478 lines
12 KiB
C
478 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/context_tracking.h>
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#include <linux/entry-common.h>
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#include <linux/resume_user_mode.h>
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#include <linux/highmem.h>
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#include <linux/jump_label.h>
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#include <linux/livepatch.h>
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#include <linux/audit.h>
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#include <linux/tick.h>
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#include "common.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/syscalls.h>
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/* See comment for enter_from_user_mode() in entry-common.h */
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static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
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{
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arch_enter_from_user_mode(regs);
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lockdep_hardirqs_off(CALLER_ADDR0);
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CT_WARN_ON(ct_state() != CONTEXT_USER);
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user_exit_irqoff();
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instrumentation_begin();
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trace_hardirqs_off_finish();
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instrumentation_end();
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}
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void noinstr enter_from_user_mode(struct pt_regs *regs)
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{
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__enter_from_user_mode(regs);
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}
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static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
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{
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if (unlikely(audit_context())) {
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unsigned long args[6];
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syscall_get_arguments(current, regs, args);
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audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]);
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}
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}
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static long syscall_trace_enter(struct pt_regs *regs, long syscall,
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unsigned long work)
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{
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long ret = 0;
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/*
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* Handle Syscall User Dispatch. This must comes first, since
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* the ABI here can be something that doesn't make sense for
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* other syscall_work features.
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*/
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if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {
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if (syscall_user_dispatch(regs))
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return -1L;
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}
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/* Handle ptrace */
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if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {
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ret = ptrace_report_syscall_entry(regs);
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if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))
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return -1L;
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}
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/* Do seccomp after ptrace, to catch any tracer changes. */
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if (work & SYSCALL_WORK_SECCOMP) {
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ret = __secure_computing(NULL);
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if (ret == -1L)
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return ret;
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}
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/* Either of the above might have changed the syscall number */
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syscall = syscall_get_nr(current, regs);
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if (unlikely(work & SYSCALL_WORK_SYSCALL_TRACEPOINT))
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trace_sys_enter(regs, syscall);
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syscall_enter_audit(regs, syscall);
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return ret ? : syscall;
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}
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static __always_inline long
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__syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
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{
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unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
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if (work & SYSCALL_WORK_ENTER)
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syscall = syscall_trace_enter(regs, syscall, work);
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return syscall;
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}
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long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
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{
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return __syscall_enter_from_user_work(regs, syscall);
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}
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noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
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{
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long ret;
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__enter_from_user_mode(regs);
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instrumentation_begin();
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local_irq_enable();
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ret = __syscall_enter_from_user_work(regs, syscall);
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instrumentation_end();
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return ret;
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}
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noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs)
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{
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__enter_from_user_mode(regs);
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instrumentation_begin();
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local_irq_enable();
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instrumentation_end();
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}
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/* See comment for exit_to_user_mode() in entry-common.h */
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static __always_inline void __exit_to_user_mode(void)
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{
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instrumentation_begin();
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trace_hardirqs_on_prepare();
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lockdep_hardirqs_on_prepare();
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instrumentation_end();
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user_enter_irqoff();
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arch_exit_to_user_mode();
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lockdep_hardirqs_on(CALLER_ADDR0);
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}
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void noinstr exit_to_user_mode(void)
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{
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__exit_to_user_mode();
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}
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/* Workaround to allow gradual conversion of architecture code */
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void __weak arch_do_signal_or_restart(struct pt_regs *regs) { }
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static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
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unsigned long ti_work)
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{
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/*
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* Before returning to user space ensure that all pending work
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* items have been completed.
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*/
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while (ti_work & EXIT_TO_USER_MODE_WORK) {
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local_irq_enable_exit_to_user(ti_work);
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if (ti_work & _TIF_NEED_RESCHED)
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schedule();
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if (ti_work & _TIF_UPROBE)
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uprobe_notify_resume(regs);
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if (ti_work & _TIF_PATCH_PENDING)
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klp_update_patch_state(current);
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if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
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arch_do_signal_or_restart(regs);
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if (ti_work & _TIF_NOTIFY_RESUME)
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resume_user_mode_work(regs);
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/* Architecture specific TIF work */
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arch_exit_to_user_mode_work(regs, ti_work);
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/*
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* Disable interrupts and reevaluate the work flags as they
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* might have changed while interrupts and preemption was
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* enabled above.
