arch/x86/lib/semaphore_32.S

   1 /*
   2  * i386 semaphore implementation.
   3  *
   4  * (C) Copyright 1999 Linus Torvalds
   5  *
   6  * Portions Copyright 1999 Red Hat, Inc.
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of the GNU General Public License
  10  *      as published by the Free Software Foundation; either version
  11  *      2 of the License, or (at your option) any later version.
  12  *
  13  * rw semaphores implemented November 1999 by Benjamin LaHaise <bcrl@kvack.org>
  14  */
  15
  16 #include <linux/linkage.h>
  17 #include <asm/frame.h>
  18 #include <asm/dwarf2.h>
  19
  20 /*
  21  * The semaphore operations have a special calling sequence that
  22  * allow us to do a simpler in-line version of them. These routines
  23  * need to convert that sequence back into the C sequence when
  24  * there is contention on the semaphore.
  25  *
  26  * %eax contains the semaphore pointer on entry. Save the C-clobbered
  27  * registers (%eax, %edx and %ecx) except %eax whish is either a return
  28  * value or just clobbered..
  29  */
  30         .section .sched.text, "ax"
  31
  32 /* Fix up special calling conventions */
  33 ENTRY(call_rwsem_down_read_failed)
  34         CFI_STARTPROC
  35         pushl_cfi %ecx
  36         CFI_REL_OFFSET ecx,0
  37         pushl_cfi %edx
  38         CFI_REL_OFFSET edx,0
  39         call rwsem_down_read_failed
  40         popl_cfi %edx
  41         popl_cfi %ecx
  42         ret
  43         CFI_ENDPROC
  44         ENDPROC(call_rwsem_down_read_failed)
  45
  46 ENTRY(call_rwsem_down_write_failed)
  47         CFI_STARTPROC
  48         pushl_cfi %ecx
  49         CFI_REL_OFFSET ecx,0
  50         calll rwsem_down_write_failed
  51         popl_cfi %ecx
  52         ret
  53         CFI_ENDPROC
  54         ENDPROC(call_rwsem_down_write_failed)
  55
  56 ENTRY(call_rwsem_wake)
  57         CFI_STARTPROC
  58         decw %dx    /* do nothing if still outstanding active readers */
  59         jnz 1f
  60         pushl_cfi %ecx
  61         CFI_REL_OFFSET ecx,0
  62         call rwsem_wake
  63         popl_cfi %ecx
  64 1:      ret
  65         CFI_ENDPROC
  66         ENDPROC(call_rwsem_wake)
  67
  68 /* Fix up special calling conventions */
  69 ENTRY(call_rwsem_downgrade_wake)
  70         CFI_STARTPROC
  71         pushl_cfi %ecx
  72         CFI_REL_OFFSET ecx,0
  73         pushl_cfi %edx
  74         CFI_REL_OFFSET edx,0
  75         call rwsem_downgrade_wake
  76         popl_cfi %edx
  77         popl_cfi %ecx
  78         ret
  79         CFI_ENDPROC
  80         ENDPROC(call_rwsem_downgrade_wake)