root/arch/unicore32/lib/clear_user.S

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * linux/arch/unicore32/lib/clear_user.S
   4  *
   5  * Code specific to PKUnity SoC and UniCore ISA
   6  *
   7  * Copyright (C) 2001-2010 GUAN Xue-tao
   8  */
   9 #include <linux/linkage.h>
  10 #include <asm/assembler.h>
  11 
  12                 .text
  13 
  14 /* Prototype: int __clear_user(void *addr, size_t sz)
  15  * Purpose  : clear some user memory
  16  * Params   : addr - user memory address to clear
  17  *          : sz   - number of bytes to clear
  18  * Returns  : number of bytes NOT cleared
  19  */
  20 WEAK(__clear_user)
  21                 stm.w   (lr), [sp-]
  22                 stm.w   (r1), [sp-]
  23                 mov     r2, #0
  24                 csub.a  r1, #4
  25                 bsl     2f
  26                 and.a   ip, r0, #3
  27                 beq     1f
  28                 csub.a  ip, #2
  29                 strusr  r2, r0, 1
  30                 strusr  r2, r0, 1, el
  31                 strusr  r2, r0, 1, sl
  32                 rsub    ip, ip, #4
  33                 sub     r1, r1, ip              @  7  6  5  4  3  2  1
  34 1:              sub.a   r1, r1, #8              @ -1 -2 -3 -4 -5 -6 -7
  35                 strusr  r2, r0, 4, ns, rept=2
  36                 bns     1b
  37                 add.a   r1, r1, #4              @  3  2  1  0 -1 -2 -3
  38                 strusr  r2, r0, 4, ns
  39 2:              cand.a  r1, #2                  @ 1x 1x 0x 0x 1x 1x 0x
  40                 strusr  r2, r0, 1, ne, rept=2
  41                 cand.a  r1, #1                  @ x1 x0 x1 x0 x1 x0 x1
  42                 beq     3f
  43 USER(           stb.u   r2, [r0])
  44 3:              mov     r0, #0
  45                 ldm.w   (r1), [sp]+
  46                 ldm.w   (pc), [sp]+
  47 ENDPROC(__clear_user)
  48 
  49                 .pushsection .fixup,"ax"
  50                 .align  0
  51 9001:           ldm.w   (r0), [sp]+
  52                 ldm.w   (pc), [sp]+
  53                 .popsection
  54