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libbpf: Assign cookies to links in libbpf.

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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
This commit is contained in:
Kui-Feng Lee 2022-05-10 13:59:22 -07:00 committed by Andrii Nakryiko
parent 2fcc82411e
commit 129b9c5ee2
5 changed files with 40 additions and 4 deletions
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8
tools/lib/bpf/bpf.c
View File

@ -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);

3
tools/lib/bpf/bpf.h
View File

@ -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;
};

20
tools/lib/bpf/libbpf.c
View File

@ -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)

12
tools/lib/bpf/libbpf.h
View File

@ -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 *

1
tools/lib/bpf/libbpf.map
View File

@ -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;