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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
33 Entry(mcount)
34 pushq %rbp // setup mcount's frame
35 movq %rsp,%rbp
36 pushq %rax // 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 movq (%rbp),%rax // frame pointer of mcount's caller
63 pushq %rdi
64 pushq %rsi
65 pushq %rdx
66 pushq %rcx
67 pushq %r8
68 pushq %r9
69 movq 8(%rax),%rdi // mcount's caller's return address
70 movq 8(%rbp),%rsi // push selfpc parameter for mcount()
71
72 call _mcount // call the C mcount
73
74 popq %r9
75 popq %r8
76 popq %rcx
77 popq %rdx
78 popq %rsi
79 popq %rdi
80
81 decl %gs:CPU_MCOUNT_OFF // turn off recursion flag
82 1:
83 popf // restore interrupt state
84 popq %rax
85 movq %rbp,%rsp // tear down mcount's frame
86 popq %rbp
87 ret