1*4882a593Smuzhiyun/* SPDX-License-Identifier: GPL-2.0-only */ 2*4882a593Smuzhiyun/* 3*4882a593Smuzhiyun * linux/arch/arm/lib/clear_user.S 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * Copyright (C) 1995, 1996,1997,1998 Russell King 6*4882a593Smuzhiyun */ 7*4882a593Smuzhiyun#include <linux/linkage.h> 8*4882a593Smuzhiyun#include <asm/assembler.h> 9*4882a593Smuzhiyun#include <asm/unwind.h> 10*4882a593Smuzhiyun 11*4882a593Smuzhiyun .text 12*4882a593Smuzhiyun 13*4882a593Smuzhiyun/* Prototype: unsigned long arm_clear_user(void *addr, size_t sz) 14*4882a593Smuzhiyun * Purpose : clear some user memory 15*4882a593Smuzhiyun * Params : addr - user memory address to clear 16*4882a593Smuzhiyun * : sz - number of bytes to clear 17*4882a593Smuzhiyun * Returns : number of bytes NOT cleared 18*4882a593Smuzhiyun */ 19*4882a593SmuzhiyunENTRY(__clear_user_std) 20*4882a593SmuzhiyunWEAK(arm_clear_user) 21*4882a593SmuzhiyunUNWIND(.fnstart) 22*4882a593SmuzhiyunUNWIND(.save {r1, lr}) 23*4882a593Smuzhiyun stmfd sp!, {r1, lr} 24*4882a593Smuzhiyun mov r2, #0 25*4882a593Smuzhiyun cmp r1, #4 26*4882a593Smuzhiyun blt 2f 27*4882a593Smuzhiyun ands ip, r0, #3 28*4882a593Smuzhiyun beq 1f 29*4882a593Smuzhiyun cmp ip, #2 30*4882a593Smuzhiyun strusr r2, r0, 1 31*4882a593Smuzhiyun strusr r2, r0, 1, le 32*4882a593Smuzhiyun strusr r2, r0, 1, lt 33*4882a593Smuzhiyun rsb ip, ip, #4 34*4882a593Smuzhiyun sub r1, r1, ip @ 7 6 5 4 3 2 1 35*4882a593Smuzhiyun1: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7 36*4882a593Smuzhiyun strusr r2, r0, 4, pl, rept=2 37*4882a593Smuzhiyun bpl 1b 38*4882a593Smuzhiyun adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3 39*4882a593Smuzhiyun strusr r2, r0, 4, pl 40*4882a593Smuzhiyun2: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x 41*4882a593Smuzhiyun strusr r2, r0, 1, ne, rept=2 42*4882a593Smuzhiyun tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1 43*4882a593Smuzhiyun it ne @ explicit IT needed for the label 44*4882a593SmuzhiyunUSER( strbtne r2, [r0]) 45*4882a593Smuzhiyun mov r0, #0 46*4882a593Smuzhiyun ldmfd sp!, {r1, pc} 47*4882a593SmuzhiyunUNWIND(.fnend) 48*4882a593SmuzhiyunENDPROC(arm_clear_user) 49*4882a593SmuzhiyunENDPROC(__clear_user_std) 50*4882a593Smuzhiyun 51*4882a593Smuzhiyun .pushsection .text.fixup,"ax" 52*4882a593Smuzhiyun .align 0 53*4882a593Smuzhiyun9001: ldmfd sp!, {r0, pc} 54*4882a593Smuzhiyun .popsection 55*4882a593Smuzhiyun 56