linux/arch/mips/kernel/uprobes.c

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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 14:07:57 +00:00
// SPDX-License-Identifier: GPL-2.0
#include <linux/highmem.h>
#include <linux/kdebug.h>
#include <linux/types.h>
#include <linux/notifier.h>
#include <linux/sched.h>
#include <linux/uprobes.h>
#include <asm/branch.h>
#include <asm/cpu-features.h>
#include <asm/ptrace.h>
#include "probes-common.h"
static inline int insn_has_delay_slot(const union mips_instruction insn)
{
return __insn_has_delay_slot(insn);
}
/**
* arch_uprobe_analyze_insn - instruction analysis including validity and fixups.
* @mm: the probed address space.
* @arch_uprobe: the probepoint information.
* @addr: virtual address at which to install the probepoint
* Return 0 on success or a -ve number on error.
*/
int arch_uprobe_analyze_insn(struct arch_uprobe *aup,
struct mm_struct *mm, unsigned long addr)
{
union mips_instruction inst;
/*
* For the time being this also blocks attempts to use uprobes with
* MIPS16 and microMIPS.
*/
if (addr & 0x03)
return -EINVAL;
inst.word = aup->insn[0];
if (__insn_is_compact_branch(inst)) {
pr_notice("Uprobes for compact branches are not supported\n");
return -EINVAL;
}
aup->ixol[0] = aup->insn[insn_has_delay_slot(inst)];
aup->ixol[1] = UPROBE_BRK_UPROBE_XOL; /* NOP */
return 0;
}
/**
* is_trap_insn - check if the instruction is a trap variant
* @insn: instruction to be checked.
* Returns true if @insn is a trap variant.
*
* This definition overrides the weak definition in kernel/events/uprobes.c.
* and is needed for the case where an architecture has multiple trap
* instructions (like PowerPC or MIPS). We treat BREAK just like the more
* modern conditional trap instructions.
*/
bool is_trap_insn(uprobe_opcode_t *insn)
{
union mips_instruction inst;
inst.word = *insn;
switch (inst.i_format.opcode) {
case spec_op:
switch (inst.r_format.func) {
case break_op:
case teq_op:
case tge_op:
case tgeu_op:
case tlt_op:
case tltu_op:
case tne_op:
return true;
}
break;
case bcond_op: /* Yes, really ... */
switch (inst.u_format.rt) {
case teqi_op:
case tgei_op:
case tgeiu_op:
case tlti_op:
case tltiu_op:
case tnei_op:
return true;
}
break;
}
return false;
}
#define UPROBE_TRAP_NR ULONG_MAX
/*
* arch_uprobe_pre_xol - prepare to execute out of line.
* @auprobe: the probepoint information.
* @regs: reflects the saved user state of current task.
*/
int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
/*
* Now find the EPC where to resume after the breakpoint has been
* dealt with. This may require emulation of a branch.
*/
aup->resume_epc = regs->cp0_epc + 4;
if (insn_has_delay_slot((union mips_instruction) aup->insn[0])) {
__compute_return_epc_for_insn(regs,
(union mips_instruction) aup->insn[0]);
aup->resume_epc = regs->cp0_epc;
}
utask->autask.saved_trap_nr = current->thread.trap_nr;
current->thread.trap_nr = UPROBE_TRAP_NR;
regs->cp0_epc = current->utask->xol_vaddr;
return 0;
}
int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
current->thread.trap_nr = utask->autask.saved_trap_nr;
regs->cp0_epc = aup->resume_epc;
return 0;
}
/*
* If xol insn itself traps and generates a signal(Say,
* SIGILL/SIGSEGV/etc), then detect the case where a singlestepped
* instruction jumps back to its own address. It is assumed that anything
* like do_page_fault/do_trap/etc sets thread.trap_nr != -1.
*
* arch_uprobe_pre_xol/arch_uprobe_post_xol save/restore thread.trap_nr,
* arch_uprobe_xol_was_trapped() simply checks that ->trap_nr is not equal to
* UPROBE_TRAP_NR == -1 set by arch_uprobe_pre_xol().
*/
bool arch_uprobe_xol_was_trapped(struct task_struct *tsk)
{
if (tsk->thread.trap_nr != UPROBE_TRAP_NR)
return true;
return false;
}
int arch_uprobe_exception_notify(struct notifier_block *self,
unsigned long val, void *data)
{
struct die_args *args = data;
struct pt_regs *regs = args->regs;
/* regs == NULL is a kernel bug */
if (WARN_ON(!regs))
return NOTIFY_DONE;
/* We are only interested in userspace traps */
if (!user_mode(regs))
return NOTIFY_DONE;
switch (val) {
case DIE_UPROBE:
if (uprobe_pre_sstep_notifier(regs))
return NOTIFY_STOP;
break;
case DIE_UPROBE_XOL:
if (uprobe_post_sstep_notifier(regs))
return NOTIFY_STOP;
break;
default:
break;
}
return 0;
}
/*
* This function gets called when XOL instruction either gets trapped or
* the thread has a fatal signal. Reset the instruction pointer to its
* probed address for the potential restart or for post mortem analysis.
*/
void arch_uprobe_abort_xol(struct arch_uprobe *aup,
struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
current->thread.trap_nr = utask->autask.saved_trap_nr;
instruction_pointer_set(regs, utask->vaddr);
}
unsigned long arch_uretprobe_hijack_return_addr(
unsigned long trampoline_vaddr, struct pt_regs *regs)
{
unsigned long ra;
ra = regs->regs[31];
/* Replace the return address with the trampoline address */
regs->regs[31] = trampoline_vaddr;
return ra;
}
void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
void *src, unsigned long len)
{
unsigned long kaddr, kstart;
/* Initialize the slot */
kaddr = (unsigned long)kmap_atomic(page);
kstart = kaddr + (vaddr & ~PAGE_MASK);
memcpy((void *)kstart, src, len);
flush_icache_range(kstart, kstart + len);
kunmap_atomic((void *)kaddr);
}
/**
* uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
* @regs: Reflects the saved state of the task after it has hit a breakpoint
* instruction.
* Return the address of the breakpoint instruction.
*
* This overrides the weak version in kernel/events/uprobes.c.
*/
unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
{
return instruction_pointer(regs);
}
/*
* See if the instruction can be emulated.
* Returns true if instruction was emulated, false otherwise.
*
* For now we always emulate so this function just returns false.
*/
bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
return false;
}