diff options
Diffstat (limited to 'tools/lib/bpf/features.c')
| -rw-r--r-- | tools/lib/bpf/features.c | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/tools/lib/bpf/features.c b/tools/lib/bpf/features.c index 5a5c766bf615..6b0738ad7063 100644 --- a/tools/lib/bpf/features.c +++ b/tools/lib/bpf/features.c @@ -407,6 +407,61 @@ static int probe_kern_btf_enum64(int token_fd) strs, sizeof(strs), token_fd)); } +static int probe_kern_arg_ctx_tag(int token_fd) +{ + static const char strs[] = "\0a\0b\0arg:ctx\0"; + const __u32 types[] = { + /* [1] INT */ + BTF_TYPE_INT_ENC(1 /* "a" */, BTF_INT_SIGNED, 0, 32, 4), + /* [2] PTR -> VOID */ + BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 0), + /* [3] FUNC_PROTO `int(void *a)` */ + BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 1), + BTF_PARAM_ENC(1 /* "a" */, 2), + /* [4] FUNC 'a' -> FUNC_PROTO (main prog) */ + BTF_TYPE_ENC(1 /* "a" */, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 3), + /* [5] FUNC_PROTO `int(void *b __arg_ctx)` */ + BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 1), + BTF_PARAM_ENC(3 /* "b" */, 2), + /* [6] FUNC 'b' -> FUNC_PROTO (subprog) */ + BTF_TYPE_ENC(3 /* "b" */, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 5), + /* [7] DECL_TAG 'arg:ctx' -> func 'b' arg 'b' */ + BTF_TYPE_DECL_TAG_ENC(5 /* "arg:ctx" */, 6, 0), + }; + const struct bpf_insn insns[] = { + /* main prog */ + BPF_CALL_REL(+1), + BPF_EXIT_INSN(), + /* global subprog */ + BPF_EMIT_CALL(BPF_FUNC_get_func_ip), /* needs PTR_TO_CTX */ + BPF_EXIT_INSN(), + }; + const struct bpf_func_info_min func_infos[] = { + { 0, 4 }, /* main prog -> FUNC 'a' */ + { 2, 6 }, /* subprog -> FUNC 'b' */ + }; + LIBBPF_OPTS(bpf_prog_load_opts, opts, + .token_fd = token_fd, + .prog_flags = token_fd ? BPF_F_TOKEN_FD : 0, + ); + int prog_fd, btf_fd, insn_cnt = ARRAY_SIZE(insns); + + btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs), token_fd); + if (btf_fd < 0) + return 0; + + opts.prog_btf_fd = btf_fd; + opts.func_info = &func_infos; + opts.func_info_cnt = ARRAY_SIZE(func_infos); + opts.func_info_rec_size = sizeof(func_infos[0]); + + prog_fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, "det_arg_ctx", + "GPL", insns, insn_cnt, &opts); + close(btf_fd); + + return probe_fd(prog_fd); +} + typedef int (*feature_probe_fn)(int /* token_fd */); static struct kern_feature_cache feature_cache; @@ -476,6 +531,9 @@ static struct kern_feature_desc { [FEAT_UPROBE_MULTI_LINK] = { "BPF multi-uprobe link support", probe_uprobe_multi_link, }, + [FEAT_ARG_CTX_TAG] = { + "kernel-side __arg_ctx tag", probe_kern_arg_ctx_tag, + }, }; bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id) |