mirror of https://gitee.com/openkylin/linux.git
43 lines
1.2 KiB
ArmAsm
43 lines
1.2 KiB
ArmAsm
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// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2005-2017 Andes Technology Corporation
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/errno.h>
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/* Prototype: int __arch_clear_user(void *addr, size_t sz)
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* Purpose : clear some user memory
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* Params : addr - user memory address to clear
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* : sz - number of bytes to clear
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* Returns : number of bytes NOT cleared
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*/
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.text
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.align 5
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ENTRY(__arch_clear_user)
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add $r5, $r0, $r1
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beqz $r1, clear_exit
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xor $p1, $p1, $p1 ! Use $p1=0 to clear mem
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srli $p0, $r1, #2 ! $p0 = number of word to clear
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andi $r1, $r1, #3 ! Bytes less than a word to copy
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beqz $p0, byte_clear ! Only less than a word to clear
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word_clear:
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USER( smw.bim,$p1, [$r0], $p1) ! Clear the word
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addi $p0, $p0, #-1 ! Decrease word count
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bnez $p0, word_clear ! Continue looping to clear all words
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beqz $r1, clear_exit ! No left bytes to copy
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byte_clear:
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USER( sbi.bi, $p1, [$r0], #1) ! Clear the byte
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addi $r1, $r1, #-1 ! Decrease byte count
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bnez $r1, byte_clear ! Continue looping to clear all left bytes
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clear_exit:
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move $r0, $r1 ! Set return value
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ret
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.section .fixup,"ax"
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.align 0
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9001:
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sub $r0, $r5, $r0 ! Bytes left to copy
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ret
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.previous
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ENDPROC(__arch_clear_user)
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