Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Access to user system call parameters and results
4 *
5 * Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
6 *
7 * This file is a stub providing documentation for what functions
8 * arch/ARCH/include/asm/syscall.h files need to define. Most arch definitions
9 * will be simple inlines.
10 *
11 * All of these functions expect to be called with no locks,
12 * and only when the caller is sure that the task of interest
13 * cannot return to user mode while we are looking at it.
14 */
15
16#ifndef _ASM_SYSCALL_H
17#define _ASM_SYSCALL_H 1
18
19struct task_struct;
20struct pt_regs;
21
22/**
23 * syscall_get_nr - find what system call a task is executing
24 * @task: task of interest, must be blocked
25 * @regs: task_pt_regs() of @task
26 *
27 * If @task is executing a system call or is at system call
28 * tracing about to attempt one, returns the system call number.
29 * If @task is not executing a system call, i.e. it's blocked
30 * inside the kernel for a fault or signal, returns -1.
31 *
32 * Note this returns int even on 64-bit machines. Only 32 bits of
33 * system call number can be meaningful. If the actual arch value
34 * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
35 *
36 * It's only valid to call this when @task is known to be blocked.
37 */
38int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
39
40/**
41 * syscall_set_nr - change the system call a task is executing
42 * @task: task of interest, must be blocked
43 * @regs: task_pt_regs() of @task
44 * @nr: system call number
45 *
46 * Changes the system call number @task is about to execute.
47 *
48 * It's only valid to call this when @task is stopped for tracing on
49 * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
50 * %SYSCALL_WORK_SYSCALL_AUDIT.
51 */
52void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr);
53
54/**
55 * syscall_rollback - roll back registers after an aborted system call
56 * @task: task of interest, must be in system call exit tracing
57 * @regs: task_pt_regs() of @task
58 *
59 * It's only valid to call this when @task is stopped for system
60 * call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or
61 * %SYSCALL_WORK_SYSCALL_AUDIT), after ptrace_report_syscall_entry()
62 * returned nonzero to prevent the system call from taking place.
63 *
64 * This rolls back the register state in @regs so it's as if the
65 * system call instruction was a no-op. The registers containing
66 * the system call number and arguments are as they were before the
67 * system call instruction. This may not be the same as what the
68 * register state looked like at system call entry tracing.
69 */
70void syscall_rollback(struct task_struct *task, struct pt_regs *regs);
71
72/**
73 * syscall_get_error - check result of traced system call
74 * @task: task of interest, must be blocked
75 * @regs: task_pt_regs() of @task
76 *
77 * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
78 *
79 * It's only valid to call this when @task is stopped for tracing on exit
80 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
81 * %SYSCALL_WORK_SYSCALL_AUDIT.
82 */
83long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
84
85/**
86 * syscall_get_return_value - get the return value of a traced system call
87 * @task: task of interest, must be blocked
88 * @regs: task_pt_regs() of @task
89 *
90 * Returns the return value of the successful system call.
91 * This value is meaningless if syscall_get_error() returned nonzero.
92 *
93 * It's only valid to call this when @task is stopped for tracing on exit
94 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
95 * %SYSCALL_WORK_SYSCALL_AUDIT.
96 */
97long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
98
99/**
100 * syscall_set_return_value - change the return value of a traced system call
101 * @task: task of interest, must be blocked
102 * @regs: task_pt_regs() of @task
103 * @error: negative error code, or zero to indicate success
104 * @val: user return value if @error is zero
105 *
106 * This changes the results of the system call that user mode will see.
107 * If @error is zero, the user sees a successful system call with a
108 * return value of @val. If @error is nonzero, it's a negated errno
109 * code; the user sees a failed system call with this errno code.
110 *
111 * It's only valid to call this when @task is stopped for tracing on exit
112 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
113 * %SYSCALL_WORK_SYSCALL_AUDIT.
114 */
115void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
116 int error, long val);
117
118/**
119 * syscall_get_arguments - extract system call parameter values
120 * @task: task of interest, must be blocked
121 * @regs: task_pt_regs() of @task
122 * @args: array filled with argument values
123 *
124 * Fetches 6 arguments to the system call. First argument is stored in
125* @args[0], and so on.
126 *
127 * It's only valid to call this when @task is stopped for tracing on
128 * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
129 * %SYSCALL_WORK_SYSCALL_AUDIT.
130 */
131void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
132 unsigned long *args);
133
134/**
135 * syscall_set_arguments - change system call parameter value
136 * @task: task of interest, must be in system call entry tracing
137 * @regs: task_pt_regs() of @task
138 * @args: array of argument values to store
139 *
140 * Changes 6 arguments to the system call.
141 * The first argument gets value @args[0], and so on.
142 *
143 * It's only valid to call this when @task is stopped for tracing on
144 * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
145 * %SYSCALL_WORK_SYSCALL_AUDIT.
146 */
147void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
148 const unsigned long *args);
149
150/**
151 * syscall_get_arch - return the AUDIT_ARCH for the current system call
152 * @task: task of interest, must be blocked
153 *
154 * Returns the AUDIT_ARCH_* based on the system call convention in use.
155 *
156 * It's only valid to call this when @task is stopped on entry to a system
157 * call, due to %SYSCALL_WORK_SYSCALL_TRACE, %SYSCALL_WORK_SYSCALL_AUDIT, or
158 * %SYSCALL_WORK_SECCOMP.
159 *
160 * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
161 * provide an implementation of this.
162 */
163int syscall_get_arch(struct task_struct *task);
164#endif /* _ASM_SYSCALL_H */