| 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */
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| 2 | /*
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| 3 | *
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| 4 | * Copyright (C) IBM Corporation, 2012
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| 5 | *
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| 6 | * Author: Anton Blanchard <anton@au.ibm.com>
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| 7 | */
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| 8 |
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| 9 | |
| 10 | |
| 11 | |
| 12 | |
| 13 |
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| 14 | /**
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| 15 | * __arch_clear_user: - Zero a block of memory in user space, with less checking.
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| 16 | * @to: Destination address, in user space.
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| 17 | * @n: Number of bytes to zero.
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| 18 | *
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| 19 | * Zero a block of memory in user space. Caller must check
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| 20 | * the specified block with access_ok() before calling this function.
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| 21 | *
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| 22 | * Returns number of bytes that could not be cleared.
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| 23 | * On success, this will be zero.
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| 24 | */
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| 25 |
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| 26 | .macro err1
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| 27 | 100:
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| 28 | EX_TABLE(100b,.Ldo_err1)
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| 29 | .endm
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| 30 |
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| 31 | .macro err2
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| 32 | 200:
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| 33 | EX_TABLE(200b,.Ldo_err2)
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| 34 | .endm
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| 35 |
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| 36 | .macro err3
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| 37 | 300:
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| 38 | EX_TABLE(300b,.Ldo_err3)
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| 39 | .endm
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| 40 |
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| 41 | .Ldo_err1:
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| 42 | mr r3,r8
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| 43 |
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| 44 | .Ldo_err2:
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| 45 | mtctr r4
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| 46 | 1:
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| 47 | err3; stb r0,0(r3)
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| 48 | addi r3,r3,1
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| 49 | addi r4,r4,-1
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| 50 | bdnz 1b
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| 51 |
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| 52 | .Ldo_err3:
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| 53 | mr r3,r4
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| 54 | blr
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| 55 |
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| 56 | _GLOBAL_TOC(__arch_clear_user)
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| 57 | cmpdi r4,32
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| 58 | neg r6,r3
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| 59 | li r0,0
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| 60 | blt .Lshort_clear
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| 61 | mr r8,r3
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| 62 | mtocrf 0x01,r6
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| 63 | clrldi r6,r6,(64-3)
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| 64 |
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| 65 | /* Get the destination 8 byte aligned */
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| 66 | bf cr7*4+3,1f
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| 67 | err1; stb r0,0(r3)
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| 68 | addi r3,r3,1
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| 69 |
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| 70 | 1: bf cr7*4+2,2f
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| 71 | err1; sth r0,0(r3)
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| 72 | addi r3,r3,2
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| 73 |
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| 74 | 2: bf cr7*4+1,3f
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| 75 | err1; stw r0,0(r3)
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| 76 | addi r3,r3,4
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| 77 |
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| 78 | 3: sub r4,r4,r6
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| 79 |
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| 80 | cmpdi r4,32
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| 81 | cmpdi cr1,r4,512
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| 82 | blt .Lshort_clear
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| 83 | bgt cr1,.Llong_clear
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| 84 |
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| 85 | .Lmedium_clear:
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| 86 | srdi r6,r4,5
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| 87 | mtctr r6
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| 88 |
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| 89 | /* Do 32 byte chunks */
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| 90 | 4:
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| 91 | err2; std r0,0(r3)
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| 92 | err2; std r0,8(r3)
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| 93 | err2; std r0,16(r3)
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| 94 | err2; std r0,24(r3)
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| 95 | addi r3,r3,32
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| 96 | addi r4,r4,-32
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| 97 | bdnz 4b
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| 98 |
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| 99 | .Lshort_clear:
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| 100 | /* up to 31 bytes to go */
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| 101 | cmpdi r4,16
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| 102 | blt 6f
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| 103 | err2; std r0,0(r3)
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| 104 | err2; std r0,8(r3)
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| 105 | addi r3,r3,16
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| 106 | addi r4,r4,-16
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| 107 |
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| 108 | /* Up to 15 bytes to go */
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| 109 | 6: mr r8,r3
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| 110 | clrldi r4,r4,(64-4)
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| 111 | mtocrf 0x01,r4
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| 112 | bf cr7*4+0,7f
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| 113 | err1; std r0,0(r3)
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| 114 | addi r3,r3,8
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| 115 |
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| 116 | 7: bf cr7*4+1,8f
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| 117 | err1; stw r0,0(r3)
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| 118 | addi r3,r3,4
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| 119 |
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| 120 | 8: bf cr7*4+2,9f
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| 121 | err1; sth r0,0(r3)
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| 122 | addi r3,r3,2
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| 123 |
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| 124 | 9: bf cr7*4+3,10f
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| 125 | err1; stb r0,0(r3)
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| 126 |
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| 127 | 10: li r3,0
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| 128 | blr
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| 129 |
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| 130 | .Llong_clear:
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| 131 | LOAD_REG_ADDR(r5, ppc64_caches)
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| 132 |
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| 133 | bf cr7*4+0,11f
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| 134 | err2; std r0,0(r3)
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| 135 | addi r3,r3,8
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| 136 | addi r4,r4,-8
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| 137 |
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| 138 | /* Destination is 16 byte aligned, need to get it cache block aligned */
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| 139 | 11: lwz r7,DCACHEL1LOGBLOCKSIZE(r5)
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| 140 | lwz r9,DCACHEL1BLOCKSIZE(r5)
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| 141 |
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| 142 | /*
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| 143 | * With worst case alignment the long clear loop takes a minimum
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| 144 | * of 1 byte less than 2 cachelines.
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| 145 | */
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| 146 | sldi r10,r9,2
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| 147 | cmpd r4,r10
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| 148 | blt .Lmedium_clear
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| 149 |
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| 150 | neg r6,r3
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| 151 | addi r10,r9,-1
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| 152 | and. r5,r6,r10
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| 153 | beq 13f
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| 154 |
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| 155 | srdi r6,r5,4
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| 156 | mtctr r6
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| 157 | mr r8,r3
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| 158 | 12:
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| 159 | err1; std r0,0(r3)
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| 160 | err1; std r0,8(r3)
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| 161 | addi r3,r3,16
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| 162 | bdnz 12b
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| 163 |
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| 164 | sub r4,r4,r5
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| 165 |
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| 166 | 13: srd r6,r4,r7
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| 167 | mtctr r6
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| 168 | mr r8,r3
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| 169 | 14:
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| 170 | err1; dcbz 0,r3
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| 171 | add r3,r3,r9
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| 172 | bdnz 14b
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| 173 |
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| 174 | and r4,r4,r10
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| 175 |
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| 176 | cmpdi r4,32
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| 177 | blt .Lshort_clear
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| 178 | b .Lmedium_clear
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| 179 | EXPORT_SYMBOL(__arch_clear_user)
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