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>
2017-11-01 08:07:57 -06:00
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# SPDX-License-Identifier: GPL-2.0
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2005-04-16 16:20:36 -06:00
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#
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# Makefile for the linux kernel.
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#
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2012-12-10 21:58:43 -07:00
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obj-y += firmware.o
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2005-04-16 16:20:36 -06:00
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obj-$(CONFIG_SA1111) += sa1111.o
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obj-$(CONFIG_DMABOUNCE) += dmabounce.o
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2018-08-14 06:12:20 -06:00
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obj-$(CONFIG_KRAIT_L2_ACCESSORS) += krait-l2-accessors.o
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2005-04-16 16:20:36 -06:00
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obj-$(CONFIG_SHARP_LOCOMO) += locomo.o
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obj-$(CONFIG_SHARP_PARAM) += sharpsl_param.o
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obj-$(CONFIG_SHARP_SCOOP) += scoop.o
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2018-06-06 03:25:16 -06:00
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obj-$(CONFIG_CPU_V7) += secure_cntvoff.o
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2007-09-23 08:59:52 -06:00
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obj-$(CONFIG_PCI_HOST_ITE8152) += it8152.o
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2012-11-19 14:02:17 -07:00
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obj-$(CONFIG_MCPM) += mcpm_head.o mcpm_entry.o mcpm_platsmp.o vlock.o
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2014-02-14 04:46:02 -07:00
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CFLAGS_REMOVE_mcpm_entry.o = -pg
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2013-05-02 04:38:10 -06:00
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AFLAGS_mcpm_head.o := -march=armv7-a
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AFLAGS_vlock.o := -march=armv7-a
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ARM: b.L: core switcher code
This is the core code implementing big.LITTLE switcher functionality.
Rationale for this code is available here:
http://lwn.net/Articles/481055/
The main entry point for a switch request is:
void bL_switch_request(unsigned int cpu, unsigned int new_cluster_id)
If the calling CPU is not the wanted one, this wrapper takes care of
sending the request to the appropriate CPU with schedule_work_on().
At the moment the core switch operation is handled by bL_switch_to()
which must be called on the CPU for which a switch is requested.
What this code does:
* Return early if the current cluster is the wanted one.
* Close the gate in the kernel entry vector for both the inbound
and outbound CPUs.
* Wake up the inbound CPU so it can perform its reset sequence in
parallel up to the kernel entry vector gate.
* Migrate all interrupts in the GIC targeting the outbound CPU
interface to the inbound CPU interface, including SGIs. This is
performed by gic_migrate_target() in drivers/irqchip/irq-gic.c.
* Call cpu_pm_enter() which takes care of flushing the VFP state to
RAM and save the CPU interface config from the GIC to RAM.
* Modify the cpu_logical_map to refer to the inbound physical CPU.
* Call cpu_suspend() which saves the CPU state (general purpose
registers, page table address) onto the stack and store the
resulting stack pointer in an array indexed by the updated
cpu_logical_map, then call the provided shutdown function.
This happens in arch/arm/kernel/sleep.S.
At this point, the provided shutdown function executed by the outbound
CPU ungates the inbound CPU. Therefore the inbound CPU:
* Picks up the saved stack pointer in the array indexed by its MPIDR
in arch/arm/kernel/sleep.S.
* The MMU and caches are re-enabled using the saved state on the
provided stack, just like if this was a resume operation from a
suspended state.
* Then cpu_suspend() returns, although this is on the inbound CPU
rather than the outbound CPU which called it initially.
* The function cpu_pm_exit() is called which effect is to restore the
CPU interface state in the GIC using the state previously saved by
the outbound CPU.
* Exit of bL_switch_to() to resume normal kernel execution on the
new CPU.
However, the outbound CPU is potentially still running in parallel while
the inbound CPU is resuming normal kernel execution, hence we need
per CPU stack isolation to execute bL_do_switch(). After the outbound
CPU has ungated the inbound CPU, it calls mcpm_cpu_power_down() to:
* Clean its L1 cache.
* If it is the last CPU still alive in its cluster (last man standing),
it also cleans its L2 cache and disables cache snooping from the other
cluster.
* Power down the CPU (or whole cluster).
Code called from bL_do_switch() might end up referencing 'current' for
some reasons. However, 'current' is derived from the stack pointer.
With any arbitrary stack, the returned value for 'current' and any
dereferenced values through it are just random garbage which may lead to
segmentation faults.
The active page table during the execution of bL_do_switch() is also a
problem. There is no guarantee that the inbound CPU won't destroy the
corresponding task which would free the attached page table while the
outbound CPU is still running and relying on it.
To solve both issues, we borrow some of the task space belonging to
the init/idle task which, by its nature, is lightly used and therefore
is unlikely to clash with our usage. The init task is also never going
away.
Right now the logical CPU number is assumed to be equivalent to the
physical CPU number within each cluster. The kernel should also be
booted with only one cluster active. These limitations will be lifted
eventually.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
2012-04-12 00:56:10 -06:00
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obj-$(CONFIG_BL_SWITCHER) += bL_switcher.o
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2012-04-12 01:04:28 -06:00
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obj-$(CONFIG_BL_SWITCHER_DUMMY_IF) += bL_switcher_dummy_if.o
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