why sys_mmap2 not use struct mmap_arg_struct

[Bao Zhao <baozhaolinuxer@xxxxxxxxx>]

The following code excerpt form sys_i386.c.

The  parameter  numbers of system call sys_mmap2 is six. So passing these parameters should use a
memory block  like old_mmap.

ULK 2ND SAID
"However, system calls that have more than six parameters exist. In such cases, a single register
is used to point to a memory area in the process address space that contains the parameter
values."

why does sys_mmap2  not follow the rule?

Thanks!
        
Bao Zhao


asmlinkage long sys_mmap2(unsigned long addr, unsigned long len,
	unsigned long prot, unsigned long flags,
	unsigned long fd, unsigned long pgoff)
{
	return do_mmap2(addr, len, prot, flags, fd, pgoff);
}

/*
 * Perform the select(nd, in, out, ex, tv) and mmap() system
 * calls. Linux/i386 didn't use to be able to handle more than
 * 4 system call parameters, so these system calls used a memory
 * block for parameter passing..
 */

struct mmap_arg_struct {
	unsigned long addr;
	unsigned long len;
	unsigned long prot;
	unsigned long flags;
	unsigned long fd;
	unsigned long offset;
};

asmlinkage int old_mmap(struct mmap_arg_struct __user *arg)
{
	struct mmap_arg_struct a;
	int err = -EFAULT;

	if (copy_from_user(&a, arg, sizeof(a)))
		goto out;

	err = -EINVAL;
	if (a.offset & ~PAGE_MASK)
		goto out;

	err = do_mmap2(a.addr, a.len, a.prot, a.flags, a.fd, a.offset >> PAGE_SHIFT);
out:
	return err;
}


		
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