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authorEelco Chaudron <echaudro@redhat.com>2020-02-20 13:26:35 +0000
committerAlexei Starovoitov <ast@kernel.org>2020-02-20 17:48:40 -0800
commitff26ce5cd7680ebc9c5446cda013e2087decc60f (patch)
tree13503f7c233736c8f10bd27795597cb48012dd71 /tools/lib
parentdd88aed92d017bed2a2c0023f22f0eef7cd29702 (diff)
libbpf: Add support for dynamic program attach target
Currently when you want to attach a trace program to a bpf program the section name needs to match the tracepoint/function semantics. However the addition of the bpf_program__set_attach_target() API allows you to specify the tracepoint/function dynamically. The call flow would look something like this: xdp_fd = bpf_prog_get_fd_by_id(id); trace_obj = bpf_object__open_file("func.o", NULL); prog = bpf_object__find_program_by_title(trace_obj, "fentry/myfunc"); bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY); bpf_program__set_attach_target(prog, xdp_fd, "xdpfilt_blk_all"); bpf_object__load(trace_obj) Signed-off-by: Eelco Chaudron <echaudro@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/158220519486.127661.7964708960649051384.stgit@xdp-tutorial
Diffstat (limited to 'tools/lib')
-rw-r--r--tools/lib/bpf/libbpf.c34
-rw-r--r--tools/lib/bpf/libbpf.h4
-rw-r--r--tools/lib/bpf/libbpf.map2
3 files changed, 36 insertions, 4 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 0eb10b681413..8f0c436d5880 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4937,8 +4937,8 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
{
int err = 0, fd, i, btf_id;
- if (prog->type == BPF_PROG_TYPE_TRACING ||
- prog->type == BPF_PROG_TYPE_EXT) {
+ if ((prog->type == BPF_PROG_TYPE_TRACING ||
+ prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) {
btf_id = libbpf_find_attach_btf_id(prog);
if (btf_id <= 0)
return btf_id;
@@ -6581,6 +6581,9 @@ static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name,
else
err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
+ if (err <= 0)
+ pr_warn("%s is not found in vmlinux BTF\n", name);
+
return err;
}
@@ -6653,8 +6656,6 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog)
err = __find_vmlinux_btf_id(prog->obj->btf_vmlinux,
name + section_defs[i].len,
attach_type);
- if (err <= 0)
- pr_warn("%s is not found in vmlinux BTF\n", name);
return err;
}
pr_warn("failed to identify btf_id based on ELF section name '%s'\n", name);
@@ -8130,6 +8131,31 @@ void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear)
}
}
+int bpf_program__set_attach_target(struct bpf_program *prog,
+ int attach_prog_fd,
+ const char *attach_func_name)
+{
+ int btf_id;
+
+ if (!prog || attach_prog_fd < 0 || !attach_func_name)
+ return -EINVAL;
+
+ if (attach_prog_fd)
+ btf_id = libbpf_find_prog_btf_id(attach_func_name,
+ attach_prog_fd);
+ else
+ btf_id = __find_vmlinux_btf_id(prog->obj->btf_vmlinux,
+ attach_func_name,
+ prog->expected_attach_type);
+
+ if (btf_id < 0)
+ return btf_id;
+
+ prog->attach_btf_id = btf_id;
+ prog->attach_prog_fd = attach_prog_fd;
+ return 0;
+}
+
int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz)
{
int err = 0, n, len, start, end = -1;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 3fe12c9d1f92..02fc58a21a7f 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -334,6 +334,10 @@ LIBBPF_API void
bpf_program__set_expected_attach_type(struct bpf_program *prog,
enum bpf_attach_type type);
+LIBBPF_API int
+bpf_program__set_attach_target(struct bpf_program *prog, int attach_prog_fd,
+ const char *attach_func_name);
+
LIBBPF_API bool bpf_program__is_socket_filter(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_tracepoint(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_raw_tracepoint(const struct bpf_program *prog);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 45be19c9d752..7b014c8cdece 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -237,4 +237,6 @@ LIBBPF_0.0.7 {
} LIBBPF_0.0.6;
LIBBPF_0.0.8 {
+ global:
+ bpf_program__set_attach_target;
} LIBBPF_0.0.7;