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![Greg Kroah-Hartman](/assets/img/avatar_default.png)
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>
316 lines
8.6 KiB
C
316 lines
8.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* calibrate.c: default delay calibration
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*
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* Excised from init/main.c
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/jiffies.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/timex.h>
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#include <linux/smp.h>
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#include <linux/percpu.h>
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unsigned long lpj_fine;
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unsigned long preset_lpj;
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static int __init lpj_setup(char *str)
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{
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preset_lpj = simple_strtoul(str,NULL,0);
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return 1;
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}
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__setup("lpj=", lpj_setup);
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#ifdef ARCH_HAS_READ_CURRENT_TIMER
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/* This routine uses the read_current_timer() routine and gets the
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* loops per jiffy directly, instead of guessing it using delay().
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* Also, this code tries to handle non-maskable asynchronous events
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* (like SMIs)
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*/
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#define DELAY_CALIBRATION_TICKS ((HZ < 100) ? 1 : (HZ/100))
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#define MAX_DIRECT_CALIBRATION_RETRIES 5
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static unsigned long calibrate_delay_direct(void)
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{
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unsigned long pre_start, start, post_start;
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unsigned long pre_end, end, post_end;
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unsigned long start_jiffies;
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unsigned long timer_rate_min, timer_rate_max;
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unsigned long good_timer_sum = 0;
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unsigned long good_timer_count = 0;
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unsigned long measured_times[MAX_DIRECT_CALIBRATION_RETRIES];
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int max = -1; /* index of measured_times with max/min values or not set */
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int min = -1;
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int i;
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if (read_current_timer(&pre_start) < 0 )
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return 0;
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/*
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* A simple loop like
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* while ( jiffies < start_jiffies+1)
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* start = read_current_timer();
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* will not do. As we don't really know whether jiffy switch
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* happened first or timer_value was read first. And some asynchronous
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* event can happen between these two events introducing errors in lpj.
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*
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* So, we do
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* 1. pre_start <- When we are sure that jiffy switch hasn't happened
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* 2. check jiffy switch
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* 3. start <- timer value before or after jiffy switch
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* 4. post_start <- When we are sure that jiffy switch has happened
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*
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* Note, we don't know anything about order of 2 and 3.
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* Now, by looking at post_start and pre_start difference, we can
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* check whether any asynchronous event happened or not
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*/
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for (i = 0; i < MAX_DIRECT_CALIBRATION_RETRIES; i++) {
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pre_start = 0;
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read_current_timer(&start);
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start_jiffies = jiffies;
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while (time_before_eq(jiffies, start_jiffies + 1)) {
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pre_start = start;
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read_current_timer(&start);
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}
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read_current_timer(&post_start);
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pre_end = 0;
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end = post_start;
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while (time_before_eq(jiffies, start_jiffies + 1 +
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DELAY_CALIBRATION_TICKS)) {
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pre_end = end;
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read_current_timer(&end);
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}
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read_current_timer(&post_end);
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timer_rate_max = (post_end - pre_start) /
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DELAY_CALIBRATION_TICKS;
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timer_rate_min = (pre_end - post_start) /
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DELAY_CALIBRATION_TICKS;
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/*
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* If the upper limit and lower limit of the timer_rate is
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* >= 12.5% apart, redo calibration.
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*/
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if (start >= post_end)
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printk(KERN_NOTICE "calibrate_delay_direct() ignoring "
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"timer_rate as we had a TSC wrap around"
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" start=%lu >=post_end=%lu\n",
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start, post_end);
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if (start < post_end && pre_start != 0 && pre_end != 0 &&
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(timer_rate_max - timer_rate_min) < (timer_rate_max >> 3)) {
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good_timer_count++;
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good_timer_sum += timer_rate_max;
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measured_times[i] = timer_rate_max;
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if (max < 0 || timer_rate_max > measured_times[max])
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max = i;
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if (min < 0 || timer_rate_max < measured_times[min])
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min = i;
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} else
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measured_times[i] = 0;
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}
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/*
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* Find the maximum & minimum - if they differ too much throw out the
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* one with the largest difference from the mean and try again...
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*/
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while (good_timer_count > 1) {
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unsigned long estimate;
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unsigned long maxdiff;
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/* compute the estimate */
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estimate = (good_timer_sum/good_timer_count);
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maxdiff = estimate >> 3;
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/* if range is within 12% let's take it */
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if ((measured_times[max] - measured_times[min]) < maxdiff)
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return estimate;
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/* ok - drop the worse value and try again... */
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good_timer_sum = 0;
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good_timer_count = 0;
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if ((measured_times[max] - estimate) <
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(estimate - measured_times[min])) {
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printk(KERN_NOTICE "calibrate_delay_direct() dropping "
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"min bogoMips estimate %d = %lu\n",
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min, measured_times[min]);
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measured_times[min] = 0;
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min = max;
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} else {
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printk(KERN_NOTICE "calibrate_delay_direct() dropping "
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"max bogoMips estimate %d = %lu\n",
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max, measured_times[max]);
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measured_times[max] = 0;
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max = min;
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}
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for (i = 0; i < MAX_DIRECT_CALIBRATION_RETRIES; i++) {
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if (measured_times[i] == 0)
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continue;
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good_timer_count++;
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good_timer_sum += measured_times[i];
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if (measured_times[i] < measured_times[min])
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min = i;
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if (measured_times[i] > measured_times[max])
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max = i;
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}
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}
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printk(KERN_NOTICE "calibrate_delay_direct() failed to get a good "
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"estimate for loops_per_jiffy.\nProbably due to long platform "
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"interrupts. Consider using \"lpj=\" boot option.\n");
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return 0;
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}
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#else
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static unsigned long calibrate_delay_direct(void)
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{
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return 0;
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}
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#endif
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/*
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* This is the number of bits of precision for the loops_per_jiffy. Each
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* time we refine our estimate after the first takes 1.5/HZ seconds, so try
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* to start with a good estimate.
