1/* 2 * arch/xtensa/lib/strncpy_user.S 3 * 4 * This file is subject to the terms and conditions of the GNU General 5 * Public License. See the file "COPYING" in the main directory of 6 * this archive for more details. 7 * 8 * Returns: -EFAULT if exception before terminator, N if the entire 9 * buffer filled, else strlen. 10 * 11 * Copyright (C) 2002 Tensilica Inc. 12 */ 13 14#include <linux/errno.h> 15#include <linux/linkage.h> 16#include <asm/asmmacro.h> 17#include <asm/core.h> 18 19/* 20 * char *__strncpy_user(char *dst, const char *src, size_t len) 21 */ 22 23#ifdef __XTENSA_EB__ 24# define MASK0 0xff000000 25# define MASK1 0x00ff0000 26# define MASK2 0x0000ff00 27# define MASK3 0x000000ff 28#else 29# define MASK0 0x000000ff 30# define MASK1 0x0000ff00 31# define MASK2 0x00ff0000 32# define MASK3 0xff000000 33#endif 34 35# Register use 36# a0/ return address 37# a1/ stack pointer 38# a2/ return value 39# a3/ src 40# a4/ len 41# a5/ mask0 42# a6/ mask1 43# a7/ mask2 44# a8/ mask3 45# a9/ tmp 46# a10/ tmp 47# a11/ dst 48 49.text 50ENTRY(__strncpy_user) 51 52 abi_entry_default 53 # a2/ dst, a3/ src, a4/ len 54 mov a11, a2 # leave dst in return value register 55 beqz a4, .Lret # if len is zero 56 movi a5, MASK0 # mask for byte 0 57 movi a6, MASK1 # mask for byte 1 58 movi a7, MASK2 # mask for byte 2 59 movi a8, MASK3 # mask for byte 3 60 bbsi.l a3, 0, .Lsrc1mod2 # if only 8-bit aligned 61 bbsi.l a3, 1, .Lsrc2mod4 # if only 16-bit aligned 62.Lsrcaligned: # return here when src is word-aligned 63 srli a10, a4, 2 # number of loop iterations with 4B per loop 64 movi a9, 3 65 bnone a11, a9, .Laligned 66 j .Ldstunaligned 67 68.Lsrc1mod2: # src address is odd 69EX(11f) l8ui a9, a3, 0 # get byte 0 70 addi a3, a3, 1 # advance src pointer 71EX(10f) s8i a9, a11, 0 # store byte 0 72 beqz a9, .Lret # if byte 0 is zero 73 addi a11, a11, 1 # advance dst pointer 74 addi a4, a4, -1 # decrement len 75 beqz a4, .Lret # if len is zero 76 bbci.l a3, 1, .Lsrcaligned # if src is now word-aligned 77 78.Lsrc2mod4: # src address is 2 mod 4 79EX(11f) l8ui a9, a3, 0 # get byte 0 80 /* 1-cycle interlock */ 81EX(10f) s8i a9, a11, 0 # store byte 0 82 beqz a9, .Lret # if byte 0 is zero 83 addi a11, a11, 1 # advance dst pointer 84 addi a4, a4, -1 # decrement len 85 beqz a4, .Lret # if len is zero 86EX(11f) l8ui a9, a3, 1 # get byte 0 87 addi a3, a3, 2 # advance src pointer 88EX(10f) s8i a9, a11, 0 # store byte 0 89 beqz a9, .Lret # if byte 0 is zero 90 addi a11, a11, 1 # advance dst pointer 91 addi a4, a4, -1 # decrement len 92 bnez a4, .Lsrcaligned # if len is nonzero 93.Lret: 94 sub a2, a11, a2 # compute strlen 95 abi_ret_default 96 97/* 98 * dst is word-aligned, src is word-aligned 99 */ 100 .align 4 # 1 mod 4 alignment for LOOPNEZ 101 .byte 0 # (0 mod 4 alignment for LBEG) 102.Laligned: 103#if XCHAL_HAVE_LOOPS 104 loopnez a10, .Loop1done 105#else 106 beqz a10, .Loop1done 107 slli a10, a10, 2 108 add a10, a10, a11 # a10 = end of last 4B chunck 109#endif 110.Loop1: 111EX(11f) l32i a9, a3, 0 # get word from src 112 addi a3, a3, 4 # advance src pointer 113 bnone a9, a5, .Lz0 # if byte 0 is zero 114 bnone a9, a6, .Lz1 # if byte 1 is zero 115 bnone a9, a7, .Lz2 # if byte 2 is zero 116EX(10f) s32i a9, a11, 0 # store word to dst 117 bnone a9, a8, .Lz3 # if byte 3 is zero 118 addi a11, a11, 4 # advance dst pointer 119#if !XCHAL_HAVE_LOOPS 120 blt a11, a10, .Loop1 121#endif 122 123.Loop1done: 124 bbci.l a4, 1, .L100 125 # copy 2 bytes 126EX(11f) l16ui a9, a3, 0 127 addi a3, a3, 2 # advance src pointer 128#ifdef __XTENSA_EB__ 129 bnone a9, a7, .Lz0 # if byte 2 is zero 130 bnone a9, a8, .Lz1 # if byte 3 is zero 131#else 132 bnone a9, a5, .Lz0 # if byte 0 is zero 133 bnone a9, a6, .Lz1 # if byte 1 is zero 134#endif 135EX(10f) s16i a9, a11, 0 136 addi a11, a11, 2 # advance dst pointer 137.L100: 138 bbci.l a4, 0, .Lret 139EX(11f) l8ui a9, a3, 0 140 /* slot */ 141EX(10f) s8i a9, a11, 0 142 beqz a9, .Lret # if byte is zero 143 addi a11, a11, 1-3 # advance dst ptr 1, but also cancel 144 # the effect of adding 3 in .Lz3 code 145 /* fall thru to .Lz3 and "retw" */ 146 147.Lz3: # byte 3 is zero 148 addi a11, a11, 3 # advance dst pointer 149 sub a2, a11, a2 # compute strlen 150 abi_ret_default 151.Lz0: # byte 0 is zero 152#ifdef __XTENSA_EB__ 153 movi a9, 0 154#endif /* __XTENSA_EB__ */ 155EX(10f) s8i a9, a11, 0 156 sub a2, a11, a2 # compute strlen 157 abi_ret_default 158.Lz1: # byte 1 is zero 159#ifdef __XTENSA_EB__ 160 extui a9, a9, 16, 16 161#endif /* __XTENSA_EB__ */ 162EX(10f) s16i a9, a11, 0 163 addi a11, a11, 1 # advance dst pointer 164 sub a2, a11, a2 # compute strlen 165 abi_ret_default 166.Lz2: # byte 2 is zero 167#ifdef __XTENSA_EB__ 168 extui a9, a9, 16, 16 169#endif /* __XTENSA_EB__ */ 170EX(10f) s16i a9, a11, 0 171 movi a9, 0 172EX(10f) s8i a9, a11, 2 173 addi a11, a11, 2 # advance dst pointer 174 sub a2, a11, a2 # compute strlen 175 abi_ret_default 176 177 .align 4 # 1 mod 4 alignment for LOOPNEZ 178 .byte 0 # (0 mod 4 alignment for LBEG) 179.Ldstunaligned: 180/* 181 * for now just use byte copy loop 182 */ 183#if XCHAL_HAVE_LOOPS 184 loopnez a4, .Lunalignedend 185#else 186 beqz a4, .Lunalignedend 187 add a10, a11, a4 # a10 = ending address 188#endif /* XCHAL_HAVE_LOOPS */ 189.Lnextbyte: 190EX(11f) l8ui a9, a3, 0 191 addi a3, a3, 1 192EX(10f) s8i a9, a11, 0 193 beqz a9, .Lunalignedend 194 addi a11, a11, 1 195#if !XCHAL_HAVE_LOOPS 196 blt a11, a10, .Lnextbyte 197#endif 198 199.Lunalignedend: 200 sub a2, a11, a2 # compute strlen 201 abi_ret_default 202 203ENDPROC(__strncpy_user) 204 205 .section .fixup, "ax" 206 .align 4 207 208 /* For now, just return -EFAULT. Future implementations might 209 * like to clear remaining kernel space, like the fixup 210 * implementation in memset(). Thus, we differentiate between 211 * load/store fixups. */ 212 21310: 21411: 215 movi a2, -EFAULT 216 abi_ret_default 217