/*
* Copyright (c) 2010 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed by Rui Paulo under sponsorship from the
* FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifdef __FBSDID
__FBSDID("$FreeBSD: head/lib/libproc/proc_bkpt.c 287106 2015-08-24 12:17:15Z andrew $");
#else
__RCSID("$NetBSD: proc_bkpt.c,v 1.6 2018/07/20 20:50:34 christos Exp $");
#endif
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <assert.h>
#include <string.h>
#include <err.h>
#include <errno.h>
#include <inttypes.h>
#include <signal.h>
#include <stdio.h>
#include "_libproc.h"
#ifndef PTRACE_BREAKPOINT
#error "Add support for your architecture"
#endif
static int
proc_stop(struct proc_handle *phdl)
{
int status;
if (kill(proc_getpid(phdl), SIGSTOP) == -1) {
DPRINTF("kill %d", proc_getpid(phdl));
return (-1);
} else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) {
DPRINTF("waitpid %d", proc_getpid(phdl));
return (-1);
} else if (!WIFSTOPPED(status)) {
DPRINTFX("waitpid: unexpected status 0x%x", status);
return (-1);
}
return (0);
}
int
proc_bkptset(struct proc_handle *phdl, uintptr_t address,
proc_breakpoint_t *saved)
{
struct ptrace_io_desc piod;
unsigned long paddr, caddr;
int ret = 0, stopped;
proc_breakpoint_t copy;
if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
phdl->status == PS_IDLE) {
errno = ENOENT;
return (-1);
}
DPRINTFX("adding breakpoint at 0x%" PRIxPTR, address);
stopped = 0;
if (phdl->status != PS_STOP) {
if (proc_stop(phdl) != 0)
return (-1);
stopped = 1;
}
/*
* Read the original instruction.
*/
caddr = address;
paddr = 0;
piod.piod_op = PIOD_READ_I;
piod.piod_offs = (void *)caddr;
piod.piod_addr = (void *)saved->data;
piod.piod_len = sizeof(saved->data);
if (ptrace(PT_IO, proc_getpid(phdl), &piod, 0) < 0) {
DPRINTF("ERROR: couldn't read instruction at address 0x%"
PRIxPTR, address);
ret = -1;
goto done;
}
/*
* Write a breakpoint instruction to that address.
*/
caddr = address;
piod.piod_op = PIOD_WRITE_I;
piod.piod_offs = (void *)caddr;
piod.piod_addr = (void *)PTRACE_BREAKPOINT;
piod.piod_len = sizeof(PTRACE_BREAKPOINT);
if (ptrace(PT_IO, proc_getpid(phdl), &piod, 0) < 0) {
DPRINTF("ERROR: couldn't write instruction at address 0x%"
PRIxPTR, address);
ret = -1;
goto done;
}
done:
if (stopped)
/* Restart the process if we had to stop it. */
proc_continue(phdl);
return (ret);
}
int
proc_bkptdel(struct proc_handle *phdl, uintptr_t address,
proc_breakpoint_t *saved)
{
struct ptrace_io_desc piod;
unsigned long paddr, caddr;
int ret = 0, stopped;
if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
phdl->status == PS_IDLE) {
errno = ENOENT;
return (-1);
}
DPRINTFX("removing breakpoint at 0x%" PRIxPTR, address);
stopped = 0;
if (phdl->status != PS_STOP) {
if (proc_stop(phdl) != 0)
return (-1);
stopped = 1;
}
/*
* Overwrite the breakpoint instruction that we setup previously.
*/
caddr = address;
piod.piod_op = PIOD_WRITE_I;
piod.piod_offs = (void *)caddr;
piod.piod_addr = (void *)saved->data;
piod.piod_len = sizeof(saved->data);
if (ptrace(PT_IO, proc_getpid(phdl), &piod, 0) < 0) {
DPRINTF("ERROR: couldn't write instruction at address 0x%"
PRIxPTR, address);
ret = -1;
}
if (stopped)
/* Restart the process if we had to stop it. */
proc_continue(phdl);
return (ret);
}
/*
* Decrement pc so that we delete the breakpoint at the correct
* address, i.e. at the breakpoint instruction address.
*
* This is only needed on some architectures where the pc value
* when reading registers points at the instruction after the
* breakpoint, e.g. x86.
*/
void
proc_bkptregadj(unsigned long *pc)
{
(void)pc;
#ifdef PTRACE_BREAKPOINT_ADJ
*pc = *pc - PTRACE_BREAKPOINT_ADJ;
#endif
}
/*
* Step over the breakpoint.
*/
int
proc_bkptexec(struct proc_handle *phdl, proc_breakpoint_t *saved)
{
unsigned long pc;
proc_breakpoint_t samesaved;
int status;
if (proc_regget(phdl, REG_PC, &pc) < 0) {
DPRINTFX("ERROR: couldn't get PC register");
return (-1);
}
proc_bkptregadj(&pc);
if (proc_bkptdel(phdl, pc, saved) < 0) {
DPRINTFX("ERROR: couldn't delete breakpoint");
return (-1);
}
/*
* Go back in time and step over the new instruction just
* set up by proc_bkptdel().
*/
proc_regset(phdl, REG_PC, pc);
#ifdef PT_STEP
if (ptrace(PT_STEP, proc_getpid(phdl), (void *)(intptr_t)1, 0) < 0) {
DPRINTFX("ERROR: ptrace step failed");
return (-1);
}
#endif
proc_wstatus(phdl);
status = proc_getwstat(phdl);
if (!WIFSTOPPED(status)) {
DPRINTFX("ERROR: don't know why process stopped");
return (-1);
}
/*
* Restore the breakpoint. The saved instruction should be
* the same as the one that we were passed in.
*/
if (proc_bkptset(phdl, pc, &samesaved) < 0) {
DPRINTFX("ERROR: couldn't restore breakpoint");
return (-1);
}
assert(memcmp(saved, &samesaved, sizeof(samesaved)) == 0);
return (0);
}
