> On Sat, Jul 9, 2022 at 2:32 PM James Hilliard <james.hilliard1@xxxxxxxxx> wrote: >> >> On Sat, Jul 9, 2022 at 2:21 PM Jose E. Marchesi >> <jose.marchesi@xxxxxxxxxx> wrote: >> > >> > >> > > On Sat, Jul 9, 2022 at 11:24 AM Jose E. Marchesi >> > > <jose.marchesi@xxxxxxxxxx> wrote: >> > >> >> > >> >> > >> > On Fri, Jul 8, 2022 at 12:33 PM Jose E. Marchesi >> > >> > <jose.marchesi@xxxxxxxxxx> wrote: >> > >> >> >> > >> >> >> > >> >> >> On Wed, Jul 6, 2022 at 10:13 AM James Hilliard >> > >> >> >> <james.hilliard1@xxxxxxxxx> wrote: >> > >> >> >>> >> > >> >> >>> Note I'm testing with the following patches: >> > >> >> >>> https://lore.kernel.org/bpf/20220706111839.1247911-1-james.hilliard1@xxxxxxxxx/ >> > >> >> >>> https://lore.kernel.org/bpf/20220706140623.2917858-1-james.hilliard1@xxxxxxxxx/ >> > >> >> >>> >> > >> >> >>> It would appear there's some compatibility issues with bpftool gen and >> > >> >> >>> GCC, not sure what side though is wrong here: >> > >> >> >>> /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool >> > >> >> >>> gen object src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o >> > >> >> >>> src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o >> > >> >> >>> libbpf: failed to find BTF info for global/extern symbol 'sd_restrictif_i' >> > >> >> >>> Error: failed to link >> > >> >> >>> 'src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o': >> > >> >> >>> Unknown error -2 (-2) >> > >> >> >>> >> > >> >> >>> Relevant difference seems to be this: >> > >> >> >>> GCC: >> > >> >> >>> [55] FUNC 'sd_restrictif_i' type_id=47 linkage=static >> > >> >> >>> Clang: >> > >> >> >>> [27] FUNC 'sd_restrictif_i' type_id=26 linkage=global >> > >> >> > >> > >> >> > For functions GCC generates a BTF_KIND_FUNC entry, which has no linkage >> > >> >> > information, or so we thought: I just looked at bpftool/btf.c and I >> > >> >> > found the linkage info for function types is expected to be encoded in >> > >> >> > the vlen field of BTF_KIND_FUNC entries (why not adding a btf_func >> > >> >> > instead???) which is surprising to say the least. >> > >> >> > >> > >> >> > We are changing GCC to encode the linkage info in vlen for these types. >> > >> >> > Thanks for reporting this. >> > >> >> >> > >> >> Patch sent to GCC upstream: >> > >> >> https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598090.html >> > >> > >> > >> > I applied that patch on top of GCC 12.1.0 and it appears to fix the >> > >> > bpftool gen object bug. >> > >> > >> > >> > I am however now hitting a different error during skeleton generation: >> > >> > /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool >> > >> > gen skeleton src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o >> > >> > libbpf: elf: skipping unrecognized data section(9) .comment >> > >> > libbpf: failed to alloc map 'restrict.bss' content buffer: -22 >> > >> > Error: failed to open BPF object file: Invalid argument >> > >> >> > >> What is the size of the .bss section in the object file? Try with: >> > >> >> > >> $ size restrict-ifaces.bpf.o >> > > >> > > $ size > output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o >> > > text data bss dec hex filename >> > > 386 25 0 411 19b >> > > output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o >> > >> > Right, so the .bss section is empty. I see a `const volatile unsigned >> > char is_allow_list = 0;' in restrict-ifaces.bpf.c, but that goes to >> > .data and not to .bss, as expected. >> > >> > If you build restrict-ifaces.bpf.o with LLVM, is the bss still empty? I >> > don't think the code in libbpf.c even checks for this eventuality... >> >> LLVM version(which skeleton generation works with): >> $ size restrict-ifaces.bpf.o >> text data bss dec hex filename >> 323 24 0 347 15b restrict-ifaces.bpf.o >> >> $ /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool >> btf dump file restrict-ifaces.bpf.o format raw >> [1] PTR '(anon)' type_id=3 >> [2] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED >> [3] ARRAY '(anon)' type_id=2 index_type_id=4 nr_elems=1 >> [4] INT '__ARRAY_SIZE_TYPE__' size=4 bits_offset=0 nr_bits=32 encoding=(none) >> [5] PTR '(anon)' type_id=6 >> [6] TYPEDEF '__u32' type_id=7 >> [7] INT 'unsigned int' size=4 bits_offset=0 nr_bits=32 encoding=(none) >> [8] PTR '(anon)' type_id=9 >> [9] TYPEDEF '__u8' type_id=10 >> [10] INT 'unsigned char' size=1 bits_offset=0 nr_bits=8 encoding=(none) >> [11] STRUCT '(anon)' size=24 vlen=3 >> 'type' type_id=1 bits_offset=0 >> 'key' type_id=5 bits_offset=64 >> 'value' type_id=8 bits_offset=128 >> [12] VAR 'sd_restrictif' type_id=11, linkage=global >> [13] PTR '(anon)' type_id=14 >> [14] CONST '(anon)' type_id=15 >> [15] STRUCT '__sk_buff' size=192 vlen=33 >> 'len' type_id=6 bits_offset=0 >> 'pkt_type' type_id=6 bits_offset=32 >> 'mark' type_id=6 bits_offset=64 >> 'queue_mapping' type_id=6 bits_offset=96 >> 'protocol' type_id=6 bits_offset=128 >> 'vlan_present' type_id=6 bits_offset=160 >> 'vlan_tci' type_id=6 bits_offset=192 >> 'vlan_proto' type_id=6 bits_offset=224 >> 'priority' type_id=6 bits_offset=256 >> 'ingress_ifindex' type_id=6 bits_offset=288 >> 'ifindex' type_id=6 bits_offset=320 >> 'tc_index' type_id=6 bits_offset=352 >> 'cb' type_id=16 bits_offset=384 >> 'hash' type_id=6 bits_offset=544 >> 'tc_classid' type_id=6 bits_offset=576 >> 'data' type_id=6 bits_offset=608 >> 'data_end' type_id=6 bits_offset=640 >> 'napi_id' type_id=6 bits_offset=672 >> 'family' type_id=6 bits_offset=704 >> 'remote_ip4' type_id=6 bits_offset=736 >> 'local_ip4' type_id=6 bits_offset=768 >> 'remote_ip6' type_id=17 bits_offset=800 >> 'local_ip6' type_id=17 bits_offset=928 >> 'remote_port' type_id=6 bits_offset=1056 >> 'local_port' type_id=6 bits_offset=1088 >> 'data_meta' type_id=6 bits_offset=1120 >> '(anon)' type_id=18 bits_offset=1152 >> 'tstamp' type_id=20 bits_offset=1216 >> 'wire_len' type_id=6 bits_offset=1280 >> 'gso_segs' type_id=6 bits_offset=1312 >> '(anon)' type_id=22 bits_offset=1344 >> 'gso_size' type_id=6 bits_offset=1408 >> 'hwtstamp' type_id=20 bits_offset=1472 >> [16] ARRAY '(anon)' type_id=6 index_type_id=4 nr_elems=5 >> [17] ARRAY '(anon)' type_id=6 index_type_id=4 nr_elems=4 >> [18] UNION '(anon)' size=8 vlen=1 >> 'flow_keys' type_id=19 bits_offset=0 >> [19] PTR '(anon)' type_id=34 >> [20] TYPEDEF '__u64' type_id=21 >> [21] INT 'unsigned long long' size=8 bits_offset=0 nr_bits=64 encoding=(none) >> [22] UNION '(anon)' size=8 vlen=1 >> 'sk' type_id=23 bits_offset=0 >> [23] PTR '(anon)' type_id=35 >> [24] FUNC_PROTO '(anon)' ret_type_id=2 vlen=1 >> 'sk' type_id=13 >> [25] FUNC 'sd_restrictif_e' type_id=24 linkage=global >> [26] FUNC 'sd_restrictif_i' type_id=24 linkage=global >> [27] CONST '(anon)' type_id=28 >> [28] VOLATILE '(anon)' type_id=9 >> [29] VAR 'is_allow_list' type_id=27, linkage=global >> [30] CONST '(anon)' type_id=31 >> [31] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED >> [32] ARRAY '(anon)' type_id=30 index_type_id=4 nr_elems=18 >> [33] VAR '_license' type_id=32, linkage=static >> [34] FWD 'bpf_flow_keys' fwd_kind=struct >> [35] FWD 'bpf_sock' fwd_kind=struct >> [36] DATASEC '.rodata' size=1 vlen=1 >> type_id=29 offset=0 size=1 (VAR 'is_allow_list') >> [37] DATASEC 'license' size=18 vlen=1 >> type_id=33 offset=0 size=18 (VAR '_license') >> [38] DATASEC '.maps' size=24 vlen=1 >> type_id=12 offset=0 size=24 (VAR 'sd_restrictif') >> > > Skeleton generation debug output for GCC(failing) and LLVM(working) > which may be helpful: Indeed it was helpful :) The GNU assembler generates an empty .bss section. This is a well established behavior in GAS that happens in all supported targets. The LLVM assembler doesn't generate an empty .bss section. bpftool chokes on the empty .bss section. In this case I would suggest to fix bpf_object__init_global_data_maps in order