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 
mips_syscall_is_indirect(struct task_struct * task,struct pt_regs * regs)29 static 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 
syscall_get_nr(struct task_struct * task,struct pt_regs * regs)38 static inline long syscall_get_nr(struct task_struct *task,
39 				  struct pt_regs *regs)
40 {
41 	return current_thread_info()->syscall;
42 }
43 
mips_syscall_update_nr(struct task_struct * task,struct pt_regs * regs)44 static inline void mips_syscall_update_nr(struct task_struct *task,
45 					  struct pt_regs *regs)
46 {
47 	/*
48 	 * v0 is the system call number, except for O32 ABI syscall(), where it
49 	 * ends up in a0.
50 	 */
51 	if (mips_syscall_is_indirect(task, regs))
52 		task_thread_info(task)->syscall = regs->regs[4];
53 	else
54 		task_thread_info(task)->syscall = regs->regs[2];
55 }
56 
mips_get_syscall_arg(unsigned long * arg,struct task_struct * task,struct pt_regs * regs,unsigned int n)57 static inline void mips_get_syscall_arg(unsigned long *arg,
58 	struct task_struct *task, struct pt_regs *regs, unsigned int n)
59 {
60 	unsigned long usp __maybe_unused = regs->regs[29];
61 
62 	switch (n) {
63 	case 0: case 1: case 2: case 3:
64 		*arg = regs->regs[4 + n];
65 
66 		return;
67 
68 #ifdef CONFIG_32BIT
69 	case 4: case 5: case 6: case 7:
70 		get_user(*arg, (int *)usp + n);
71 		return;
72 #endif
73 
74 #ifdef CONFIG_64BIT
75 	case 4: case 5: case 6: case 7:
76 #ifdef CONFIG_MIPS32_O32
77 		if (test_tsk_thread_flag(task, TIF_32BIT_REGS))
78 			get_user(*arg, (int *)usp + n);
79 		else
80 #endif
81 			*arg = regs->regs[4 + n];
82 
83 		return;
84 #endif
85 
86 	default:
87 		BUG();
88 	}
89 
90 	unreachable();
91 }
92 
syscall_get_error(struct task_struct * task,struct pt_regs * regs)93 static inline long syscall_get_error(struct task_struct *task,
94 				     struct pt_regs *regs)
95 {
96 	return regs->regs[7] ? -regs->regs[2] : 0;
97 }
98 
syscall_get_return_value(struct task_struct * task,struct pt_regs * regs)99 static inline long syscall_get_return_value(struct task_struct *task,
100 					    struct pt_regs *regs)
101 {
102 	return regs->regs[2];
103 }
104 
syscall_rollback(struct task_struct * task,struct pt_regs * regs)105 static inline void syscall_rollback(struct task_struct *task,
106 				    struct pt_regs *regs)
107 {
108 	/* Do nothing */
109 }
110 
syscall_set_return_value(struct task_struct * task,struct pt_regs * regs,int error,long val)111 static inline void syscall_set_return_value(struct task_struct *task,
112 					    struct pt_regs *regs,
113 					    int error, long val)
114 {
115 	if (error) {
116 		regs->regs[2] = -error;
117 		regs->regs[7] = 1;
118 	} else {
119 		regs->regs[2] = val;
120 		regs->regs[7] = 0;
121 	}
122 }
123 
syscall_get_arguments(struct task_struct * task,struct pt_regs * regs,unsigned long * args)124 static inline void syscall_get_arguments(struct task_struct *task,
125 					 struct pt_regs *regs,
126 					 unsigned long *args)
127 {
128 	unsigned int i = 0;
129 	unsigned int n = 6;
130 
131 	/* O32 ABI syscall() */
132 	if (mips_syscall_is_indirect(task, regs))
133 		i++;
134 
135 	while (n--)
136 		mips_get_syscall_arg(args++, task, regs, i++);
137 }
138 
139 extern const unsigned long sys_call_table[];
140 extern const unsigned long sys32_call_table[];
141 extern const unsigned long sysn32_call_table[];
142 
syscall_get_arch(struct task_struct * task)143 static inline int syscall_get_arch(struct task_struct *task)
144 {
145 	int arch = AUDIT_ARCH_MIPS;
146 #ifdef CONFIG_64BIT
147 	if (!test_tsk_thread_flag(task, TIF_32BIT_REGS)) {
148 		arch |= __AUDIT_ARCH_64BIT;
149 		/* N32 sets only TIF_32BIT_ADDR */
150 		if (test_tsk_thread_flag(task, TIF_32BIT_ADDR))
151 			arch |= __AUDIT_ARCH_CONVENTION_MIPS64_N32;
152 	}
153 #endif
154 #if defined(__LITTLE_ENDIAN)
155 	arch |=  __AUDIT_ARCH_LE;
156 #endif
157 	return arch;
158 }
159 
160 #endif	/* __ASM_MIPS_SYSCALL_H */
161