1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * linux/arch/arm/lib/clear_user.S 4 * 5 * Copyright (C) 1995, 1996,1997,1998 Russell King 6 */ 7 #include <linux/linkage.h> 8 #include <asm/assembler.h> 9 #include <asm/unwind.h> 10 11 .text 12 13 /* Prototype: unsigned long arm_clear_user(void *addr, size_t sz) 14 * Purpose : clear some user memory 15 * Params : addr - user memory address to clear 16 * : sz - number of bytes to clear 17 * Returns : number of bytes NOT cleared 18 */ 19 ENTRY(__clear_user_std) 20 WEAK(arm_clear_user) 21 UNWIND(.fnstart) 22 UNWIND(.save {r1, lr}) 23 stmfd sp!, {r1, lr} 24 mov r2, #0 25 cmp r1, #4 26 blt 2f 27 ands ip, r0, #3 28 beq 1f 29 cmp ip, #2 30 strusr r2, r0, 1 31 strusr r2, r0, 1, le 32 strusr r2, r0, 1, lt 33 rsb ip, ip, #4 34 sub r1, r1, ip @ 7 6 5 4 3 2 1 35 1: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7 36 strusr r2, r0, 4, pl, rept=2 37 bpl 1b 38 adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3 39 strusr r2, r0, 4, pl 40 2: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x 41 strusr r2, r0, 1, ne, rept=2 42 tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1 43 it ne @ explicit IT needed for the label 44 USER( strbtne r2, [r0]) 45 mov r0, #0 46 ldmfd sp!, {r1, pc} 47 UNWIND(.fnend) 48 ENDPROC(arm_clear_user) 49 ENDPROC(__clear_user_std) 50 51 .pushsection .text.fixup,"ax" 52 .align 0 53 9001: ldmfd sp!, {r0, pc} 54 .popsection 55 56