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Chris Zankel249ac172005-06-23 22:01:20 -07001/*
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
Chris Zankel173d6682006-12-10 02:18:48 -080014#include <asm/variant/core.h>
Chris Zankel249ac172005-06-23 22:01:20 -070015#include <linux/errno.h>
16
17/* Load or store instructions that may cause exceptions use the EX macro. */
18
19#define EX(insn,reg1,reg2,offset,handler) \
209: insn reg1, reg2, offset; \
21 .section __ex_table, "a"; \
22 .word 9b, handler; \
23 .previous
24
25/*
26 * char *__strncpy_user(char *dst, const char *src, size_t len)
27 */
Chris Zankela0bb46b2007-05-31 17:44:31 -070028
29#ifdef __XTENSA_EB__
30# define MASK0 0xff000000
31# define MASK1 0x00ff0000
32# define MASK2 0x0000ff00
33# define MASK3 0x000000ff
34#else
35# define MASK0 0x000000ff
36# define MASK1 0x0000ff00
37# define MASK2 0x00ff0000
38# define MASK3 0xff000000
39#endif
Chris Zankel249ac172005-06-23 22:01:20 -070040
41# Register use
42# a0/ return address
43# a1/ stack pointer
44# a2/ return value
45# a3/ src
46# a4/ len
47# a5/ mask0
48# a6/ mask1
49# a7/ mask2
50# a8/ mask3
51# a9/ tmp
52# a10/ tmp
53# a11/ dst
54# a12/ tmp
55
Chris Zankela0bb46b2007-05-31 17:44:31 -070056.text
Chris Zankel249ac172005-06-23 22:01:20 -070057.align 4
58.global __strncpy_user
59.type __strncpy_user,@function
60__strncpy_user:
61 entry sp, 16 # minimal stack frame
62 # a2/ dst, a3/ src, a4/ len
63 mov a11, a2 # leave dst in return value register
64 beqz a4, .Lret # if len is zero
Chris Zankela0bb46b2007-05-31 17:44:31 -070065 movi a5, MASK0 # mask for byte 0
66 movi a6, MASK1 # mask for byte 1
67 movi a7, MASK2 # mask for byte 2
68 movi a8, MASK3 # mask for byte 3
Chris Zankel249ac172005-06-23 22:01:20 -070069 bbsi.l a3, 0, .Lsrc1mod2 # if only 8-bit aligned
70 bbsi.l a3, 1, .Lsrc2mod4 # if only 16-bit aligned
71.Lsrcaligned: # return here when src is word-aligned
72 srli a12, a4, 2 # number of loop iterations with 4B per loop
73 movi a9, 3
74 bnone a11, a9, .Laligned
75 j .Ldstunaligned
76
77.Lsrc1mod2: # src address is odd
78 EX(l8ui, a9, a3, 0, fixup_l) # get byte 0
79 addi a3, a3, 1 # advance src pointer
80 EX(s8i, a9, a11, 0, fixup_s) # store byte 0
81 beqz a9, .Lret # if byte 0 is zero
82 addi a11, a11, 1 # advance dst pointer
83 addi a4, a4, -1 # decrement len
84 beqz a4, .Lret # if len is zero
85 bbci.l a3, 1, .Lsrcaligned # if src is now word-aligned
86
87.Lsrc2mod4: # src address is 2 mod 4
88 EX(l8ui, a9, a3, 0, fixup_l) # get byte 0
89 /* 1-cycle interlock */
90 EX(s8i, a9, a11, 0, fixup_s) # store byte 0
91 beqz a9, .Lret # if byte 0 is zero
92 addi a11, a11, 1 # advance dst pointer
93 addi a4, a4, -1 # decrement len
94 beqz a4, .Lret # if len is zero
95 EX(l8ui, a9, a3, 1, fixup_l) # get byte 0
96 addi a3, a3, 2 # advance src pointer
97 EX(s8i, a9, a11, 0, fixup_s) # store byte 0
98 beqz a9, .Lret # if byte 0 is zero
99 addi a11, a11, 1 # advance dst pointer
100 addi a4, a4, -1 # decrement len
101 bnez a4, .Lsrcaligned # if len is nonzero
102.Lret:
103 sub a2, a11, a2 # compute strlen
104 retw
105
106/*
107 * dst is word-aligned, src is word-aligned
108 */
