfd_set);
+		mutex_exit(&state->sfd_lock);
+
+		return (0);
+
+	default:
+		break;
+	}
+
+	return (ENOTTY);
+}
+
+/*ARGSUSED*/
+static int
+signalfd_close(dev_t dev, int flag, int otyp, cred_t *cred_p)
+{
+	signalfd_state_t *state, **sp;
+	minor_t minor = getminor(dev);
+	proc_t *p = curproc;
+
+	state = ddi_get_soft_state(signalfd_softstate, minor);
+
+	if (state->sfd_pollhd.ph_list != NULL) {
+		pollwakeup(&state->sfd_pollhd, POLLERR);
+		pollhead_clean(&state->sfd_pollhd);
+	}
+
+	/* Make sure our state is removed from our proc's pollwake list. */
+	mutex_enter(&p->p_lock);
+	signalfd_wake_list_rm(p, state);
+	mutex_exit(&p->p_lock);
+
+	mutex_enter(&signalfd_lock);
+
+	/* Remove our state from our global list. */
+	for (sp = &signalfd_state; *sp != state; sp = &((*sp)->sfd_next))
+		VERIFY(*sp != NULL);
+
+	*sp = (*sp)->sfd_next;
+
+	ddi_soft_state_free(signalfd_softstate, minor);
+	id_free(signalfd_minor, minor);
+
+	mutex_exit(&signalfd_lock);
+
+	return (0);
+}
+
+/*ARGSUSED*/
+static int
+signalfd_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
+{
+	if (cmd != DDI_ATTACH || signalfd_devi != NULL)
+		return (DDI_FAILURE);
+
+	mutex_enter(&signalfd_lock);
+
+	signalfd_minor = id_space_create("signalfd_minor", 1, L_MAXMIN32 + 1);
+	if (!signalfd_minor)
+		return (DDI_FAILURE);
+
+	if (ddi_soft_state_init(&signalfd_softstate,
+	    sizeof (signalfd_state_t), 0) != 0) {
+		cmn_err(CE_NOTE, "/dev/signalfd failed to create soft state");
+		id_space_destroy(signalfd_minor);
+		mutex_exit(&signalfd_lock);
+		return (DDI_FAILURE);
+	}
+
+	if (ddi_create_minor_node(devi, "signalfd", S_IFCHR,
+	    SIGNALFDMNRN_SIGNALFD, DDI_PSEUDO, NULL) == DDI_FAILURE) {
+		cmn_err(CE_NOTE, "/dev/signalfd couldn't create minor node");
+		ddi_soft_state_fini(&signalfd_softstate);
+		id_space_destroy(signalfd_minor);
+		mutex_exit(&signalfd_lock);
+		return (DDI_FAILURE);
+	}
+
+	ddi_report_dev(devi);
+	signalfd_devi = devi;
+	signalfd_major = ddi_driver_major(signalfd_devi);
+
+	sigfd_fork_helper = signalfd_fork_helper;
+	sigfd_exit_helper = signalfd_exit_helper;
+
+	mutex_exit(&signalfd_lock);
+
+	return (DDI_SUCCESS);
+}
+
+/*ARGSUSED*/
+static int
+signalfd_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
+{
+	switch (cmd) {
+	case DDI_DETACH:
+		break;
+
+	case DDI_SUSPEND:
+		return (DDI_SUCCESS);
+
+	default:
+		return (DDI_FAILURE);
+	}
+
+	/* list should be empty */
+	VERIFY(signalfd_state == NULL);
+
+	mutex_enter(&signalfd_lock);
+	id_space_destroy(signalfd_minor);
+
+	ddi_remove_minor_node(signalfd_devi, NULL);
+	signalfd_devi = NULL;
+	sigfd_fork_helper = NULL;
+	sigfd_exit_helper = NULL;
+
+	ddi_soft_state_fini(&signalfd_softstate);
+	mutex_exit(&signalfd_lock);
+
+	return (DDI_SUCCESS);
+}
+
+/*ARGSUSED*/
+static int
+signalfd_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
+{
+	int error;
+
+	switch (infocmd) {
+	case DDI_INFO_DEVT2DEVINFO:
+		*result = (void *)signalfd_devi;
+		error = DDI_SUCCESS;
+		break;
+	case DDI_INFO_DEVT2INSTANCE:
+		*result = (void *)0;
+		error = DDI_SUCCESS;
+		break;
+	default:
+		error = DDI_FAILURE;
+	}
+	return (error);
+}
+
+static struct cb_ops signalfd_cb_ops = {
+	signalfd_open,		/* open */
+	signalfd_close,		/* close */
+	nulldev,		/* strategy */
+	nulldev,		/* print */
+	nodev,			/* dump */
+	signalfd_read,		/* read */
+	nodev,			/* write */
+	signalfd_ioctl,		/* ioctl */
+	nodev,			/* devmap */
+	nodev,			/* mmap */
+	nodev,			/* segmap */
+	signalfd_poll,		/* poll */
+	ddi_prop_op,		/* cb_prop_op */
+	0,			/* streamtab  */
+	D_NEW | D_MP		/* Driver compatibility flag */
+};
+
+static struct dev_ops signalfd_ops = {
+	DEVO_REV,		/* devo_rev */
+	0,			/* refcnt */
+	signalfd_info,		/* get_dev_info */
+	nulldev,		/* identify */
+	nulldev,		/* probe */
+	signalfd_attach,	/* attach */
+	signalfd_detach,	/* detach */
+	nodev,			/* reset */
+	&signalfd_cb_ops,	/* driver operations */
+	NULL,			/* bus operations */
+	nodev,			/* dev power */
+	ddi_quiesce_not_needed,	/* quiesce */
+};
+
+static struct modldrv modldrv = {
+	&mod_driverops,		/* module type (this is a pseudo driver) */
+	"signalfd support",	/* name of module */
+	&signalfd_ops,		/* driver ops */
+};
+
+static struct modlinkage modlinkage = {
+	MODREV_1,
+	(void *)&modldrv,
+	NULL
+};
+
+int
+_init(void)
+{
+	return (mod_install(&modlinkage));
+}
+
+int
+_info(struct modinfo *modinfop)
+{
+	return (mod_info(&modlinkage, modinfop));
+}
+
+int
+_fini(void)
+{
+	return (mod_remove(&modlinkage));
+}
diff --git a/usr/src/uts/common/io/signalfd.conf b/usr/src/uts/common/io/signalfd.conf
new file mode 100644
index 0000000000..de44738a14
--- /dev/null
+++ b/usr/src/uts/common/io/signalfd.conf
@@ -0,0 +1,16 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2015 Joyent, Inc.
+#
+
+name="signalfd" parent="pseudo" instance=0;
diff --git a/usr/src/uts/common/os/exit.c b/usr/src/uts/common/os/exit.c
index 06a3856332..6e3884946c 100644
--- a/usr/src/uts/common/os/exit.c
+++ b/usr/src/uts/common/os/exit.c
@@ -491,6 +491,14 @@ proc_exit(int why, int what)
 		(*dtrace_helpers_cleanup)();
 	}
 
