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1 | /* |
2 | * Access to user system call parameters and results |
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 is a stub providing documentation for what functions |
11 | * asm-ARCH/syscall.h files need to define. Most arch definitions |
12 | * will be simple inlines. |
13 | * |
14 | * All of these functions expect to be called with no locks, |
15 | * and only when the caller is sure that the task of interest |
16 | * cannot return to user mode while we are looking at it. |
17 | */ |
18 | |
19 | #ifndef _ASM_SYSCALL_H |
20 | #define _ASM_SYSCALL_H 1 |
21 | |
22 | struct task_struct; |
23 | struct pt_regs; |
24 | |
25 | /** |
26 | * syscall_get_nr - find what system call a task is executing |
27 | * @task: task of interest, must be blocked |
28 | * @regs: task_pt_regs() of @task |
29 | * |
30 | * If @task is executing a system call or is at system call |
31 | * tracing about to attempt one, returns the system call number. |
32 | * If @task is not executing a system call, i.e. it's blocked |
33 | * inside the kernel for a fault or signal, returns -1. |
34 | * |
35 | * Note this returns int even on 64-bit machines. Only 32 bits of |
36 | * system call number can be meaningful. If the actual arch value |
37 | * is 64 bits, this truncates to 32 bits so 0xffffffff means -1. |
38 | * |
39 | * It's only valid to call this when @task is known to be blocked. |
40 | */ |
41 | int syscall_get_nr(struct task_struct *task, struct pt_regs *regs); |
42 | |
43 | /** |
44 | * syscall_rollback - roll back registers after an aborted system call |
45 | * @task: task of interest, must be in system call exit tracing |
46 | * @regs: task_pt_regs() of @task |
47 | * |
48 | * It's only valid to call this when @task is stopped for system |
49 | * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT), |
50 | * after tracehook_report_syscall_entry() returned nonzero to prevent |
51 | * the system call from taking place. |
52 | * |
53 | * This rolls back the register state in @regs so it's as if the |
54 | * system call instruction was a no-op. The registers containing |
55 | * the system call number and arguments are as they were before the |
56 | * system call instruction. This may not be the same as what the |
57 | * register state looked like at system call entry tracing. |
58 | */ |
59 | void syscall_rollback(struct task_struct *task, struct pt_regs *regs); |
60 | |
61 | /** |
62 | * syscall_get_error - check result of traced system call |
63 | * @task: task of interest, must be blocked |
64 | * @regs: task_pt_regs() of @task |
65 | * |
66 | * Returns 0 if the system call succeeded, or -ERRORCODE if it failed. |
67 | * |
68 | * It's only valid to call this when @task is stopped for tracing on exit |
69 | * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
70 | */ |
71 | long syscall_get_error(struct task_struct *task, struct pt_regs *regs); |
72 | |
73 | /** |
74 | * syscall_get_return_value - get the return value of a traced system call |
75 | * @task: task of interest, must be blocked |
76 | * @regs: task_pt_regs() of @task |
77 | * |
78 | * Returns the return value of the successful system call. |
79 | * This value is meaningless if syscall_get_error() returned nonzero. |
80 | * |
81 | * It's only valid to call this when @task is stopped for tracing on exit |
82 | * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
83 | */ |
84 | long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs); |
85 | |
86 | /** |
87 | * syscall_set_return_value - change the return value of a traced system call |
88 | * @task: task of interest, must be blocked |
89 | * @regs: task_pt_regs() of @task |
90 | * @error: negative error code, or zero to indicate success |
91 | * @val: user return value if @error is zero |
92 | * |
93 | * This changes the results of the system call that user mode will see. |
94 | * If @error is zero, the user sees a successful system call with a |
95 | * return value of @val. If @error is nonzero, it's a negated errno |
96 | * code; the user sees a failed system call with this errno code. |
97 | * |
98 | * It's only valid to call this when @task is stopped for tracing on exit |
99 | * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
100 | */ |
101 | void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs, |
102 | int error, long val); |
103 | |
104 | /** |
105 | * syscall_get_arguments - extract system call parameter values |
106 | * @task: task of interest, must be blocked |
107 | * @regs: task_pt_regs() of @task |
108 | * @i: argument index [0,5] |
109 | * @n: number of arguments; n+i must be [1,6]. |
110 | * @args: array filled with argument values |
111 | * |
112 | * Fetches @n arguments to the system call starting with the @i'th argument |
113 | * (from 0 through 5). Argument @i is stored in @args[0], and so on. |
114 | * An arch inline version is probably optimal when @i and @n are constants. |
115 | * |
116 | * It's only valid to call this when @task is stopped for tracing on |
117 | * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
118 | * It's invalid to call this with @i + @n > 6; we only support system calls |
119 | * taking up to 6 arguments. |
120 | */ |
121 | void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, |
122 | unsigned int i, unsigned int n, unsigned long *args); |
123 | |
124 | /** |
125 | * syscall_set_arguments - change system call parameter value |
126 | * @task: task of interest, must be in system call entry tracing |
127 | * @regs: task_pt_regs() of @task |
128 | * @i: argument index [0,5] |
129 | * @n: number of arguments; n+i must be [1,6]. |
130 | * @args: array of argument values to store |
131 | * |
132 | * Changes @n arguments to the system call starting with the @i'th argument. |
133 | * Argument @i gets value @args[0], and so on. |
134 | * An arch inline version is probably optimal when @i and @n are constants. |
135 | * |
136 | * It's only valid to call this when @task is stopped for tracing on |
137 | * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. |
138 | * It's invalid to call this with @i + @n > 6; we only support system calls |
139 | * taking up to 6 arguments. |
140 | */ |
141 | void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs, |
142 | unsigned int i, unsigned int n, |
143 | const unsigned long *args); |
144 | |
145 | #endif /* _ASM_SYSCALL_H */ |
146 |
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