109 .align 4 # 1 mod 4 alignment for LOOPNEZ
110 .byte 0 # (0 mod 4 alignment for LBEG)
111.Laligned:
112#if XCHAL_HAVE_LOOPS
113 loopnez a12, .Loop1done
114#else
115 beqz a12, .Loop1done
116 slli a12, a12, 2
117 add a12, a12, a11 # a12 = end of last 4B chunck
118#endif
119.Loop1:
120 EX(l32i, a9, a3, 0, fixup_l) # get word from src
121 addi a3, a3, 4 # advance src pointer
122 bnone a9, a5, .Lz0 # if byte 0 is zero
123 bnone a9, a6, .Lz1 # if byte 1 is zero
124 bnone a9, a7, .Lz2 # if byte 2 is zero
125 EX(s32i, a9, a11, 0, fixup_s) # store word to dst
126 bnone a9, a8, .Lz3 # if byte 3 is zero
127 addi a11, a11, 4 # advance dst pointer
128#if !XCHAL_HAVE_LOOPS
129 blt a11, a12, .Loop1
130#endif
131
132.Loop1done:
133 bbci.l a4, 1, .L100
134 # copy 2 bytes
135 EX(l16ui, a9, a3, 0, fixup_l)
136 addi a3, a3, 2 # advance src pointer
137#ifdef __XTENSA_EB__
138 bnone a9, a7, .Lz0 # if byte 2 is zero
139 bnone a9, a8, .Lz1 # if byte 3 is zero
140#else
141 bnone a9, a5, .Lz0 # if byte 0 is zero
142 bnone a9, a6, .Lz1 # if byte 1 is zero
143#endif
144 EX(s16i, a9, a11, 0, fixup_s)
145 addi a11, a11, 2 # advance dst pointer
146.L100:
147 bbci.l a4, 0, .Lret
148 EX(l8ui, a9, a3, 0, fixup_l)
149 /* slot */
150 EX(s8i, a9, a11, 0, fixup_s)
151 beqz a9, .Lret # if byte is zero
152 addi a11, a11, 1-3 # advance dst ptr 1, but also cancel
153 # the effect of adding 3 in .Lz3 code
154 /* fall thru to .Lz3 and "retw" */
155
156.Lz3: # byte 3 is zero
157 addi a11, a11, 3 # advance dst pointer
158 sub a2, a11, a2 # compute strlen
159 retw
160.Lz0: # byte 0 is zero
161#ifdef __XTENSA_EB__
162 movi a9, 0
163#endif /* __XTENSA_EB__ */
164 EX(s8i, a9, a11, 0, fixup_s)
165 sub a2, a11, a2 # compute strlen
166 retw
167.Lz1: # byte 1 is zero
168#ifdef __XTENSA_EB__
169 extui a9, a9, 16, 16
170#endif /* __XTENSA_EB__ */
171 EX(s16i, a9, a11, 0, fixup_s)
172 addi a11, a11, 1 # advance dst pointer
173 sub a2, a11, a2 # compute strlen
174 retw
175.Lz2: # byte 2 is zero
176#ifdef __XTENSA_EB__
177 extui a9, a9, 16, 16
178#endif /* __XTENSA_EB__ */
179 EX(s16i, a9, a11, 0, fixup_s)
180 movi a9, 0
181 EX(s8i, a9, a11, 2, fixup_s)
182 addi a11, a11, 2 # advance dst pointer
183 sub a2, a11, a2 # compute strlen
184 retw
185
186 .align 4 # 1 mod 4 alignment for LOOPNEZ
187 .byte 0 # (0 mod 4 alignment for LBEG)
188.Ldstunaligned:
189/*
190 * for now just use byte copy loop
191 */
192#if XCHAL_HAVE_LOOPS
193 loopnez a4, .Lunalignedend
194#else
195 beqz a4, .Lunalignedend
196 add a12, a11, a4 # a12 = ending address
197#endif /* XCHAL_HAVE_LOOPS */
198.Lnextbyte:
199 EX(l8ui, a9, a3, 0, fixup_l)
200 addi a3, a3, 1
201 EX(s8i, a9, a11, 0, fixup_s)
202 beqz a9, .Lunalignedend
203 addi a11, a11, 1
204#if !XCHAL_HAVE_LOOPS
205 blt a11, a12, .Lnextbyte
206#endif
207
208.Lunalignedend:
209 sub a2, a11, a2 # compute strlen
210 retw
211
212
213 .section .fixup, "ax"
214 .align 4
215
216 /* For now, just return -EFAULT. Future implementations might
217 * like to clear remaining kernel space, like the fixup
218 * implementation in memset(). Thus, we differentiate between
219 * load/store fixups. */
220
221fixup_s:
222fixup_l:
223 movi a2, -EFAULT
224 retw
225