to skip empty sections. Something like this: diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index e89cc9c885b3..e3a6808f0bb6 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -1591,6 +1591,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj) for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) { sec_desc = &obj->efile.secs[sec_idx]; + /* Skip empty sections. */ + if (sec_desc->data->d_size == 0) + continue; + switch (sec_desc->sec_type) { case SEC_DATA: sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx)); > GCC: > $ /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool > --debug gen skeleton > output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o > libbpf: loading object 'restrict_ifaces_bpf' from buffer > libbpf: elf: section(2) .symtab, size 336, link 1, flags 0, type=2 > libbpf: elf: section(3) .data, size 1, link 0, flags 3, type=1 > libbpf: elf: section(4) .bss, size 0, link 0, flags 3, type=8 > libbpf: elf: section(5) cgroup_skb/egress, size 184, link 0, flags 6, type=1 > libbpf: sec 'cgroup_skb/egress': found program 'sd_restrictif_e' at > insn offset 0 (0 bytes), code size 23 insns (184 bytes) > libbpf: elf: section(6) cgroup_skb/ingress, size 184, link 0, flags 6, type=1 > libbpf: sec 'cgroup_skb/ingress': found program 'sd_restrictif_i' at > insn offset 0 (0 bytes), code size 23 insns (184 bytes) > libbpf: elf: section(7) license, size 18, link 0, flags 2, type=1 > libbpf: license of restrict_ifaces_bpf is LGPL-2.1-or-later > libbpf: elf: section(8) .maps, size 24, link 0, flags 3, type=1 > libbpf: elf: section(9) .comment, size 49, link 0, flags 30, type=1 > libbpf: elf: skipping unrecognized data section(9) .comment > libbpf: elf: section(10) .relcgroup_skb/egress, size 32, link 2, flags > 40, type=9 > libbpf: elf: section(11) .relcgroup_skb/ingress, size 32, link 2, > flags 40, type=9 > libbpf: elf: section(12) .BTF, size 3606, link 0, flags 0, type=1 > libbpf: looking for externs among 14 symbols... > libbpf: collected 0 externs total > libbpf: map 'sd_restrictif': at sec_idx 8, offset 0. > libbpf: map 'sd_restrictif': found type = 1. > libbpf: map 'sd_restrictif': found key [12], sz = 4. > libbpf: map 'sd_restrictif': found value [3], sz = 1. > libbpf: map 'restrict.data' (global data): at sec_idx 3, offset 0, flags 400. > libbpf: map 1 is "restrict.data" > libbpf: map 'restrict.bss' (global data): at sec_idx 4, offset 0, flags 400. > libbpf: failed to alloc map 'restrict.bss' content buffer: -22 > Error: failed to open BPF object file: Invalid argument > > LLVM: > $ /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool > --debug gen skeleton restrict-ifaces.bpf.o > libbpf: loading object 'restrict_ifaces_bpf' from buffer > libbpf: elf: section(2) .symtab, size 384, link 1, flags 0, type=2 > libbpf: elf: section(3) cgroup_skb/egress, size 152, link 0, flags 6, type=1 > libbpf: sec 'cgroup_skb/egress': found program 'sd_restrictif_e' at > insn offset 0 (0 bytes), code size 19 insns (152 bytes) > libbpf: elf: section(4) cgroup_skb/ingress, size 152, link 0, flags 6, type=1 > libbpf: sec 'cgroup_skb/ingress': found program 'sd_restrictif_i' at > insn offset 0 (0 bytes), code size 19 insns (152 bytes) > libbpf: elf: section(5) .rodata, size 1, link 0, flags 2, type=1 > libbpf: elf: section(6) license, size 18, link 0, flags 2, type=1 > libbpf: license of restrict_ifaces_bpf is LGPL-2.1-or-later > libbpf: elf: section(7) .maps, size 24, link 0, flags 3, type=1 > libbpf: elf: section(8) .relcgroup_skb/egress, size 32, link 2, flags 40, type=9 > libbpf: elf: section(9) .relcgroup_skb/ingress, size 32, link 2, flags > 40, type=9 > libbpf: elf: section(10) .BTF, size 1988, link 0, flags 0, type=1 > libbpf: elf: section(11) .BTF.ext, size 376, link 0, flags 0, type=1 > libbpf: looking for externs among 16 symbols... > libbpf: collected 0 externs total > libbpf: map 'sd_restrictif': at