[RFC,bpf-next,13/14] libbpf: Add bpf_static_key_update() API

Commit Message

Anton Protopopov March 18, 2025, 2:33 p.m. UTC

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

Signed-off-by: Anton Protopopov <[e-mail]>
---
 tools/lib/bpf/bpf.c      | 17 +++++++++++++++++
 tools/lib/bpf/bpf.h      | 19 +++++++++++++++++++
 tools/lib/bpf/libbpf.map |  1 +
 3 files changed, 37 insertions(+)

Patch

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index a9c3e33d0f8a..330d9523fc2b 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -1331,3 +1331,20 @@  int bpf_token_create(int bpffs_fd, struct bpf_token_create_opts *opts)
 	fd = sys_bpf_fd(BPF_TOKEN_CREATE, &attr, attr_sz);
 	return libbpf_err_errno(fd);
 }
+
+int bpf_static_key_update(int map_fd, struct bpf_static_key_update_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, static_key);
+	union bpf_attr attr;
+	int ret;
+
+	if (!OPTS_VALID(opts, bpf_static_key_update_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.static_key.map_fd = map_fd;
+	attr.static_key.on = OPTS_GET(opts, on, 0);
+
+	ret = sys_bpf(BPF_STATIC_KEY_UPDATE, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 777627d33d25..c76abfda85f8 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -704,6 +704,25 @@  struct bpf_token_create_opts {
 LIBBPF_API int bpf_token_create(int bpffs_fd,
 				struct bpf_token_create_opts *opts);
 
+struct bpf_static_key_update_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u32 on;
+	size_t :0;
+};
+#define bpf_static_key_update_opts__last_field on
+
+/**
+ * @brief **bpf_static_key_update()** updates the value of a static key
+ *
+ * @param map_fd FD for the static key.
+ * @param opts optional BPF token creation options, can be NULL
+ *
+ * @return 0 on success; negative error code, otherwise (errno
+ * is also set to the error code)
+ */
+LIBBPF_API int bpf_static_key_update(int map_fd,
+				     struct bpf_static_key_update_opts *opts);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index d8b71f22f197..fc8f01d5804a 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -439,4 +439,5 @@  LIBBPF_1.6.0 {
 		bpf_object__prepare;
 		btf__add_decl_attr;
 		btf__add_type_attr;
+		bpf_static_key_update;
 } LIBBPF_1.5.0;