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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>
131 lines
5.8 KiB
C
131 lines
5.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __842_H__
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#define __842_H__
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/* The 842 compressed format is made up of multiple blocks, each of
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* which have the format:
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*
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* <template>[arg1][arg2][arg3][arg4]
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*
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* where there are between 0 and 4 template args, depending on the specific
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* template operation. For normal operations, each arg is either a specific
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* number of data bytes to add to the output buffer, or an index pointing
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* to a previously-written number of data bytes to copy to the output buffer.
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*
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* The template code is a 5-bit value. This code indicates what to do with
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* the following data. Template codes from 0 to 0x19 should use the template
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* table, the static "decomp_ops" table used in decompress. For each template
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* (table row), there are between 1 and 4 actions; each action corresponds to
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* an arg following the template code bits. Each action is either a "data"
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* type action, or a "index" type action, and each action results in 2, 4, or 8
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* bytes being written to the output buffer. Each template (i.e. all actions
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* in the table row) will add up to 8 bytes being written to the output buffer.
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* Any row with less than 4 actions is padded with noop actions, indicated by
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* N0 (for which there is no corresponding arg in the compressed data buffer).
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*
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* "Data" actions, indicated in the table by D2, D4, and D8, mean that the
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* corresponding arg is 2, 4, or 8 bytes, respectively, in the compressed data
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* buffer should be copied directly to the output buffer.
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*
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* "Index" actions, indicated in the table by I2, I4, and I8, mean the
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* corresponding arg is an index parameter that points to, respectively, a 2,
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* 4, or 8 byte value already in the output buffer, that should be copied to
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* the end of the output buffer. Essentially, the index points to a position
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* in a ring buffer that contains the last N bytes of output buffer data.
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* The number of bits for each index's arg are: 8 bits for I2, 9 bits for I4,
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* and 8 bits for I8. Since each index points to a 2, 4, or 8 byte section,
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* this means that I2 can reference 512 bytes ((2^8 bits = 256) * 2 bytes), I4
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* can reference 2048 bytes ((2^9 = 512) * 4 bytes), and I8 can reference 2048
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* bytes ((2^8 = 256) * 8 bytes). Think of it as a kind-of ring buffer for
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* each of I2, I4, and I8 that are updated for each byte written to the output
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* buffer. In this implementation, the output buffer is directly used for each
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* index; there is no additional memory required. Note that the index is into
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* a ring buffer, not a sliding window; for example, if there have been 260
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* bytes written to the output buffer, an I2 index of 0 would index to byte 256
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* in the output buffer, while an I2 index of 16 would index to byte 16 in the
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* output buffer.
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*
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* There are also 3 special template codes; 0x1b for "repeat", 0x1c for
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* "zeros", and 0x1e for "end". The "repeat" operation is followed by a 6 bit
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* arg N indicating how many times to repeat. The last 8 bytes written to the
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* output buffer are written again to the output buffer, N + 1 times. The
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* "zeros" operation, which has no arg bits, writes 8 zeros to the output
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* buffer. The "end" operation, which also has no arg bits, signals the end
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* of the compressed data. There may be some number of padding (don't care,
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* but usually 0) bits after the "end" operation bits, to fill the buffer
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* length to a specific byte multiple (usually a multiple of 8, 16, or 32
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* bytes).
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*
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* This software implementation also uses one of the undefined template values,
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* 0x1d as a special "short data" template code, to represent less than 8 bytes
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* of uncompressed data. It is followed by a 3 bit arg N indicating how many
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* data bytes will follow, and then N bytes of data, which should be copied to
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* the output buffer. This allows the software 842 compressor to accept input
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* buffers that are not an exact multiple of 8 bytes long. However, those
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* compressed buffers containing this sw-only template will be rejected by
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* the 842 hardware decompressor, and must be decompressed with this software
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* library. The 842 software compression module includes a parameter to
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* disable using this sw-only "short data" template, and instead simply
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* reject any input buffer that is not a multiple of 8 bytes long.
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*
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* After all actions for each operation code are processed, another template
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* code is in the next 5 bits. The decompression ends once the "end" template
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* code is detected.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/bitops.h>
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#include <linux/crc32.h>
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#include <asm/unaligned.h>
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#include <linux/sw842.h>
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/* special templates */
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#define OP_REPEAT (0x1B)
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#define OP_ZEROS (0x1C)
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#define OP_END (0x1E)
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/* sw only template - this is not in the hw design; it's used only by this
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* software compressor and decompressor, to allow input buffers that aren't
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* a multiple of 8.
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*/
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#define OP_SHORT_DATA (0x1D)
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/* additional bits of each op param */
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#define OP_BITS (5)
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#define REPEAT_BITS (6)
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#define SHORT_DATA_BITS (3)
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#define I2_BITS (8)
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#define I4_BITS (9)
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#define I8_BITS (8)
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#define CRC_BITS (32)
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#define REPEAT_BITS_MAX (0x3f)
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#define SHORT_DATA_BITS_MAX (0x7)
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/* Arbitrary values used to indicate action */
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#define OP_ACTION (0x70)
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#define OP_ACTION_INDEX (0x10)
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#define OP_ACTION_DATA (0x20)
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#define OP_ACTION_NOOP (0x40)
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#define OP_AMOUNT (0x0f)
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#define OP_AMOUNT_0 (0x00)
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#define OP_AMOUNT_2 (0x02)
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#define OP_AMOUNT_4 (0x04)
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#define OP_AMOUNT_8 (0x08)
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#define D2 (OP_ACTION_DATA | OP_AMOUNT_2)
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#define D4 (OP_ACTION_DATA | OP_AMOUNT_4)
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#define D8 (OP_ACTION_DATA | OP_AMOUNT_8)
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#define I2 (OP_ACTION_INDEX | OP_AMOUNT_2)
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#define I4 (OP_ACTION_INDEX | OP_AMOUNT_4)
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#define I8 (OP_ACTION_INDEX | OP_AMOUNT_8)
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#define N0 (OP_ACTION_NOOP | OP_AMOUNT_0)
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/* the max of the regular templates - not including the special templates */
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#define OPS_MAX (0x1a)
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#endif
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