| /* |
| * Tracing hooks |
| * |
| * Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved. |
| * |
| * This copyrighted material is made available to anyone wishing to use, |
| * modify, copy, or redistribute it subject to the terms and conditions |
| * of the GNU General Public License v.2. |
| * |
| * 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> |
| struct linux_binprm; |
| |
| /* |
| * ptrace report for syscall entry and exit looks identical. |
| */ |
| static inline void ptrace_report_syscall(struct pt_regs *regs) |
| { |
| int ptrace = current->ptrace; |
| |
| if (!(ptrace & PT_PTRACED)) |
| return; |
| |
| 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; |
| } |
| } |
| |
| /** |
| * tracehook_report_syscall_entry - task is about to attempt a system call |
| * @regs: user register state of current task |
| * |
| * This will be called if %TIF_SYSCALL_TRACE has 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) |
| { |
| ptrace_report_syscall(regs); |
| return 0; |
| } |
| |
| /** |
| * 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 %TIF_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, %TIF_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) { |
| siginfo_t info; |
| user_single_step_siginfo(current, regs, &info); |
| force_sig_info(SIGTRAP, &info, current); |
| return; |
| } |
| |
| ptrace_report_syscall(regs); |
| } |
| |
| /** |
| * tracehook_tracer_task - return the task that is tracing the given task |
| * @tsk: task to consider |
| * |
| * Returns NULL if no one is tracing @task, or the &struct task_struct |
| * pointer to its tracer. |
| * |
| * Must called under rcu_read_lock(). The pointer returned might be kept |
| * live only by RCU. During exec, this may be called with task_lock() |
| * held on @task, still held from when tracehook_unsafe_exec() was called. |
| */ |
| static inline struct task_struct *tracehook_tracer_task(struct task_struct *tsk) |
| { |
| if (tsk->ptrace & PT_PTRACED) |
| return rcu_dereference(tsk->parent); |
| return NULL; |
| } |
| |
| /** |
| * tracehook_signal_handler - signal handler setup is complete |
| * @sig: number of signal being delivered |
| * @info: siginfo_t of signal being delivered |
| * @ka: sigaction setting that chose the handler |
| * @regs: user register state |
| * @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 sig, siginfo_t *info, |
| const struct k_sigaction *ka, |
| struct pt_regs *regs, int stepping) |
| { |
| if (stepping) |
| ptrace_notify(SIGTRAP); |
| } |
| |
| #define DEATH_REAP -1 |
| #define DEATH_DELAYED_GROUP_LEADER -2 |
| |
| /** |
| * tracehook_notify_death - task is dead, ready to notify parent |
| * @task: @current task now exiting |
| * @death_cookie: value to pass to tracehook_report_death() |
| * @group_dead: nonzero if this was the last thread in the group to die |
| * |
| * A return value >= 0 means call do_notify_parent() with that signal |
| * number. Negative return value can be %DEATH_REAP to self-reap right |
| * now, or %DEATH_DELAYED_GROUP_LEADER to a zombie without notifying our |
| * parent. Note that a return value of 0 means a do_notify_parent() call |
| * that sends no signal, but still wakes up a parent blocked in wait*(). |
| * |
| * Called with write_lock_irq(&tasklist_lock) held. |
| */ |
| static inline int tracehook_notify_death(struct task_struct *task, |
| void **death_cookie, int group_dead) |
| { |
| if (task_detached(task)) |
| return task->ptrace ? SIGCHLD : DEATH_REAP; |
| |
| /* |
| * If something other than our normal parent is ptracing us, then |
| * send it a SIGCHLD instead of honoring exit_signal. exit_signal |
| * only has special meaning to our real parent. |
| */ |
| if (thread_group_empty(task) && !ptrace_reparented(task)) |
| return task->exit_signal; |
| |
| return task->ptrace ? SIGCHLD : DEATH_DELAYED_GROUP_LEADER; |
| } |
| |
| #ifdef TIF_NOTIFY_RESUME |
| /** |
| * 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) |
| { |
| if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME)) |
| kick_process(task); |
| } |
| |
| /** |
| * 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) |
| { |
| } |
| #endif /* TIF_NOTIFY_RESUME */ |
| |
| #endif /* <linux/tracehook.h> */ |