Loading of bpf fails with invalid argument #12
Description
Latest (c126589) libbpf-bootstrap gives errors when loading on Debian testing x86_64 with kernel 5.10.17. Actually, already the compilation step is a bit fishy, as it says:
libbpf-bootstrap/src(master)$ make
MKDIR .output
MKDIR .output/libbpf
LIB libbpf.a
MKDIR staticobjs
CC bpf.o
CC btf.o
CC libbpf.o
CC libbpf_errno.o
CC netlink.o
CC nlattr.o
CC str_error.o
CC libbpf_probes.o
CC bpf_prog_linfo.o
CC xsk.o
CC btf_dump.o
CC hashmap.o
CC ringbuf.o
AR libbpf.a
INSTALL bpf.h libbpf.h btf.h xsk.h libbpf_util.h bpf_helpers.h bpf_helper_defs.h bpf_tracing.h bpf_endian.h bpf_core_read.h libbpf_common.h
INSTALL libbpf.pc
INSTALL libbpf.a
BPF .output/minimal.bpf.o
GEN-SKEL .output/minimal.skel.h
libbpf: elf: skipping unrecognized data section(5) .rodata.str1.1
CC .output/minimal.o
BINARY minimal
BPF .output/bootstrap.bpf.o
GEN-SKEL .output/bootstrap.skel.h
CC .output/bootstrap.o
BINARY bootstrap
BPF .output/uprobe.bpf.o
GEN-SKEL .output/uprobe.skel.h
libbpf: elf: skipping unrecognized data section(5) .rodata.str1.1
CC .output/uprobe.o
BINARY uprobe
BPF .output/kprobe.bpf.o
GEN-SKEL .output/kprobe.skel.h
libbpf: elf: skipping unrecognized data section(5) .rodata.str1.1
CC .output/kprobe.o
BINARY kprobe
BPF .output/fentry.bpf.o
GEN-SKEL .output/fentry.skel.h
libbpf: elf: skipping unrecognized data section(5) .rodata.str1.1
CC .output/fentry.o
BINARY fentry
In all three cases of GEN-SKEL, the output happens in response to
...
llvm-strip -g .output/minimal.bpf.o # strip useless DWARF info
libbpf-bootstrap/tools/bpftool gen skeleton .output/minimal.bpf.o > .output/minimal.skel.h
libbpf: elf: skipping unrecognized data section(5) .rodata.str1.1
...
But then running 'minimal' fails with
libbpf-bootstrap/src(master)# ./minimal
libbpf: loading object 'minimal_bpf' from buffer
libbpf: elf: section(2) tp/syscalls/sys_enter_write, size 192, link 0, flags 6, type=1
libbpf: sec 'tp/syscalls/sys_enter_write': found program 'handle_tp' at insn offset 0 (0 bytes), code size 24 insns (192 bytes)
libbpf: elf: section(3) license, size 13, link 0, flags 3, type=1
libbpf: license of minimal_bpf is Dual BSD/GPL
libbpf: elf: section(4) .bss, size 4, link 0, flags 3, type=8
libbpf: elf: section(5) .rodata.str1.1, size 28, link 0, flags 32, type=1
libbpf: elf: skipping unrecognized data section(5) .rodata.str1.1
libbpf: elf: section(6) .BTF, size 494, link 0, flags 0, type=1
libbpf: elf: section(7) .BTF.ext, size 160, link 0, flags 0, type=1
libbpf: elf: section(8) .symtab, size 144, link 13, flags 0, type=2
libbpf: elf: section(9) .reltp/syscalls/sys_enter_write, size 16, link 8, flags 0, type=9
libbpf: looking for externs among 6 symbols...
libbpf: collected 0 externs total
libbpf: map 'minimal_.bss' (global data): at sec_idx 4, offset 0, flags 400.
libbpf: map 0 is "minimal_.bss"
libbpf: sec '.reltp/syscalls/sys_enter_write': collecting relocation for section(2) 'tp/syscalls/sys_enter_write'
libbpf: sec '.reltp/syscalls/sys_enter_write': relo #0: insn #2 against 'my_pid'
libbpf: prog 'handle_tp': found data map 0 (minimal_.bss, sec 4, off 0) for insn 2
libbpf: map 'minimal_.bss': created successfully, fd=4
libbpf: load bpf program failed: Invalid argument
libbpf: failed to load program 'handle_tp'
libbpf: failed to load object 'minimal_bpf'
libbpf: failed to load BPF skeleton 'minimal_bpf': -22
Failed to load and verify BPF skeleton
The other programs also fail at the exact same point when loading eBPF programs and with the same error. Might this be an issue with the kernel (v5.10.17, compile by me), clang/llvm (Debian testing versions 11.0.1-2 and 11.0.1), Debian (testing), libbpf-bootstrap (c126589) or something else?