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71 lines
2.5 KiB
C
71 lines
2.5 KiB
C
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is ``mcount''
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corp. Portions created by the Initial Developer are
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* Copyright (C) 2001 the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Chris Waterson <waterson@netscape.com>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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/*
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A library that can be LD_PRELOAD-ed to dump a function's address on
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function entry.
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*/
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#include <unistd.h>
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/**
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* When compiled with `-pg' (or even just `-p'), gcc inserts a call to
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* |mcount| in each function prologue. This implementation of |mcount|
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* will grab the return address from the stack, and write it to stdout
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* as a binary stream, creating a gross execution trace the
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* instrumented program.
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*
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* For more info on gcc inline assembly, see:
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*
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* <http://www.ibm.com/developerworks/linux/library/l-ia.html?dwzone=linux>
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*
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*/
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void
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mcount()
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{
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register unsigned int caller;
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unsigned int buf[1];
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// Grab the return address.
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asm("movl 4(%%esp),%0"
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: "=r"(caller));
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buf[0] = caller;
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write(STDOUT_FILENO, buf, sizeof buf[0]);
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}
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