tools: bpftool: add -d option to get debug output from libbpf

libbpf has three levels of priority for output messages: warn, info,
debug. By default, debug output is not printed to the console.

Add a new "--debug" (short name: "-d") option to bpftool to print libbpf
logs for all three levels.

Internally, we simply use the function provided by libbpf to replace the
default printing function by one that prints logs regardless of their
level.

v2:
- Remove the possibility to select the log-levels to use (v1 offered a
  combination of "warn", "info" and "debug").
- Rename option and offer a short name: -d|--debug.
- Add option description to all bpftool manual pages (instead of
  bpftool-prog.rst only), as all commands use libbpf.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
index e8118544d118..9a92614569e6 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
@@ -174,6 +174,10 @@ OPTIONS
 		  Do not automatically attempt to mount any virtual file system
 		  (such as tracefs or BPF virtual file system) when necessary.
 
+	-d, --debug
+		  Print all logs available from libbpf, including debug-level
+		  information.
+
 EXAMPLES
 ========
 **# bpftool prog show**