License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

58 files changed, 58 insertions, 0 deletions

diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
index 1e83e3c..a13e9c7 100644
--- a/tools/lib/api/Makefile
+++ b/tools/lib/api/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 include ../../scripts/Makefile.include
 include ../../scripts/utilities.mak		# QUIET_CLEAN
 
diff --git a/tools/lib/api/cpu.c b/tools/lib/api/cpu.c
index 8c64893..4af6d4b 100644
--- a/tools/lib/api/cpu.c
+++ b/tools/lib/api/cpu.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 
 #include "cpu.h"
diff --git a/tools/lib/api/cpu.h b/tools/lib/api/cpu.h
index 81e9d39..90a102f 100644
--- a/tools/lib/api/cpu.h
+++ b/tools/lib/api/cpu.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __API_CPU__
 #define __API_CPU__
 
diff --git a/tools/lib/api/debug-internal.h b/tools/lib/api/debug-internal.h
index 188f7880..80c7834 100644
--- a/tools/lib/api/debug-internal.h
+++ b/tools/lib/api/debug-internal.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __API_DEBUG_INTERNAL_H__
 #define __API_DEBUG_INTERNAL_H__
 
diff --git a/tools/lib/api/debug.c b/tools/lib/api/debug.c
index 5fa5cf5..69b1ba3 100644
--- a/tools/lib/api/debug.c
+++ b/tools/lib/api/debug.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 #include <stdarg.h>
 #include "debug.h"
diff --git a/tools/lib/api/debug.h b/tools/lib/api/debug.h
index a0872f6..3684dd6 100644
--- a/tools/lib/api/debug.h
+++ b/tools/lib/api/debug.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __API_DEBUG_H__
 #define __API_DEBUG_H__
 
diff --git a/tools/lib/api/fd/array.h b/tools/lib/api/fd/array.h
index 71287dd..b39557d 100644
--- a/tools/lib/api/fd/array.h
+++ b/tools/lib/api/fd/array.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __API_FD_ARRAY__
 #define __API_FD_ARRAY__
 
diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
index a7ecf8f..b24afc0 100644
--- a/tools/lib/api/fs/fs.c
+++ b/tools/lib/api/fs/fs.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <ctype.h>
 #include <errno.h>
 #include <limits.h>
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
index 4560534..dda49de 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __API_FS__
 #define __API_FS__
 
diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
index 3e606b9..7b7fd0b 100644
--- a/tools/lib/api/fs/tracing_path.c
+++ b/tools/lib/api/fs/tracing_path.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #ifndef _GNU_SOURCE
 # define _GNU_SOURCE
 #endif
diff --git a/tools/lib/api/fs/tracing_path.h b/tools/lib/api/fs/tracing_path.h
index 3f233ac..0066f06 100644
--- a/tools/lib/api/fs/tracing_path.h
+++ b/tools/lib/api/fs/tracing_path.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __API_FS_TRACING_PATH_H
 #define __API_FS_TRACING_PATH_H
 
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index d2441db..4555304 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 # Most of this file is copied from tools/lib/traceevent/Makefile
 
 BPF_VERSION = 0
diff --git a/tools/lib/hweight.c b/tools/lib/hweight.c
index 0b859b8..a16ebf5 100644
--- a/tools/lib/hweight.c
+++ b/tools/lib/hweight.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/bitops.h>
 #include <asm/types.h>
 
diff --git a/tools/lib/lockdep/Makefile b/tools/lib/lockdep/Makefile
index ed9ace5..9b0ca3a 100644
--- a/tools/lib/lockdep/Makefile
+++ b/tools/lib/lockdep/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 # file format version
 FILE_VERSION = 1
 
diff --git a/tools/lib/lockdep/common.c b/tools/lib/lockdep/common.c
index d1c89cc..5c3b58c 100644
--- a/tools/lib/lockdep/common.c
+++ b/tools/lib/lockdep/common.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stddef.h>
 #include <stdbool.h>
 #include <linux/compiler.h>
diff --git a/tools/lib/lockdep/include/liblockdep/common.h b/tools/lib/lockdep/include/liblockdep/common.h
index 6e66277..8862da8 100644
--- a/tools/lib/lockdep/include/liblockdep/common.h
+++ b/tools/lib/lockdep/include/liblockdep/common.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LIBLOCKDEP_COMMON_H
 #define _LIBLOCKDEP_COMMON_H
 
diff --git a/tools/lib/lockdep/include/liblockdep/mutex.h b/tools/lib/lockdep/include/liblockdep/mutex.h
index ee53a42..a80ac39 100644
--- a/tools/lib/lockdep/include/liblockdep/mutex.h
+++ b/tools/lib/lockdep/include/liblockdep/mutex.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LIBLOCKDEP_MUTEX_H
 #define _LIBLOCKDEP_MUTEX_H
 
