Index: sys/mips/include/proc.h
===================================================================
--- sys/mips/include/proc.h
+++ sys/mips/include/proc.h
@@ -81,11 +81,11 @@
 	size_t		md_tls_tcb_offset;	/* TCB offset */
 };
 
+#define	MAXARGS		8
 struct syscall_args {
 	u_int code;
 	struct sysent *callp;
-	register_t args[8];
-	struct trapframe *trapframe;
+	register_t args[MAXARGS];
 };
 
 #ifdef __mips_n64
Index: sys/mips/mips/trap.c
===================================================================
--- sys/mips/mips/trap.c
+++ sys/mips/mips/trap.c
@@ -349,9 +349,9 @@
 	bzero(sa->args, sizeof(sa->args));
 
 	/* compute next PC after syscall instruction */
-	td->td_pcb->pcb_tpc = sa->trapframe->pc; /* Remember if restart */
-	if (DELAYBRANCH(sa->trapframe->cause))	 /* Check BD bit */
-		locr0->pc = MipsEmulateBranch(locr0, sa->trapframe->pc, 0, 0);
+	td->td_pcb->pcb_tpc = locr0->pc; /* Remember if restart */
+	if (DELAYBRANCH(locr0->cause))	 /* Check BD bit */
+		locr0->pc = MipsEmulateBranch(locr0, locr0->pc, 0, 0);
 	else
 		locr0->pc += sizeof(int);
 	sa->code = locr0->v0;
@@ -781,7 +781,6 @@
 
 	case T_SYSCALL + T_USER:
 		{
-			td->td_sa.trapframe = trapframe;
 			syscallenter(td);
 
 #if !defined(SMP) && (defined(DDB) || defined(DEBUG))
Index: sys/riscv/riscv/trap.c
===================================================================
--- sys/riscv/riscv/trap.c
+++ sys/riscv/riscv/trap.c
@@ -46,6 +46,7 @@
 #include <sys/ptrace.h>
 #include <sys/syscall.h>
 #include <sys/sysent.h>
+#include <sys/sysproto.h>
 #ifdef KDB
 #include <sys/kdb.h>
 #endif
@@ -106,12 +107,6 @@
 
 	sa->code = td->td_frame->tf_t[0];
 
-	if (__predict_false(sa->code == SYS_syscall || sa->code == SYS___syscall)) {
-		sa->code = *ap++;
-	} else {
-		*dst_ap++ = *ap++;
-	}
-
 	if (__predict_false(sa->code >= p->p_sysent->sv_size))
 		sa->callp = &p->p_sysent->sv_table[0];
 	else
@@ -120,7 +115,13 @@
 	KASSERT(sa->callp->sy_narg <= nitems(sa->args),
 	    ("Syscall %d takes too many arguments", sa->code));
 
-	memcpy(dst_ap, ap, (NARGREG - 1) * sizeof(register_t));
+	if (__predict_false(sa->callp->sy_call == (sy_call_t *)nosys) &&
+	    (sa->code == SYS_syscall || sa->code == SYS___syscall)) {
+		sa->code = *ap++;
+		memcpy(dst_ap, ap, (NARGREG - 1) * sizeof(register_t));
+	} else {
+		memcpy(dst_ap, ap, NARGREG * sizeof(register_t));
+	}
 
 	td->td_retval[0] = 0;
 	td->td_retval[1] = 0;