syscall.h

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/*
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef __ASM_SYSCALL_H
#define __ASM_SYSCALL_H

#include <linux/err.h>


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

static inline void syscall_rollback(struct task_struct *task,
                    struct pt_regs *regs)
{
    regs->regs[0] = regs->orig_x0;
}


static inline long syscall_get_error(struct task_struct *task,
                     struct pt_regs *regs)
{
    unsigned long error = regs->regs[0];
    return IS_ERR_VALUE(error) ? error : 0;
}

static inline long syscall_get_return_value(struct task_struct *task,
                        struct pt_regs *regs)
{
    return regs->regs[0];
}

static inline void syscall_set_return_value(struct task_struct *task,
                        struct pt_regs *regs,
                        int error, long val)
{
    regs->regs[0] = (long) error ? error : val;
}

#define SYSCALL_MAX_ARGS 6

static inline void syscall_get_arguments(struct task_struct *task,
                     struct pt_regs *regs,
                     unsigned int i, unsigned int n,
                     unsigned long *args)
{
    if (i + n > SYSCALL_MAX_ARGS) {
        unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
        unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
        pr_warning("%s called with max args %d, handling only %d\n",
               __func__, i + n, SYSCALL_MAX_ARGS);
        memset(args_bad, 0, n_bad * sizeof(args[0]));
    }

    if (i == 0) {
        args[0] = regs->orig_x0;
        args++;
        i++;
        n--;
    }

    memcpy(args, &regs->regs[i], n * sizeof(args[0]));
}

static inline void syscall_set_arguments(struct task_struct *task,
                     struct pt_regs *regs,
                     unsigned int i, unsigned int n,
                     const unsigned long *args)
{
    if (i + n > SYSCALL_MAX_ARGS) {
        pr_warning("%s called with max args %d, handling only %d\n",
               __func__, i + n, SYSCALL_MAX_ARGS);
        n = SYSCALL_MAX_ARGS - i;
    }

    if (i == 0) {
        regs->orig_x0 = args[0];
        args++;
        i++;
        n--;
    }

    memcpy(&regs->regs[i], args, n * sizeof(args[0]));
}

#endif  /* __ASM_SYSCALL_H */