1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * Based on arch/arm/lib/clear_user.S 4 * 5 * Copyright (C) 2012 ARM Ltd. 6 */ 7#include <linux/linkage.h> 8 9#include <asm/asm-uaccess.h> 10#include <asm/assembler.h> 11 12 .text 13 14/* Prototype: int __arch_clear_user(void *addr, size_t sz) 15 * Purpose : clear some user memory 16 * Params : addr - user memory address to clear 17 * : sz - number of bytes to clear 18 * Returns : number of bytes NOT cleared 19 * 20 * Alignment fixed up by hardware. 21 */ 22ENTRY(__arch_clear_user) 23 mov x2, x1 // save the size for fixup return 24 subs x1, x1, #8 25 b.mi 2f 261: 27uao_user_alternative 9f, str, sttr, xzr, x0, 8 28 subs x1, x1, #8 29 b.pl 1b 302: adds x1, x1, #4 31 b.mi 3f 32uao_user_alternative 9f, str, sttr, wzr, x0, 4 33 sub x1, x1, #4 343: adds x1, x1, #2 35 b.mi 4f 36uao_user_alternative 9f, strh, sttrh, wzr, x0, 2 37 sub x1, x1, #2 384: adds x1, x1, #1 39 b.mi 5f 40uao_user_alternative 9f, strb, sttrb, wzr, x0, 0 415: mov x0, #0 42 ret 43ENDPROC(__arch_clear_user) 44EXPORT_SYMBOL(__arch_clear_user) 45 46 .section .fixup,"ax" 47 .align 2 489: mov x0, x2 // return the original size 49 ret 50 .previous 51