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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 | /* * arch/mips/lib/copy_user.S * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (c) 1996, 1997 by Ralf Baechle * * Less stupid user_copy implementation for 32 bit MIPS CPUs. * * $Id: copy_user.S,v 1.2 1997/08/11 04:26:12 ralf Exp $ */ #include <asm/asm.h> #include <asm/regdef.h> #include <asm/mipsregs.h> #define BLOCK_SIZE 16 #define EX(addr,handler) \ .section __ex_table,"a"; \ PTR addr, handler; \ .previous #define UEX(addr,handler) \ EX(addr,handler); \ EX(addr+4,handler) .set noreorder .set noat /* ---------------------------------------------------------------------- */ /* * Bad. We can't fix the alignment for both address parts. * Align the source address and copy slowly ... */ not_even_the_same_alignment: LONG_SUBU v1,zero,a1 andi v1,3 sltu t0,v0,v1 MOVN(v1,v0,t0) beqz v1,src_aligned LONG_ADDU v1,a0 1: lb $1,(a1) EX(1b, fault) LONG_ADDIU a1,1 2: sb $1,(a0) EX(2b, fault) LONG_ADDIU a0,1 bne a0,v1,1b LONG_SUBU v0,1 src_aligned: /* * Ok. We've fixed the alignment of the copy src for this case. * Now let's copy in the usual BLOCK_SIZE byte blocks using unaligned * stores. * XXX Align the destination address. This is better if the __copy_user * encounters an access fault because we never have to deal with an * only partially modified destination word. This is required to * keep the semantics of the result of copy_*_user(). */ ori v1,v0,BLOCK_SIZE-1 xori v1,BLOCK_SIZE-1 beqz v1,copy_left_over nop LONG_SUBU v0,v1 LONG_ADDU v1,a0 1: lw t0,(a1) # Can cause tlb fault EX(1b, fault) 2: lw t1,4(a1) # Can cause tlb fault EX(2b, fault) 2: lw t2,8(a1) # Can cause tlb fault EX(2b, fault) 2: lw t3,12(a1) # Can cause tlb fault EX(2b, fault) 2: usw t0,(a0) # Can cause tlb faults UEX(2b, fault) 2: usw t1,4(a0) # Can cause tlb faults UEX(2b, fault_plus_4) 2: usw t2,8(a0) # Can cause tlb faults UEX(2b, fault_plus_8) 2: usw t3,12(a0) # Can cause tlb faults UEX(2b, fault_plus_12) LONG_ADDIU a0,BLOCK_SIZE bne a0,v1,1b LONG_ADDIU a1,BLOCK_SIZE 9: b copy_left_over # < BLOCK_SIZE bytes left nop /* ---------------------------------------------------------------------- */ not_w_aligned: /* * Ok, src or destination are not 4-byte aligned. * Try to fix that. Do at least both addresses have the same alignment? */ xor t0,a0,a1 andi t0,3 bnez t0,not_even_the_same_alignment nop # delay slot /* * Ok, we can fix the alignment for both operands and go back to the * fast path. We have to copy at least one byte, on average 3 bytes * bytewise. */ LONG_SUBU v1,zero,a0 andi v1,3 sltu t0,v0,v1 MOVN(v1,v0,t0) beqz v1,__copy_user LONG_ADDU v1,a0 1: lb $1,(a1) EX(1b, fault) LONG_ADDIU a1,1 2: sb $1,(a0) EX(2b, fault) LONG_ADDIU a0,1 bne a0,v1,1b LONG_SUBU v0,1 b align4 nop /* ---------------------------------------------------------------------- */ LEAF(__copy_user) or t1,a0,a1 andi t1,3 bnez t1,not_w_aligned # not word alignment move v0,a2 align4: ori v1,v0,BLOCK_SIZE-1 xori v1,BLOCK_SIZE-1 beqz v1,copy_left_over nop LONG_SUBU v0,v1 LONG_ADDU v1,a0 1: lw t0,(a1) # Can cause tlb fault EX(1b, fault) 2: lw t1,4(a1) # Can cause tlb fault EX(2b, fault) 2: lw t2,8(a1) # Can cause tlb fault EX(2b, fault) 2: lw t3,12(a1) # Can cause tlb fault EX(2b, fault) 2: sw t0,(a0) # Can cause tlb fault EX(2b, fault) 2: sw t1,4(a0) # Can cause tlb fault EX(2b, fault_plus_4) 2: sw t2,8(a0) # Can cause tlb fault EX(2b, fault_plus_8) 2: sw t3,12(a0) # Can cause tlb fault EX(2b, fault_plus_12) LONG_ADDIU a0,BLOCK_SIZE bne a0,v1,1b LONG_ADDIU a1,BLOCK_SIZE 9: /* * XXX Tune me ... */ copy_left_over: beqz v0,3f nop 1: lb $1,(a1) EX(1b, fault) LONG_ADDIU a1,1 2: sb $1,(a0) EX(2b, fault) LONG_SUBU v0,1 bnez v0,1b LONG_ADDIU a0,1 3: done: jr ra nop END(__copy_user) .set at .set reorder /* ---------------------------------------------------------------------- */ /* * Access fault. The number of not copied bytes is in v0. We have to * correct the number of the not copied bytes in v0 in case of a access * fault in an unrolled loop, then return. */ fault: jr ra fault_plus_4: LONG_ADDIU v0,4 jr ra fault_plus_8: LONG_ADDIU v0,8 jr ra fault_plus_12: LONG_ADDIU v0,12 jr ra |