breakpoint.h revision cf98923cf77f12bef15b3f1af0c0bbd673a8e4f9 
1/*
2 * This file is part of ltrace.
3 * Copyright (C) 2012, 2013 Petr Machata, Red Hat Inc.
4 * Copyright (C) 2009 Juan Cespedes
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation; either version 2 of the
9 * License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
19 * 02110-1301 USA
20 */
21
22#ifndef BREAKPOINT_H
23#define BREAKPOINT_H
24
25/* XXX This is currently a very weak abstraction.  We would like to
26 * much expand this to allow things like breakpoints on SDT probes and
27 * such.
28 *
29 * In particular, we would like to add a tracepoint abstraction.
30 * Tracepoint is a traceable feature--e.g. an exact address, a DWARF
31 * symbol, an ELF symbol, a PLT entry, or an SDT probe.  Tracepoints
32 * are named and the user can configure which of them he wants to
33 * enable.  Realized tracepoints enable breakpoints, which are a
34 * low-level realization of high-level tracepoint.
35 *
36 * Service breakpoints like the handling of dlopen would be a
37 * low-level breakpoint, likely without tracepoint attached.
38 *
39 * So that's for sometimes.
40 */
41
42#include "sysdep.h"
43#include "library.h"
44#include "forward.h"
45
46struct bp_callbacks {
47	void (*on_hit)(struct breakpoint *bp, struct process *proc);
48	void (*on_continue)(struct breakpoint *bp, struct process *proc);
49	void (*on_retract)(struct breakpoint *bp, struct process *proc);
50
51	/* Create a new breakpoint that should handle return from the
52	 * function.  BP is the breakpoint that was just hit and for
53	 * which we wish to find the corresponding return breakpoint.
54	 * This returns 0 on success (in which case *RET will have
55	 * been initialized to desired breakpoint object, or NULL if
56	 * none is necessary) or a negative value on failure.  */
57	int (*get_return_bp)(struct breakpoint **ret,
58			     struct breakpoint *bp, struct process *proc);
59};
60
61struct breakpoint {
62	struct bp_callbacks *cbs;
63	struct library_symbol *libsym;
64	void *addr;
65	unsigned char orig_value[BREAKPOINT_LENGTH];
66	int enabled;
67	struct arch_breakpoint_data arch;
68	struct os_breakpoint_data os;
69};
70
71/* Call ON_HIT handler of BP, if any is set.  */
72void breakpoint_on_hit(struct breakpoint *bp, struct process *proc);
73
74/* Call ON_CONTINUE handler of BP.  If none is set, call
75 * continue_after_breakpoint.  */
76void breakpoint_on_continue(struct breakpoint *bp, struct process *proc);
77
78/* Call ON_RETRACT handler of BP, if any is set.  This should be
79 * called before the breakpoints are destroyed.  The reason for a
80 * separate interface is that breakpoint_destroy has to be callable
81 * without PROC.  ON_DISABLE might be useful as well, but that would
82 * be called every time we disable the breakpoint, which is too often
83 * (a breakpoint has to be disabled every time that we need to execute
84 * the instruction underneath it).  */
85void breakpoint_on_retract(struct breakpoint *bp, struct process *proc);
86
87/* Call GET_RETURN_BP handler of BP, if any is set.  If none is set,
88 * call CREATE_DEFAULT_RETURN_BP to obtain one.  */
89int breakpoint_get_return_bp(struct breakpoint **ret,
90			     struct breakpoint *bp, struct process *proc);
91
92/* Initialize a breakpoint structure.  That doesn't actually realize
93 * the breakpoint.  The breakpoint is initially assumed to be
94 * disabled.  orig_value has to be set separately.  CBS may be
95 * NULL.  */
96int breakpoint_init(struct breakpoint *bp, struct process *proc,
97		    arch_addr_t addr, struct library_symbol *libsym);
98
99/* Make a clone of breakpoint BP into the area of memory pointed to by
100 * RETP.  Symbols of cloned breakpoint are looked up in NEW_PROC.
101 * Returns 0 on success or a negative value on failure.  */
102int breakpoint_clone(struct breakpoint *retp, struct process *new_proc,
103		     struct breakpoint *bp);
104
105/* Set callbacks.  If CBS is non-NULL, then BP->cbs shall be NULL.  */
106void breakpoint_set_callbacks(struct breakpoint *bp, struct bp_callbacks *cbs);
107
108/* Destroy a breakpoint structure.   */
109void breakpoint_destroy(struct breakpoint *bp);
110
111/* Call enable_breakpoint the first time it's called.  Returns 0 on
112 * success and a negative value on failure.  */
113int breakpoint_turn_on(struct breakpoint *bp, struct process *proc);
114
115/* Call disable_breakpoint when turned off the same number of times
116 * that it was turned on.  Returns 0 on success and a negative value
117 * on failure.  */
118int breakpoint_turn_off(struct breakpoint *bp, struct process *proc);
119
120/* Allocate and initialize a default return breakpoint.  Returns NULL
121 * on failure.  */
122struct breakpoint *create_default_return_bp(struct process *proc);
123
124/* This allocates and initializes new breakpoint at ADDR, then calls
125 * INSERT_BREAKPOINT.  Returns the new breakpoint or NULL if there are
126 * errors.  */
127struct breakpoint *insert_breakpoint_at(struct process *proc, arch_addr_t addr,
128					struct library_symbol *libsym);
129
130/* Check if there is a breakpoint on this address already.  If yes,
131 * return that breakpoint instead (BP was not added).  If no, try to
132 * PROC_ADD_BREAKPOINT and BREAKPOINT_TURN_ON.  If it all works,
133 * return BP.  Otherwise return NULL.  */
134struct breakpoint *insert_breakpoint(struct process *proc,
135				     struct breakpoint *bp);
136
137/* Name of a symbol associated with BP.  May be NULL.  */
138const char *breakpoint_name(const struct breakpoint *bp);
139
140/* A library that this breakpoint comes from.  May be NULL.  */
141struct library *breakpoint_library(const struct breakpoint *bp);
142
143/* Again, this seems to be several interfaces rolled into one:
144 *  - breakpoint_disable
145 *  - proc_remove_breakpoint
146 *  - breakpoint_destroy
147 * XXX */
148void delete_breakpoint(struct process *proc, void *addr);
149
150/* XXX some of the following belongs to proc.h/proc.c.  */
151struct breakpoint *address2bpstruct(struct process *proc, void *addr);
152void enable_all_breakpoints(struct process *proc);
153void disable_all_breakpoints(struct process *proc);
154int breakpoints_init(struct process *proc);
155
156#endif /* BREAKPOINT_H */
157