arch/arm/lib/copy_template.S

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  *  linux/arch/arm/lib/copy_template.s
   4  *
   5  *  Code template for optimized memory copy functions
   6  *
   7  *  Author:     Nicolas Pitre
   8  *  Created:    Sep 28, 2005
   9  *  Copyright:  MontaVista Software, Inc.
  10  */
  11
  12 /*
  13  * Theory of operation
  14  * -------------------
  15  *
  16  * This file provides the core code for a forward memory copy used in
  17  * the implementation of memcopy(), copy_to_user() and copy_from_user().
  18  *
  19  * The including file must define the following accessor macros
  20  * according to the need of the given function:
  21  *
  22  * ldr1w ptr reg abort
  23  *
  24  *      This loads one word from 'ptr', stores it in 'reg' and increments
  25  *      'ptr' to the next word. The 'abort' argument is used for fixup tables.
  26  *
  27  * ldr4w ptr reg1 reg2 reg3 reg4 abort
  28  * ldr8w ptr, reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
  29  *
  30  *      This loads four or eight words starting from 'ptr', stores them
  31  *      in provided registers and increments 'ptr' past those words.
  32  *      The'abort' argument is used for fixup tables.
  33  *
  34  * ldr1b ptr reg cond abort
  35  *
  36  *      Similar to ldr1w, but it loads a byte and increments 'ptr' one byte.
  37  *      It also must apply the condition code if provided, otherwise the
  38  *      "al" condition is assumed by default.
  39  *
  40  * str1w ptr reg abort
  41  * str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
  42  * str1b ptr reg cond abort
  43  *
  44  *      Same as their ldr* counterparts, but data is stored to 'ptr' location
  45  *      rather than being loaded.
  46  *
  47  * enter reg1 reg2
  48  *
  49  *      Preserve the provided registers on the stack plus any additional
  50  *      data as needed by the implementation including this code. Called
  51  *      upon code entry.
  52  *
  53  * usave reg1 reg2
  54  *
  55  *      Unwind annotation macro is corresponding for 'enter' macro.
  56  *      It tell unwinder that preserved some provided registers on the stack
  57  *      and additional data by a prior 'enter' macro.
  58  *
  59  * exit reg1 reg2
  60  *
  61  *      Restore registers with the values previously saved with the
  62  *      'preserv' macro. Called upon code termination.
  63  *
  64  * LDR1W_SHIFT
  65  * STR1W_SHIFT
  66  *
  67  *      Correction to be applied to the "ip" register when branching into
  68  *      the ldr1w or str1w instructions (some of these macros may expand to
  69  *      than one 32bit instruction in Thumb-2)
  70  */
  71
  72
  73         UNWIND( .fnstart                        )
  74                 enter   r4, lr
  75         UNWIND( .fnend                          )
  76
  77         UNWIND( .fnstart                        )
  78                 usave   r4, lr                    @ in first stmdb block
  79
  80                 subs    r2, r2, #4
  81                 blt     8f
  82                 ands    ip, r0, #3
  83         PLD(    pld     [r1, #0]                )
  84                 bne     9f
  85                 ands    ip, r1, #3
  86                 bne     10f
  87
  88 1:              subs    r2, r2, #(28)
  89                 stmfd   sp!, {r5 - r8}
  90         UNWIND( .fnend                          )
  91
  92         UNWIND( .fnstart                        )
  93                 usave   r4, lr
  94         UNWIND( .save   {r5 - r8}               ) @ in second stmfd block
  95                 blt     5f
  96
  97         CALGN(  ands    ip, r0, #31             )
  98         CALGN(  rsb     r3, ip, #32             )
  99         CALGN(  sbcsne  r4, r3, r2              )  @ C is always set here
 100         CALGN(  bcs     2f                      )
 101         CALGN(  adr     r4, 6f                  )
