Index: amd64/amd64/machdep.c
===================================================================
--- amd64/amd64/machdep.c	(revision 274791)
+++ amd64/amd64/machdep.c	(working copy)
@@ -331,7 +331,7 @@
  * specified pc, psl.
  */
 void
-sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct sigframe sf, *sfp;
 	struct pcb *pcb;
@@ -406,7 +406,7 @@
 	regs->tf_rdi = sig;			/* arg 1 in %rdi */
 	regs->tf_rdx = (register_t)&sfp->sf_uc;	/* arg 3 in %rdx */
 	bzero(&sf.sf_si, sizeof(sf.sf_si));
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		regs->tf_rsi = (register_t)&sfp->sf_si;	/* arg 2 in %rsi */
 		sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;
Index: amd64/ia32/ia32_signal.c
===================================================================
--- amd64/ia32/ia32_signal.c	(revision 274791)
+++ amd64/ia32/ia32_signal.c	(working copy)
@@ -82,7 +82,7 @@
 #include <machine/cpufunc.h>
 
 #ifdef COMPAT_FREEBSD4
-static void freebsd4_ia32_sendsig(sig_t, ksiginfo_t *, sigset_t *);
+static void freebsd4_ia32_sendsig(sig_t, ksiginfo_t *, sigset_t *, u_int32_t);
 #endif
 
 #define	CS_SECURE(cs)		(ISPL(cs) == SEL_UPL)
@@ -332,7 +332,7 @@
 
 #ifdef COMPAT_43
 static void
-ia32_osendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+ia32_osendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct ia32_sigframe3 sf, *fp;
 	struct proc *p;
@@ -367,7 +367,7 @@
 	/* Build the argument list for the signal handler. */
 	sf.sf_signum = sig;
 	sf.sf_scp = (register_t)&fp->sf_siginfo.si_sc;
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_arg2 = (register_t)&fp->sf_siginfo;
 		sf.sf_siginfo.si_signo = sig;
@@ -434,7 +434,7 @@
 
 #ifdef COMPAT_FREEBSD4
 static void
-freebsd4_ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+freebsd4_ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct ia32_sigframe4 sf, *sfp;
 	struct siginfo32 siginfo;
@@ -506,7 +506,7 @@
 	sf.sf_signum = sig;
 	sf.sf_ucontext = (register_t)&sfp->sf_uc;
 	bzero(&sf.sf_si, sizeof(sf.sf_si));
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_siginfo = (u_int32_t)(uintptr_t)&sfp->sf_si;
 		sf.sf_ah = (u_int32_t)(uintptr_t)catcher;
@@ -549,7 +549,7 @@
 #endif	/* COMPAT_FREEBSD4 */
 
 void
-ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct ia32_sigframe sf, *sfp;
 	struct siginfo32 siginfo;
@@ -571,13 +571,13 @@
 	psp = p->p_sigacts;
 #ifdef COMPAT_FREEBSD4
 	if (SIGISMEMBER(psp->ps_freebsd4, sig)) {
-		freebsd4_ia32_sendsig(catcher, ksi, mask);
+		freebsd4_ia32_sendsig(catcher, ksi, mask, flags);
 		return;
 	}
 #endif
 #ifdef COMPAT_43
 	if (SIGISMEMBER(psp->ps_osigset, sig)) {
-		ia32_osendsig(catcher, ksi, mask);
+		ia32_osendsig(catcher, ksi, mask, flags);
 		return;
 	}
 #endif
@@ -651,7 +651,7 @@
 	sf.sf_signum = sig;
 	sf.sf_ucontext = (register_t)&sfp->sf_uc;
 	bzero(&sf.sf_si, sizeof(sf.sf_si));
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_siginfo = (u_int32_t)(uintptr_t)&sfp->sf_si;
 		sf.sf_ah = (u_int32_t)(uintptr_t)catcher;
Index: amd64/linux32/linux32_sysvec.c
===================================================================
--- amd64/linux32/linux32_sysvec.c	(revision 274791)
+++ amd64/linux32/linux32_sysvec.c	(working copy)
@@ -122,7 +122,8 @@
 static int	elf_linux_fixup(register_t **stack_base,
 		    struct image_params *iparams);
 static register_t *linux_copyout_strings(struct image_params *imgp);
-static void     linux_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask);
+static void     linux_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask,
+			      u_int32_t);
 static void	exec_linux_setregs(struct thread *td, 
 				   struct image_params *imgp, u_long stack);
 static void	linux32_fixlimit(struct rlimit *rl, int which);
@@ -299,7 +300,7 @@
 extern unsigned long linux_sznonrtsigcode;
 
