Commit c09add2f authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov

tools/libbpf: Add bpf_iter support

Two new libbpf APIs are added to support bpf_iter:
  - bpf_program__attach_iter
    Given a bpf program and additional parameters, which is
    none now, returns a bpf_link.
  - bpf_iter_create
    syscall level API to create a bpf iterator.

The macro BPF_SEQ_PRINTF are also introduced. The format
looks like:
  BPF_SEQ_PRINTF(seq, "task id %d\n", pid);

This macro can help bpf program writers with
nicer bpf_seq_printf syntax similar to the kernel one.
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175917.2476936-1-yhs@fb.com
parent 9c5f8a10
......@@ -619,6 +619,16 @@ int bpf_link_update(int link_fd, int new_prog_fd,
return sys_bpf(BPF_LINK_UPDATE, &attr, sizeof(attr));
}
int bpf_iter_create(int link_fd)
{
union bpf_attr attr;
memset(&attr, 0, sizeof(attr));
attr.iter_create.link_fd = link_fd;
return sys_bpf(BPF_ITER_CREATE, &attr, sizeof(attr));
}
int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,
__u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt)
{
......
......@@ -187,6 +187,8 @@ struct bpf_link_update_opts {
LIBBPF_API int bpf_link_update(int link_fd, int new_prog_fd,
const struct bpf_link_update_opts *opts);
LIBBPF_API int bpf_iter_create(int link_fd);
struct bpf_prog_test_run_attr {
int prog_fd;
int repeat;
......
......@@ -413,4 +413,20 @@ typeof(name(0)) name(struct pt_regs *ctx) \
} \
static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)
/*
* BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values
* in a structure.
*/
#define BPF_SEQ_PRINTF(seq, fmt, args...) \
({ \
_Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
static const char ___fmt[] = fmt; \
unsigned long long ___param[] = { args }; \
_Pragma("GCC diagnostic pop") \
int ___ret = bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \
___param, sizeof(___param)); \
___ret; \
})
#endif
......@@ -6586,6 +6586,8 @@ static struct bpf_link *attach_trace(const struct bpf_sec_def *sec,
struct bpf_program *prog);
static struct bpf_link *attach_lsm(const struct bpf_sec_def *sec,
struct bpf_program *prog);
static struct bpf_link *attach_iter(const struct bpf_sec_def *sec,
struct bpf_program *prog);
static const struct bpf_sec_def section_defs[] = {
BPF_PROG_SEC("socket", BPF_PROG_TYPE_SOCKET_FILTER),
......@@ -6629,6 +6631,10 @@ static const struct bpf_sec_def section_defs[] = {
.is_attach_btf = true,
.expected_attach_type = BPF_LSM_MAC,
.attach_fn = attach_lsm),
SEC_DEF("iter/", TRACING,
.expected_attach_type = BPF_TRACE_ITER,
.is_attach_btf = true,
.attach_fn = attach_iter),
BPF_PROG_SEC("xdp", BPF_PROG_TYPE_XDP),
BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT),
BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN),
......@@ -6891,6 +6897,7 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
#define BTF_TRACE_PREFIX "btf_trace_"
#define BTF_LSM_PREFIX "bpf_lsm_"
#define BTF_ITER_PREFIX "__bpf_iter__"
#define BTF_MAX_NAME_SIZE 128
static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
......@@ -6921,6 +6928,9 @@ static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name,
else if (attach_type == BPF_LSM_MAC)
err = find_btf_by_prefix_kind(btf, BTF_LSM_PREFIX, name,
BTF_KIND_FUNC);
else if (attach_type == BPF_TRACE_ITER)
err = find_btf_by_prefix_kind(btf, BTF_ITER_PREFIX, name,
BTF_KIND_FUNC);
else
err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
......@@ -7848,6 +7858,12 @@ static struct bpf_link *attach_lsm(const struct bpf_sec_def *sec,
return bpf_program__attach_lsm(prog);
}
static struct bpf_link *attach_iter(const struct bpf_sec_def *sec,
struct bpf_program *prog)
{
return bpf_program__attach_iter(prog, NULL);
}
struct bpf_link *
bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd)
{
......@@ -7882,6 +7898,42 @@ bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd)
return link;
}
struct bpf_link *
bpf_program__attach_iter(struct bpf_program *prog,
const struct bpf_iter_attach_opts *opts)
{
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
int prog_fd, link_fd;
if (!OPTS_VALID(opts, bpf_iter_attach_opts))
return ERR_PTR(-EINVAL);
prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) {
pr_warn("program '%s': can't attach before loaded\n",
bpf_program__title(prog, false));
return ERR_PTR(-EINVAL);
}
link = calloc(1, sizeof(*link));
if (!link)
return ERR_PTR(-ENOMEM);
link->detach = &bpf_link__detach_fd;
link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_ITER, NULL);
if (link_fd < 0) {
link_fd = -errno;
free(link);
pr_warn("program '%s': failed to attach to iterator: %s\n",
bpf_program__title(prog, false),
libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
return ERR_PTR(link_fd);
}
link->fd = link_fd;
return link;
}
struct bpf_link *bpf_program__attach(struct bpf_program *prog)
{
const struct bpf_sec_def *sec_def;
......
......@@ -258,6 +258,15 @@ struct bpf_map;
LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map);
struct bpf_iter_attach_opts {
size_t sz; /* size of this struct for forward/backward compatibility */
};
#define bpf_iter_attach_opts__last_field sz
LIBBPF_API struct bpf_link *
bpf_program__attach_iter(struct bpf_program *prog,
const struct bpf_iter_attach_opts *opts);
struct bpf_insn;
/*
......
......@@ -258,6 +258,8 @@ LIBBPF_0.0.8 {
LIBBPF_0.0.9 {
global:
bpf_enable_stats;
bpf_iter_create;
bpf_link_get_fd_by_id;
bpf_link_get_next_id;
bpf_program__attach_iter;
} LIBBPF_0.0.8;
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