1 /*
2 * Magic syscall break down functions
3 *
4 * Copyright 2010 Analog Devices Inc.
5 *
6 * Licensed under the GPL-2 or later.
7 */
8
9 #ifndef __ASM_BLACKFIN_SYSCALL_H__
10 #define __ASM_BLACKFIN_SYSCALL_H__
11
12 /*
13 * Blackfin syscalls are simple:
14 * enter:
15 * p0: syscall number
16 * r{0,1,2,3,4,5}: syscall args 0,1,2,3,4,5
17 * exit:
18 * r0: return/error value
19 */
20
21 #include <linux/err.h>
22 #include <linux/sched.h>
23 #include <asm/ptrace.h>
24
25 static inline long
syscall_get_nr(struct task_struct * task,struct pt_regs * regs)26 syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
27 {
28 return regs->p0;
29 }
30
31 static inline void
syscall_rollback(struct task_struct * task,struct pt_regs * regs)32 syscall_rollback(struct task_struct *task, struct pt_regs *regs)
33 {
34 regs->p0 = regs->orig_p0;
35 }
36
37 static inline long
syscall_get_error(struct task_struct * task,struct pt_regs * regs)38 syscall_get_error(struct task_struct *task, struct pt_regs *regs)
39 {
40 return IS_ERR_VALUE(regs->r0) ? regs->r0 : 0;
41 }
42
43 static inline long
syscall_get_return_value(struct task_struct * task,struct pt_regs * regs)44 syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
45 {
46 return regs->r0;
47 }
48
49 static inline void
syscall_set_return_value(struct task_struct * task,struct pt_regs * regs,int error,long val)50 syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
51 int error, long val)
52 {
53 regs->r0 = error ? -error : val;
54 }
55
56 /**
57 * syscall_get_arguments()
58 * @task: unused
59 * @regs: the register layout to extract syscall arguments from
60 * @i: first syscall argument to extract
61 * @n: number of syscall arguments to extract
62 * @args: array to return the syscall arguments in
63 *
64 * args[0] gets i'th argument, args[n - 1] gets the i+n-1'th argument
65 */
66 static inline void
syscall_get_arguments(struct task_struct * task,struct pt_regs * regs,unsigned int i,unsigned int n,unsigned long * args)67 syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
68 unsigned int i, unsigned int n, unsigned long *args)
69 {
70 /*
71 * Assume the ptrace layout doesn't change -- r5 is first in memory,
72 * then r4, ..., then r0. So we simply reverse the ptrace register
73 * array in memory to store into the args array.
74 */
75 long *aregs = ®s->r0 - i;
76
77 BUG_ON(i > 5 || i + n > 6);
78
79 while (n--)
80 *args++ = *aregs--;
81 }
82
83 /* See syscall_get_arguments() comments */
84 static inline void
syscall_set_arguments(struct task_struct * task,struct pt_regs * regs,unsigned int i,unsigned int n,const unsigned long * args)85 syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
86 unsigned int i, unsigned int n, const unsigned long *args)
87 {
88 long *aregs = ®s->r0 - i;
89
90 BUG_ON(i > 5 || i + n > 6);
91
92 while (n--)
93 *aregs-- = *args++;
94 }
95
96 #endif
97