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 <uapi/linux/audit.h>
9 #include <linux/err.h>
10 struct task_struct;
11 struct pt_regs;
12
13 /**
14 * syscall_get_nr - find what system call a task is executing
15 * @task: task of interest, must be blocked
16 * @regs: task_pt_regs() of @task
17 *
18 * If @task is executing a system call or is at system call
19 * tracing about to attempt one, returns the system call number.
20 * If @task is not executing a system call, i.e. it's blocked
21 * inside the kernel for a fault or signal, returns -1.
22 *
23 * Note this returns int even on 64-bit machines. Only 32 bits of
24 * system call number can be meaningful. If the actual arch value
25 * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
26 *
27 * It's only valid to call this when @task is known to be blocked.
28 */
29 static inline int
30 syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
31 {
32 return regs->syscallno;
33 }
34
35 /**
36 * syscall_rollback - roll back registers after an aborted system call
37 * @task: task of interest, must be in system call exit tracing
38 * @regs: task_pt_regs() of @task
39 *
40 * It's only valid to call this when @task is stopped for system
41 * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
42 * after tracehook_report_syscall_entry() returned nonzero to prevent
43 * the system call from taking place.
44 *
45 * This rolls back the register state in @regs so it's as if the
46 * system call instruction was a no-op. The registers containing
47 * the system call number and arguments are as they were before the
48 * system call instruction. This may not be the same as what the
49 * register state looked like at system call entry tracing.
50 */
51 static inline void
52 syscall_rollback(struct task_struct *task, struct pt_regs *regs)
53 {
54 regs->uregs[0] = regs->orig_r0;
55 }
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 static inline long
68 syscall_get_error(struct task_struct *task, struct pt_regs *regs)
69 {
70 unsigned long error = regs->uregs[0];
71 return IS_ERR_VALUE(error) ? error : 0;
72 }
73
74 /**
75 * syscall_get_return_value - get the return value of a traced system call
76 * @task: task of interest, must be blocked
77 * @regs: task_pt_regs() of @task
78 *
79 * Returns the return value of the successful system call.
80 * This value is meaningless if syscall_get_error() returned nonzero.
81 *
82 * It's only valid to call this when @task is stopped for tracing on exit
83 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
84 */
85 static inline long
86 syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
87 {
88 return regs->uregs[0];
89 }
90
91 /**
92 * syscall_set_return_value - change the return value of a traced system call
93 * @task: task of interest, must be blocked
94 * @regs: task_pt_regs() of @task
95 * @error: negative error code, or zero to indicate success
96 * @val: user return value if @error is zero
97 *
98 * This changes the results of the system call that user mode will see.
99 * If @error is zero, the user sees a successful system call with a
100 * return value of @val. If @error is nonzero, it's a negated errno
101 * code; the user sees a failed system call with this errno code.
102 *
103 * It's only valid to call this when @task is stopped for tracing on exit
104 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
105 */
106 static inline void
107 syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
108 int error, long val)
109 {
110 regs->uregs[0] = (long)error ? error : val;
111 }
112
113 /**
114 * syscall_get_arguments - extract system call parameter values
115 * @task: task of interest, must be blocked
116 * @regs: task_pt_regs() of @task
117 * @args: array filled with argument values
118 *
119 * Fetches 6 arguments to the system call (from 0 through 5). The first
120 * argument is stored in @args[0], and so on.
121 *
122 * It's only valid to call this when @task is stopped for tracing on
123 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
124 */
125 #define SYSCALL_MAX_ARGS 6
126 static inline void
127 syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
128 unsigned long *args)
129 {
130 args[0] = regs->orig_r0;
131 args++;
132 memcpy(args, ®s->uregs[0] + 1, 5 * sizeof(args[0]));
133 }
134
135 /**
136 * syscall_set_arguments - change system call parameter value
137 * @task: task of interest, must be in system call entry tracing
138 * @regs: task_pt_regs() of @task
139 * @args: array of argument values to store
140 *
141 * Changes 6 arguments to the system call. The first argument gets value
142 * @args[0], and so on.
143 *
144 * It's only valid to call this when @task is stopped for tracing on
145 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
146 */
147 static inline void
148 syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
149 const unsigned long *args)
150 {
151 regs->orig_r0 = args[0];
152 args++;
153
154 memcpy(®s->uregs[0] + 1, args, 5 * sizeof(args[0]));
155 }
156
157 static inline int
158 syscall_get_arch(struct task_struct *task)
159 {
160 return IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)
161 ? AUDIT_ARCH_NDS32BE : AUDIT_ARCH_NDS32;
162 }
163
164 #endif /* _ASM_NDS32_SYSCALL_H */