1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
|
/*
* arch/xtensa/lib/strncpy_user.S
*
* 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.
*
* Returns: -EFAULT if exception before terminator, N if the entire
* buffer filled, else strlen.
*
* Copyright (C) 2002 Tensilica Inc.
*/
#include <variant/core.h>
#include <linux/errno.h>
/* Load or store instructions that may cause exceptions use the EX macro. */
#define EX(insn,reg1,reg2,offset,handler) \
9: insn reg1, reg2, offset; \
.section __ex_table, "a"; \
.word 9b, handler; \
.previous
/*
* char *__strncpy_user(char *dst, const char *src, size_t len)
*/
#ifdef __XTENSA_EB__
# define MASK0 0xff000000
# define MASK1 0x00ff0000
# define MASK2 0x0000ff00
# define MASK3 0x000000ff
#else
# define MASK0 0x000000ff
# define MASK1 0x0000ff00
# define MASK2 0x00ff0000
# define MASK3 0xff000000
#endif
# Register use
# a0/ return address
# a1/ stack pointer
# a2/ return value
# a3/ src
# a4/ len
# a5/ mask0
# a6/ mask1
# a7/ mask2
# a8/ mask3
# a9/ tmp
# a10/ tmp
# a11/ dst
# a12/ tmp
.text
.align 4
.global __strncpy_user
.type __strncpy_user,@function
__strncpy_user:
entry sp, 16 # minimal stack frame
# a2/ dst, a3/ src, a4/ len
mov a11, a2 # leave dst in return value register
beqz a4, .Lret # if len is zero
movi a5, MASK0 # mask for byte 0
movi a6, MASK1 # mask for byte 1
movi a7, MASK2 # mask for byte 2
movi a8, MASK3 # mask for byte 3
bbsi.l a3, 0, .Lsrc1mod2 # if only 8-bit aligned
bbsi.l a3, 1, .Lsrc2mod4 # if only 16-bit aligned
.Lsrcaligned: # return here when src is word-aligned
srli a12, a4, 2 # number of loop iterations with 4B per loop
movi a9, 3
bnone a11, a9, .Laligned
j .Ldstunaligned
.Lsrc1mod2: # src address is odd
EX(l8ui, a9, a3, 0, fixup_l) # get byte 0
addi a3, a3, 1 # advance src pointer
EX(s8i, a9, a11, 0, fixup_s) # store byte 0
beqz a9, .Lret # if byte 0 is zero
addi a11, a11, 1 # advance dst pointer
addi a4, a4, -1 # decrement len
beqz a4, .Lret # if len is zero
bbci.l a3, 1, .Lsrcaligned # if src is now word-aligned
.Lsrc2mod4: # src address is 2 mod 4
EX(l8ui, a9, a3, 0, fixup_l) # get byte 0
/* 1-cycle interlock */
EX(s8i, a9, a11, 0, fixup_s) # store byte 0
beqz a9, .Lret # if byte 0 is zero
addi a11, a11, 1 # advance dst pointer
addi a4, a4, -1 # decrement len
beqz a4, .Lret # if len is zero
EX(l8ui, a9, a3, 1, fixup_l) # get byte 0
addi a3, a3, 2 # advance src pointer
EX(s8i, a9, a11, 0, fixup_s) # store byte 0
beqz a9, .Lret # if byte 0 is zero
addi a11, a11, 1 # advance dst pointer
addi a4, a4, -1 # decrement len
bnez a4, .Lsrcaligned # if len is nonzero
.Lret:
sub a2, a11, a2 # compute strlen
retw
/*
* dst is word-aligned, src is word-aligned
*/
.align 4 # 1 mod 4 alignment for LOOPNEZ
