/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *  linux/arch/arm/lib/clear_user.S
 *
 *  Copyright (C) 1995, 1996,1997,1998 Russell King
 */
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/unwind.h>

                .text

/* Prototype: unsigned long arm_clear_user(void *addr, size_t sz)
 * Purpose  : clear some user memory
 * Params   : addr - user memory address to clear
 *          : sz   - number of bytes to clear
 * Returns  : number of bytes NOT cleared
 */
ENTRY(__clear_user_std)
WEAK(arm_clear_user)
UNWIND(.fnstart)
UNWIND(.save {r1, lr})
                stmfd   sp!, {r1, lr}
                mov     r2, #0
                cmp     r1, #4
                blt     2f
                ands    ip, r0, #3
                beq     1f
                cmp     ip, #2
                strusr  r2, r0, 1
                strusr  r2, r0, 1, le
                strusr  r2, r0, 1, lt
                rsb     ip, ip, #4
                sub     r1, r1, ip              @  7  6  5  4  3  2  1
1:              subs    r1, r1, #8              @ -1 -2 -3 -4 -5 -6 -7
                strusr  r2, r0, 4, pl, rept=2
                bpl     1b
                adds    r1, r1, #4              @  3  2  1  0 -1 -2 -3
                strusr  r2, r0, 4, pl
2:              tst     r1, #2                  @ 1x 1x 0x 0x 1x 1x 0x
                strusr  r2, r0, 1, ne, rept=2
                tst     r1, #1                  @ x1 x0 x1 x0 x1 x0 x1
                it      ne                      @ explicit IT needed for the label
USER(           strbtne r2, [r0])
                mov     r0, #0
                ldmfd   sp!, {r1, pc}
UNWIND(.fnend)
ENDPROC(arm_clear_user)
ENDPROC(__clear_user_std)

                .pushsection .text.fixup,"ax"
                .align  0
9001:           ldmfd   sp!, {r0, pc}
                .popsection