+	/*
+	 * Clean up any signalfd state for the process.
+	 */
+	if (p->p_sigfd != NULL) {
+		VERIFY(sigfd_exit_helper != NULL);
+		(*sigfd_exit_helper)();
+	}
+
 	/* untimeout the realtime timers */
 	if (p->p_itimer != NULL)
 		timer_exit();
diff --git a/usr/src/uts/common/os/fork.c b/usr/src/uts/common/os/fork.c
index fcd33a7788..522731f5e2 100644
--- a/usr/src/uts/common/os/fork.c
+++ b/usr/src/uts/common/os/fork.c
@@ -331,6 +331,14 @@ cfork(int isvfork, int isfork1, int flags)
 	}
 
 	/*
+	 * Setup signalfd state.
+	 */
+	if (p->p_sigfd != NULL) {
+		VERIFY(sigfd_fork_helper != NULL);
+		(*sigfd_fork_helper)(p, cp);
+	}
+
+	/*
 	 * Duplicate parent's resource controls.
 	 */
 	dup_set = rctl_set_create();
diff --git a/usr/src/uts/common/os/sig.c b/usr/src/uts/common/os/sig.c
index bc48c6e6e8..cc2e753526 100644
--- a/usr/src/uts/common/os/sig.c
+++ b/usr/src/uts/common/os/sig.c
@@ -61,6 +61,7 @@
 #include <sys/dtrace.h>
 #include <sys/sdt.h>
 #include <sys/brand.h>
+#include <sys/signalfd.h>
 
 const k_sigset_t nullsmask = {0, 0, 0};
 
