syscall.h

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/*
 * 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;
}

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