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828c365c RM |
1 | /* |
2 | * Access to user system call parameters and results | |
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 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 | * It's only valid to call this when @task is known to be blocked. | |
36 | */ | |
37 | long syscall_get_nr(struct task_struct *task, struct pt_regs *regs); | |
38 | ||
39 | /** | |
40 | * syscall_rollback - roll back registers after an aborted system call | |
41 | * @task: task of interest, must be in system call exit tracing | |
42 | * @regs: task_pt_regs() of @task | |
43 | * | |
44 | * It's only valid to call this when @task is stopped for system | |
45 | * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT), | |
46 | * after tracehook_report_syscall_entry() returned nonzero to prevent | |
47 | * the system call from taking place. | |
48 | * | |
49 | * This rolls back the register state in @regs so it's as if the | |
50 | * system call instruction was a no-op. The registers containing | |
51 | * the system call number and arguments are as they were before the | |
52 | * system call instruction. This may not be the same as what the | |
53 | * register state looked like at system call entry tracing. | |
54 | */ | |
55 | void syscall_rollback(struct task_struct *task, struct pt_regs *regs); | |
56 | ||
57 | /** | |
58 | * syscall_get_error - check result of traced system call | |
59 | * @task: task of interest, must be blocked | |
60 | * @regs: task_pt_regs() of @task | |
61 | * | |
62 | * Returns 0 if the system call succeeded, or -ERRORCODE if it failed. | |
63 | * | |
64 | * It's only valid to call this when @task is stopped for tracing on exit | |
65 | * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. | |
66 | */ | |
67 | long syscall_get_error(struct task_struct *task, struct pt_regs *regs); | |
68 | ||
69 | /** | |
70 | * syscall_get_return_value - get the return value of a traced system call | |
71 | * @task: task of interest, must be blocked | |
72 | * @regs: task_pt_regs() of @task | |
73 | * | |
74 | * Returns the return value of the successful system call. | |
75 | * This value is meaningless if syscall_get_error() returned nonzero. | |
76 | * | |
77 | * It's only valid to call this when @task is stopped for tracing on exit | |
78 | * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. | |
79 | */ | |
80 | long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs); | |
81 | ||
82 | /** | |
83 | * syscall_set_return_value - change the return value of a traced system call | |
84 | * @task: task of interest, must be blocked | |
85 | * @regs: task_pt_regs() of @task | |
86 | * @error: negative error code, or zero to indicate success | |
87 | * @val: user return value if @error is zero | |
88 | * | |
89 | * This changes the results of the system call that user mode will see. | |
90 | * If @error is zero, the user sees a successful system call with a | |
91 | * return value of @val. If @error is nonzero, it's a negated errno | |
92 | * code; the user sees a failed system call with this errno code. | |
93 | * | |
94 | * It's only valid to call this when @task is stopped for tracing on exit | |
95 | * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. | |
96 | */ | |
97 | void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs, | |
98 | int error, long val); | |
99 | ||
100 | /** | |
101 | * syscall_get_arguments - extract system call parameter values | |
102 | * @task: task of interest, must be blocked | |
103 | * @regs: task_pt_regs() of @task | |
104 | * @i: argument index [0,5] | |
105 | * @n: number of arguments; n+i must be [1,6]. | |
106 | * @args: array filled with argument values | |
107 | * | |
108 | * Fetches @n arguments to the system call starting with the @i'th argument | |
109 | * (from 0 through 5). Argument @i is stored in @args[0], and so on. | |
110 | * An arch inline version is probably optimal when @i and @n are constants. | |
111 | * | |
112 | * It's only valid to call this when @task is stopped for tracing on | |
113 | * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. | |
114 | * It's invalid to call this with @i + @n > 6; we only support system calls | |
115 | * taking up to 6 arguments. | |
116 | */ | |
117 | void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, | |
118 | unsigned int i, unsigned int n, unsigned long *args); | |
119 | ||
120 | /** | |
121 | * syscall_set_arguments - change system call parameter value | |
122 | * @task: task of interest, must be in system call entry tracing | |
123 | * @regs: task_pt_regs() of @task | |
124 | * @i: argument index [0,5] | |
125 | * @n: number of arguments; n+i must be [1,6]. | |
126 | * @args: array of argument values to store | |
127 | * | |
128 | * Changes @n arguments to the system call starting with the @i'th argument. | |
22f30168 | 129 | * Argument @i gets value @args[0], and so on. |
828c365c RM |
130 | * An arch inline version is probably optimal when @i and @n are constants. |
131 | * | |
132 | * It's only valid to call this when @task is stopped for tracing on | |
133 | * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT. | |
134 | * It's invalid to call this with @i + @n > 6; we only support system calls | |
135 | * taking up to 6 arguments. | |
136 | */ | |
137 | void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs, | |
138 | unsigned int i, unsigned int n, | |
139 | const unsigned long *args); | |
140 | ||
141 | #endif /* _ASM_SYSCALL_H */ |