@@ -95,6 +96,13 @@ const k_sigset_t holdvfork =
 static	int	isjobstop(int);
 static	void	post_sigcld(proc_t *, sigqueue_t *);
 
+
+/*
+ * signalfd helper functions which are set when the signalfd driver loads.
+ */
+void (*sigfd_fork_helper)(struct proc *, struct proc *);
+void (*sigfd_exit_helper)();
+
 /*
  * Internal variables for counting number of user thread stop requests posted.
  * They may not be accurate at some special situation such as that a virtually
@@ -323,6 +331,11 @@ sigtoproc(proc_t *p, kthread_t *t, int sig)
 		(void) eat_signal(t, sig);
 		thread_unlock(t);
 		DTRACE_PROC2(signal__send, kthread_t *, t, int, sig);
+		if (p->p_sigfd != NULL && ((sigfd_proc_state_t *)
+		    (p->p_sigfd))->sigfd_pollwake_cb != NULL)
+			(*((sigfd_proc_state_t *)(p->p_sigfd))->
+			    sigfd_pollwake_cb)(p, sig);
+
 	} else if ((tt = p->p_tlist) != NULL) {
 		/*
 		 * Make sure that some lwp that already exists
@@ -361,6 +374,10 @@ sigtoproc(proc_t *p, kthread_t *t, int sig)
 		}
 
 		DTRACE_PROC2(signal__send, kthread_t *, tt, int, sig);
+		if (p->p_sigfd != NULL && ((sigfd_proc_state_t *)
+		    (p->p_sigfd))->sigfd_pollwake_cb != NULL)
+			(*((sigfd_proc_state_t *)(p->p_sigfd))->
+			    sigfd_pollwake_cb)(p, sig);
 	}
 }
 
diff --git a/usr/src/uts/common/sys/Makefile b/usr/src/uts/common/sys/Makefile
index a6537c9db3..b646989821 100644
--- a/usr/src/uts/common/sys/Makefile
+++ b/usr/src/uts/common/sys/Makefile
@@ -512,6 +512,7 @@ CHKHDRS=			\
 	sid.h			\
 	siginfo.h		\
 	signal.h		\
+	signalfd.h		\
 	sleepq.h		\
 	smbios.h		\
 	smbios_impl.h		\
diff --git a/usr/src/uts/common/sys/proc.h b/usr/src/uts/common/sys/proc.h
index e811bebf25..9704748b71 100644
--- a/usr/src/uts/common/sys/proc.h
+++ b/usr/src/uts/common/sys/proc.h
@@ -48,6 +48,7 @@
 #include <sys/list.h>
 #include <sys/avl.h>
 #include <sys/door_impl.h>
+#include <sys/signalfd.h>
 
