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libbpf: Add support for freplace attachment in bpf_link_create

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This adds support for supplying a target btf ID for the bpf_link_create()
operation, and adds a new bpf_program__attach_freplace() high-level API for
attaching freplace functions with a target.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/160138355387.48470.18026176785351166890.stgit@toke.dk
This commit is contained in:
Toke Høiland-Jørgensen
2020-09-29 14:45:53 +02:00
committed by Andrii Nakryiko
parent 5e359219aa
commit e40af4de0c
5 changed files with 60 additions and 9 deletions
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44
src/libbpf.c
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@@ -9390,9 +9390,11 @@ static struct bpf_link *attach_iter(const struct bpf_sec_def *sec,
}
static struct bpf_link *
bpf_program__attach_fd(struct bpf_program *prog, int target_fd,
bpf_program__attach_fd(struct bpf_program *prog, int target_fd, int btf_id,
const char *target_name)
{
DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,
.target_btf_id = btf_id);
enum bpf_attach_type attach_type;
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
@@ -9410,7 +9412,7 @@ bpf_program__attach_fd(struct bpf_program *prog, int target_fd,
link->detach = &bpf_link__detach_fd;
attach_type = bpf_program__get_expected_attach_type(prog);
link_fd = bpf_link_create(prog_fd, target_fd, attach_type, NULL);
link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts);
if (link_fd < 0) {
link_fd = -errno;
free(link);
@@ -9426,19 +9428,51 @@ bpf_program__attach_fd(struct bpf_program *prog, int target_fd,
struct bpf_link *
bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd)
{
return bpf_program__attach_fd(prog, cgroup_fd, "cgroup");
return bpf_program__attach_fd(prog, cgroup_fd, 0, "cgroup");
}
struct bpf_link *
bpf_program__attach_netns(struct bpf_program *prog, int netns_fd)
{
return bpf_program__attach_fd(prog, netns_fd, "netns");
return bpf_program__attach_fd(prog, netns_fd, 0, "netns");
}
struct bpf_link *bpf_program__attach_xdp(struct bpf_program *prog, int ifindex)
{
/* target_fd/target_ifindex use the same field in LINK_CREATE */
return bpf_program__attach_fd(prog, ifindex, "xdp");
return bpf_program__attach_fd(prog, ifindex, 0, "xdp");
}
struct bpf_link *bpf_program__attach_freplace(struct bpf_program *prog,
int target_fd,
const char *attach_func_name)
{
int btf_id;
if (!!target_fd != !!attach_func_name) {
pr_warn("prog '%s': supply none or both of target_fd and attach_func_name\n",
prog->name);
return ERR_PTR(-EINVAL);
}
if (prog->type != BPF_PROG_TYPE_EXT) {
pr_warn("prog '%s': only BPF_PROG_TYPE_EXT can attach as freplace",
prog->name);
return ERR_PTR(-EINVAL);
}
if (target_fd) {
btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);
if (btf_id < 0)
return ERR_PTR(btf_id);
return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace");
} else {
/* no target, so use raw_tracepoint_open for compatibility
* with old kernels
*/
return bpf_program__attach_trace(prog);
}
}
struct bpf_link *