 static void
-linux_rt_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+linux_rt_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct thread *td = curthread;
 	struct proc *p = td->td_proc;
@@ -327,7 +328,7 @@
 	 * Allocate space for the signal handler context.
 	 */
 	if ((td->td_pflags & TDP_ALTSTACK) && !oonstack &&
-	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
+	    (flags & SENDSIG_SIGINFO)) {
 		fp = (struct l_rt_sigframe *)(td->td_sigstk.ss_sp +
 		    td->td_sigstk.ss_size - sizeof(struct l_rt_sigframe));
 	} else
Index: compat/ia32/ia32_signal.h
===================================================================
--- compat/ia32/ia32_signal.h	(revision 274791)
+++ compat/ia32/ia32_signal.h	(working copy)
@@ -200,7 +200,7 @@
 extern int sz_freebsd4_ia32_sigcode;
 extern int sz_ia32_osigcode;
 extern int sz_lcall_tramp;
-void ia32_sendsig(sig_t, struct ksiginfo *, sigset_t *);
+void ia32_sendsig(sig_t, struct ksiginfo *, sigset_t *, u_int32_t);
 void ia32_setregs(struct thread *td, struct image_params *imgp,
     u_long stack);
 int setup_lcall_gate(void);
Index: compat/svr4/svr4_signal.h
===================================================================
--- compat/svr4/svr4_signal.h	(revision 274791)
+++ compat/svr4/svr4_signal.h	(working copy)
@@ -139,6 +139,6 @@
 void bsd_to_svr4_sigset(const sigset_t *, svr4_sigset_t *);
 void svr4_to_bsd_sigaltstack(const struct svr4_sigaltstack *, struct sigaltstack *);
 void svr4_to_bsd_sigset(const svr4_sigset_t *, sigset_t *);
-void svr4_sendsig(sig_t, struct ksiginfo *, sigset_t  *);
+void svr4_sendsig(sig_t, struct ksiginfo *, sigset_t  *, u_int32_t);
 
 #endif /* !_SVR4_SIGNAL_H_ */
Index: i386/i386/machdep.c
===================================================================
--- i386/i386/machdep.c	(revision 274791)
+++ i386/i386/machdep.c	(working copy)
@@ -221,10 +221,10 @@
 int cold = 1;
 
 #ifdef COMPAT_43
-static void osendsig(sig_t catcher, ksiginfo_t *, sigset_t *mask);
+static void osendsig(sig_t catcher, ksiginfo_t *, sigset_t *mask, u_int32_t);
 #endif
 #ifdef COMPAT_FREEBSD4
-static void freebsd4_sendsig(sig_t catcher, ksiginfo_t *, sigset_t *mask);
+static void freebsd4_sendsig(sig_t catcher, ksiginfo_t *, sigset_t *mask, u_int32_t);
 #endif
 
 long Maxmem = 0;
@@ -373,7 +373,7 @@
  */
 #ifdef COMPAT_43
 static void
-osendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+osendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct osigframe sf, *fp;
 	struct proc *p;
@@ -411,7 +411,7 @@
 	sf.sf_signum = sig;
 	sf.sf_scp = (register_t)&fp->sf_siginfo.si_sc;
 	bzero(&sf.sf_siginfo, sizeof(sf.sf_siginfo));
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_arg2 = (register_t)&fp->sf_siginfo;
 		sf.sf_siginfo.si_signo = sig;
@@ -509,7 +509,7 @@
 
 #ifdef COMPAT_FREEBSD4
 static void
-freebsd4_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+freebsd4_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct sigframe4 sf, *sfp;
 	struct proc *p;
@@ -562,7 +562,7 @@
 	sf.sf_signum = sig;
 	sf.sf_ucontext = (register_t)&sfp->sf_uc;
 	bzero(&sf.sf_si, sizeof(sf.sf_si));
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_siginfo = (register_t)&sfp->sf_si;
 		sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;
@@ -635,7 +635,7 @@
 #endif	/* COMPAT_FREEBSD4 */
 
