bpftool: Use bpf_obj_get_info_by_fd directly

To prepare for impending deprecation of libbpf's
bpf_program__get_prog_info_linear, migrate uses of this function to use
bpf_obj_get_info_by_fd.

Since the profile_target_name and dump_prog_id_as_func_ptr helpers were
only looking at the first func_info, avoid grabbing the rest to save a
malloc. For do_dump, add a more full-featured helper, but avoid
free/realloc of buffer when possible for multi-prog dumps.

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20211101224357.2651181-3-davemarchevsky@fb.com

1 files changed, 24 insertions, 16 deletions

diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
index 6934e8634b94..f5dddf8ef404 100644
--- a/tools/bpf/bpftool/btf_dumper.c
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -32,14 +32,16 @@ static int dump_prog_id_as_func_ptr(const struct btf_dumper *d,
 				    const struct btf_type *func_proto,
 				    __u32 prog_id)
 {
-	struct bpf_prog_info_linear *prog_info = NULL;
 	const struct btf_type *func_type;
+	int prog_fd = -1, func_sig_len;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	const char *prog_name = NULL;
-	struct bpf_func_info *finfo;
 	struct btf *prog_btf = NULL;
-	struct bpf_prog_info *info;
-	int prog_fd, func_sig_len;
+	struct bpf_func_info finfo;
+	__u32 finfo_rec_size;
 	char prog_str[1024];
+	int err;
 
 	/* Get the ptr's func_proto */
 	func_sig_len = btf_dump_func(d->btf, prog_str, func_proto, NULL, 0,
@@ -55,22 +57,27 @@ static int dump_prog_id_as_func_ptr(const struct btf_dumper *d,
 	if (prog_fd < 0)
 		goto print;
 
-	prog_info = bpf_program__get_prog_info_linear(prog_fd,
-						1UL << BPF_PROG_INFO_FUNC_INFO);
-	close(prog_fd);
-	if (IS_ERR(prog_info)) {
-		prog_info = NULL;
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err)
 		goto print;
-	}
-	info = &prog_info->info;
 
-	if (!info->btf_id || !info->nr_func_info)
+	if (!info.btf_id || !info.nr_func_info)
+		goto print;
+
+	finfo_rec_size = info.func_info_rec_size;
+	memset(&info, 0, sizeof(info));
+	info.nr_func_info = 1;
+	info.func_info_rec_size = finfo_rec_size;
+	info.func_info = ptr_to_u64(&finfo);
+
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err)
 		goto print;
-	prog_btf = btf__load_from_kernel_by_id(info->btf_id);
+
+	prog_btf = btf__load_from_kernel_by_id(info.btf_id);
 	if (libbpf_get_error(prog_btf))
 		goto print;
-	finfo = u64_to_ptr(info->func_info);
-	func_type = btf__type_by_id(prog_btf, finfo->type_id);
+	func_type = btf__type_by_id(prog_btf, finfo.type_id);
 	if (!func_type || !btf_is_func(func_type))
 		goto print;
 
@@ -92,7 +99,8 @@ print:
 	prog_str[sizeof(prog_str) - 1] = '\0';
 	jsonw_string(d->jw, prog_str);
 	btf__free(prog_btf);
-	free(prog_info);
+	if (prog_fd >= 0)
+		close(prog_fd);
 	return 0;
 }