sec_idx 7, offset 0. > libbpf: map 'sd_restrictif': found type = 1. > libbpf: map 'sd_restrictif': found key [6], sz = 4. > libbpf: map 'sd_restrictif': found value [9], sz = 1. > libbpf: map 'restrict.rodata' (global data): at sec_idx 5, offset 0, flags 480. > libbpf: map 1 is "restrict.rodata" > libbpf: sec '.relcgroup_skb/egress': collecting relocation for > section(3) 'cgroup_skb/egress' > libbpf: sec '.relcgroup_skb/egress': relo #0: insn #4 against 'sd_restrictif' > libbpf: prog 'sd_restrictif_e': found map 0 (sd_restrictif, sec 7, off > 0) for insn #4 > libbpf: sec '.relcgroup_skb/egress': relo #1: insn #7 against 'is_allow_list' > libbpf: prog 'sd_restrictif_e': found data map 1 (restrict.rodata, sec > 5, off 0) for insn 7 > libbpf: sec '.relcgroup_skb/ingress': collecting relocation for > section(4) 'cgroup_skb/ingress' > libbpf: sec '.relcgroup_skb/ingress': relo #0: insn #4 against 'sd_restrictif' > libbpf: prog 'sd_restrictif_i': found map 0 (sd_restrictif, sec 7, off > 0) for insn #4 > libbpf: sec '.relcgroup_skb/ingress': relo #1: insn #7 against 'is_allow_list' > libbpf: prog 'sd_restrictif_i': found data map 1 (restrict.rodata, sec > 5, off 0) for insn 7 > >> > >> > >> >> > >> Looking at libbpf.c, it seems to me that this may be due of trying to >> > >> mmap 0 bytes in `bpf_object__init_internal_map': >> > >> >> > >> map->mmaped = mmap(NULL, bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE, >> > >> MAP_SHARED | MAP_ANONYMOUS, -1, 0); >> > >> if (map->mmaped == MAP_FAILED) { >> > >> err = -errno; >> > >> map->mmaped = NULL; >> > >> pr_warn("failed to alloc map '%s' content buffer: %d\n", >> > >> map->name, err); >> > >> zfree(&map->real_name); >> > >> zfree(&map->name); >> > >> return err; >> > >> } >> > >> >> > >> I see no check for zero sized sections in >> > >> bpf_object__init_global_data_maps. >> > >> >> > >> Is maybe GCC failing to allocate stuff in BSS that is supposed to be >> > >> there? >> > >> >> > >> > Stripped file passed to gen skeleton: >> > >> > /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool >> > >> > btf dump file >> > >> > output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o >> > >> > format raw >> > >> > [1] INT 'signed char' size=1 bits_offset=0 nr_bits=8 encoding=UNKN >> > >> > [2] INT 'unsigned char' size=1 bits_offset=0 nr_bits=8 encoding=CHAR >> > >> > [3] TYPEDEF '__u8' type_id=2 >> > >> > [4] CONST '(anon)' type_id=3 >> > >> > [5] VOLATILE '(anon)' type_id=4 >> > >> > [6] INT 'short int' size=2 bits_offset=0 nr_bits=16 encoding=SIGNED >> > >> > [7] INT 'short unsigned int' size=2 bits_offset=0 nr_bits=16 encoding=(none) >> > >> > [8] TYPEDEF '__u16' type_id=7 >> > >> > [9] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED >> > >> > [10] TYPEDEF '__s32' type_id=9 >> > >> > [11] INT 'unsigned int' size=4 bits_offset=0 nr_bits=32 encoding=(none) >> > >> > [12] TYPEDEF '__u32' type_id=11 >> > >> > [13] INT 'long long int' size=8 bits_offset=0 nr_bits=64 encoding=SIGNED >> > >> > [14] INT 'long long unsigned int' size=8 bits_offset=0 nr_bits=64 >> > >> > encoding=(none) >> > >> > [15] TYPEDEF '__u64' type_id=14 >> > >> > [16] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none) >> > >> > [17] INT 'long int' size=8 bits_offset=0 nr_bits=64 encoding=SIGNED >> > >> > [18] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=UNKN >> > >> > [19] CONST '(anon)' type_id=18 >> > >> > [20] TYPEDEF '__be16' type_id=8 >> > >> > [21] TYPEDEF '__be32' type_id=12 >> > >> > [22] ENUM 'bpf_map_type' encoding=UNSIGNED size=4 vlen=31 >> > >> > 'BPF_MAP_TYPE_UNSPEC' val=0 >> > >> > 'BPF_MAP_TYPE_HASH' val=1 >> > >> > 'BPF_MAP_TYPE_ARRAY' val=2 >> > >> > 'BPF_MAP_TYPE_PROG_ARRAY' val=3 >> > >> > 'BPF_MAP_TYPE_PERF_EVENT_ARRAY' val=4 >> > >> > 'BPF_MAP_TYPE_PERCPU_HASH' val=5 >> > >> > 'BPF_MAP_TYPE_PERCPU_ARRAY' val=6 >> > >> > 'BPF_MAP_TYPE_STACK_TRACE' val=7 >> > >> > 