 void
-sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct sigframe sf, *sfp;
 	struct proc *p;
@@ -734,7 +734,7 @@
 	sf.sf_signum = sig;
 	sf.sf_ucontext = (register_t)&sfp->sf_uc;
 	bzero(&sf.sf_si, sizeof(sf.sf_si));
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		sf.sf_siginfo = (register_t)&sfp->sf_si;
 		sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;
Index: i386/linux/linux_sysvec.c
===================================================================
--- i386/linux/linux_sysvec.c	(revision 274791)
+++ i386/linux/linux_sysvec.c	(working copy)
@@ -105,7 +105,8 @@
 		    struct image_params *iparams);
 static int	elf_linux_fixup(register_t **stack_base,
 		    struct image_params *iparams);
-static void     linux_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask);
+static void     linux_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask,
+			      u_int32_t);
 static void	exec_linux_setregs(struct thread *td,
 		    struct image_params *imgp, u_long stack);
 static register_t *linux_copyout_strings(struct image_params *imgp);
@@ -537,7 +538,7 @@
  * specified pc, psl.
  */
 static void
-linux_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+linux_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct thread *td = curthread;
 	struct proc *p = td->td_proc;
@@ -553,7 +554,7 @@
 	sig = ksi->ksi_signo;
 	code = ksi->ksi_code;
 	mtx_assert(&psp->ps_mtx, MA_OWNED);
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		linux_rt_sendsig(catcher, ksi, mask);
 		return;
Index: i386/svr4/svr4_machdep.c
===================================================================
--- i386/svr4/svr4_machdep.c	(revision 274791)
+++ i386/svr4/svr4_machdep.c	(working copy)
@@ -410,10 +410,11 @@
  * will return to the user pc, psl.
  */
 void
-svr4_sendsig(catcher, ksi, mask)
+svr4_sendsig(catcher, ksi, mask, flags)
 	sig_t catcher;
 	ksiginfo_t *ksi;
 	sigset_t *mask;
+	u_int32_t flags;
 {
 	register struct thread *td = curthread;
 	struct proc *p = td->td_proc;
Index: kern/kern_sig.c
===================================================================
--- kern/kern_sig.c	(revision 274791)
+++ kern/kern_sig.c	(working copy)
@@ -1895,6 +1895,7 @@
 	struct proc *p;
 	int sig;
 	int code;
+	u_int32_t ss_flags = 0;
 
 	p = td->td_proc;
 	sig = ksi->ksi_signo;
@@ -1907,6 +1908,8 @@
 	if ((p->p_flag & P_TRACED) == 0 && SIGISMEMBER(ps->ps_sigcatch, sig) &&
 	    !SIGISMEMBER(td->td_sigmask, sig)) {
 		td->td_ru.ru_nsignals++;
+		if (SIGISMEMBER(ps->ps_siginfo, sig))
+			ss_flags |= SENDSIG_SIGINFO;
 #ifdef KTRACE
 		if (KTRPOINT(curthread, KTR_PSIG))
 			ktrpsig(sig, ps->ps_sigact[_SIG_IDX(sig)],
@@ -1913,7 +1916,7 @@
 			    &td->td_sigmask, code);
 #endif
 		(*p->p_sysent->sv_sendsig)(ps->ps_sigact[_SIG_IDX(sig)],
-				ksi, &td->td_sigmask);
+				ksi, &td->td_sigmask, ss_flags);
 		mask = ps->ps_catchmask[_SIG_IDX(sig)];
 		if (!SIGISMEMBER(ps->ps_signodefer, sig))
 			SIGADDSET(mask, sig);
@@ -2803,6 +2806,7 @@
 	sig_t action;
 	ksiginfo_t ksi;
 	sigset_t returnmask, mask;
+	u_int32_t ss_flags = 0;
 
 	KASSERT(sig != 0, ("postsig"));
 
@@ -2843,6 +2847,11 @@
 		KASSERT(action != SIG_IGN && !SIGISMEMBER(td->td_sigmask, sig),
 		    ("postsig action"));
 		/*
+		 * Set SENDSIG_SIGINFO early: sigdflt() may remove it.
+		 */
+		if (SIGISMEMBER(ps->ps_siginfo, sig))
+			ss_flags |= SENDSIG_SIGINFO;
+		/*
 		 * Set the new mask value and also defer further
 		 * occurrences of this signal.
 		 *
@@ -2870,7 +2879,7 @@
 			p->p_code = 0;
 			p->p_sig = 0;
 		}
-		(*p->p_sysent->sv_sendsig)(action, &ksi, &returnmask);
+		(*p->p_sysent->sv_sendsig)(action, &ksi, &returnmask, ss_flags);
 	}
 	return (1);
 }
Index: mips/mips/freebsd32_machdep.c
===================================================================
--- mips/mips/freebsd32_machdep.c	(revision 274791)
+++ mips/mips/freebsd32_machdep.c	(working copy)
@@ -69,7 +69,7 @@
 static void freebsd32_exec_setregs(struct thread *, struct image_params *, u_long);
 static int get_mcontext32(struct thread *, mcontext32_t *, int);
 static int set_mcontext32(struct thread *, const mcontext32_t *);
-static void freebsd32_sendsig(sig_t, ksiginfo_t *, sigset_t *);
+static void freebsd32_sendsig(sig_t, ksiginfo_t *, sigset_t *, u_int32_t);
 
 extern const char *freebsd32_syscallnames[];
 
