mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-12-26 18:31:29 +00:00
39 lines
995 B
C
39 lines
995 B
C
/* 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 http://mozilla.org/MPL/2.0/. */
|
|
|
|
/*
|
|
|
|
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:
|
|
*
|
|
* <http://www.ibm.com/developerworks/linux/library/l-ia.html?dwzone=linux>
|
|
*
|
|
*/
|
|
void
|
|
mcount()
|
|
{
|
|
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]);
|
|
}
|