| /* 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> */ |