'BPF_MAP_TYPE_CGROUP_ARRAY' val=8 >> > >> > 'BPF_MAP_TYPE_LRU_HASH' val=9 >> > >> > 'BPF_MAP_TYPE_LRU_PERCPU_HASH' val=10 >> > >> > 'BPF_MAP_TYPE_LPM_TRIE' val=11 >> > >> > 'BPF_MAP_TYPE_ARRAY_OF_MAPS' val=12 >> > >> > 'BPF_MAP_TYPE_HASH_OF_MAPS' val=13 >> > >> > 'BPF_MAP_TYPE_DEVMAP' val=14 >> > >> > 'BPF_MAP_TYPE_SOCKMAP' val=15 >> > >> > 'BPF_MAP_TYPE_CPUMAP' val=16 >> > >> > 'BPF_MAP_TYPE_XSKMAP' val=17 >> > >> > 'BPF_MAP_TYPE_SOCKHASH' val=18 >> > >> > 'BPF_MAP_TYPE_CGROUP_STORAGE' val=19 >> > >> > 'BPF_MAP_TYPE_REUSEPORT_SOCKARRAY' val=20 >> > >> > 'BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE' val=21 >> > >> > 'BPF_MAP_TYPE_QUEUE' val=22 >> > >> > 'BPF_MAP_TYPE_STACK' val=23 >> > >> > 'BPF_MAP_TYPE_SK_STORAGE' val=24 >> > >> > 'BPF_MAP_TYPE_DEVMAP_HASH' val=25 >> > >> > 'BPF_MAP_TYPE_STRUCT_OPS' val=26 >> > >> > 'BPF_MAP_TYPE_RINGBUF' val=27 >> > >> > 'BPF_MAP_TYPE_INODE_STORAGE' val=28 >> > >> > 'BPF_MAP_TYPE_TASK_STORAGE' val=29 >> > >> > 'BPF_MAP_TYPE_BLOOM_FILTER' val=30 >> > >> > [23] UNION '(anon)' size=8 vlen=1 >> > >> > 'flow_keys' type_id=29 bits_offset=0 >> > >> > [24] STRUCT 'bpf_flow_keys' size=56 vlen=13 >> > >> > 'nhoff' type_id=8 bits_offset=0 >> > >> > 'thoff' type_id=8 bits_offset=16 >> > >> > 'addr_proto' type_id=8 bits_offset=32 >> > >> > 'is_frag' type_id=3 bits_offset=48 >> > >> > 'is_first_frag' type_id=3 bits_offset=56 >> > >> > 'is_encap' type_id=3 bits_offset=64 >> > >> > 'ip_proto' type_id=3 bits_offset=72 >> > >> > 'n_proto' type_id=20 bits_offset=80 >> > >> > 'sport' type_id=20 bits_offset=96 >> > >> > 'dport' type_id=20 bits_offset=112 >> > >> > '(anon)' type_id=25 bits_offset=128 >> > >> > 'flags' type_id=12 bits_offset=384 >> > >> > 'flow_label' type_id=21 bits_offset=416 >> > >> > [25] UNION '(anon)' size=32 vlen=2 >> > >> > '(anon)' type_id=26 bits_offset=0 >> > >> > '(anon)' type_id=27 bits_offset=0 >> > >> > [26] STRUCT '(anon)' size=8 vlen=2 >> > >> > 'ipv4_src' type_id=21 bits_offset=0 >> > >> > 'ipv4_dst' type_id=21 bits_offset=32 >> > >> > [27] STRUCT '(anon)' size=32 vlen=2 >> > >> > 'ipv6_src' type_id=28 bits_offset=0 >> > >> > 'ipv6_dst' type_id=28 bits_offset=128 >> > >> > [28] ARRAY '(anon)' type_id=12 index_type_id=16 nr_elems=4 >> > >> > [29] PTR '(anon)' type_id=24 >> > >> > [30] UNION '(anon)' size=8 vlen=1 >> > >> > 'sk' type_id=32 bits_offset=0 >> > >> > [31] STRUCT 'bpf_sock' size=80 vlen=14 >> > >> > 'bound_dev_if' type_id=12 bits_offset=0 >> > >> > 'family' type_id=12 bits_offset=32 >> > >> > 'type' type_id=12 bits_offset=64 >> > >> > 'protocol' type_id=12 bits_offset=96 >> > >> > 'mark' type_id=12 bits_offset=128 >> > >> > 'priority' type_id=12 bits_offset=160 >> > >> > 'src_ip4' type_id=12 bits_offset=192 >> > >> > 'src_ip6' type_id=28 bits_offset=224 >> > >> > 'src_port' type_id=12 bits_offset=352 >> > >> > 'dst_port' type_id=20 bits_offset=384 >> > >> > 'dst_ip4' type_id=12 bits_offset=416 >> > >> > 'dst_ip6' type_id=28 bits_offset=448 >> > >> > 'state' type_id=12 bits_offset=576 >> > >> > 'rx_queue_mapping' type_id=10 bits_offset=608 >> > >> > [32] PTR '(anon)' type_id=31 >> > >> > [33] STRUCT '__sk_buff' size=192 vlen=33 >> > >> > 'len' type_id=12 bits_offset=0 >> > >> > 'pkt_type' type_id=12 bits_offset=32 >> > >> > 'mark' type_id=12 bits_offset=64 >> > >> > 'queue_mapping' type_id=12 bits_offset=96 >> > >> > 'protocol' type_id=12 bits_offset=128 >> > >> > 'vlan_present' type_id=12 bits_offset=160 >> > >> > 'vlan_tci' type_id=12 bits_offset=192 >> > >> > 'vlan_proto' type_id=12 bits_offset=224 >> > >> > 'priority' type_id=12 bits_offset=256 >> > >> > 'ingress_ifindex' type_id=12 bits_offset=288 >> > >> > 'ifindex' type_id=12 bits_offset=320 >> > >> > 'tc_index' type_id=12 bits_offset=352 >> > >> > 'cb' type_id=34 bits_offset=384 >> > >> > 'hash' type_id=12 bits_offset=544 >> > >> > 'tc_classid' type_id=12 bits_offset=576 >> > >> > 'data' type_id=12 