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breakpoints.c
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breakpoints.c
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/*
* This file is part of ltrace.
* Copyright (C) 2006,2007,2011,2012,2013,2014 Petr Machata, Red Hat Inc.
* Copyright (C) 2009 Juan Cespedes
* Copyright (C) 1998,2001,2002,2003,2007,2008,2009 Juan Cespedes
* Copyright (C) 2006 Ian Wienand
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#include "config.h"
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef __powerpc__
#include <sys/ptrace.h>
#endif
#include "backend.h"
#include "breakpoint.h"
#include "debug.h"
#include "library.h"
#include "ltrace-elf.h"
#include "proc.h"
#ifndef ARCH_HAVE_TRANSLATE_ADDRESS
int
arch_translate_address_dyn(struct process *proc,
arch_addr_t addr, arch_addr_t *ret)
{
*ret = addr;
return 0;
}
struct ltelf;
int
arch_translate_address(struct ltelf *lte,
arch_addr_t addr, arch_addr_t *ret)
{
*ret = addr;
return 0;
}
#endif
void
breakpoint_on_hit(struct breakpoint *bp, struct process *proc)
{
assert(bp != NULL);
if (bp->cbs != NULL && bp->cbs->on_hit != NULL)
(bp->cbs->on_hit)(bp, proc);
}
void
breakpoint_on_continue(struct breakpoint *bp, struct process *proc)
{
assert(bp != NULL);
if (bp->cbs != NULL && bp->cbs->on_continue != NULL)
(bp->cbs->on_continue)(bp, proc);
else
continue_after_breakpoint(proc, bp);
}
void
breakpoint_on_retract(struct breakpoint *bp, struct process *proc)
{
assert(bp != NULL);
if (bp->cbs != NULL && bp->cbs->on_retract != NULL)
(bp->cbs->on_retract)(bp, proc);
}
void
breakpoint_on_install(struct breakpoint *bp, struct process *proc)
{
assert(bp != NULL);
if (bp->cbs != NULL && bp->cbs->on_install != NULL)
(bp->cbs->on_install)(bp, proc);
}
int
breakpoint_get_return_bp(struct breakpoint **ret,
struct breakpoint *bp, struct process *proc)
{
assert(bp != NULL);
if (bp->cbs != NULL && bp->cbs->get_return_bp != NULL)
return (bp->cbs->get_return_bp)(ret, bp, proc);
if ((*ret = create_default_return_bp(proc)) == NULL)
return -1;
return 0;
}
/*****************************************************************************/
struct breakpoint *
address2bpstruct(struct process *proc, arch_addr_t addr)
{
assert(proc != NULL);
assert(proc->breakpoints != NULL);
assert(proc->leader == proc);
debug(DEBUG_FUNCTION, "address2bpstruct(pid=%d, addr=%p)", proc->pid, addr);
struct breakpoint *found;
if (DICT_FIND_VAL(proc->breakpoints, &addr, &found) < 0)
return NULL;
return found;
}
#ifndef OS_HAVE_BREAKPOINT_DATA
int
os_breakpoint_init(struct process *proc, struct breakpoint *sbp)
{
return 0;
}
void
os_breakpoint_destroy(struct breakpoint *sbp)
{
}
int
os_breakpoint_clone(struct breakpoint *retp, struct breakpoint *sbp)
{
return 0;
}
#endif
#ifndef ARCH_HAVE_BREAKPOINT_DATA
int
arch_breakpoint_init(struct process *proc, struct breakpoint *sbp)
{
return 0;
}
void
arch_breakpoint_destroy(struct breakpoint *sbp)
{
}
int
arch_breakpoint_clone(struct breakpoint *retp, struct breakpoint *sbp)
{
return 0;
}
#endif
static void
breakpoint_init_base(struct breakpoint *bp,
arch_addr_t addr, struct library_symbol *libsym)
{
bp->cbs = NULL;
bp->addr = addr;
memset(bp->orig_value, 0, sizeof(bp->orig_value));
bp->enabled = 0;
bp->libsym = libsym;
}
/* On second thought, I don't think we need PROC. All the translation
* (arch_translate_address in particular) should be doable using
* static lookups of various sections in the ELF file. We shouldn't
* need process for anything. */
int
