xref: /openbmc/linux/arch/nios2/mm/uaccess.c (revision 5ccc6af5)

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2009, Wind River Systems Inc
 * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
 */

#include <linux/export.h>
#include <linux/uaccess.h>

asm(".global	__copy_from_user\n"
	"   .type __copy_from_user, @function\n"
	"__copy_from_user:\n"
	"   movi  r2,7\n"
	"   mov   r3,r4\n"
	"   bge   r2,r6,1f\n"
	"   xor   r2,r4,r5\n"
	"   andi  r2,r2,3\n"
	"   movi  r7,3\n"
	"   beq   r2,zero,4f\n"
	"1: addi  r6,r6,-1\n"
	"   movi  r2,-1\n"
	"   beq   r6,r2,3f\n"
	"   mov   r7,r2\n"
	"2: ldbu  r2,0(r5)\n"
	"   addi  r6,r6,-1\n"
	"   addi  r5,r5,1\n"
	"   stb   r2,0(r3)\n"
	"   addi  r3,r3,1\n"
	"   bne   r6,r7,2b\n"
	"3:\n"
	"   addi  r2,r6,1\n"
	"   ret\n"
	"13:mov   r2,r6\n"
	"   ret\n"
	"4: andi  r2,r4,1\n"
	"   cmpeq r2,r2,zero\n"
	"   beq   r2,zero,7f\n"
	"5: andi  r2,r3,2\n"
	"   beq   r2,zero,6f\n"
	"9: ldhu  r2,0(r5)\n"
	"   addi  r6,r6,-2\n"
	"   addi  r5,r5,2\n"
	"   sth   r2,0(r3)\n"
	"   addi  r3,r3,2\n"
	"6: bge   r7,r6,1b\n"
	"10:ldw   r2,0(r5)\n"
	"   addi  r6,r6,-4\n"
	"   addi  r5,r5,4\n"
	"   stw   r2,0(r3)\n"
	"   addi  r3,r3,4\n"
	"   br    6b\n"
	"7: ldbu  r2,0(r5)\n"
	"   addi  r6,r6,-1\n"
	"   addi  r5,r5,1\n"
	"   addi  r3,r4,1\n"
	"   stb   r2,0(r4)\n"
	"   br    5b\n"
	".section __ex_table,\"a\"\n"
	".word 2b,3b\n"
	".word 9b,13b\n"
	".word 10b,13b\n"
	".word 7b,13b\n"
	".previous\n"
	);
EXPORT_SYMBOL(__copy_from_user);

asm(
	"   .global __copy_to_user\n"
	"   .type __copy_to_user, @function\n"
	"__copy_to_user:\n"
	"   movi  r2,7\n"
	"   mov   r3,r4\n"
	"   bge   r2,r6,1f\n"
	"   xor   r2,r4,r5\n"
	"   andi  r2,r2,3\n"
	"   movi  r7,3\n"
	"   beq   r2,zero,4f\n"
	/* Bail if we try to copy zero bytes  */
	"1: addi  r6,r6,-1\n"
	"   movi  r2,-1\n"
	"   beq   r6,r2,3f\n"
	/* Copy byte by byte for small copies and if src^dst != 0 */
	"   mov   r7,r2\n"
	"2: ldbu  r2,0(r5)\n"
	"   addi  r5,r5,1\n"
	"9: stb   r2,0(r3)\n"
	"   addi  r6,r6,-1\n"
	"   addi  r3,r3,1\n"
	"   bne   r6,r7,2b\n"
	"3: addi  r2,r6,1\n"
	"   ret\n"
	"13:mov   r2,r6\n"
	"   ret\n"
	/*  If 'to' is an odd address byte copy */
	"4: andi  r2,r4,1\n"
	"   cmpeq r2,r2,zero\n"
	"   beq   r2,zero,7f\n"
	/* If 'to' is not divideable by four copy halfwords */
	"5: andi  r2,r3,2\n"
	"   beq   r2,zero,6f\n"
	"   ldhu  r2,0(r5)\n"
	"   addi  r5,r5,2\n"
	"10:sth   r2,0(r3)\n"
	"   addi  r6,r6,-2\n"
	"   addi  r3,r3,2\n"
	/* Copy words */
	"6: bge   r7,r6,1b\n"
	"   ldw   r2,0(r5)\n"
	"   addi  r5,r5,4\n"
	"11:stw   r2,0(r3)\n"
	"   addi  r6,r6,-4\n"
	"   addi  r3,r3,4\n"
	"   br    6b\n"
	/* Copy remaining bytes */
	"7: ldbu  r2,0(r5)\n"
	"   addi  r5,r5,1\n"
	"   addi  r3,r4,1\n"
	"12: stb  r2,0(r4)\n"
	"   addi  r6,r6,-1\n"
	"   br    5b\n"
	".section __ex_table,\"a\"\n"
	".word 9b,3b\n"
	".word 10b,13b\n"
	".word 11b,13b\n"
	".word 12b,13b\n"
	".previous\n");
EXPORT_SYMBOL(__copy_to_user);

long strncpy_from_user(char *__to, const char __user *__from, long __len)
{
	int l = strnlen_user(__from, __len);
	int is_zt = 1;

	if (l > __len) {
		is_zt = 0;
		l = __len;
	}

	if (l == 0 || copy_from_user(__to, __from, l))
		return -EFAULT;

	if (is_zt)
		l--;
	return l;
}

long strnlen_user(const char __user *s, long n)
{
	long i;

	for (i = 0; i < n; i++) {
		char c;

		if (get_user(c, s + i) == -EFAULT)
			return 0;
		if (c == 0)
			return i + 1;
	}
	return n + 1;
}