1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (C) 2005-2017 Andes Technology Corporation 3 4 #include <linux/linkage.h> 5 #include <asm/assembler.h> 6 #include <asm/errno.h> 7 8 /* Prototype: int __arch_clear_user(void *addr, size_t sz) 9 * Purpose : clear some user memory 10 * Params : addr - user memory address to clear 11 * : sz - number of bytes to clear 12 * Returns : number of bytes NOT cleared 13 */ 14 .text 15 .align 5 16 ENTRY(__arch_clear_user) 17 add $r5, $r0, $r1 18 beqz $r1, clear_exit 19 xor $p1, $p1, $p1 ! Use $p1=0 to clear mem 20 srli $p0, $r1, #2 ! $p0 = number of word to clear 21 andi $r1, $r1, #3 ! Bytes less than a word to copy 22 beqz $p0, byte_clear ! Only less than a word to clear 23 word_clear: 24 USER( smw.bim,$p1, [$r0], $p1) ! Clear the word 25 addi $p0, $p0, #-1 ! Decrease word count 26 bnez $p0, word_clear ! Continue looping to clear all words 27 beqz $r1, clear_exit ! No left bytes to copy 28 byte_clear: 29 USER( sbi.bi, $p1, [$r0], #1) ! Clear the byte 30 addi $r1, $r1, #-1 ! Decrease byte count 31 bnez $r1, byte_clear ! Continue looping to clear all left bytes 32 clear_exit: 33 move $r0, $r1 ! Set return value 34 ret 35 36 .section .fixup,"ax" 37 .align 0 38 9001: 39 sub $r0, $r5, $r0 ! Bytes left to copy 40 ret 41 .previous 42 ENDPROC(__arch_clear_user) 43