PTR_TO_TCP_SOCK_OR_NULL, /* reg points to struct tcp_sock or NULL */
PTR_TO_TP_BUFFER, /* reg points to a writable raw tp's buffer */
PTR_TO_XDP_SOCK, /* reg points to struct xdp_sock */
- PTR_TO_BTF_ID, /* reg points to kernel struct */
- PTR_TO_BTF_ID_OR_NULL, /* reg points to kernel struct or NULL */
+ /* PTR_TO_BTF_ID points to a kernel struct that does not need
+ * to be null checked by the BPF program. This does not imply the
+ * pointer is _not_ null and in practice this can easily be a null
+ * pointer when reading pointer chains. The assumption is program
+ * context will handle null pointer dereference typically via fault
+ * handling. The verifier must keep this in mind and can make no
+ * assumptions about null or non-null when doing branch analysis.
+ * Further, when passed into helpers the helpers can not, without
+ * additional context, assume the value is non-null.
+ */
+ PTR_TO_BTF_ID,
+ /* PTR_TO_BTF_ID_OR_NULL points to a kernel struct that has not
+ * been checked for null. Used primarily to inform the verifier
+ * an explicit null check is required for this struct.
+ */
+ PTR_TO_BTF_ID_OR_NULL,
PTR_TO_MEM, /* reg points to valid memory region */
PTR_TO_MEM_OR_NULL, /* reg points to valid memory region or NULL */
PTR_TO_RDONLY_BUF, /* reg points to a readonly buffer */