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1/*
2 * Access to user system call parameters and results
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * See asm-generic/syscall.h for descriptions of what we must do here.
9 *
10 * Copyright (C) 2012 Ralf Baechle <ralf@linux-mips.org>
11 */
12
13#ifndef __ASM_MIPS_SYSCALL_H
14#define __ASM_MIPS_SYSCALL_H
15
16#include <linux/compiler.h>
17#include <uapi/linux/audit.h>
18#include <linux/elf-em.h>
19#include <linux/kernel.h>
20#include <linux/sched.h>
21#include <linux/uaccess.h>
22#include <asm/ptrace.h>
23#include <asm/unistd.h>
24
25#ifndef __NR_syscall /* Only defined if _MIPS_SIM == _MIPS_SIM_ABI32 */
26#define __NR_syscall 4000
27#endif
28
29static inline bool mips_syscall_is_indirect(struct task_struct *task,
30 struct pt_regs *regs)
31{
32 /* O32 ABI syscall() - Either 64-bit with O32 or 32-bit */
33 return (IS_ENABLED(CONFIG_32BIT) ||
34 test_tsk_thread_flag(task, TIF_32BIT_REGS)) &&
35 (regs->regs[2] == __NR_syscall);
36}
37
38static inline long syscall_get_nr(struct task_struct *task,
39 struct pt_regs *regs)
40{
41 return task_thread_info(task)->syscall;
42}
43
44static inline void syscall_set_nr(struct task_struct *task,
45 struct pt_regs *regs,
46 int nr)
47{
48 /*
49 * New syscall number has to be assigned to regs[2] because
50 * it is loaded from there unconditionally after return from
51 * syscall_trace_enter() invocation.
52 *
53 * Consequently, if the syscall was indirect and nr != __NR_syscall,
54 * then after this assignment the syscall will cease to be indirect.
55 */
56 task_thread_info(task)->syscall = regs->regs[2] = nr;
57}
58
59static inline void mips_syscall_update_nr(struct task_struct *task,
60 struct pt_regs *regs)
61{
62 /*
63 * v0 is the system call number, except for O32 ABI syscall(), where it
64 * ends up in a0.
65 */
66 if (mips_syscall_is_indirect(task, regs))
67 task_thread_info(task)->syscall = regs->regs[4];
68 else
69 task_thread_info(task)->syscall = regs->regs[2];
70}
71
72static inline void mips_get_syscall_arg(unsigned long *arg,
73 struct task_struct *task, struct pt_regs *regs, unsigned int n)
74{
75#ifdef CONFIG_32BIT
76 switch (n) {
77 case 0: case 1: case 2: case 3:
78 *arg = regs->regs[4 + n];
79 return;
80 case 4: case 5: case 6: case 7:
81 *arg = regs->args[n];
82 return;
83 }
84#else
85 *arg = regs->regs[4 + n];
86 if ((IS_ENABLED(CONFIG_MIPS32_O32) &&
87 test_tsk_thread_flag(task, TIF_32BIT_REGS)))
88 *arg = (unsigned int)*arg;
89#endif
90}
91
92static inline void mips_set_syscall_arg(unsigned long *arg,
93 struct task_struct *task, struct pt_regs *regs, unsigned int n)
94{
95#ifdef CONFIG_32BIT
96 switch (n) {
97 case 0: case 1: case 2: case 3:
98 regs->regs[4 + n] = *arg;
99 return;
100 case 4: case 5: case 6: case 7:
101 *arg = regs->args[n] = *arg;
102 return;
103 }
104#else
105 regs->regs[4 + n] = *arg;
106#endif
107}
108
109static inline long syscall_get_error(struct task_struct *task,
110 struct pt_regs *regs)
111{
112 return regs->regs[7] ? -regs->regs[2] : 0;
113}
114
115static inline long syscall_get_return_value(struct task_struct *task,
116 struct pt_regs *regs)
117{
118 return regs->regs[2];
119}
120
121static inline void syscall_rollback(struct task_struct *task,
122 struct pt_regs *regs)
123{
124 /* Do nothing */
125}
126
127static inline void syscall_set_return_value(struct task_struct *task,
128 struct pt_regs *regs,
129 int error, long val)
130{
131 if (error) {
132 regs->regs[2] = -error;
133 regs->regs[7] = 1;
134 } else {
135 regs->regs[2] = val;
136 regs->regs[7] = 0;
137 }
138}
139
140static inline void syscall_get_arguments(struct task_struct *task,
141 struct pt_regs *regs,
142 unsigned long *args)
143{
144 unsigned int i = 0;
145 unsigned int n = 6;
146
147 /* O32 ABI syscall() */
148 if (mips_syscall_is_indirect(task, regs))
149 i++;
150
151 while (n--)
152 mips_get_syscall_arg(args++, task, regs, i++);
153}
154
155static inline void syscall_set_arguments(struct task_struct *task,
156 struct pt_regs *regs,
157 unsigned long *args)
158{
159 unsigned int i = 0;
160 unsigned int n = 6;
161
162 while (n--)
163 mips_set_syscall_arg(args++, task, regs, i++);
164}
165
166extern const unsigned long sys_call_table[];
167extern const unsigned long sys32_call_table[];
168extern const unsigned long sysn32_call_table[];
169
170static inline int syscall_get_arch(struct task_struct *task)
171{
172 int arch = AUDIT_ARCH_MIPS;
173#ifdef CONFIG_64BIT
174 if (!test_tsk_thread_flag(task, TIF_32BIT_REGS)) {
175 arch |= __AUDIT_ARCH_64BIT;
176 /* N32 sets only TIF_32BIT_ADDR */
177 if (test_tsk_thread_flag(task, TIF_32BIT_ADDR))
178 arch |= __AUDIT_ARCH_CONVENTION_MIPS64_N32;
179 }
180#endif
181#if defined(__LITTLE_ENDIAN)
182 arch |= __AUDIT_ARCH_LE;
183#endif
184 return arch;
185}
186
187#endif /* __ASM_MIPS_SYSCALL_H */
188

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source code of linux/arch/mips/include/asm/syscall.h