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50 lines
1.0 KiB
50 lines
1.0 KiB
/* 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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SYM_FUNC_START(__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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user_ldst 9f, 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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user_ldst 9f, 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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user_ldst 9f, 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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user_ldst 9f, sttrb, wzr, x0, 0 |
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5: mov x0, #0 |
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ret |
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SYM_FUNC_END(__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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