clear_user.S
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/*
* linux/arch/unicore32/lib/clear_user.S
*
* Code specific to PKUnity SoC and UniCore ISA
*
* Copyright (C) 2001-2010 GUAN Xue-tao
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
.text
/* Prototype: int __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
*/
WEAK(__clear_user)
stm.w (lr), [sp-]
stm.w (r1), [sp-]
mov r2, #0
csub.a r1, #4
bsl 2f
and.a ip, r0, #3
beq 1f
csub.a ip, #2
strusr r2, r0, 1
strusr r2, r0, 1, el
strusr r2, r0, 1, sl
rsub ip, ip, #4
sub r1, r1, ip @ 7 6 5 4 3 2 1
1: sub.a r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7
strusr r2, r0, 4, ns, rept=2
bns 1b
add.a r1, r1, #4 @ 3 2 1 0 -1 -2 -3
strusr r2, r0, 4, ns
2: cand.a r1, #2 @ 1x 1x 0x 0x 1x 1x 0x
strusr r2, r0, 1, ne, rept=2
cand.a r1, #1 @ x1 x0 x1 x0 x1 x0 x1
beq 3f
USER( stb.u r2, [r0])
3: mov r0, #0
ldm.w (r1), [sp]+
ldm.w (pc), [sp]+
ENDPROC(__clear_user)
.pushsection .fixup,"ax"
.align 0
9001: ldm.w (r0), [sp]+
ldm.w (pc), [sp]+
.popsection