51 lines
1.1 KiB
ArmAsm
51 lines
1.1 KiB
ArmAsm
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/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Based on arch/arm/lib/clear_user.S
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*
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* Copyright (C) 2012 ARM Ltd.
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*/
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#include <linux/linkage.h>
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#include <asm/asm-uaccess.h>
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#include <asm/assembler.h>
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.text
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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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* Alignment fixed up by hardware.
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*/
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ENTRY(__arch_clear_user)
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mov x2, x1 // save the size for fixup return
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subs x1, x1, #8
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b.mi 2f
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1:
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uao_user_alternative 9f, str, sttr, xzr, x0, 8
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subs x1, x1, #8
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b.pl 1b
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2: adds x1, x1, #4
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b.mi 3f
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uao_user_alternative 9f, str, sttr, wzr, x0, 4
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sub x1, x1, #4
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3: adds x1, x1, #2
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b.mi 4f
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uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
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sub x1, x1, #2
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4: adds x1, x1, #1
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b.mi 5f
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uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
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5: mov x0, #0
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ret
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ENDPROC(__arch_clear_user)
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EXPORT_SYMBOL(__arch_clear_user)
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.section .fixup,"ax"
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.align 2
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9: mov x0, x2 // return the original size
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ret
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.previous
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