diff options
Diffstat (limited to 'arch/nds32/lib/clear_user.S')
| -rw-r--r-- | arch/nds32/lib/clear_user.S | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/nds32/lib/clear_user.S b/arch/nds32/lib/clear_user.S new file mode 100644 index 000000000000..805dfcd25bf8 --- /dev/null +++ b/arch/nds32/lib/clear_user.S @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2005-2017 Andes Technology Corporation + +#include <linux/linkage.h> +#include <asm/assembler.h> +#include <asm/errno.h> + +/* Prototype: int __arch_clear_user(void *addr, size_t sz) + * Purpose : clear some user memory + * Params : addr - user memory address to clear + * : sz - number of bytes to clear + * Returns : number of bytes NOT cleared + */ + .text + .align 5 +ENTRY(__arch_clear_user) + add $r5, $r0, $r1 + beqz $r1, clear_exit + xor $p1, $p1, $p1 ! Use $p1=0 to clear mem + srli $p0, $r1, #2 ! $p0 = number of word to clear + andi $r1, $r1, #3 ! Bytes less than a word to copy + beqz $p0, byte_clear ! Only less than a word to clear +word_clear: +USER( smw.bim,$p1, [$r0], $p1) ! Clear the word + addi $p0, $p0, #-1 ! Decrease word count + bnez $p0, word_clear ! Continue looping to clear all words + beqz $r1, clear_exit ! No left bytes to copy +byte_clear: +USER( sbi.bi, $p1, [$r0], #1) ! Clear the byte + addi $r1, $r1, #-1 ! Decrease byte count + bnez $r1, byte_clear ! Continue looping to clear all left bytes +clear_exit: + move $r0, $r1 ! Set return value + ret + + .section .fixup,"ax" + .align 0 +9001: + sub $r0, $r5, $r0 ! Bytes left to copy + ret + .previous +ENDPROC(__arch_clear_user) |