 102         CALGN(  subs    r2, r2, r3              )  @ C gets set
 103         CALGN(  add     pc, r4, ip              )
 104
 105         PLD(    pld     [r1, #0]                )
 106 2:      PLD(    subs    r2, r2, #96             )
 107         PLD(    pld     [r1, #28]               )
 108         PLD(    blt     4f                      )
 109         PLD(    pld     [r1, #60]               )
 110         PLD(    pld     [r1, #92]               )
 111
 112 3:      PLD(    pld     [r1, #124]              )
 113 4:              ldr8w   r1, r3, r4, r5, r6, r7, r8, ip, lr, abort=20f
 114                 subs    r2, r2, #32
 115                 str8w   r0, r3, r4, r5, r6, r7, r8, ip, lr, abort=20f
 116                 bge     3b
 117         PLD(    cmn     r2, #96                 )
 118         PLD(    bge     4b                      )
 119
 120 5:              ands    ip, r2, #28
 121                 rsb     ip, ip, #32
 122 #if LDR1W_SHIFT > 0
 123                 lsl     ip, ip, #LDR1W_SHIFT
 124 #endif
 125                 addne   pc, pc, ip              @ C is always clear here
 126                 b       7f
 127 6:
 128                 .rept   (1 << LDR1W_SHIFT)
 129                 W(nop)
 130                 .endr
 131                 ldr1w   r1, r3, abort=20f
 132                 ldr1w   r1, r4, abort=20f
 133                 ldr1w   r1, r5, abort=20f
 134                 ldr1w   r1, r6, abort=20f
 135                 ldr1w   r1, r7, abort=20f
 136                 ldr1w   r1, r8, abort=20f
 137                 ldr1w   r1, lr, abort=20f
 138
 139 #if LDR1W_SHIFT < STR1W_SHIFT
 140                 lsl     ip, ip, #STR1W_SHIFT - LDR1W_SHIFT
 141 #elif LDR1W_SHIFT > STR1W_SHIFT
 142                 lsr     ip, ip, #LDR1W_SHIFT - STR1W_SHIFT
 143 #endif
 144                 add     pc, pc, ip
 145                 nop
 146                 .rept   (1 << STR1W_SHIFT)
 147                 W(nop)
 148                 .endr
 149                 str1w   r0, r3, abort=20f
 150                 str1w   r0, r4, abort=20f
 151                 str1w   r0, r5, abort=20f
 152                 str1w   r0, r6, abort=20f
 153                 str1w   r0, r7, abort=20f
 154                 str1w   r0, r8, abort=20f
 155                 str1w   r0, lr, abort=20f
 156
 157         CALGN(  bcs     2b                      )
 158
 159 7:              ldmfd   sp!, {r5 - r8}
 160         UNWIND( .fnend                          ) @ end of second stmfd block
 161
 162         UNWIND( .fnstart                        )
 163                 usave   r4, lr                    @ still in first stmdb block
 164 8:              movs    r2, r2, lsl #31
 165                 ldr1b   r1, r3, ne, abort=21f
 166                 ldr1b   r1, r4, cs, abort=21f
 167                 ldr1b   r1, ip, cs, abort=21f
 168                 str1b   r0, r3, ne, abort=21f
 169                 str1b   r0, r4, cs, abort=21f
 170                 str1b   r0, ip, cs, abort=21f
 171
 172                 exit    r4, pc
 173
 174 9:              rsb     ip, ip, #4
 175                 cmp     ip, #2
 176                 ldr1b   r1, r3, gt, abort=21f
 177                 ldr1b   r1, r4, ge, abort=21f
 178                 ldr1b   r1, lr, abort=21f
 179                 str1b   r0, r3, gt, abort=21f
 180                 str1b   r0, r4, ge, abort=21f
 181                 subs    r2, r2, ip
 182                 str1b   r0, lr, abort=21f
 183                 blt     8b
 184                 ands    ip, r1, #3
 185                 beq     1b
 186
 187 10:             bic     r1, r1, #3
 188                 cmp     ip, #2
 189                 ldr1w   r1, lr, abort=21f
 190                 beq     17f
 191                 bgt     18f
 192         UNWIND( .fnend                          )
 193
 194
 195                 .macro  forward_copy_shift pull push
 196
 197         UNWIND( .fnstart                        )
 198                 usave   r4, lr                    @ still in first stmdb block
