strnlen_user.S (1439B)
1/* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (c) 1996, 1998, 1999, 2004 by Ralf Baechle 7 * Copyright (c) 1999 Silicon Graphics, Inc. 8 */ 9#include <asm/asm.h> 10#include <asm/asm-offsets.h> 11#include <asm/export.h> 12#include <asm/regdef.h> 13 14#define EX(insn,reg,addr,handler) \ 159: insn reg, addr; \ 16 .section __ex_table,"a"; \ 17 PTR_WD 9b, handler; \ 18 .previous 19 20/* 21 * Return the size of a string including the ending NUL character up to a 22 * maximum of a1 or 0 in case of error. 23 * 24 * Note: for performance reasons we deliberately accept that a user may 25 * make strlen_user and strnlen_user access the first few KSEG0 26 * bytes. There's nothing secret there. On 64-bit accessing beyond 27 * the maximum is a tad hairier ... 28 */ 29LEAF(__strnlen_user_asm) 30 move v0, a0 31 PTR_ADDU a1, a0 # stop pointer 321: 33#ifdef CONFIG_CPU_DADDI_WORKAROUNDS 34 .set noat 35 li AT, 1 36#endif 37 beq v0, a1, 1f # limit reached? 38#ifdef CONFIG_EVA 39 .set push 40 .set eva 41 EX(lbe, t0, (v0), .Lfault) 42 .set pop 43#else 44 EX(lb, t0, (v0), .Lfault) 45#endif 46 .set noreorder 47 bnez t0, 1b 481: 49#ifndef CONFIG_CPU_DADDI_WORKAROUNDS 50 PTR_ADDIU v0, 1 51#else 52 PTR_ADDU v0, AT 53 .set at 54#endif 55 .set reorder 56 PTR_SUBU v0, a0 57 jr ra 58 END(__strnlen_user_asm) 59 60.Lfault: 61 move v0, zero 62 jr ra 63 64 EXPORT_SYMBOL(__strnlen_user_asm)