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#include <asm/unwind.h> 13#include <asm/export.h> 14 15 .text 16 17/* Prototype: unsigned long arm_clear_user(void *addr, size_t sz) 18 * Purpose : clear some user memory 19 * Params : addr - user memory address to clear 20 * : sz - number of bytes to clear 21 * Returns : number of bytes NOT cleared 22 */ 23ENTRY(__clear_user_std) 24WEAK(arm_clear_user) 25UNWIND(.fnstart) 26UNWIND(.save {r1, lr}) 27 stmfd sp!, {r1, lr} 28 mov r2, #0 29 cmp r1, #4 30 blt 2f 31 ands ip, r0, #3 32 beq 1f 33 cmp ip, #2 34 strusr r2, r0, 1 35 strusr r2, r0, 1, le 36 strusr r2, r0, 1, lt 37 rsb ip, ip, #4 38 sub r1, r1, ip @ 7 6 5 4 3 2 1 391: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7 40 strusr r2, r0, 4, pl, rept=2 41 bpl 1b 42 adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3 43 strusr r2, r0, 4, pl 442: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x 45 strusr r2, r0, 1, ne, rept=2 46 tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1 47 it ne @ explicit IT needed for the label 48USER( strnebt r2, [r0]) 49 mov r0, #0 50 ldmfd sp!, {r1, pc} 51UNWIND(.fnend) 52ENDPROC(arm_clear_user) 53ENDPROC(__clear_user_std) 54#ifndef CONFIG_UACCESS_WITH_MEMCPY 55EXPORT_SYMBOL(arm_clear_user) 56#endif 57 58 .pushsection .text.fixup,"ax" 59 .align 0 609001: ldmfd sp!, {r0, pc} 61 .popsection 62 63