Commit 2c3a3681 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'set_attach_target' 



Eelco Chaudron says:

====================
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)

v1 -> v2: Remove requirement for attach type hint in API
v2 -> v3: Moved common warning to __find_vmlinux_btf_id, requested by Andrii
          Updated the xdp_bpf2bpf test to use this new API
v3 -> v4: Split up patch, update libbpf.map version
v4 -> v5: Fix return code, and prog assignment in test case
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 53276446 933ce62d

tools/lib/bpf/libbpf.c

+30 −4
Original line number Diff line number Diff line
@@ -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;

tools/lib/bpf/libbpf.h

+4 −0
Original line number Diff line number Diff line
@@ -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);

tools/lib/bpf/libbpf.map

+5 −0
Original line number Diff line number Diff line
@@ -235,3 +235,8 @@ LIBBPF_0.0.7 { 
		btf__align_of;

		libbpf_find_kernel_btf;

} LIBBPF_0.0.6;



LIBBPF_0.0.8 {

	global:

		bpf_program__set_attach_target;

} LIBBPF_0.0.7;

tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c

+13 −3
Original line number Diff line number Diff line
@@ -14,7 +14,7 @@ void test_xdp_bpf2bpf(void) 
	struct test_xdp *pkt_skel = NULL;

	struct test_xdp_bpf2bpf *ftrace_skel = NULL;

	struct vip key4 = {.protocol = 6, .family = AF_INET};

	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);

	struct bpf_program *prog;



	/* Load XDP program to introspect */

	pkt_skel = test_xdp__open_and_load();
@@ -27,11 +27,21 @@ void test_xdp_bpf2bpf(void) 
	bpf_map_update_elem(map_fd, &key4, &value4, 0);



	/* Load trace program */

	opts.attach_prog_fd = pkt_fd,

	ftrace_skel = test_xdp_bpf2bpf__open_opts(&opts);

	ftrace_skel = test_xdp_bpf2bpf__open();

	if (CHECK(!ftrace_skel, "__open", "ftrace skeleton failed\n"))

		goto out;



	/* Demonstrate the bpf_program__set_attach_target() API rather than

	 * the load with options, i.e. opts.attach_prog_fd.

	 */

	prog = ftrace_skel->progs.trace_on_entry;

	bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY);

	bpf_program__set_attach_target(prog, pkt_fd, "_xdp_tx_iptunnel");



	prog = ftrace_skel->progs.trace_on_exit;

	bpf_program__set_expected_attach_type(prog, BPF_TRACE_FEXIT);

	bpf_program__set_attach_target(prog, pkt_fd, "_xdp_tx_iptunnel");



	err = test_xdp_bpf2bpf__load(ftrace_skel);

	if (CHECK(err, "__load", "ftrace skeleton failed\n"))

		goto out;

tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c

+2 −2
Original line number Diff line number Diff line
@@ -28,7 +28,7 @@ struct xdp_buff { 
} __attribute__((preserve_access_index));



__u64 test_result_fentry = 0;

SEC("fentry/_xdp_tx_iptunnel")

SEC("fentry/FUNC")

int BPF_PROG(trace_on_entry, struct xdp_buff *xdp)

{

	test_result_fentry = xdp->rxq->dev->ifindex;
@@ -36,7 +36,7 @@ int BPF_PROG(trace_on_entry, struct xdp_buff *xdp) 
}



__u64 test_result_fexit = 0;

SEC("fexit/_xdp_tx_iptunnel")

SEC("fexit/FUNC")

int BPF_PROG(trace_on_exit, struct xdp_buff *xdp, int ret)

{

	test_result_fexit = ret;

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