Index: sys/amd64/amd64/trap.c
===================================================================
--- sys/amd64/amd64/trap.c
+++ sys/amd64/amd64/trap.c
@@ -111,7 +111,7 @@
 void trap_check(struct trapframe *frame);
 void dblfault_handler(struct trapframe *frame);
 
-static int trap_pfault(struct trapframe *, int);
+static int trap_pfault(struct trapframe *, bool, int *, int *);
 static void trap_fatal(struct trapframe *, vm_offset_t);
 #ifdef KDTRACE_HOOKS
 static bool trap_user_dtrace(struct trapframe *,
@@ -352,40 +352,11 @@
 				return;
 
 			addr = frame->tf_addr;
-			signo = trap_pfault(frame, TRUE);
+			trap_pfault(frame, true, &signo, &ucode);
 			if (signo == -1)
 				return;
 			if (signo == 0)
 				goto userret;
-			if (signo == SIGSEGV) {
-				ucode = SEGV_MAPERR;
-			} else if (prot_fault_translation == 0) {
-				/*
-				 * Autodetect.  This check also covers
-				 * the images without the ABI-tag ELF
-				 * note.
-				 */
-				if (SV_CURPROC_ABI() == SV_ABI_FREEBSD &&
-				    p->p_osrel >= P_OSREL_SIGSEGV) {
-					signo = SIGSEGV;
-					ucode = SEGV_ACCERR;
-				} else {
-					signo = SIGBUS;
-					ucode = T_PAGEFLT;
-				}
-			} else if (prot_fault_translation == 1) {
-				/*
-				 * Always compat mode.
-				 */
-				signo = SIGBUS;
-				ucode = T_PAGEFLT;
-			} else {
-				/*
-				 * Always SIGSEGV mode.
-				 */
-				signo = SIGSEGV;
-				ucode = SEGV_ACCERR;
-			}
 			break;
 
 		case T_DIVIDE:		/* integer divide fault */
@@ -440,7 +411,7 @@
 		    ("kernel trap doesn't have ucred"));
 		switch (type) {
 		case T_PAGEFLT:			/* page fault */
-			(void) trap_pfault(frame, FALSE);
+			(void) trap_pfault(frame, false, NULL, NULL);
 			return;
 
 		case T_DNA:
@@ -713,7 +684,7 @@
 }
 
 static int
-trap_pfault(struct trapframe *frame, int usermode)
+trap_pfault(struct trapframe *frame, bool usermode, int *signo, int *ucode)
 {
 	struct thread *td;
 	struct proc *p;
@@ -776,8 +747,11 @@
 		/*
 		 * Don't allow user-mode faults in kernel address space.
 		 */
-		if (usermode)
-			return (SIGSEGV);
+		if (usermode) {
+			*signo = SIGSEGV;
+			*ucode = SEGV_ACCERR;
+			return (1);
+		}
 
 		map = kernel_map;
 	} else {
@@ -868,7 +842,40 @@
 		trap_fatal(frame, eva);
 		return (-1);
 	}
-	return ((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV);
+
+	if (rv == KERN_FAILURE) {
+		*signo = SIGSEGV;
+		*ucode = SEGV_MAPERR;
+	} else if (rv == KERN_RESOURCE_SHORTAGE) {
+		*signo = SIGBUS;
+		*ucode = BUS_ADRERR;	/* XXX any better choice ? */
+	} else if (rv == KERN_INVALID_ADDRESS) {
+		*signo = SIGBUS;
+		*ucode = BUS_OBJERR;
+	} else 	if (prot_fault_translation == 0) {
+		/*
+		 * Autodetect.  This check also covers
+		 * the images without the ABI-tag ELF
+		 * note.
+		 */
+		if (SV_CURPROC_ABI() == SV_ABI_FREEBSD &&
+		    p->p_osrel >= P_OSREL_SIGSEGV) {
+			*signo = SIGSEGV;
+			*ucode = SEGV_ACCERR;
+		} else {
+			*signo = SIGBUS;
+			*ucode = T_PAGEFLT;
+		}
+	} else if (prot_fault_translation == 1) {
+		/* Always compat mode. */
+		*signo = SIGBUS;
+		*ucode = T_PAGEFLT;
+	} else {
+		/* Always SIGSEGV mode. */
+		*signo = SIGSEGV;
+		*ucode = SEGV_ACCERR;
+	}
+	return (1);
 }
 
 static void
Index: sys/vm/vm_fault.c
===================================================================
--- sys/vm/vm_fault.c
+++ sys/vm/vm_fault.c
@@ -562,6 +562,11 @@
 #endif
 	result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags,
 	    NULL);
+	KASSERT(result == KERN_SUCCESS || result == KERN_FAILURE ||
+	    result == KERN_INVALID_ADDRESS ||
+	    result == KERN_RESOURCE_SHORTAGE ||
+	    result == KERN_PROTECTION_FAILURE,
+	    ("Unknown Mach error %d from vm_fault_hold()", result));
 #ifdef KTRACE
 	if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND))
 		ktrfaultend(result);
@@ -787,7 +792,7 @@
 		    fs.object == fs.first_object) {
 			if (fs.pindex >= fs.object->size) {
 				unlock_and_deallocate(&fs);
-				return (KERN_PROTECTION_FAILURE);
+				return (KERN_INVALID_ADDRESS);
 			}
 
 			if (fs.object == fs.first_object &&