@@ -362,7 +362,7 @@
  * specified pc, psl.
  */
 static void
-freebsd32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+freebsd32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct proc *p;
 	struct thread *td;
@@ -427,7 +427,7 @@
 	/* Build the argument list for the signal handler. */
 	td->td_frame->a0 = sig;
 	td->td_frame->a2 = (register_t)(intptr_t)&sfp->sf_uc;
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		td->td_frame->a1 = (register_t)(intptr_t)&sfp->sf_si;
 		/* sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher; */
Index: mips/mips/pm_machdep.c
===================================================================
--- mips/mips/pm_machdep.c	(revision 274791)
+++ mips/mips/pm_machdep.c	(working copy)
@@ -81,7 +81,7 @@
  * specified pc, psl.
  */
 void
-sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct proc *p;
 	struct thread *td;
@@ -142,7 +142,7 @@
 	/* Build the argument list for the signal handler. */
 	regs->a0 = sig;
 	regs->a2 = (register_t)(intptr_t)&sfp->sf_uc;
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		regs->a1 = (register_t)(intptr_t)&sfp->sf_si;
 		/* sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher; */
Index: powerpc/powerpc/exec_machdep.c
===================================================================
--- powerpc/powerpc/exec_machdep.c	(revision 274791)
+++ powerpc/powerpc/exec_machdep.c	(working copy)
@@ -122,7 +122,7 @@
 static int	grab_mcontext(struct thread *, mcontext_t *, int);
 
 void
-sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct trapframe *tf;
 	struct sigacts *psp;
@@ -263,7 +263,7 @@
 	tf->fixreg[FIRSTARG+2] = (register_t)usfp +
 	    offsetof(struct sigframe, sf_uc);
 	#endif
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/*
 		 * Signal handler installed with SA_SIGINFO.
 		 */
Index: sparc64/sparc64/machdep.c
===================================================================
--- sparc64/sparc64/machdep.c	(revision 274791)
+++ sparc64/sparc64/machdep.c	(working copy)
@@ -596,7 +596,7 @@
 }
 
 void
-sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
+sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask, u_int32_t flags)
 {
 	struct trapframe *tf;
 	struct sigframe *sfp;
@@ -662,7 +662,7 @@
 	tf->tf_out[0] = sig;
 	tf->tf_out[2] = (register_t)&sfp->sf_uc;
 	tf->tf_out[4] = (register_t)catcher;
-	if (SIGISMEMBER(psp->ps_siginfo, sig)) {
+	if (flags & SENDSIG_SIGINFO) {
 		/* Signal handler installed with SA_SIGINFO. */
 		tf->tf_out[1] = (register_t)&sfp->sf_si;
 
Index: sys/signalvar.h
===================================================================
--- sys/signalvar.h	(revision 274791)
+++ sys/signalvar.h	(working copy)
@@ -323,6 +323,9 @@
 #define	SIGPROCMASK_PROC_LOCKED	0x0002
 #define	SIGPROCMASK_PS_LOCKED	0x0004
 
+/* Flags for sv_sendsig() */
+#define SENDSIG_SIGINFO		0x00000001	/* Handler is sa_sigaction */
+
 int	cursig(struct thread *td);
 int	sigdeferstop(void);
 void	sigallowstop(void);
@@ -337,7 +340,7 @@
 int	postsig(int sig);
 void	kern_psignal(struct proc *p, int sig);
 int	ptracestop(struct thread *td, int sig);
-void	sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *retmask);
+void	sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *retmask, u_int32_t flags);
 struct sigacts *sigacts_alloc(void);
 void	sigacts_copy(struct sigacts *dest, struct sigacts *src);
 void	sigacts_free(struct sigacts *ps);
Index: sys/sysent.h
===================================================================
--- sys/sysent.h	(revision 274791)
+++ sys/sysent.h	(working copy)
@@ -100,7 +100,7 @@
 					/* translate trap-to-signal mapping */
 	int		(*sv_fixup)(register_t **, struct image_params *);
 					/* stack fixup function */
-	void		(*sv_sendsig)(void (*)(int), struct ksiginfo *, struct __sigset *);
+	void		(*sv_sendsig)(void (*)(int), struct ksiginfo *, struct __sigset *, u_int32_t);
 			    		/* send signal */
 	char 		*sv_sigcode;	/* start of sigtramp code */
 	int 		*sv_szsigcode;	/* size of sigtramp code */