[PATCH bpf-next v2 5/9] libbpf: Add log_opts support for BPF_TRACE_ITER

[Leon Hwang <leon.hwang@linux.dev>]

Add iter.info and iter.len to pass iterator information separately from
log_opts. Keep the existing iter_info and iter_info_len fields working
for callers that do not request logs.

Thereafter, log_opts can work for iter link_create.

Meanwhile, add log_opts support for bpf_program__attach_iter() API.

Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
 tools/lib/bpf/bpf.c    | 23 +++++++++++++++++------
 tools/lib/bpf/bpf.h    |  8 ++++++++
 tools/lib/bpf/libbpf.c |  5 +++--
 tools/lib/bpf/libbpf.h |  3 ++-
 4 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 38dcb31e8c0e..ad6b356cc48c 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -808,11 +808,6 @@ int bpf_link_create(int prog_fd, int target_fd,
 	if (iter_info_len && attach_type != BPF_TRACE_ITER)
 		return libbpf_err(-EINVAL);
 
-	if (iter_info_len)
-		iter_info = OPTS_GET(opts, iter_info, (void *)0);
-	else
-		log_opts = OPTS_GET(opts, log_opts, (void *)0);
-
 	/* validate we don't have unexpected combinations of non-zero fields */
 	if (iter_info_len || target_btf_id) {
 		if (iter_info_len && target_btf_id)
@@ -821,6 +816,22 @@ int bpf_link_create(int prog_fd, int target_fd,
 			return libbpf_err(-EINVAL);
 	}
 
+	if (attach_type == BPF_TRACE_ITER) {
+		if (iter_info_len) {
+			iter_info = OPTS_GET(opts, iter_info, (void *)0);
+		} else {
+			log_opts = OPTS_GET(opts, log_opts, (void *)0);
+			iter_info = OPTS_GET(opts, iter.info, (void *)0);
+			iter_info_len = OPTS_GET(opts, iter.len, 0);
+			if (iter_info_len && target_btf_id)
+				return libbpf_err(-EINVAL);
+			if (!OPTS_ZEROED(opts, iter))
+				return libbpf_err(-EINVAL);
+		}
+	} else {
+		log_opts = OPTS_GET(opts, log_opts, (void *)0);
+	}
+
 	memset(&attr, 0, attr_sz);
 	attr.link_create.prog_fd = prog_fd;
 	attr.link_create.target_fd = target_fd;
@@ -970,7 +981,7 @@ int bpf_link_create(int prog_fd, int target_fd,
 			return libbpf_err(-EINVAL);
 		break;
 	default:
-		if (!OPTS_ZEROED(opts, iter_info_len))
+		if (!OPTS_ZEROED(opts, log_opts))
 			return libbpf_err(-EINVAL);
 		break;
 	}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index fe3b7fd8512b..2ac143fd1102 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -422,6 +422,10 @@ union bpf_iter_link_info; /* defined in up-to-date linux/bpf.h */
 struct bpf_link_create_opts {
 	size_t sz; /* size of this struct for forward/backward compatibility */
 	__u32 flags;
+	/*
+	 * iter_info and iter_info_len are deprecated, use iter.info and
+	 * iter.len instead.
+	 */
 	union {
 		union bpf_iter_link_info *iter_info;
 		struct bpf_log_opts *log_opts;
@@ -478,6 +482,10 @@ struct bpf_link_create_opts {
 			const __u64 *cookies;
 			__u32 cnt;
 		} tracing_multi;
+		struct {
+			union bpf_iter_link_info *info;
+			__u32 len;
+		} iter;
 	};
 	size_t :0;
 };
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 44134421bd7d..28830d198e9d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -14811,8 +14811,9 @@ bpf_program__attach_iter(const struct bpf_program *prog,
 	if (!OPTS_VALID(opts, bpf_iter_attach_opts))
 		return libbpf_err_ptr(-EINVAL);
 
-	link_create_opts.iter_info = OPTS_GET(opts, link_info, (void *)0);
-	link_create_opts.iter_info_len = OPTS_GET(opts, link_info_len, 0);
+	link_create_opts.log_opts = OPTS_GET(opts, log_opts, (void *)0);
+	link_create_opts.iter.info = OPTS_GET(opts, link_info, (void *)0);
+	link_create_opts.iter.len = OPTS_GET(opts, link_info_len, 0);
 
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 49f1120f4021..56300be81016 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1000,8 +1000,9 @@ struct bpf_iter_attach_opts {
 	size_t sz; /* size of this struct for forward/backward compatibility */
 	union bpf_iter_link_info *link_info;
 	__u32 link_info_len;
+	struct bpf_log_opts *log_opts;
 };
-#define bpf_iter_attach_opts__last_field link_info_len
+#define bpf_iter_attach_opts__last_field log_opts
 
 LIBBPF_API struct bpf_link *
 bpf_program__attach_iter(const struct bpf_program *prog,
-- 
2.55.0