gecko-dev/ef/Debugger/LinuxBreakPoint.cpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* The contents of this file are subject to the Netscape Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/NPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
*/
#include <stdio.h>
#include <signal.h>
#include <asm/sigcontext.h>
int old_instruction;
int
SetBreakPoint(void *pc)
{
old_instruction = *((unsigned char *) pc);
*((unsigned char *) pc) = 0xcc; /* break point opcode */
#ifdef DEBUG
fprintf(stderr, "breakpoint at: %x\n", (unsigned int) pc);
#endif
/* Need to flush icache here */
return old_instruction;
}
extern "C" void
sigtrap_handler(int sig, struct sigcontext_struct context)
{
#ifdef DEBUG
fprintf(stderr, "Handler: Restoring old instruction\n");
fprintf(stderr, "ip: %x\n", (unsigned int) context.eip);
#endif
/* Learnt this the hard way. eip points to the next instruction */
(*((unsigned char *) (context.eip -1))) = old_instruction;
context.eip = context.eip - 1;
/* Send a debugger event and do all kinds of things */
return;
}
void
SetupBreakPointHandler()
{
struct sigaction sigtrap_action;
sigemptyset(&sigtrap_action.sa_mask);
sigtrap_action.sa_flags = 0;
sigtrap_action.sa_handler = (__sighandler_t) sigtrap_handler;
sigaction(SIGTRAP, &sigtrap_action, NULL);
}