1/*
2 * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_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. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28
29#define __NO_UNDERSCORES__
30#include <i386/asm.h>
31#include <assym.s>
32
33Entry(mcount)
34        pushl   %ebp            	// setup mcount's frame
35        movl    %esp,%ebp
36        pushl	%eax			// save %eax
37        pushf				// save interrupt state
38        cli				// disable interrupts
39
40	//
41	// Check that this cpu is ready.
42	// This delays the start of mcounting until a cpu is really prepared.
43	//
44        mov		%gs, %ax
45		test	%ax, %ax
46	jz	1f
47
48        movl	%gs:CPU_RUNNING,%eax
49        testl	%eax,%eax
50	jz	1f
51
52	//
53	// Test for recursion as indicated by a per-cpu flag.
54	// Skip if nested, otherwise set the flag and call the C mount().
55	//
56        movl	%gs:CPU_MCOUNT_OFF,%eax
57        testl	%eax,%eax		// test for recursion
58        jnz	1f
59
60        incl	%gs:CPU_MCOUNT_OFF	// set recursion flag
61
62        movl    (%ebp),%eax     	// frame pointer of mcount's caller
63        movl    4(%eax),%eax    	// mcount's caller's return address
64        pushl   4(%ebp)         	// push selfpc parameter for mcount()
65        pushl   %eax            	// push frompc parameter for mcount()
66        call	_mcount			// call the C mcount
67	addl	$8,%esp			// pop args
68
69        decl	%gs:CPU_MCOUNT_OFF	// turn off recursion flag
701:
71        popf				// restore interrupt state
72        popl	%eax
73        movl    %ebp,%esp       	// tear down mcount's frame
74        popl    %ebp
75        ret
76