tree d7393cd6ba68b08787e37d9414c32a9ce10fbdf4
parent 73a4f0407e67cdfdf55dd94f573ed4ee2d0d62fe
author Tobias Klauser <tklauser@distanz.ch> 1590414861 +0200
committer Alexei Starovoitov <ast@kernel.org> 1591047499 -0700

tools, bpftool: Print correct error message when failing to load BTF

btf__parse_raw and btf__parse_elf return negative error numbers wrapped
in an ERR_PTR, so the extracted value needs to be negated before passing
them to strerror which expects a positive error number.

Before:
  Error: failed to load BTF from .../vmlinux: Unknown error -2

After:
  Error: failed to load BTF from .../vmlinux: No such file or directory

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200525135421.4154-1-tklauser@distanz.ch
Signed-off-by: Alexei Starovoitov <ast@kernel.org>