.byte 0 # (0 mod 4 alignment for LBEG)
.Laligned:
#if XCHAL_HAVE_LOOPS
loopnez a12, .Loop1done
#else
beqz a12, .Loop1done
slli a12, a12, 2
add a12, a12, a11 # a12 = end of last 4B chunck
#endif
.Loop1:
EX(l32i, a9, a3, 0, fixup_l) # get word from src
addi a3, a3, 4 # advance src pointer
bnone a9, a5, .Lz0 # if byte 0 is zero
bnone a9, a6, .Lz1 # if byte 1 is zero
bnone a9, a7, .Lz2 # if byte 2 is zero
EX(s32i, a9, a11, 0, fixup_s) # store word to dst
bnone a9, a8, .Lz3 # if byte 3 is zero
addi a11, a11, 4 # advance dst pointer
#if !XCHAL_HAVE_LOOPS
blt a11, a12, .Loop1
#endif
.Loop1done:
bbci.l a4, 1, .L100
# copy 2 bytes
EX(l16ui, a9, a3, 0, fixup_l)
addi a3, a3, 2 # advance src pointer
#ifdef __XTENSA_EB__
bnone a9, a7, .Lz0 # if byte 2 is zero
bnone a9, a8, .Lz1 # if byte 3 is zero
#else
bnone a9, a5, .Lz0 # if byte 0 is zero
bnone a9, a6, .Lz1 # if byte 1 is zero
#endif
EX(s16i, a9, a11, 0, fixup_s)
addi a11, a11, 2 # advance dst pointer
.L100:
bbci.l a4, 0, .Lret
EX(l8ui, a9, a3, 0, fixup_l)
/* slot */
EX(s8i, a9, a11, 0, fixup_s)
beqz a9, .Lret # if byte is zero
addi a11, a11, 1-3 # advance dst ptr 1, but also cancel
# the effect of adding 3 in .Lz3 code
/* fall thru to .Lz3 and "retw" */
.Lz3: # byte 3 is zero
addi a11, a11, 3 # advance dst pointer
sub a2, a11, a2 # compute strlen
retw
.Lz0: # byte 0 is zero
#ifdef __XTENSA_EB__
movi a9, 0
#endif /* __XTENSA_EB__ */
EX(s8i, a9, a11, 0, fixup_s)
sub a2, a11, a2 # compute strlen
retw
.Lz1: # byte 1 is zero
#ifdef __XTENSA_EB__
extui a9, a9, 16, 16
#endif /* __XTENSA_EB__ */
EX(s16i, a9, a11, 0, fixup_s)
addi a11, a11, 1 # advance dst pointer
sub a2, a11, a2 # compute strlen
retw
.Lz2: # byte 2 is zero
#ifdef __XTENSA_EB__
extui a9, a9, 16, 16
#endif /* __XTENSA_EB__ */
EX(s16i, a9, a11, 0, fixup_s)
movi a9, 0
EX(s8i, a9, a11, 2, fixup_s)
addi a11, a11, 2 # advance dst pointer
sub a2, a11, a2 # compute strlen
retw
.align 4 # 1 mod 4 alignment for LOOPNEZ
.byte 0 # (0 mod 4 alignment for LBEG)
.Ldstunaligned:
/*
* for now just use byte copy loop
*/
#if XCHAL_HAVE_LOOPS
loopnez a4, .Lunalignedend
#else
beqz a4, .Lunalignedend
add a12, a11, a4 # a12 = ending address
#endif /* XCHAL_HAVE_LOOPS */
.Lnextbyte:
EX(l8ui, a9, a3, 0, fixup_l)
addi a3, a3, 1
EX(s8i, a9, a11, 0, fixup_s)
beqz a9, .Lunalignedend
addi a11, a11, 1
#if !XCHAL_HAVE_LOOPS
blt a11, a12, .Lnextbyte
#endif
.Lunalignedend:
sub a2, a11, a2 # compute strlen
retw
.section .fixup, "ax"
.align 4
/* For now, just return -EFAULT. Future implementations might
* like to clear remaining kernel space, like the fixup
* implementation in memset(). Thus, we differentiate between
* load/store fixups. */
fixup_s:
fixup_l:
movi a2, -EFAULT
retw
|