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*/
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local_irq_disable_exit_to_user();
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/* Check if any of the above work has queued a deferred wakeup */
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tick_nohz_user_enter_prepare();
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ti_work = read_thread_flags();
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}
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/* Return the latest work state for arch_exit_to_user_mode() */
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return ti_work;
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}
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static void exit_to_user_mode_prepare(struct pt_regs *regs)
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{
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unsigned long ti_work = read_thread_flags();
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lockdep_assert_irqs_disabled();
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/* Flush pending rcuog wakeup before the last need_resched() check */
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tick_nohz_user_enter_prepare();
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if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK))
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ti_work = exit_to_user_mode_loop(regs, ti_work);
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arch_exit_to_user_mode_prepare(regs, ti_work);
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/* Ensure that the address limit is intact and no locks are held */
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addr_limit_user_check();
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kmap_assert_nomap();
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lockdep_assert_irqs_disabled();
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lockdep_sys_exit();
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}
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/*
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* If SYSCALL_EMU is set, then the only reason to report is when
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* SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall
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* instruction has been already reported in syscall_enter_from_user_mode().
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*/
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static inline bool report_single_step(unsigned long work)
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{
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if (work & SYSCALL_WORK_SYSCALL_EMU)
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return false;
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return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP;
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}
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static void syscall_exit_work(struct pt_regs *regs, unsigned long work)
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{
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bool step;
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/*
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* If the syscall was rolled back due to syscall user dispatching,
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* then the tracers below are not invoked for the same reason as
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* the entry side was not invoked in syscall_trace_enter(): The ABI
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* of these syscalls is unknown.
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*/
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if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {
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if (unlikely(current->syscall_dispatch.on_dispatch)) {
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current->syscall_dispatch.on_dispatch = false;
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return;
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}
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}
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audit_syscall_exit(regs);
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if (work & SYSCALL_WORK_SYSCALL_TRACEPOINT)
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trace_sys_exit(regs, syscall_get_return_value(current, regs));
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step = report_single_step(work);
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if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
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ptrace_report_syscall_exit(regs, step);
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}
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/*
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* Syscall specific exit to user mode preparation. Runs with interrupts
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* enabled.
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*/
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static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
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{
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unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
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unsigned long nr = syscall_get_nr(current, regs);
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CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
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if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
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if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr))
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local_irq_enable();
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}
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rseq_syscall(regs);
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/*
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* Do one-time syscall specific work. If these work items are
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* enabled, we want to run them exactly once per syscall exit with
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* interrupts enabled.
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*/
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if (unlikely(work & SYSCALL_WORK_EXIT))
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syscall_exit_work(regs, work);
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}
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static __always_inline void __syscall_exit_to_user_mode_work(struct pt_regs *regs)
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{
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syscall_exit_to_user_mode_prepare(regs);
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local_irq_disable_exit_to_user();
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exit_to_user_mode_prepare(regs);
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}
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void syscall_exit_to_user_mode_work(struct pt_regs *regs)
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{
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__syscall_exit_to_user_mode_work(regs);
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}
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__visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)
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{
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instrumentation_begin();
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__syscall_exit_to_user_mode_work(regs);
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instrumentation_end();
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__exit_to_user_mode();
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}
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noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs)
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{
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__enter_from_user_mode(regs);
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}
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noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
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{
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instrumentation_begin();
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exit_to_user_mode_prepare(regs);
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instrumentation_end();
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__exit_to_user_mode();
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}
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noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
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{
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irqentry_state_t ret = {
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.exit_rcu = false,
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};
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if (user_mode(regs)) {
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irqentry_enter_from_user_mode(regs);
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return ret;
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}
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/*
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* If this entry hit the idle task invoke ct_irq_enter() whether
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* RCU is watching or not.
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*
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* Interrupts can nest when the first interrupt invokes softirq
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* processing on return which enables interrupts.
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*
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* Scheduler ticks in the idle task can mark quiescent state and
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* terminate a grace period, if and only if the timer interrupt is
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* not nested into another interrupt.
