Linux kernel mirror (for testing)
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1// SPDX-License-Identifier: GPL-2.0
2// Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
3// Copyright (C) 2005-2017 Andes Technology Corporation
4
5#ifndef _ASM_NDS32_SYSCALL_H
6#define _ASM_NDS32_SYSCALL_H 1
7
8#include <linux/err.h>
9struct task_struct;
10struct pt_regs;
11
12/**
13 * syscall_get_nr - find what system call a task is executing
14 * @task: task of interest, must be blocked
15 * @regs: task_pt_regs() of @task
16 *
17 * If @task is executing a system call or is at system call
18 * tracing about to attempt one, returns the system call number.
19 * If @task is not executing a system call, i.e. it's blocked
20 * inside the kernel for a fault or signal, returns -1.
21 *
22 * Note this returns int even on 64-bit machines. Only 32 bits of
23 * system call number can be meaningful. If the actual arch value
24 * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
25 *
26 * It's only valid to call this when @task is known to be blocked.
27 */
28int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
29{
30 return regs->syscallno;
31}
32
33/**
34 * syscall_rollback - roll back registers after an aborted system call
35 * @task: task of interest, must be in system call exit tracing
36 * @regs: task_pt_regs() of @task
37 *
38 * It's only valid to call this when @task is stopped for system
39 * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
40 * after tracehook_report_syscall_entry() returned nonzero to prevent
41 * the system call from taking place.
42 *
43 * This rolls back the register state in @regs so it's as if the
44 * system call instruction was a no-op. The registers containing
45 * the system call number and arguments are as they were before the
46 * system call instruction. This may not be the same as what the
47 * register state looked like at system call entry tracing.
48 */
49void syscall_rollback(struct task_struct *task, struct pt_regs *regs)
50{
51 regs->uregs[0] = regs->orig_r0;
52}
53
54/**
55 * syscall_get_error - check result of traced system call
56 * @task: task of interest, must be blocked
57 * @regs: task_pt_regs() of @task
58 *
59 * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
60 *
61 * It's only valid to call this when @task is stopped for tracing on exit
62 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
63 */
64long syscall_get_error(struct task_struct *task, struct pt_regs *regs)
65{
66 unsigned long error = regs->uregs[0];
67 return IS_ERR_VALUE(error) ? error : 0;
68}
69
70/**
71 * syscall_get_return_value - get the return value of a traced system call
72 * @task: task of interest, must be blocked
73 * @regs: task_pt_regs() of @task
74 *
75 * Returns the return value of the successful system call.
76 * This value is meaningless if syscall_get_error() returned nonzero.
77 *
78 * It's only valid to call this when @task is stopped for tracing on exit
79 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
80 */
81long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
82{
83 return regs->uregs[0];
84}
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 */
101void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
102 int error, long val)
103{
104 regs->uregs[0] = (long)error ? error : val;
105}
106
107/**
108 * syscall_get_arguments - extract system call parameter values
109 * @task: task of interest, must be blocked
110 * @regs: task_pt_regs() of @task
111 * @args: array filled with argument values
112 *
113 * Fetches 6 arguments to the system call (from 0 through 5). The first
114 * argument is stored in @args[0], and so on.
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 */
119#define SYSCALL_MAX_ARGS 6
120void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
121 unsigned long *args)
122{
123 args[0] = regs->orig_r0;
124 args++;
125 memcpy(args, ®s->uregs[0] + 1, 5 * sizeof(args[0]));
126}
127
128/**
129 * syscall_set_arguments - change system call parameter value
130 * @task: task of interest, must be in system call entry tracing
131 * @regs: task_pt_regs() of @task
132 * @args: array of argument values to store
133 *
134 * Changes 6 arguments to the system call. The first argument gets value
135 * @args[0], and so on.
136 *
137 * It's only valid to call this when @task is stopped for tracing on
138 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
139 */
140void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
141 const unsigned long *args)
142{
143 regs->orig_r0 = args[0];
144 args++;
145
146 memcpy(®s->uregs[0] + 1, args, 5 * sizeof(args[0]));
147}
148#endif /* _ASM_NDS32_SYSCALL_H */