Commit a5359091 authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Alexei Starovoitov

libbpf: Add support for freplace attachment in bpf_link_create

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: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/160138355387.48470.18026176785351166890.stgit@toke.dk
parent 43bc2874
......@@ -586,19 +586,31 @@ int bpf_link_create(int prog_fd, int target_fd,
enum bpf_attach_type attach_type,
const struct bpf_link_create_opts *opts)
{
__u32 target_btf_id, iter_info_len;
union bpf_attr attr;
if (!OPTS_VALID(opts, bpf_link_create_opts))
return -EINVAL;
iter_info_len = OPTS_GET(opts, iter_info_len, 0);
target_btf_id = OPTS_GET(opts, target_btf_id, 0);
if (iter_info_len && target_btf_id)
return -EINVAL;
memset(&attr, 0, sizeof(attr));
attr.link_create.prog_fd = prog_fd;
attr.link_create.target_fd = target_fd;
attr.link_create.attach_type = attach_type;
attr.link_create.flags = OPTS_GET(opts, flags, 0);
if (iter_info_len) {
attr.link_create.iter_info =
ptr_to_u64(OPTS_GET(opts, iter_info, (void *)0));
attr.link_create.iter_info_len = OPTS_GET(opts, iter_info_len, 0);
attr.link_create.iter_info_len = iter_info_len;
} else if (target_btf_id) {
attr.link_create.target_btf_id = target_btf_id;
}
return sys_bpf(BPF_LINK_CREATE, &attr, sizeof(attr));
}
......
......@@ -174,8 +174,9 @@ struct bpf_link_create_opts {
__u32 flags;
union bpf_iter_link_info *iter_info;
__u32 iter_info_len;
__u32 target_btf_id;
};
#define bpf_link_create_opts__last_field iter_info_len
#define bpf_link_create_opts__last_field target_btf_id
LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,
enum bpf_attach_type attach_type,
......
......@@ -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 *
......
......@@ -261,6 +261,9 @@ LIBBPF_API struct bpf_link *
bpf_program__attach_netns(struct bpf_program *prog, int netns_fd);
LIBBPF_API struct bpf_link *
bpf_program__attach_xdp(struct bpf_program *prog, int ifindex);
LIBBPF_API struct bpf_link *
bpf_program__attach_freplace(struct bpf_program *prog,
int target_fd, const char *attach_func_name);
struct bpf_map;
......
......@@ -304,6 +304,7 @@ LIBBPF_0.2.0 {
global:
bpf_prog_bind_map;
bpf_prog_test_run_opts;
bpf_program__attach_freplace;
bpf_program__section_name;
btf__add_array;
btf__add_const;
......
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