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
25static inline long
26syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
27{
28	return regs->p0;
29}
30
31static inline void
32syscall_rollback(struct task_struct *task, struct pt_regs *regs)
33{
34	regs->p0 = regs->orig_p0;
35}
36
37static inline long
38syscall_get_error(struct task_struct *task, struct pt_regs *regs)
39{
40	return IS_ERR_VALUE(regs->r0) ? regs->r0 : 0;
41}
42
43static inline long
44syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
45{
46	return regs->r0;
47}
48
49static inline void
50syscall_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 */
66static inline void
67syscall_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 = &regs->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 */
84static inline void
85syscall_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 = &regs->r0 - i;
89
90	BUG_ON(i > 5 || i + n > 6);
91
92	while (n--)
93		*aregs-- = *args++;
94}
95
96#endif
97