libbpf: Assign cookies to links in libbpf.

Add a cookie field to the attributes of bpf_link_create().
Add bpf_program__attach_trace_opts() to attach a cookie to a link.

Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220510205923.3206889-5-kuifeng@fb.com

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index a9d292c106c29e5581657b3c3cca3c312b07eccf..5660268e103f05d0979dfeb75e385ecbcd10ee89 100644 (file)
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -863,6 +863,14 @@ int bpf_link_create(int prog_fd, int target_fd,
                if (!OPTS_ZEROED(opts, kprobe_multi))
                        return libbpf_err(-EINVAL);
                break;
+       case BPF_TRACE_FENTRY:
+       case BPF_TRACE_FEXIT:
+       case BPF_MODIFY_RETURN:
+       case BPF_LSM_MAC:
+               attr.link_create.tracing.cookie = OPTS_GET(opts, tracing.cookie, 0);
+               if (!OPTS_ZEROED(opts, tracing))
+                       return libbpf_err(-EINVAL);
+               break;
        default:
                if (!OPTS_ZEROED(opts, flags))
                        return libbpf_err(-EINVAL);

diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index f4b4afb6d4ba754be0cc01a49c58410ff7c977fa..34af2232928c865ce894a68ce35656defc6fb4bb 100644 (file)
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -420,6 +420,9 @@ struct bpf_link_create_opts {
                        const unsigned long *addrs;
                        const __u64 *cookies;
                } kprobe_multi;
+               struct {
+                       __u64 cookie;
+               } tracing;
        };
        size_t :0;
 };

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 15117b9a4d1e882e63db2ac2b29c4e9ed3d4490a..a5904c0ac7940e8832fe0258e2d0ac0a41d6cecd 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11568,12 +11568,17 @@ static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf
 }
 
 /* Common logic for all BPF program types that attach to a btf_id */
-static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog)
+static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog,
+                                                  const struct bpf_trace_opts *opts)
 {
+       LIBBPF_OPTS(bpf_link_create_opts, link_opts);
        char errmsg[STRERR_BUFSIZE];
        struct bpf_link *link;
        int prog_fd, pfd;
 
+       if (!OPTS_VALID(opts, bpf_trace_opts))
+               return libbpf_err_ptr(-EINVAL);
+
        prog_fd = bpf_program__fd(prog);
        if (prog_fd < 0) {
                pr_warn("prog '%s': can't attach before loaded\n", prog->name);
@@ -11586,7 +11591,8 @@ static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *pro
        link->detach = &bpf_link__detach_fd;
 
        /* libbpf is smart enough to redirect to BPF_RAW_TRACEPOINT_OPEN on old kernels */
-       pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), NULL);
+       link_opts.tracing.cookie = OPTS_GET(opts, cookie, 0);
+       pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), &link_opts);
        if (pfd < 0) {
                pfd = -errno;
                free(link);
@@ -11600,12 +11606,18 @@ static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *pro
 
 struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
 {
-       return bpf_program__attach_btf_id(prog);
+       return bpf_program__attach_btf_id(prog, NULL);
+}
+
+struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,
+                                               const struct bpf_trace_opts *opts)
+{
+       return bpf_program__attach_btf_id(prog, opts);
 }
 
 struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)
 {
-       return bpf_program__attach_btf_id(prog);
+       return bpf_program__attach_btf_id(prog, NULL);
 }
 
 static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link)

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 114b1f6f73a57afecb418400a4723fd231cb87db..a1fb91810378818b702678d2f2a47ed8316d195f 100644 (file)
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -603,8 +603,20 @@ bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
 LIBBPF_API struct bpf_link *
 bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
                                   const char *tp_name);
+
+struct bpf_trace_opts {
+       /* size of this struct, for forward/backward compatibility */
+       size_t sz;
+       /* custom user-provided value fetchable through bpf_get_attach_cookie() */
+       __u64 cookie;
+};
+#define bpf_trace_opts__last_field cookie
+
 LIBBPF_API struct bpf_link *
 bpf_program__attach_trace(const struct bpf_program *prog);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_trace_opts(const struct bpf_program *prog, const struct bpf_trace_opts *opts);
+
 LIBBPF_API struct bpf_link *
 bpf_program__attach_lsm(const struct bpf_program *prog);
 LIBBPF_API struct bpf_link *

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index b5bc84039407abe869868d5ae553a457ecce6a6d..80819e26a976dda8852f7dcf60a8c32a96a14669 100644 (file)
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -447,6 +447,7 @@ LIBBPF_0.8.0 {
                bpf_object__destroy_subskeleton;
                bpf_object__open_subskeleton;
                bpf_program__attach_kprobe_multi_opts;
+               bpf_program__attach_trace_opts;
                bpf_program__attach_usdt;
                libbpf_register_prog_handler;
                libbpf_unregister_prog_handler;