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sys_arm.c

/*
 *  linux/arch/arm/kernel/sys_arm.c
 *
 *  Copyright (C) People who wrote linux/arch/i386/kernel/sys_i386.c
 *  Copyright (C) 1995, 1996 Russell King.
 *
 * 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 file contains various random system calls that
 *  have a non-standard calling sequence on the Linux/arm
 *  platform.
 */
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/sem.h>
#include <linux/msg.h>
#include <linux/shm.h>
#include <linux/stat.h>
#include <linux/syscalls.h>
#include <linux/mman.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/ipc.h>
#include <linux/uaccess.h>
#include <linux/slab.h>

/* Fork a new task - this creates a new program thread.
 * This is called indirectly via a small wrapper
 */
asmlinkage int sys_fork(struct pt_regs *regs)
{
#ifdef CONFIG_MMU
      return do_fork(SIGCHLD, regs->ARM_sp, regs, 0, NULL, NULL);
#else
      /* can not support in nommu mode */
      return(-EINVAL);
#endif
}

/* Clone a task - this clones the calling program thread.
 * This is called indirectly via a small wrapper
 */
asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
                   int __user *parent_tidptr, int tls_val,
                   int __user *child_tidptr, struct pt_regs *regs)
{
      if (!newsp)
            newsp = regs->ARM_sp;

      return do_fork(clone_flags, newsp, regs, 0, parent_tidptr, child_tidptr);
}

asmlinkage int sys_vfork(struct pt_regs *regs)
{
      return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->ARM_sp, regs, 0, NULL, NULL);
}

/* sys_execve() executes a new program.
 * This is called indirectly via a small wrapper
 */
asmlinkage int sys_execve(const char __user *filenamei,
                    const char __user *const __user *argv,
                    const char __user *const __user *envp, struct pt_regs *regs)
{
      int error;
      char * filename;

      filename = getname(filenamei);
      error = PTR_ERR(filename);
      if (IS_ERR(filename))
            goto out;
      error = do_execve(filename, argv, envp, regs);
      putname(filename);
out:
      return error;
}

int kernel_execve(const char *filename,
              const char *const argv[],
              const char *const envp[])
{
      struct pt_regs regs;
      int ret;

      memset(&regs, 0, sizeof(struct pt_regs));
      ret = do_execve(filename,
                  (const char __user *const __user *)argv,
                  (const char __user *const __user *)envp, &regs);
      if (ret < 0)
            goto out;

      /*
       * Save argc to the register structure for userspace.
       */
      regs.ARM_r0 = ret;

      /*
       * We were successful.  We won't be returning to our caller, but
       * instead to user space by manipulating the kernel stack.
       */
      asm(  "add  r0, %0, %1\n\t"
            "mov  r1, %2\n\t"
            "mov  r2, %3\n\t"
            "bl   memmove\n\t"      /* copy regs to top of stack */
            "mov  r8, #0\n\t" /* not a syscall */
            "mov  r9, %0\n\t" /* thread structure */
            "mov  sp, r0\n\t" /* reposition stack pointer */
            "b    ret_to_user"
            :
            : "r" (current_thread_info()),
              "Ir" (THREAD_START_SP - sizeof(regs)),
              "r" (&regs),
              "Ir" (sizeof(regs))
            : "r0", "r1", "r2", "r3", "ip", "lr", "memory");

 out:
      return ret;
}
EXPORT_SYMBOL(kernel_execve);

/*
 * Since loff_t is a 64 bit type we avoid a lot of ABI hassle
 * with a different argument ordering.
 */
asmlinkage long sys_arm_fadvise64_64(int fd, int advice,
                             loff_t offset, loff_t len)
{
      return sys_fadvise64_64(fd, offset, len, advice);
}

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