 #ifdef	__cplusplus
 extern "C" {
@@ -198,6 +199,7 @@ typedef struct	proc {
 	k_sigset_t p_extsig;		/* signals sent from another contract */
 	k_sigset_t p_ignore;		/* ignore when generated */
 	k_sigset_t p_siginfo;		/* gets signal info with signal */
+	void *p_sigfd;			/* signalfd support state */
 	struct sigqueue *p_sigqueue;	/* queued siginfo structures */
 	struct sigqhdr *p_sigqhdr;	/* hdr to sigqueue structure pool */
 	struct sigqhdr *p_signhdr;	/* hdr to signotify structure pool */
diff --git a/usr/src/uts/common/sys/signalfd.h b/usr/src/uts/common/sys/signalfd.h
new file mode 100644
index 0000000000..11a0483652
--- /dev/null
+++ b/usr/src/uts/common/sys/signalfd.h
@@ -0,0 +1,101 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2015 Joyent, Inc.
+ */
+
+/*
+ * Header file to support the signalfd facility. Note that this facility
+ * is designed to be binary compatible with the Linux signalfd facility, modulo
+ * the signals themselves; values for constants here should therefore exactly
+ * match those found in Linux, and this facility shouldn't be extended
+ * independently of Linux.
+ */
+
+#ifndef _SYS_SIGNALFD_H
+#define	_SYS_SIGNALFD_H
+
+#include <sys/types.h>
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+/*
+ * To assure binary compatibility with Linux, these values are fixed at their
+ * Linux equivalents, not their native ones.
+ */
+#define	SFD_CLOEXEC		02000000		/* LX_O_CLOEXEC */
+#define	SFD_NONBLOCK		04000			/* LX_O_NONBLOCK */
+
+/*
+ * These ioctl values are specific to the native implementation; applications
+ * shouldn't be using them directly, and they should therefore be safe to
+ * change without breaking apps.
+ */
+#define	SIGNALFDIOC		(('s' << 24) | ('f' << 16) | ('d' << 8))
+#define	SIGNALFDIOC_MASK	(SIGNALFDIOC | 1)	/* set mask */
+
+typedef struct signalfd_siginfo {
+	uint32_t ssi_signo;	/* signal from signal.h */
+	int32_t  ssi_errno;	/* error from errno.h */
+	int32_t  ssi_code;	/* signal code */
+	uint32_t ssi_pid;	/* PID of sender */
+	uint32_t ssi_uid;	/* real UID of sender */
+	int32_t  ssi_fd;	/* File descriptor (SIGIO) */
+	uint32_t ssi_tid;	/* unused */
+	uint32_t ssi_band;	/* band event (SIGIO) */
+	uint32_t ssi_overrun;	/* unused */
+	uint32_t ssi_trapno;	/* trap number that caused signal */
+	int32_t  ssi_status;	/* exit status or signal (SIGCHLD) */
+	int32_t  ssi_int;	/* unused */
+	uint64_t ssi_ptr;	/* unused */
+	uint64_t ssi_utime;	/* user CPU time consumed (SIGCHLD) */
+	uint64_t ssi_stime;	/* system CPU time consumed (SIGCHLD) */
+	uint64_t ssi_addr;	/* address that generated signal */
+	uint8_t  ssi_pad[48];	/* Pad size to 128 bytes to allow for */
+				/* additional fields in the future. */
+} signalfd_siginfo_t;
+
+#ifndef _KERNEL
+
+extern int signalfd(int, const sigset_t *, int);
+
+#else
+
+#define	SIGNALFDMNRN_SIGNALFD	0
+#define	SIGNALFDMNRN_CLONE	1
+
+typedef struct sigfd_wake_list {
+	list_node_t sigfd_wl_lst;
+	void *sigfd_wl_state;
+} sigfd_wake_list_t;
+
+/*
+ * This holds the proc_t state for a process which is using signalfd.
+ */
+typedef struct sigfd_proc_state {
+	void (*sigfd_pollwake_cb)(void *, int);
+	list_t sigfd_list;
+} sigfd_proc_state_t;
+
+
+extern void (*sigfd_fork_helper)(struct proc *, struct proc *);
+extern void (*sigfd_exit_helper)();
+
+#endif /* _KERNEL */
+
+#ifdef	__cplusplus
+}
+#endif
+
+#endif	/* _SYS_SIGNALFD_H */
diff --git a/usr/src/uts/common/sys/thread.h b/usr/src/uts/common/sys/thread.h
index 41ea2331df..53deb90e23 100644
--- a/usr/src/uts/common/sys/thread.h
+++ b/usr/src/uts/common/sys/thread.h
@@ -170,7 +170,7 @@ typedef struct _kthread {
 	k_sigset_t	t_sig;		/* signals pending to this process */
 	k_sigset_t	t_extsig;	/* signals sent from another contract */
 	k_sigset_t	t_hold;		/* hold signal bit mask */
-	k_sigset_t	t_sigwait;	/* sigtimedwait() is accepting these */
+	k_sigset_t	t_sigwait;	/* sigtimedwait/sigfd accepting these */
 	struct	_kthread *t_forw;	/* process's forward thread link */
 	struct	_kthread *t_back;	/* process's backward thread link */
 	struct	_kthread *t_thlink;	/* tid (lwpid) lookup hash link */
diff --git a/usr/src/uts/intel/Makefile.intel b/usr/src/uts/intel/Makefile.intel
index cdc0da3940..7f0e97a5b3 100644
--- a/usr/src/uts/intel/Makefile.intel
+++ b/usr/src/uts/intel/Makefile.intel
@@ -327,6 +327,7 @@ DRV_KMODS	+= sd
 DRV_KMODS	+= sdhost
 DRV_KMODS	+= sgen
 DRV_KMODS	+= si3124
+DRV_KMODS	+= signalfd
 DRV_KMODS	+= smbios
 DRV_KMODS	+= skd
 DRV_KMODS	+= softmac
diff --git a/usr/src/uts/intel/signalfd/Makefile b/usr/src/uts/intel/signalfd/Makefile
new file mode 100644
index 0000000000..d1a461c2f1
--- /dev/null
+++ b/usr/src/uts/intel/signalfd/Makefile
@@ -0,0 +1,68 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2015 Joyent, Inc.
+#
+
+#
+#	Path to the base of the uts directory tree (usually /usr/src/uts).
+#
+UTSBASE	= ../..
+
+#
+#	Define the module and object file sets.
+#
+MODULE		= signalfd
+OBJECTS		= $(SIGNALFD_OBJS:%=$(OBJS_DIR)/%)
+LINTS		= $(SIGNALFD_OBJS:%.o=$(LINTS_DIR)/%.ln)
+ROOTMODULE	= $(USR_DRV_DIR)/$(MODULE)
+CONF_SRCDIR	= $(UTSBASE)/common/io
+
+#
+#	Include common rules.
+#
+include $(UTSBASE)/intel/Makefile.intel
+
+CERRWARN	+= -_gcc=-Wno-parentheses
+
+#
+#	Define targets
+#
+ALL_TARGET	= $(BINARY) $(SRC_CONFILE)
+LINT_TARGET	= $(MODULE).lint
+INSTALL_TARGET	= $(BINARY) $(ROOTMODULE) $(ROOT_CONFFILE)
+
+#
+#	Default build targets.
+#
+.KEEP_STATE:
+
+def:		$(DEF_DEPS)
+
+all:		$(ALL_DEPS)
+
+clean:		$(CLEAN_DEPS)
+
+clobber:	$(CLOBBER_DEPS)
+
+lint:		$(LINT_DEPS)
+
+modlintlib:	$(MODLINTLIB_DEPS)
+
+clean.lint:	$(CLEAN_LINT_DEPS)
+
+install:	$(INSTALL_DEPS)
+
+#
+#	Include common targets.
+#
+include $(UTSBASE)/intel/Makefile.targ
diff --git a/usr/src/uts/sparc/Makefile.sparc b/usr/src/uts/sparc/Makefile.sparc
index 3e790ed1ed..e8458de8e3 100644
--- a/usr/src/uts/sparc/Makefile.sparc
+++ b/usr/src/uts/sparc/Makefile.sparc
@@ -240,6 +240,7 @@ DRV_KMODS	+= bpf
 DRV_KMODS	+= dca
 DRV_KMODS	+= inotify
 DRV_KMODS	+= eventfd
+DRV_KMODS	+= signalfd
 DRV_KMODS	+= timerfd
 
