+ /*
+ * Do this negation as unsigned arithmetic; that's
+ * what modern BPF engines do, and it guarantees
+ * that all possible values can be negated. (Yeah,
+ * negating 0x80000000, the minimum signed 32-bit
+ * two's-complement value, results in 0x80000000,
+ * so it's still negative, but we *should* be doing
+ * all unsigned arithmetic here, to match what
+ * modern BPF engines do.)
+ *
+ * Express it as 0U - (unsigned value) so that we
+ * don't get compiler warnings about negating an
+ * unsigned value and don't get UBSan warnings
+ * about the result of negating 0x80000000 being
+ * undefined.
+ */
+ s->k = 0U - opt_state->vmap[val[A_ATOM]].const_val;