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*
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* Checking for rcu_is_watching() here would prevent the nesting
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* interrupt to invoke ct_irq_enter(). If that nested interrupt is
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* the tick then rcu_flavor_sched_clock_irq() would wrongfully
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* assume that it is the first interrupt and eventually claim
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* quiescent state and end grace periods prematurely.
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*
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* Unconditionally invoke ct_irq_enter() so RCU state stays
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* consistent.
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*
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* TINY_RCU does not support EQS, so let the compiler eliminate
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* this part when enabled.
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*/
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if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) {
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/*
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* If RCU is not watching then the same careful
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* sequence vs. lockdep and tracing is required
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* as in irqentry_enter_from_user_mode().
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*/
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lockdep_hardirqs_off(CALLER_ADDR0);
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ct_irq_enter();
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instrumentation_begin();
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trace_hardirqs_off_finish();
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instrumentation_end();
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ret.exit_rcu = true;
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return ret;
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}
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/*
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* If RCU is watching then RCU only wants to check whether it needs
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* to restart the tick in NOHZ mode. rcu_irq_enter_check_tick()
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* already contains a warning when RCU is not watching, so no point
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* in having another one here.
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*/
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lockdep_hardirqs_off(CALLER_ADDR0);
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instrumentation_begin();
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rcu_irq_enter_check_tick();
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trace_hardirqs_off_finish();
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instrumentation_end();
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return ret;
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}
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void raw_irqentry_exit_cond_resched(void)
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{
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if (!preempt_count()) {
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/* Sanity check RCU and thread stack */
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rcu_irq_exit_check_preempt();
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if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
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WARN_ON_ONCE(!on_thread_stack());
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if (need_resched())
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preempt_schedule_irq();
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}
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}
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#ifdef CONFIG_PREEMPT_DYNAMIC
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#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
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DEFINE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
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#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
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DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
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void dynamic_irqentry_exit_cond_resched(void)
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{
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if (!static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
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return;
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raw_irqentry_exit_cond_resched();
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}
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#endif
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#endif
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noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
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{
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lockdep_assert_irqs_disabled();
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/* Check whether this returns to user mode */
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if (user_mode(regs)) {
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irqentry_exit_to_user_mode(regs);
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} else if (!regs_irqs_disabled(regs)) {
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/*
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* If RCU was not watching on entry this needs to be done
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* carefully and needs the same ordering of lockdep/tracing
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* and RCU as the return to user mode path.
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*/
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if (state.exit_rcu) {
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instrumentation_begin();
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/* Tell the tracer that IRET will enable interrupts */
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trace_hardirqs_on_prepare();
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lockdep_hardirqs_on_prepare();
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instrumentation_end();
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ct_irq_exit();
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lockdep_hardirqs_on(CALLER_ADDR0);
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return;
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}
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instrumentation_begin();
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if (IS_ENABLED(CONFIG_PREEMPTION))
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irqentry_exit_cond_resched();
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/* Covers both tracing and lockdep */
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trace_hardirqs_on();
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instrumentation_end();
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} else {
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/*
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* IRQ flags state is correct already. Just tell RCU if it
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* was not watching on entry.
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*/
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if (state.exit_rcu)
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ct_irq_exit();
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}
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}
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irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs)
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{
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irqentry_state_t irq_state;
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irq_state.lockdep = lockdep_hardirqs_enabled();
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__nmi_enter();
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lockdep_hardirqs_off(CALLER_ADDR0);
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lockdep_hardirq_enter();
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ct_nmi_enter();
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instrumentation_begin();
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trace_hardirqs_off_finish();
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ftrace_nmi_enter();
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instrumentation_end();
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return irq_state;
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}
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void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state)
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{
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instrumentation_begin();
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ftrace_nmi_exit();
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if (irq_state.lockdep) {
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trace_hardirqs_on_prepare();
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lockdep_hardirqs_on_prepare();
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}
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instrumentation_end();
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ct_nmi_exit();
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lockdep_hardirq_exit();
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if (irq_state.lockdep)
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lockdep_hardirqs_on(CALLER_ADDR0);
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__nmi_exit();
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}
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