summaryrefslogtreecommitdiff
path: root/include/asm-generic/syscall.h
blob: 5a80fe728dc8b6e19a615b87c0111fabc63bc6dc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Access to user system call parameters and results
 *
 * Copyright (C) 2008-2009 Red Hat, Inc.  All rights reserved.
 *
 * This file is a stub providing documentation for what functions
 * asm-ARCH/syscall.h files need to define.  Most arch definitions
 * will be simple inlines.
 *
 * All of these functions expect to be called with no locks,
 * and only when the caller is sure that the task of interest
 * cannot return to user mode while we are looking at it.
 */

#ifndef _ASM_SYSCALL_H
#define _ASM_SYSCALL_H	1

struct task_struct;
struct pt_regs;

/**
 * syscall_get_nr - find what system call a task is executing
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 *
 * If @task is executing a system call or is at system call
 * tracing about to attempt one, returns the system call number.
 * If @task is not executing a system call, i.e. it's blocked
 * inside the kernel for a fault or signal, returns -1.
 *
 * Note this returns int even on 64-bit machines.  Only 32 bits of
 * system call number can be meaningful.  If the actual arch value
 * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
 *
 * It's only valid to call this when @task is known to be blocked.
 */
int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);

/**
 * syscall_rollback - roll back registers after an aborted system call
 * @task:	task of interest, must be in system call exit tracing
 * @regs:	task_pt_regs() of @task
 *
 * It's only valid to call this when @task is stopped for system
 * call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or
 * %SYSCALL_WORK_SYSCALL_AUDIT), after ptrace_report_syscall_entry()
 * returned nonzero to prevent the system call from taking place.
 *
 * This rolls back the register state in @regs so it's as if the
 * system call instruction was a no-op.  The registers containing
 * the system call number and arguments are as they were before the
 * system call instruction.  This may not be the same as what the
 * register state looked like at system call entry tracing.
 */
void syscall_rollback(struct task_struct *task, struct pt_regs *regs);

/**
 * syscall_get_error - check result of traced system call
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 *
 * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
 *
 * It's only valid to call this when @task is stopped for tracing on exit
 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
 * %SYSCALL_WORK_SYSCALL_AUDIT.
 */
long syscall_get_error(struct task_struct *task, struct pt_regs *regs);

/**
 * syscall_get_return_value - get the return value of a traced system call
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 *
 * Returns the return value of the successful system call.
 * This value is meaningless if syscall_get_error() returned nonzero.
 *
 * It's only valid to call this when @task is stopped for tracing on exit
 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
 * %SYSCALL_WORK_SYSCALL_AUDIT.
 */
long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);

/**
 * syscall_set_return_value - change the return value of a traced system call
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 * @error:	negative error code, or zero to indicate success
 * @val:	user return value if @error is zero
 *
 * This changes the results of the system call that user mode will see.
 * If @error is zero, the user sees a successful system call with a
 * return value of @val.  If @error is nonzero, it's a negated errno
 * code; the user sees a failed system call with this errno code.
 *
 * It's only valid to call this when @task is stopped for tracing on exit
 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
 * %SYSCALL_WORK_SYSCALL_AUDIT.
 */
void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
			      int error, long val);

/**
 * syscall_get_arguments - extract system call parameter values
 * @task:	task of interest, must be blocked
 * @regs:	task_pt_regs() of @task
 * @args:	array filled with argument values
 *
 * Fetches 6 arguments to the system call.  First argument is stored in
*  @args[0], and so on.
 *
 * It's only valid to call this when @task is stopped for tracing on
 * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
 * %SYSCALL_WORK_SYSCALL_AUDIT.
 */
void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
			   unsigned long *args);

/**
 * syscall_get_arch - return the AUDIT_ARCH for the current system call
 * @task:	task of interest, must be blocked
 *
 * Returns the AUDIT_ARCH_* based on the system call convention in use.
 *
 * It's only valid to call this when @task is stopped on entry to a system
 * call, due to %SYSCALL_WORK_SYSCALL_TRACE, %SYSCALL_WORK_SYSCALL_AUDIT, or
 * %SYSCALL_WORK_SECCOMP.
 *
 * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
 * provide an implementation of this.
 */
int syscall_get_arch(struct task_struct *task);
#endif	/* _ASM_SYSCALL_H */