diff --git a/src/programs/probe.rs b/src/programs/probe.rs
index a554f455..6b9a29d4 100644
--- a/src/programs/probe.rs
+++ b/src/programs/probe.rs
@@ -291,7 +291,7 @@ fn resolve_symbol(path: &str, symbol: &str) -> Result<u64, ResolveSymbolError> {
         .ok_or_else(|| ResolveSymbolError::Unknown(symbol.to_string()))
 }
 
-pub fn read_sys_fs_perf_type(pmu: &str) -> Result<u32, ProgramError> {
+fn read_sys_fs_perf_type(pmu: &str) -> Result<u32, ProgramError> {
     let file = format!("/sys/bus/event_source/devices/{}/type", pmu);
 
     let perf_ty = fs::read_to_string(&file).map_err(|e| ProgramError::Other {
@@ -307,7 +307,7 @@ pub fn read_sys_fs_perf_type(pmu: &str) -> Result<u32, ProgramError> {
     Ok(perf_ty)
 }
 
-pub fn read_sys_fs_perf_ret_probe(pmu: &str) -> Result<u32, ProgramError> {
+fn read_sys_fs_perf_ret_probe(pmu: &str) -> Result<u32, ProgramError> {
     let file = format!("/sys/bus/event_source/devices/{}/format/retprobe", pmu);
 
     let data = fs::read_to_string(&file).map_err(|e| ProgramError::Other {
diff --git a/src/syscalls/bpf.rs b/src/syscalls/bpf.rs
index a4468cb8..af3e8f81 100644
--- a/src/syscalls/bpf.rs
+++ b/src/syscalls/bpf.rs
@@ -159,6 +159,7 @@ pub(crate) fn bpf_map_get_next_key<K>(
     }
 }
 
+// since kernel 5.7
 pub(crate) fn bpf_link_create(
     prog_fd: RawFd,
     target_fd: RawFd,