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-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Tracing hooks
- *
- * Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
- *
- * This file defines hook entry points called by core code where
- * user tracing/debugging support might need to do something. These
- * entry points are called tracehook_*(). Each hook declared below
- * has a detailed kerneldoc comment giving the context (locking et
- * al) from which it is called, and the meaning of its return value.
- *
- * Each function here typically has only one call site, so it is ok
- * to have some nontrivial tracehook_*() inlines. In all cases, the
- * fast path when no tracing is enabled should be very short.
- *
- * The purpose of this file and the tracehook_* layer is to consolidate
- * the interface that the kernel core and arch code uses to enable any
- * user debugging or tracing facility (such as ptrace). The interfaces
- * here are carefully documented so that maintainers of core and arch
- * code do not need to think about the implementation details of the
- * tracing facilities. Likewise, maintainers of the tracing code do not
- * need to understand all the calling core or arch code in detail, just
- * documented circumstances of each call, such as locking conditions.
- *
- * If the calling core code changes so that locking is different, then
- * it is ok to change the interface documented here. The maintainer of
- * core code changing should notify the maintainers of the tracing code
- * that they need to work out the change.
- *
- * Some tracehook_*() inlines take arguments that the current tracing
- * implementations might not necessarily use. These function signatures
- * are chosen to pass in all the information that is on hand in the
- * caller and might conceivably be relevant to a tracer, so that the
- * core code won't have to be updated when tracing adds more features.
- * If a call site changes so that some of those parameters are no longer
- * already on hand without extra work, then the tracehook_* interface
- * can change so there is no make-work burden on the core code. The
- * maintainer of core code changing should notify the maintainers of the
- * tracing code that they need to work out the change.
- */
-
-#ifndef _LINUX_TRACEHOOK_H
-#define _LINUX_TRACEHOOK_H 1
-
-#include <linux/sched.h>
-#include <linux/ptrace.h>
-#include <linux/security.h>
-#include <linux/task_work.h>
-#include <linux/memcontrol.h>
-#include <linux/blk-cgroup.h>
-struct linux_binprm;
-
-/*
- * ptrace report for syscall entry and exit looks identical.
- */
-static inline int ptrace_report_syscall(struct pt_regs *regs,
- unsigned long message)
-{
- int ptrace = current->ptrace;
-
- if (!(ptrace & PT_PTRACED))
- return 0;
-
- current->ptrace_message = message;
- ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
-
- /*
- * this isn't the same as continuing with a signal, but it will do
- * for normal use. strace only continues with a signal if the
- * stopping signal is not SIGTRAP. -brl
- */
- if (current->exit_code) {
- send_sig(current->exit_code, current, 1);
- current->exit_code = 0;
- }
-
- current->ptrace_message = 0;
- return fatal_signal_pending(current);
-}
-
-/**
- * tracehook_report_syscall_entry - task is about to attempt a system call
- * @regs: user register state of current task
- *
- * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or
- * %SYSCALL_WORK_SYSCALL_EMU have been set, when the current task has just
- * entered the kernel for a system call. Full user register state is
- * available here. Changing the values in @regs can affect the system
- * call number and arguments to be tried. It is safe to block here,
- * preventing the system call from beginning.
- *
- * Returns zero normally, or nonzero if the calling arch code should abort
- * the system call. That must prevent normal entry so no system call is
- * made. If @task ever returns to user mode after this, its register state
- * is unspecified, but should be something harmless like an %ENOSYS error
- * return. It should preserve enough information so that syscall_rollback()
- * can work (see asm-generic/syscall.h).
- *
- * Called without locks, just after entering kernel mode.
- */
-static inline __must_check int tracehook_report_syscall_entry(
- struct pt_regs *regs)
-{
- return ptrace_report_syscall(regs, PTRACE_EVENTMSG_SYSCALL_ENTRY);
-}
-
-/**
- * tracehook_report_syscall_exit - task has just finished a system call
- * @regs: user register state of current task
- * @step: nonzero if simulating single-step or block-step
- *
- * This will be called if %SYSCALL_WORK_SYSCALL_TRACE has been set, when
- * the current task has just finished an attempted system call. Full
- * user register state is available here. It is safe to block here,
- * preventing signals from being processed.
