cregit-Linux how code gets into the kernel

Release 4.12 include/linux/tracehook.h

Directory: include/linux
 * 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.



#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/security.h>
#include <linux/task_work.h>
#include <linux/memcontrol.h>
struct linux_binprm;

 * ptrace report for syscall entry and exit looks identical.

static inline int ptrace_report_syscall(struct pt_regs *regs) { int ptrace = current->ptrace; if (!(ptrace & PT_PTRACED)) return 0; 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; } return fatal_signal_pending(current); }


Roland McGrath6885.00%133.33%
Oleg Nesterov1012.50%133.33%
Tejun Heo22.50%133.33%

/** * 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) { return ptrace_report_syscall(regs); }


Roland McGrath1894.74%150.00%
Oleg Nesterov15.26%150.00%

/** * 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); }


Oleg Nesterov3060.00%150.00%
Roland McGrath2040.00%150.00%

/** * 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); }


Roland McGrath19100.00%1100.00%

/** * 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 }


Roland McGrath2784.38%150.00%
Oleg Nesterov515.62%150.00%

/** * 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) { /* * The caller just cleared 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(); mem_cgroup_handle_over_high(); }


Oleg Nesterov1548.39%120.00%
Roland McGrath1032.26%120.00%
Tejun Heo39.68%120.00%
Al Viro26.45%120.00%
Peter Zijlstra13.23%120.00%

#endif /* <linux/tracehook.h> */

Overall Contributors

Roland McGrath19071.43%746.67%
Oleg Nesterov6424.06%320.00%
Tejun Heo83.01%213.33%
Al Viro20.75%16.67%
Richard Weinberger10.38%16.67%
Peter Zijlstra10.38%16.67%
Directory: include/linux
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with cregit.