D26528.id77412.diff
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	Index: sys/riscv/riscv/trap.c
	===================================================================
	--- sys/riscv/riscv/trap.c
	+++ sys/riscv/riscv/trap.c
	@@ -99,28 +99,33 @@
	register_t *ap;
	struct syscall_args *sa;
	int nap;
	+ bool shift_args;

	- nap = NARGREG;
	p = td->td_proc;
	sa = &td->td_sa;
	ap = &td->td_frame->tf_a[0];

	sa->code = td->td_frame->tf_t[0];

	- if (sa->code == SYS_syscall \|\| sa->code == SYS___syscall) {
	+ if (__predict_false(sa->code == SYS_syscall \|\| sa->code == SYS___syscall)) {
	sa->code = *ap++;
	- nap--;
	+ shift_args = true;
	+ } else {
	+ shift_args = false;
	}

	- if (sa->code >= p->p_sysent->sv_size)
	+ if (__predict_false(sa->code >= p->p_sysent->sv_size))
	sa->callp = &p->p_sysent->sv_table[0];
	else
	sa->callp = &p->p_sysent->sv_table[sa->code];

	sa->narg = sa->callp->sy_narg;
	- memcpy(sa->args, ap, nap * sizeof(register_t));
	- if (sa->narg > nap)
	- panic("TODO: Could we have more then %d args?", NARGREG);
	+ KASSERT(sa->callp->sy_narg <= nitems(sa->args), ("Too many syscall arguments!"));
	+
	+ if (__predict_false(shift_args))
	+ memcpy(sa->args, ap, (NARGREG - 1) * sizeof(register_t));
	+ else
	+ memcpy(sa->args, ap, NARGREG * sizeof(register_t));

	td->td_retval[0] = 0;
	td->td_retval[1] = 0;