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tools/libbpf: Add support for bpf map element iterator

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Add map_fd to bpf_iter_attach_opts and flags to
bpf_link_create_opts. Later on, bpftool or selftest
will be able to create a bpf map element iterator
by passing map_fd to the kernel during link
creation time.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200723184117.590673-1-yhs@fb.com
This commit is contained in:
Yonghong Song
2020-07-23 11:41:17 -07:00
committed by Andrii Nakryiko
parent b1720407ff
commit 5efd8395ef
4 changed files with 14 additions and 3 deletions
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1
src/bpf.c
View File

@@ -598,6 +598,7 @@ int bpf_link_create(int prog_fd, int target_fd,
attr.link_create.prog_fd = prog_fd; attr.link_create.prog_fd = prog_fd;
attr.link_create.target_fd = target_fd; attr.link_create.target_fd = target_fd;
attr.link_create.attach_type = attach_type; attr.link_create.attach_type = attach_type;
attr.link_create.flags = OPTS_GET(opts, flags, 0);
return sys_bpf(BPF_LINK_CREATE, &attr, sizeof(attr)); return sys_bpf(BPF_LINK_CREATE, &attr, sizeof(attr));
} }

3
src/bpf.h
View File

@@ -170,8 +170,9 @@ LIBBPF_API int bpf_prog_detach2(int prog_fd, int attachable_fd,
struct bpf_link_create_opts { struct bpf_link_create_opts {
size_t sz; /* size of this struct for forward/backward compatibility */ size_t sz; /* size of this struct for forward/backward compatibility */
__u32 flags;
}; };
#define bpf_link_create_opts__last_field sz #define bpf_link_create_opts__last_field flags
LIBBPF_API int bpf_link_create(int prog_fd, int target_fd, LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,
enum bpf_attach_type attach_type, enum bpf_attach_type attach_type,

10
src/libbpf.c
View File

@@ -8282,13 +8282,20 @@ struct bpf_link *
bpf_program__attach_iter(struct bpf_program *prog, bpf_program__attach_iter(struct bpf_program *prog,
const struct bpf_iter_attach_opts *opts) const struct bpf_iter_attach_opts *opts)
{ {
DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
char errmsg[STRERR_BUFSIZE]; char errmsg[STRERR_BUFSIZE];
struct bpf_link *link; struct bpf_link *link;
int prog_fd, link_fd; int prog_fd, link_fd;
__u32 target_fd = 0;
if (!OPTS_VALID(opts, bpf_iter_attach_opts)) if (!OPTS_VALID(opts, bpf_iter_attach_opts))
return ERR_PTR(-EINVAL); return ERR_PTR(-EINVAL);
if (OPTS_HAS(opts, map_fd)) {
target_fd = opts->map_fd;
link_create_opts.flags = BPF_ITER_LINK_MAP_FD;
}
prog_fd = bpf_program__fd(prog); prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) { if (prog_fd < 0) {
pr_warn("program '%s': can't attach before loaded\n", pr_warn("program '%s': can't attach before loaded\n",
@@ -8301,7 +8308,8 @@ bpf_program__attach_iter(struct bpf_program *prog,
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
link->detach = &bpf_link__detach_fd; link->detach = &bpf_link__detach_fd;
link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_ITER, NULL); link_fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_ITER,
&link_create_opts);
if (link_fd < 0) { if (link_fd < 0) {
link_fd = -errno; link_fd = -errno;
free(link); free(link);

3
src/libbpf.h
View File

@@ -264,8 +264,9 @@ LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map);
struct bpf_iter_attach_opts { struct bpf_iter_attach_opts {
size_t sz; /* size of this struct for forward/backward compatibility */ size_t sz; /* size of this struct for forward/backward compatibility */
__u32 map_fd;
}; };
#define bpf_iter_attach_opts__last_field sz #define bpf_iter_attach_opts__last_field map_fd
LIBBPF_API struct bpf_link * LIBBPF_API struct bpf_link *
bpf_program__attach_iter(struct bpf_program *prog, bpf_program__attach_iter(struct bpf_program *prog,