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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
|
|
