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 14 .text 15 16/* Prototype: unsigned long arm_clear_user(void *addr, size_t sz) 17 * Purpose : clear some user memory 18 * Params : addr - user memory address to clear 19 * : sz - number of bytes to clear 20 * Returns : number of bytes NOT cleared 21 */ 22ENTRY(__clear_user_std) 23WEAK(arm_clear_user) 24UNWIND(.fnstart) 25UNWIND(.save {r1, lr}) 26 stmfd sp!, {r1, lr} 27 mov r2, #0 28 cmp r1, #4 29 blt 2f 30 ands ip, r0, #3 31 beq 1f 32 cmp ip, #2 33 strusr r2, r0, 1 34 strusr r2, r0, 1, le 35 strusr r2, r0, 1, lt 36 rsb ip, ip, #4 37 sub r1, r1, ip @ 7 6 5 4 3 2 1 381: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7 39 strusr r2, r0, 4, pl, rept=2 40 bpl 1b 41 adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3 42 strusr r2, r0, 4, pl 432: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x 44 strusr r2, r0, 1, ne, rept=2 45 tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1 46 it ne @ explicit IT needed for the label 47USER( strnebt r2, [r0]) 48 mov r0, #0 49 ldmfd sp!, {r1, pc} 50UNWIND(.fnend) 51ENDPROC(arm_clear_user) 52ENDPROC(__clear_user_std) 53 54 .pushsection .text.fixup,"ax" 55 .align 0 569001: ldmfd sp!, {r0, pc} 57 .popsection 58 59