 #
diff --git a/usr/src/uts/sparc/signalfd/Makefile b/usr/src/uts/sparc/signalfd/Makefile
new file mode 100644
index 0000000000..a60bc617e1
--- /dev/null
+++ b/usr/src/uts/sparc/signalfd/Makefile
@@ -0,0 +1,68 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2015 Joyent, Inc.
+#
+
+#
+#	Path to the base of the uts directory tree (usually /usr/src/uts).
+#
+UTSBASE	= ../..
+
+#
+#	Define the module and object file sets.
+#
+MODULE		= signalfd
+OBJECTS		= $(SIGNALFD_OBJS:%=$(OBJS_DIR)/%)
+LINTS		= $(SIGNALFD_OBJS:%.o=$(LINTS_DIR)/%.ln)
+ROOTMODULE	= $(USR_DRV_DIR)/$(MODULE)
+CONF_SRCDIR	= $(UTSBASE)/common/io
+
+#
+#	Include common rules.
+#
+include $(UTSBASE)/sparc/Makefile.sparc
+
+CERRWARN	+= -_gcc=-Wno-parentheses
+
+#
+#	Define targets
+#
+ALL_TARGET	= $(BINARY) $(SRC_CONFILE)
+LINT_TARGET	= $(MODULE).lint
+INSTALL_TARGET	= $(BINARY) $(ROOTMODULE) $(ROOT_CONFFILE)
+
+#
+#	Default build targets.
+#
+.KEEP_STATE:
+
+def:		$(DEF_DEPS)
+
+all:		$(ALL_DEPS)
+
+clean:		$(CLEAN_DEPS)
+
+clobber:	$(CLOBBER_DEPS)
+
+lint:		$(LINT_DEPS)
+
+modlintlib:	$(MODLINTLIB_DEPS)
+
+clean.lint:	$(CLEAN_LINT_DEPS)
+
+install:	$(INSTALL_DEPS)
+
+#
+#	Include common targets.
+#
+include $(UTSBASE)/sparc/Makefile.targ