| Roland McGrath | 88ac292 | 2008-07-25 19:45:43 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Tracing hooks |
| 3 | * |
| 4 | * Copyright (C) 2008 Red Hat, Inc. All rights reserved. |
| 5 | * |
| 6 | * This copyrighted material is made available to anyone wishing to use, |
| 7 | * modify, copy, or redistribute it subject to the terms and conditions |
| 8 | * of the GNU General Public License v.2. |
| 9 | * |
| 10 | * This file defines hook entry points called by core code where |
| 11 | * user tracing/debugging support might need to do something. These |
| 12 | * entry points are called tracehook_*(). Each hook declared below |
| 13 | * has a detailed kerneldoc comment giving the context (locking et |
| 14 | * al) from which it is called, and the meaning of its return value. |
| 15 | * |
| 16 | * Each function here typically has only one call site, so it is ok |
| 17 | * to have some nontrivial tracehook_*() inlines. In all cases, the |
| 18 | * fast path when no tracing is enabled should be very short. |
| 19 | * |
| 20 | * The purpose of this file and the tracehook_* layer is to consolidate |
| 21 | * the interface that the kernel core and arch code uses to enable any |
| 22 | * user debugging or tracing facility (such as ptrace). The interfaces |
| 23 | * here are carefully documented so that maintainers of core and arch |
| 24 | * code do not need to think about the implementation details of the |
| 25 | * tracing facilities. Likewise, maintainers of the tracing code do not |
| 26 | * need to understand all the calling core or arch code in detail, just |
| 27 | * documented circumstances of each call, such as locking conditions. |
| 28 | * |
| 29 | * If the calling core code changes so that locking is different, then |
| 30 | * it is ok to change the interface documented here. The maintainer of |
| 31 | * core code changing should notify the maintainers of the tracing code |
| 32 | * that they need to work out the change. |
| 33 | * |
| 34 | * Some tracehook_*() inlines take arguments that the current tracing |
| 35 | * implementations might not necessarily use. These function signatures |
| 36 | * are chosen to pass in all the information that is on hand in the |
| 37 | * caller and might conceivably be relevant to a tracer, so that the |
| 38 | * core code won't have to be updated when tracing adds more features. |
| 39 | * If a call site changes so that some of those parameters are no longer |
| 40 | * already on hand without extra work, then the tracehook_* interface |
| 41 | * can change so there is no make-work burden on the core code. The |
| 42 | * maintainer of core code changing should notify the maintainers of the |
| 43 | * tracing code that they need to work out the change. |
| 44 | */ |
| 45 | |
| 46 | #ifndef _LINUX_TRACEHOOK_H |
| 47 | #define _LINUX_TRACEHOOK_H 1 |
| 48 | |
| 49 | #include <linux/sched.h> |
| 50 | #include <linux/ptrace.h> |
| 51 | |
| 52 | #endif /* <linux/tracehook.h> */ |