powerpc/lib/string_32.S

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002
0003 /*
0004  * String handling functions for PowerPC32
0005  *
0006  * Copyright (C) 1996 Paul Mackerras.
0007  *
0008  */
0009
0010 #include <asm/ppc_asm.h>
0011 #include <asm/export.h>
0012 #include <asm/cache.h>
0013
0014     .text
0015
0016 CACHELINE_BYTES = L1_CACHE_BYTES
0017 LG_CACHELINE_BYTES = L1_CACHE_SHIFT
0018 CACHELINE_MASK = (L1_CACHE_BYTES-1)
0019
0020 _GLOBAL(__arch_clear_user)
0021 /*
0022  * Use dcbz on the complete cache lines in the destination
0023  * to set them to zero.  This requires that the destination
0024  * area is cacheable.
0025  */
0026     cmplwi  cr0, r4, 4
0027     mr  r10, r3
0028     li  r3, 0
0029     blt 7f
0030
0031 11: stw r3, 0(r10)
0032     beqlr
0033     andi.   r0, r10, 3
0034     add r11, r0, r4
0035     subf    r6, r0, r10
0036
0037     clrlwi  r7, r6, 32 - LG_CACHELINE_BYTES
0038     add r8, r7, r11
0039     srwi    r9, r8, LG_CACHELINE_BYTES
0040     addic.  r9, r9, -1  /* total number of complete cachelines */
0041     ble 2f
0042     xori    r0, r7, CACHELINE_MASK & ~3
0043     srwi.   r0, r0, 2
0044     beq 3f
0045     mtctr   r0
0046 4:  stwu    r3, 4(r6)
0047     bdnz    4b
0048 3:  mtctr   r9
0049     li  r7, 4
0050 10: dcbz    r7, r6
0051     addi    r6, r6, CACHELINE_BYTES
0052     bdnz    10b
0053     clrlwi  r11, r8, 32 - LG_CACHELINE_BYTES
0054     addi    r11, r11, 4
0055
0056 2:  srwi    r0 ,r11 ,2
0057     mtctr   r0
0058     bdz 6f
0059 1:  stwu    r3, 4(r6)
0060     bdnz    1b
0061 6:  andi.   r11, r11, 3
0062     beqlr
0063     mtctr   r11
0064     addi    r6, r6, 3
0065 8:  stbu    r3, 1(r6)
0066     bdnz    8b
0067     blr
0068
0069 7:  cmpwi   cr0, r4, 0
0070     beqlr
0071     mtctr   r4
0072     addi    r6, r10, -1
0073 9:  stbu    r3, 1(r6)
0074     bdnz    9b
0075     blr
0076
0077 90: mr  r3, r4
0078     blr
0079 91: add r3, r10, r4
0080     subf    r3, r6, r3
0081     blr
0082
0083     EX_TABLE(11b, 90b)
0084     EX_TABLE(4b, 91b)
0085     EX_TABLE(10b, 91b)
0086     EX_TABLE(1b, 91b)
0087     EX_TABLE(8b, 91b)
0088     EX_TABLE(9b, 91b)
0089
0090 EXPORT_SYMBOL(__arch_clear_user)