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249ac17e CZ |
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 | ||
367b8112 | 14 | #include <variant/core.h> |
249ac17e CZ |
15 | #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) \ | |
20 | 9: 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 | */ | |
a0bb46ba CZ |
28 | |
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 | |
249ac17e CZ |
40 | |
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 | ||
a0bb46ba | 56 | .text |
249ac17e CZ |
57 | .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 | |
a0bb46ba CZ |
65 | 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 | |
249ac17e CZ |
69 | 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__ | |
c4c4594b | 169 | extui a9, a9, 16, 16 |
249ac17e CZ |
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__ | |
c4c4594b | 177 | extui a9, a9, 16, 16 |
249ac17e CZ |
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 | ||
221 | fixup_s: | |
222 | fixup_l: | |
223 | movi a2, -EFAULT | |
224 | retw | |
225 |