1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Copyright (C) 2012 ARM Ltd.
4  */
5 #ifndef __ASM_SYSCALL_H
6 #define __ASM_SYSCALL_H
7 
8 #include <uapi/linux/audit.h>
9 #include <linux/compat.h>
10 #include <linux/err.h>
11 
12 typedef long (*syscall_fn_t)(const struct pt_regs *regs);
13 
14 extern const syscall_fn_t sys_call_table[];
15 
16 #ifdef CONFIG_COMPAT
17 extern const syscall_fn_t compat_sys_call_table[];
18 #endif
19 
20 static inline int syscall_get_nr(struct task_struct *task,
21 				 struct pt_regs *regs)
22 {
23 	return regs->syscallno;
24 }
25 
26 static inline void syscall_rollback(struct task_struct *task,
27 				    struct pt_regs *regs)
28 {
29 	regs->regs[0] = regs->orig_x0;
30 }
31 
32 static inline long syscall_get_return_value(struct task_struct *task,
33 					    struct pt_regs *regs)
34 {
35 	unsigned long val = regs->regs[0];
36 
37 	if (is_compat_thread(task_thread_info(task)))
38 		val = sign_extend64(val, 31);
39 
40 	return val;
41 }
42 
43 static inline long syscall_get_error(struct task_struct *task,
44 				     struct pt_regs *regs)
45 {
46 	unsigned long error = syscall_get_return_value(task, regs);
47 
48 	return IS_ERR_VALUE(error) ? error : 0;
49 }
50 
51 static inline void syscall_set_return_value(struct task_struct *task,
52 					    struct pt_regs *regs,
53 					    int error, long val)
54 {
55 	if (error)
56 		val = error;
57 
58 	if (is_compat_thread(task_thread_info(task)))
59 		val = lower_32_bits(val);
60 
61 	regs->regs[0] = val;
62 }
63 
64 static inline void syscall_set_nr(struct task_struct *task,
65 				  struct pt_regs *regs,
66 				  int nr)
67 {
68 	regs->syscallno = nr;
69 	if (nr == -1) {
70 		/*
71 		 * When the syscall number is set to -1, the syscall will be
72 		 * skipped.  In this case the syscall return value has to be
73 		 * set explicitly, otherwise the first syscall argument is
74 		 * returned as the syscall return value.
75 		 */
76 		syscall_set_return_value(task, regs, -ENOSYS, 0);
77 	}
78 }
79 
80 #define SYSCALL_MAX_ARGS 6
81 
82 static inline void syscall_get_arguments(struct task_struct *task,
83 					 struct pt_regs *regs,
84 					 unsigned long *args)
85 {
86 	args[0] = regs->orig_x0;
87 	args++;
88 
89 	memcpy(args, &regs->regs[1], 5 * sizeof(args[0]));
90 }
91 
92 static inline void syscall_set_arguments(struct task_struct *task,
93 					 struct pt_regs *regs,
94 					 const unsigned long *args)
95 {
96 	memcpy(&regs->regs[0], args, 6 * sizeof(args[0]));
97 	/*
98 	 * Also copy the first argument into orig_x0
99 	 * so that syscall_get_arguments() would return it
100 	 * instead of the previous value.
101 	 */
102 	regs->orig_x0 = regs->regs[0];
103 }
104 
105 /*
106  * We don't care about endianness (__AUDIT_ARCH_LE bit) here because
107  * AArch64 has the same system calls both on little- and big- endian.
108  */
109 static inline int syscall_get_arch(struct task_struct *task)
110 {
111 	if (is_compat_thread(task_thread_info(task)))
112 		return AUDIT_ARCH_ARM;
113 
114 	return AUDIT_ARCH_AARCH64;
115 }
116 
117 int syscall_trace_enter(struct pt_regs *regs);
118 void syscall_trace_exit(struct pt_regs *regs);
119 
120 #endif	/* __ASM_SYSCALL_H */
121