1/* 2 * linux/arch/arm/lib/clear_user.S 3 * 4 * Copyright (C) 1995, 1996,1997,1998 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10#include <linux/linkage.h> 11#include <asm/assembler.h> 12 13 .text 14 15/* Prototype: int __clear_user(void *addr, size_t sz) 16 * Purpose : clear some user memory 17 * Params : addr - user memory address to clear 18 * : sz - number of bytes to clear 19 * Returns : number of bytes NOT cleared 20 */ 21ENTRY(__clear_user) 22 stmfd sp!, {r1, lr} 23 mov r2, #0 24 cmp r1, #4 25 blt 2f 26 ands ip, r0, #3 27 beq 1f 28 cmp ip, #2 29USER( strbt r2, [r0], #1) 30USER( strlebt r2, [r0], #1) 31USER( strltbt r2, [r0], #1) 32 rsb ip, ip, #4 33 sub r1, r1, ip @ 7 6 5 4 3 2 1 341: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7 35USER( strplt r2, [r0], #4) 36USER( strplt r2, [r0], #4) 37 bpl 1b 38 adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3 39USER( strplt r2, [r0], #4) 402: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x 41USER( strnebt r2, [r0], #1) 42USER( strnebt r2, [r0], #1) 43 tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1 44USER( strnebt r2, [r0], #1) 45 mov r0, #0 46 ldmfd sp!, {r1, pc} 47 48 .section .fixup,"ax" 49 .align 0 509001: ldmfd sp!, {r0, pc} 51 .previous 52 53