osfmk/i386/mcount.s

   1 /*
   2  * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #define __NO_UNDERSCORES__
  25 #include <i386/asm.h>
  26 #include <assym.s>
  27
  28 Entry(mcount)
  29         pushl   %ebp                    // setup mcount's frame
  30         movl    %esp,%ebp
  31         pushl   %eax                    // save %eax
  32         pushf                           // save interrupt state
  33         cli                             // disable interrupts
  34
  35         //
  36         // Check that this cpu is ready.
  37         // This delays the start of mcounting until a cpu is really prepared.
  38         //
  39         movl    %gs:CPU_RUNNING,%eax
  40         testl   %eax,%eax
  41         jz      1f
  42
  43         //
  44         // Test for recursion as indicated by a per-cpu flag.
  45         // Skip if nested, otherwise set the flag and call the C mount().
  46         //
  47         movl    %gs:CPU_MCOUNT_OFF,%eax
  48         testl   %eax,%eax               // test for recursion
  49         jnz     1f
  50
  51         incl    %gs:CPU_MCOUNT_OFF      // set recursion flag
  52
  53         movl    (%ebp),%eax             // frame pointer of mcount's caller
  54         movl    4(%eax),%eax            // mcount's caller's return address
  55         pushl   4(%ebp)                 // push selfpc parameter for mcount()
  56         pushl   %eax                    // push frompc parameter for mcount()
  57         call    _mcount                 // call the C mcount
  58         addl    $8,%esp                 // pop args
  59
  60         decl    %gs:CPU_MCOUNT_OFF      // turn off recursion flag
  61 1:
  62         popf                            // restore interrupt state
  63         popl    %eax
  64         movl    %ebp,%esp               // tear down mcount's frame
  65         popl    %ebp
  66         ret