Per discussion at:

https://lore.kernel.org/bpf/c964892195a6b91d20a67691448567ef528ffa6d.camel@linux.ibm.com/T/#t (local)

...this was originally introduced as a warning due to concerns about
breaking existing code, but a hard error probably makes more sense,
especially given that concerns about breakage were only speculation.
---
 tools/bpf/bpf_exp.y | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/bpf/bpf_exp.y b/tools/bpf/bpf_exp.y
index 8d48e896be50..8d03e5245da5 100644
--- a/tools/bpf/bpf_exp.y
+++ b/tools/bpf/bpf_exp.y

@@ -549,9 +549,11 @@ static uint8_t bpf_encode_jt_jf_offset(int off,

int i)
 {
        int delta = off - i - 1;
 
-       if (delta < 0 || delta > 255)
-               fprintf(stderr, "warning: insn #%d jumps to insn #%d, "
+       if (delta < 0 || delta > 255) {
+               fprintf(stderr, "error: insn #%d jumps to insn #%d, "
                                "which is out of range\n", i, off);
+               exit(1);
+       }
        return (uint8_t) delta;
 }