bits_offset=608 >> > >> > 'data_end' type_id=12 bits_offset=640 >> > >> > 'napi_id' type_id=12 bits_offset=672 >> > >> > 'family' type_id=12 bits_offset=704 >> > >> > 'remote_ip4' type_id=12 bits_offset=736 >> > >> > 'local_ip4' type_id=12 bits_offset=768 >> > >> > 'remote_ip6' type_id=28 bits_offset=800 >> > >> > 'local_ip6' type_id=28 bits_offset=928 >> > >> > 'remote_port' type_id=12 bits_offset=1056 >> > >> > 'local_port' type_id=12 bits_offset=1088 >> > >> > 'data_meta' type_id=12 bits_offset=1120 >> > >> > '(anon)' type_id=23 bits_offset=1152 >> > >> > 'tstamp' type_id=15 bits_offset=1216 >> > >> > 'wire_len' type_id=12 bits_offset=1280 >> > >> > 'gso_segs' type_id=12 bits_offset=1312 >> > >> > '(anon)' type_id=30 bits_offset=1344 >> > >> > 'gso_size' type_id=12 bits_offset=1408 >> > >> > 'hwtstamp' type_id=15 bits_offset=1472 >> > >> > [34] ARRAY '(anon)' type_id=12 index_type_id=16 nr_elems=5 >> > >> > [35] CONST '(anon)' type_id=33 >> > >> > [36] PTR '(anon)' type_id=0 >> > >> > [37] STRUCT '(anon)' size=24 vlen=3 >> > >> > 'type' type_id=39 bits_offset=0 >> > >> > 'key' type_id=40 bits_offset=64 >> > >> > 'value' type_id=41 bits_offset=128 >> > >> > [38] ARRAY '(anon)' type_id=9 index_type_id=16 nr_elems=1 >> > >> > [39] PTR '(anon)' type_id=38 >> > >> > [40] PTR '(anon)' type_id=12 >> > >> > [41] PTR '(anon)' type_id=3 >> > >> > [42] ARRAY '(anon)' type_id=19 index_type_id=16 nr_elems=18 >> > >> > [43] CONST '(anon)' type_id=42 >> > >> > [44] FUNC_PROTO '(anon)' ret_type_id=36 vlen=2 >> > >> > '(anon)' type_id=36 >> > >> > '(anon)' type_id=46 >> > >> > [45] CONST '(anon)' type_id=0 >> > >> > [46] PTR '(anon)' type_id=45 >> > >> > [47] FUNC_PROTO '(anon)' ret_type_id=9 vlen=1 >> > >> > 'sk' type_id=48 >> > >> > [48] PTR '(anon)' type_id=35 >> > >> > [49] VAR '_license' type_id=43, linkage=static >> > >> > [50] VAR 'is_allow_list' type_id=5, linkage=global >> > >> > [51] VAR 'sd_restrictif' type_id=37, linkage=global >> > >> > [52] FUNC 'sd_restrictif_i' type_id=47 linkage=global >> > >> > [53] FUNC 'sd_restrictif_e' type_id=47 linkage=global >> > >> > [54] FUNC 'restrict_network_interfaces_impl' type_id=47 linkage=static >> > >> > [55] DATASEC '.data' size=1 vlen=1 >> > >> > type_id=50 offset=0 size=1 (VAR 'is_allow_list') >> > >> > [56] DATASEC 'license' size=18 vlen=1 >> > >> > type_id=49 offset=0 size=18 (VAR '_license') >> > >> > [57] DATASEC '.maps' size=24 vlen=1 >> > >> > type_id=51 offset=0 size=24 (VAR 'sd_restrictif') >> > >> > >> > >> > File before being stripped using bpftool gen object: >> > >> > /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool >> > >> > btf dump file >> > >> > > output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o >> > >> > format raw >> > >> > [1] INT 'signed char' size=1 bits_offset=0 nr_bits=8 encoding=UNKN >> > >> > [2] INT 'unsigned char' size=1 bits_offset=0 nr_bits=8 encoding=CHAR >> > >> > [3] TYPEDEF '__u8' type_id=2 >> > >> > [4] CONST '(anon)' type_id=3 >> > >> > [5] VOLATILE '(anon)' type_id=4 >> > >> > [6] INT 'short int' size=2 bits_offset=0 nr_bits=16 encoding=SIGNED >> > >> > [7] INT 'short unsigned int' size=2 bits_offset=0 nr_bits=16 encoding=(none) >> > >> > [8] TYPEDEF '__u16' type_id=7 >> > >> > [9] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED >> > >> > [10] TYPEDEF '__s32' type_id=9 >> > >> > [11] INT 'unsigned int' size=4 bits_offset=0 nr_bits=32 encoding=(none) >> > >> > [12] TYPEDEF '__u32' type_id=11 >> > >> > [13] INT 'long long int' size=8 bits_offset=0 nr_bits=64 encoding=SIGNED >> > >> > [14] INT 'long long unsigned int' size=8 bits_offset=0 nr_bits=64 >> > >> > encoding=(none) >> > >> > [15] TYPEDEF '__u64' type_id=14 >> > >> > [16] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none) >> > >> > [17] INT 'long int' size=8 bits_offset=0 nr_bits=64 encoding=SIGNED >> > >> > [18] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=UNKN >> > >> > [19] CONST '(anon)' type_id=18 >> > >> > [20] TYPEDEF '__be16' type_id=8 >> > >> > [21] TYPEDEF '__be32' type_id=12 >> > >> > [22] ENUM 'bpf_map_type' encoding=UNSIGNED size=4 vlen=31 >> > >> > 'BPF_MAP_TYPE_UNSPEC' val=0 >> > >> > 'BPF_MAP_TYPE_HASH' val=1 >> > >> > 'BPF_MAP_TYPE_ARRAY' val=2 >> > >> > 'BPF_MAP_TYPE_PROG_ARRAY' val=3 >> > >> > 'BPF_MAP_TYPE_PERF_EVENT_ARRAY' val=4 >> > >> > 'BPF_MAP_TYPE_PERCPU_HASH' val=5 >> > >> > 'BPF_MAP_TYPE_PERCPU_ARRAY' val=6 >> > >> > 'BPF_MAP_TYPE_STACK_TRACE' val=7 >> > >> > 'BPF_MAP_TYPE_CGROUP_ARRAY' val=8 >> > >> > 'BPF_MAP_TYPE_LRU_HASH' val=9 >> > >> > 'BPF_MAP_TYPE_LRU_PERCPU_HASH' val=10 >> > >> > 'BPF_MAP_TYPE_LPM_TRIE' val=11 >> > >> > 'BPF_MAP_TYPE_ARRAY_OF_MAPS' val=12 >> > >> > 'BPF_MAP_TYPE_HASH_OF_MAPS' val=13 >> > >> > 'BPF_MAP_TYPE_DEVMAP' val=14 >> > >> > 'BPF_MAP_TYPE_SOCKMAP' val=15 >> > >> > 'BPF_MAP_TYPE_CPUMAP' val=16 >> > >> > 'BPF_MAP_TYPE_XSKMAP' val=17 >> > >> > 'BPF_MAP_TYPE_SOCKHASH' val=18 >> > >> > 'BPF_MAP_TYPE_CGROUP_STORAGE' val=19 >> > >> > 'BPF_MAP_TYPE_REUSEPORT_SOCKARRAY' val=20 >> > >> > 'BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE' val=21 >> > >> > 'BPF_MAP_TYPE_QUEUE' val=22 >> > >> > 'BPF_MAP_TYPE_STACK' val=23 >> > >> > 'BPF_MAP_TYPE_SK_STORAGE' val=24 >> > >> > 'BPF_MAP_TYPE_DEVMAP_HASH' val=25 >> > >> > 'BPF_MAP_TYPE_STRUCT_OPS' val=26 >> > >> > 'BPF_MAP_TYPE_RINGBUF' val=27 >> > >> > 'BPF_MAP_TYPE_INODE_STORAGE' val=28 >> > >> > 'BPF_MAP_TYPE_TASK_STORAGE' val=29 >> > >> > 'BPF_MAP_TYPE_BLOOM_FILTER' val=30 >> > >> > [23] UNION '(anon)' size=8 vlen=1 >> > >> > 'flow_keys' type_id=29 bits_offset=0 >> > >> > [24] STRUCT 'bpf_flow_keys' size=56 vlen=13 >> > >> > 'nhoff' type_id=8 bits_offset=0 >> > >> > 'thoff' type_id=8 bits_offset=16 >> > >> > 'addr_proto' type_id=8 bits_offset=32 >> > >> > 'is_frag' type_id=3 bits_offset=48 >> > >> > 'is_first_frag' type_id=3 bits_offset=56 >> > >> > 'is_encap' type_id=3 bits_offset=64 >> > >> > 'ip_proto' type_id=3 bits_offset=72 >> > >> > 'n_proto' type_id=20 bits_offset=80 >> > >> > 'sport' type_id=20 bits_offset=96 >> > >> > 'dport' type_id=20 bits_offset=112 >> > >> > '(anon)' type_id=25 bits_offset=128 >> > >> > 'flags' type_id=12 bits_offset=384 >> > >> > 'flow_label' type_id=21 bits_offset=416 >> > >> > [25] UNION '(anon)' size=32 vlen=2 >> > >> > '(anon)' type_id=26 bits_offset=0 >> > >> > '(anon)' type_id=27 bits_offset=0 >> > >> > [26] STRUCT '(anon)' size=8 vlen=2 >> > >> > 'ipv4_src' type_id=21 bits_offset=0 >> > >> > 'ipv4_dst' type_id=21 bits_offset=32 >> > >> > [27] STRUCT '(anon)' size=32 vlen=2 >> > >> > 'ipv6_src' type_id=28 bits_offset=0 >> > >> > 'ipv6_dst' type_id=28 bits_offset=128 >> > >> > [28] ARRAY '(anon)' type_id=12 index_type_id=16 nr_elems=4 >> > >> > [29] PTR '(anon)' type_id=24 >> > >> > [30] UNION '(anon)' size=8 vlen=1 >> > >> > 'sk' type_id=32 bits_offset=0 >> > >> > [31] STRUCT 'bpf_sock' size=80 vlen=14 >> > >> > 'bound_dev_if' type_id=12 bits_offset=0 >> > >> > 'family' type_id=12 bits_offset=32 >> > >> > 'type' type_id=12 bits_offset=64 >> > >> > 'protocol' type_id=12 bits_offset=96 >> > >> > 'mark' type_id=12 bits_offset=128 >> > >> > 'priority' type_id=12 bits_offset=160 >> > >> > 'src_ip4' type_id=12 bits_offset=192 >> > >> > 'src_ip6' type_id=28 bits_offset=224 >> > >> > 'src_port' type_id=12 bits_offset=352 >> > >> > 'dst_port' type_id=20 bits_offset=384 >> > >> > 'dst_ip4' type_id=12 bits_offset=416 >> > >> > 'dst_ip6' type_id=28 bits_offset=448 >> > >> > 'state' type_id=12 bits_offset=576 >> > >> > 'rx_queue_mapping' type_id=10 bits_offset=608 >> > >> > [32] PTR '(anon)' type_id=31 >> > >> > [33] STRUCT '__sk_buff' size=192 vlen=33 >> > >> > 'len' type_id=12 bits_offset=0 >> > >> > 'pkt_type' type_id=12 bits_offset=32 >> > >> > 'mark' type_id=12 bits_offset=64 >> > >> > 'queue_mapping' type_id=12 bits_offset=96 >> > >> > 'protocol' type_id=12 