diff --git a/tools/lib/lockdep/include/liblockdep/rwlock.h b/tools/lib/lockdep/include/liblockdep/rwlock.h
index 4ec03f8..a96c3bf 100644
--- a/tools/lib/lockdep/include/liblockdep/rwlock.h
+++ b/tools/lib/lockdep/include/liblockdep/rwlock.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LIBLOCKDEP_RWLOCK_H
 #define _LIBLOCKDEP_RWLOCK_H
 
diff --git a/tools/lib/lockdep/lockdep.c b/tools/lib/lockdep/lockdep.c
index ced6d74..6002fcf 100644
--- a/tools/lib/lockdep/lockdep.c
+++ b/tools/lib/lockdep/lockdep.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/lockdep.h>
 #include <stdlib.h>
 
diff --git a/tools/lib/lockdep/preload.c b/tools/lib/lockdep/preload.c
index 6a2d3c5..76245d1 100644
--- a/tools/lib/lockdep/preload.c
+++ b/tools/lib/lockdep/preload.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #define _GNU_SOURCE
 #include <pthread.h>
 #include <stdio.h>
diff --git a/tools/lib/lockdep/run_tests.sh b/tools/lib/lockdep/run_tests.sh
index f9b9409..2e570a1 100755
--- a/tools/lib/lockdep/run_tests.sh
+++ b/tools/lib/lockdep/run_tests.sh
@@ -1,4 +1,5 @@
 #! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
 
 make &> /dev/null
 
diff --git a/tools/lib/lockdep/tests/AA.c b/tools/lib/lockdep/tests/AA.c
index 18211a5..63c7ce9 100644
--- a/tools/lib/lockdep/tests/AA.c
+++ b/tools/lib/lockdep/tests/AA.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/mutex.h>
 
 int main(void)
diff --git a/tools/lib/lockdep/tests/ABA.c b/tools/lib/lockdep/tests/ABA.c
index 0f782ff..efa39b2 100644
--- a/tools/lib/lockdep/tests/ABA.c
+++ b/tools/lib/lockdep/tests/ABA.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/mutex.h>
 
 void main(void)
diff --git a/tools/lib/lockdep/tests/ABBA.c b/tools/lib/lockdep/tests/ABBA.c
index 07f0e29d..1460afd 100644
--- a/tools/lib/lockdep/tests/ABBA.c
+++ b/tools/lib/lockdep/tests/ABBA.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/mutex.h>
 #include "common.h"
 
diff --git a/tools/lib/lockdep/tests/ABBA_2threads.c b/tools/lib/lockdep/tests/ABBA_2threads.c
index cd807d7..39325ef 100644
--- a/tools/lib/lockdep/tests/ABBA_2threads.c
+++ b/tools/lib/lockdep/tests/ABBA_2threads.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 #include <pthread.h>
 
diff --git a/tools/lib/lockdep/tests/ABBCCA.c b/tools/lib/lockdep/tests/ABBCCA.c
index 843db09..a54c1b2 100644
--- a/tools/lib/lockdep/tests/ABBCCA.c
+++ b/tools/lib/lockdep/tests/ABBCCA.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/mutex.h>
 #include "common.h"
 
diff --git a/tools/lib/lockdep/tests/ABBCCDDA.c b/tools/lib/lockdep/tests/ABBCCDDA.c
index 33620e2..aa5d194 100644
--- a/tools/lib/lockdep/tests/ABBCCDDA.c
+++ b/tools/lib/lockdep/tests/ABBCCDDA.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/mutex.h>
 #include "common.h"
 
diff --git a/tools/lib/lockdep/tests/ABCABC.c b/tools/lib/lockdep/tests/ABCABC.c
index 3fee51e..b54a08e 100644
--- a/tools/lib/lockdep/tests/ABCABC.c
+++ b/tools/lib/lockdep/tests/ABCABC.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/mutex.h>
 #include "common.h"
 
diff --git a/tools/lib/lockdep/tests/ABCDBCDA.c b/tools/lib/lockdep/tests/ABCDBCDA.c
index 427ba56..a567422 100644
--- a/tools/lib/lockdep/tests/ABCDBCDA.c
+++ b/tools/lib/lockdep/tests/ABCDBCDA.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/mutex.h>
 #include "common.h"
 
diff --git a/tools/lib/lockdep/tests/ABCDBDDA.c b/tools/lib/lockdep/tests/ABCDBDDA.c
index 680c6cf..238a335 100644
--- a/tools/lib/lockdep/tests/ABCDBDDA.c
+++ b/tools/lib/lockdep/tests/ABCDBDDA.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/mutex.h>
 #include "common.h"
 
