In commit 4a3d6c6a6e ("libbpf: Reduce log level for custom section
names"), log level for messages for libbpf_attach_type_by_name() and
libbpf_prog_type_by_name() was downgraded from "info" to "debug". The
latter function, in particular, is used by bpftool when attempting to
load programs, and this change caused bpftool to exit with no hint or
error message when it fails to detect the type of the program to load
(unless "-d" option was provided).
To help users understand why bpftool fails to load the program, let's do
a second run of the function with log level in "debug" mode in case of
failure.
Before:
# bpftool prog load sample_ret0.o /sys/fs/bpf/sample_ret0
# echo $?
255
Or really verbose with -d flag:
# bpftool -d prog load sample_ret0.o /sys/fs/bpf/sample_ret0
libbpf: loading sample_ret0.o
libbpf: section(1) .strtab, size 134, link 0, flags 0, type=3
libbpf: skip section(1) .strtab
libbpf: section(2) .text, size 16, link 0, flags 6, type=1
libbpf: found program .text
libbpf: section(3) .debug_abbrev, size 55, link 0, flags 0, type=1
libbpf: skip section(3) .debug_abbrev
libbpf: section(4) .debug_info, size 75, link 0, flags 0, type=1
libbpf: skip section(4) .debug_info
libbpf: section(5) .rel.debug_info, size 32, link 14, flags 0, type=9
libbpf: skip relo .rel.debug_info(5) for section(4)
libbpf: section(6) .debug_str, size 150, link 0, flags 30, type=1
libbpf: skip section(6) .debug_str
libbpf: section(7) .BTF, size 155, link 0, flags 0, type=1
libbpf: section(8) .BTF.ext, size 80, link 0, flags 0, type=1
libbpf: section(9) .rel.BTF.ext, size 32, link 14, flags 0, type=9
libbpf: skip relo .rel.BTF.ext(9) for section(8)
libbpf: section(10) .debug_frame, size 40, link 0, flags 0, type=1
libbpf: skip section(10) .debug_frame
libbpf: section(11) .rel.debug_frame, size 16, link 14, flags 0, type=9
libbpf: skip relo .rel.debug_frame(11) for section(10)
libbpf: section(12) .debug_line, size 74, link 0, flags 0, type=1
libbpf: skip section(12) .debug_line
libbpf: section(13) .rel.debug_line, size 16, link 14, flags 0, type=9
libbpf: skip relo .rel.debug_line(13) for section(12)
libbpf: section(14) .symtab, size 96, link 1, flags 0, type=2
libbpf: looking for externs among 4 symbols...
libbpf: collected 0 externs total
libbpf: failed to guess program type from ELF section '.text'
libbpf: supported section(type) names are: socket sk_reuseport kprobe/ [...]
After:
# bpftool prog load sample_ret0.o /sys/fs/bpf/sample_ret0
libbpf: failed to guess program type from ELF section '.text'
libbpf: supported section(type) names are: socket sk_reuseport kprobe/ [...]
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200311021205.9755-1-quentin@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
6ae32b29c0