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Message-ID: <20191102220025.2475981-5-ast@kernel.org>
Date: Sat, 2 Nov 2019 15:00:22 -0700
From: Alexei Starovoitov <ast@...nel.org>
To: <davem@...emloft.net>
CC: <daniel@...earbox.net>, <peterz@...radead.org>,
<rostedt@...dmis.org>, <x86@...nel.org>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH bpf-next 4/7] libbpf: Add support to attach to fentry/fexit tracing progs
Teach libbpf to recognize tracing programs types and attach them to
fentry/fexit.
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
---
tools/include/uapi/linux/bpf.h | 2 ++
tools/lib/bpf/libbpf.c | 55 +++++++++++++++++++++++++++++-----
tools/lib/bpf/libbpf.h | 2 ++
tools/lib/bpf/libbpf.map | 1 +
4 files changed, 53 insertions(+), 7 deletions(-)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index df6809a76404..69c200e6e696 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -201,6 +201,8 @@ enum bpf_attach_type {
BPF_CGROUP_GETSOCKOPT,
BPF_CGROUP_SETSOCKOPT,
BPF_TRACE_RAW_TP,
+ BPF_TRACE_FENTRY,
+ BPF_TRACE_FEXIT,
__MAX_BPF_ATTACH_TYPE
};
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7aa2a2a22cef..03e784f36dd9 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3744,7 +3744,7 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level)
return 0;
}
-static int libbpf_attach_btf_id_by_name(const char *name, __u32 *btf_id);
+static int libbpf_attach_btf_id_by_name(const char *name, __u32 *btf_id, bool raw_tp);
static struct bpf_object *
__bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
@@ -3811,7 +3811,9 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
bpf_program__set_type(prog, prog_type);
bpf_program__set_expected_attach_type(prog, attach_type);
if (prog_type == BPF_PROG_TYPE_TRACING) {
- err = libbpf_attach_btf_id_by_name(prog->section_name, &btf_id);
+ err = libbpf_attach_btf_id_by_name(prog->section_name,
+ &btf_id,
+ attach_type == BPF_TRACE_RAW_TP);
if (err)
goto out;
prog->attach_btf_id = btf_id;
@@ -4813,6 +4815,10 @@ static const struct {
BPF_PROG_SEC("raw_tp/", BPF_PROG_TYPE_RAW_TRACEPOINT),
BPF_PROG_BTF("tp_btf/", BPF_PROG_TYPE_TRACING,
BPF_TRACE_RAW_TP),
+ BPF_PROG_BTF("fentry/", BPF_PROG_TYPE_TRACING,
+ BPF_TRACE_FENTRY),
+ BPF_PROG_BTF("fexit/", BPF_PROG_TYPE_TRACING,
+ BPF_TRACE_FEXIT),
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),
@@ -4930,7 +4936,7 @@ int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
}
#define BTF_PREFIX "btf_trace_"
-static int libbpf_attach_btf_id_by_name(const char *name, __u32 *btf_id)
+static int libbpf_attach_btf_id_by_name(const char *name, __u32 *btf_id, bool raw_tp)
{
struct btf *btf = bpf_core_find_kernel_btf();
char raw_tp_btf_name[128] = BTF_PREFIX;
@@ -4950,10 +4956,14 @@ static int libbpf_attach_btf_id_by_name(const char *name, __u32 *btf_id)
continue;
if (strncmp(name, section_names[i].sec, section_names[i].len))
continue;
- /* prepend "btf_trace_" prefix per kernel convention */
- strncat(dst, name + section_names[i].len,
- sizeof(raw_tp_btf_name) - sizeof(BTF_PREFIX));
- ret = btf__find_by_name(btf, raw_tp_btf_name);
+ if (!raw_tp) {
+ ret = btf__find_by_name(btf, name + section_names[i].len);
+ } else {
+ /* prepend "btf_trace_" prefix per kernel convention */
+ strncat(dst, name + section_names[i].len,
+ sizeof(raw_tp_btf_name) - sizeof(BTF_PREFIX));
+ ret = btf__find_by_name(btf, raw_tp_btf_name);
+ }
if (ret <= 0) {
pr_warn("%s is not found in vmlinux BTF\n", dst);
goto out;
@@ -5594,6 +5604,37 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
return (struct bpf_link *)link;
}
+struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
+{
+ char errmsg[STRERR_BUFSIZE];
+ struct bpf_link_fd *link;
+ int prog_fd, pfd;
+
+ 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 = malloc(sizeof(*link));
+ if (!link)
+ return ERR_PTR(-ENOMEM);
+ link->link.destroy = &bpf_link__destroy_fd;
+
+ pfd = bpf_raw_tracepoint_open(NULL, prog_fd);
+ if (pfd < 0) {
+ pfd = -errno;
+ free(link);
+ pr_warn("program '%s': failed to attach to trace: %s\n",
+ bpf_program__title(prog, false),
+ libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+ return ERR_PTR(pfd);
+ }
+ link->fd = pfd;
+ return (struct bpf_link *)link;
+}
+
enum bpf_perf_event_ret
bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
void **copy_mem, size_t *copy_size,
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 6ddc0419337b..0f53b0e0e135 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -248,6 +248,8 @@ LIBBPF_API struct bpf_link *
bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
const char *tp_name);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_trace(struct bpf_program *prog);
struct bpf_insn;
/*
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 86173cbb159d..f7b4e062d704 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -198,6 +198,7 @@ LIBBPF_0.0.6 {
bpf_map__set_pin_path;
bpf_object__open_file;
bpf_object__open_mem;
+ bpf_program__attach_trace;
bpf_program__get_expected_attach_type;
bpf_program__get_type;
bpf_program__is_tracing;
--
2.23.0
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