arch/blackfin/include/asm/syscall.h

/*
 * Magic syscall break down functions
 *
 * Copyright 2010 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#ifndef __ASM_BLACKFIN_SYSCALL_H__
#define __ASM_BLACKFIN_SYSCALL_H__

/*
 * Blackfin syscalls are simple:
 *	enter:
 *		p0: syscall number
 *		r{0,1,2,3,4,5}: syscall args 0,1,2,3,4,5
 *	exit:
 *		r0: return/error value
 */

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

static inline long
syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
{
	return regs->p0;
}

static inline void
syscall_rollback(struct task_struct *task, struct pt_regs *regs)
{
	regs->p0 = regs->orig_p0;
}

static inline long
syscall_get_error(struct task_struct *task, struct pt_regs *regs)
{
	return IS_ERR_VALUE(regs->r0) ? regs->r0 : 0;
}

static inline long
syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
{
	return regs->r0;
}

static inline void
syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
                         int error, long val)
{
	regs->r0 = error ? -error : val;
}

/**
 *	syscall_get_arguments()
 *	@task:   unused
 *	@regs:   the register layout to extract syscall arguments from
 *	@i:      first syscall argument to extract
 *	@n:      number of syscall arguments to extract
 *	@args:   array to return the syscall arguments in
 *
 * args[0] gets i'th argument, args[n - 1] gets the i+n-1'th argument
 */
static inline void
syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
                      unsigned int i, unsigned int n, unsigned long *args)
{
	/*
	 * Assume the ptrace layout doesn't change -- r5 is first in memory,
	 * then r4, ..., then r0.  So we simply reverse the ptrace register
	 * array in memory to store into the args array.
	 */
	long *aregs = &regs->r0 - i;

	BUG_ON(i > 5 || i + n > 6);

	while (n--)
		*args++ = *aregs--;
}

/* See syscall_get_arguments() comments */
static inline void
syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
                      unsigned int i, unsigned int n, const unsigned long *args)
{
	long *aregs = &regs->r0 - i;

	BUG_ON(i > 5 || i + n > 6);

	while (n--)
		*aregs-- = *args++;
}

#endif