bits_offset=128 >> > >> > 'vlan_present' type_id=12 bits_offset=160 >> > >> > 'vlan_tci' type_id=12 bits_offset=192 >> > >> > 'vlan_proto' type_id=12 bits_offset=224 >> > >> > 'priority' type_id=12 bits_offset=256 >> > >> > 'ingress_ifindex' type_id=12 bits_offset=288 >> > >> > 'ifindex' type_id=12 bits_offset=320 >> > >> > 'tc_index' type_id=12 bits_offset=352 >> > >> > 'cb' type_id=34 bits_offset=384 >> > >> > 'hash' type_id=12 bits_offset=544 >> > >> > 'tc_classid' type_id=12 bits_offset=576 >> > >> > 'data' type_id=12 bits_offset=608 >> > >> > 'data_end' type_id=12 bits_offset=640 >> > >> > 'napi_id' type_id=12 bits_offset=672 >> > >> > 'family' type_id=12 bits_offset=704 >> > >> > 'remote_ip4' type_id=12 bits_offset=736 >> > >> > 'local_ip4' type_id=12 bits_offset=768 >> > >> > 'remote_ip6' type_id=28 bits_offset=800 >> > >> > 'local_ip6' type_id=28 bits_offset=928 >> > >> > 'remote_port' type_id=12 bits_offset=1056 >> > >> > 'local_port' type_id=12 bits_offset=1088 >> > >> > 'data_meta' type_id=12 bits_offset=1120 >> > >> > '(anon)' type_id=23 bits_offset=1152 >> > >> > 'tstamp' type_id=15 bits_offset=1216 >> > >> > 'wire_len' type_id=12 bits_offset=1280 >> > >> > 'gso_segs' type_id=12 bits_offset=1312 >> > >> > '(anon)' type_id=30 bits_offset=1344 >> > >> > 'gso_size' type_id=12 bits_offset=1408 >> > >> > 'hwtstamp' type_id=15 bits_offset=1472 >> > >> > [34] ARRAY '(anon)' type_id=12 index_type_id=16 nr_elems=5 >> > >> > [35] CONST '(anon)' type_id=33 >> > >> > [36] PTR '(anon)' type_id=0 >> > >> > [37] STRUCT '(anon)' size=24 vlen=3 >> > >> > 'type' type_id=39 bits_offset=0 >> > >> > 'key' type_id=40 bits_offset=64 >> > >> > 'value' type_id=41 bits_offset=128 >> > >> > [38] ARRAY '(anon)' type_id=9 index_type_id=16 nr_elems=1 >> > >> > [39] PTR '(anon)' type_id=38 >> > >> > [40] PTR '(anon)' type_id=12 >> > >> > [41] PTR '(anon)' type_id=3 >> > >> > [42] ARRAY '(anon)' type_id=19 index_type_id=16 nr_elems=18 >> > >> > [43] CONST '(anon)' type_id=42 >> > >> > [44] FUNC_PROTO '(anon)' ret_type_id=36 vlen=2 >> > >> > '(anon)' type_id=36 >> > >> > '(anon)' type_id=46 >> > >> > [45] CONST '(anon)' type_id=0 >> > >> > [46] PTR '(anon)' type_id=45 >> > >> > [47] FUNC_PROTO '(anon)' ret_type_id=9 vlen=1 >> > >> > 'sk' type_id=48 >> > >> > [48] PTR '(anon)' type_id=35 >> > >> > [49] FUNC_PROTO '(anon)' ret_type_id=9 vlen=1 >> > >> > 'sk' type_id=48 >> > >> > [50] FUNC_PROTO '(anon)' ret_type_id=9 vlen=1 >> > >> > 'sk' type_id=48 >> > >> > [51] VAR '_license' type_id=43, linkage=static >> > >> > [52] VAR 'is_allow_list' type_id=5, linkage=global >> > >> > [53] VAR 'sd_restrictif' type_id=37, linkage=global >> > >> > [54] FUNC 'bpf_map_lookup_elem' type_id=44 linkage=global >> > >> > [55] FUNC 'sd_restrictif_i' type_id=47 linkage=global >> > >> > [56] FUNC 'sd_restrictif_e' type_id=49 linkage=global >> > >> > [57] FUNC 'restrict_network_interfaces_impl' type_id=50 linkage=static >> > >> > [58] DATASEC 'license' size=0 vlen=1 >> > >> > type_id=51 offset=0 size=18 (VAR '_license') >> > >> > [59] DATASEC '.maps' size=0 vlen=1 >> > >> > type_id=53 offset=0 size=24 (VAR 'sd_restrictif') >> > >> > [60] DATASEC '.data' size=0 vlen=1 >> > >> > type_id=52 offset=0 size=1 (VAR 'is_allow_list') >> > >> > >> > >> >> >> > >> >> >> GCC is wrong, clearly. This function is global ([0]) and libbpf >> > >> >> >> expects it to be marked as such in BTF. >> > >> >> >> >> > >> >> >> >> > >> > > https://github.com/systemd/systemd/blob/main/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.c#L42-L50 >> > >> >> >> >> > >> >> >> >> > >> >> >>> GCC: >> > >> >> >>> >> > >> >> >>> [1] INT 'signed char' size=1 bits_offset=0 nr_bits=8 encoding=UNKN >> > >> >> >>> [2] INT 'unsigned char' size=1 bits_offset=0 nr_bits=8 encoding=CHAR >> > >> >> >>> [3] TYPEDEF '__u8' type_id=2 >> > >> >> >>> [4] CONST '(anon)' type_id=3 >> > >> >> >> >> > >> >> >> [...]
