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>
9 struct task_struct;
10 struct 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 */
syscall_get_nr(struct task_struct * task,struct pt_regs * regs)28 int 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 */
syscall_rollback(struct task_struct * task,struct pt_regs * regs)49 void 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 */
syscall_get_error(struct task_struct * task,struct pt_regs * regs)64 long 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 */
syscall_get_return_value(struct task_struct * task,struct pt_regs * regs)81 long 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 */
syscall_set_return_value(struct task_struct * task,struct pt_regs * regs,int error,long val)101 void 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 * @i: argument index [0,5]
112 * @n: number of arguments; n+i must be [1,6].
113 * @args: array filled with argument values
114 *
115 * Fetches @n arguments to the system call starting with the @i'th argument
116 * (from 0 through 5). Argument @i is stored in @args[0], and so on.
117 * An arch inline version is probably optimal when @i and @n are constants.
118 *
119 * It's only valid to call this when @task is stopped for tracing on
120 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
121 * It's invalid to call this with @i + @n > 6; we only support system calls
122 * taking up to 6 arguments.
123 */
124 #define SYSCALL_MAX_ARGS 6
syscall_get_arguments(struct task_struct * task,struct pt_regs * regs,unsigned int i,unsigned int n,unsigned long * args)125 void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
126 unsigned int i, unsigned int n, unsigned long *args)
127 {
128 if (n == 0)
129 return;
130 if (i + n > SYSCALL_MAX_ARGS) {
131 unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
132 unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
133 pr_warning("%s called with max args %d, handling only %d\n",
134 __func__, i + n, SYSCALL_MAX_ARGS);
135 memset(args_bad, 0, n_bad * sizeof(args[0]));
136 memset(args_bad, 0, n_bad * sizeof(args[0]));
137 }
138
139 if (i == 0) {
140 args[0] = regs->orig_r0;
141 args++;
142 i++;
143 n--;
144 }
145
146 memcpy(args, ®s->uregs[0] + i, n * sizeof(args[0]));
147 }
148
149 /**
150 * syscall_set_arguments - change system call parameter value
151 * @task: task of interest, must be in system call entry tracing
152 * @regs: task_pt_regs() of @task
153 * @i: argument index [0,5]
154 * @n: number of arguments; n+i must be [1,6].
155 * @args: array of argument values to store
156 *
157 * Changes @n arguments to the system call starting with the @i'th argument.
158 * Argument @i gets value @args[0], and so on.
159 * An arch inline version is probably optimal when @i and @n are constants.
160 *
161 * It's only valid to call this when @task is stopped for tracing on
162 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
163 * It's invalid to call this with @i + @n > 6; we only support system calls
164 * taking up to 6 arguments.
165 */
syscall_set_arguments(struct task_struct * task,struct pt_regs * regs,unsigned int i,unsigned int n,const unsigned long * args)166 void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
167 unsigned int i, unsigned int n,
168 const unsigned long *args)
169 {
170 if (n == 0)
171 return;
172
173 if (i + n > SYSCALL_MAX_ARGS) {
174 pr_warn("%s called with max args %d, handling only %d\n",
175 __func__, i + n, SYSCALL_MAX_ARGS);
176 n = SYSCALL_MAX_ARGS - i;
177 }
178
179 if (i == 0) {
180 regs->orig_r0 = args[0];
181 args++;
182 i++;
183 n--;
184 }
185
186 memcpy(®s->uregs[0] + i, args, n * sizeof(args[0]));
187 }
188 #endif /* _ASM_NDS32_SYSCALL_H */
189