[RFC PATCH v1 bpf-next 3/4] libbpf: Add bpf_struct_ops_associate_prog() API

[Amery Hung <ameryhung@gmail.com>]

Add low-level wrapper API for BPF_STRUCT_OPS_ASSOCIATE_PROG command in
bpf() syscall.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
---
 tools/lib/bpf/bpf.c      | 18 ++++++++++++++++++
 tools/lib/bpf/bpf.h      | 19 +++++++++++++++++++
 tools/lib/bpf/libbpf.map |  1 +
 3 files changed, 38 insertions(+)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 339b19797237..230fc2fa98f9 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -1397,3 +1397,21 @@ int bpf_prog_stream_read(int prog_fd, __u32 stream_id, void *buf, __u32 buf_len,
 	err = sys_bpf(BPF_PROG_STREAM_READ_BY_FD, &attr, attr_sz);
 	return libbpf_err_errno(err);
 }
+
+int bpf_struct_ops_associate_prog(int map_fd, int prog_fd,
+				  struct bpf_struct_ops_associate_prog_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, struct_ops_assoc_prog);
+	union bpf_attr attr;
+	int err;
+
+	if (!OPTS_VALID(opts, bpf_struct_ops_associate_prog_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.struct_ops_assoc_prog.map_fd = map_fd;
+	attr.struct_ops_assoc_prog.prog_fd = prog_fd;
+
+	err = sys_bpf(BPF_STRUCT_OPS_ASSOCIATE_PROG, &attr, attr_sz);
+	return libbpf_err_errno(err);
+}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index e983a3e40d61..99fe189ca7c6 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -733,6 +733,25 @@ struct bpf_prog_stream_read_opts {
 LIBBPF_API int bpf_prog_stream_read(int prog_fd, __u32 stream_id, void *buf, __u32 buf_len,
 				    struct bpf_prog_stream_read_opts *opts);
 
+struct bpf_struct_ops_associate_prog_opts {
+	size_t sz;
+	size_t :0;
+};
+#define bpf_struct_ops_associate_prog_opts__last_field sz
+/**
+ * @brief **bpf_struct_ops_associate_prog** associate a BPF program with a
+ * struct_ops map.
+ *
+ * @param map_fd FD for the struct_ops map to be associated with a BPF progam
+ * @param prog_fd FD for the BPF program
+ * @param opts optional options, can be NULL
+ *
+ * @return 0 on success; negative error code, otherwise (errno is also set to
+ * the error code)
+ */
+LIBBPF_API int bpf_struct_ops_associate_prog(int map_fd, int prog_fd,
+					     struct bpf_struct_ops_associate_prog_opts *opts);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 8ed8749907d4..3a156a663210 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -451,4 +451,5 @@ LIBBPF_1.7.0 {
 	global:
 		bpf_map__set_exclusive_program;
 		bpf_map__exclusive_program;
+		bpf_struct_ops_associate_prog;
 } LIBBPF_1.6.0;
-- 
2.47.3