 199                 subs    r2, r2, #28
 200                 blt     14f
 201
 202         CALGN(  ands    ip, r0, #31             )
 203         CALGN(  rsb     ip, ip, #32             )
 204         CALGN(  sbcsne  r4, ip, r2              )  @ C is always set here
 205         CALGN(  subcc   r2, r2, ip              )
 206         CALGN(  bcc     15f                     )
 207
 208 11:             stmfd   sp!, {r5 - r9}
 209         UNWIND( .fnend                          )
 210
 211         UNWIND( .fnstart                        )
 212                 usave   r4, lr
 213         UNWIND( .save   {r5 - r9}               ) @ in new second stmfd block
 214         PLD(    pld     [r1, #0]                )
 215         PLD(    subs    r2, r2, #96             )
 216         PLD(    pld     [r1, #28]               )
 217         PLD(    blt     13f                     )
 218         PLD(    pld     [r1, #60]               )
 219         PLD(    pld     [r1, #92]               )
 220
 221 12:     PLD(    pld     [r1, #124]              )
 222 13:             ldr4w   r1, r4, r5, r6, r7, abort=19f
 223                 mov     r3, lr, lspull #\pull
 224                 subs    r2, r2, #32
 225                 ldr4w   r1, r8, r9, ip, lr, abort=19f
 226                 orr     r3, r3, r4, lspush #\push
 227                 mov     r4, r4, lspull #\pull
 228                 orr     r4, r4, r5, lspush #\push
 229                 mov     r5, r5, lspull #\pull
 230                 orr     r5, r5, r6, lspush #\push
 231                 mov     r6, r6, lspull #\pull
 232                 orr     r6, r6, r7, lspush #\push
 233                 mov     r7, r7, lspull #\pull
 234                 orr     r7, r7, r8, lspush #\push
 235                 mov     r8, r8, lspull #\pull
 236                 orr     r8, r8, r9, lspush #\push
 237                 mov     r9, r9, lspull #\pull
 238                 orr     r9, r9, ip, lspush #\push
 239                 mov     ip, ip, lspull #\pull
 240                 orr     ip, ip, lr, lspush #\push
 241                 str8w   r0, r3, r4, r5, r6, r7, r8, r9, ip, abort=19f
 242                 bge     12b
 243         PLD(    cmn     r2, #96                 )
 244         PLD(    bge     13b                     )
 245
 246                 ldmfd   sp!, {r5 - r9}
 247         UNWIND( .fnend                          ) @ end of the second stmfd block
 248
 249         UNWIND( .fnstart                        )
 250                 usave   r4, lr                    @ still in first stmdb block
 251 14:             ands    ip, r2, #28
 252                 beq     16f
 253
 254 15:             mov     r3, lr, lspull #\pull
 255                 ldr1w   r1, lr, abort=21f
 256                 subs    ip, ip, #4
 257                 orr     r3, r3, lr, lspush #\push
 258                 str1w   r0, r3, abort=21f
 259                 bgt     15b
 260         CALGN(  cmp     r2, #0                  )
 261         CALGN(  bge     11b                     )
 262
 263 16:             sub     r1, r1, #(\push / 8)
 264                 b       8b
 265         UNWIND( .fnend                          )
 266
 267                 .endm
 268
 269
 270                 forward_copy_shift      pull=8  push=24
 271
 272 17:             forward_copy_shift      pull=16 push=16
 273
 274 18:             forward_copy_shift      pull=24 push=8
 275
 276
 277 /*
 278  * Abort preamble and completion macros.
 279  * If a fixup handler is required then those macros must surround it.
 280  * It is assumed that the fixup code will handle the private part of
 281  * the exit macro.
 282  */
 283
 284         .macro  copy_abort_preamble
 285 19:     ldmfd   sp!, {r5 - r9}
 286         b       21f
 287 20:     ldmfd   sp!, {r5 - r8}
 288 21:
 289         .endm
 290
 291         .macro  copy_abort_end
 292         ldmfd   sp!, {r4, pc}
 293         .endm
 294