ktrexec
ktrexec(p, KTR_EXECARGS, argp, dp - argp);
ktrexec(p, KTR_EXECENV, env_start, dp - env_start);
void ktrexec(struct proc *, int, const char *, ssize_t);
static void ktrexec(const char*, size_t);
ktrexec(m, ktrlen);