Index: head/sys/kern/kern_thread.c
===================================================================
--- head/sys/kern/kern_thread.c
+++ head/sys/kern/kern_thread.c
@@ -84,7 +84,7 @@
     "struct thread KBI td_pflags");
 _Static_assert(offsetof(struct thread, td_frame) == 0x478,
     "struct thread KBI td_frame");
-_Static_assert(offsetof(struct thread, td_emuldata) == 0x548,
+_Static_assert(offsetof(struct thread, td_emuldata) == 0x540,
     "struct thread KBI td_emuldata");
 _Static_assert(offsetof(struct proc, p_flag) == 0xb0,
     "struct proc KBI p_flag");
@@ -102,7 +102,7 @@
     "struct thread KBI td_flags");
 _Static_assert(offsetof(struct thread, td_pflags) == 0xa0,
     "struct thread KBI td_pflags");
-_Static_assert(offsetof(struct thread, td_frame) == 0x2ec,
+_Static_assert(offsetof(struct thread, td_frame) == 0x2f0,
     "struct thread KBI td_frame");
 _Static_assert(offsetof(struct thread, td_emuldata) == 0x338,
     "struct thread KBI td_emuldata");
Index: head/sys/kern/subr_syscall.c
===================================================================
--- head/sys/kern/subr_syscall.c
+++ head/sys/kern/subr_syscall.c
@@ -85,8 +85,10 @@
 	    (uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0],
 	    "arg1:%p", sa->args[1], "arg2:%p", sa->args[2]);
 
-	if (error != 0)
+	if (error != 0) {
+		td->td_errno = error;
 		goto retval;
+	}
 
 	STOPEVENT(p, S_SCE, sa->narg);
 	if ((p->p_flag & P_TRACED) != 0) {
@@ -105,8 +107,10 @@
 		if (KTRPOINT(td, KTR_SYSCALL))
 			ktrsyscall(sa->code, sa->narg, sa->args);
 #endif
-		if (error != 0)
+		if (error != 0) {
+			td->td_errno = error;
 			goto retval;
+		}
 	}
 
 #ifdef CAPABILITY_MODE
@@ -116,14 +120,16 @@
 	 */
 	if (IN_CAPABILITY_MODE(td) &&
 	    !(sa->callp->sy_flags & SYF_CAPENABLED)) {
-		error = ECAPMODE;
+		td->td_errno = error = ECAPMODE;
 		goto retval;
 	}
 #endif
 
 	error = syscall_thread_enter(td, sa->callp);
-	if (error != 0)
+	if (error != 0) {
+		td->td_errno = error;
 		goto retval;
+	}
 
 #ifdef KDTRACE_HOOKS
 	/* Give the syscall:::entry DTrace probe a chance to fire. */
@@ -131,6 +137,9 @@
 		(*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0);
 #endif
 
+	/* Let system calls set td_errno directly. */
+	td->td_pflags &= ~TDP_NERRNO;
+
 	AUDIT_SYSCALL_ENTER(sa->code, td);
 	error = (sa->callp->sy_call)(td, sa->args);
 	AUDIT_SYSCALL_EXIT(error, td);
@@ -162,12 +171,12 @@
 }
 
 static inline void
-syscallret(struct thread *td, int error)
+syscallret(struct thread *td, int error __unused)
 {
 	struct proc *p;
 	struct syscall_args *sa;
 	ksiginfo_t ksi;
-	int traced, error1;
+	int traced;
 
 	KASSERT((td->td_pflags & TDP_FORKING) == 0,
 	    ("fork() did not clear TDP_FORKING upon completion"));
@@ -176,12 +185,10 @@
 	sa = &td->td_sa;
 	if ((trap_enotcap || (p->p_flag2 & P2_TRAPCAP) != 0) &&
 	    IN_CAPABILITY_MODE(td)) {
-		error1 = (td->td_pflags & TDP_NERRNO) == 0 ? error :
-		    td->td_errno;
-		if (error1 == ENOTCAPABLE || error1 == ECAPMODE) {
+		if (td->td_errno == ENOTCAPABLE || td->td_errno == ECAPMODE) {
 			ksiginfo_init_trap(&ksi);
 			ksi.ksi_signo = SIGTRAP;
-			ksi.ksi_errno = error1;
+			ksi.ksi_errno = td->td_errno;
 			ksi.ksi_code = TRAP_CAP;
 			trapsignal(td, &ksi);
 		}
@@ -194,11 +201,9 @@
 
 #ifdef KTRACE
 	if (KTRPOINT(td, KTR_SYSRET)) {
-		ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ?
-		    error : td->td_errno, td->td_retval[0]);
+		ktrsysret(sa->code, td->td_errno, td->td_retval[0]);
 	}
 #endif
-	td->td_pflags &= ~TDP_NERRNO;
 
 	if (p->p_flag & P_TRACED) {
 		traced = 1;
Index: head/sys/sys/proc.h
===================================================================
--- head/sys/sys/proc.h
+++ head/sys/sys/proc.h
@@ -303,6 +303,7 @@
 	void		*td_su;		/* (k) FFS SU private */
 	sbintime_t	td_sleeptimo;	/* (t) Sleep timeout. */
 	int		td_rtcgen;	/* (s) rtc_generation of abs. sleep */
+	int		td_errno;	/* (k) Error from last syscall. */
 	size_t		td_vslock_sz;	/* (k) amount of vslock-ed space */
 	struct kcov_info *td_kcov_info;	/* (*) Kernel code coverage data */
 #define	td_endzero td_sigmask
@@ -353,8 +354,6 @@
 	struct kaudit_record	*td_ar;	/* (k) Active audit record, if any. */
 	struct lpohead	td_lprof[2];	/* (a) lock profiling objects. */
 	struct kdtrace_thread	*td_dtrace; /* (*) DTrace-specific data. */
-	int		td_errno;	/* Error returned by last syscall. */
-	/* LP64 hole */
 	struct vnet	*td_vnet;	/* (k) Effective vnet. */
 	const char	*td_vnet_lpush;	/* (k) Debugging vnet push / pop. */
 	struct trapframe *td_intr_frame;/* (k) Frame of the current irq */