diff --git a/tools/lib/lockdep/tests/WW.c b/tools/lib/lockdep/tests/WW.c
index d44f77d..eee88df 100644
--- a/tools/lib/lockdep/tests/WW.c
+++ b/tools/lib/lockdep/tests/WW.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/rwlock.h>
 
 void main(void)
diff --git a/tools/lib/lockdep/tests/common.h b/tools/lib/lockdep/tests/common.h
index d89e94d..3026c29 100644
--- a/tools/lib/lockdep/tests/common.h
+++ b/tools/lib/lockdep/tests/common.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LIBLOCKDEP_TEST_COMMON_H
 #define _LIBLOCKDEP_TEST_COMMON_H
 
diff --git a/tools/lib/lockdep/tests/unlock_balance.c b/tools/lib/lockdep/tests/unlock_balance.c
index 0bc62de..34cf32f 100644
--- a/tools/lib/lockdep/tests/unlock_balance.c
+++ b/tools/lib/lockdep/tests/unlock_balance.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <liblockdep/mutex.h>
 
 void main(void)
diff --git a/tools/lib/str_error_r.c b/tools/lib/str_error_r.c
index 503ae07..d6d6553 100644
--- a/tools/lib/str_error_r.c
+++ b/tools/lib/str_error_r.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #undef _GNU_SOURCE
 #include <string.h>
 #include <stdio.h>
diff --git a/tools/lib/string.c b/tools/lib/string.c
index a4246f1..93b3d4b 100644
--- a/tools/lib/string.c
+++ b/tools/lib/string.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  *  linux/tools/lib/string.c
  *
diff --git a/tools/lib/subcmd/Makefile b/tools/lib/subcmd/Makefile
index 7e9f03c..95563b8 100644
--- a/tools/lib/subcmd/Makefile
+++ b/tools/lib/subcmd/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 include ../../scripts/Makefile.include
 include ../../scripts/utilities.mak		# QUIET_CLEAN
 
diff --git a/tools/lib/subcmd/exec-cmd.c b/tools/lib/subcmd/exec-cmd.c
index 1ae833a..33e94fb 100644
--- a/tools/lib/subcmd/exec-cmd.c
+++ b/tools/lib/subcmd/exec-cmd.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/compiler.h>
 #include <linux/string.h>
 #include <sys/types.h>
diff --git a/tools/lib/subcmd/exec-cmd.h b/tools/lib/subcmd/exec-cmd.h
index 5d08bda..aba591b 100644
--- a/tools/lib/subcmd/exec-cmd.h
+++ b/tools/lib/subcmd/exec-cmd.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __SUBCMD_EXEC_CMD_H
 #define __SUBCMD_EXEC_CMD_H
 
diff --git a/tools/lib/subcmd/help.c b/tools/lib/subcmd/help.c
index 0310520..2859f10 100644
--- a/tools/lib/subcmd/help.c
+++ b/tools/lib/subcmd/help.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/tools/lib/subcmd/help.h b/tools/lib/subcmd/help.h
index 9bd4223..355c066c 100644
--- a/tools/lib/subcmd/help.h
+++ b/tools/lib/subcmd/help.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __SUBCMD_HELP_H
 #define __SUBCMD_HELP_H
 
diff --git a/tools/lib/subcmd/pager.c b/tools/lib/subcmd/pager.c
index 6518bea..5ba754d 100644
--- a/tools/lib/subcmd/pager.c
+++ b/tools/lib/subcmd/pager.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <sys/select.h>
 #include <stdlib.h>
 #include <stdio.h>
diff --git a/tools/lib/subcmd/pager.h b/tools/lib/subcmd/pager.h
index 623f554..f1a53cf 100644
--- a/tools/lib/subcmd/pager.h
+++ b/tools/lib/subcmd/pager.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __SUBCMD_PAGER_H
 #define __SUBCMD_PAGER_H
 
diff --git a/tools/lib/subcmd/parse-options.c b/tools/lib/subcmd/parse-options.c
index 2bd6fd0..f6a1bab 100644
--- a/tools/lib/subcmd/parse-options.c
+++ b/tools/lib/subcmd/parse-options.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/compiler.h>
 #include <linux/string.h>
 #include <linux/types.h>
diff --git a/tools/lib/subcmd/parse-options.h b/tools/lib/subcmd/parse-options.h
index f054ca1..92fdbe1 100644
--- a/tools/lib/subcmd/parse-options.h
+++ b/tools/lib/subcmd/parse-options.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __SUBCMD_PARSE_OPTIONS_H
 #define __SUBCMD_PARSE_OPTIONS_H
 
diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
index 911f839..5cdac21 100644
--- a/tools/lib/subcmd/run-command.c
+++ b/tools/lib/subcmd/run-command.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
diff --git a/tools/lib/subcmd/run-command.h b/tools/lib/subcmd/run-command.h
index fe2befe..17d969c 100644
--- a/tools/lib/subcmd/run-command.h
+++ b/tools/lib/subcmd/run-command.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __SUBCMD_RUN_COMMAND_H
 #define __SUBCMD_RUN_COMMAND_H
 
diff --git a/tools/lib/subcmd/sigchain.c b/tools/lib/subcmd/sigchain.c
index 3537c34..f0fe3db 100644
--- a/tools/lib/subcmd/sigchain.c
+++ b/tools/lib/subcmd/sigchain.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <signal.h>
 #include "subcmd-util.h"
 #include "sigchain.h"
diff --git a/tools/lib/subcmd/sigchain.h b/tools/lib/subcmd/sigchain.h
index 0c919f2..1ec663a 100644
--- a/tools/lib/subcmd/sigchain.h
+++ b/tools/lib/subcmd/sigchain.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __SUBCMD_SIGCHAIN_H
 #define __SUBCMD_SIGCHAIN_H
 
diff --git a/tools/lib/subcmd/subcmd-config.c b/tools/lib/subcmd/subcmd-config.c
index d017c72..84a7cf6 100644
--- a/tools/lib/subcmd/subcmd-config.c
+++ b/tools/lib/subcmd/subcmd-config.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include "subcmd-config.h"
 
 #define UNDEFINED "SUBCMD_HAS_NOT_BEEN_INITIALIZED"
diff --git a/tools/lib/subcmd/subcmd-config.h b/tools/lib/subcmd/subcmd-config.h
index cc85140..9024dc1 100644
--- a/tools/lib/subcmd/subcmd-config.h
+++ b/tools/lib/subcmd/subcmd-config.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __PERF_SUBCMD_CONFIG_H
 #define __PERF_SUBCMD_CONFIG_H
 
diff --git a/tools/lib/subcmd/subcmd-util.h b/tools/lib/subcmd/subcmd-util.h
index 8fa5f03..794a375 100644
--- a/tools/lib/subcmd/subcmd-util.h
+++ b/tools/lib/subcmd/subcmd-util.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __SUBCMD_UTIL_H
 #define __SUBCMD_UTIL_H
 
diff --git a/tools/lib/symbol/kallsyms.c b/tools/lib/symbol/kallsyms.c
index d270ac0..914cb8e 100644
--- a/tools/lib/symbol/kallsyms.c
+++ b/tools/lib/symbol/kallsyms.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <ctype.h>
 #include "symbol/kallsyms.h"
 #include <stdio.h>
diff --git a/tools/lib/symbol/kallsyms.h b/tools/lib/symbol/kallsyms.h
index 4071316..bc40101 100644
--- a/tools/lib/symbol/kallsyms.h
+++ b/tools/lib/symbol/kallsyms.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __TOOLS_KALLSYMS_H_
 #define __TOOLS_KALLSYMS_H_ 1
 
diff --git a/tools/lib/traceevent/Makefile b/tools/lib/traceevent/Makefile
index 9b8555e..46cd5f8 100644
--- a/tools/lib/traceevent/Makefile
+++ b/tools/lib/traceevent/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 # trace-cmd version
 EP_VERSION = 1
 EP_PATCHLEVEL = 1
diff --git a/tools/lib/traceevent/plugin_cfg80211.c b/tools/lib/traceevent/plugin_cfg80211.c
index ec57d0c..8f85869 100644
--- a/tools/lib/traceevent/plugin_cfg80211.c
+++ b/tools/lib/traceevent/plugin_cfg80211.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 #include <string.h>
 #include <inttypes.h>
diff --git a/tools/lib/traceevent/plugin_scsi.c b/tools/lib/traceevent/plugin_scsi.c
index 3727de4..5e750af 100644
--- a/tools/lib/traceevent/plugin_scsi.c
+++ b/tools/lib/traceevent/plugin_scsi.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 #include <string.h>
 #include <inttypes.h>
diff --git a/tools/lib/traceevent/plugin_xen.c b/tools/lib/traceevent/plugin_xen.c
index 3a413ea..690173b 100644
--- a/tools/lib/traceevent/plugin_xen.c
+++ b/tools/lib/traceevent/plugin_xen.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/tools/lib/vsprintf.c b/tools/lib/vsprintf.c
index 45f9a06..e08ee14 100644
--- a/tools/lib/vsprintf.c
+++ b/tools/lib/vsprintf.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <sys/types.h>
 #include <linux/kernel.h>
 #include <stdio.h>