breakpoint_init(struct breakpoint *bp, struct process *proc,
arch_addr_t addr, struct library_symbol *libsym)
{
breakpoint_init_base(bp, addr, libsym);
if (os_breakpoint_init(proc, bp) < 0)
return -1;
if (arch_breakpoint_init(proc, bp) < 0) {
os_breakpoint_destroy(bp);
return -1;
}
return 0;
}
void
breakpoint_set_callbacks(struct breakpoint *bp, struct bp_callbacks *cbs)
{
if (bp->cbs != NULL)
assert(bp->cbs == NULL);
bp->cbs = cbs;
}
void
breakpoint_destroy(struct breakpoint *bp)
{
if (bp == NULL)
return;
arch_breakpoint_destroy(bp);
os_breakpoint_destroy(bp);
}
int
breakpoint_clone(struct breakpoint *retp, struct process *new_proc,
struct breakpoint *bp)
{
struct library_symbol *libsym = NULL;
if (bp->libsym != NULL) {
int rc = proc_find_symbol(new_proc, bp->libsym, NULL, &libsym);
assert(rc == 0);
}
breakpoint_init_base(retp, bp->addr, libsym);
memcpy(retp->orig_value, bp->orig_value, sizeof(bp->orig_value));
retp->enabled = bp->enabled;
if (os_breakpoint_clone(retp, bp) < 0)
return -1;
if (arch_breakpoint_clone(retp, bp) < 0) {
os_breakpoint_destroy(retp);
return -1;
}
breakpoint_set_callbacks(retp, bp->cbs);
return 0;
}
int
breakpoint_turn_on(struct breakpoint *bp, struct process *proc)
{
bp->enabled++;
if (bp->enabled == 1) {
assert(proc->pid != 0);
enable_breakpoint(proc, bp);
breakpoint_on_install(bp, proc);
}
return 0;
}
int
breakpoint_turn_off(struct breakpoint *bp, struct process *proc)
{
bp->enabled--;
if (bp->enabled == 0)
disable_breakpoint(proc, bp);
assert(bp->enabled >= 0);
return 0;
}
struct breakpoint *
create_default_return_bp(struct process *proc)
{
struct breakpoint *bp = malloc(sizeof *bp);
arch_addr_t return_addr = get_return_addr(proc, proc->stack_pointer);
if (return_addr == 0 || bp == NULL
|| breakpoint_init(bp, proc, return_addr, NULL) < 0) {
free(bp);
return NULL;
}
return bp;
}
struct breakpoint *
insert_breakpoint_at(struct process *proc, arch_addr_t addr,
struct library_symbol *libsym)
{
debug(DEBUG_FUNCTION,
"insert_breakpoint_at(pid=%d, addr=%p, symbol=%s)",
proc->pid, addr, libsym ? libsym->name : "NULL");
assert(addr != 0);
struct breakpoint *bp = malloc(sizeof *bp);
if (bp == NULL || breakpoint_init(bp, proc, addr, libsym) < 0) {
free(bp);
return NULL;
}
/* N.B. (and XXX): BP->addr might differ from ADDR. On ARM
* this is a real possibility. The problem here is that to
* create a return breakpoint ltrace calls get_return_addr and
* then insert_breakpoint_at. So get_return_addr needs to
* encode all the information necessary for breakpoint_init
* into the address itself, so ADDR is potentially
* mangled. */
struct breakpoint *tmp = insert_breakpoint(proc, bp);
if (tmp != bp) {
breakpoint_destroy(bp);
free(bp);
}
return tmp;
}
struct breakpoint *
insert_breakpoint(struct process *proc, struct breakpoint *bp)
{
/* Only the group leader should be getting the breakpoints and
* thus have ->breakpoint initialized. */
struct process *leader = proc->leader;
assert(leader != NULL);
assert(leader->breakpoints != NULL);
/* XXX what we need to do instead is have a list of
* breakpoints that are enabled at this address. The
* following works if every breakpoint is the same and there's
* no extra data, but that doesn't hold anymore. For now it
* will suffice, about the only realistic case where we need
* to have more than one breakpoint per address is return from
* a recursive library call. */
struct breakpoint *ext_bp = bp;
if (DICT_FIND_VAL(leader->breakpoints, &bp->addr, &ext_bp) != 0) {
if (proc_add_breakpoint(leader, bp) < 0)
return NULL;
