arch/x86/lib/cmpxchg8b_emu.S

   1 /*
   2  *      This program is free software; you can redistribute it and/or
   3  *      modify it under the terms of the GNU General Public License
   4  *      as published by the Free Software Foundation; version 2
   5  *      of the License.
   6  *
   7  */
   8
   9 #include <linux/linkage.h>
  10
  11 .text
  12
  13 /*
  14  * Inputs:
  15  * %esi : memory location to compare
  16  * %eax : low 32 bits of old value
  17  * %edx : high 32 bits of old value
  18  * %ebx : low 32 bits of new value
  19  * %ecx : high 32 bits of new value
  20  */
  21 ENTRY(cmpxchg8b_emu)
  22
  23 #
  24 # Emulate 'cmpxchg8b (%esi)' on UP except we don't
  25 # set the whole ZF thing (caller will just compare
  26 # eax:edx with the expected value)
  27 #
  28         pushfl
  29         cli
  30
  31         cmpl  (%esi), %eax
  32         jne .Lnot_same
  33         cmpl 4(%esi), %edx
  34         jne .Lhalf_same
  35
  36         movl %ebx,  (%esi)
  37         movl %ecx, 4(%esi)
  38
  39         popfl
  40         ret
  41
  42 .Lnot_same:
  43         movl  (%esi), %eax
  44 .Lhalf_same:
  45         movl 4(%esi), %edx
  46
  47         popfl
  48         ret
  49
  50 ENDPROC(cmpxchg8b_emu)