usercopy.c

xenomai 很好的linux实时补丁

/* 
 * Lifted from linux/arch/i386/lib/usercopy.c, only to get rid of the
 * damned might_sleep() check, so that we can call this routine in
 * atomic context, provided the source memory is always committed and
 * locked.
 *
 * Copyright 1997 Andi Kleen <[e-mail]>
 * Copyright 1997 Linus Torvalds
 *
 * Xenomai is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, Inc., 675 Mass Ave,
 * Cambridge MA 02139, USA.
 */

#include <linux/config.h>
#include <linux/module.h>
#include <asm/uaccess.h>

#define __do_strncpy_from_user(dst,src,count,res)			   \
do {									   \
	int __d0, __d1, __d2;						   \
	__asm__ __volatile__(						   \
		"	testl %1,%1\n"					   \
		"	jz 2f\n"					   \
		"0:	lodsb\n"					   \
		"	stosb\n"					   \
		"	testb %%al,%%al\n"				   \
		"	jz 1f\n"					   \
		"	decl %1\n"					   \
		"	jnz 0b\n"					   \
		"1:	subl %1,%0\n"					   \
		"2:\n"							   \
		".section .fixup,\"ax\"\n"				   \
		"3:	movl %5,%0\n"					   \
		"	jmp 2b\n"					   \
		".previous\n"						   \
		".section __ex_table,\"a\"\n"				   \
		"	.align 4\n"					   \
		"	.long 0b,3b\n"					   \
		".previous"						   \
		: "=d"(res), "=c"(count), "=&a" (__d0), "=&S" (__d1),	   \
		  "=&D" (__d2)						   \
		: "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
		: "memory");						   \
} while (0)

long rthal_strncpy_from_user(char *dst, const char __user *src, long count)
{
	long res;
	__do_strncpy_from_user(dst, src, count, res);
	return res;
}

EXPORT_SYMBOL(rthal_strncpy_from_user);