![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>
383 lines
10 KiB
C
383 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2008 Matt Fleming <matt@console-pimps.org>
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* Copyright (C) 2008 Paul Mundt <lethal@linux-sh.org>
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*
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* Code for replacing ftrace calls with jumps.
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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*
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* Thanks goes to Ingo Molnar, for suggesting the idea.
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* Mathieu Desnoyers, for suggesting postponing the modifications.
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* Arjan van de Ven, for keeping me straight, and explaining to me
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* the dangers of modifying code on the run.
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*/
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <linux/string.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <asm/ftrace.h>
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#include <asm/cacheflush.h>
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#include <asm/unistd.h>
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#include <trace/syscall.h>
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#ifdef CONFIG_DYNAMIC_FTRACE
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static unsigned char ftrace_replaced_code[MCOUNT_INSN_SIZE];
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static unsigned char ftrace_nop[4];
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/*
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* If we're trying to nop out a call to a function, we instead
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* place a call to the address after the memory table.
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*
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* 8c011060 <a>:
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* 8c011060: 02 d1 mov.l 8c01106c <a+0xc>,r1
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* 8c011062: 22 4f sts.l pr,@-r15
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* 8c011064: 02 c7 mova 8c011070 <a+0x10>,r0
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* 8c011066: 2b 41 jmp @r1
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* 8c011068: 2a 40 lds r0,pr
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* 8c01106a: 09 00 nop
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* 8c01106c: 68 24 .word 0x2468 <--- ip
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* 8c01106e: 1d 8c .word 0x8c1d
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* 8c011070: 26 4f lds.l @r15+,pr <--- ip + MCOUNT_INSN_SIZE
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*
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* We write 0x8c011070 to 0x8c01106c so that on entry to a() we branch
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* past the _mcount call and continue executing code like normal.
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*/
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static unsigned char *ftrace_nop_replace(unsigned long ip)
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{
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__raw_writel(ip + MCOUNT_INSN_SIZE, ftrace_nop);
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return ftrace_nop;
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}
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static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
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{
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/* Place the address in the memory table. */
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__raw_writel(addr, ftrace_replaced_code);
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/*
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* No locking needed, this must be called via kstop_machine
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* which in essence is like running on a uniprocessor machine.
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*/
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return ftrace_replaced_code;
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}
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/*
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* Modifying code must take extra care. On an SMP machine, if
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* the code being modified is also being executed on another CPU
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* that CPU will have undefined results and possibly take a GPF.
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* We use kstop_machine to stop other CPUS from exectuing code.
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* But this does not stop NMIs from happening. We still need
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* to protect against that. We separate out the modification of
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* the code to take care of this.
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*
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* Two buffers are added: An IP buffer and a "code" buffer.
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*
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* 1) Put the instruction pointer into the IP buffer
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* and the new code into the "code" buffer.
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* 2) Wait for any running NMIs to finish and set a flag that says
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* we are modifying code, it is done in an atomic operation.
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* 3) Write the code
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* 4) clear the flag.
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* 5) Wait for any running NMIs to finish.
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*
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* If an NMI is executed, the first thing it does is to call
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* "ftrace_nmi_enter". This will check if the flag is set to write
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* and if it is, it will write what is in the IP and "code" buffers.
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*
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* The trick is, it does not matter if everyone is writing the same
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* content to the code location. Also, if a CPU is executing code
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* it is OK to write to that code location if the contents being written
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* are the same as what exists.
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*/
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#define MOD_CODE_WRITE_FLAG (1 << 31) /* set when NMI should do the write */
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static atomic_t nmi_running = ATOMIC_INIT(0);
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static int mod_code_status; /* holds return value of text write */
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static void *mod_code_ip; /* holds the IP to write to */
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static void *mod_code_newcode; /* holds the text to write to the IP */
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static void clear_mod_flag(void)
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{
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int old = atomic_read(&nmi_running);
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for (;;) {
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int new = old & ~MOD_CODE_WRITE_FLAG;
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if (old == new)
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break;
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old = atomic_cmpxchg(&nmi_running, old, new);
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}
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}
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static void ftrace_mod_code(void)
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{
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/*
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* Yes, more than one CPU process can be writing to mod_code_status.
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* (and the code itself)
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* But if one were to fail, then they all should, and if one were
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* to succeed, then they all should.
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*/
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mod_code_status = probe_kernel_write(mod_code_ip, mod_code_newcode,
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MCOUNT_INSN_SIZE);
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/* if we fail, then kill any new writers */
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if (mod_code_status)
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clear_mod_flag();
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}
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void arch_ftrace_nmi_enter(void)
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{
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if (atomic_inc_return(&nmi_running) & MOD_CODE_WRITE_FLAG) {
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smp_rmb();
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ftrace_mod_code();
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}
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/* Must have previous changes seen before executions */
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smp_mb();
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}
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void arch_ftrace_nmi_exit(void)
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{
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/* Finish all executions before clearing nmi_running */
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smp_mb();
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atomic_dec(&nmi_running);
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}
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static void wait_for_nmi_and_set_mod_flag(void)
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{
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if (!atomic_cmpxchg(&nmi_running, 0, MOD_CODE_WRITE_FLAG))
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return;
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do {
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cpu_relax();
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} while (atomic_cmpxchg(&nmi_running, 0, MOD_CODE_WRITE_FLAG));
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}
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static void wait_for_nmi(void)
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{
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if (!atomic_read(&nmi_running))
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return;
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do {
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cpu_relax();
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} while (atomic_read(&nmi_running));
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}
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static int
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do_ftrace_mod_code(unsigned long ip, void *new_code)
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{
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mod_code_ip = (void *)ip;
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mod_code_newcode = new_code;
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/* The buffers need to be visible before we let NMIs write them */
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smp_mb();
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wait_for_nmi_and_set_mod_flag();
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/* Make sure all running NMIs have finished before we write the code */
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smp_mb();
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ftrace_mod_code();
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/* Make sure the write happens before clearing the bit */
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smp_mb();
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clear_mod_flag();
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wait_for_nmi();
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return mod_code_status;
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}
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static int ftrace_modify_code(unsigned long ip, unsigned char *old_code,
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unsigned char *new_code)
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{
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unsigned char replaced[MCOUNT_INSN_SIZE];
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/*
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* Note:
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* We are paranoid about modifying text, as if a bug was to happen, it
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* could cause us to read or write to someplace that could cause harm.
