kernel: add lockdep expression

Lockdep is the kernel's locking validation/debugging tool and has seen
heavy pro-active usage and development. In Linux 3.14, it's now
available directly to userspace for the same purpose. It comes with a
convenient utility to LD_PRELOAD a shared library for validation, or a
user-space API to link to directly.

Signed-off-by: Austin Seipp <aseipp@pobox.com>

pkgs/os-specific/linux/kernel/lockdep.nix

@@ -0,0 +1,25 @@
+{ stdenv, kernel }:
+
+assert stdenv.lib.versionAtLeast kernel.version "3.14";
+stdenv.mkDerivation {
+  name = "lockdep-linux-${kernel.version}";
+  inherit (kernel) src patches;
+
+  preConfigure = "cd tools/lib/lockdep";
+  installPhase = ''
+    mkdir -p $out/bin $out/lib $out/include
+
+    cp -R include/liblockdep $out/include
+    make install DESTDIR=$out prefix=""
+
+    substituteInPlace $out/bin/lockdep --replace "./liblockdep.so" "$out/lib/liblockdep.so"
+  '';
+
+  meta = {
+    description = "User-space locking validation via the kernel";
+    homepage    = "https://kernel.org/";
+    license     = stdenv.lib.licenses.gpl2;
+    platforms   = stdenv.lib.platforms.linux;
+    maintainers = [ stdenv.lib.maintainers.thoughtpolice ];
+  };
+}

pkgs/top-level/all-packages.nix

@@ -7031,6 +7031,8 @@ let
 
     perf = callPackage ../os-specific/linux/kernel/perf.nix { };
 
+    lockdep = callPackage ../os-specific/linux/kernel/lockdep.nix { };
+
     psmouse_alps = callPackage ../os-specific/linux/psmouse-alps { };
 
     spl = callPackage ../os-specific/linux/spl/default.nix { };