from bpftool github repo issue [0], when Linux distribution kernel.kptr_restrict is set to 2, bpftool prog dump jited returns "no instructions returned", this message can be puzzling to bpftool users who is not familiar with kernel BPF internal, so add small hint for bpftool users to check kernel.kptr_restrict setting. Set kernel.kptr_restrict to expose kernel address to allow bpftool prog dump jited to dump the jited bpf program instructions. [0]: https://github.com/libbpf/bpftool/issues/184 Signed-off-by: Vincent Li <vincent.mc.li@xxxxxxxxx. --- tools/bpf/bpftool/prog.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index 9722d841abc0..cf18c3879680 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -714,7 +714,7 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode, if (mode == DUMP_JITED) { if (info->jited_prog_len == 0 || !info->jited_prog_insns) { - p_info("no instructions returned"); + p_err("error retrieving jit dump: no instructions returned or kernel.kptr_restrict set?"); return -1; } buf = u64_to_ptr(info->jited_prog_insns); -- 2.38.1
