1 /*
2 * arch/xtensa/lib/usercopy.S
3 *
4 * Copy to/from user space (derived from arch
5 *
6 * DO NOT COMBINE this function with <arch/xt
7 * It needs to remain separate and distinct.
8 * of the Xtensa link-time HAL, and those fil
9 * processor configuration. Patching the ker
10 * processor configuration includes replacing
11 * could lose the special functionality for a
12 * memory during such a patch. We sacrifice
13 * in favor to simplify code maintenance.
14 *
15 * This file is subject to the terms and cond
16 * Public License. See the file "COPYING" in
17 * this archive for more details.
18 *
19 * Copyright (C) 2002 Tensilica Inc.
20 */
21
22
23 /*
24 * size_t __xtensa_copy_user (void *dst, const
25 *
26 * The returned value is the number of bytes n
27 * is success.
28 *
29 * The general case algorithm is as follows:
30 * If the destination and source are both al
31 * do 16B chunks with a loop, and then fin
32 * 8B, 4B, 2B, and 1B copies conditional o
33 * If destination is aligned and source unal
34 * do the same, but use SRC to align the s
35 * If destination is unaligned, align it by
36 * copying 1B and 2B and then retest.
37 * This code tries to use fall-through brach
38 * case of aligned destinations (except fo
39 * the alignment label).
40 *
41 * Register use:
42 * a0/ return address
43 * a1/ stack pointer
44 * a2/ return value
45 * a3/ src
46 * a4/ length
47 * a5/ dst
48 * a6/ tmp
49 * a7/ tmp
50 * a8/ tmp
51 * a9/ tmp
52 * a10/ tmp
53 * a11/ original length
54 */
55
56 #include <linux/linkage.h>
57 #include <asm/asmmacro.h>
58 #include <asm/core.h>
59
60 .text
61 ENTRY(__xtensa_copy_user)
62
63 #if !XCHAL_HAVE_LOOPS && defined(__XTENSA_CALL
64 #define STACK_SIZE 4
65 #else
66 #define STACK_SIZE 0
67 #endif
68 abi_entry(STACK_SIZE)
69 # a2/ dst, a3/ src, a4/ len
70 mov a5, a2 # copy dst so
71 mov a11, a4 # preserve ori
72 .Lcommon:
73 bbsi.l a2, 0, .Ldst1mod2 # if dst is
74 bbsi.l a2, 1, .Ldst2mod4 # if dst is
75 .Ldstaligned: # return here from .Ldstunalig
76 srli a7, a4, 4 # number of lo
77 # per iteratio
78 movi a8, 3 # if source
79 bnone a3, a8, .Laligned # then use w
80 __ssa8 a3 # set shift am
81 bnez a4, .Lsrcunaligned
82 movi a2, 0 # return succe
83 abi_ret(STACK_SIZE)
84
85 /*
86 * Destination is unaligned
87 */
88
89 .Ldst1mod2: # dst is only byte aligned
90 bltui a4, 7, .Lbytecopy # do s
91
92 # copy 1 byte
93 EX(10f) l8ui a6, a3, 0
94 addi a3, a3, 1
95 EX(10f) s8i a6, a5, 0
96 addi a5, a5, 1
97 addi a4, a4, -1
98 bbci.l a5, 1, .Ldstaligned # if d
99 # retu
100 .Ldst2mod4: # dst 16-bit aligned
101 # copy 2 bytes
102 bltui a4, 6, .Lbytecopy # do s
103 EX(10f) l8ui a6, a3, 0
104 EX(10f) l8ui a7, a3, 1
105 addi a3, a3, 2
106 EX(10f) s8i a6, a5, 0
107 EX(10f) s8i a7, a5, 1
108 addi a5, a5, 2
109 addi a4, a4, -2
110 j .Ldstaligned # dst is now a
111
112 /*
113 * Byte by byte copy
114 */
115 .align 4
116 .byte 0 # 1 mod 4 alig
117 # (0 mod 4 ali
118 .Lbytecopy:
119 #if XCHAL_HAVE_LOOPS
120 loopnez a4, .Lbytecopydone
121 #else /* !XCHAL_HAVE_LOOPS */
122 beqz a4, .Lbytecopydone
123 add a7, a3, a4 # a7 = end add
124 #endif /* !XCHAL_HAVE_LOOPS */
125 .Lnextbyte:
126 EX(10f) l8ui a6, a3, 0
127 addi a3, a3, 1
128 EX(10f) s8i a6, a5, 0
129 addi a5, a5, 1
130 #if !XCHAL_HAVE_LOOPS
131 blt a3, a7, .Lnextbyte
132 #endif /* !XCHAL_HAVE_LOOPS */
133 .Lbytecopydone:
134 movi a2, 0 # return succe
135 abi_ret(STACK_SIZE)
136
137 /*
138 * Destination and source are word-aligned.
