1 /* syscall parameter access functions
2 *
3 * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12 #ifndef _ASM_SYSCALL_H
13 #define _ASM_SYSCALL_H
14
15 #include <linux/err.h>
16 #include <asm/ptrace.h>
17
18 /*
19 * Get the system call number or -1
20 */
syscall_get_nr(struct task_struct * task,struct pt_regs * regs)21 static inline long syscall_get_nr(struct task_struct *task,
22 struct pt_regs *regs)
23 {
24 return regs->syscallno;
25 }
26
27 /*
28 * Restore the clobbered GR8 register
29 * (1st syscall arg was overwritten with syscall return or error)
30 */
syscall_rollback(struct task_struct * task,struct pt_regs * regs)31 static inline void syscall_rollback(struct task_struct *task,
32 struct pt_regs *regs)
33 {
34 regs->gr8 = regs->orig_gr8;
35 }
36
37 /*
38 * See if the syscall return value is an error, returning it if it is and 0 if
39 * not
40 */
syscall_get_error(struct task_struct * task,struct pt_regs * regs)41 static inline long syscall_get_error(struct task_struct *task,
42 struct pt_regs *regs)
43 {
44 return IS_ERR_VALUE(regs->gr8) ? regs->gr8 : 0;
45 }
46
47 /*
48 * Get the syscall return value
49 */
syscall_get_return_value(struct task_struct * task,struct pt_regs * regs)50 static inline long syscall_get_return_value(struct task_struct *task,
51 struct pt_regs *regs)
52 {
53 return regs->gr8;
54 }
55
56 /*
57 * Set the syscall return value
58 */
syscall_set_return_value(struct task_struct * task,struct pt_regs * regs,int error,long val)59 static inline void syscall_set_return_value(struct task_struct *task,
60 struct pt_regs *regs,
61 int error, long val)
62 {
63 if (error)
64 regs->gr8 = -error;
65 else
66 regs->gr8 = val;
67 }
68
69 /*
70 * Retrieve the system call arguments
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 /*
78 * Do this simply for now. If we need to start supporting
79 * fetching arguments from arbitrary indices, this will need some
80 * extra logic. Presently there are no in-tree users that depend
81 * on this behaviour.
82 */
83 BUG_ON(i);
84
85 /* Argument pattern is: GR8, GR9, GR10, GR11, GR12, GR13 */
86 switch (n) {
87 case 6: args[5] = regs->gr13;
88 case 5: args[4] = regs->gr12;
89 case 4: args[3] = regs->gr11;
90 case 3: args[2] = regs->gr10;
91 case 2: args[1] = regs->gr9;
92 case 1: args[0] = regs->gr8;
93 break;
94 default:
95 BUG();
96 }
97 }
98
99 /*
100 * Alter the system call arguments
101 */
syscall_set_arguments(struct task_struct * task,struct pt_regs * regs,unsigned int i,unsigned int n,const unsigned long * args)102 static inline void syscall_set_arguments(struct task_struct *task,
103 struct pt_regs *regs,
104 unsigned int i, unsigned int n,
105 const unsigned long *args)
106 {
107 /* Same note as above applies */
108 BUG_ON(i);
109
110 switch (n) {
111 case 6: regs->gr13 = args[5];
112 case 5: regs->gr12 = args[4];
113 case 4: regs->gr11 = args[3];
114 case 3: regs->gr10 = args[2];
115 case 2: regs->gr9 = args[1];
116 case 1: regs->gr8 = args[0];
117 break;
118 default:
119 BUG();
120 }
121 }
122
123 #endif /* _ASM_SYSCALL_H */
124