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Message-ID: <20191107054644.1285697-17-ast@kernel.org>
Date: Wed, 6 Nov 2019 21:46:43 -0800
From: Alexei Starovoitov <ast@...nel.org>
To: <davem@...emloft.net>
CC: <daniel@...earbox.net>, <x86@...nel.org>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH v2 bpf-next 16/17] libbpf: Add support for attaching BPF programs to other BPF programs
Extend libbpf api to pass attach_prog_fd into bpf_object__open.
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
---
tools/include/uapi/linux/bpf.h | 1 +
tools/lib/bpf/bpf.c | 9 ++++--
tools/lib/bpf/bpf.h | 5 +++-
tools/lib/bpf/libbpf.c | 55 ++++++++++++++++++++++++++++++++--
tools/lib/bpf/libbpf.h | 3 +-
5 files changed, 65 insertions(+), 8 deletions(-)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 69c200e6e696..4842a134b202 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -425,6 +425,7 @@ union bpf_attr {
__aligned_u64 line_info; /* line info */
__u32 line_info_cnt; /* number of bpf_line_info records */
__u32 attach_btf_id; /* in-kernel BTF type id to attach to */
+ __u32 attach_prog_fd; /* 0 to attach to vmlinux */
};
struct { /* anonymous struct used by BPF_OBJ_* commands */
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index ca0d635b1d5e..fd556bb89446 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -228,10 +228,14 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
memset(&attr, 0, sizeof(attr));
attr.prog_type = load_attr->prog_type;
attr.expected_attach_type = load_attr->expected_attach_type;
- if (attr.prog_type == BPF_PROG_TYPE_TRACING)
+ if (attr.prog_type == BPF_PROG_TYPE_TRACING) {
attr.attach_btf_id = load_attr->attach_btf_id;
- else
+ if (load_attr->attach_prog_fd)
+ attr.attach_prog_fd = load_attr->attach_prog_fd;
+ } else {
attr.prog_ifindex = load_attr->prog_ifindex;
+ attr.kern_version = load_attr->kern_version;
+ }
attr.insn_cnt = (__u32)load_attr->insns_cnt;
attr.insns = ptr_to_u64(load_attr->insns);
attr.license = ptr_to_u64(load_attr->license);
@@ -245,7 +249,6 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
attr.log_size = 0;
}
- attr.kern_version = load_attr->kern_version;
attr.prog_btf_fd = load_attr->prog_btf_fd;
attr.func_info_rec_size = load_attr->func_info_rec_size;
attr.func_info_cnt = load_attr->func_info_cnt;
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 1c53bc5b4b3c..3c791fa8e68e 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -77,7 +77,10 @@ struct bpf_load_program_attr {
const struct bpf_insn *insns;
size_t insns_cnt;
const char *license;
- __u32 kern_version;
+ union {
+ __u32 kern_version;
+ __u32 attach_prog_fd;
+ };
union {
__u32 prog_ifindex;
__u32 attach_btf_id;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 4baaa14b4ca0..1df0d8798a03 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -189,6 +189,7 @@ struct bpf_program {
enum bpf_attach_type expected_attach_type;
__u32 attach_btf_id;
+ __u32 attach_prog_fd;
void *func_info;
__u32 func_info_rec_size;
__u32 func_info_cnt;
@@ -3681,8 +3682,13 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
load_attr.insns = insns;
load_attr.insns_cnt = insns_cnt;
load_attr.license = license;
- load_attr.kern_version = kern_version;
- load_attr.prog_ifindex = prog->prog_ifindex;
+ if (prog->type == BPF_PROG_TYPE_TRACING) {
+ load_attr.attach_prog_fd = prog->attach_prog_fd;
+ load_attr.attach_btf_id = prog->attach_btf_id;
+ } else {
+ load_attr.kern_version = kern_version;
+ load_attr.prog_ifindex = prog->prog_ifindex;
+ }
/* if .BTF.ext was loaded, kernel supports associated BTF for prog */
if (prog->obj->btf_ext)
btf_fd = bpf_object__btf_fd(prog->obj);
@@ -3697,7 +3703,6 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
load_attr.line_info_cnt = prog->line_info_cnt;
load_attr.log_level = prog->log_level;
load_attr.prog_flags = prog->prog_flags;
- load_attr.attach_btf_id = prog->attach_btf_id;
retry_load:
log_buf = malloc(log_buf_size);
@@ -3859,6 +3864,40 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level)
return 0;
}
+static int libbpf_get_prog_btf_id(u32 attach_prog_fd, const char *btf_name)
+{
+ struct bpf_prog_info_linear *info_linear;
+ struct bpf_prog_info *info;
+ struct btf *btf = NULL;
+ int err = -EINVAL;
+
+ info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0);
+ if (IS_ERR_OR_NULL(info_linear)) {
+ pr_warn("failed get_prog_info_linear for FD %d\n",
+ attach_prog_fd);
+ return -EINVAL;
+ }
+ info = &info_linear->info;
+ if (!info->btf_id) {
+ pr_warn("The target program doesn't have BTF\n");
+ goto out;
+ }
+ if (btf__get_from_id(info->btf_id, &btf)) {
+ pr_warn("Failed to get BTF of the program\n");
+ goto out;
+ }
+ err = btf__find_by_name(btf, btf_name);
+ btf__free(btf);
+ if (err <= 0) {
+ pr_warn("%s is not found in prog's BTF\n", btf_name);
+ goto out;
+ }
+ pr_warn("found %s's id %d\n", btf_name, err);
+out:
+ free(info_linear);
+ return err;
+}
+
static struct bpf_object *
__bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
struct bpf_object_open_opts *opts)
@@ -3869,6 +3908,7 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
const char *obj_name;
char tmp_name[64];
bool relaxed_maps;
+ __u32 attach_prog_fd;
int err;
if (elf_version(EV_CURRENT) == EV_NONE) {
@@ -3899,6 +3939,7 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
obj->relaxed_core_relocs = OPTS_GET(opts, relaxed_core_relocs, false);
relaxed_maps = OPTS_GET(opts, relaxed_maps, false);
pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
+ attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
CHECK_ERR(bpf_object__elf_init(obj), err, out);
CHECK_ERR(bpf_object__check_endianness(obj), err, out);
@@ -3924,6 +3965,14 @@ __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) {
+ if (attach_prog_fd) {
+ err = libbpf_get_prog_btf_id(attach_prog_fd, prog->section_name + 6);
+ if (err > 0) {
+ btf_id = err;
+ err = 0;
+ prog->attach_prog_fd = attach_prog_fd;
+ }
+ } else
err = libbpf_attach_btf_id_by_name(prog->section_name,
attach_type,
&btf_id);
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 9576aeadc421..abfda6c04d02 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -108,8 +108,9 @@ struct bpf_object_open_opts {
* auto-pinned to that path on load; defaults to "/sys/fs/bpf".
*/
const char *pin_root_path;
+ __u32 attach_prog_fd;
};
-#define bpf_object_open_opts__last_field pin_root_path
+#define bpf_object_open_opts__last_field attach_prog_fd
LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
LIBBPF_API struct bpf_object *
--
2.23.0
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