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Date: Thu, 18 Nov 2021 12:24:48 +0100
From: Jiri Olsa <jolsa@...hat.com>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...omium.org>
Subject: [PATCH bpf-next 22/29] libbpf: Add support to link multi func tracing program
Adding support to link multi func tracing program
through link_create interface.
Adding special types for multi func programs:
fentry.multi
fexit.multi
so you can define multi func programs like:
SEC("fentry.multi/bpf_fentry_test*")
int BPF_PROG(test1, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f)
that defines test1 to be attached to bpf_fentry_test* functions.
The test1 program is loaded with BPF_F_MULTI_FUNC flag.
If functions are not specified the program needs to be attached
manually.
Adding new btf_ids/btf_ids_cnt fields to bpf_link_create_opts,
that define functions to attach the program to.
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
tools/lib/bpf/bpf.c | 7 +++++
tools/lib/bpf/bpf.h | 6 +++-
tools/lib/bpf/libbpf.c | 66 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 78 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 94560ba31724..86a95419e501 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -784,6 +784,13 @@ int bpf_link_create(int prog_fd, int target_fd,
if (!OPTS_ZEROED(opts, perf_event))
return libbpf_err(-EINVAL);
break;
+ case BPF_TRACE_FENTRY:
+ case BPF_TRACE_FEXIT:
+ attr.link_create.multi.btf_ids = (__u64) OPTS_GET(opts, multi.btf_ids, 0);
+ attr.link_create.multi.btf_ids_cnt = OPTS_GET(opts, multi.btf_ids_cnt, 0);
+ if (!OPTS_ZEROED(opts, multi))
+ return libbpf_err(-EINVAL);
+ break;
default:
if (!OPTS_ZEROED(opts, flags))
return libbpf_err(-EINVAL);
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 079cc81ac51e..e55abf3528b3 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -249,10 +249,14 @@ struct bpf_link_create_opts {
struct {
__u64 bpf_cookie;
} perf_event;
+ struct {
+ __u32 *btf_ids;
+ __u32 btf_ids_cnt;
+ } multi;
};
size_t :0;
};
-#define bpf_link_create_opts__last_field perf_event
+#define bpf_link_create_opts__last_field multi
LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,
enum bpf_attach_type attach_type,
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index de7e09a6b5ec..4c11d38b1f92 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -246,6 +246,8 @@ enum sec_def_flags {
SEC_SLEEPABLE = 8,
/* allow non-strict prefix matching */
SEC_SLOPPY_PFX = 16,
+ /* BPF program type allows multiple functions attachment */
+ SEC_MULTI_FUNC = 32,
};
struct bpf_sec_def {
@@ -6723,6 +6725,9 @@ static int bpf_object_init_progs(struct bpf_object *obj, const struct bpf_object
continue;
}
+ if (prog->sec_def->cookie & SEC_MULTI_FUNC)
+ prog->prog_flags |= BPF_F_MULTI_FUNC;
+
bpf_program__set_type(prog, prog->sec_def->prog_type);
bpf_program__set_expected_attach_type(prog, prog->sec_def->expected_attach_type);
@@ -8318,6 +8323,7 @@ static struct bpf_link *attach_kprobe(const struct bpf_program *prog, long cooki
static struct bpf_link *attach_tp(const struct bpf_program *prog, long cookie);
static struct bpf_link *attach_raw_tp(const struct bpf_program *prog, long cookie);
static struct bpf_link *attach_trace(const struct bpf_program *prog, long cookie);
+static struct bpf_link *attach_trace_multi(const struct bpf_program *prog, long cookie);
static struct bpf_link *attach_lsm(const struct bpf_program *prog, long cookie);
static struct bpf_link *attach_iter(const struct bpf_program *prog, long cookie);
@@ -8345,6 +8351,8 @@ static const struct bpf_sec_def section_defs[] = {
SEC_DEF("fentry.s/", TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
SEC_DEF("fmod_ret.s/", TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
SEC_DEF("fexit.s/", TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+ SEC_DEF("fentry.multi/", TRACING, BPF_TRACE_FENTRY, SEC_MULTI_FUNC, attach_trace_multi),
+ SEC_DEF("fexit.multi/", TRACING, BPF_TRACE_FEXIT, SEC_MULTI_FUNC, attach_trace_multi),
SEC_DEF("freplace/", EXT, 0, SEC_ATTACH_BTF, attach_trace),
SEC_DEF("lsm/", LSM, BPF_LSM_MAC, SEC_ATTACH_BTF, attach_lsm),
SEC_DEF("lsm.s/", LSM, BPF_LSM_MAC, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_lsm),
@@ -8797,6 +8805,9 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attac
__u32 attach_prog_fd = prog->attach_prog_fd;
int err = 0;
+ if (prog->prog_flags & BPF_F_MULTI_FUNC)
+ return 0;
+
/* BPF program's BTF ID */
if (attach_prog_fd) {
err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd);
@@ -10216,6 +10227,61 @@ static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *pro
return (struct bpf_link *)link;
}
+static struct bpf_link *bpf_program__attach_multi(const struct bpf_program *prog)
+{
+ char *pattern = prog->sec_name + strlen(prog->sec_def->sec);
+ DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts);
+ enum bpf_attach_type attach_type;
+ int prog_fd, link_fd, cnt, err;
+ struct bpf_link *link = NULL;
+ __u32 *ids = NULL;
+
+ prog_fd = bpf_program__fd(prog);
+ if (prog_fd < 0) {
+ pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+ return ERR_PTR(-EINVAL);
+ }
+
+ err = bpf_object__load_vmlinux_btf(prog->obj, true);
+ if (err)
+ return ERR_PTR(err);
+
+ cnt = btf__find_by_glob_kind(prog->obj->btf_vmlinux, BTF_KIND_FUNC,
+ pattern, NULL, &ids);
+ if (cnt <= 0)
+ return ERR_PTR(-EINVAL);
+
+ link = calloc(1, sizeof(*link));
+ if (!link) {
+ err = -ENOMEM;
+ goto out_err;
+ }
+ link->detach = &bpf_link__detach_fd;
+
+ opts.multi.btf_ids = ids;
+ opts.multi.btf_ids_cnt = cnt;
+
+ attach_type = bpf_program__get_expected_attach_type(prog);
+ link_fd = bpf_link_create(prog_fd, 0, attach_type, &opts);
+ if (link_fd < 0) {
+ err = -errno;
+ goto out_err;
+ }
+ link->fd = link_fd;
+ free(ids);
+ return link;
+
+out_err:
+ free(link);
+ free(ids);
+ return ERR_PTR(err);
+}
+
+static struct bpf_link *attach_trace_multi(const struct bpf_program *prog, long cookie)
+{
+ return bpf_program__attach_multi(prog);
+}
+
struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
{
return bpf_program__attach_btf_id(prog);
--
2.31.1
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