Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/bpf/bpftool/Documentation/bpftool-perf.rst b/tools/bpf/bpftool/Documentation/bpftool-perf.rst
index e3eb0ea..e252bd0 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-perf.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-perf.rst
@@ -43,7 +43,7 @@
 	-h, --help
 		  Print short generic help message (similar to **bpftool help**).
 
-	-v, --version
+	-V, --version
 		  Print version number (similar to **bpftool version**).
 
 	-j, --json
@@ -53,6 +53,10 @@
 	-p, --pretty
 		  Generate human-readable JSON output. Implies **-j**.
 
+	-d, --debug
+		  Print all logs available from libbpf, including debug-level
+		  information.
+
 EXAMPLES
 ========
 
@@ -78,4 +82,12 @@
 
 SEE ALSO
 ========
-	**bpftool**\ (8), **bpftool-prog**\ (8), **bpftool-map**\ (8)
+	**bpf**\ (2),
+	**bpf-helpers**\ (7),
+	**bpftool**\ (8),
+	**bpftool-prog**\ (8),
+	**bpftool-map**\ (8),
+	**bpftool-cgroup**\ (8),
+	**bpftool-feature**\ (8),
+	**bpftool-net**\ (8),
+	**bpftool-btf**\ (8)