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* For the boot cpu we can skip the delay calibration and assign it a value
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* calculated based on the timer frequency.
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* For the rest of the CPUs we cannot assume that the timer frequency is same as
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* the cpu frequency, hence do the calibration for those.
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*/
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#define LPS_PREC 8
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static unsigned long calibrate_delay_converge(void)
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{
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/* First stage - slowly accelerate to find initial bounds */
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unsigned long lpj, lpj_base, ticks, loopadd, loopadd_base, chop_limit;
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int trials = 0, band = 0, trial_in_band = 0;
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lpj = (1<<12);
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/* wait for "start of" clock tick */
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ticks = jiffies;
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while (ticks == jiffies)
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; /* nothing */
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/* Go .. */
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ticks = jiffies;
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do {
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if (++trial_in_band == (1<<band)) {
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++band;
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trial_in_band = 0;
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}
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__delay(lpj * band);
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trials += band;
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} while (ticks == jiffies);
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/*
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* We overshot, so retreat to a clear underestimate. Then estimate
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* the largest likely undershoot. This defines our chop bounds.
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*/
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trials -= band;
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loopadd_base = lpj * band;
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lpj_base = lpj * trials;
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recalibrate:
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lpj = lpj_base;
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loopadd = loopadd_base;
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/*
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* Do a binary approximation to get lpj set to
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* equal one clock (up to LPS_PREC bits)
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*/
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chop_limit = lpj >> LPS_PREC;
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while (loopadd > chop_limit) {
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lpj += loopadd;
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ticks = jiffies;
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while (ticks == jiffies)
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; /* nothing */
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ticks = jiffies;
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__delay(lpj);
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if (jiffies != ticks) /* longer than 1 tick */
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lpj -= loopadd;
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loopadd >>= 1;
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}
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/*
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* If we incremented every single time possible, presume we've
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* massively underestimated initially, and retry with a higher
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* start, and larger range. (Only seen on x86_64, due to SMIs)
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*/
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if (lpj + loopadd * 2 == lpj_base + loopadd_base * 2) {
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lpj_base = lpj;
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loopadd_base <<= 2;
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goto recalibrate;
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}
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return lpj;
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}
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static DEFINE_PER_CPU(unsigned long, cpu_loops_per_jiffy) = { 0 };
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/*
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* Check if cpu calibration delay is already known. For example,
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* some processors with multi-core sockets may have all cores
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* with the same calibration delay.
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*
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* Architectures should override this function if a faster calibration
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* method is available.
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*/
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unsigned long __attribute__((weak)) calibrate_delay_is_known(void)
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{
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return 0;
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}
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/*
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* Indicate the cpu delay calibration is done. This can be used by
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* architectures to stop accepting delay timer registrations after this point.
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*/
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void __attribute__((weak)) calibration_delay_done(void)
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{
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}
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void calibrate_delay(void)
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{
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unsigned long lpj;
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static bool printed;
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int this_cpu = smp_processor_id();
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if (per_cpu(cpu_loops_per_jiffy, this_cpu)) {
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lpj = per_cpu(cpu_loops_per_jiffy, this_cpu);
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if (!printed)
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pr_info("Calibrating delay loop (skipped) "
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"already calibrated this CPU");
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} else if (preset_lpj) {
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lpj = preset_lpj;
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if (!printed)
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pr_info("Calibrating delay loop (skipped) "
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"preset value.. ");
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} else if ((!printed) && lpj_fine) {
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lpj = lpj_fine;
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pr_info("Calibrating delay loop (skipped), "
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"value calculated using timer frequency.. ");
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} else if ((lpj = calibrate_delay_is_known())) {
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;
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} else if ((lpj = calibrate_delay_direct()) != 0) {
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if (!printed)
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pr_info("Calibrating delay using timer "
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"specific routine.. ");
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} else {
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if (!printed)
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pr_info("Calibrating delay loop... ");
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lpj = calibrate_delay_converge();
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}
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per_cpu(cpu_loops_per_jiffy, this_cpu) = lpj;
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if (!printed)
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pr_cont("%lu.%02lu BogoMIPS (lpj=%lu)\n",
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lpj/(500000/HZ),
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(lpj/(5000/HZ)) % 100, lpj);
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loops_per_jiffy = lpj;
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printed = true;
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calibration_delay_done();
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}
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