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