From 0e6d0a9d2348b64df74239e859fa9d6e86cdcdef Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 25 Jan 2024 12:55:04 -0800 Subject: libbpf: integrate __arg_ctx feature detector into kernel_supports() Now that feature detection code is in bpf-next tree, integrate __arg_ctx kernel-side support into kernel_supports() framework. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240125205510.3642094-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/libbpf.c | 65 +------------------------------------------------- 1 file changed, 1 insertion(+), 64 deletions(-) (limited to 'tools/lib/bpf/libbpf.c') diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index fa7094ff3e66..41ab7a21f868 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -6462,69 +6462,6 @@ static int clone_func_btf_info(struct btf *btf, int orig_fn_id, struct bpf_progr return fn_id; } -static int probe_kern_arg_ctx_tag(void) -{ - /* To minimize merge conflicts with BPF token series that refactors - * feature detection code a lot, we don't integrate - * probe_kern_arg_ctx_tag() into kernel_supports() feature-detection - * framework yet, doing our own caching internally. - * This will be cleaned up a bit later when bpf/bpf-next trees settle. - */ - static int cached_result = -1; - 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); - int prog_fd, btf_fd, insn_cnt = ARRAY_SIZE(insns); - - if (cached_result >= 0) - return cached_result; - - btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs), 0); - 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); - - cached_result = probe_fd(prog_fd); - return cached_result; -} - /* Check if main program or global subprog's function prototype has `arg:ctx` * argument tags, and, if necessary, substitute correct type to match what BPF * verifier would expect, taking into account specific program type. This @@ -6549,7 +6486,7 @@ static int bpf_program_fixup_func_info(struct bpf_object *obj, struct bpf_progra return 0; /* don't do any fix ups if kernel natively supports __arg_ctx */ - if (probe_kern_arg_ctx_tag() > 0) + if (kernel_supports(obj, FEAT_ARG_CTX_TAG)) return 0; /* some BPF program types just don't have named context structs, so -- cgit