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* Carefully read and modify the code with probe_kernel_*(), and make
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* sure what we read is what we expected it to be before modifying it.
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*/
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/* read the text we want to modify */
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if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* Make sure it is what we expect it to be */
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if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
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return -EINVAL;
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/* replace the text with the new text */
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if (do_ftrace_mod_code(ip, new_code))
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return -EPERM;
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flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);
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return 0;
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}
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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unsigned long ip = (unsigned long)(&ftrace_call) + MCOUNT_INSN_OFFSET;
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unsigned char old[MCOUNT_INSN_SIZE], *new;
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memcpy(old, (unsigned char *)ip, MCOUNT_INSN_SIZE);
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new = ftrace_call_replace(ip, (unsigned long)func);
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return ftrace_modify_code(ip, old, new);
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}
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int ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned char *new, *old;
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unsigned long ip = rec->ip;
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old = ftrace_call_replace(ip, addr);
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new = ftrace_nop_replace(ip);
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return ftrace_modify_code(rec->ip, old, new);
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}
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned char *new, *old;
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unsigned long ip = rec->ip;
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old = ftrace_nop_replace(ip);
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new = ftrace_call_replace(ip, addr);
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return ftrace_modify_code(rec->ip, old, new);
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}
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int __init ftrace_dyn_arch_init(void)
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{
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return 0;
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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#ifdef CONFIG_DYNAMIC_FTRACE
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extern void ftrace_graph_call(void);
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static int ftrace_mod(unsigned long ip, unsigned long old_addr,
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unsigned long new_addr)
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{
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unsigned char code[MCOUNT_INSN_SIZE];
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if (probe_kernel_read(code, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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if (old_addr != __raw_readl((unsigned long *)code))
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return -EINVAL;
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__raw_writel(new_addr, ip);
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return 0;
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}
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int ftrace_enable_ftrace_graph_caller(void)
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{
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unsigned long ip, old_addr, new_addr;
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ip = (unsigned long)(&ftrace_graph_call) + GRAPH_INSN_OFFSET;
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old_addr = (unsigned long)(&skip_trace);
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new_addr = (unsigned long)(&ftrace_graph_caller);
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return ftrace_mod(ip, old_addr, new_addr);
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}
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int ftrace_disable_ftrace_graph_caller(void)
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{
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unsigned long ip, old_addr, new_addr;
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ip = (unsigned long)(&ftrace_graph_call) + GRAPH_INSN_OFFSET;
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old_addr = (unsigned long)(&ftrace_graph_caller);
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new_addr = (unsigned long)(&skip_trace);
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return ftrace_mod(ip, old_addr, new_addr);
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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/*
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* Hook the return address and push it in the stack of return addrs
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* in the current thread info.
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*
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* This is the main routine for the function graph tracer. The function
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* graph tracer essentially works like this:
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*
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* parent is the stack address containing self_addr's return address.
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* We pull the real return address out of parent and store it in
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* current's ret_stack. Then, we replace the return address on the stack
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* with the address of return_to_handler. self_addr is the function that
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* called mcount.
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*
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* When self_addr returns, it will jump to return_to_handler which calls
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* ftrace_return_to_handler. ftrace_return_to_handler will pull the real
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* return address off of current's ret_stack and jump to it.
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*/
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void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
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{
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unsigned long old;
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int faulted, err;
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struct ftrace_graph_ent trace;
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unsigned long return_hooker = (unsigned long)&return_to_handler;
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if (unlikely(ftrace_graph_is_dead()))
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return;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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/*
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* Protect against fault, even if it shouldn't
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* happen. This tool is too much intrusive to
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* ignore such a protection.
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*/
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__asm__ __volatile__(
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"1: \n\t"
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"mov.l @%2, %0 \n\t"
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"2: \n\t"
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"mov.l %3, @%2 \n\t"
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"mov #0, %1 \n\t"
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"3: \n\t"
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".section .fixup, \"ax\" \n\t"
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"4: \n\t"
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"mov.l 5f, %0 \n\t"
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"jmp @%0 \n\t"
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" mov #1, %1 \n\t"
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".balign 4 \n\t"
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"5: .long 3b \n\t"
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".previous \n\t"
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".section __ex_table,\"a\" \n\t"
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".long 1b, 4b \n\t"
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".long 2b, 4b \n\t"
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".previous \n\t"
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: "=&r" (old), "=r" (faulted)
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: "r" (parent), "r" (return_hooker)
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);
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if (unlikely(faulted)) {
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ftrace_graph_stop();
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WARN_ON(1);
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return;
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}
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err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0, NULL);
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if (err == -EBUSY) {
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__raw_writel(old, parent);
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return;
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}
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trace.func = self_addr;
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/* Only trace if the calling function expects to */
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if (!ftrace_graph_entry(&trace)) {
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current->curr_ret_stack--;
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__raw_writel(old, parent);
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}
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}
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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