mirror of https://gitee.com/openkylin/linux.git
59 lines
1.4 KiB
ArmAsm
59 lines
1.4 KiB
ArmAsm
/*
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* linux/arch/arm/lib/clear_user.S
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*
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* Copyright (C) 1995, 1996,1997,1998 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/unwind.h>
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.text
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/* Prototype: unsigned long arm_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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ENTRY(__clear_user_std)
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WEAK(arm_clear_user)
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UNWIND(.fnstart)
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UNWIND(.save {r1, lr})
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stmfd sp!, {r1, lr}
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mov r2, #0
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cmp r1, #4
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blt 2f
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ands ip, r0, #3
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beq 1f
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cmp ip, #2
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strusr r2, r0, 1
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strusr r2, r0, 1, le
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strusr r2, r0, 1, lt
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rsb ip, ip, #4
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sub r1, r1, ip @ 7 6 5 4 3 2 1
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1: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7
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strusr r2, r0, 4, pl, rept=2
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bpl 1b
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adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3
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strusr r2, r0, 4, pl
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2: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x
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strusr r2, r0, 1, ne, rept=2
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tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1
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it ne @ explicit IT needed for the label
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USER( strbtne r2, [r0])
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mov r0, #0
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ldmfd sp!, {r1, pc}
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UNWIND(.fnend)
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ENDPROC(arm_clear_user)
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ENDPROC(__clear_user_std)
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.pushsection .text.fixup,"ax"
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.align 0
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9001: ldmfd sp!, {r0, pc}
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.popsection
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