1 /*
2  * Access to user system call parameters and results
3  *
4  * Copyright (C) 2008-2009 Red Hat, Inc.  All rights reserved.
5  *
6  * This copyrighted material is made available to anyone wishing to use,
7  * modify, copy, or redistribute it subject to the terms and conditions
8  * of the GNU General Public License v.2.
9  *
10  * See asm-generic/syscall.h for descriptions of what we must do here.
11  */
12 
13 #ifndef _ASM_X86_SYSCALL_H
14 #define _ASM_X86_SYSCALL_H
15 
16 #include <linux/sched.h>
17 #include <linux/err.h>
18 #include <asm/asm-offsets.h>	/* For NR_syscalls */
19 
20 extern const unsigned long sys_call_table[];
21 
22 /*
23  * Only the low 32 bits of orig_ax are meaningful, so we return int.
24  * This importantly ignores the high bits on 64-bit, so comparisons
25  * sign-extend the low 32 bits.
26  */
syscall_get_nr(struct task_struct * task,struct pt_regs * regs)27 static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
28 {
29 	return regs->orig_ax;
30 }
31 
syscall_rollback(struct task_struct * task,struct pt_regs * regs)32 static inline void syscall_rollback(struct task_struct *task,
33 				    struct pt_regs *regs)
34 {
35 	regs->ax = regs->orig_ax;
36 }
37 
syscall_get_error(struct task_struct * task,struct pt_regs * regs)38 static inline long syscall_get_error(struct task_struct *task,
39 				     struct pt_regs *regs)
40 {
41 	unsigned long error = regs->ax;
42 #ifdef CONFIG_IA32_EMULATION
43 	/*
44 	 * TS_COMPAT is set for 32-bit syscall entries and then
45 	 * remains set until we return to user mode.
46 	 */
47 	if (task_thread_info(task)->status & TS_COMPAT)
48 		/*
49 		 * Sign-extend the value so (int)-EFOO becomes (long)-EFOO
50 		 * and will match correctly in comparisons.
51 		 */
52 		error = (long) (int) error;
53 #endif
54 	return IS_ERR_VALUE(error) ? error : 0;
55 }
56 
syscall_get_return_value(struct task_struct * task,struct pt_regs * regs)57 static inline long syscall_get_return_value(struct task_struct *task,
58 					    struct pt_regs *regs)
59 {
60 	return regs->ax;
61 }
62 
syscall_set_return_value(struct task_struct * task,struct pt_regs * regs,int error,long val)63 static inline void syscall_set_return_value(struct task_struct *task,
64 					    struct pt_regs *regs,
65 					    int error, long val)
66 {
67 	regs->ax = (long) error ?: val;
68 }
69 
70 #ifdef CONFIG_X86_32
71 
syscall_get_arguments(struct task_struct * task,struct pt_regs * regs,unsigned int i,unsigned int n,unsigned long * args)72 static inline void syscall_get_arguments(struct task_struct *task,
73 					 struct pt_regs *regs,
74 					 unsigned int i, unsigned int n,
75 					 unsigned long *args)
76 {
77 	BUG_ON(i + n > 6);
78 	memcpy(args, &regs->bx + i, n * sizeof(args[0]));
79 }
80 
syscall_set_arguments(struct task_struct * task,struct pt_regs * regs,unsigned int i,unsigned int n,const unsigned long * args)81 static inline void syscall_set_arguments(struct task_struct *task,
82 					 struct pt_regs *regs,
83 					 unsigned int i, unsigned int n,
84 					 const unsigned long *args)
85 {
86 	BUG_ON(i + n > 6);
87 	memcpy(&regs->bx + i, args, n * sizeof(args[0]));
88 }
89 
90 #else	 /* CONFIG_X86_64 */
91 
syscall_get_arguments(struct task_struct * task,struct pt_regs * regs,unsigned int i,unsigned int n,unsigned long * args)92 static inline void syscall_get_arguments(struct task_struct *task,
93 					 struct pt_regs *regs,
94 					 unsigned int i, unsigned int n,
95 					 unsigned long *args)
96 {
97 # ifdef CONFIG_IA32_EMULATION
98 	if (task_thread_info(task)->status & TS_COMPAT)
99 		switch (i) {
100 		case 0:
101 			if (!n--) break;
102 			*args++ = regs->bx;
103 		case 1:
104 			if (!n--) break;
105 			*args++ = regs->cx;
106 		case 2:
107 			if (!n--) break;
108 			*args++ = regs->dx;
109 		case 3:
110 			if (!n--) break;
111 			*args++ = regs->si;
112 		case 4:
113 			if (!n--) break;
114 			*args++ = regs->di;
115 		case 5:
116 			if (!n--) break;
117 			*args++ = regs->bp;
118 		case 6:
119 			if (!n--) break;
120 		default:
121 			BUG();
122 			break;
123 		}
124 	else
125 # endif
126 		switch (i) {
127 		case 0:
128 			if (!n--) break;
129 			*args++ = regs->di;
130 		case 1:
131 			if (!n--) break;
132 			*args++ = regs->si;
133 		case 2:
134 			if (!n--) break;
135 			*args++ = regs->dx;
136 		case 3:
137 			if (!n--) break;
138 			*args++ = regs->r10;
139 		case 4:
140 			if (!n--) break;
141 			*args++ = regs->r8;
142 		case 5:
143 			if (!n--) break;
144 			*args++ = regs->r9;
145 		case 6:
146 			if (!n--) break;
147 		default:
148 			BUG();
149 			break;
150 		}
151 }
152 
syscall_set_arguments(struct task_struct * task,struct pt_regs * regs,unsigned int i,unsigned int n,const unsigned long * args)153 static inline void syscall_set_arguments(struct task_struct *task,
154 					 struct pt_regs *regs,
155 					 unsigned int i, unsigned int n,
156 					 const unsigned long *args)
157 {
158 # ifdef CONFIG_IA32_EMULATION
159 	if (task_thread_info(task)->status & TS_COMPAT)
160 		switch (i) {
161 		case 0:
162 			if (!n--) break;
163 			regs->bx = *args++;
164 		case 1:
165 			if (!n--) break;
166 			regs->cx = *args++;
167 		case 2:
168 			if (!n--) break;
169 			regs->dx = *args++;
170 		case 3:
171 			if (!n--) break;
172 			regs->si = *args++;
173 		case 4:
174 			if (!n--) break;
175 			regs->di = *args++;
176 		case 5:
177 			if (!n--) break;
178 			regs->bp = *args++;
179 		case 6:
180 			if (!n--) break;
181 		default:
182 			BUG();
183 			break;
184 		}
185 	else
186 # endif
187 		switch (i) {
188 		case 0:
189 			if (!n--) break;
190 			regs->di = *args++;
191 		case 1:
192 			if (!n--) break;
193 			regs->si = *args++;
194 		case 2:
195 			if (!n--) break;
196 			regs->dx = *args++;
197 		case 3:
198 			if (!n--) break;
199 			regs->r10 = *args++;
200 		case 4:
201 			if (!n--) break;
202 			regs->r8 = *args++;
203 		case 5:
204 			if (!n--) break;
205 			regs->r9 = *args++;
206 		case 6:
207 			if (!n--) break;
208 		default:
209 			BUG();
210 			break;
211 		}
212 }
213 
214 #endif	/* CONFIG_X86_32 */
215 
216 #endif	/* _ASM_X86_SYSCALL_H */
217