- *
- * If @step is nonzero, this report is also in lieu of the normal
- * trap that would follow the system call instruction because
- * user_enable_block_step() or user_enable_single_step() was used.
- * In this case, %SYSCALL_WORK_SYSCALL_TRACE might not be set.
- *
- * Called without locks, just before checking for pending signals.
- */
-static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)
-{
- if (step)
- user_single_step_report(regs);
- else
- ptrace_report_syscall(regs, PTRACE_EVENTMSG_SYSCALL_EXIT);
-}
-
-/**
- * tracehook_signal_handler - signal handler setup is complete
- * @stepping: nonzero if debugger single-step or block-step in use
- *
- * Called by the arch code after a signal handler has been set up.
- * Register and stack state reflects the user handler about to run.
- * Signal mask changes have already been made.
- *
- * Called without locks, shortly before returning to user mode
- * (or handling more signals).
- */
-static inline void tracehook_signal_handler(int stepping)
-{
- if (stepping)
- ptrace_notify(SIGTRAP);
-}
-
-/**
- * set_notify_resume - cause tracehook_notify_resume() to be called
- * @task: task that will call tracehook_notify_resume()
- *
- * Calling this arranges that @task will call tracehook_notify_resume()
- * before returning to user mode. If it's already running in user mode,
- * it will enter the kernel and call tracehook_notify_resume() soon.
- * If it's blocked, it will not be woken.
- */
-static inline void set_notify_resume(struct task_struct *task)
-{
-#ifdef TIF_NOTIFY_RESUME
- if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME))
- kick_process(task);
-#endif
-}
-
-/**
- * tracehook_notify_resume - report when about to return to user mode
- * @regs: user-mode registers of @current task
- *
- * This is called when %TIF_NOTIFY_RESUME has been set. Now we are
- * about to return to user mode, and the user state in @regs can be
- * inspected or adjusted. The caller in arch code has cleared
- * %TIF_NOTIFY_RESUME before the call. If the flag gets set again
- * asynchronously, this will be called again before we return to
- * user mode.
- *
- * Called without locks.
- */
-static inline void tracehook_notify_resume(struct pt_regs *regs)
-{
- clear_thread_flag(TIF_NOTIFY_RESUME);
- /*
- * This barrier pairs with task_work_add()->set_notify_resume() after
- * hlist_add_head(task->task_works);
- */
- smp_mb__after_atomic();
- if (unlikely(current->task_works))
- task_work_run();
-
-#ifdef CONFIG_KEYS_REQUEST_CACHE
- if (unlikely(current->cached_requested_key)) {
- key_put(current->cached_requested_key);
- current->cached_requested_key = NULL;
- }
-#endif
-
- mem_cgroup_handle_over_high();
- blkcg_maybe_throttle_current();
-
- rseq_handle_notify_resume(NULL, regs);
-}
-
-/*
- * called by exit_to_user_mode_loop() if ti_work & _TIF_NOTIFY_SIGNAL. This
- * is currently used by TWA_SIGNAL based task_work, which requires breaking
- * wait loops to ensure that task_work is noticed and run.
- */
-static inline void tracehook_notify_signal(void)
-{
- clear_thread_flag(TIF_NOTIFY_SIGNAL);
- smp_mb__after_atomic();
- if (current->task_works)
- task_work_run();
-}
-
-/*
- * Called when we have work to process from exit_to_user_mode_loop()
- */
-static inline void set_notify_signal(struct task_struct *task)
-{
- if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
- !wake_up_state(task, TASK_INTERRUPTIBLE))
- kick_process(task);
-}
-
-#endif /* <linux/tracehook.h> */