139 */
140 # copy 16 bytes per iteration for word
141 .align 4 # 1 mod 4 alig
142 .byte 0 # (0 mod 4 ali
143 .Laligned:
144 #if XCHAL_HAVE_LOOPS
145 loopnez a7, .Loop1done
146 #else /* !XCHAL_HAVE_LOOPS */
147 beqz a7, .Loop1done
148 slli a8, a7, 4
149 add a8, a8, a3 # a8 = end of
150 #endif /* !XCHAL_HAVE_LOOPS */
151 .Loop1:
152 EX(10f) l32i a6, a3, 0
153 EX(10f) l32i a7, a3, 4
154 EX(10f) s32i a6, a5, 0
155 EX(10f) l32i a6, a3, 8
156 EX(10f) s32i a7, a5, 4
157 EX(10f) l32i a7, a3, 12
158 EX(10f) s32i a6, a5, 8
159 addi a3, a3, 16
160 EX(10f) s32i a7, a5, 12
161 addi a5, a5, 16
162 #if !XCHAL_HAVE_LOOPS
163 blt a3, a8, .Loop1
164 #endif /* !XCHAL_HAVE_LOOPS */
165 .Loop1done:
166 bbci.l a4, 3, .L2
167 # copy 8 bytes
168 EX(10f) l32i a6, a3, 0
169 EX(10f) l32i a7, a3, 4
170 addi a3, a3, 8
171 EX(10f) s32i a6, a5, 0
172 EX(10f) s32i a7, a5, 4
173 addi a5, a5, 8
174 .L2:
175 bbci.l a4, 2, .L3
176 # copy 4 bytes
177 EX(10f) l32i a6, a3, 0
178 addi a3, a3, 4
179 EX(10f) s32i a6, a5, 0
180 addi a5, a5, 4
181 .L3:
182 bbci.l a4, 1, .L4
183 # copy 2 bytes
184 EX(10f) l16ui a6, a3, 0
185 addi a3, a3, 2
186 EX(10f) s16i a6, a5, 0
187 addi a5, a5, 2
188 .L4:
189 bbci.l a4, 0, .L5
190 # copy 1 byte
191 EX(10f) l8ui a6, a3, 0
192 EX(10f) s8i a6, a5, 0
193 .L5:
194 movi a2, 0 # return succe
195 abi_ret(STACK_SIZE)
196
197 /*
198 * Destination is aligned, Source is unaligned
199 */
200
201 .align 4
202 .byte 0 # 1 mod 4 alig
203 # (0 mod 4 ali
204 .Lsrcunaligned:
205 # copy 16 bytes per iteration for word
206 and a10, a3, a8 # save unalign
207 sub a3, a3, a10 # align a3 (to
208 EX(10f) l32i a6, a3, 0 # load first w
209 #if XCHAL_HAVE_LOOPS
210 loopnez a7, .Loop2done
211 #else /* !XCHAL_HAVE_LOOPS */
212 beqz a7, .Loop2done
213 #if defined(__XTENSA_CALL0_ABI__)
214 s32i a10, a1, 0
215 slli a10, a7, 4
216 add a10, a10, a3 # a10 = end of
217 #else
218 slli a12, a7, 4
219 add a12, a12, a3 # a12 = end of
220 #endif
221 #endif /* !XCHAL_HAVE_LOOPS */
222 .Loop2:
223 EX(10f) l32i a7, a3, 4
224 EX(10f) l32i a8, a3, 8
225 __src_b a6, a6, a7
226 EX(10f) s32i a6, a5, 0
227 EX(10f) l32i a9, a3, 12
228 __src_b a7, a7, a8
229 EX(10f) s32i a7, a5, 4
230 EX(10f) l32i a6, a3, 16
231 __src_b a8, a8, a9
232 EX(10f) s32i a8, a5, 8
233 addi a3, a3, 16
234 __src_b a9, a9, a6
235 EX(10f) s32i a9, a5, 12
236 addi a5, a5, 16
237 #if !XCHAL_HAVE_LOOPS
238 #if defined(__XTENSA_CALL0_ABI__)
239 blt a3, a10, .Loop2
240 l32i a10, a1, 0
241 #else
242 blt a3, a12, .Loop2
243 #endif
244 #endif /* !XCHAL_HAVE_LOOPS */
245 .Loop2done:
246 bbci.l a4, 3, .L12
247 # copy 8 bytes
248 EX(10f) l32i a7, a3, 4
249 EX(10f) l32i a8, a3, 8
250 __src_b a6, a6, a7
251 EX(10f) s32i a6, a5, 0
252 addi a3, a3, 8
253 __src_b a7, a7, a8
254 EX(10f) s32i a7, a5, 4
255 addi a5, a5, 8
256 mov a6, a8
257 .L12:
258 bbci.l a4, 2, .L13
259 # copy 4 bytes
260 EX(10f) l32i a7, a3, 4
261 addi a3, a3, 4
262 __src_b a6, a6, a7
263 EX(10f) s32i a6, a5, 0
264 addi a5, a5, 4
265 mov a6, a7
266 .L13:
267 add a3, a3, a10 # readjust a3
268 bbci.l a4, 1, .L14
269 # copy 2 bytes
270 EX(10f) l8ui a6, a3, 0
271 EX(10f) l8ui a7, a3, 1
272 addi a3, a3, 2
273 EX(10f) s8i a6, a5, 0
274 EX(10f) s8i a7, a5, 1
275 addi a5, a5, 2
276 .L14:
277 bbci.l a4, 0, .L15
278 # copy 1 byte
279 EX(10f) l8ui a6, a3, 0
280 EX(10f) s8i a6, a5, 0
281 .L15:
282 movi a2, 0 # return succe
283 abi_ret(STACK_SIZE)
284
285 ENDPROC(__xtensa_copy_user)
286 EXPORT_SYMBOL(__xtensa_copy_user)
287
288 .section .fixup, "ax"
289 .align 4
290
291 /* a2 = original dst; a5 = current dst; a11= o
292 * bytes_copied = a5 - a2
293 * retval = bytes_not_copied = original len -
294 * retval = a11 - (a5 - a2)
295 */
296
297
298 10:
299 sub a2, a5, a2 /* a2 <-- byte
300 sub a2, a11, a2 /* a2 <-- byte
301 abi_ret(STACK_SIZE)
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