/* syscall parameter access functions
*
* Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
* Written by David Howells ([email protected])
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/

#ifndef _ASM_SYSCALL_H
#define _ASM_SYSCALL_H

#include <linux/err.h>
#include <asm/ptrace.h>

/*
* Get the system call number or -1
*/
static inline long syscall_get_nr(struct task_struct *task,
struct pt_regs *regs)
{
return regs->syscallno;
}

/*
* Restore the clobbered GR8 register
* (1st syscall arg was overwritten with syscall return or error)
*/
static inline void syscall_rollback(struct task_struct *task,
struct pt_regs *regs)
{
regs->gr8 = regs->orig_gr8;
}

/*
* See if the syscall return value is an error, returning it if it is and 0 if
* not
*/
static inline long syscall_get_error(struct task_struct *task,
struct pt_regs *regs)
{
return IS_ERR_VALUE(regs->gr8) ? regs->gr8 : 0;
}

/*
* Get the syscall return value
*/
static inline long syscall_get_return_value(struct task_struct *task,
struct pt_regs *regs)
{
return regs->gr8;
}

/*
* Set the syscall return value
*/
static inline void syscall_set_return_value(struct task_struct *task,
struct pt_regs *regs,
int error, long val)
{
if (error)
regs->gr8 = -error;
else
regs->gr8 = val;
}

/*
* Retrieve the system call arguments
*/
static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
unsigned int i, unsigned int n,
unsigned long *args)
{
/*
* Do this simply for now. If we need to start supporting
* fetching arguments from arbitrary indices, this will need some
* extra logic. Presently there are no in-tree users that depend
* on this behaviour.
*/
BUG_ON(i);

/* Argument pattern is: GR8, GR9, GR10, GR11, GR12, GR13 */
switch (n) {
case 6: args[5] = regs->gr13;
case 5: args[4] = regs->gr12;
case 4: args[3] = regs->gr11;
case 3: args[2] = regs->gr10;
case 2: args[1] = regs->gr9;
case 1: args[0] = regs->gr8;
break;
default:
BUG();
}
}

/*
* Alter the system call arguments
*/
static inline void syscall_set_arguments(struct task_struct *task,
struct pt_regs *regs,
unsigned int i, unsigned int n,
const unsigned long *args)
{
/* Same note as above applies */
BUG_ON(i);

switch (n) {
case 6: regs->gr13 = args[5];
case 5: regs->gr12 = args[4];
case 4: regs->gr11 = args[3];
case 3: regs->gr10 = args[2];
case 2: regs->gr9 = args[1];
case 1: regs->gr8 = args[0];
break;
default:
BUG();
}
}

#endif /* _ASM_SYSCALL_H */