ext_bp = bp;
}
if (breakpoint_turn_on(ext_bp, proc) < 0) {
if (ext_bp != bp)
proc_remove_breakpoint(leader, bp);
return NULL;
}
return ext_bp;
}
void
delete_breakpoint_at(struct process *proc, arch_addr_t addr)
{
debug(DEBUG_FUNCTION, "delete_breakpoint_at(pid=%d, addr=%p)",
proc->pid, addr);
struct process *leader = proc->leader;
assert(leader != NULL);
struct breakpoint *bp = NULL;
DICT_FIND_VAL(leader->breakpoints, &addr, &bp);
assert(bp != NULL);
if (delete_breakpoint(proc, bp) < 0) {
fprintf(stderr, "Couldn't turn off the breakpoint %s@%p\n",
breakpoint_name(bp), bp->addr);
}
}
int
delete_breakpoint(struct process *proc, struct breakpoint *bp)
{
struct process *leader = proc->leader;
assert(leader != NULL);
if (breakpoint_turn_off(bp, proc) < 0)
return -1;
if (bp->enabled == 0) {
proc_remove_breakpoint(leader, bp);
breakpoint_destroy(bp);
free(bp);
}
return 0;
}
const char *
breakpoint_name(const struct breakpoint *bp)
{
assert(bp != NULL);
return bp->libsym != NULL ? bp->libsym->name : NULL;
}
struct library *
breakpoint_library(const struct breakpoint *bp)
{
assert(bp != NULL);
return bp->libsym != NULL ? bp->libsym->lib : NULL;
}
static enum callback_status
disable_bp_cb(arch_addr_t *addr, struct breakpoint **bpp, void *data)
{
struct process *proc = data;
debug(DEBUG_FUNCTION, "disable_bp_cb(pid=%d)", proc->pid);
if ((*bpp)->enabled)
disable_breakpoint(proc, *bpp);
return CBS_CONT;
}
void
disable_all_breakpoints(struct process *proc)
{
debug(DEBUG_FUNCTION, "disable_all_breakpoints(pid=%d)", proc->pid);
assert(proc->leader == proc);
DICT_EACH(proc->breakpoints, arch_addr_t, struct breakpoint *,
NULL, disable_bp_cb, proc);
}
static void
entry_breakpoint_on_hit(struct breakpoint *bp, struct process *proc)
{
if (proc == NULL || proc->leader == NULL)
return;
delete_breakpoint_at(proc, bp->addr);
process_hit_start(proc);
}
int
entry_breakpoint_init(struct process *proc,
struct breakpoint *bp, arch_addr_t addr,
struct library *lib)
{
assert(addr != 0);
int err = breakpoint_init(bp, proc, addr, NULL);
if (err < 0)
return err;
static struct bp_callbacks entry_callbacks = {
.on_hit = entry_breakpoint_on_hit,
};
bp->cbs = &entry_callbacks;
return 0;
}
int
breakpoints_init(struct process *proc)
{
debug(DEBUG_FUNCTION, "breakpoints_init(pid=%d)", proc->pid);
/* XXX breakpoint dictionary should be initialized
* outside. Here we just put in breakpoints. */
assert(proc->breakpoints != NULL);
/* Only the thread group leader should hold the breakpoints. */
assert(proc->leader == proc);
/* N.B. the following used to be conditional on this, and
* maybe it still needs to be. */
assert(proc->filename != NULL);
struct library *lib = ltelf_read_main_binary(proc, proc->filename);
struct breakpoint *entry_bp = NULL;
int bp_state = 0;
int result = -1;
switch ((int)(lib != NULL)) {
fail:
switch (bp_state) {
case 2:
proc_remove_library(proc, lib);
proc_remove_breakpoint(proc, entry_bp);
case 1:
breakpoint_destroy(entry_bp);
}
library_destroy(lib);
free(entry_bp);
case 0:
return result;
}
entry_bp = malloc(sizeof(*entry_bp));
if (entry_bp == NULL
|| (entry_breakpoint_init(proc, entry_bp,
lib->entry, lib)) < 0) {
fprintf(stderr,
"Couldn't initialize entry breakpoint for PID %d.\n"
"Some tracing events may be missed.\n", proc->pid);
free(entry_bp);
} else {
++bp_state;
if ((result = proc_add_breakpoint(proc, entry_bp)) < 0)
goto fail;
++bp_state;
if ((result = breakpoint_turn_on(entry_bp, proc)) < 0)
goto fail;
}
proc_add_library(proc, lib);
proc->callstack_depth = 0;
return 0;
}