Root/
1 | /* |
2 | * Tracing hooks |
3 | * |
4 | * Copyright (C) 2008-2009 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 | #include <linux/security.h> |
52 | #include <linux/task_work.h> |
53 | struct linux_binprm; |
54 | |
55 | /* |
56 | * ptrace report for syscall entry and exit looks identical. |
57 | */ |
58 | static inline int ptrace_report_syscall(struct pt_regs *regs) |
59 | { |
60 | int ptrace = current->ptrace; |
61 | |
62 | if (!(ptrace & PT_PTRACED)) |
63 | return 0; |
64 | |
65 | ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0)); |
66 | |
67 | /* |
68 | * this isn't the same as continuing with a signal, but it will do |
69 | * for normal use. strace only continues with a signal if the |
70 | * stopping signal is not SIGTRAP. -brl |
71 | */ |
72 | if (current->exit_code) { |
73 | send_sig(current->exit_code, current, 1); |
74 | current->exit_code = 0; |
75 | } |
76 | |
77 | return fatal_signal_pending(current); |
78 | } |
79 | |
80 | /** |
81 | * tracehook_report_syscall_entry - task is about to attempt a system call |
82 | * @regs: user register state of current task |
83 | * |
84 | * This will be called if %TIF_SYSCALL_TRACE has been set, when the |
85 | * current task has just entered the kernel for a system call. |
86 | * Full user register state is available here. Changing the values |
87 | * in @regs can affect the system call number and arguments to be tried. |
88 | * It is safe to block here, preventing the system call from beginning. |
89 | * |
90 | * Returns zero normally, or nonzero if the calling arch code should abort |
91 | * the system call. That must prevent normal entry so no system call is |
92 | * made. If @task ever returns to user mode after this, its register state |
93 | * is unspecified, but should be something harmless like an %ENOSYS error |
94 | * return. It should preserve enough information so that syscall_rollback() |
95 | * can work (see asm-generic/syscall.h). |
96 | * |
97 | * Called without locks, just after entering kernel mode. |
98 | */ |
99 | static inline __must_check int tracehook_report_syscall_entry( |
100 | struct pt_regs *regs) |
101 | { |
102 | return ptrace_report_syscall(regs); |
103 | } |
104 | |
105 | /** |
106 | * tracehook_report_syscall_exit - task has just finished a system call |
107 | * @regs: user register state of current task |
108 | * @step: nonzero if simulating single-step or block-step |
109 | * |
110 | * This will be called if %TIF_SYSCALL_TRACE has been set, when the |
111 | * current task has just finished an attempted system call. Full |
112 | * user register state is available here. It is safe to block here, |
113 | * preventing signals from being processed. |
114 | * |
115 | * If @step is nonzero, this report is also in lieu of the normal |
116 | * trap that would follow the system call instruction because |
117 | * user_enable_block_step() or user_enable_single_step() was used. |
118 | * In this case, %TIF_SYSCALL_TRACE might not be set. |
119 | * |
120 | * Called without locks, just before checking for pending signals. |
121 | */ |
122 | static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step) |
123 | { |
124 | if (step) { |
125 | siginfo_t info; |
126 | user_single_step_siginfo(current, regs, &info); |
127 | force_sig_info(SIGTRAP, &info, current); |
128 | return; |
129 | } |
130 | |
131 | ptrace_report_syscall(regs); |
132 | } |
133 | |
134 | /** |
135 | * tracehook_signal_handler - signal handler setup is complete |
136 | * @sig: number of signal being delivered |
137 | * @info: siginfo_t of signal being delivered |
138 | * @ka: sigaction setting that chose the handler |
139 | * @regs: user register state |
140 | * @stepping: nonzero if debugger single-step or block-step in use |
141 | * |
142 | * Called by the arch code after a signal handler has been set up. |
143 | * Register and stack state reflects the user handler about to run. |
144 | * Signal mask changes have already been made. |
145 | * |
146 | * Called without locks, shortly before returning to user mode |
147 | * (or handling more signals). |
148 | */ |
149 | static inline void tracehook_signal_handler(int sig, siginfo_t *info, |
150 | const struct k_sigaction *ka, |
151 | struct pt_regs *regs, int stepping) |
152 | { |
153 | if (stepping) |
154 | ptrace_notify(SIGTRAP); |
155 | } |
156 | |
157 | /** |
158 | * set_notify_resume - cause tracehook_notify_resume() to be called |
159 | * @task: task that will call tracehook_notify_resume() |
160 | * |
161 | * Calling this arranges that @task will call tracehook_notify_resume() |
162 | * before returning to user mode. If it's already running in user mode, |
163 | * it will enter the kernel and call tracehook_notify_resume() soon. |
164 | * If it's blocked, it will not be woken. |
165 | */ |
166 | static inline void set_notify_resume(struct task_struct *task) |
167 | { |
168 | #ifdef TIF_NOTIFY_RESUME |
169 | if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME)) |
170 | kick_process(task); |
171 | #endif |
172 | } |
173 | |
174 | /** |
175 | * tracehook_notify_resume - report when about to return to user mode |
176 | * @regs: user-mode registers of @current task |
177 | * |
178 | * This is called when %TIF_NOTIFY_RESUME has been set. Now we are |
179 | * about to return to user mode, and the user state in @regs can be |
180 | * inspected or adjusted. The caller in arch code has cleared |
181 | * %TIF_NOTIFY_RESUME before the call. If the flag gets set again |
182 | * asynchronously, this will be called again before we return to |
183 | * user mode. |
184 | * |
185 | * Called without locks. |
186 | */ |
187 | static inline void tracehook_notify_resume(struct pt_regs *regs) |
188 | { |
189 | /* |
190 | * The caller just cleared TIF_NOTIFY_RESUME. This barrier |
191 | * pairs with task_work_add()->set_notify_resume() after |
192 | * hlist_add_head(task->task_works); |
193 | */ |
194 | smp_mb__after_clear_bit(); |
195 | if (unlikely(current->task_works)) |
196 | task_work_run(); |
197 | } |
198 | |
199 | #endif /* <linux/tracehook.h> */ |
200 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9