author Kyle Machulis <>
Fri, 29 Mar 2013 15:12:58 -0700
changeset 137136 0db3022ca2e6bec95897850f797f078464a7f529
parent 98529 f4157e8c410708d76703f19e4dfb61859bfe32d8
permissions -rw-r--r--
Backout for changeset 03452b187c14 (Bug 855465) due to bustage on a CLOSED TREE; r=qdot

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at */


  A library that can be LD_PRELOAD-ed to dump a function's address on
  function entry.


#include <unistd.h>

 * When compiled with `-pg' (or even just `-p'), gcc inserts a call to
 * |mcount| in each function prologue. This implementation of |mcount|
 * will grab the return address from the stack, and write it to stdout
 * as a binary stream, creating a gross execution trace the
 * instrumented program.
 * For more info on gcc inline assembly, see:
 *   <>
    register unsigned int caller;
    unsigned int buf[1];

    // Grab the return address. 
    asm("movl 4(%%esp),%0"
        : "=r"(caller));

    buf[0] = caller;
    write(STDOUT_FILENO, buf, sizeof buf[0]);